SONOGENIC STIMULATION OF CELLS
The invention provides compositions featuring TRP-4 polypeptides and polynucleotides, methods for expressing such polypeptides and polynucleotides in a cell type of interest, and methods for inducing the activation of the TRP-4 polypeptide in neurons and other cell types using ultrasound.
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This application is a continuation of U.S. patent application Ser. No. 17/029,143, filed on Sep. 23, 2020, which is a continuation of U.S. patent application Ser. No. 14/843,108, filed on Sep. 2, 2015, now U.S. Pat. No. 10,806,951, which claims priority to and the benefit of U.S. Provisional Application No. 62/054,600, filed on Sep. 24, 2014, the entire contents of all of which are incorporated by reference herein.
STATEMENT OF RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCHThis work was supported by Grant No: NIH R01NM096881-03 from the National Institutes of Health. The government has certain rights in the invention.
SEQUENCE LISTINGThe present application contains a Sequence Listing which has been submitted electronically in XML format.
The content of the electronic XML Sequence Listing, (Date of creation: Aug. 30, 2023; Size: 17,389 bytes; Name: 167776-010203USCON2-Sequence_Listing.xml) is herein incorporated by reference in its entirety.
BACKGROUND OF THE INVENTIONUnderstanding how neural circuits generate specific behaviors requires an ability to identify the participating neurons, record and perturb their activity patterns. The best-understood motor circuit, the crab stomatogastric ganglion (STG) has benefited from electrophysiological access to well-defined cell types as well as an ability to manipulate them. A number of approaches have been developed for manipulating neuronal activity using light (optogenetics) or small molecules. While these methods have revealed insights into circuit computations in a number of model systems including mice, they suffer from one drawback: difficulty in delivering stimulus to the target neurons that are present in deeper brain regions. Methods for the non-invasive stimulation of target neurons and other cell types are required.
BRIEF SUMMARY OF THE INVENTIONThe invention provides compositions featuring TRP-4 polypeptides and polynucleotides, methods for expressing such polypeptides and polynucleotides in a cell type of interest, and methods for inducing the activation of the TRP-4 polypeptide in neurons and other cell types using ultrasound.
In one aspect, the invention provides a method of stimulating a cell, the method involving contacting a TRP-4 polypeptide expressing cell with ultrasound, thereby stimulating the cell. In one embodiment, the TRP-4 polypeptide comprises the amino acid sequence of SEQ ID NO: 1.
In another aspect, the invention provides a method of inducing cation influx in a cell, the method involving expressing a heterologous TRP-4 polypeptide in a cell, and applying ultrasound to the cell, thereby inducing cation influx in the cell. In one embodiment, the cell is a mammalian cell or bacterial cell (e.g, bacterial biofilm). In another embodiment, the TRP-4 polypeptide is encoded by a polynucleotide codon-optimized for expression in the cell. In another embodiment, the cell is muscle cell, cardiac muscle cell, neuron, motor neuron, sensory neuron, interneuron, or insulin secreting cell. In another embodiment, the ultrasound has a frequency of about 0.8 MHz to about 4 MHz. In another embodiment, the ultrasound has a focal zone of about 1 cubic millimeter to about 1 cubic centimeter. In another embodiment, the method further involves contacting the cell with a microbubble prior to applying ultrasound. In another embodiment, the cell is in vitro or in vivo.
In yet another aspect, the invention provides a method of treating a disease or disorder in a subject in need thereof, the method involving expressing in a cell (e.g., muscle cell, cardiac muscle cell, neuron, motor neuron, sensory neuron, interneuron, or insulin secreting cell) of a subject a heterologous nucleic acid molecule encoding a TRP-4 polypeptide; and applying ultrasound to the cell, thereby treating a disease or disorder in the subject. In one embodiment, the disease is a neurological disease selected from Parkinson Disease, depression, obsessive-compulsive disorder, chronic pain, epilepsy and cervical spinal cord injury. In another embodiment, the disorder is muscle weakness.
DefinitionsUnless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by a person of ordinary skill in the art. See, e.g., Singleton et al., DICTIONARY OF MICROBIOLOGY AND MOLECULAR BIOLOGY 2nd ed., J. Wiley & Sons (New York, NY 1994); Sambrook et al., MOLECULAR CLONING, A LABORATORY MANUAL, Cold Springs Harbor Press (Cold Springs Harbor, N Y 1989). Any methods, devices and materials similar or equivalent to those described herein can be used in the practice of this invention. The following definitions are provided to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure.
By TRP-4 polypeptide is meant a transient receptor potential cation channel capable of conferring ultrasound sensitivity on a neuron and having at least about 85% amino acid identity to SEQ ID NO: 1 or a human ortholog thereof.
For specific proteins described herein (e.g., TRP-4), the named protein includes any of the protein's naturally occurring forms, or variants or homologs that maintain the protein transcription factor activity (e.g., within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to the native protein). In some embodiments, variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring form. In other embodiments, the protein is the protein as identified by its NCBI sequence reference. In other embodiments, the protein is the protein as identified by its NCBI sequence reference or functional fragment or homolog thereof. In embodiments, the TRP-4 polypeptide is substantially identical to the protein identified by the NCBI reference number Gene ID: GI: 193247904 or a variant or homolog having substantial identity thereto. In embodiments, the TRP-4 polypeptide is the protein as identified by the NCBI sequence reference GI: 193247904. In embodiments, the TRP-4 polypeptide is the protein as identified by the NCBI sequence reference GI:193247904, homolog or functional fragment thereof. In embodiments, the TRP-4 polypeptide includes the amino acid sequence of SEQ ID NO: 1. In embodiments, the TRP-4 polypeptide is the amino acid sequence of SEQ ID NO: 1.
By “TRP-4 polynucleotide” is meant a nucleic acid molecule encoding a TRP-4 polypeptide. In particular embodiments, the codons of the TRP-4 polynucleotide are optimized for expression in an organism of interest (e.g., optimized for human expression, bacterial expression, murine expression). The sequence of an exemplary TRP-4 polynucleotide is provided herein below
For expression in a human cell, the following codon optimized sequence is used:
The term “amino acid” refers to naturally occurring and synthetic amino acids, as well as amino acid analogs and amino acid mimetics that function in a manner similar to the naturally occurring amino acids. Naturally occurring amino acids are those encoded by the genetic code, as well as those amino acids that are later modified, e.g., hydroxyproline, γ-carboxyglutamate, and O-phosphoserine. Amino acid analogs refers to compounds that have the same basic chemical structure as a naturally occurring amino acid, i.e., an a carbon that is bound to a hydrogen, a carboxyl group, an amino group, and an R group, e.g., homoserine, norleucine, methionine sulfoxide, methionine methyl sulfonium. Such analogs have modified R groups (e.g., norleucine) or modified peptide backbones, but retain the same basic chemical structure as a naturally occurring amino acid. Amino acid mimetics refers to chemical compounds that have a structure that is different from the general chemical structure of an amino acid, but that functions in a manner similar to a naturally occurring amino acid. The terms “non-naturally occurring amino acid” and “unnatural amino acid” refer to amino acid analogs, synthetic amino acids, and amino acid mimetics, which are not found in nature.
