Molecular Mechanism of Protein Kinase Cbeta-Mediated Cholesterol Homeostasis

蛋白激酶Cbeta介导的胆固醇稳态的分子机制

• 批准号: 7653553
• 负责人: KAMAL D MEHTA
• 金额: $ 37.5万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-12-06 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7653553
• 关键词: 1,2-diacylglycerol; Abbreviations; Accounting; Adipocytes; Adipose tissue; Affect; Age; Aging; Anabolism; Animals; Antiatherogenic; Apolipoprotein E; Apolipoproteins B; Arterial Fatty Streak; Arts; Atherosclerosis; Binding; Binding Proteins; Blood Circulation; Blood Vessels; Brown Fat; Buffers; Cardiovascular Diseases; Cause of Death; Cell Nucleus; Central obesity; Cessation of life; Cholesterol; Cholesterol Homeostasis; Complex; Coronary Arteriosclerosis; Cultured Cells; Cytosol; DNA-Protein Interaction; Death Rate; Developed Countries; Development; Diabetes Mellitus; Diagnosis; Diet; Diet Habits; Dietary Cholesterol; Diglycerides; Disease; Dyslipidemias; Endocrine; Epidemic; Etiology; Evaluation; Event; Fatty acid glycerol esters; Functional disorder; Gene Expression; Genes; Genetic; Genetic Transcription; Goals; Golgi Apparatus; Heart Diseases; Helix-Turn-Helix Motifs; Hepatic; Hepatocyte; Histone H3; Homeostasis; Human; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hyperglycemia; Hypertriglyceridemia; Inflammation; Insulin Receptor; Insulin Resistance; Interleukin-6; Investigation; Knock-out; Knockout Mice; Knowledge; LDL Cholesterol Lipoproteins; Link; Lipids; Liver; Low Density Lipoprotein Receptor; Low-Density Lipoproteins; MAPK7 gene; Mediating; Membrane; Metabolic; Modification; Molecular; Molecular Biology; Mus; Mutant Strains Mice; Nuclear; Obesity; Pathogenesis; Patients; Phenotype; Phosphorylation; Phosphotransferases; Physiological; Physiology; Plasma; Play; Population; Prevention; Preventive; Process; Protein Binding; Protein Isoforms; Protein Kinase; Protein Kinase C; Proto-Oncogene Proteins c-akt; Regulation; Response Elements; Risk Factors; Role; Serine; Signal Pathway; Signal Transduction; Smoke; Smoking; Sterols; Stress; Stroke; Techniques; Time; Tissues; Transgenic Mice; Transgenic Organisms; Triglycerides; Tumor Necrosis Factor-alpha; Tumor Necrosis Factors; United States; Up-Regulation; Vascular Cell Adhesion Molecule-1; Very low density lipoprotein; Weather; Work; adipokines; atherogenesis; base; citrate carrier; diabetic; disorder prevention; fatty acid-binding proteins; feeding; gain of function; human NOS3 protein; hypercholesterolemia; in vivo; inhibitor/antagonist; lifestyle factors; link protein; lipid disorder; loss of function; mouse model; non-diabetic; overexpression; prevent; promoter; protein complex; protein kinase C beta; public health relevance; receptor expression; response; ruboxistaurin; transcription factor; trend; uptake

DESCRIPTION (provided by applicant): Every year in the United States nearly 1 million deaths occur among the 7 million people affected with cardiovascular diseases. The dominant underlying factor for this disease includes elevated plasma low density lipoprotein (LDL)-cholesterol levels in association with hypertriglyceridemia, abdominal obesity, or insulin resistance. The plasma levels of LDL are strongly influenced by dietary cholesterol and body's ability to store and metabolize ingested cholesterol. Considering that adipose tissue accumulates one of the largest pools of exchangeable free cholesterol, there is no information available regarding the role and regulation of adipose LDL receptors and its relationship to whole body cholesterol homeostasis. Also, our knowledge of the signaling pathway controlling adipose endocrine and lipo-metabolic functions through sterol-response element binding protein-1c (SREBP-1c) is limited, as is the role of this kinase in diet-induced atherosclerosis. We previously showed, for the first time, involvement of specific isoforms of protein kinase C (PKC) in regulating hepatic LDL receptor expression. In order to extend these studies to whole animal, we have been studying consequences of PKCbeta deficiency on lipid homeostasis. Based on our most recent observations linking PKCbeta deficiency to reduced plasma LDL levels, increased adipose nuclear SREBP-1c resulting in LDL receptor induction, and changes in plasma adipokines levels, we propose that PKCbeta plays a critical role in cholesterol homeostasis by regulating adipose SREBP-1c processing, thus regulating genes of lipid homeostasis and atherosclerosis. In Specific Aim 1, role of PKCbeta in LDL homeostasis will be established by evaluating effects of PKCbeta deficiency on hepatic biosynthesis and clearance, as well as adipose uptake of plasma LDL. To understand the molecular basis, we will also determine PKCbeta-dependent changes in the adipose gene expression and whether overexpression of adipose PKCbeta rescues the phenotype or adipose-specific PKCbeta deficiency alone can account for this phenotype. Specific Aim beta will define the nuclear and cytoplasmic events at the molecular level by which PKCbeta deficiency promotes nuclear accumulation of SREBP-1c and induction of adipose LDL receptors, without affecting hepatic LDL receptor expression. Finally, Specific Aim 3 will investigate the role of PKCbeta in cholesterol-rich-diet-induced atherosclerosis in PKCbeta-/- x ApoE-/- mice under diabetic or nondiabetic conditions. We already have these mice and initial results are very encouraging and have the potential to provide the molecular basis of diabetes-induced atherosclerosis and an alternative to statin. The proposed studies will not only establish the role of PKCbeta in regulating whole body cholesterol homeostasis, but will also identify genes regulated by this kinase, to correlate regulatory mechanisms to animal physiology. Accomplishment of the above aims will unravel a central signaling component that may control dyslipidemia and atherosclerosis by regulating adipose tissue physiology; modulation of its activity may be the preferable mode for the treatment of lipid disorders and prevention of atherosclerosis in the beta1st century. PUBLIC HEALTH RELEVANCE: Cardiovascular disease remains the leading cause of death in industrialized nations despite major advances in its diagnosis, treatment, and prevention. The underlying aetiology is not clarified, but includes a strong genetic component as well as lifestyle factors such as physical inactivity, dietary habits and smoking. While there has been a trend over the last half century showing a general decline in the age-adjusted death rates of heart disease and stroke, the increasing epidemics of obesity, followed closely by insulin resistance and diabetes, will likely slow the decline and reverse this trend. It is both necessary and timely to define roles of protein kinase Cbeta isoform that simultaneously modify all risk factors. The greatest potential for arresting this epidemic is likely to come through a clearer understanding of its molecular pathogenesis to develop rational and mechanism based therapy.

