LIPOPROTEIN LIPASE DEFICIENCY: GENETICS AND BIOCHEMISTRY

脂蛋白脂酶(LPL)是甘油三酯代谢的关键酶。 富含高密度脂蛋白。有缺陷的功能酶是 一种罕见的常染色体隐性遗传综合征家族性LPL的诊断特征 缺乏症。我们已经确定了该基因的几个突变 LPL缺乏的受试者，并显示LPL的杂合态 缺乏(LPLn)导致家族性高甘油三酯血症(HTG) 血统很大。 我们打算进行一项系统的遗传和生化研究 LPL在经典的虚弱状态以及在各种临床上 HTG的病理生理学意义不是 了解，包括冠心病，高血压， 糖尿病、妊娠高血压综合征或糖尿病，以及急性 胰腺炎，通过多种来源在两个盐地招募受试者 湖城和旧金山。 为达致这些科学目标，我们建议： (1)家族性LPL缺乏症患者LPL基因突变的鉴定 通过对LPL外显子和内含子-外显子边界进行测序； (2)在一大系列HTG受试者中寻找LPL突变 通过斑点杂交筛选已知突变的各种临床情况 杂交和通过直接检测未知突变 核苷酸变体(单链构象多态或化学 错配检测)和DNA测序； (3)体外实验证实这些突变的功能意义。 在哺乳动物细胞中的诱变和表达； (4)通过测试确定每个突变影响的功能结构域 颗粒和可溶性底物的催化活性，亲和力 脂质、载脂蛋白C-II和肝素，以及与二聚体的自结合； (5)在已发生取代的残基上进行体外表达 确定以研究结构域的结构-功能关系 牵涉其中。

Lipoprotein lipase (LPL) is a key enzyme in the metabolism of triglyceride- rich and high density lipoproteins. Defective functional enzyme is the diagnostic feature of a rare autosomal recessive syndrome, familial LPL deficiency. We have already identified several mutations of the gene in LPL deficient subjects and shown that the heterozygous state for LPL deficiency (LPLn) accounted for familial hypertriglyceridemia (HTG) in a large pedigree. We intend to pursue a systematic genetic and biochemical investigation of LPL in classical deficiency states as well as in a variety of clinical contexts where the pathophysiological significance of HTG is not understood, including coronary heart disease, essential hypertension, diabetes, pregnancy-induced hypertension or diabetes, and acute pancreatitis, recruiting subjects through multiple sources in both Salt Lake City and San Francisco. To achieve these scientific objectives, we propose to: (1) identify mutations of the LPL gene in familial LPL deficiency patients by sequencing LPL exons and intron-exon boundaries; (2) search for mutations of LPL in a large series of HTG subjects in various clinical contexts, screening for known mutations by dot-blot hybridization and for unidentified mutations by direct detection of nucleotide variants (single strand conformation polymorphism or chemical mismatch detection) and DNA sequencing; (3) confirm the functional significance of these mutations by in vitro mutagenesis and expression in mammalian cells; (4) identify the functional domain affected by each mutation by testing catalytic activity with particulate and soluble substrates, affinity for lipid, apolipoprotein C-II and heparin, and self-association to a dimer; (5) perform in vitro expression at residues where substitutions have been identified to investigate structure-function relationships of the domains involved.