CONNEXIN 43 EXPRESSION IN THE HUMAN COCHLEA: AN IMMUNOHISTOCHEMISTRY STUDY

Abstract

BackgroundMutations in the gene GJA1 which encodes gap junction protein connexin 43 (Cx43) have been linked to nonsyndromic prelingual deafness in humans. The protein forms gap junction channels (GJChs), creating intercellular pathways for ions and small molecules – such as second messengers (IP3, cAMP, cGMP, and others), diverse metabolites (e.g. glucose, amino acids, glutathione, ATP) and neuroprotectant (e.g. adenosine) – to reach neighboring cells. Cx43 in glial cells of the central nervous system (CNS) and in satellite glial cells of the peripheral nociceptive sensory ganglia has been studied for its structure as well as function in signal transduction and neuron protection. Distribution of Cx43 in the human cochlea is an important unresolved issue.Material and MethodsFor the first time we analysed, using immunofluorescence and confocal immunofluorescence, the expression and distribution of Cx43 in 5 normal fresh human cochleae obtained at surgery for removal of giant posterior cranial fossa meningioma.ResultsIn the lateral wall of the cochlea, Cx43 was expressed mainly in the basal cell layer of the stria vascularis and the fibrocytes of the spiral ligament. In the organ of Corti, Cx43 antibody strongly stained both inner and outer pillar cells, the covering layer cells of the basilar membrane and the supporting cells underneath outer hair cells. In the spiral ganglion, Cx43 expression was located in the satellite glial cells (SGCs) surrounding type I neurons.ConclusionsCx43 expression was found in human cochleae including the lateral wall, organ of Corti and spiral ganglion satellite cells. Potential roles played by GJChs built up by Cx43 in maintaining homeostasis of the cochlea and protection of neurons are speculated.