Bai Li, Yu Zu-Bin, Qian Pin, Qian Gui-Sheng, Guan Song, Li Shu-Ping
Institute of Respiratory Diseases, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
Zhonghua Nei Ke Za Zhi. 2005 Jan;44(1):42-5.
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.
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.
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).
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.
探讨细胞因子信号转导抑制因子（SOCS）3基因对缺氧状态下大鼠肺动脉平滑肌细胞（PASMCs）中c-fos、c-jun mRNA表达及细胞增殖的影响。
采用脂质体介导将pEFSOCS3和pSV2neo共转染至PASMCs，通过免疫细胞化学检测SOCS3蛋白表达。分别将PASMCs在常氧和缺氧条件下暴露不同时间点后，采用半定量RT-PCR检测c-fos和c-jun mRNA表达。运用流式细胞术DNA分析检测细胞周期。
经Western blot证实，转染SOCS3基因的PASMCs中有SOCS3蛋白表达。对照细胞中c-fos mRNA水平在缺氧2 h时达到峰值，4 h时下降，随后在8 h再次达到峰值，12 h时下降。在缺氧2 h和8 h时，转染SOCS3基因的细胞中c-fos mRNA水平分别低于同一时间点的对照细胞（P < 0.01）。对照细胞在缺氧2 h后c-jun mRNA水平升高，在缺氧6 h时达到峰值，12 h时降至基础水平。在缺氧2 h、4 h、6 h、8 h时，转染SOCS3基因的细胞中c-jun mRNA水平低于同一时间点的对照细胞。与对照PASMCs相比，在常氧和缺氧条件下，转染SOCS3基因的细胞处于G(1)/G(0)期的增加，处于S + G(2)/M期的减少（P < 0.01）。
缺氧诱导c-fos和c-jun基因表达，这可能在PASMCs增殖早期起重要作用。SOCS3蛋白可能通过降低缺氧状态下STAT3蛋白的酪氨酸磷酸化水平来抑制PASMCs的增殖。
