Transforming Growth Factor-β1 (TGF-β1) Utilizes Distinct Pathways for the Transcriptional Activation of MicroRNA 143/145 in Human Coronary Artery Smooth Muscle Cells

Abstract

MicroRNA 143/145 (miR143/145) is restricted to adult smooth muscle cell (SMC) lineages and mediates, in part, the expression of several SMC contractile genes. Although the function of miR143/145 has begun to be elucidated, its transcriptional regulation in response to various signaling inputs is poorly understood. In an effort to define a miR signature for SMC differentiation, we screened human coronary artery SMCs for miRs modulated by TGF-␤1, a known stimulus for SMC differentiation. Array analysis revealed a number of TGF-␤1-induced miRs, including miR143/145. Validation studies showed that TGF-␤1 stimulated miR143/145 expression in a dose-and time-dependent manner. We utilized several chemical inhibitors and found that SB203580, a specific inhibitor of p38MAPK, significantly decreased TGF-␤1-induced miR143/145 expression. siRNA studies demonstrated that the effect of TGF-␤1 on miR143/145 was dependent upon the myocardin and serum response factor transcriptional switch as well as SMAD4. TGF-␤1 stimulated a 580-bp human miR143/145 enhancer, and mutagenesis studies revealed a critical role for both a known CArG box and an adjacent SMAD-binding element for full TGF-␤1-dependent activation of the enhancer. Chromatin immunoprecipitation assays documented TGF-␤1-mediated enrichment of SMAD3 and SMAD4 binding over the enhancer region containing the SMAD-binding element. Pre-miR145 strongly promoted SMC differentiation, whereas an antimiR145 partially blocked TGF-␤1-induced SMC differentiation. These results demonstrate a dual pathway for TGF-␤1-induced transcription of miR143/145, thus revealing a novel mechanism underlying TGF-␤1-induced human vascular SMC differentiation. SMCs3 display remarkable phenotypic adaptation in response to physical, chemical, and biological perturbations. Such altered SMC phenotypes play a major role in the pathogenesis of many human diseases, including asthma, atherosclerosis, restenosis, hypertension, transplant arteriopathy, and Alzheimer angiopathy (1-3). Accumulating evidence has shown SMC differentiation to be tightly regulated by an interacting network of environmental stimuli, signaling pathways, and various transcription factors, most notably SRF and MYOCD (2, 4 -8). TGF-␤1 is among the most potent soluble growth factors that activate SMC contractile gene expression in both specified SMC and non-SMC types (9 -15). Members of the TGF-␤1 superfamily transmit signals through both SMADdependent and SMAD-independent pathways (16). The classic pathway is through transmembrane serine-threonine kinase receptors, which mediate the phosphorylation of receptor-specific SMAD2 and SMAD3. The phosphorylated SMAD2-SMAD3 complex then interacts with the common SMAD4 to form a heteromeric complex, which translocates to the nucleus and binds to Smad-binding elements (SBE) located in the regulatory region of a number of target genes (16). SMAD-independent pathways, such as MAPK and PI3K, can also be triggered by TGF-␤ to initiate signal transduction and gene regulation (17,18). Both SMAD-dependent ...

An exclusive cellular and molecular network governs intestinal smooth muscle cell differentiation in vertebrates

“…miR-145 is one of the most enriched microRNAs in SMCs where it contributes to the acquisition of the SMC fate and contractile state (Albinsson and Swärd, 2013;Boettger et al, 2009;Cordes et al, 2009;Elia et al, 2009;Xin et al, 2009). Previous work has found that miR-145 expression is also regulated by TGFβ in vascular SMCs in vitro (Long and Miano, 2011). Therefore, we analyzed the expression of miR-145 in developing zebrafish embryos and observed that its expression begins at the onset of iSMC maturation (∼72 hpf ) (Fig.…”

MicroRNA-145 is a potential prognostic factor of scirrhous type gastric cancer

“…It has been shown that miR-143 and miR-145 have a number of common features (14)(15)(16). It is well known that their expression is mediated by the same promoter and is induced by TGF-β signaling (15), and they work cooperatively in the regulation of vascular smooth muscle cell differentiation (16). miR-145 was picked up as the second highest miRNA after miR-143 in our miRNA microarray analysis of scirrhous type GC (13).…”

“…Among them, we reported that miR-143 regulates collagen type III expression to contribute to interstitial fibrosis and the poor prognosis of scirrhous type GC (13). It has been shown that miR-143 and miR-145 have a number of common features (14)(15)(16). It is well known that their expression is mediated by the same promoter and is induced by TGF-β signaling (15), and they work cooperatively in the regulation of vascular smooth muscle cell differentiation (16).…”

Implication of MicroRNAs in the Pathophysiology of Cardiac and Vascular Smooth Muscle Cells

“…Interestingly, myocardin coactivator SRF regulates microRNA biogenesis, specifically the transcription of primicroRNA, thereby affecting the mature microRNA level, by binding to the proximal promoter region of miR genes. Transforming Growth Factor-1 (TGF 1), another known stimulus capable of inducing VSMC differentiation, has also been shown to induce both miR-143 and miR-145 in human coronary artery SMCs [59]. We have already discussed the importance of transcription factors SRF and MEF4 in the regulation of miR-1 and miR-133 (see subchapter 5).…”