The Role of KBTBD2 in Lipodystrophy, Insulin Resistance, and Diabetes

KBTBD2 在脂肪营养不良、胰岛素抵抗和糖尿病中的作用

• 批准号: 10213315
• 负责人: Zhao Zhang
• 金额: $ 24.9万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10213315
• 关键词: 1-Phosphatidylinositol 3-Kinase; Adipocytes; Adipose tissue; Affect; Antibodies; BTB/POZ Domain; Binding; Biochemical; Biochemistry; Biological; Biological Assay; Blood Glucose; Body fat; Cells; Clustered Regularly Interspaced Short Palindromic Repeats; Complex; Cre-LoxP; Data; Defect; Development; Diabetes Mellitus; Diabetic mouse; Diet; Exhibits; Fasting; Fatty Liver; Fatty acid glycerol esters; Genes; Genetic; Genetic Screening; Genetic Transcription; Glucose; Growth; Homeostasis; Human; In Vitro; Insulin Resistance; Insulin Signaling Pathway; Knock-out; Lipids; Lipodystrophy; Liver; Maintenance; Malignant Neoplasms; Mass Spectrum Analysis; Mediating; Medical center; Mentors; Metabolic; Metabolic Diseases; Modification; Monoubiquitination; Mus; Muscle; Mutant Strains Mice; Mutate; Non-Insulin-Dependent Diabetes Mellitus; Nonsense Mutation; Obesity; Pathway interactions; Phase; Phenotype; Phosphorylation; Phosphotransferases; Physiologic Monitoring; Play; Polyubiquitination; Post-Translational Protein Processing; Post-Translational Regulation; Prevalence; Proteins; Public Health; Regulation; Research; Research Personnel; Role; Site; System; Testing; Tetanus Helper Peptide; Therapeutic; Time; Tissues; Training; Transplantation; Ubiquitination; Undifferentiated; Work; adipocyte differentiation; causal variant; conditional knockout; cullin-3; diabetes pathogenesis; diabetes risk; fasting glucose; global health; improved; in vivo; inhibitor/antagonist; insight; insulin sensitivity; insulin signaling; metabolic phenotype; mouse genetics; mouse model; new therapeutic target; novel; null mutation; overexpression; protein function; recruit; tool; ubiquitin-protein ligase

PROJECT SUMMARY Adipose tissue is critical for whole body energy homeostasis. Both obesity and lipodystrophy (caused by loss of fat) are associated with diabetes and insulin resistance. Our recent work identified a new mutant mouse, termed teeny, that exhibited growth retardation, lipodystrophy, extreme insulin resistance, severe diabetes with fasting glucose as high as 600-700 mg/dL, and fatty liver. The teeny phenotype is caused by a null mutation in the Kelch repeat and BTB (POZ) Domain containing 2 (KBTBD2), which has no previously assigned functions. We found that KBTBD2 operates as an E3 ubiquitin ligase to regulate the insulin signaling pathway by targeting the degradation of the regulatory subunit of phosphatidylinositol 3-kinase (PI3K), p85α. This proposal will further explore the role of KBTBD2 in lipodystrophy, insulin resistance, and diabetes, and will seek to identify mechanistically related regulators of diabetes and obesity. In the mentored K99 phase, mice will be generated to manipulate Kbtbd2 expression in different tissues to study its tissue-specific functions, and to dissect the role of each tissue in the development of teeny phenotype (Aim 1). I found that KBTBD2 harbors a YXXM motif, which may be phosphorylated in order to recruit p85α. The phosphorylation of KBTBD2 could explain why p85α is selectively degraded in different cells and tissues. This, in turn, would suggest that KBTDB2 itself might be subject to post-translational regulation depending upon tissue, developmental stage, and/or metabolic status. The focus of Aim 2 will be to study the post-translational modification of KBTBD2. In the independent R00 phase, I will further explore the biological consequences of the observed p85α mono-ubiquitination (Aim 3). The transcriptional suppression of Kbtbd2 in diet-induced obesity, leading to the accumulation of p85α, prompts us to search for deubiquitinases, which might be targeted by inhibitors to reduce the risk of diabetes in obesity. In preliminary studies, several candidate p85α deubiquitinases have been identified. To identify new genes that are involved in obesity and diabetes, we have established several forward genetic screens in mice and found interesting hits. Among these, a second BTB protein (RHOBTB2) may act within the overall framework we have built. In Aim 4, I will study the mechanism of deubiquitinases and other newly identified regulators in obesity and diabetes. Successful completion of the aims outlined in this proposal will improve our understanding of KBTBD2 and may provide new targets for diabetes treatment. To accomplish the proposed research, I will include Dr. Philipp Scherer (UT Southwestern Medical Center) as my co-mentor during the mentored K99 phase to gain more training in adipocyte and diabetes research. My mentor, Dr. Bruce Beutler, has established a unique forward genetic initiative with the ability to identify causative mutations in real time. I will continue working on newly identified regulators of obesity and diabetes from the established forward genetic screens in the independent R00 phase. This training will allow me to expand my expertise and help my transition into a successful independent academic researcher.

