细胞因子诱导的SH2结构包含蛋白（CISH）调控肝脏脂质代谢的新功能和机制研究

The dysregulation of hepatic lipid metabolism is a large contributor to nonalcoholic fatty liver disease (NAFLD). But the specific molecular mechanism of NAFLD is not clear. Our previous study demonstrated that leucine deprivation inhibites hepatic lipogenesis. Then a high-throughput gene microarray was used to screen the differentially expressed genes in the liver of mice under leucine deprivation, which were proposed to be involved in regulating hepatic lipid metabolism. The cytokine-inducible SH2-containing gene (CISH), which was differentially expressed in the liver of leucine-deprived mice, was identified by gene chip analysis. CISH is involved in the regulation of various processes, including proliferation and tumorigenesis. A role of CISH in the control of hepatic lipid metabolism, however, remains completely unknown. Our preliminary results showed that the expression of CISH was up-regulated in the livers of mice with fatty liver. Therefore, we suspect that CISH plays an important role in the regulation of hepatic lipid metabolism. The objectives of this research are to investigate the involvement of CISH in regulating hepatic lipid metabolism and elucidate the underlying mechanisms and explore upstream signaling pathway of CISH. We will explore these in various cell models, liver-specific CISH knockout mice, db/db mice and mice under various nutrition conditions such as amino acids, high fat, high fructose by using adenovirus. This work will reveal the novel function of CISH in regulating hepatic lipid metabolism, help us to understand the pathogenesis of NAFLD and offer new strategies for prevention and treatment of NAFLD.

肝脏脂质代谢紊乱是非酒精性脂肪肝发生的重要原因，但相关分子机制还不清楚。我们实验室前期工作发现亮氨酸缺乏可抑制肝脏脂质合成，申请人利用基因芯片进一步发现该条件下肝脏中多个基因表达发生改变，推测这些基因有可能参与调控肝脏脂质代谢。细胞因子诱导的SH2结构包含蛋白（CISH）是基因芯片筛选出的表达受亮氨酸缺乏调控的因子之一。以往研究报道CISH可影响细胞增殖和肿瘤发生，但其可否调控肝脏脂质代谢尚无报道。申请人前期研究发现CISH在脂肪肝小鼠肝脏中表达显著增加，推测CISH有可能具有调控肝脏脂质代谢的新功能。本项目将探讨该可能性：拟利用细胞模型和CISH肝脏特异敲除小鼠，结合尾静脉腺病毒注射技术，探讨CISH对肝脏脂质代谢的调控及分子机制；并利用db/db及不同饮食喂养的小鼠，探讨调控CISH表达的上游信号通路。此项目有助于认识CISH的生理功能，理解非酒精性脂肪肝的发病机制并提供防治的新策略。

肝脏脂质代谢紊乱是非酒精性脂肪肝发生的重要原因，但相关分子机制还不清楚。我们实验室前期工作发现亮氨酸缺乏可抑制肝脏脂质合成，申请人利用基因芯片进一步发现该条件下肝脏中多个基因表达发生改变，推测这些基因有可能参与调控肝脏脂质代谢。细胞因子诱导的SH2结构包含蛋白（CISH）是基因芯片筛选出的表达受亮氨酸缺乏调控的因子之一。以往研究报道CISH可影响细胞增殖和肿瘤发生，但其可否调控肝脏脂质代谢尚无报道。本项目研究发现，短期亮氨酸缺乏小鼠肝脏中CISH表达降低，非酒精性脂肪肝模型高脂喂养小鼠肝脏中CISH表达升高。Hepa1-6和原代肝细胞上干扰CISH表达可减少细胞甘油三酯积累，过表达CISH则增加细胞甘油三酯积累。野生型小鼠体内利用病毒干扰CISH表达减少肝脏脂滴聚集。然而，野生型小鼠体内利用病毒过表达CISH也减少肝脏中三油甘脂的含量，肝脏过表达CISH对db/db小鼠肝脏脂质代谢的作用并不大。此外，CISH肝脏特异性敲除小鼠肝脏中脂质代谢未发现异常。因此后续探讨了CISH对糖代谢的作用。研究发现肝脏CISH在禁食期间表达降低；细胞水平上过表达CISH降低糖异生，降低CISH表达则促进糖异生；CISH肝脏特异性敲除小鼠糖异生增强；CISH通过P-CREB调节肝脏糖异生过程。此项目增加了对CISH生理功能的认识，为营养学干预治疗代谢疾病增加了新的内容。