Amino acids may be referred to herein by either their commonly known three letter symbols or by the one-letter symbols recommended by the IUPAC-IUB Biochemical Nomenclature Commission. Nucleotides, likewise, may be referred to by their commonly accepted single-letter codes.
“Conservatively modified variants” applies to both amino acid and nucleic acid sequences. With respect to particular nucleic acid sequences, conservatively modified variants refers to those nucleic acids which encode identical or essentially identical amino acid sequences, or where the nucleic acid does not encode an amino acid sequence, to essentially identical sequences. Because of the degeneracy of the genetic code, a large number of functionally identical nucleic acids encode any given protein. For instance, the codons GCA, GCC, GCG and GCU all encode the amino acid alanine. Thus, at every position where an alanine is specified by a codon, the codon can be altered to any of the corresponding codons described without altering the encoded polypeptide. Such nucleic acid variations are “silent variations,” which are one species of conservatively modified variations. Every nucleic acid sequence herein, which encodes a polypeptide also describes every possible silent variation of the nucleic acid. One of skill will recognize that each codon in a nucleic acid (except AUG, which is ordinarily the only codon for methionine, and TGG, which is ordinarily the only codon for tryptophan) can be modified to yield a functionally identical molecule. Accordingly, each silent variation of a nucleic acid, which encodes a polypeptide is implicit in each described sequence with respect to the expression product, but not with respect to actual probe sequences.
By “altered” is meant an increase or decrease. An increase is any positive change, e.g., by at least about 5%, 10%, or 20%; preferably by about 25%, 50%, 75%, or even by 100%, 200%, 300% or more. A decrease is a negative change, e.g., a decrease by about 5%, 10%, or 20%; preferably by about 25%, 50%, 75%; or even an increase by 100%, 200%, 300% or more.
The terms “comprises”, “comprising”, and are intended to have the broad meaning ascribed to them in U.S. Patent Law and can mean “includes”, “including” and the like.
“Contacting” is used in accordance with its plain ordinary meaning and refers to the process of allowing at least two distinct species (e.g. chemical compounds including biomolecules, or cells) to become sufficiently proximal to react, interact, affect or physically touch. It should be appreciated, however, that the resulting reaction product can be produced directly from a reaction between the added reagents or from an intermediate from one or more of the added reagents, which can be produced in the reaction mixture. Contacting may include allowing two species to react, interact, or physically touch, wherein the two species may be a recombinant viral particle as described herein and a cell. In embodiments, the two species are an ultrasound contrast agent that is exposed to ultrasound and a cell.
The word “expression” or “expressed” as used herein in reference to a gene means the transcriptional and/or translational product of that gene. The level of expression of a DNA molecule in a cell may be determined on the basis of either the amount of corresponding mRNA that is present within the cell or the amount of protein encoded by that DNA produced by the cell. The level of expression of non-coding nucleic acid molecules (e.g., siRNA) may be detected by standard PCR or Northern blot methods well known in the art. See, Sambrook et al., 1989 Molecular Cloning: A Laboratory Manual, 18.1-18.88.
Expression of a transfected gene can occur transiently or stably in a cell. During “transient expression” the transfected gene is not transferred to the daughter cell during cell division. Since its expression is restricted to the transfected cell, expression of the gene is lost over time. In contrast, stable expression of a transfected gene can occur when the gene is co-transfected with another gene that confers a selection advantage to the transfected cell. Such a selection advantage may be a resistance towards a certain toxin that is presented to the cell. Expression of a transfected gene can further be accomplished by transposon-mediated insertion into to the host genome. During transposon-mediated insertion, the gene is positioned in a predictable manner between two transposon linker sequences that allow insertion into the host genome as well as subsequent excision. Stable expression of a transfected gene can further be accomplished by infecting a cell with a lentiviral vector, which after infection forms part of (integrates into) the cellular genome thereby resulting in stable expression of the gene.
The term “exogenous” refers to a molecule or substance (e.g., a compound, nucleic acid or protein) that originates from outside a given cell or organism. For example, an “exogenous promoter” as referred to herein is a promoter that does not originate from the plant it is expressed by. Conversely, the term “endogenous” or “endogenous promoter” refers to a molecule or substance that is native to, or originates within, a given cell or organism.
The term “gene” means the segment of DNA involved in producing a protein; it includes regions preceding and following the coding region (leader and trailer) as well as intervening sequences (introns) between individual coding segments (exons). The leader, the trailer as well as the introns include regulatory elements that are necessary during the transcription and the translation of a gene. Further, a “protein gene product” is a protein expressed from a particular gene.
The terms “identical” or percent “identity,” in the context of two or more nucleic acids or polypeptide sequences, refer to two or more sequences or subsequences that are the same or have a specified percentage of amino acid residues or nucleotides that are the same (i.e., about 60% identity, preferably 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or higher identity over a specified region, when compared and aligned for maximum correspondence over a comparison window or designated region) as measured using a BLAST or BLAST 2.0 sequence comparison algorithms with default parameters described below, or by manual alignment and visual inspection (see, e.g., NCBI web site http://www.ncbi.nlm.nih.gov/BLAST/or the like). Such sequences are then said to be “substantially identical.” This definition also refers to, or may be applied to, the compliment of a test sequence. The definition also includes sequences that have deletions and/or additions, as well as those that have substitutions. As described below, the preferred algorithms can account for gaps and the like. Preferably, identity exists over a region that is at least about 25 amino acids or nucleotides in length, or more preferably over a region that is 50-100 amino acids or nucleotides in length.
The term “isolated”, when applied to a nucleic acid or protein, denotes that the nucleic acid or protein is essentially free of other cellular components with which it is associated in the natural state. It can be, for example, in a homogeneous state and may be in either a dry or aqueous solution. Purity and homogeneity are typically determined using analytical chemistry techniques such as polyacrylamide gel electrophoresis or high performance liquid chromatography. A protein that is the predominant species present in a preparation is substantially purified.
By “mammal” is meant any warm-blooded animal including but not limited to a human, cow, horse, pig, sheep, goat, bird, mouse, rat, dog, cat, monkey, baboon, or the like. Preferably, the mammal is a human.
“Nucleic acid” refers to deoxyribonucleotides or ribonucleotides and polymers thereof in either single- or double-stranded form, or complements thereof. The term “polynucleotide” refers to a linear sequence of nucleotides. The term “nucleotide” typically refers to a single unit of a polynucleotide, i.e., a monomer. Nucleotides can be ribonucleotides, deoxyribonucleotides, or modified versions thereof. Examples of polynucleotides contemplated herein include single and double stranded DNA, single and double stranded RNA (including siRNA), and hybrid molecules having mixtures of single and double stranded DNA and RNA. The terms also encompass nucleic acids containing known nucleotide analogs or modified backbone residues or linkages, which are synthetic, naturally occurring, and non-naturally occurring, which have similar binding properties as the reference nucleic acid, and which are metabolized in a manner similar to the reference nucleotides. Examples of such analogs include, without limitation, phosphorothioates, phosphoramidates, methyl phosphonates, chiral-methyl phosphonates, and 2-O-methyl ribonucleotides.
