2型糖尿病易感基因SLC16A11的功能与分子机制研究

The wealth of data being generated by human genetics nowadays is providing new opportunities to discover novel genetic contributors to many human diseases, including type II diabetes. Genetic studies in Mexican and other Latin American populations has identified a novel locus associated with high risk of type II diabetes with the strongest signal of association spanning the SLC16A11 gene. Individuals that carry one copy of the risk haplotype can have predicted 25% increase in developing diabetes. SLC16A11 encodes a solute carrier belonging to the monocarboxylic acid transporters family, which localizes at endoplasmic reticulum, and is predicted to be involved in metabolites transportation, thus sensing the nutrient signal. However, the function of SLC16A11 is poorly characterized and the substrate is unknown. In order to better characterize the molecular pathway of SLC16A11 and to identify the substrate, we propose to use genome editing with cutting-edge clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems to knock out the SLC16A11 gene in human pluripotent stem cells, knock out the Slc16a11 gene in either the whole body or conditionally in metabolic tissues in mouse models. We will then use differentiated cells from human pluripotent stem cells, primary tissues, and whole animals to comprehensively study the effects of SLC16A11 on metabolic phenotypes and metabolomics. In doing this, we seek to understand the genetic roots of type II diabetes, and at the same time establish a rapid and efficient multi-species approach with which to study the effects of metabolic genes discovered by gene mapping experiments.

人类基因组学测序为揭开2型糖尿病的根本遗传致病因素提供了新的视角。对糖尿病高发特殊人群的全基因组关联分析发现，在基因SLC16A11区域存在糖尿病易感突变 —— 一个拷贝的突变对应25%糖尿病发病率的增长，提示SLC16A11基因在糖尿病发生中起关键调控作用。SLC16A11编码内质网跨膜转运子，预测参与代谢产物转运和细胞营养状态感应，但其转运底物和功能基本未知。为深入研究SLC16A11的功能和作用机制，我们拟通过CRISPR基因组编辑技术建立SLC16A11基因敲除的人全能干细胞株、全身或者组织特异性SLC16A11基因敲除小鼠 ，综合人全能干细胞疾病模型和多种遗传突变小鼠模型，从机体整体代谢，组织功能，细胞表型多个层面分析SLC16A11的代谢调控功能，并通过小分子代谢产物组学分析，进一步鉴定SLC16A11的转运底物。研究发现将对深入解析2型糖尿病的遗传致病因素有重要意义。

项目背景：人类基因组学测序为揭开2型糖尿病的根本遗传致病因素提供了新的视角。对糖尿病高发 特殊人群的全基因组关联分析发现，在基因SLC16A11区域存在糖尿病易感突变 —— 一个拷贝 的突变对应25%糖尿病发病率的增长，提示SLC16A11基因在糖尿病发生中起关键调控作用。SLC 16A11编码内质网跨膜转运子，预测参与代谢产物转运和细胞营养状态感应，但其功能基本未知。.主要研究内容：为深入研究SLC16A11的功能和作用机制，我们通过CRISPR基因组编辑技术建立全身SLC16A11基因敲除小鼠 ，并通过AAV病毒载体引入携带糖尿病易感突变的SLC16A11突变体，同时综合人肝脏细胞模型和遗传突变小鼠模型，从机体整体代谢，组织功能，细胞表型多个层面分析SLC16A11的代谢调控功能。.重要结果和关键数据：我们发现：1）小鼠全身性敲除Slc16a11不会造成显著的代谢缺陷；2）在小鼠肝脏中重构Slc16a11突变体会增加脂质的积累和诱导胰岛素抵抗；3）突变的SLC16A11通过上调Lipin1增加肝脏甘油三酯的水平。以上结论提示人群发现的2型糖尿病易感突变造成SLC16A11突变体是功能获得性突变，引起肝脏脂质积累增加。.科学意义：2017的一篇Cell文章同样对SLC16A11位点突变对2型糖尿病的影响进行了研究，他们通过人群相关联分析和细胞实验得到的结论是该位点的遗传突变主要导致了SLC16A11的功能缺失，继而导致肝脏脂肪积累。他们因此提议可潜在通过提高SLC16A11的表达水平进行2型糖尿病的治疗。我们在整体小鼠表型分析的研究基础上发现SLC16A11的功能缺失并不会导致糖尿病发生，而恰好相反，易感突变是SLC16A11的功能获得性突变，对之前研究的结论提出质疑。并发现在小鼠水平如果过表达SLC16A11，提高SLC16A11的表达水平会增加肝脏脂滴积累。因此我们的研究对正确理解这个位点的功能和致病机制以及发展相应的治疗措施提供了新的理论基础。