MOLECULAR-CLONING OF A GROUP OF MOUSE PANCREATIC-ISLET BETA-CELL-RELATED GENES BY RANDOM CDNA SEQUENCING

To understand the molecular basis of glucose concentration-responsive insulin synthesis and secretion from pancreatic islet beta cells, a gr oup of pancreatic islet beta-cell-related cDNAs was cloned. A pair of cDNA libraries was constructed from a mouse pancreatic islet beta-cell line of MIN6, which was cultured in either high glucose or low glucos e media. By applying a random cDNA sequencing approach, 503 and 395 in dependent species were obtained from a total of 1,011 and 762 clones i n the high glucose and low glucose library, respectively. The unknown genes comprised the majority of about 70 % independent clones in both libraries. In Northern blot analysis, 311 (69.4 %) of 448 independent clones showed positive signals within 72 h of autoradiographic exposur e. Surprisingly, 150 (48.2 %) out of 311 positive clones showed positi ve signals to MING cells, but not to NIH/3T3 fibroblasts. The expressi on level of three unknown clones were glucose-concentration dependent. Combination of a random cDNA sequencing approach and Northern blot an alysis is useful to obtain a large number of novel genes and islet bet a-cell-related genes.