Pathogenic role of PDE4 in hepatic stellate cell activation and TGF signaling

PDE4 在肝星状细胞活化和 TGF 信号传导中的致病作用

• 批准号: 9293341
• 负责人: Leila Gobejishvili
• 金额: $ 18.86万
• 依托单位: UNIVERSITY OF LOUISVILLE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/9293341
• 关键词: Address; Attenuated; Centers of Research Excellence; Cirrhosis; Collagen; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; DNA Modification Process; Development; Enzymes; Epigenetic Process; Etiology; FDA approved; Family; Fibrosis; Funding; Genes; Genetic Transcription; Hepatic Stellate Cell; Hepatocyte; In Vitro; Inflammation; Injury; Knockout Mice; Liver Fibrosis; Mass Spectrum Analysis; Mediating; Modeling; Modification; Morphology; Myofibroblast; PDE4B; Pathogenicity; Peroxisome Proliferator-Activated Receptors; Phenotype; Phosphorylation; Play; Post-Translational Protein Processing; Prevention strategy; Primary carcinoma of the liver cells; Process; Promoter Regions; Protein Isoforms; Proteins; Proteomics; Rattus; Regulation; Role; Rolipram; Second Messenger Systems; Signal Transduction; Therapeutic; Toxicology; Transcriptional Activation; Wound Healing; base; cell transformation; cytokine; experimental analysis; histone modification; in vivo; inhibitor/antagonist; liver injury; member; phosphodiesterase IV; promoter; translational study

Liver injury of different etiologies leads to a wound healing process involving activation of hepatic stellate cells (HSCs). However, an ongoing hepatocyte injury and inflammation results in an uncontrolled activation and proliferation of HSCs and development of hepatic fibrosis leading to cirrhosis and even hepatocellular cancer. Despite the advances made, gaps remain in our understanding of the mechanisms involved in the process of HSC transformation from quiescent to activated phenotype. Recently, we discovered that the phosphodiesterase 4 (PDE4) subfamily of enzymes play a pathogenic role in the development of cholestatic liver injury and fibrosis. Notably, PDE4s are not present in quiescent HSCs and are rapidly induced upon activation in vitro. Further, the PDE4 specific inhibitor, rolipram, effectively attenuates ¿SMA, collagen expression and accompanying morphological changes in HSCs. PDE4 is the largest sub-family among cAMP- hydrolyzing PDEs, which tightly regulate the levels of cellular cAMP. cAMP, through its effector molecules protein kinase A (PKA) and Exchange Protein directly Activated by cAMP (EPAC), has been shown to down- regulate cytokine induced fibrogenic genes in non-hepatic cells. Hence, we hypothesize that induction of PDE4 expression and activity plays a causal role in HSC activation by decreasing cAMP-PKA/EPAC activities and promoting fibrogenic signaling. We postulate that during HSC activation, promoter associated epigenetic changes and post-translational modifications play a significant role in the regulation of PDE4 expression and activity. We also postulate that PDE4 inhibition will restore PKA/EPAC activities and attenuate TGF¿-Smad signaling through: (i) inactivation of relevant MAPKs; and (ii) de-repressing PPAR¿ leading to decreased expression of ¿SMA and Col1A1. Importantly, inhibition of PDE4 activity may be a significant therapeutic approach for liver fibrosis. The specific aims of this proposal are to: 1) Determine the role of PDE4 in the regulation of fibrogenic signaling in HSCs; 2) Determine promoter-associated epigenetic modifications contributing to the induction of PDE4 isoforms during HSC activation; and 3) Determine the post-translational modifications (PTMs) relevant for PDE4 isoform function during HSC activation. Importantly, the results of this COBRE-funded project will provide proof-of-principle and mechanistic rationale for in vivo translational studies (R01) to examine PDE4 targeted strategies for prevention and treatment of hepatic fibrosis.

不同病因的肝损伤导致涉及肝星状细胞激活的伤口愈合过程 （HSC）。然而，持续的肝细胞损伤和炎症会导致不受控制的激活和 造血干细胞增殖和肝纤维化发展导致肝硬化甚至肝细胞癌。 尽管取得了进展，但我们对这一过程所涉及机制的理解仍然存在差距。 HSC 从静止表型向激活表型的转变。最近，我们发现， 磷酸二酯酶 4 (PDE4) 酶亚家族在胆汁淤积的发展中发挥致病作用 肝损伤和纤维化。值得注意的是，PDE4 不存在于静止的 HSC 中，并且在静止状态下迅速被诱导。 体外激活。此外，PDE4 特异性抑制剂咯利普兰可有效减弱 ¿SMA、胶原蛋白 HSC 中的表达和伴随的形态变化。 PDE4是cAMP中最大的亚家族 水解 PDE，严格调节细胞 cAMP 水平。 cAMP，通过其效应分子 蛋白激酶 A (PKA) 和由 cAMP 直接激活的交换蛋白 (EPAC) 已被证明可以降低 调节非肝细胞中细胞因子诱导的纤维化基因。因此，我们假设 PDE4 的诱导 表达和活性通过降低 cAMP-PKA/EPAC 活性而在 HSC 激活中发挥因果作用 促进纤维化信号传导。我们假设在 HSC 激活过程中，启动子相关的表观遗传 变化和翻译后修饰在 PDE4 表达的调节中起着重要作用 活动。我们还假设 PDE4 抑制将恢复 PKA/EPAC 活性并减弱 TGF¿-Smad 通过以下方式发出信号： (i) 相关 MAPK 失活； (ii) 去抑制 PPAR¿ 导致减少 ¿SMA 和 Col1A1 的表达。重要的是，抑制 PDE4 活性可能是一种重要的治疗方法。 治疗肝纤维化的方法。该提案的具体目标是： 1) 确定 PDE4 在 HSC 中纤维发生信号的调节； 2) 确定启动子相关的表观遗传修饰 在 HSC 激活过程中有助于诱导 PDE4 同工型； 3) 确定翻译后 HSC 激活期间与 PDE4 同工型功能相关的修饰 (PTM)。重要的是，这次的结果 COBRE 资助的项目将为体内转化研究提供原理验证和机制原理 (R01) 检查 PDE4 预防和治疗肝纤维化的靶向策略。