Apoptosis pathways underlying adipogenesis

脂肪生成的细胞凋亡途径

• 批准号: 8413404
• 负责人: Niketa A. Patel
• 金额: --
• 依托单位: JAMES A. HALEY VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8413404
• 关键词: Accounting; Adipocytes; Adipose tissue; Adult; Affect; Alternative Splicing; Apoptosis; Apoptotic; Behavioral; Cardiovascular Diseases; Cause of Death; Cell Survival; Complement; Curcumin; Data; Development; Diet; Disease; Epidemic; Event; Exhibits; Expenditure; Fatty acid glycerol esters; Future; Gene Expression; General Population; Genes; Genetic; Genomics; Goals; Health; Health Care Costs; Healthcare; High Prevalence; Intervention; Knowledge; Link; Measures; Mediating; Mediator of activation protein; Medical; Mesenchymal; Metabolic syndrome; Molecular; Morbidity - disease rate; Non-Insulin-Dependent Diabetes Mellitus; Obese Mice; Obesity; Outcome; Overweight; Pathway interactions; Phenotype; Phosphotransferases; Physiological; Population; Prevalence; Prevalence Study; Preventive; Protein-Serine-Threonine Kinases; Public Health; RNA Splicing; Research; Resveratrol; Risk Factors; Role; Services; Signal Transduction; Socioeconomic Factors; Spliced Genes; Therapeutic; Therapeutic Intervention; Tissues; Transcriptional Regulation; Variant; Veterans; Weight; Weight Gain; adipocyte differentiation; base; cancer type; caspase-9; combat; design; feeding; inhibitor/antagonist; innovation; lipid biosynthesis; mouse model; obesity treatment; overexpression; precursor cell; prevent; programs; research study; therapeutic evaluation; upstream kinase

DESCRIPTION (provided by applicant): Obesity continues to escalate as a significant public health problem and as the leading preventable cause of death. Genetic, environmental, behavioral, and socioeconomic factors cause excess weight gain and obesity. Increased proliferation and differentiation of pre-adipocytes to mature adipocytes (adipogenesis) within the fat tissues are central to obesity. Previous studies focused extensively on the transcriptional controls which maintain the adipocyte phenotype. However, the underlying molecular mechanisms that promote determination of primitive mesenchymal precursor cells to the adipose phenotype are still unknown. Our long-term goal is to elucidate the cellular and molecular mechanisms underlying adipogenesis. In pursuit of this goal, our objective is to determine how alternative splicing of apoptotic genes govern the differentiation and maturation of pre-adipocytes. It is well documented that pre-adipocytes undergo apoptosis while mature adipocytes fail to do so. Based on preliminary data, our central hypothesis is that there is a distinct shift in the expression of genes involved in apoptosis from a pro-apoptotic to a pro-survival pathway via alternative splicing controlling terminal adipocyte differentiation which ultimately increases the adipose number and mass leading to obesity. The significance of the proposed research is that once we establish the molecular mechanisms of adipogenesis which result in increased survival of adipocytes, we can manipulate targets of the apoptosis pathway to devise new and innovative approaches to prevent or reverse weight gain and obesity. We propose three specific aims. In Aim 1, we will elucidate whether terminal adipocyte differentiation is accompanied by alternative expression of apoptosis genes. Pre-adipocytes undergo apoptosis unlike mature adipocytes. Our data demonstrate that during adipocyte differentiation between days 4-6, expression of Bcl2 and Bcl-x, caspase 9 and PKC4 alternatively spliced variants change to its pro-survival variants. Using overexpression and knockdown experiments, we will elucidate the link between these genes, adipogenesis and apoptosis. Aim 2 is designed to determine the role of the signaling kinase PKC4II as an anti-adipogenic mediator. PKC4II, a serine/threonine protein kinase promotes cell survival. Natural compounds such as resveratrol and curcumin exhibit anti-adipogenic activities and promote apoptosis in adipocytes. Our data shows that they inhibit PKC4II expression. Our data further points to PKC4II as the signaling kinase upstream of Bcl2-mediated survival pathway. We propose to identify the intracellular target which is central to pro-survival pathways in adipocytes that may be modulated to induce anti-adipogenic effects. In Aim 3 the physiological relevance of this hypothesis will be assessed determining the expression levels of these apoptosis genes in diet-induced obese mouse model (C57BL/6) fed a high-fat diet complemented with the natural compounds or a PKC4II-specific inhibitor. By showing that alternative splicing of apoptotic genes modulate differentiation and maturation of pre-adipocytes, the proposed studies will establish a new paradigm for adipogenesis and reveal new targets for treatment of obesity.

描述（由申请人提供）： 肥胖作为一个重大的公共卫生问题和可预防的主要死因继续升级。遗传、环境、行为和社会经济因素导致体重过度增加和肥胖。脂肪组织内前脂肪细胞增殖和分化为成熟脂肪细胞（脂肪生成）的增加是肥胖的核心。先前的研究广泛关注维持脂肪细胞表型的转录控制。然而，促进原始间充质前体细胞确定脂肪表型的潜在分子机制仍然未知。我们的长期目标是阐明脂肪生成的细胞和分子机制。为了实现这一目标，我们的目标是确定凋亡基因的选择性剪接如何控制前脂肪细胞的分化和成熟。有充分证据表明，前脂肪细胞会发生凋亡，而成熟脂肪细胞则不会发生凋亡。基于初步数据，我们的中心假设是，参与细胞凋亡的基因表达通过控制末端脂肪细胞分化的选择性剪接从促细胞凋亡途径转变为促生存途径，最终增加脂肪数量和质量，导致肥胖。这项研究的意义在于，一旦我们建立了导致脂肪细胞存活率增加的脂肪生成的分子机制，我们就可以操纵细胞凋亡途径的靶点，设计出新的创新方法来预防或逆转体重增加和肥胖。 我们提出三个具体目标。在目标 1 中，我们将阐明终末脂肪细胞分化是否伴随着凋亡基因的替代表达。与成熟脂肪细胞不同，前脂肪细胞经历细胞凋亡。我们的数据表明，在第 4-6 天的脂肪细胞分化过程中，Bcl2 和 Bcl-x、caspase 9 和 PKC4 选择性剪接变体的表达变为其促存活变体。通过过度表达和敲低实验，我们将阐明这些基因、脂肪生成和细胞凋亡之间的联系。目标 2 旨在确定信号激酶 PKC4II 作为抗脂肪生成介质的作用。 PKC4II 是一种丝氨酸/苏氨酸蛋白激酶，可促进细胞存活。白藜芦醇和姜黄素等天然化合物具有抗脂肪形成活性并促进脂肪细胞凋亡。我们的数据表明它们抑制 PKC4II 表达。我们的数据进一步表明 PKC4II 是 Bcl2 介导的生存途径上游的信号激酶。我们建议确定细胞内靶标，该靶标对于脂肪细胞中的促生存途径至关重要，可以对其进行调节以诱导抗脂肪形成作用。在目标 3 中，将评估该假设的生理相关性，确定饮食诱导的肥胖小鼠模型 (C57BL/6) 中这些凋亡基因的表达水平，该小鼠模型喂食高脂肪饮食并辅以天然化合物或 PKC4II 特异性抑制剂。 通过表明凋亡基因的选择性剪接调节前脂肪细胞的分化和成熟，拟议的研究将为脂肪生成建立新的范式，并揭示肥胖治疗的新靶标。