Mechanism of atheroprotective function of Akt3 kinase

Akt3激酶的动脉粥样硬化保护功能机制

• 批准号: 8858363
• 负责人: EUGENE A PODREZ
• 金额: $ 39.63万
• 依托单位: CLEVELAND CLINIC LERNER COM-CWRU
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-03-09 至 2019-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8858363
• 关键词: AKT3 gene; Ablation; Apolipoprotein E; Apoptosis; Arteries; Atherosclerosis; Bone Marrow; Cardiovascular Diseases; Cardiovascular system; Cell physiology; Cells; Chimera organism; Cholesterol; Cholesterol Esters; Cholesterol Homeostasis; Coronary Arteriosclerosis; Disease; Esterification; Event; Family; Foam Cells; Genes; Genetic; Goals; Human; Human Cell Line; In Vitro; Lipids; Lipoproteins; Mammals; Marrow; Molecular; Mus; Pathway interactions; Patients; Phenotype; Phospholipids; Phosphorylation; Phosphotransferases; Physiology; Pinocytosis; Protein Isoforms; Protein Kinase; Protein-Serine-Threonine Kinases; Proteins; Regulation; Role; Signal Pathway; Specificity; Sterol O-Acyltransferase; Testing; atherogenesis; atheroprotective; cell growth; glucose metabolism; in vivo; knock-down; lipid metabolism; macrophage; monocyte; mutant; novel; novel strategies; novel therapeutic intervention; prevent; public health relevance; sterol O-acyltransferase 1; uptake

 DESCRIPTION (provided by applicant): Serine/threonine kinases Akt (also known as PKB), are among the most important and versatile protein kinases at the core of human physiology and disease. Akt regulate numerous cellular processes, including cell growth, glucose and lipid metabolism, differentiation, proliferation, and apoptosis. Three highly homologous Akt isoforms, encoded by three separate genes, are expressed in mammals. Combined deletions of the three Akt isoforms in the mouse suggest compensatory and complementary roles of isoforms. However, the three isoforms also have distinct functions, even though the mechanisms of specificity are only starting to emerge. Studies of the role of Akt, and specifically of Akt isofors, in atherogenesis are very limited. It has been recently shown that genetic ablation of Akt1 promotes coronary atherosclerosis via the enhanced expression of proinflammatory genes in the artery wall in a macrophage independent manner. We have recently explored the role of Akt3 in atherosclerosis using mice with a genetic ablation of the Akt3 gene. Our studies have demonstrated a specific, macrophage dependent, atheroprotective role for Akt3 in hyperlipidemic ApoE-/- mice. In a step-by-step fashion, we tested various potential mechanisms and demonstrated that the absence of Akt3 transforms macrophage into cell which aggressively accumulates cholesterol esters via two mechanisms: increased lipoprotein uptake via pinocytosis, and parallel increased protein stability of cholesterol esterifying enzyme ACAT1 (also known as SOAT1). Multiple lines of evidence suggested that Akt3 suppresses atherosclerosis by restricting cholesteryl ester accumulation and foam cell formation in macrophages, an early and critical step in atherogenesis. The mechanism is Akt isoform specific, and our preliminary studies suggest that one mechanism for specificity is via differentia subcellular localization of Akt1 (a major isoform in macrophages) and Akt3 in macrophages. The long-term goal of this proposal is to investigate the molecular mechanism of Akt3 regulation of macrophage function. As a specific hypothesis, we propose that Akt3 specifically suppresses transformation of macrophage into lipid accumulating phenotype by inhibiting macrophage pinocytosis and by regulating a particular branch of cholesterol metabolism - cholesterol esterification via direct regulation of ACAT1 protein stability. We will investigate the role of AK3 in atherogenesis in vivo and in vitro with a particular focus on the molecular mechanisms of regulation of Akt3 activity, ACAT1 expression and pinocytosis.

 描述（由适用提供）：丝氨酸/苏氨酸激酶AKT（也称为PKB），是人类生理和疾病核心最重要，最重要的蛋白激酶之一。 AKT调节许多细胞过程，包括细胞生长，葡萄糖和脂质代谢，分化，增殖和凋亡。哺乳动物中表达了三个高度同源的Akt同工型，由三个单独的基因编码。小鼠中三个AKT同工型的结合缺失表明同工型的补偿性和互补作用。但是，即使特异性机制刚刚开始出现，这三种同工型也具有不同的功能。研究AKT的作用，特别是Akt同层，在动脉粥样硬化中的研究非常有限。最近已经显示，Akt1的遗传消融通过以巨噬细胞独立的方式通过增强动脉壁中促炎基因的表达来促进冠状动脉粥样硬化。我们最近使用具有Akt3基因的遗传消融的小鼠探索了Akt3在动脉粥样硬化中的作用。我们的研究表明，Akt3在高脂型APOE - / - 小鼠中具有特定的巨噬细胞依赖性，动脉瘤作用。我们以逐步的方式测试了各种潜在的机制，并证明缺乏AKT3将巨噬细胞转化为细胞，通过两种机制积极积累胆固醇酯：通过生皮的脂蛋白摄取量增加，并行增加了胆固醇酯酯酯的蛋白质稳定性，也称为eNzyme acat11（也已知）。多种证据表明，AKT3通过限制巨噬细胞中胆固醇酯的积累和泡沫细胞形成来抑制动脉粥样硬化，这是动脉粥样硬化的早期和关键步骤。该机制是Akt同工型特异性的，我们的初步研究表明，特异性的一种机制是通过Akt1（巨噬细胞中的主要同工型）和巨噬细胞中AKT3的差异化机制。该提案的长期目标是研究巨噬细胞功能的AKT3调节的分子机制。作为一个特定的假设，我们提出，AKT3通过抑制巨噬细胞性生物细胞增多症和控制胆固醇代谢的特定分支 - 胆固醇代谢 - 通过直接调节ACAT1蛋白质稳定性来抑制巨噬细胞积累表型的转化。我们将研究AK3在体内和体外的动脉粥样硬化中的作用，特别侧重于AKT3活性，ACAT1表达和性腺胞毒性调节的分子机制。