Transient receptor potential vanilloid channels functioning in transduction of osmotic stimuli

In signal transduction of metazoan cells, ion channels of the family of transient receptor potential (TRP) have been identified to respond to diverse external and internal stimuli, amongst them osmotic stimuli. This review will highlight findings on the TRPV subfamily, both vertebrate and invertebrate members. Out of the six mammalian TRP vanilloid (TRPV) channels, TRPV1, TRPV2, and TRPV4 were demonstrated to function in transduction of osmotic stimuli. TRPV channels have been found to function in cellular as well as systemic osmotic homeostasis in vertebrates. Invertebrate TRPV channels, five in Caenorhabditis elegans and two in Drosophila, have been shown to play a role in mechanosensation, such as hearing and proprioception in Drosophila and nose touch in C. elegans, and in the response to osmotic stimuli in C. elegans. In a striking example of evolutionary conservation of function, mammalian TRPV4 has been found to rescue osmo- and mechanosensory deficits of the TRPV mutant strain osm-9 in C. elegans, despite not more than 26% orthology of the respective proteins.