Nucleic acid is “operably linked” when it is placed into a functional relationship with another nucleic acid sequence. For example, DNA for a presequence or secretory leader is operably linked to DNA for a polypeptide if it is expressed as a preprotein that participates in the secretion of the polypeptide; a promoter or enhancer is operably linked to a coding sequence if it affects the transcription of the sequence; or a ribosome binding site is operably linked to a coding sequence if it is positioned so as to facilitate translation. Generally, “operably linked” means that the DNA sequences being linked are near each other, and, in the case of a secretory leader, contiguous and in reading phase. However, enhancers do not have to be contiguous. Linking is accomplished by ligation at convenient restriction sites. If such sites do not exist, the synthetic oligonucleotide adaptors or linkers are used in accordance with conventional practice.
By “positioned for expression” is meant that a polynucleotide (e.g., a DNA molecule) is positioned adjacent to a DNA sequence, which directs transcription, and, for proteins, translation of the sequence (i.e., facilitates the production of, for example, a recombinant polypeptide of the invention, or an RNA molecule).
The term “plasmid” or “vector” refers to a nucleic acid molecule that encodes for genes and/or regulatory elements necessary for the expression of genes. Expression of a gene from a plasmid or vector can occur in cis or in trans. If a gene is expressed in cis, the gene and the regulatory elements are encoded by the same plasmid and vector. Expression in trans refers to the instance where the gene and the regulatory elements are encoded by separate plasmids or vectors.
As used herein, the terms “prevent,” “preventing,” “prevention,” “prophylactic treatment” and the like refer to reducing the probability of developing a disorder or condition in a subject, who does not have, but is at risk of or susceptible to developing a disorder or condition.
By “reference” or “control” is meant a standard condition. For example, an untreated cell, tissue, or organ that is used as a reference.
The terms “protein”, “peptide”, and “polypeptide” are used interchangeably to denote an amino acid polymer or a set of two or more interacting or bound amino acid polymers. The terms apply to amino acid polymers in which one or more amino acid residue is an artificial chemical mimetic of a corresponding naturally occurring amino acid, as well as to naturally occurring amino acid polymers and non-naturally occurring amino acid polymer.
The term “recombinant” when used with reference, e.g., to a cell, or nucleic acid, protein, or vector, indicates that the cell, nucleic acid, protein or vector, has been modified by the introduction of a heterologous nucleic acid or protein or the alteration of a native nucleic acid or protein, or that the cell is derived from a cell so modified. Thus, for example, recombinant cells express genes that are not found within the native (non-recombinant) form of the cell or express native genes that are otherwise abnormally expressed, under expressed or not expressed at all. Transgenic cells and plants are those that express a heterologous gene or coding sequence, typically as a result of recombinant methods.
The term “subject” as used herein refers to a vertebrate, preferably a mammal (e.g., dog, cat, rodent, horse, bovine, rabbit, goat, or human).
By “transformed cell” is meant a cell into which (or into an ancestor of which) has been introduced, by means of recombinant DNA techniques, a polynucleotide molecule encoding (as used herein) a polypeptide of the invention.
As used herein, the terms “treat,” treating,” “treatment,” and the like refer to reducing or ameliorating a disorder and/or symptoms associated therewith. It will be appreciated that, although not precluded, treating a disorder or condition does not require that the disorder, condition or symptoms associated therewith be completely eliminated.
By “transformed cell” is meant a cell into which (or into an ancestor of which) has been introduced, by means of recombinant DNA techniques, a polynucleotide molecule encoding (as used herein) a polypeptide of the invention.
The terms “transfection”, “transduction”, “transfecting” or “transducing” can be used interchangeably and are defined as a process of introducing a nucleic acid molecule or a protein to a cell. Nucleic acids are introduced to a cell using non-viral or viral-based methods. The nucleic acid molecules may be gene sequences encoding complete proteins or functional portions thereof. Non-viral methods of transfection include any appropriate transfection method that does not use viral DNA or viral particles as a delivery system to introduce the nucleic acid molecule into the cell. Exemplary non-viral transfection methods include calcium phosphate transfection, liposomal transfection, nucleofection, sonoporation, transfection through heat shock, magnetofection and electroporation. In some embodiments, the nucleic acid molecules are introduced into a cell using electroporation following standard procedures well known in the art. For viral-based methods of transfection any useful viral vector may be used in the methods described herein. Examples for viral vectors include, but are not limited to retroviral, adenoviral, lentiviral and adeno-associated viral vectors. In some embodiments, the nucleic acid molecules are introduced into a cell using a retroviral vector following standard procedures well known in the art. The terms “transfection” or “transduction” also refer to introducing proteins into a cell from the external environment. Typically, transduction or transfection of a protein relies on attachment of a peptide or protein capable of crossing the cell membrane to the protein of interest. See, e.g., Ford et al. (2001) Gene Therapy 8:1-4 and Prochiantz (2007) Nat. Methods 4:119-20.
As used herein, the terms “treat,” treating,” “treatment,” and the like refer to reducing or ameliorating a disorder and/or symptoms associated therewith. It will be appreciated that, although not precluded, treating a disorder or condition does not require that the disorder, condition or symptoms associated therewith be completely eliminated.
An “effective amount” is an amount sufficient to accomplish a stated purpose (e.g. achieve the effect for which it is administered, treat a disease, reduce enzyme activity, reduce one or more symptoms of a disease or condition, reduce viral replication in a cell). An example of an “effective amount” is an amount sufficient to contribute to the treatment, prevention, or reduction of a symptom or symptoms of a disease, which could also be referred to as a “therapeutically effective amount.” A “reduction” of a symptom or symptoms (and grammatical equivalents of this phrase) means decreasing of the severity or frequency of the symptom(s), or elimination of the symptom(s). A “prophylactically effective amount” of a drug is an amount of a drug that, when administered to a subject, will have the intended prophylactic effect, e.g., preventing or delaying the onset (or reoccurrence) of an injury, disease, pathology or condition, or reducing the likelihood of the onset (or reoccurrence) of an injury, disease, pathology, or condition, or their symptoms. The full prophylactic effect does not necessarily occur by administration of one dose, and may occur only after administration of a series of doses. Thus, a prophylactically effective amount may be administered in one or more administrations. An “activity decreasing amount,” as used herein, refers to an amount of antagonist required to decrease the activity of an enzyme or protein (e.g. Tat, Rev) relative to the absence of the antagonist. A “function disrupting amount,” as used herein, refers to the amount of antagonist required to disrupt the function of an enzyme or protein relative to the absence of the antagonist. The exact amounts will depend on the purpose of the treatment, and will be ascertainable by one skilled in the art using known techniques (see, e.g., Lieberman, Pharmaceutical Dosage Forms (vols. 1-3, 1992); Lloyd, The Art, Science and Technology of Pharmaceutical Compounding (1999); Pickar, Dosage Calculations (1999); and Remington: The Science and Practice of Pharmacy, 20th Edition, 2003, Gennaro, Ed., Lippincott, Williams & Wilkins).
