The calcium-binding protein VILIP in olfactory neurons: regulation of second messenger signaling.

Visinin-like-protein (VILIP), a member of the neuronal subfamily of EF-hand calcium-sensor proteins is shown to be expressed in olfactory sensory cells of the rat nasal epithelium. Its prominent localization in cilia and dendritic knobs-the chemosensory compartments of olfactory neurons-suggests that the calcium-binding protein could be involved in olfactory signal transduction. Consistent with this assumption, it was found that recombinant VILIP attenuates in a calcium-dependent manner odorant-induced cAMP formation in olfactory cilia preparations. Kinetic data indicate that VILIP does not interfere with odorant-induced receptor desensitization. Since VILIP inhibits the forskolin-induced formation of cAMP, it is conceivable that VILIP may directly affect the olfactory adenylyl cyclase. Thus, VILIP may play a role in adaptation of olfactory neurons.