Pathogenic Mechanism Of Disease-Associated Cx31 Mutants

Gap junctions, consisting of connexins, allow the exchange of small molecules (＜1000 Da) between adjacent cells and provide a mechanism of synchronizing response of groups of cells to environment stimuli.Mutations in connexin 31 [Cx31, also known as gap junction proteinβ-3 (GJB3)] have been linked to disorders of the skin,auditory system and peripheral neuropathy. Different types of GJB3 mutations appear to be associated with specific human disorders,For example, heating impairment-associated GJB3 mutations are distinct from those identified in EKV patients. However, little is known about the molecular basis of the distinct pathogenic processes associated with Cx31 mutants.We hypothesize that Cx31 mutant-associated heating impairment and skin disease are consequences of abnormal metablism of mutant proteins.To examine this hypothesis, we have studied the degradation of Cx31 wild-type ,four hearing impairment-associated Cx31mutants (141delI, I141V, R180X, and E183K) mutants and four EKV-associated Cx31 mutants (G12D, L34P, R42P, and F137L)using Hela cells stably expressing these genes indicidually. Light microscopic analysis showed that both wild-type and mutant Cx31-variants is sensitive to proteasome and lysosome inhibitors. However, western blots analysis revealed difference between EKV-associated Cx31 mutants and wild type or heating impairment-associated Cx31 mutants . Including notable increase in EKV-associated Cx31 mutants in response to MG132 inhibition of proteosome; It is no distinct change in response to all inhibitors for wild type and hearing impairment-associated Cx31 mutants except for R180X-mutant.Interestingly, Aggresome-like juxtanuclear structure had formatted for a longer time under MG132 inhibition of proteosome to EKV-associated Cx31 mutants ,And which is certified by these characteristic features①redistribution of the intermediate filament protein vimentin to form a cage surrounding a pericentriolar core of aggregated,②these aggregates are positive on ubiquitin and cellular chaperones(Hsp70c)③disruption of microtubules blocks the formation of aggresomes-like.Dominant EKV-associated Cx31 mutants can formate functional gap junction by which is dealed with cold sholk or chemical chaperones. Together, our data suggests that abnormal degradation and aggresome formation are linked to the pathogenesis of the EKV-associated Cx31 mutants.