Connexin 26 distribution in gap junctions between melanocytes in the human vestibular dark cell area

Abstract

We have previously demonstrated the presence of gap junctions between melanocytes in the human vestibular organ and have speculated that melanocytes function in maintaining the homeostasis of the microenvironment of the inner ear. The purpose of the present study was to characterize the expression and ultrastructural localization of connexin (Cx) protein in melanocytes of the human vestibular organs. Surgical material was obtained from patients operated on for vestibular schwannoma and was processed for light microscopy, confocal laser scanning microscopy, conventional TEM, and immuno TEM. The specimens were labeled with anti‐Cx26, Cx32, and Cx43 antibodies and examined by light microscopy. Specimens were also labeled with anti‐Cx26 antibody and examined by laser microscopy and immuno‐TEM methods. The specimens examined in this study were mainly dark cell areas from the human vestibular organ, whose epithelial and subepithelial layers are rich in melanocytes. Light‐microscopic immunohistochemical studies showed positive labeling for Cx26 protein between subepithelial melanocytes, and Cx32 was also detected. Use of anti‐Cx26 antibody and confocal laser scanning microscopy revealed high levels of Cx26 around the subepithelial melanocytes. Post‐embedding immuno‐gold transmission electron microscopy showed significant aggregation of gold particles (33.97 ± 8.01% of total gold particles) around the gap junctions of the subepithelial melanocytes. The results of this study indicated that melanocytes are connected through gap junctions that mainly contain Cx26. This suggested that the melanocytes in the human vestibular organ may play a role in transporting material between the endolymph and perilymph. Anat Rec 262:137–146, 2001. © 2001 Wiley‐Liss, Inc.

Sudden sensorineural hearing loss: Is there a connection with inner ear electrolytic disorders? A literature review

“…18 This system plays an important role in the transport of metabolites and electrolytes, Na + / K + mainly, between the inner-ear endolymph and perilymph. 19 A specific damage to this delicate structure (i.e. the absence of melanocytes-like macrophages) has been reported to increase vessels permeability through an alteration of the tight junctions with a reduction of the endocochlear potential by altering the Na + -K + ATPase activity, therefore causing hearing impairment, as indicated in experiences with melanocytes-deficient mutant rats.…”

“…17 The blood-labyrinth barrier is important not only to prevent the influx of toxic substances into the inner ear, but also for inner-ear homeostasis itself. 18,19 It is composed of endothelial cells (connected to each other by tight junctions 20 ), an underlying basement membrane, a large number of pericytes, 21 and perivascular resident macrophages. 18 This system plays an important role in the transport of metabolites and electrolytes, Na + / K + mainly, between the inner-ear endolymph and perilymph.…”

Connexin43 Reduces Melanoma Growth within a Keratinocyte Microenvironment and during Tumorigenesis in Vivo

“…Although the connexin family is large, most evidence suggests that the two prominent connexins in melanocytes are Cx26 and Cx43, which enables GJIC with keratinocytes (4,5). This direct cell to cell communication is often lost during melanoma transformation, which appears to be due to connexin down-regulation (4,23).…”

“…Primarily, these connexins are expressed by keratinocytes and are differentially regulated within the different epidermal strata (3). Additionally, melanocytes, which reside in the basal layer of the epidermis, have been reported to only express Cx26 and Cx43 (4,5). Typically, one melanocyte forms contacts with ϳ30 keratinocytes within the basal and suprabasal layers forming the "epidermal-melanin unit" (6), and the connexin compatibilities of the two cell types render them capable of heterocellular GJIC (4).…”

Melanomas melânicos e amelânicos da cavidade bucal de cães: aspectos epidemiológicos, morfológicos e moleculares

“…A mutação do gene da conexina 26 não se restringe apenas as lesões de pele, mas também a problemas relacionados à audição (KELLSELL et al, 1997) (MASUDA et al, 1996). Haja vista que esta proteína esteja presente em diversos tecidos humanos, tais como cérebro, fígado, rim e esôfago, podendo também ser encontrada entre os melanócitos subepiteliais (MASUDA et al, 2001). …”