Molecular Medicine of Clinical Implication of Obese Gene Product

（目的）研究瘦素和解偶联蛋白3 （uncoupling protein 3, UCP3）的病理生理意义。（方法）对17例BMI大于30且有肥胖家族史的日本肥胖患者进行直接测序，确定瘦素受体cDNA所有外显子的结构。通过SSCP和PCR-RFLP分析，测定了46例BMI为bbbb30的日本人和64例BMI < 25的日本人瘦素受体基因多态性的等位基因频率。利用与小鼠UCP2 cDNA的同源性，我们从大鼠骨骼肌中克隆了UCP3 cDNA。我们检测了高脂饮食大鼠中UCP3基因的表达。我们研究了吡格列酮治疗Wistar脂肪大鼠UCP3基因的表达。我们检测了大鼠附睾脂肪原代成熟脂肪细胞中UCP3基因的表达。（结果）在日本病态肥胖人群中鉴定出7个瘦素受体基因多态性。在所有多态性中，非肥胖和病态肥胖受试者的等位基因频率无显著差异。在大鼠骨骼肌中克隆了UCP3 cDNA。高脂饲料大鼠UCP3基因表达升高2倍。我们观察到UCP3基因表达在附睾脂肪中显著增加了2.1倍，在腹膜后脂肪中增加了2.0倍，在棕色脂肪中增加了1.6倍。我们观察到吡格列酮从10^<-5>M浓度开始显著增加大鼠原代白色脂肪细胞中UCP3基因的表达。（讨论）日本大多数肥胖者的肥胖不能用瘦素受体基因多态性来解释。我们从大鼠骨骼肌中克隆了UCP3 cDNA。我们证明了高脂肪饲料喂养和噻唑烷增加了UCP3基因的表达。

(Purpose) We examined pathophysiological significance of leptin, and uncoupling protein 3 (UCP3) which appears to be downstream of leptin.(Methods) We determined the structure of all exons of leptin receptor cDNA by direct sequencing in 17 Japanese obese subjects whose BMI is higher than 30 and who have family history of obesity. We determined allele frequency of polymorphisms of leptin receptor gene in 46 Japanese subjects with BMI > 30 and 64 subjects with BMI < 25 by SSCP and PCR-RFLP analyses. Using homology to mouse UCP2 cDNA, we cloned UCP3 cDNA from rat skeletal muscle. We examined UCP3 gene expression in rats fed high-fat diet. We investigated UCP3 gene expression in Wistar fatty rats treated with pioglitazone. We examined the UCP3 gene expression in primary mature adipocytes culture from rat epididymal fat.(Results) We identified 7 polymorphisms in leptin receptor gene in Japanese morbidly obese subjects. No significant difference of allele frequency was noted between nonobese and morbidly obese subjects in all polymorphisms. UCP3 cDNA was cloned in rat skeletal muscle. Two-fold elevation of UCP3 gene expression was observed in rats fed high-fat diet. We observed significant increase of UCP3 gene expression by 2.1-fold in the epididymal fat, by 2.0-fold in the retroperitoneal fat, and by 1.6-fold in the brown fat. We observed significant increase of UCP3 gene expression by pioglitazone from the concentration of 10^<-5>M in rat primary white adipocyte culture.(Discussion) Obesity in most of Japanese morbidy obese subjects can not be explained by leptin receptor gene polymorphisms. We cloned UCP3 cDNA from rat skeletal muscle. We demonstrated the increase of the UCP3 gene expression by high-fat diet feeding and by thiazolidines.