Balance between HNF4a isoforms in the carbohydrate-lipid metabolic switch

碳水化合物-脂质代谢开关中 HNF4a 亚型之间的平衡

• 批准号: 10367664
• 负责人: FRANCES M. SLADEK
• 金额: $ 42.92万
• 依托单位: UNIVERSITY OF CALIFORNIA RIVERSIDE
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-25 至 2026-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10367664
• 关键词: 5' -AMP-activated protein kinase; Ablation; Acetylation; Adult; Aging; American; Biogenesis; Brain; Carbohydrates; Cardiovascular system; Chemicals; Communities; Data; Deacetylase; Deacetylation; Dementia; Diabetes Mellitus; Diet; Diurnal Rhythm; Drug Prescriptions; Effectiveness; Energy Metabolism; Enzymes; Equilibrium; Estrogen Receptor alpha; Estrogens; Exons; Fasting; Fatty Liver; Fatty acid glycerol esters; Female; Fetal Liver; Gene Expression; General Population; Genes; Gluconeogenesis; Glucose; Goals; HNF4A gene; Health; Hepatocyte; High Fat Diet; In Vitro; Intermittent fasting; Intestines; Ketone Bodies; Kidney; Knockout Mice; Light; Lipids; Liver; Liver diseases; Malignant neoplasm of liver; Maps; Mass Spectrum Analysis; Mediating; Medical; Metabolic; Metabolic Diseases; Metabolism; Metformin; Mitochondria; Molecular; Mus; Mutate; Neurologic; Nuclear Receptors; Obesity; Obesity Epidemic; Pathway interactions; Phosphorylation; Phosphorylation Site; Phosphotransferases; Physiological; Play; Process; Protein Isoforms; Protein Kinase; Proteins; Research; Role; SIRT1 gene; Source; Time; Tissues; Wild Type Mouse; Work; base; carbohydrate metabolism; dieting; experience; experimental study; feeding; glucose metabolism; hepatocyte nuclear factor; in vivo; inhibitor/antagonist; ketogenesis; ketogenic diet; ketogentic; lipid metabolism; male; maturity onset diabetes of the young; nervous system disorder; promoter; response; sex; sugar; translational impact; trend; weight loss program

Abstract Hepatocyte Nuclear Factor 4α (HNF4α), a master regulator of liver-specific gene expression, is regulated by two promoters (P1 and P2) which drive expression of two groups of HNF4α isoforms referred to as HNF4α1 and HNF4α7. HNF4α is a known regulator of gluconeogenesis and mutated in maturity onset diabetes of the young one (MODY1). Conventionally, it was thought that HNF4α1, but not HNF4α7, is expressed in the normal adult liver, while HNF4α1 is downregulated and HNF4α7 is upregulated in liver cancer. Now, research in our lab reveals a previously undescribed role for HNF4α7 in the normal adult mouse liver – one involved in the diurnal variations of lipid and carbohydrate metabolism. More specifically, HNF4α1 appears to be a major driver of gluconeogenesis while HNF4α7 is a driver of ketogenesis: we propose that alterations in the levels of the HNF4α isoforms during the day flip the molecular switch between the two. Our preliminary data also show that HNF4α7 is required for increased levels of circulating ketone bodies in female mice. AMP-Activated Protein Kinase (AMPK), an energy-sensing enzyme, has been shown to phosphorylate HNF4α1 in vitro, but effects in vivo and on HNF4α7 are not known. SIRT1 is a deacetylase that works with AMPK to regulate glucose and lipid metabolism. HNF4α1 is known to be acetylated and our preliminary data suggest that HNF4α7 but not HNF4α1 interacts with SIRT1. Here, we propose to use HNF4α1-expressing (α1HMZ) and HNF4α7-expressing exon swap mice (α7HMZ) to determine the physiological function of the HNF4α isoforms in the switch between gluconeogenesis and ketogenesis, and to characterize the impact of sex on those functions. In Aim 1, we will determine whether intermittent fasting and a ketogenic diet increase the levels of HNF4α7 in the liver, and whether the increase occurs in all hepatocytes, or just a subset. We will determine the consequences of HNF4α7 on gene expression. Kidney and intestines will also be explored. In Aim 2, we will determine whether the AMPK pathway acts in a differential fashion on the HNF4α isoforms to help flip the metabolic switch. Phosphorylation by AMPK and deacetylation by SIRT1 will be explored. Finally, in Aim 3, we will determine whether the estrogen pathway impacts the HNF4α isoforms in female mice and determine the consequences for the metabolic switch. Our compelling preliminary data that the HNF4α isoforms are involved in the switch between gluconeogenesis and ketogenesis shed new light on this basic metabolic process that occurs on a daily basis and under conditions of feeding and fasting. The results from this proposal will illuminate not only the molecular mechanism underlying the switch but also how that mechanism is impacted by sex. The proposed studies have the potential to impact our understanding of numerous metabolic diseases, including diabetes, obesity, fatty liver disease and cancer. Finally, given the fact that ketone bodies serve as a source of fuel for the brain, our results could have a broader impact, including on neurological diseases, such as dementia.

