The Function of Prohibitin / Annexin 2 Interaction in White Adipose Tissue

白色脂肪组织中抑制素/膜联蛋白 2 相互作用的功能

• 批准号: 8282866
• 负责人: Mikhail G Kolonin
• 金额: $ 32.18万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8282866
• 关键词: ANXA2 gene; Adipocytes; Adipose tissue; Adult; Annexins; Binding; Binding Proteins; Biology; Blood Vessels; Cardiovascular Diseases; Cell Culture Techniques; Cell Differentiation process; Cell membrane; Cell surface; Cells; Clinical Trials; Complex; Cytotoxic agent; Data; Development; Diet; Dominant-Negative Mutation; Endocytosis; Endothelial Cells; Endothelium; Enterochromaffin Cells; Fatty Acids; Glucose; Homeostasis; Hyperplasia; Hypertrophy; Impairment; Individual; Knockout Mice; Lipids; Lipolysis; Maintenance; Malignant Neoplasms; Measures; Mediating; Medical; Membrane Microdomains; Modeling; Mus; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Peptides; Physiological Processes; Play; Population; Process; Property; Protein Binding; Proteins; Role; Staging; Stem cells; Stromal Cells; Surface; Testing; Therapeutic; Tissue Expansion; Triglycerides; Vascularization; Wild Type Mouse; Work; angiogenesis; base; design; fatty acid oxidation; follow-up; glucose uptake; lipid biosynthesis; migration; mutant; novel; prohibitin; prospective; protein complex; public health relevance; receptor; socioeconomics; stromal progenitor; uptake

DESCRIPTION (provided by applicant): Obesity results from excessive expansion of white adipose tissue (WAT). We previously identified prohibitin (Phb) as a protein present on the endothelial cell (EC) surface selectively in WAT and have used a peptide CKGGRAKDC, which binds to Phb and undergoes Phb-mediated endocytosis, to direct a cytotoxic agent to mouse WAT as an experimental approach to obesity reversal. In order to better establish Phb as a prospective obesity therapy target, we have begun to characterize its currently undefined function in WAT. We identified annexin A2, also known as annexin II (Anx2), as a Phb-binding protein mimicked by the CKGGRAKDC peptide. While Anx2 has been previously shown to have a pro-angiogenic function, suggesting a role for Phb / Anx2 interaction in WAT endothelium, the role of Anx2 in adipose biology has not been explored. Our preliminary studies revealed Phb / Anx2 complex in cell membrane lipid rafts not only in WAT endothelium but also in adipocytes. Moreover, we discovered that Anx2 function is required during adipogenesis. Based on these observations, we hypothesize that in EC and in adipocytes Phb and Anx2 form a receptor complex that plays an important role in WAT development and homeostasis. To test our hypothesis, we will dissect the adipogenic and angiogenic functions of Anx2 and Phb in WAT based on mouse and cell culture models, as well as on our preliminary data identifying Phb / Anx2 interaction domains, in the following Specific Aims. (1) We will investigate the role of Anx2 in WAT development. By comparing individual WAT depots from Anx2-deficient and wild-type mice at different stages of development and upon diet-induced obesity induction, we will determine the importance of Anx2 for adipogenesis and WAT angiogenesis by assessing WAT expansion and adipocyte properties, as well as by analyzing WAT vascularization and the representation of WAT cell populations. (2) We will explore the function of Phb / Anx2 interaction in adipogenesis and WAT angiogenesis. In Sub-Aim 2A, we will determine why lipid droplet accumulation is impaired in adipocytes upon perturbation of Anx2 function. By using differentiating adipocytes either completely lacking Anx2 or designed to be deficient in Phb / Anx2 binding, we will assess changes in expression and localization of proteins marking adipogenesis and will measure glucose and fatty acid uptake, as well as lipolysis. In Sub-Aim 2B, we will test the role of Phb / Anx2 interaction in WAT vasculature by assessing proliferation, migration, and vasculature formation capacity of EC either completely lacking Anx2 or designed to be deficient in Phb / Anx2 binding. As a result, we will establish the role of the cell surface interaction between Phb and Anx2 in WAT. This will contribute to our understanding of the mechanisms governing WAT tissue expansion and provide valuable information on the biology of this protein complex potentially useful as a target of anti-obesity therapeutics. PUBLIC HEALTH RELEVANCE: Obesity is positively associated with cardiovascular disease, type 2 diabetes, and cancer, thus representing a socioeconomic and medical problem of escalating concern. Our study will contribute to the understanding of mechanisms that control adipose cell differentiation and blood vessel formation during the expansion of white adipose tissue responsible for obesity. The molecular interaction between prohibitin and annexin 2 uncovered by our work is a potential target for anti-obesity therapy, and this study is a next step toward prospective clinical trials.

