Abstract: Provided herein are a variety of molecular feed-forward circuits. In some embodiments a molecular feed-forward circuit may comprise a first nucleic acid comprising a first nucleotide sequence encoding a regulatory protein that is activated by a first exogenous stimulus, and a second nucleic acid comprising a second nucleotide sequence encoding a signaling protein that is activated by the first exogenous stimulus, where the target protein has a regulatory motif and the activated regulatory protein inactivates the target protein via the regulatory motif. The molecular circuit can further comprise a controller protein that is activated by a second exogenous signal, wherein the controller protein controls the interaction between the regulatory protein and the target protein. In this circuit activation of the regulatory protein is delayed relative to the activation of the target protein. The system can be used to produce a pulse of signaling and/or a concentration filter, for example.