Abstract: In aspects, the invention provides a polypeptide construct comprising (a) a first polypeptide comprising an amino acid sequence derived from a basic helix of a transcription factor protein that comprises a basic helix-loop-helix domain; and (b) a second polypeptide comprising an amino acid sequence derived from a helix that extends in the C-terminal direction from the end of the loop of a basic helix-loop-helix domain of a transcription factor protein that comprises a basic helix-loop-helix domain; wherein the first polypeptide and the second polypeptide are linked through an interpolypeptide covalent linkage. Additional aspects of the invention are as described herein.