Hypothalamic regulation by thyroid hormone receptor phosphorylation

甲状腺激素受体磷酸化对下丘脑的调节

• 批准号: 10717820
• 负责人: ANTHONY N HOLLENBERG
• 金额: --
• 依托单位: RUTGERS BIOMEDICAL AND HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-17 至 2023-10-01
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10717820
• 关键词: Affect; Body Weight decreased; Cell Nucleus; Cells; Cre driver; Eating; Energy Metabolism; Fasting; Feedback; Female; Functional disorder; Human; Hyperphagia; Hyperthyroidism; Hypothalamic structure; Hypothyroidism; Knock-in Mouse; Knock-out; Laboratories; Labyrinth; Left; Leptin; Leptin resistance; LoxP-flanked allele; Malnutrition; Mammals; Mediating; Mediator; Metabolism; Mus; Mutation; N-terminal; Neurons; Nuclear Hormone Receptors; Nutritional; Obesity; Overnutrition; Pathway interactions; Pattern; Phospho-Specific Antibodies; Phosphorylation; Phosphorylation Site; Pituitary Gland; Protein Isoforms; Regulation; Resistance; Retina; Role; SF1; Seminal; Serine; Signal Pathway; Signal Transduction; Site; Structure of nucleus infundibularis hypothalami; THRA gene; THRB gene; Thyroid Gland; Thyroid Hormone Receptor; Thyroid Hormone Resistance Syndrome; Thyroid Hormones; Time; adenylate kinase; diet-induced obesity; feeding; genomic locus; hypothalamic-pituitary-thyroid axis; interest; knockout animal; male; man; mimetics; mouse model; novel; nutrient deprivation; nutrition; paraventricular nucleus; reduced food intake

Three major thyroid hormone receptor (THR) isoforms, expressed from two genetic loci (Thra and Thrb), are present in mammals: THRA1, THRB1, and THRB2. Thyroid hormone (TH) acting through THRs regulate food intake metabolism and the hypothalamic-pituitary-thyroid (HPT) axis in man. Our laboratories have long been interested in the THRB2 isoform as a central regulator of the hypothalamic-pituitary-thyroid (HPT) axis, given its unique and limited-expression pattern. We recently found that THRB2 is heavily phosphorylated by both TH and AMP kinase (AMPK) at an N-terminal serine site (S101-mouse, S102-human), not found in other THRs. Based on increased food intake, obesity, and TH resistance in mice carrying a mutation of this phosphorylation site (S101A), we hypothesize that an AMPK-dependent THRB2 S101 phosphorylation pathway in the hypothalamus suppresses food intake and the HPT axis. We also hypothesize that dysfunction of this pathway results in leptin resistance, increased food intake, and obesity (Fig. 1). Three closely related aims are proposed: Specific Aim 1: Functionally co-localize hypothalamic THRB2 and AMPK action on feeding. Both the arcuate (ARC) and ventromedial nucleus (VMN) regulate feeding in a THRB- and AMPK-dependent manner. To begin to functionally localize THRB2 action in the hypothalamus, THRB2 will be removed from the POMC neurons in the ARC and SF-1 neurons in the VMN using Thrb2 floxed mice and cell-specific Cre drivers. Cell- specific KO of AMPKa2 in the same neurons will also be performed to understand AMPKa2’s role in feeding and in the p-THRB2 pathway. Both male and female mice will be studied, given higher THRB2 expression in female HA-tagged THRB2 mice. Specific Aim 2: Determine the role of THRB2 phosphorylation in feeding and mediating hypothalamic leptin signaling. Previous studies have clearly demonstrated that leptin regulates both the HPT axis and feeding. A potential mediator of leptin action is p-THRB2, given that S101A mice demonstrate leptin resistance. A phospho-specific antibody was developed to probe this pathway further and will be used in a time- course study of THRB2 phosphorylation during the fed-fasting transition. Furthermore, a phosphomimetic S101D KI mouse model was generated to determine if this change protects against diet-induced obesity. Specific Aim 3: Define the locus of TRH regulation by THRB2 during fasting. While fasting-induced suppression of the HPT axis is mediated by reduced TRH expression in the paraventricular nucleus (PVN), it remains unknown how HPT axis suppression is maintained in the setting of low TH levels. Strikingly, S101A mice display resistance to fasting-induced TRH suppression, suggesting that THRB2 S101 phosphorylation is critical in the sensing of low TH levels. This aim will determine the locus of fasting-induced and TH-dependent TRH suppression by targeting neurons in the ARC and PVN. The mechanism of suppression will be explored further by studying if THRB2 phosphorylation is a common mechanism regulating the HPT axis and food intake.

由两个遗传基因座（THRA和THR）表达的三个主要甲状腺激素受体（THR）同工型是 存在于哺乳动物中：THA1，THRB1和THRB2。甲状腺骑马（TH）通过THRS调节食物 人类的摄入代谢和下丘脑 - 垂体 - 甲状腺（HPT）轴。我们的实验室长期以来一直是 考虑到其下丘脑 - 垂体 - 甲状腺（HPT）轴的THRB2同工型感兴趣 独特的和有限的表达模式。最近，我们发现Thrb2被TH和TH都大量磷酸化 N末端丝氨酸位点（S101-Mouse，S102-Human）的AMP激酶（AMPK），在其他THR中未发现。基于 携带这种磷酸化突变的小鼠的食物摄入量增加，肥胖和TH耐药性 站点（S101A），我们假设依赖AMPK的THRB2 S101磷酸化途径 下丘脑抑制食物摄入量和HPT轴。我们还假设这种功能障碍 途径会导致瘦素耐药性，食物摄入量增加和肥胖症（图1）。三个密切相关的目标 提出：特定目标1：在功能上共同定位下丘脑THRB2和AMPK对喂养方面的作用。两个都 弧形（ARC）和腹侧核（VMN）以THRB和AMPK依赖性方式调节喂养。 为了开始在下丘脑中将THRB2动作定位，将从POMC中删除THRB2 使用THRB2的小鼠和细胞特异性的CRE驱动器，VMN中的ARC和SF-1神经元中的神经元。细胞- 还将执行同一神经元中AMPKA2的特定KO，以了解AMPKA2在喂养和 在P-THRB2途径中。雄性和雌性小鼠都将研究雌性较高的THRB2表达 标记的Thrb2小鼠。特定目标2：确定THRB2磷酸化在喂养和介导中的作用 下丘脑瘦素信号传导。先前的研究清楚地表明，瘦素调节了HPT 鉴于S101A小鼠表现出瘦素 反抗。开发了一种磷酸特异性抗体，以进一步探测该途径，并将用于时间 在燃料过渡过程中THRB2磷酸化的课程研究。此外，一种磷酸化 生成S101D Ki小鼠模型，以确定这种变化是否可以防止饮食诱发的肥胖症。具体的 AIM 3：在禁食期间通过THRB2定义TRH调节的轨迹。而禁食引起的抑制 HPT轴是通过旁腔核（PVN）中的TRH表达降低介导的，它仍然未知。 HPT轴抑制保持在低水平的情况下。令人惊讶的是，S101A小鼠表现出对 禁食引起的TRH抑制，表明THRB2 S101磷酸化对低的灵敏度至关重要 级别。这个目标将通过靶向禁食诱导和Th依赖性TRH抑制的轨迹 ARC和PVN中的神经元。通过研究thrb2，将进一步探索抑制机制 磷酸化是调节HPT轴和食物摄入的常见机制。