The hepatic function of cholesterol sulfotransferase 2B1b (SULT2B1b)in energy met

描述（由申请人提供）：胆固醇磺酰基转移酶SULT2B1b是一种胞质磺酰基转移酶，以其磺化胆固醇和氧甾醇的活性而闻名。代谢综合征，通常表现为肥胖和胰岛素抵抗型2型糖尿病，是一个主要的健康问题。糖脂代谢失调在肥胖和2型糖尿病中起着重要的致病作用。虽然SULT2B1b催化胆固醇硫酸化的活性已被证实，但SULT2B1b及其酶促副产物硫酸胆固醇（CS）在能量代谢和代谢综合征中的作用仍然未知。我们的初步结果表明：1)SULT2B1b在肥胖小鼠和从禁食到进食的过渡状态中被诱导；2) SULT2B1b和CS抑制肝细胞糖异生；3) SULT2B1b和CS特异性抑制HNF4?的糖异生活性；4)在HFD和ob/ob模型中，CS治疗抑制糖异生，改善胰岛素敏感性；5)转基因过表达SULT2B1b可改善HFD模型的代谢功能；6)瘦素是SULT2B1b代谢益处的潜在影响因子；7) SULT2B1b和CS抑制乙酰辅酶A合成酶2 （Acss2）的表达，降低HNF4？，引起HNF4?的核排斥；而强制表达Acss2可消除CS对HNF4的抑制作用；8)下调HNF4？消除了CS对体外糖异生的抑制作用；9) SULT2B1b是潜在的HNF4？靶基因，为糖异生负反馈调控提供了可能的机制。基于我们的初步数据，我们假设胆固醇磺基转移酶SULT2B1b在抑制糖异生和减轻代谢性疾病方面具有以前未被认识到的作用。从机制上说，SULT2B1b的代谢益处可能是通过其酶促副产物硫酸胆固醇（CS）和靶向糖异生转录因子HNF4的乙酰化和核易位来实现的。我们还假设SULT2B1是一种HNF4？靶基因，它代表了一种限制HNF4?糖异生活性的负反馈机制。我们预计瘦素是SULT2B1b改善代谢功能的潜在效应因子。通过使用肝脏特异性SULT2B1b转基因小鼠，结合HFD和肥胖和2型糖尿病的ob/ob模型，我们提出了三个特定目的来验证我们的假设：1)确定肝脏特异性SULT2B1b过表达是否抑制肥胖和2型糖尿病的ob/ob模型；2)确定SULT2B1b和CS抑制糖异生的分子机制；3)确定HNF4是否诱导SULT2B1b ？代表了糖异生负反馈调控的潜在机制。据我们所知，本研究首次尝试综合评价SULT2B1b及其酶促副产物CS在体内能量代谢中的内源性和肝脏功能。本研究结果可能确立SULT2B1b作为新的治疗靶点，CS作为治疗代谢性疾病的药物。

DESCRIPTION (provided by applicant): The cholesterol sulfotransferase SULT2B1b is a cytosolic sulfotransferase best known for its activity in sulfonating cholesterol and oxysterols. Metabolic syndrome, often manifested as obesity and insulin resistant type 2 diabetes, is a major health concern. The dysregulation of glucose and lipid metabolism plays an important pathogenic role in obesity and type 2 diabetes. Although the activity of SULT2B1b in catalyzing the sulfation of cholesterol has been documented, the role of SULT2B1b and its enzymatic byproduct cholesterol sulfate (CS) in energy metabolism and metabolic syndrome remains largely unknown. Our preliminary results showed that: 1) SULT2B1b was induced in obese mice and during the transition from the fasted to the fed state; 2) SULT2B1b and CS inhibited gluconeogenesis in hepatic cells; 3) SULT2B1b and CS specifically inhibited the gluconeogenic activity of HNF4?; 4) Treatment with CS inhibited gluconeogenesis and improved insulin sensitivity in both HFD and ob/ob models; 5) Transgenic overexpression of SULT2B1b improved metabolic functions in the HFD model; 6) Leptin is a potential effector for the metabolic benefit of SULT2B1b; 7) SULT2B1b and CS suppressed the expression of acetyl-coenzyme A synthetase 2 (Acss2), decreased the acetylation of HNF4?, and caused the nuclear exclusion of HNF4?; whereas a forced expression of Acss2 abolished the inhibitory effect of CS on HNF4?; 8) Down-regulation of HNF4? abolished the inhibitory effect of CS on gluconeogenesis in vitro; and 9) SULT2B1b is a potential HNF4? target gene, providing a possible mechanism of negative feedback regulation of gluconeogenesis. Based on our preliminary data, we hypothesize that the cholesterol sulfotransferase SULT2B1b has a previously unrecognized role in inhibiting gluconeogenesis and alleviating metabolic disease. Mechanistically, the metabolic benefit of SULT2B1b may have been achieved through its enzymatic byproduct cholesterol sulfate (CS) and by targeting the acetylation and nuclear translocation of the gluconeogenic transcriptional factor HNF4?. We also hypothesize that the SULT2B1 is a HNF4? target gene, which represents a negative feedback mechanism to limit the gluconeogenic activity of HNF4?. We anticipate that leptin is a potential effector of SULT2B1b in improving metabolic functions. By using the liver-specific SULT2B1b transgenic mice, in conjunction with HFD and ob/ob models of obesity and type 2 diabetes, we propose three Specific Aims to test our hypotheses: 1) To determine whether the liver-specific overexpression of SULT2B1b inhibits the ob/ob model of obesity and type 2 diabetes; 2) To determine the molecular mechanism by which SULT2B1b and CS inhibit gluconeogenesis; and 3) To determine whether the induction of SULT2B1b by HNF4? represents a potential mechanism of negative feedback regulation of gluconeogenesis. To our knowledge, this study represents the first attempt to comprehensively evaluate the endobiotic and hepatic function of SULT2B1b and its enzymatic byproduct CS in energy metabolism in vivo. Results from this study may establish SULT2B1b as a novel therapeutic target and CS as a therapeutic agent to manage metabolic disease.