Stomatin, a MEC-5 like protein, is expressed by mammalian sensory neurons

The molecular mechanism whereby vertebrate primary sensory neurons convert mechanical energy at their receptive fields into action potentials is unkno wn. In recent years, genetic screens for touch insensitive mutants of the n ematode worm Caenorhabditis elegans have led to the identification of sever al genes required for mechanical sensitivity. A model has been proposed in which a mechanically gated ion channel is connected both to the extracellul ar matrix and to the cytoskeleton. Displacement of the membrane is proposed to produce a shearing force that pulls the channel open. MEC-2 is thought to play an important role in this complex by linking the ion channel to the cytoskeleton. MEC-2 is highly homologous to a vertebrate protein called st omatin. Stomatin was first isolated from erythrocytes where it is a major i ntegral membrane protein. To date, however, no data on neuronal expression of stomatin in the peripheral nervous system (PNS) or central nervous syste m (CNS) is available. Here, we have used RT-PCR, in situ hybridization, Nor thern blotting, and immunocytochemistry to demonstrate that stomatin is exp ressed by all sensory neurons in mouse dorsal root ganglia. Indirect immuno fluorescence together with transfection of cultured adult sensory neurons w ith epitope-tagged stomatin show that stomatin is localized in spots on som atic and axonal membranes. During development, stomatin begins to be expres sed by sensory neurons only as target innervation occurs. The onset of expr ession of stomatin thus coincides with the onset of functional mechanical s ensitivity. Together, our data suggest that stomatin, like the C. elegans M EC-5 gene, is expressed in an appropriate temporal and spatial manner to pa rticipate in a putative vertebrate mechanotransduction complex.