科研之友
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摘要
Aims: This study aimed to explore the precise mechanism and signaling pathways of mesangial cell (MC) proliferation from a new point of view considering Connexin 43 (Cx43). Methods: MC proliferation was measured by the incorporation of 3H-thymidine (3H-TdR). Cx43 was over-expressed in MC cells using lipofectamine 2000, and the expression level was tested with reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analyses. The gap junction channel function was explored by Lucifer Yellow scrape loading and dye transfer (SLDT), and the intracellular calcium concentrations ([Ca2+](i)) were characterized by confocal microscopy on cells loaded with Fura-3/AM. Results: There was an inverse correlation between Cx43 expression and MC proliferation (P < 0.05). SLDT studies revealed that there was no difference in the gap junction channel function between the normal and Aldosterone (Aldo)stimulated groups (P > 0.05). Our data also showed that the mineralcorticoid receptor (MR) antagonist spironolactone, ERK1/2 inhibitor PD98059 and PKC inhibitor GF109203X could attenuate the down-regulation of Cx43 expression in Aldo-induced MC proliferation; however, the PI3K inhibitor LY294002 could block MC proliferation without affecting Cx43 expression at either the mRNA or protein level. In addition, Aldo promoted MC proliferation in parallel with increasing [Ca2+](i) (P < 0.05), suggesting that the classical PKC pathway might be activated. Conclusions: Our study provides preliminary evidence that Cx43 is an important regulator of Aldo-promoted MC proliferation. Furthermore, reduced Cx43 expression promoted MC proliferation independent of the gap junction channel function, and this process might be mediated through the ERK1/2- and PKC-dependent pathways.