描述（由申请人提供）：肥胖是由于白色脂肪组织（WAT）过度膨胀造成的。我们之前将抑制素 (Phb) 鉴定为 WAT 中选择性存在于内皮细胞 (EC) 表面的蛋白质，并使用肽 CKGGRAKDC（它与 Phb 结合并经历 Phb 介导的内吞作用）将细胞毒性剂引导至小鼠 WAT，作为逆转肥胖的实验方法。为了更好地将 Phb 确立为前瞻性肥胖治疗靶点，我们已经开始描述其在 WAT 中目前未定义的功能。我们鉴定出膜联蛋白 A2，也称为膜联蛋白 II (Anx2)，是一种由 CKGGRAKDC 肽模拟的 Phb 结合蛋白。虽然 Anx2 先前已被证明具有促血管生成功能，表明 Phb / Anx2 相互作用在 WAT 内皮中发挥作用，但 Anx2 在脂肪生物学中的作用尚未被探索。我们的初步研究表明，Phb / Anx2 复合物不仅存在于 WAT 内皮细胞膜脂筏中，而且存在于脂肪细胞中。此外，我们发现脂肪生成过程中需要 Anx2 功能。基于这些观察，我们假设在 EC 和脂肪细胞中 Phb 和 Anx2 形成受体复合物，在 WAT 发育和体内平衡中发挥重要作用。为了检验我们的假设，我们将根据小鼠和细胞培养模型以及我们识别 Phb / Anx2 相互作用域的初步数据，在以下具体目标中剖析 WAT 中 Anx2 和 Phb 的脂肪生成和血管生成功能。 (1)我们将研究Anx2在WAT发展中的作用。通过比较 Anx2 缺陷小鼠和野生型小鼠在不同发育阶段和饮食诱导肥胖诱导后的个体 WAT 库，我们将通过评估 WAT 扩张和脂肪细胞特性，以及分析 WAT 血管化和 WAT 细胞群的代表性，确定 Anx2 对脂肪生成和 WAT 血管生成的重要性。 (2)我们将探讨Phb/Anx2相互作用在脂肪生成和WAT血管生成中的功能。在子目标 2A 中，我们将确定为什么 Anx2 功能扰动时脂肪细胞中的脂滴积累会受到损害。通过使用分化完全缺乏 Anx2 或设计为缺乏 Phb / Anx2 结合的脂肪细胞，我们将评估标记脂肪生成的蛋白质表达和定位的变化，并测量葡萄糖和脂肪酸的摄取以及脂肪分解。在子目标 2B 中，我们将通过评估完全缺乏 Anx2 或设计为缺乏 Phb / Anx2 结合的 EC 的增殖、迁移和脉管系统形成能力来测试 Phb / Anx2 相互作用在 WAT 脉管系统中的作用。因此，我们将确定 Phb 和 Anx2 之间的细胞表面相互作用在 WAT 中的作用。这将有助于我们了解控制 WAT 组织扩张的机制，并提供有关该蛋白质复合物生物学的有价值的信息，该蛋白质复合物可能可用作抗肥胖治疗的靶点。 公共卫生相关性：肥胖与心血管疾病、2 型糖尿病和癌症呈正相关，因此是一个日益引起关注的社会经济和医学问题。我们的研究将有助于了解在导致肥胖的白色脂肪组织扩张过程中控制脂肪细胞分化和血管形成的机制。我们的工作发现的抑制素和膜联蛋白 2 之间的分子相互作用是抗肥胖治疗的潜在靶标，这项研究是前瞻性临床试验的下一步。