Positional cloning of carnitine transporter gene and its contribution on hypoglycemia.

青少年Visceral Steatosis （JVS）鼠标，我们在1991年报道的，作为一种初级肉碱缺陷的动物模型提供服务。因为这个鼠标从严重的低血糖症中获益，我们分析了因果关系和机制：结果的摘要如下;1.测定肉碱运输活动我们已经使用纤维块从正常、异质和均匀的JVS老鼠进行动力学分析，并找到了高亲和力的肉碱运输机，当显示Na-D1+ Y-D1依赖性时，在均匀的JVS老鼠中被破坏。Moreover，一种基因依赖于肉碱运输活动的降解在不同的JVS Mice.2中发现。对候选基因的分析，即人类OCTN 2基因编码一种依赖于钠的肉碱仙人掌是孤立的，我们孤立了小鼠的OCTN 2基因，并筛选出它在JVS小鼠中的突变。DNA sequencing analysis disclosed a missense mutation from CTG （Leu） to CGG （Arg） at codon352 located within the sixth transmembrane domain of octn2。这一氨基酸的替换可能导致蛋白质的修饰性变化，导致基因产品的功能失调。对Hypoglycemia的分析表明，JVS鼠标在广告库喂养时的葡萄糖水平低于正常控制。在延长的停滞之后，JVS鼠标的葡萄糖水平在60小时内被显著降低，与正常控制进行比较。胰岛素水平在JVS和正常控制鼠标之间没有改变。幽门螺杆菌和乳酸菌的水平已经退化。这一决定是因为催眠术的原因而产生的。

Juvenile Visceral Steatosis (JVS) mouse, which we reported in 1991, serves as an animal model of primary carnitine deficiency. Because this mouse is suffered from severe hypoglycemia, we analyzed the cause and mechanism The summary of the results is as follows ;1. Assay of carnitine transport activityWe have conducted a kinetic analysis using fibroblasts derived from normal, heterozygous, and homozygous JVS mice and found that the high-affinity carnitine transporter, which shows NaィイD1+ィエD1 dependency, is defective in homozygous JVS mice. Moreover, a gene dose-dependent decrease of carnitine transport activity was found in heterozygous JVS mice.2. Analysis of candidate geneAs a human OCTN2 gene encoding a sodium-dependent carnitine cotranspoter was isolated, we isolated the mouse octn2 gene and screened for its mutation in the JVS mouse. DNA sequencing analysis disclosed a missense mutation from CTG (Leu) to CGG (Arg) at codon 352 located within the sixth transmembrane domain of octn2. This amino acid replacement possibly causes the conformational change of the protein that leads to dysfunction of the gene product.3. Analysis of hypoglycemiaThe glucose level of JVS mouse at ad lib feeding was lower than that of normal control. After the prolonged starvation, the glucose level of JVS mouse was significantly decreased at 60 hours in comparison with normal control. The insulin level was not changed between JVS and normal control mouse. The levels of pyruvate and lactate were decreased. This decreased was thought as a cause of hypoglycemia.