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.

摘要 该项目的目标一直是并仍然是了解我们的生物化学基础， 观察到视黄醇结合蛋白2（RBP 2）在维持体重中具有未被怀疑的作用， 对葡萄糖激发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Rbp 2缺陷（Rbp 2-/-）小鼠的体重显著增加， 体重为白色脂肪组织（WAT），对葡萄糖激发的反应明显较差， 肝脏脂肪显著多于匹配的野生型（WT）同窝对照。这些表型完全 通过喂食高脂肪饮食6-7周的年轻的55日龄Rbp 2-/-和匹配的WT小鼠来重现。 我们发表的工作确定RBP 2和视黄醇结合蛋白4（RBP 4）都表达于 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。Rbp 2-/-小鼠在小鼠中显示升高的循环GIP水平。 对口服脂肪挑战的反应。我们进一步表明RBP 2结合长链不饱和2- 单酰基甘油（2-MAG）具有与视黄醇同样高的亲和力，因此是生理上的 相关的2-MAG结合蛋白以及类视色素结合蛋白。我们发现Rbp 4-/-小鼠具有 与对照组相比， WT对照。RBP 4定位于EEC分泌颗粒，并在刺激时与GIP一起沿着分泌。 培养的富含EEC的原代小鼠肠细胞。由于GIP水平升高与 在人类和动物模型中，体重和脂肪量，我们假设这有助于 Rbp 2-/-小鼠的代谢表型。我们提出了3个具体目标，探讨RBP 2的行动， RBP 4、类维生素A和2-MAG信号在调节EEC活性和GIP和GLP-1合成/分泌中的作用。 具体目标1将评估RBP 2、全反式维甲酸（ATRA）和ATRA-RAR的参与 信号传导和RBP 4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（ABDH 6和ADBH 12））和2-MAG作用（细胞表面大麻素受体1和2（Cb 1和Cb 2））。 Cb 2受体和GPR 119受体）调节K细胞对膳食营养素利用率的反应。这些研究将 使用与具体目标1相同的方法。 具体目标3将更好地了解RBP 2是否在GLP-1中具有直接作用 在小肠和结肠中的合成/分泌。尽管我们已经报道了 与GIP和K细胞不同，我们还没有系统地研究GLP-1或L细胞生物学， RBP 2在这种生物学中可能起什么作用的观点。