The invention provides compositions and methods for regulating intracellular osmolarity in cells, e.g., in cultured cells, including in cultured cells in bioreactors. The invention provides nucleic acids comprising at least one osmo-responsive transcriptional regulatory element (OR-TRE), and cells, vectors, products of manufacture, artificial organs or implants and the like containing an osmo-responsive transcriptional regulatory element (OR-TRE).