Disease relevance of ESPN

• A recessive mutation of ESPN is known to cause hearing loss and vestibular dysfunction in the jerker mouse [1].

High impact information on ESPN

• Many of the mutations known to cause either syndromic or nonsyndromic deafness occur in genes that interact with actin (e.g., the myosins, espin, and harmonin) [2].
• When expressed by transfected NRK fibroblasts, the same C-terminal fragment of espin was observed to decorate actin fibers or cables [3].
• By immunogold electron microscopy, espin was localized to the parallel actin bundles of ectoplasmic specializations at sites where Sertoli cells contacted the heads of elongate spermatids [3].
• Certain espin isoforms can also bind phosphatidylinositol 4,5-bisphosphate, profilins or SH3 proteins [4].
• Intense espin immunolabeling of stereocilia was colocalized with actin filament staining in all types of hair cells at all developmental stages and in adult animals [5].

Biological context of ESPN

• The abnormal vestibular phenotype associated with ESPN mutations will be a useful clinical marker for refining the differential diagnosis of non-syndromic deafness [1].
• This phenotype co-segregates with either of two frameshift mutations, 1988delAGAG and 2469delGTCA, in ESPN, which encodes a calcium-insensitive actin-bundling protein called espin [1].
• We mapped a human deafness locus DFNB36 to chromosome 1p36.3 in two consanguineous families segregating recessively inherited deafness and vestibular areflexia [1].

Anatomical context of ESPN

• We found that the onset of espin expression correlates with the initiation and growth of stereocilia bundles in vestibular and cochlear hair cells [5].
• Our study was undertaken to investigate the appearance and developmental expression of espin in chicken inner ear sensory epithelia [5].
• Espin cytoskeletal proteins in the sensory cells of rodent taste buds [6].
• We propose that the espin-positive zone in the taste pit coincides with actin bundles in association with the microvilli of type II taste cells, whereas the espin-positive microvilli in the taste pore are the single microvilli of type III taste cells [6].
• We have determined that, in rats and mice, affinity purified espin antibody intensely labels the lingual and palatal taste buds of the oral cavity and taste buds in the pharyngo-laryngeal region [6].

Analytical, diagnostic and therapeutic context of ESPN

• On the basis of results obtained using an antigen-retrieval method in conjunction with double immunofluorescence for espin and sensory taste cell-specific markers, we propose that espins are expressed predominantly in the sensory cells of taste buds [6].

References