[Effects of cytokine signaling 3 suppressors gene on c-fos and c-jun mRNA expression and proliferation of pulmonary arterial smooth muscle cells in rat under hypoxia].

OBJECTIVE

To explore the effects of suppressors of cytokine signaling (SOCS)3 gene on expression of c-fos, c-jun mRNA and proliferation of rat pulmonary arterial smooth muscle cells(PASMCs) under hypoxia.

METHODS

PASMCs were co-transfected with pEFSOCS3 and pSV2neo by liposome, and then expression of SOCS3 protein was detected by immunocytochemistry. After PASMCs were exposed to normoxic and hypoxia at various time points respectively, expression of c-fos and c-jun mRNA was assessed by semi-quantitive RT-PCR. Flow cytometric DNA analysis was used to detect cell cycles.

RESULTS

Expression of SOCS3 protein was confirmed by Western blot in PASMCs transfected with SOCS3 gene. The c-fos mRNA level in control cells peaked at 2 h of hypoxia and declined at 4 h, then peaked at 8 h secondly and declined at 12 h. C-fos mRNA level in SOCS3 gene-transfected cells at 2 h and 8 h exposed to hypoxia was lower than that in control cells at the same time points respectively (P < 0.01). The c-jun mRNA level increased at 2 h after exposure of control cells to hypoxia, peaked at 6 h of hypoxia and declined to the basal levels at 12 h. C-jun mRNA level of SOCS3 gene-transfected cells at 2 h, 4 h, 6 h, 8 h under hypoxia was lower than that in controls cells at the same time points. Compared with control PASMCs, cells in transfected with SOCS3 gene at G(1)/G(0) phase increased and those at S + G(2)/M phase decreased under normoxic and hypoxia (P < 0.01).

CONCLUSION

Hypoxia induced expression of c-fos and c-jun genes, which might play an vital role in the early stage of PASMCs proliferation. SOCS3 protein may inhibit proliferation of PASMCs by lowering the tyrosine-phosphorylated level of STAT3 protein under hypoxia.