Genes involved in insulin secretion and improvement of detection method for gene mutations in diabetic patients

为了研究线粒体基因tRNALeu（UUR）突变引起的糖尿病的患病率和临床特征，我们对440例母亲患有糖尿病的糖尿病患者进行了线粒体基因核苷酸对（np）3250、3256、3260、3271和3291的突变以及3243处的A到G转换的筛查。本研究采用~（32）P标记的序列特异性寡核苷酸（SSO）为探针的斑点杂交法。虽然没有发现糖尿病患者在np 3250、3256、3260或3291处有点突变，但鉴定出1例在np 3271处携带T到C的转变，7例在3243处携带A到G的转变。3271突变的患者是一名39岁的男性，仅通过饮食治疗就能很好地控制血糖，没有听力障碍，也没有提示线粒体肌病、脑病、乳酸酸中毒和卒中样发作（MELAS）的症状。总之，在糖尿病患者中，3271突变的发生率约为3243突变的14%，而其他tRNALeu（UUR）突变在母系遗传的糖尿病中更为罕见。我们还从胰腺β细胞中克隆了与葡萄糖诱导的胰岛素分泌相关的基因hGIRK 2和mGPDH，并分析了日本糖尿病患者中这些基因的突变。

To investigate the prevalence and clinical characteristics of diabetes mellitus caused by mitochondrial gene mutations in the tRNALeu (UUR), we screened 440 diabetic patients with diabetic mothers for mitochondrial gene mutations at nucleotide pair (np) 3250,3256,3260,3271 and 3291 in addition to an A to G transition at up 3243. The dot-blot hybridization method using 32P-labeled sequence-specific oligonucleotides (SSO) as probes was employed in this study. While no diabetic patients having a point-mutation at np 3250,3256,3260 or 3291 were found, one carrying a T to C transition at np 3271 and seven carrying an A to G transition at 3243 were identified. The patient with the 3271 mutation, a 39-year-old male, had excellent glycemic control with diet therapy alone and had neither hearing impairment nor symptoms suggesting mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS). In summary, among diabetic patients, the prevalence of the 3271 mutation was about 14% that of the 3243 mutation, while other mutations in the tRNALeu (UUR) are even more rare in maternally transmitted diabetes.We have also cloned the gene involved in glucose-induced insulin secretion from pancreatic beta cells, hGIRK2 and mGPDH,and analyzed the mutations of these genes in Japanese diabetic patients.