High glucose induces Smad activation via the transcriptional coregulator p300 and contributes to cardiac fibrosis and hypertrophy
High glucose induces Smad activation via the transcriptional coregulator p300 and contributes to cardiac fibrosis and hypertrophy
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DOI：
10.1186/1475-2840-13-89
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发表时间：
2014-05-05
影响因子：
9.3
通讯作者：
Connelly, Kim A.
中科院分区：
文献类型：
--
作者：
Bugyei-Twum, Antoinette;Advani, Andrew;Connelly, Kim A.
背景：尽管心力衰竭的治疗取得了进展，但死亡率仍然很高，特别是在糖尿病患者中。活化的转化生长因子β（TGF-β）有助于糖尿病心肌病中观察到的纤维化结节的发病机制。我们假设高葡萄糖增强了转录共激活因子p300的活性，通过Smad 2的乙酰化激活TGF-β;并且通过抑制p300，TGF-β活性将降低，并在临床相关的糖尿病心肌病动物模型中预防心力衰竭。方法：在正常葡萄糖（5.6mmol/L-NG）和高糖（25 mmol/L-HG）条件下，在H9 c2心肌细胞中评估p300活性。心脏成纤维细胞中的H-3-脯氨酸掺入也被评估为胶原合成的标志物。用已知的p300抑制剂姜黄素或p300 siRNA在体外研究了p300活性在修饰TGF-β活性中的作用，并在血液动力学验证的糖尿病心肌病模型-糖尿病TG m（Ren-2）27大鼠中使用姜黄素评估了p300抑制的功能效应。在体外，暴露于HG的H9 c2细胞表现出增加的p300活性、Smad 2乙酰化和增加的TGF-β活性，如通过Smad 7诱导所评估的（所有p < 0.05 c/w NG）。此外，HG诱导H-3-脯氨酸掺入作为胶原合成的标志物（p < 0.05 c/w NG）。使用siRNA或姜黄素的p300抑制降低了p300活性、Smad乙酰化和TGF-β活性（所有p < 0.05 c/w载体或乱序siRNA）。此外，姜黄素治疗减少HG和TGF-β刺激的成纤维细胞中的H-3-脯氨酸掺入（p < 0.05 c/w NG）。为了确定p300抑制的功能意义，将糖尿病Ren-2大鼠随机接受姜黄素或载体6周。姜黄素治疗减少了心脏肥大，改善了舒张功能，减少了细胞外基质的产生，而不影响血糖控制，沿着TGF-β活性的降低，如通过Smad 7活化评估的（所有p < 0.05 c/w载体治疗的糖尿病动物）。这些发现表明高葡萄糖增加了转录辅调节因子p300的活性，其通过Smad 2乙酰化增加TGF-β活性。调节p300可能是治疗糖尿病心力衰竭的一种新策略。
Background: Despite advances in the treatment of heart failure, mortality remains high, particularly in individuals with diabetes. Activated transforming growth factor beta (TGF-beta) contributes to the pathogenesis of the fibrotic interstitium observed in diabetic cardiomyopathy. We hypothesized that high glucose enhances the activity of the transcriptional co-activator p300, leading to the activation of TGF-beta via acetylation of Smad2; and that by inhibiting p300, TGF-beta activity will be reduced and heart failure prevented in a clinically relevant animal model of diabetic cardiomyopathy.Methods: p300 activity was assessed in H9c2 cardiomyoblasts under normal glucose (5.6 mmol/L-NG) and high glucose (25 mmol/L-HG) conditions. H-3-proline incorporation in cardiac fibroblasts was also assessed as a marker of collagen synthesis. The role of p300 activity in modifying TGF-beta activity was investigated with a known p300 inhibitor, curcumin or p300 siRNA in vitro, and the functional effects of p300 inhibition were assessed using curcumin in a hemodynamically validated model of diabetic cardiomyopathy - the diabetic TG m(Ren-2)27 rat.Results: In vitro, H9c2 cells exposed to HG demonstrated increased p300 activity, Smad2 acetylation and increased TGF-beta activity as assessed by Smad7 induction (all p < 0.05 c/w NG). Furthermore, HG induced H-3-proline incorporation as a marker of collagen synthesis (p < 0.05 c/w NG). p300 inhibition, using either siRNA or curcumin reduced p300 activity, Smad acetylation and TGF-beta activity (all p < 0.05 c/w vehicle or scrambled siRNA). Furthermore, curcumin therapy reduced H-3-proline incorporation in HG and TGF-beta stimulated fibroblasts (p < 0.05 c/w NG). To determine the functional significance of p300 inhibition, diabetic Ren-2 rats were randomized to receive curcumin or vehicle for 6 weeks. Curcumin treatment reduced cardiac hypertrophy, improved diastolic function and reduced extracellular matrix production, without affecting glycemic control, along with a reduction in TGF-beta activity as assessed by Smad7 activation (all p < 0.05 c/w vehicle treated diabetic animals).Conclusions: These findings suggest that high glucose increases the activity of the transcriptional co-regulator p300, which increases TGF-beta activity via Smad2 acetylation. Modulation of p300 may be a novel strategy to treat diabetes induced heart failure.