串珠素表达下调参与低氧对大鼠心肌微血管内皮细胞增殖的抑制作用

Down-regulation of perlecan expression contributes to the inhibition of rat cardiac microvascular endothelial cell proliferation induced by hypoxia

低氧可以抑制内皮细胞增殖,但是其机理目前尚不清楚。串珠素在调节内皮细胞增殖中发挥着重要作用。为了探讨串珠素是否参与低氧对内皮细胞增殖的抑制,将大鼠心肌微血管内皮细胞在低氧或常氧状态下培养12 h后,用实时定量RT-PCR方法检测串珠素mRNA的表达。结果发现:低氧可以明显抑制串珠素mRNA的表达,与常氧状态下串珠素mRNA表达水平比较,差异显著(P<0．05)。与此同时,低氧状态下或用串珠素抗体中和内源性串珠素,内皮细胞的增殖和对成纤维细胞生长因子的反应明显降低,粘着斑激酶(focal adhesion kinase,FAK)表达和细胞外信号调节激酶1／2(extracellular signal- regulated kinase,ERK1／2)活性明显下降。结果提示,串珠素表达下调可能通过抑制FAK介导的ERK1/2依赖的信号转导途径,参与低氧对大鼠心肌微血管内皮细胞增殖的抑制作用。

Exposure of endothelial cells （ECs） to hypoxia leads to a decrease in EC proliferation. However, the mechanism by which hypoxia inhibits EC proliferation is unclear. Perlecan has been reported to play an important role in regulating EC proliferation. We hypothesized that perlecan was involved in the hypoxia-induced inhibition of EC proliferation. To test this hypothesis, rat cardiac microvascular ECs were cultured under normoxic or hypoxic conditions for 12 h and harvested for determination of perlecan mRNA expression using real-time reverse transcription-polymerase chain reaction （RT-PCR）. The results showed that exposure of ECs to hypoxia for 12 h induced a decrease in perlecan mRNA expression （61.72%, P〈0.05）. Concomitantly, the down-regulation of endo- genous perlecan induced by hypoxia or the neutralization of endogenous perlecan with anti-perlecan antibody significantly inhibited EC proliferation and responsiveness to basic fibroblast growth factor （bFGF）, and decreased focal adhesion kinase （FAK） expression and extracellular signal-regulated kinase 1/2 （ERKI/2） activation. These data indicate that down-regulation of perlecan expression contributes to hypoxia-induced inhibition of rat cardiac microvascular EC proliferation by suppressing FAK-mediated and ERK 1/2- dependent growth signals.