“Patient” or “subject in need thereof” refers to a living organism suffering from or prone to a disease or condition that can be treated by using the methods provided herein. The term does not necessarily indicate that the subject has been diagnosed with a particular disease, but typically refers to an individual under medical supervision. Non-limiting examples include humans, other mammals, bovines, rats, mice, dogs, monkeys, goat, sheep, cows, deer, and other non-mammalian animals. In embodiments, a patient is human.
The invention provides compositions featuring TRP-4 polypeptides and polynucleotides, methods for expressing such polypeptides and polynucleotides in a cell type of interest, and methods for inducing the activation of the TRP-4 polypeptide in neurons and other cell types using ultrasound.
The invention is based, at least in part, on the discovery that misexpression of TRP-4, a pore-forming subunit of a mechanotransduction channel, sensitizes cells to an ultrasound stimulus resulting in calcium influx and motor outputs. Accordingly, this approach can be used to alter cellular functions in vivo.
Accordingly, the invention provides polynucleotides encoding a TRP4 polypeptide, expression vectors comprising such polynucleotides, cells expressing a recombinant TRP4 polypeptide, and methods for stimulating such cells with ultrasound.
UltrasoundUltrasound is well suited for stimulating neuron populations as it focuses easily through intact thin bone and deep tissue (K. Hynynen and F. A. Jolesz, Ultrasound Med Biol 24 (2), 275 (1998)) to volumes of just a few cubic millimeters (G. T. Clement and K. Hynynen, Phys Med Biol 47 (8), 1219 (2002)). The non-invasive nature of ultrasound stimulation is particularly significant for manipulating vertebrate neurons including those in humans, as it eliminates the need for surgery to insert light fibers (required for some current optogenetic methods). Also, the small focal volume of the ultrasound wave compares well with light that is scattered by multiple layers of brain tissue (S. I. Al-Juboori, A. Dondzillo, E. A. Stubblefield et al., PLoS ONE 8 (7), e67626 (2013)). Moreover, ultrasound has been previously used to manipulate deep nerve structures in human hands and reduce chronic pain (W. D. O'Brien, Jr., Prog Biophys Mol Biol 93 (1-3), 212 (2007); L. R. Gavrilov, G. V. Gersuni, O. B. Ilyinsky et al., Prog Brain Res 43, 279 (1976)). The invention provides for novel non-invasive compositions for the expression of TRP4 in cells, and methods to stimulate cells expressing TRP4 using low-intensity ultrasound stimulation.
Cellular Compositions Comprising Recombinant TRP-4The invention provides cells comprising a recombinant nucleic acid molecule encoding a TRP-4 polypeptide. In one embodiment, the invention provides a cardiac muscle cell comprising a TRP-4 polynucleotide under the control of a promoter suitable for expression in a cardiac cell (e.g., NCX1 promoter). In another embodiment, the invention provides a muscle cell comprising a TRP-4 polynucleotide under the control of a promoter suitable for expression in a muscle cell (e.g., myoD promoter). In another embodiment, the invention provides an insulin secreting cell (e.g., beta islet cell) comprising a TRP-4 polynucleotide under the control of a promoter suitable for expression in an insulin-secreting cell (e.g., Pdx1 promoter). In another embodiment, the invention provides an adipocyte comprising a TRP-4 polynucleotide under the control of a promoter suitable for expression in an adipocyte (e.g., iaP2). In another embodiment, the invention provides a neuron comprising a TRP-4 polynucleotide under the control of a promoter suitable for expression in a neuron (e.g., nestin, Tuj1 promoter), in a motor neuron (e.g., H2b promoter), in an interneuron (e.g., Islet 1 promoter), in a sensory neuron (e.g., OMP promoter, T1R, T2R promoter, rhodopsin promoter, Trp channel promoter). Such cells may be cells in vitro or in vivo. In particular embodiments, the cells express a mechanotransduction polypeptide that is a transient receptor potential channel-N (TRPN) polypeptide that is sensitive to ultrasound. In particular embodiments, the mechanotransduction polypeptide is TRP-4 or a functional portion or homolog thereof. In embodiments, the mechanotransduction polypeptide comprises or consists of the amino acid sequence of SEQ ID NO: 1.
Expression of Recombinant TRP-4In one approach, a cell of interest (e.g., neuron, such as a motor neuron, sensory neuron, neuron of the central nervous system, or neuronal cell lines) is engineered to express a TRP-4 polynucleotide whose expression renders the cell responsive to ultrasound stimulation. Ultrasound stimulation of such cells induces cation influx.
TRP-4 may be constitutively expressed or its expression may be regulated by an inducible promoter or other control mechanism where conditions necessitate highly controlled regulation or timing of the expression of a TRP-4 protein. For example, heterologous DNA encoding a TRP4 gene to be expressed is inserted in one or more pre-selected DNA sequences. This can be accomplished by homologous recombination or by viral integration into the host cell genome. The desired gene sequence can also be incorporated into a cell, particularly into its nucleus, using a plasmid expression vector and a nuclear localization sequence. Methods for directing polynucleotides to the nucleus have been described in the art. The genetic material can be introduced using promoters that will allow for the gene of interest to be positively or negatively induced using certain chemicals/drugs, to be eliminated following administration of a given drug/chemical, or can be tagged to allow induction by chemicals, or expression in specific cell compartments.
Calcium phosphate transfection can be used to introduce plasmid DNA containing a target gene or polynucleotide into cells and is a standard method of DNA transfer to those of skill in the art. DEAE-dextran transfection, which is also known to those of skill in the art, may be preferred over calcium phosphate transfection where transient transfection is desired, as it is often more efficient. Since the cells of the present invention are isolated cells, microinjection can be particularly effective for transferring genetic material into the cells. This method is advantageous because it provides delivery of the desired genetic material directly to the nucleus, avoiding both cytoplasmic and lysosomal degradation of the injected polynucleotide. Cells can also be genetically modified using electroporation.