描述(申请人提供)：在美国，每年有700万心血管疾病患者中有近100万人死亡。这种疾病的主要潜在因素包括血浆低密度脂蛋白(LDL)-胆固醇水平升高，与高甘油三酯血症、腹型肥胖或胰岛素抵抗有关。低密度脂蛋白的血浆水平受到饮食胆固醇和身体储存和代谢摄入胆固醇的能力的强烈影响。考虑到脂肪组织积累了最大的可交换游离胆固醇池之一，目前还没有关于脂肪低密度脂蛋白受体的作用和调节及其与全身胆固醇稳态的关系的信息。此外，我们对通过类固醇反应元件结合蛋白-1c(SREBP-1c)控制脂肪内分泌和脂代谢功能的信号通路的了解也很有限，就像该激酶在饮食诱导的动脉粥样硬化中所起的作用一样。我们先前首次发现蛋白激酶C(PKC)的特定亚型参与调节肝脏低密度脂蛋白受体的表达。为了将这些研究扩展到整个动物，我们一直在研究PKCβ缺乏对脂质稳态的影响。根据我们最近的观察，PKCβ缺乏与血浆低密度脂蛋白水平降低、导致低密度脂蛋白受体诱导的脂肪核SREBP-1c增加以及血浆脂肪因子水平的变化有关，我们认为PKCβ通过调节脂肪SREBP-1c的加工，从而调节脂质稳态和动脉粥样硬化的基因，在胆固醇稳态中发挥关键作用。在具体目标1中，将通过评估PKCβ缺乏对肝脏生物合成和清除以及对血浆低密度脂蛋白的脂肪吸收的影响来确定PKCβ在低密度脂蛋白动态平衡中的作用。为了了解其分子基础，我们还将确定脂肪基因表达的PKCβ依赖的变化，以及脂肪PKCβ的过度表达是否拯救了表型，或者脂肪特异性PKCβ缺乏本身就可以解释这种表型。在分子水平上，PKCβ缺乏可促进SREBP-1c的核积聚和脂肪低密度脂蛋白受体的诱导，而不影响肝脏低密度脂蛋白受体的表达。最后，特殊目标3将研究PKCβ在糖尿病或非糖尿病条件下高胆固醇饮食诱导的PKCβ/-x ApoE-/-小鼠动脉粥样硬化中的作用。我们已经有了这些小鼠，初步结果非常令人鼓舞，有可能为糖尿病引起的动脉粥样硬化提供分子基础，并提供他汀类药物的替代品。这项拟议的研究不仅将确定PKCβ在调节全身胆固醇稳态中的作用，而且还将确定由该激酶调节的基因，以将调节机制与动物生理联系起来。上述目标的实现将揭开一个可能通过调节脂肪组织生理来控制血脂异常和动脉粥样硬化的中枢信号成分；调节其活性可能是1世纪治疗血脂紊乱和预防动脉粥样硬化的首选模式。公共卫生相关性：尽管心血管疾病在诊断、治疗和预防方面取得了重大进展，但它仍然是工业化国家的主要死亡原因。潜在的病因尚未阐明，但包括强大的遗传成分以及生活方式因素，如缺乏体育锻炼、饮食习惯和吸烟。尽管过去半个世纪有一种趋势显示，经年龄调整的心脏病和中风死亡率普遍下降，但肥胖的日益流行，以及紧随其后的胰岛素抵抗和糖尿病，可能会减缓这一下降趋势，并扭转这一趋势。确定蛋白激酶Cβ亚型同时改变所有危险因素的作用既有必要也是及时的。遏制这种流行病的最大潜力可能来自于更清楚地了解其分子发病机制，以开发合理的、基于机制的治疗方法。