RBP2 Biology and Pathobiology

RBP2 生物学和病理学

• 批准号: 10736946
• 负责人: WILLIAM S BLANER
• 金额: $ 68.29万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-06-15 至 2027-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10736946
• 关键词: 2-arachidonylglycerol; Adipose tissue; Adult; Affect; Affinity; All-Trans-Retinol; Animal Model; Binding; Binding Proteins; Biochemical; Biology; Body Weight; CNR1 gene; CNR2 gene; Cell Differentiation process; Cell Proliferation; Cell physiology; Cell surface; Cells; Cellular biology; Chromatin; Colon; Complex; Desire for food; Development; Diet; Endocannabinoids; Energy Metabolism; Enteroendocrine Cell; Enzymes; Fasting; Fatty acid glycerol esters; G-Protein-Coupled Receptors; GPR119 receptor; Genes; Genetic Transcription; Glucose; Glycerol; Goals; Grant; Hepatic; High Fat Diet; Hormone secretion; Hydrolase; Immune response; Impairment; In Vitro; Inflammation; Intestines; Killer Cells; Knockout Mice; L Cells; Ligands; Link; Maintenance; Mediating; Metabolic; Metabolic Diseases; Metabolism; Methodology; Molecular Weight; Monoacylglycerol Lipases; Monoglycerides; Motivation; Mus; Nerve Degeneration; Nociception; Nuclear Hormone Receptors; Nutrient availability; Oral; Organoids; Pathway interactions; Phenotype; Physiological; Proliferating; Proteins; Publishing; RBP4 gene; Reporting; Retinaldehyde; Retinoic Acid Binding; Retinoic Acid Receptor; Retinoic Acid Response Element; Retinoids; Retinol Binding Proteins; Rewards; Role; Secretory Vesicles; Signal Pathway; Signal Transduction; Small Intestines; Smooth Muscle; Tretinoin; Triglycerides; Vitamin A; Weight Gain; Wild Type Mouse; Work; aldehyde dehydrogenases; anandamide; cell growth; cell type; cognitive function; dietary; gastric inhibitory polypeptide receptor; glucagon-like peptide 1; glucose metabolism; hormone regulation; human model; in vivo; incretin hormone; interest; lipid metabolism; lipoprotein lipase; metabolic phenotype; mood regulation; neurogenesis; oxidation; prevent; response; retinoic acid receptor alpha; retinoic acid receptor gamma; uptake

ABSTRACT The goal of this project has been and remains to gain understanding of the biochemical basis for our observation that retinol-binding protein 2 (RBP2) has an unsuspected role in the maintenance of body weight, normal responses to a glucose challenge, and normal fasting hepatic triglyceride levels. We found that when maintained solely on a control chow diet, 6-7-month-old Rbp2-deficient (Rbp2-/-) mice accrue significantly more body weight as white adipose tissue (WAT), respond significantly less well to a glucose challenge, and possess significantly more hepatic fat than matched wild type (WT) littermate controls. These phenotypes were fully recapitulated by younger 55-day old Rbp2-/- and matched WT mice fed a high fat diet for 6-7 weeks. Our published work establishes that both RBP2 and retinol-binding protein 4 (RBP4) are expressed in enteroendocrine cells (EECs) within the gut, including by glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) expressing cells. Rbp2-/- mice show elevated circulating GIP levels in response to an oral fat challenge. We further showed that RBP2 binds long-chain unsaturated 2- monoacylglycerol (2-MAGs) with an equally high affinity as it does retinol and is consequently a physiologically relevant 2-MAG-binding protein as well as a retinoid-binding protein. We identified that Rbp4-/- mice have significantly diminished circulating GIP concentrations both fasting and after an oral fat challenge compared to WT controls. RBP4 localizes to EEC secretory granules and is co-secreted along with GIP upon stimulation of cultured EEC-enriched primary mouse intestinal cells. Since elevated GIP levels are associated with increased body weight and adipose mass in both humans and animal models, we hypothesize that this contributes to the metabolic phenotypes seen for Rbp2-/- mice. We are proposing 3 Specific Aims exploring the actions of RBP2, RBP4, retinoid- and 2-MAG signaling in regulating EEC activities and synthesis/secretion of GIP and GLP-1. Specific Aim 1 will assess the involvement of RBP2, all-trans-retinoic acid (ATRA) and ATRA-RAR signaling, and RBP4 in modulating EEC responses. This entails both in vivo and in vitro studies. Specific Aim 2 will assess the involvement of 2-MAGs and enzymes responsible for 2-MAG synthesis (diacylglycerol lipase (DAGL)), 2-MAG degradation (monoacylglycerol lipase (MAGL) and α/β hydrolase domain 6 and 12 (ABDH6 and ADBH12)) and 2-MAG actions (the cell surface cannabinoid receptors 1 and 2 (Cb1 and Cb2) and GPR119 receptors) in modulating K-cell responses to dietary nutrient availability. These studies will make use of the same methodologies employed in Specific Aim 1. Specific Aim 3 will provide greater understanding of whether RBP2 has a direct role in GLP-1 synthesis/secretion in both the small intestine and in the colon. Although we have reported the presence of RBP2 protein in L-cells, unlike GIP and K-cells, we have not systematically studied GLP-1 or L-cell biology from the perspective of what role RBP2 may have in this biology.

