Ling S, Dai A, Ma Y H, Wilson E, Chatterjee K, Ives H E, Sudhir K
Divisions of Nephrology and Cardiology, Cardiovascular Research Institute, University of California, San Francisco, USA.
Hypertension. 1999 Nov;34(5):1141-6. doi: 10.1161/01.hyp.34.5.1141.
We have previously shown, in a neonatal rat cell line, that angiotensin II (Ang II)-induced proliferation in vascular smooth muscle cells is extracellular matrix (ECM) dependent. We hypothesized that such an effect might be mediated via differences in Ang II-induced increases in the transcriptional factor early growth response-1 (Egr-1) gene and, consequently, in platelet-derived growth factor (PDGF). Cultured human newborn aortic smooth muscle cells were studied on 4 different surfaces: (1) plastic, (2) laminin, (3) collagen, and (4) fibronectin. Ang II-induced increases in DNA synthesis were significantly greater on collagen (2.0+/-0.3-fold) and fibronectin (1.9+/-0.3-fold) than on laminin (1.0+/-0.2-fold) or plastic (1.4+/-0.2-fold). As with DNA synthesis, at 48 and 72 hours, Ang II-induced increases in cell numbers occurred only in cells grown on collagen and fibronectin culture plates and were blocked by an antagonist to the angiotensin type 1 (losartan, 10 micromol/L) but not the angiotensin type 2 (PD 123319, 10 micromol/L) receptor. Anti-PDGF AA antibody (6 microg/mL) blocked the increase in DNA synthesis by 60% to 64% in cells on collagen or fibronectin cultures but not on plastic cultures. When PDGF-AA (10 ng/mL) and Ang II were added together, DNA synthesis increased 2-fold and did not differ on the various ECM proteins. Increases in PDGF A-chain mRNA were observed only in cells grown on collagen (3.21+/-0.65-fold) and fibronectin (2.86+/-0.49-fold) plates 2 to 8 hours after the addition of Ang II and were blocked by losartan but not PD 123319. Expression of Egr-1, an early growth response gene, increased at 15 minutes, peaked at 30 minutes, and returned to normal after 2 hours with Ang II treatment. Ang II-induced increases in Egr-1 mRNA were greater on collagen (4. 82+/-0.66-fold at maximum) and fibronectin (4.01+/-0.56-fold) than on laminin (2.74+/-0.45-fold) or plastic (2.53+/-0.40-fold) and were blocked by losartan but not PD 123319. Thus, in human vascular smooth muscle cells in culture, Ang II-induced proliferation is mediated via the angiotensin type 1 receptor, dependent on ECM proteins, and regulated by differential gene expression of Egr-1 and PDGF-1.
我们之前在新生大鼠细胞系中已经表明，血管紧张素II（Ang II）诱导的血管平滑肌细胞增殖依赖于细胞外基质（ECM）。我们推测，这种效应可能是通过Ang II诱导的转录因子早期生长反应-1（Egr-1）基因增加以及血小板衍生生长因子（PDGF）的差异介导的。在4种不同表面上研究了培养的人类新生儿主动脉平滑肌细胞：（1）塑料，（2）层粘连蛋白，（3）胶原蛋白，（4）纤连蛋白。与层粘连蛋白（1.0±0.2倍）或塑料（1.4±0.2倍）相比，Ang II诱导的胶原蛋白（2.0±0.3倍）和纤连蛋白（1.9±0.3倍）上的DNA合成增加显著更大。与DNA合成一样，在48和72小时时，Ang II诱导的细胞数量增加仅发生在胶原蛋白和纤连蛋白培养板上生长的细胞中，并被血管紧张素1型拮抗剂（氯沙坦，10 μmol/L）阻断，但未被血管紧张素2型（PD 123319，10 μmol/L）受体阻断。抗PDGF AA抗体（6 μg/mL）在胶原蛋白或纤连蛋白培养的细胞中使DNA合成增加减少60%至64%，但在塑料培养的细胞中没有。当同时添加PDGF-AA（10 ng/mL）和Ang II时，DNA合成增加2倍，并且在各种ECM蛋白上没有差异。仅在添加Ang II后2至8小时在胶原蛋白（3.21±0.65倍）和纤连蛋白（2.86±0.49倍）培养板上生长的细胞中观察到PDGF A链mRNA增加，并被氯沙坦阻断，但未被PD 123319阻断。早期生长反应基因Egr-1的表达在15分钟时增加，在30分钟时达到峰值，并在Ang II处理2小时后恢复正常。Ang II诱导的Egr-1 mRNA增加在胶原蛋白（最大4.82±0.66倍）和纤连蛋白（4.01±0.56倍）上比在层粘连蛋白（2.74±0.45倍）或塑料（2.53±0.40倍）上更大，并被氯沙坦阻断，但未被PD 123319阻断。因此，在培养的人类血管平滑肌细胞中，Ang II诱导的增殖通过血管紧张素1型受体介导，依赖于ECM蛋白，并由Egr-1和PDGF-1的差异基因表达调节。