Liposomal delivery of DNA or RNA to genetically modify the cells can be performed using cationic liposomes, which form a stable complex with the polynucleotide. For stabilization of the liposome complex, dioleoyl phosphatidylethanolamine (DOPE) or dioleoyl phosphatidylcholine (DOPQ) can be added. Commercially available reagents for liposomal transfer include Lipofectin (Life Technologies). Lipofectin, for example, is a mixture of the cationic lipid N-[1-(2, 3-dioleyloxy)propyl]-N—N—N-trimethyl ammonia chloride and DOPE. Liposomes can carry larger pieces of DNA, can generally protect the polynucleotide from degradation, and can be targeted to specific cells or tissues. Cationic lipid-mediated gene transfer efficiency can be enhanced by incorporating purified viral or cellular envelope components, such as the purified G glycoprotein of the vesicular stomatitis virus envelope (VSV-G). Gene transfer techniques which have been shown effective for delivery of DNA into primary and established mammalian cell lines using lipopolyamine-coated DNA can be used to introduce target DNA into the de-differentiated cells or reprogrammed cells described herein.
Naked plasmid DNA can be injected directly into a tissue comprising cells of interest. Microprojectile gene transfer can also be used to transfer genes into cells either in vitro or in vivo. The basic procedure for microprojectile gene transfer was described by J. Wolff in Gene Therapeutics (1994), page 195. Similarly, microparticle injection techniques have been described previously, and methods are known to those of skill in the art. Signal peptides can be also attached to plasmid DNA to direct the DNA to the nucleus for more efficient expression.
Viral vectors are used to genetically alter cells of the present invention and their progeny. Viral vectors are used, as are the physical methods previously described, to deliver one or more polynucleotide sequences encoding TRP4, for example, into the cells. Viral vectors and methods for using them to deliver DNA to cells are well known to those of skill in the art. Examples of viral vectors that can be used to genetically alter the cells of the present invention include, but are not limited to, adenoviral vectors, adeno-associated viral vectors, retroviral vectors (including lentiviral vectors), alphaviral vectors (e. g., Sindbis vectors), and herpes virus vectors.
Targeted Cell TypesTRP-4 can be expressed in virtually any eukaryotic or prokaryotic cell of interest. In one embodiment, the cell is a bacterial cell or other pathogenic cell type. In another embodiment, the cell is a mammalian cell, such as an adipocyte, muscle cell, cardiac muscle cell, insulin secreting cell (e.g., beta islet cell), and neuron (e.g., motor neuron, sensory neuron, neuron of the central nervous system, and neuronal cell line).
Methods of Stimulating a Neural CellThe methods provided herein are, inter alia, useful for the stimulation (activation) of cells. In particular, ultrasound stimulation induces cation influx, thereby altering cell activity. Expression of TRP-4 in a pathogen cell (bacteria) and subsequent ultrasound stimulation induces cation influx and bacterial cell killing. Ultrasound stimulation of a muscle cell expressing TRP-4 results in muscle contraction. This can be used to enhance muscle contraction or functionality in subjects in need thereof, including subjects suffering from muscle weakness, paralysis, or muscle wasting. Altering the intensity of the ultrasound modulates the extent of muscle activity.
The term “neural cell” as provided herein refers to a cell of the brain or nervous system. Non-limiting examples of neural cells include neurons, glia cells, astrocytes, oligodendrocytes and microglia cells. Where a neural cell is stimulated, a function or activity (e.g., excitability) of the neural cell is modulated by modulating, for example, the expression or activity of a given gene or protein (e.g., TRP-4) within said neural cell. The change in expression or activity may be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or more in comparison to a control (e.g., unstimulated cell). In certain instances, expression or activity is 1.5-fold, 2-fold, 3-fold, 4-fold, 5-fold, 10-fold or higher than the expression or activity in the absence of stimulation. In certain instances, expression or activity is 1.5-fold, 2-fold, 3-fold, 4-fold, 5-fold, 10-fold or lower than the expression or activity in the absence of stimulation. The neural cell may be stimulated by applying an ultrasonic wave to the neural cell.
The term “applying” as provided herein is used in accordance with its plain ordinary meaning and includes the meaning of the terms contacting, introducing and exposing. An “ultrasonic wave” as provided herein is an oscillating sound pressure wave having a frequency greater than the upper limit of the human hearing range. Ultrasound (ultrasonic wave) is thus not separated from ‘normal’ (audible) sound by differences in physical properties, only by the fact that humans cannot hear it. Although this limit varies from person to person, it is approximately 20 kilohertz (20,000 hertz) in healthy, young adults. Ultrasound (ultrasonic wave) devices operate with frequencies from 20 kHz up to several gigahertz. The methods provided herein use the energy of an ultrasonic wave to stimulate a neural cell expressing an exogenous mechanotransduction protein. A mechanotransduction protein as provided herein refers to a cellular protein capable of converting a mechanical stimulus (e.g., sound, pressure, movement) into chemical activity. Cellular responses to mechanotransduction are variable and give rise to a variety of changes and sensations. In embodiments, the mechanotransduction protein is a mechanically gated ion channel, which makes it possible for sound, pressure, or movement to cause a change in the excitability of a cell (e.g., a sensory neuron). The stimulation of a mechanotransduction protein may cause mechanically sensitive ion channels to open and produce a transduction current that changes the membrane potential of a cell.
In one aspect, a method of stimulating a cell is provided. The method includes (i) transfecting a cell with a recombinant vector including a nucleic acid sequence encoding an exogenous mechanotransduction polypeptide, thereby forming a transfected cell. (ii) To the transfected cell an ultrasonic wave is applied, thereby stimulating a cell. In embodiments, the mechanotransduction polypeptide is a transient receptor potential channel-N (TRPN) polypeptide or homolog thereof. In embodiments, the mechanotransduction polypeptide is TRP-4 or a functional portion or homolog thereof. In embodiments, the mechanotransduction polypeptide includes the amino acid sequence of TRP4 SEQ ID NO: 1. In embodiments, the mechanotransduction polypeptide is the sequence of SEQ ID NO: 1. In embodiments, the ultrasonic wave has a frequency of about 0.8 MHz to about 4 MHz. In embodiments, the ultrasonic wave has a frequency of about 1 MHz to about 3 MHz. In embodiments, the ultrasonic wave has a focal zone of about 1 cubic millimeter to about 1 cubic centimeter.
In embodiments, the method further includes before the applying of step (ii) contacting the transfected neural cell with an ultrasound contrast agent. In embodiments, the ultrasound contrast agent is a microbubble. In embodiments, the microbubble has a diameter of about 1 μm to about 6 μm. In embodiments, the neural cell forms part of an organism. In embodiments, the organism is a bacterial cell or mammalian cell (e.g., human, murine, bovine, feline, canine).
Methods of TreatmentIn another aspect, a method of treating a neurological disease in a subject in need thereof is provided. The method includes (i) administering to a subject a therapeutically effective amount of a recombinant nucleic acid encoding an exogenous mechanotransduction polypeptide (e.g., TRP-4). In step (ii) an ultrasonic wave is applied to the subject, resulting in a change in TRP-4 conductance, i.e., cation influx. In one embodiment, the methods treat a cardiac disease by enhancing cardiac muscle activity or neurological disease by altering neural activity in the subject. In embodiments, the neurological disease is Parkinson Disease, depression, obsessive-compulsive disorder, chronic pain, epilepsy or cervical spinal cord injury. In embodiments, the neurological disease is retinal degeneration or atrial fibrillation. In embodiments, the mechanotransduction polypeptide is a transient receptor potential channel-N (TRPN) polypeptide or homolog thereof. In embodiments, the mechanotransduction polypeptide is TRP-4 or a functional portion or homolog thereof. In embodiments, the method further includes before the applying of step (ii) administering to the subject an ultrasound contrast agent. In embodiments, the ultrasound contrast agent is a microbubble. In embodiments, the microbubble has a diameter of about 1 μm to about 6 μm, and is injected into the body (e.g., the brain) where it enhances ultrasound stimulation.
