Similarities and differences in smooth muscle α-actin induction by TGF-β in smooth muscle versus non-smooth muscle cells
Similarities and differences in smooth muscle α-actin induction by TGF-β in smooth muscle versus non-smooth muscle cells
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DOI：
10.1161/01.atv.19.9.2049
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发表时间：
1999-09-01
影响因子：
8.7
通讯作者：
Owens, GK
中科院分区：
文献类型：
--
作者：
Hautmann, MB;Adam, PJ;Owens, GK
转化生长因子-β（TCF-β）已显示刺激平滑肌细胞（SMC）和非SMC中的平滑肌（SM）α-肌动蛋白表达。我们以前证明了2个CArG盒A和B以及位于SM α-肌动蛋白启动子前125 bp内的新型TGF-β控制元件（TCE）是SMC中SM α-肌动蛋白的TGF-β诱导所必需的。本研究的目的是（1）确定TCE是否具有SMC特异性或有助于TGF-β诱导非SMC中SM α-肌动蛋白表达（即内皮细胞和成纤维细胞）和（2）确定TGF-β是否能诱导多种含TCE的SMC分化标志物基因的表达，如SM 22 α，h（1），钙调蛋白，瞬时转染实验的结果表明，在125 bp启动子范围内的CArG A、CArG B或TCE突变完全消除了内皮细胞和成纤维细胞中SM α-肌动蛋白的TGF-β诱导。然而，与SMC中的观察结果相反，在非SMC中包含-155上游区域完全抑制了TGF-β反应。电泳迁移率变动分析表明，TGF-β增强了血清反应因子与CArG元件的结合，以及一种尚未鉴定的因子与内皮细胞和成纤维细胞中TCE的结合，但与SMC相比，TGF-β在很小程度上也刺激了非SMC中SMC分化标记物SM 22 α的表达。然而，与SMC相反，TGF-β在非SMC中不诱导h（1）、calponin和SM MHC的表达。总之，这些结果表明CArG A、CArG B和TCE在SMC和非SMC中TGF-β诱导的SM α-肌动蛋白表达中的保守作用，其通过正作用和负作用顺式元件以细胞特异性方式的复杂相互作用进行修饰。此外，观察到TGF-β刺激非SMC中几种早期而非晚期分化标志物的表达，表明单独的TGF-β不足以诱导非SMC转分化为SMC。
Transforming growth factor-beta (TCF-beta) has been shown to stimulate smooth muscle (SM) alpha-actin expression in smooth muscle cells (SMCs) and non-SMCs. We previously demonstrated that the 2 CArG boxes A and B and a novel TGF-beta control element (TCE) located within the first 125 bp of the SM alpha-actin promoter were required for TGF-beta inducibility of SM alpha-actin in SMCs. The aims of the present study were (1) to determine whether the TCE exhibits SMC specificity or contributes to TGF-beta induction of SM alpha-actin expression in non-SMCs (ie, endothelial cells and fibroblasts) and (2) to determine whether TGF-beta can induce expression of multiple TCE-containing SMC differentiation marker genes, such as SM22 alpha, h(1), calponin, and SM myosin heavy chain (SM MHC) in non-SMCs, Results of transient transfection assays demonstrated that mutation of CArG A, CArG B, or the TCE within a 125-bp promoter context completely abolished TGF-beta inducibility of SM alpha-actin in endothelial cells and fibroblasts. However, in contrast to observations in SMCs, inclusion of regions upstream from -155 completely repressed TGF-beta responsiveness in non-SMCs. Electrophoretic mobility shift assays showed that TGF-beta enhanced binding of a serum response factor to the CArG elements and the binding of an as-yet-unidentified factor to the TCE in endothelial cells and fibroblasts, but to a much lesser extent compared with SMCs, TGF-beta also stimulated expression of the SMC differentiation marker SM22 alpha in non-SMCs. However, in contrast to SMCs, TGF-beta did not induce expression of h(1), calponin and SM MHC in non-SMCs. In summary, these results suggest a conserved role for CArG A, CArG B, and the TCE in TGF-beta-induced expression of SM alpha-actin in SMCs and non-SMCs that is modified by a complex interplay of positive- and negative-acting cis elements in a cell-specific manner. Furthermore, observations that TGF-beta stimulated expression of several early but not late differentiation markers in non-SMCs indicate that TGF-beta alone is not sufficient to induce transdifferentiation of non-SMCs into SMCs.