Department of Surgery, Division of Vascular Surgery, VA Puget Sound Health Care System and The University of Washington School of Medicine, Seattle, WA, USA.
Department of Surgery, Division of Vascular Surgery, VA Puget Sound Health Care System and The University of Washington School of Medicine, Seattle, WA, USA.
Atherosclerosis. 2014 May;234(1):169-75. doi: 10.1016/j.atherosclerosis.2014.02.029. Epub 2014 Mar 11.
Smooth muscle cell (SMC) de-differentiation is a key step that leads to pathological narrowing of blood vessels. De-differentiation involves a reduction in the expression of the SMC contractile genes that are the hallmark of quiescent SMCs. While there is considerable evidence linking inflammation to vascular diseases, very little is known about the mechanisms by which inflammatory signals lead to SMC de-differentiation. Given that the Signal Transducers and Activators of Transcription (STAT) transcriptional factors are the key signaling molecules activated by many inflammatory cytokines and growth factors, the aim of the present study was to determine if STAT transcriptional factors play a role SMC de-differentiation.
Using shRNA targeted to STAT-1 and STAT-3, we show by real time RT-PCR and Western immunoblots that STAT-1 significantly reduces SMC contractile gene expression. In contrast, STAT-3 promotes expression of SMC contractile genes. Over-expression studies of STAT-1 and STAT-3 confirmed our observation that STAT-1 down-regulates whereas STAT-3 promotes SMC contractile gene expression. Bioinformatics analysis shows that promoters of all SMC contractile genes contain STAT binding sites. Finally, using ChIP analysis, we show that both STAT-1 and STAT-3 associate with the calponin gene.
These data indicate that the balance of STAT-1 and STAT-3 influences the differentiation status of SMCs. Increased levels of STAT-1 promote SMC de-differentiation, whereas high levels of STAT-3 drive SMC into a more mature phenotype. Thus, inhibition of STAT-1 may represent a novel target for therapeutic intervention in the control of vascular diseases such as atherosclerosis and restenosis.
平滑肌细胞（SMC）去分化是导致血管病理性狭窄的关键步骤。去分化涉及到 SMC 收缩基因表达的减少，这些基因是静息 SMC 的标志。虽然有大量证据表明炎症与血管疾病有关，但对于炎症信号如何导致 SMC 去分化的机制知之甚少。鉴于信号转导和转录激活因子（STAT）转录因子是许多炎症细胞因子和生长因子激活的关键信号分子，本研究旨在确定 STAT 转录因子是否在 SMC 去分化中发挥作用。
通过靶向 STAT-1 和 STAT-3 的 shRNA，我们通过实时 RT-PCR 和 Western 免疫印迹显示 STAT-1 显著降低了 SMC 收缩基因的表达。相比之下，STAT-3 促进了 SMC 收缩基因的表达。STAT-1 和 STAT-3 的过表达研究证实了我们的观察结果，即 STAT-1 下调而 STAT-3 促进 SMC 收缩基因的表达。生物信息学分析表明，所有 SMC 收缩基因的启动子都含有 STAT 结合位点。最后，通过 ChIP 分析，我们表明 STAT-1 和 STAT-3 都与钙调蛋白基因结合。
这些数据表明 STAT-1 和 STAT-3 的平衡影响 SMC 的分化状态。STAT-1 水平升高促进 SMC 去分化，而 STAT-3 水平升高则促使 SMC 向更成熟的表型分化。因此，抑制 STAT-1 可能成为治疗动脉粥样硬化和再狭窄等血管疾病的新靶点。
