Submitted on March 9, 2005
Accepted on October 11, 2005
Opposite regulation of connexin33 and connexin43 by LPS and IL-1
in spermatogenesis
Celine Fiorini1, Xavier Decrouy2, Norah Defamie1, Dominique Segretain2, and Georges Pointis1*
1 Faculty of Medecine, INSERM U 670, Nice, none, France
2 University Paris V, INSERM U 670, Paris, none, France
* To whom correspondence should be addressed. E-mail: pointis{at}unice.fr.
The gap junction proteins, connexins (Cxs), are present in the testis and among them Cx43 play an essential role in spermatogenesis. The present study investigated the testicular expression and regulation of another Cx, Cx33, previously described as a negative regulator of gap junction communication. Cx33 mRNA, was present in testis and undetectable in heart, liver, ovary and uterus. In the mature testis, Cx33 was specifically immunolocalized in the basal compartment of the seminiferous tubules whereas Cx43 was present in both seminiferous tubule and interstitial compartments. During stages IX-X of spermatogenesis, characterized by Sertoli cell phagocytosis of residual bodies, Cx43 was poorly expressed within seminiferous tubules while Cx33 signal was strong. In order to evaluate the role of phagocytosis in the control of Cx33 and Cx43 expressions, the effect of lipopolysaccharides (LPS) was analyzed on the Sertoli cell line 42GPA9. We show that phagocytosis activation by LPS concomitantly stimulated Cx33 and inhibited Cx43 mRNA levels. These effects appear mediated through IL-1
since the exposure of Sertoli cells to the IL-1 receptor antagonist partly reversed these effects. IL-1 enhanced and reduced respectively the levels of Cx33 and Cx43 mRNA in a time- and dose-dependent manner. These data reveal that Cx33 and Cx43 genes are differently controlled within the testis and suggest that these two Cxs may exert opposite and complementary effects on spermatogenesis.
