Inhibition of cardiac myofibroblast formation and collagen synthesis by activation and overexpression of adenylyl cyclase
Inhibition of cardiac myofibroblast formation and collagen synthesis by activation and overexpression of adenylyl cyclase
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DOI：
10.1073/pnas.0408704102
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发表时间：
2005-01-11
影响因子：
11.1
通讯作者：
Insel, PA
中科院分区：
文献类型：
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作者：
Swaney, JS;Roth, DM;Insel, PA
成纤维细胞向肌成纤维细胞的转化是结缔组织重塑中的关键事件，其特征在于α-平滑肌肌动蛋白（α-SMA）的表达和细胞外基质（ECM）组分的产生。在诸如心脏的组织中需要抑制这种转化的方法，其中心脏成纤维细胞（CF）过度产生ECM导致纤维化、心肌硬化和心脏功能障碍。我们测试了腺苷酸环化酶（AC）激活（cAMP水平增加）是否调节成年大鼠CF向肌成纤维细胞的转化，通过免疫荧光显微镜、免疫印迹和胶原合成进行评估。CF与TGF-β或血管紧张素II孵育24小时可增加α-SMA表达，而AC激动剂毛喉素和激活蛋白激酶A的cAMP类似物可抑制α-SMA表达。治疗与毛喉素钝化血清，TGF-β，和血管紧张素II刺激胶原蛋白的合成。过表达6型AC的CF增强了毛喉素促进的cAMP形成，毛喉素对TGF-β刺激的α-SMA表达的抑制作用更大，毛喉素减少血清刺激的胶原合成的EC 50降低。AC刺激激动剂肾上腺髓质素抑制胶原合成的CF过表达AC 6，但在控制。因此，AC刺激钝化胶原蛋白合成，并且平行地钝化成年大鼠CF向肌成纤维细胞的转化。AC过表达增强了这些作用，“揭示”了肾上腺髓质素的抑制作用。这些发现暗示cAMP通过阻断CF向肌成纤维细胞的转化而作为ECM形成的抑制剂，并且表明增加AC表达，从而通过刺激CF上表达的受体来增强cAMP产生，可以提供减弱和预防心脏纤维化及其后遗症的手段。
Transformation of fibroblasts to myofibroblasts, characterized by expression of alpha-smooth muscle actin (alpha-SMA) and production of extracellular matrix (ECM) components, is a key event in connective tissue remodeling. Approaches to inhibit this transformation are needed in tissues, such as the heart, where excessive ECM production by cardiac fibroblasts (CFs) causes fibrosis, myocardial stiffening, and cardiac dysfunction. We tested whether adenylyl cyclase (AC) activation (increased cAMP levels) modulates the transformation of adult rat CF to myofibroblasts, as assessed by immunofluorescent microscopy, immunoblotting, and collagen synthesis. A 24-h incubation of CF with TGF-beta or angiotensin II increased alpha-SMA expression, which was inhibited by the AC agonist forskolin and a cAMP analog that activates protein kinase A. Treatment with forskolin blunted serum-, TGF-beta-, and angiotensin II-stimulated collagen synthesis. CFs engineered to overexpress type 6 AC had enhanced forskolin-promoted cAMP formation, greater inhibition by forskolin of TGF-beta-stimulated alpha-SMA expression, and a decrease in the EC50 of forskolin to reduce serum-stimulated collagen synthesis. The AC stimulatory agonist adrenomedullin inhibited collagen synthesis in CF that overexpressed AC6 but not in controls. Thus, AC stimulation blunts collagen synthesis and, in parallel, the transformation of adult rat CF to myofibroblasts. AC overexpression enhances these effects, "uncovering" an inhibition by adrenomedullin. These findings implicate cAMP as an inhibitor of ECM formation by means of blockade of the transformation of CF to myofibroblasts and suggest that increasing AC expression, thereby enhancing cAMP generation through stimulation of receptors expressed on CF, could provide a means to attenuate and prevent cardiac fibrosis and its sequelae.