Molecular Medicine of Clinical Implication of Obese Gene Product

（目的）探讨瘦素及其下游的解偶联蛋白3（UCP 3）的病理生理学意义。（方法）采用直接测序法对17名日本肥胖者（BMI> 30，有肥胖家族史）的瘦素受体cDNA的所有外显子进行结构测定。我们采用SSCP和PCR-RFLP分析方法测定了46名日本人BMI > 30和64名日本人BMI < 25的瘦素受体基因多态性等位基因频率。利用与小鼠UCP 2 cDNA的同源性，我们从大鼠骨骼肌中克隆了UCP 3 cDNA。我们检测了高脂饮食大鼠UCP 3基因的表达。我们研究了吡格列酮治疗的Wistar肥胖大鼠中UCP 3基因的表达。我们检测了UCP 3基因在大鼠附睾脂肪原代成熟脂肪细胞培养中的表达。（结果）我们在日本病态肥胖受试者中发现了瘦素受体基因的7个多态性。在所有多态性中，非肥胖和病态肥胖受试者之间的等位基因频率没有显着差异。在大鼠骨骼肌中克隆了UCP 3 cDNA。在喂食高脂饮食的大鼠中观察到UCP 3基因表达的两倍升高。我们观察到UCP 3基因表达在附睾脂肪中显著增加2.1倍，在腹膜后脂肪中增加2.0倍，在棕色脂肪中增加1.6倍。在大鼠原代白色脂肪细胞培养物中，我们观察到吡格列酮从10 μ M浓度开始显著增加UCP 3基因表达<-5>。（讨论）日本病态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UCP 3 cDNA。我们证明了UCP 3基因表达的增加，高脂肪饮食喂养和噻唑烷。

(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.