A Dominant Loss-of-Function GJA1 (Cx43) Mutant Impairs Parturition in the Mouse1

Abstract

Expression of GJA1 (commonly known as connexin43 or Cx43), a major myometrial gap junction protein, is upregulated before the onset of delivery, suggesting an essential role for Cx43-mediated gap junctional intercellular communication (GJIC) in normal uterine contraction during parturition. To determine how a disease-linked Cx43 mutation affects myometrial function, we studied a mutant mouse model carrying an autosomal dominant mutation (Gja1^Jrt) in the gene encoding Cx43 that displays features of the human genetic disease oculodentodigital dysplasia. We found that Cx43 level, specifically the phosphorylated species of the protein, is significantly reduced in the myometrium of the mutant mice (Gja1^Jrt/+), as revealed by Western blotting and immunostaining. Patch-clamp electrophysiological measurements demonstrated that coupling between myometrial smooth muscle cells is reduced to Gja1^Jrt mutation has a dominant-negative effect on Cx43 function in the myometrium, severely reducing GJIC, leading to impaired parturition.