The deaf jerker mouse has a mutation in the gene encoding the espin actin-bundling proteins of hair cell stereocilia and lacks espins

The espins are actin-bundling proteins of brush border microvilli and Serto li cell-spermatid junctions. We have determined that espins are also presen t in hair cell stereocilia and have uncovered a connection between the espi n gene and jerker, a recessive mutation that causes hair cell degeneration, deafness, and vestibular dysfunction. The espin gene maps to the same regi on of mouse chromosome 4 as jerker. The tissues of jerker mice do not accum ulate espin proteins but contain normal levels of espin mRNAs. The espin ge ne of jerker mice has a frameshift mutation that affects the espin C-termin al actin-bundling module. These data suggest that jerker mice are, in effec t, espin null and that the jerker phenotype results from a mutation in the espin gene.