摘要 肝细胞核因子4α（HNF 4 α）是肝脏特异性基因表达的主要调节因子，受以下因素的调节： 两个启动子（P1和P2）驱动两组HNF 4 α亚型（称为HNF 4 α1）的表达 HNF 4 α7。HNF 4 α是一种已知的胚胎发生调节因子，在成年型糖尿病患者中发生突变。 年轻的一个（MODY 1）。传统上，认为HNF 4 α1，而不是HNF 4 α7，在正常人的肝细胞中表达。 在成人肝脏中，HNF 4 α1下调，HNF 4 α7上调。我们实验室的研究 揭示了HNF 4 α7在正常成年小鼠肝脏中以前未描述的作用-一种参与昼夜节律的作用， 脂质和碳水化合物代谢的变化。更具体地说，HNF 4 α1似乎是一个主要的驱动程序， HNF 4 α7是生酮的驱动因素：我们认为HNF 4 α 7水平的改变， 在白天的同种型在两者之间翻转分子开关。我们的初步数据还表明，HNF 4 α7 是雌性小鼠循环酮体水平升高所必需的。amp激活的蛋白激酶 AMPK是一种能量敏感酶，在体外可使HNF 4 α1磷酸化，但在体内和 HNF 4 α7的作用机制尚不清楚。SIRT 1是一种脱乙酰酶，与AMPK一起调节葡萄糖和脂质 新陈代谢.已知HNF 4 α1是乙酰化的，我们的初步数据表明HNF 4 α7而不是HNF 4 α1是乙酰化的。 与SIRT 1相互作用。在这里，我们建议使用HNF 4 α1表达外显子（α1HMZ）和HNF 4 α7表达外显子（α 1HMZ）， 交换小鼠（α 7 HMZ），以确定HNF 4 α亚型在 胚胎发育和生酮，并描述性别对这些功能的影响。在目标1中，我们 确定间歇性禁食和生酮饮食是否会增加肝脏中HNF 4 α7的水平， 无论这种增加发生在所有肝细胞中，还是仅发生在一个子集中。我们将确定HNF 4 α7 对基因表达的影响肾脏和肠道也将被探索。在目标2中，我们将确定AMPK是否 HNF 4 α通路以不同的方式作用于HNF 4 α亚型，以帮助翻转代谢开关。磷酸化 通过AMPK和SIRT 1的脱乙酰化将被探索。最后，在目标3中，我们将确定雌激素 通路影响雌性小鼠中的HNF 4 α亚型，并确定代谢转换的后果。 我们令人信服的初步数据表明，HNF 4 α亚型参与了 异生和酮生为这一每天发生的基本代谢过程提供了新的线索 在进食和禁食的条件下。这项提议的结果不仅将阐明分子 转换背后的机制，以及性别如何影响这种机制。拟议的研究有 可能会影响我们对许多代谢疾病的理解，包括糖尿病，肥胖，脂肪肝， 疾病和癌症。最后，考虑到酮体是大脑的燃料来源，我们的研究结果 可能会产生更广泛的影响，包括对痴呆症等神经系统疾病的影响。