Appearance and distribution of the 275 kD hair‐cell antigen during development of the avian inner ear

Abstract

The 275 kD hair-cell antigen (HCA) is a protein that was originally identified using immunological techniques in the inner ears of early hatchling and adult chickens. The HCA is specifically associated with the apical surface of sensory hair cells; in the vestibular system the antigen is distributed over the entire stereocilia bundle, but in the auditory system it only extends a short distance up the shafts of the stereocilia. The objectives of this study were to ascertain when the HCA is first expressed during inner ear development, to compare the temporal and spatial patterns of HCA expression with those of neurite ingrowth, and to determine how the distribution of the antigen observed in the auditory system arises during development. Serial sections of otocysts from embryonic day (ED) 4 to ED7.5 (stages 24 to 32) were stained with a monoclonal antibody to the HCA and polyclonal antibodies to the neuron-glial cell adhesion molecule in order to analyse patterns of HCA expression and neurite ingrowth. Nerve fibres are first observed in the anterior pole of the otocyst at ED4.5 (stage 24), and in the evaginating basilar papilla by ED5 (stage 26). The HCA first appears within the vestibular system in the anterior pole of the otocyst at ED5 (stage 26), and within the auditory system in the distal end of the basilar papilla at ED6.5 (stage 29). Serial section analysis indicates that expression of the HCA is always limited to areas of the epithelium where nerve fibres are found, although the delay between the onset of innervation and the onset of HCA expression varies from one region of the otocyst to another. The growth of stereocilia bundles in the auditory system was studied from ED10 to 2 days after hatching in sections from the medial to distal regions of the basilar papilla double labelled with rhodamine phalloidin and monoclonal anti-HCA. At ED12 the stereocilia bundles are 1.7 microns high and the staining observed with both phalloidin and the antibody extend to the same maximum height above the apical surface of the hair cell. The maximum height that anti-HCA staining extends up the stereocilia bundle remains almost constant between ED12 and postnatal day 2, but between ED15 and ED18 the stereocilia bundle grows rapidly in height, with a membrane domain lacking the HCA forming at the distal ends of the stereocilia.(ABSTRACT TRUNCATED AT 400 WORDS)

Supporting Cell Division Is Not Required for Regeneration of Auditory Hair Cells After Ototoxic Injury In Vitro

“…This latter measure has been shown to reflect differentiation of mechanotransduction by HCs in other studies (Géléoc and Holt 2003;Si et al 2003). In 10-day cultures treated with aphidicolin, many myosinVI-positive cells had begun to develop bundles of stereocilia, as reflected by colabeling for HCA (Bartolami et al 1991; Fig. 11E, F).…”

“…HCA is a glycoprotein present in developing and mature stereociliary bundles of avian HCs (Bartolami et al 1991). It is expressed at a later stage of differentiation during in vivo regeneration than myosinVI (Stone and Rubel 2000).…”

DAN directs endolymphatic sac and duct outgrowth in the avian inner ear

“…To analyze the effects of DAN on otic sensory epithelium, inner ears exposed to DAN were examined by using the hair cell-specific antibody HCA (Bartolami et al, 1991;Goodyear and Richardson, 1992). Hair cell antigen distribution was unaltered in unoperated control inner ears as previously described (Fig.…”

“…The ears were stained in a 1:1,000 dilution of an antibody specific for a 275-kDa HCA kindly provided by Dr. Guy Richardson, Sussex University (Bartolami et al, 1991;Goodyear and Richardson, 1992) and post-fixed in 4% paraformaldehyde.…”

Bone marrow mesenchymal stem cells are progenitors in vitro for inner ear hair cells

“…One possible explanation for the expression of hair cell genes by the MSC-derived cells in co-culture is fusion with chick cells. To rule this out we labeled the cells with an antibody to chick hair cell antigen (Bartolami et al, 1991). Native chick hair cells could be detected lining the internal cavity of the otocyst (51% of 1,352 cells from 15 otocyst injections that stained for myosin VIIa were positive for chick hair cell antigen), and the cells that expressed nGFP and hair cell markers did not co-express chick hair cell antigen (Fig.…”