EXAMPLESReliable activation of identified neurons, particularly those in deeper brain regions remains a major challenge in neuroscience. Here, Applicants demonstrate low intensity ultrasound as a non-invasive trigger to activate neurons in the nematode, Caenorhabditis elegans. Applicants show that neuron-specific misexpression of TRP-4, the pore-forming subunit of a mechanotransduction channel, activates those cells in response to ultrasound stimuli and initiates behavior. Applicants suggest that this method can be broadly used to manipulate cellular functions in vivo.
To probe the effects of ultrasound on neuronal function, Applicants chose the nematode C. elegans, with its small nervous system consisting of just 302 neurons (J. G. White, E. Southgate, J. N. Thomson et al., Phil. Transact. R. Soc. Lond. B 314, 1 (1986)), and strong correlations between individual neurons and robust behaviors (M. de Bono and A. V. Maricq, Annu Rev Neurosci 28, 451 (2005); C. I. Bargmann, WormBook, 1 (2006); R. O'Hagan and M. Chalfie, Int Rev Neurobiol 69, 169 (2006)).
Example 1: Imaging Setup Delivers Ultrasound Waves to AnimalsTo investigate the role of ultrasound on C. elegans behavior, Applicants developed a novel imaging setup (
Applicants used data from a previous study to estimate the mechanical deformation of the low intensity ultrasound wave (A. P. Brysev, A. F. Bunkin, R. V. Klopotov et al., Opt. Spectrosc. 93 (2), 282 (2002)). Applicants estimate that at this intensity, the ultrasound wave is likely to pass through C. elegans causing a mechanical deformation of 0.005 nm, and hypothesized that this small change is unlikely to influence cellular functions in vivo. This hypothesis is consistent with previous studies, which have shown that mechanical changes of this magnitude do not modify either neurons or non-neurons (S. Ito, H. Kume, K. Naruse et al., Am J Respir Cell Mol Biol 38 (4), 407 (2008); K. Shibasaki, N. Murayama, K. Ono et al., J Neurosci 30 (13), 4601 (2010)).
Moreover, Applicants found that a single 10 ms duration ultrasound pulse of 2.25 MHz and peak negative pressures below 0.9 MPa had no effect on animal behavior. The mechanical disturbances of the fluid and tissue in the ultrasound focal zone take the form of compression and expansion deformations as well as bulk tissue distortions caused by acoustic radiation forces, but at low-pressures they were not large enough to influence C. elegans locomotion. Previous studies have shown that ultrasound waves can cause temperature changes in the focal zone. Applicants first estimated the temperature increase as a result of ultrasound exposure. In a previous study, a continuous 1.1 MHz ultrasound pulse with a peak negative pressure of 2.6 MPa increased the temperature of the surrounding media at the rate of 35° C./sec. Using these data, Applicants estimated that the temperature increase around the worms on the agar surface to be 0.04° C. for single ultrasound pulse at 0.9 MPa. Moreover, Applicants directly measured the magnitude of temperature change on the agar surface using a miniature thermocouple and found that an ultrasound peak negative pressure of 0.7 MPa caused a temperature increase of less than 0.1° C. This is a temperature stimulus that animals including C. elegans are unlikely to detect. Together, these results show that C. elegans is unlikely to respond to the temperature and mechanical changes induced by the low-pressure ultrasound wave.
Example 2: Microbubbles Amplify the Mechanical Deformation of the Ultrasound WaveTo amplify the ultrasound wave, Applicants included gas-filled microbubbles in Applicants' assay (
Applicants hypothesized that ultrasound is a mechanical stimulus that require specific mechanotransduction channels to transduce the signals in individual neurons. Applicants tested the ability of TRP-4, a pore forming cation-selective mechanotransduction channel (L. Kang, J. Gao, W. R. Schafer et al., Neuron 67 (3), 381 (2010); W. Li, Z. Feng, P. W. Sternberg et al., Nature 440 (7084), 684 (2006)), to transduce this ultrasound induced mechanical stimulus. This channel is specifically expressed in a few C. elegans neurons, the four CEPs (CEPDL, CEPDR, CEPVL and CEPVR) and the two ADE (ADEL and ADER) dopaminergic neurons and the DVA and DVC interneurons (L. Kang, J. Gao, W. R. Schafer et al., Neuron 67 (3), 381 (2010); W. Li, Z. Feng, P. W. Sternberg et al., Nature 440 (7084), 684 (2006)). TRP-4 is both necessary and sufficient to generate mechanoreceptor currents in CEP neurons. Applicants found that animals missing TRP-4 have reduced responses to specific intensities (0.41 and 0.47 MPa peak negative pressure) of ultrasound stimulation, which suggests that this channel is required to generate reversals (
To test whether ultrasound sensitivity could be conferred to additional neurons, Applicants analyzed the behavior of transgenic animals misexpressing TRP-4 in specific chemosensory neurons. Applicants initially misexpressed this channel in ASH, a well-studied polymodal nociceptive neuron (M. A. Hilliard, C. Bergamasco, S. Arbucci et al., Embo J 23 (5), 1101 (2004)), whose activation leads to reversals and omega bends (Z. V. Guo, A. C. Hart, and S. Ramanathan, Nat Methods 6 (12), 891 (2009)). Consistently, Applicants found that ASH expression of TRP-4 generated a significant increase in reversals at ultrasound intensity with a peak negative pressure of 0.47 MPa (
Interestingly, FLP neurons do not respond to ultrasound (
To test Applicants' approach of analyzing neuronal function by misexpressing TRP-4, Applicants probed the functions of poorly understood PVD neurons (
Applicants' studies show that C. elegans neural circuits can be probed by combining ultrasound stimulation with microbubbles that amplify the mechanical deformations. Specifically, Applicants find that upon activation ASH and AWC sensory neurons increase in reversals, while activating PVD neurons suppresses reversals (
Applicants then tested whether this approach can manipulate the function of an interneuron, whose processes do not contact the external cuticle of the animal. Applicants misexpressed TRP-4 in AIY interneurons, which are at least 25 μm from the cuticle, and analyzed the behavior of these animals upon ultrasound stimulation. Optogenetic studies have previously shown that activating AIY interneurons reduces turns. In contrast, Applicants find that AIY::trp-4 transgenics are significantly more likely to initiate high-angled omega bends upon ultrasound stimulation (two independent transgenics). It is possible that expressing TRP-4 in AIY neurons has altered that neuron's function, leading to increased turns. However, animals with genetically altered AIY function have been shown to have increased turns in a local search assay. Applicants found that these AIY::trp-4 transgenics did not show any defects in local search (
To confirm whether ultrasound stimulus is activating AIY interneurons, we used calcium imaging. AIY neural activity is typically measured from a bulb in the AIY neurite. Consistent with previous observation, Applicants found that AIY is a noisy neuron with a number of transients during recordings (
These studies show that C. elegans neural circuits can be probed by combining low-pressure ultrasound stimulation with microbubbles that amplify the mechanical deformations. Specifically, Applicants found that C. elegans are insensitive to low-pressure ultrasound but respond when surrounded by microbubbles. Applicants found that animals missing the TRP-4 mechanosensitive ion channel have significantly reduced sensitivity to the ultrasound-microbubble stimulation, indicating that mechanosensitive ion channels play an important role in the mechanism of ultrasound stimulation. Applicants also found that misexpressing the TRP-4 mechanosensitive ion channel in specific neurons modifies their neural activity upon ultrasound stimulation, resulting in altered animal behaviors. Specifically, misexpressing TRP-4 in ASH and AWC sensory neurons results in an increase in large reversals, while activating PVD neurons suppresses this behavior. Applicants also defined novel roles for PVD neurons in suppressing reversal behavior and AIY neurons in stimulating omega bend behavior.
