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: 8813881
• 负责人: Leila Gobejishvili
• 金额: $ 18.47万
• 依托单位: UNIVERSITY OF LOUISVILLE
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-10 至 2021-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8813881
• 关键词: Address; Attenuated; Cells; 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; Hepatic Stellate Cell; Hepatocyte; In Vitro; Inflammation; Injury; Knockout Mice; Liver Fibrosis; Mass Spectrum Analysis; Mediating; Modeling; Modification; Myofibroblast; PDE4B; 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; Request for Proposals; 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; second messenger; 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细胞激活的伤口愈合过程 （HSC）。但是，持续的肝细胞损伤和感染导致不受控制的激活和 HSC的增殖和肝纤维化的发展，导致肝硬化甚至肝细胞癌。 尽管取得了进步，但差距仍在我们对涉及的机制的理解中 HSC从静止表型转变。最近，我们发现 酶的磷酸二酯酶4（PDE4）酶亚科在胆固醇的发展中起致病作用 肝损伤和纤维化。值得注意的是，静态HSC中不存在PDE4，并在 体外激活。此外，PDE4特异性抑制剂rolipram有效地减弱了SMA，胶原蛋白 HSC中的表达和参与形态变化。 PDE4是营地中最大的亚家族。 水解PDE，严格调节细胞cAMP的水平。营地，通过其效应分子 蛋白激酶A（PKA）和交换蛋白质直接被CAMP（EPAC）激活，已被证明是向下降低的 调节细胞因子诱导的非羊皮细胞中的纤维纤维基因。因此，我们假设PDE4的诱导 表达和活动在HSC激活中起因果作用，通过减少CAMP-PKA/EPAC活性和 促进纤维化信号传导。我们假设在HSC激活期间，启动子相关的表观遗传学 变化和翻译后修饰在调节PDE4表达和 活动。我们还假设PDE4抑制作用将恢复PKA/EPAC活动并衰减TGF¿-SMAD 通过：（i）相关MAPK的灭活； （ii）取消抑制PPAR€导致改进 SMA和COL1A1的表达。重要的是，抑制PDE4活性可能是一种显着的治疗性 肝纤维化的方法。该提议的具体目的是：1）确定PDE4在 调节HSC中的纤维化信号传导； 2）确定与启动子相关的表观遗传修饰 在HSC激活过程中有助于PDE4同工型的诱导； 3）确定翻译后 在HSC激活过程中，与PDE4同工型功能相关的修改（PTM）。重要的是，结果 由山脉资助的项目将为体内翻译研究提供原理和机械原理证明 （R01）检查PDE4针对预防和治疗肝纤维化的策略。