项目摘要 脂肪组织对于全身能量稳态至关重要。肥胖和脂肪营养不良（由 脂肪的损失与糖尿病和胰岛素抵抗有关。我们最近的工作确定了一种新的突变鼠标 被称为青少年，暴露于生长迟缓，脂肪营养不良，极端胰岛素抵抗，严重的糖尿病 禁食葡萄糖高达600-700 mg/dl，脂肪肝。青少年表型是由无效突变引起的 kelch重复和BTB（POZ）域，其中包含2（kbtbd2），没有先前分配的函数。 我们发现KBTBD2作为E3泛素连接酶起作用，以通过靶向来调节胰岛素信号通路 磷脂酰肌醇3-激酶（PI3K），p85α的调节亚基的降解。该提议将进一步 探索KBTBD2在脂肪营养不良，胰岛素抵抗和糖尿病中的作用，并将寻求识别 机械相关的糖尿病和肥胖调节剂。在物质的K99阶段，将生成小鼠 在不同时间内操纵KBTBD2表达以研究其组织特异性功能，并剖析该作用 在青少年表型发展中的每个组织（AIM 1）。我发现KBTBD2拥有YXXM图案， 可以磷酸化以募集p85α。 KBTBD2的磷酸化可以解释为什么P85α 在不同的细胞和组织中有选择地降解。反过来，这表明KBTDB2本身可能是 根据组织，发育阶段和/或代谢状况，受到翻译后调节的约束。 AIM 2的重点是研究KBTBD2的翻译后修饰。在独立r00阶段， 我将进一步探讨观察到的p85α单素化的生物学后果（AIM 3）。这 饮食引起的肥胖症中KBTBD2的转录抑制，导致p85α的积累，促使我们 寻找去泛素酶，抑制剂可能降低肥胖症患糖尿病的风险。 初步研究，已经鉴定出了几种候选p85α去泛素酶。识别新基因 参与肥胖和糖尿病，我们在小鼠中建立了几个正向遗传筛选，发现 有趣的热门歌曲。其中，第二个BTB蛋白（RHOBTB2）可能在整体框架内起作用 建造。在AIM 4中，我将研究去泛素酶和其他新确定的肥胖症调节剂的机制 糖尿病。成功完成本提案中概述的目标将提高我们对KBTBD2的理解 并可能为糖尿病治疗提供新的靶标。为了完成拟议的研究，我将包括博士 菲利普·谢勒（Philipp Scherer）（UT Southwestern Medical Center）是我在Meded K99阶段获得的同事 对脂肪细胞和糖尿病研究的更多培训。我的精神，布鲁斯·贝特勒（Bruce Beutler）博士已经建立了一个独特的 具有实时识别基础突变的能力的正向遗传倡议。我将继续工作 来自已建立的正向遗传筛选的肥胖和糖尿病的调节剂新确定 独立R00阶段。这项培训将使我能够扩大我的专业知识，并帮助我的过渡到 成功的独立学术研究员。