A mutation in the promoter of human GLUT2 is associated with diabetes and affects the transcriptional activity in vitro

In oider to understand the decreased expression of pancreatic rell/li\er type glucose transporter gene in noninsulin dependent diabetes molbtus( MDOM}. we have sequenced tho promoter region of human LI' 12 gone to idontiiy the possible mutations which may be critical to its expression. I<> this end. genomic UNA from peripheral lymphocytes of control subjects. NIDDM. and insulin dependent diabetes mellitus(II)l)M) patients{each group consisted of '20 peoples) were fractionated and the promoter regions(-29 I/ -(-300) of GM'T2 were amplified using poiyrnerase chain reaction. 1 he sequencing of ihe region revealed thai only one person in control group showed A >Ci mutation at 4-1. In MDDM and IDDM patients, the frequencies of A >(J mutalion were 60% and 'M%, respectively. Interestingly, all the mutations existed in t he form of hétérozygotes. To confirm the possible effect of I lie mutation un the promoter activity. ("AI activity was measured. The CAT acli\ity of mutated promoter v.as about 50% ofthat of wild type promoter. This result suggests that the mutation a! -14 region may affect the GHT2 gene transcription in diabetic patients. However, the reason why the mutation wa, observed in iiO'X of the IDDM patients remains to be clarified. Because the 44 region falls within tho CI' motif( Lo.ibigor and Leibiger. 1995). the promoter region con taining mutated base was subcloned into pCATii eukaryotic expression vector tor piomoter .u tiviiy.