These novel methods provide new insights into the neural activity patterns that drive whole-animal behavior. Persistent AWC neural activity might drive reversal behavior, providing a correlation between a distinct AWC neuronal activity pattern and whole-animal behavior. Ultrasound stimulation may activate neurons with different kinetics than what has been seen using optogenetics. For example, activating AIY interneurons using light leads to an increase in forward turns, while using low-pressure ultrasound increases omega bend frequency. These studies indicate an alternative role for AIY in promoting omega bends. The stimulation of AIY interneurons demonstrates that this ultrasound technique can also be applied to deep internal neurons that do not contact the skin of the worm. Taken together, these results and other studies show that TRP channels can be used to manipulate neuronal functions and thus provide insight into how neural circuits transform environmental changes into precise behaviors.
In order to target smaller groups of neurons, the resolution of the ultrasound focal zone can be made smaller than the 1 mm diameter. Frequencies above 2.25 MHz can produce sub-millimeter focal zone spot sizes. Higher frequency ultrasound waves with their smaller focal zones are better suited to targets that are closer to the body surface as these waves do not penetrate tissues as well. One of the advantages of ultrasound is that small focal zones can be maintained noninvasively even in deep brain tissue. Outside the focal zone the peak negative pressures are significantly lower and are unlikely to result in neuron activation. This was seen on the agar plates where only worms that were in the focal zone responded to the ultrasound and nearby worms that were outside the focal zone did not. Another advantage of ultrasound is that this focal zone can be moved arbitrarily within the tissue to simulate different regions without any invasive procedures. With an electronically steerable ultrasound beam, multiple different targets can be noninvasively manipulated either simultaneously or in rapid succession. Moreover, the genetic targeting of the stretch sensitive ion channels to individual neurons allows for targeting well below the resolution of the ultrasound focal zone.
The use of ultrasound as a non-invasive neuronal activator can be broadly applied to decode neural circuits in larger vertebrate brains with opaque skin and intact skulls. Ultrasound waves with peak negative pressures of <1 MPa have been shown to penetrate through skull and brain tissue with very little impedance or tissue damage. These results show that low-pressure ultrasound (with peak negative pressures 0.4-0.6 MPa) specifically activates neurons expressing the TRP-4 channel. Moreover, TRP-4 channels do not have mammalian homologs, therefore, it is unlikely that expressing these channels in the mammalian brain would produce deleterious effects. This suggests that neurons in diverse model organisms misexpressing this channel can be activated by ultrasound stimulation, allowing scientists to probe their functions in influencing animal behavior. Additionally, other mechanosensitive channels can be explored that may be more sensitive to mechanic deformations than TRP-4. Of particular interest are the bacterial MscL and MscS channels that have different sensitivities to membrane stretch and are selective for different ions. Moreover, TRP-4 and other channels may be mutated in and around the pore region in order to change their ion selectivity as well as their sensitivity to mechanical stretch to broaden the utility of this method.
Furthermore, if low-pressure ultrasound stimulation by itself does not activate TRP-4 expressing neurons, the mechanical signals can be amplified by gas-filled microbubbles. Perfluorohexane microbubbles are well-established for use as ultrasound contrast agents in vivo and can be administered intravenously to circulate throughout the vertebrate body including the brain. They can remain active for up to 60 minutes providing a time window where they could be used safely to amplify the ultrasound stimulus and manipulate neural activity. Microbubbles have been shown to undergo inertial cavitation when exposed to ultrasound with peak negative pressure of 0.58 MPa and higher. Using ultrasound pressure levels lower than this will prevent damage to the brain from the microbubble-ultrasound interaction. Moreover, Applicants used a third of the number of microbubbles that has been previously used to successfully image the mouse brain showing that the required microbubble dose would not be prohibitive for in vivo administration. These experiments show that in the presence of microbubbles the low pressure ultrasound stimulated the deep AIY interneurons expressing TRP-4. This result enables Applicants to estimate the distances at which the mechanical deformations from the ultrasound-microbubble interaction can effectively penetrate into brain tissue from the vasculature. The C. elegans cuticle is 0.5 μm thick and the AIY interneurons are 25 μm from the cuticle, indicating that the mechanical deformations traveled at least 25.5 μm into the worm. In contrast, the mammalian blood-brain barrier is 0.2 μm thick and the average distance of a neuron from a capillary is less than 20 μm. These distances are well within the range of the sonogenetic approach. With the data presented in this paper, the invention provides a novel, non-invasive approach to activate genetically targeted neurons using low-pressure ultrasound stimulation
The results described herein above were carried out using the following materials and methods.
Behavioral Assay
Well-fed young adults were placed on an empty NGM agar plate and corralled into a small area using a filter paper soaked in copper solution (200 mM). A solution (15 μl) of microbubbles at a density of 3.8×107/ml was added to the plate with worms. The worms were allowed to crawl around for 10 minutes before being stimulated by ultrasound. An animal was moved into the fixed ultrasound focal zone and stimulated with one pulse and the resulting reversal and omega bend response is recorded. Reversals with fewer than two head bends were identified as small, while those with more than two were counted as large. High-angled turns that lead to a significant change in the direction of an animal's movement were identified as omega bends (
Imaging
Transgenic animals expressing GCaMP in specific neurons were corralled into a small area by filter paper soaked in copper solution (as described above). The acetylcholine agonist and paralytic, tetramisole (J. A. Lewis, C. H. Wu, J. H. Levine et al., Neuroscience 5 (6), 967 (1980)), was used at 1.3 mM to paralyze the animals to facilitate recording neural activity. These animals were surrounded by a solution of microbubbles and stimulated using ultrasound intensities as described. Fluorescence was recorded at 10 frames/second using an EMCCD camera (Photometrics, Quant-EM) and resulting movies were analyzed using Metamorph software (Molecular Devices) as described (S. H. Chalasani, N. Chronis, M. Tsunozaki et al., Nature 450 (7166), 63 (2007)). Briefly, a fluorescence baseline was calculated using a 3-second window from t=1 to t=4 seconds. The ratio of change in fluorescence to baseline fluorescence was plotted in all graphs using custom MATLAB scripts (S. H. Chalasani, N. Chronis, M. Tsunozaki et al., Nature 450 (7166), 63 (2007)). For imaging PVD neurons, the concentration of the paralytic was reduced to 1 mM, which allowed these animals greater movement. Their motion along with the corresponding fluorescent intensity changes was captured and analyzed using Metamorph software.