抽象的 该项目的目标一直是并且仍然是为了了解我们的生物化学基础 观察到视黄醇结合蛋白 2 (RBP2) 在维持体重方面具有意想不到的作用， 对葡萄糖挑战的正常反应和正常的空腹肝甘油三酯水平。我们发现当 仅维持对照食物饮食，6-7 个月大的 Rbp2 缺陷 (Rbp2-/-) 小鼠的累积量显着增加 体重为白色脂肪组织（WAT），对葡萄糖挑战的反应明显较差，并且具有 与匹配的野生型（WT）同窝对照相比，肝脂肪显着增加。这些表型完全 由 55 天龄的年轻 Rbp2-/- 和匹配的 WT 小鼠进行重述，喂食高脂肪饮食 6-7 周。 我们发表的工作表明，RBP2 和视黄醇结合蛋白 4 (RBP4) 均在 肠道内的肠内分泌细胞 (EEC)，包括葡萄糖依赖性促胰岛素多肽 (GIP) 和胰高血糖素样肽 1 (GLP-1) 表达细胞。 Rbp2-/- 小鼠的循环 GIP 水平升高 对口腔脂肪挑战的反应。我们进一步表明 RBP2 结合长链不饱和 2- 单酰基甘油 (2-MAG) 与视黄醇具有同样高的亲和力，因此在生理学上是一种 相关的 2-MAG 结合蛋白以及类视黄醇结合蛋白。我们发现 Rbp4-/- 小鼠具有 与相比，空腹和口服脂肪挑战后循环 GIP 浓度显着降低 WT 控制。 RBP4 定位于 EEC 分泌颗粒，并在刺激后与 GIP 一起共同分泌。 培养富含 EEC 的原代小鼠肠细胞。由于 GIP 水平升高与 人类和动物模型中的体重和脂肪量，我们假设这有助于 Rbp2-/- 小鼠的代谢表型。我们提出 3 个具体目标来探索 RBP2 的作用， RBP4、类视黄醇和 2-MAG 信号传导调节 EEC 活性以及 GIP 和 GLP-1 的合成/分泌。 具体目标 1 将评估 RBP2、全反式视黄酸 (ATRA) 和 ATRA-RAR 的参与 信号传导和 RBP4 调节 EEC 反应。这需要体内和体外研究。 具体目标 2 将评估 2-MAG 和负责 2-MAG 合成的酶的参与 （二酰基甘油脂肪酶 (DAGL)）、2-MAG 降解（单酰基甘油脂肪酶 (MAGL) 和 α/β 水解酶结构域 6 和 12（ABDH6 和 ADBH12））和 2-MAG 作用（细胞表面大麻素受体 1 和 2（Cb1 和 Cb2) 和 GPR119 受体) 调节 K 细胞对膳食营养可用性的反应。这些研究将 使用特定目标 1 中采用的相同方法。 具体目标 3 将更好地了解 RBP2 是否在 GLP-1 中具有直接作用 在小肠和结肠中合成/分泌。尽管我们已经报告了存在 L 细胞中的 RBP2 蛋白，与 GIP 和 K 细胞不同，我们尚未系统地研究 GLP-1 或 L 细胞生物学 RBP2 在此生物学中可能发挥什么作用的观点。