Microbubble Synthesis
Microbubbles were made using a probe sonication technique as described (C. E. Schutt, S. D. Ibsen, M. J. Benchimol et al., Small (2014)). The stabilizing lipid monolayer consisted of distearoyl phosphatidylcholine (DSPC, Avanti Polar Lipids Inc., Alabaster, AL), distearoyl phosphatidylethanolamine-methyl polyethylene glycol (mPEG-DSPE 5 k, Layson Bio Inc., Arab, AL) and DiO (Biotium Inc., CA) in 85:13:2 molar ratio. The gas core of the microbubble consisted of perfluorohexane (Sigma-Aldrich, St. Louis, MO) and air mixture designed to attain stability under atmospheric pressure. Microbubbles were fractionated based on size by their settling time (
Molecular Biology and Transgenic Animals
All C. elegans strains were grown under standard conditions as described (S. Brenner, Genetics 77 (1), 71 (1974)). Cell-selective expression of TRP-4 was achieved by driving the full-length cDNA under odr-3 (AWC), sra-6 (ASH) and des-2 (PVD and FLP) promoters. Germline transformations were obtained using the methods previously described (C. C. Mello, J. M. Kramer, D. Stinchcomb et al., Embo J 10 (12), 3959 (1991)). Complete information for all strains is listed in Table 1.
Temperature Estimation
Ultrasound stimulation in combination with microbubbles has been previously shown to cause temperature changes in the surrounding media (D. Razansky, P. D. Einziger, and D. R. Adam, IEEE Trans Ultrason Ferroelectr Freq Control 53 (1), 137 (2006)). The authors experimentally found a temperature increase of 14.11° C./sec using a continuous 1.1 MHz ultrasound pulse with a peak negative pressure of 2.8 MPa (D. Razansky, P. D. Einziger, and D. R. Adam, IEEE Trans Ultrason Ferroelectr Freq Control 53 (1), 137 (2006)). In Applicants' assays, Applicants used pulses of 10 ms and a maximum peak ultrasound pressure at 0.8 MPa.
Applicants assumed a linear relationship between energy deposition and peak ultrasound pressure and calculated the temperature increase around the worms on the agar surface to be 0.04° C.
Ultrasound and Microscopy Setup
A schematic of the ultrasound and microscopy setup is shown in
White light illumination was achieved by reflecting light from an external light source up at the petri dish using a mirror mounted at 45°. Behavior was captured using a high-speed camera (FASTCAM, Photron, San Diego, CA). Fluorescent images were collected using a Nikon 1-FL EPI-fluorescence attachment on the same setup as described. GCaMP imaging was performed using a 40× objective and the images were captured using a Quanti-EM 512C camera (Photometrics, Tucson, AZ).
The petri dish was held at the air-water interface with a three-prong clamp mounted to an XYZ micromanipulator stage allowing the dish to be scanned in the XY plane, while maintaining a constant Z distance between the objective and ultrasound transducer. This alignment positioned the agar surface in the focal zone of the ultrasound wave.
Claims
1. An imaging and ultrasound exposure system for altering the function of nerve cells that innervate a targeted tissue portion of a mammalian subject, the system comprising an imaging source and an ultrasound source comprising a ultrasound beam focusing transducer; wherein said ultrasound source of the system (i) delivers ultrasound to an exposed surface of the mammalian subject; (ii) provides ultrasound energy to the innervated targeted tissue portion, wherein the nerve cells that innervate the targeted tissue portion are configured to express an ultrasound-sensitive, exogenous TRP-N or TRP-4 transmembrane protein; and (iii) modulates the membrane potential of the nerve cells comprising the targeted tissue structure when the targeted tissue portion of the animal is exposed to ultrasound energy from the ultrasound source.
2. The system of claim 1, wherein the nerve cells are genetically modified to express the exogenous TRP-N transmembrane protein.
3. The system of claim 1, wherein the nerve cells are genetically modified to express the exogenous TRP-4 transmembrane protein.
4. The system of claim 2, wherein the exogenous TRP-N transmembrane protein is a non-mammalian TRP-N transmembrane protein.
5. The system of claim 3, wherein the exogenous TRP-4 transmembrane protein is a non-mammalian TRP-4 transmembrane protein.
6. The system of claim 1, wherein said TRP-4 polypeptide is encoded by a polynucleotide codon-optimized for expression in the cell.
7. The system of claim 1, wherein the exogenous TRP-4 polypeptide comprises an amino acid sequence having at least 85% identity to the amino acid sequence of SEQ ID NO: 1.
8. The system of claim 1, wherein the exogenous TRP-4 polypeptide comprises the amino acid sequence of SEQ ID NO: 1.
9. The system of claim 1, wherein the ultrasound source comprises an ultrasound transducer.
10. The system of claim 1, wherein the nerve cells are motor neurons, sensory neurons, or interneurons.
11. The system of claim 1, wherein the mammalian subject is a human subject.
12. The system of claim 1, wherein the nerve cells are transduced using a vector comprising a polynucleotide sequence encoding the exogenous TRP-N polypeptide or using a recombinant nucleic acid molecule encoding the exogenous TRP-N polypeptide.
13. The system of claim 1, wherein the nerve cells are transduced using a vector comprising a polynucleotide sequence encoding the exogenous TRP-4 polypeptide or using a recombinant nucleic acid molecule encoding the exogenous TRP-4 polypeptide.
14. The system of claim 1, wherein the ultrasound has a frequency of about 0.8 MHz to about 4 MHz.
15. The system of claim 1, wherein said ultrasound has a focal zone of about 1 cubic millimeter to about 1 cubic centimeter.
16. The system of claim 1, wherein the system operates with an ultrasound frequency of at least 20 kHz.
Type: Application
Filed: Aug 31, 2023
Publication Date: Jan 18, 2024
Applicant: Salk Institute for Biological Studies (La Jolla, CA)
Inventors: Sreekanth H. CHALASANI (La Jolla, CA), Stuart IBSEN (La Jolla, CA)
Application Number: 18/459,143
