| Research Abstract |
In order to understand the pathogenesis of type 2 diabetes, it is important to understand the expression profile of the mRNAs in pancreatic islets. In the present study, we have identified a large number of non-redundant cDNAs, considerably increasing the catalog of genes expressed in human endocrine pancreas. The partial sequences (expressed sequence tags, ESTs) of 〜22,000 clones randomly selected from a cDNA library of human pancreatic islet tumors were determined and compared with those deposited in the public databases. Clustering analysis of 21,267 ESTs obtained by 3'-end sequencing of cDNA inserts generated 6,157 non-redundant sequences comprising 2,323 groups and 3,834 singletons. Nucleotide and peptide database searches using the 3'- and 5'-ESTs, respectively, show that 3,103 and 58 of these ESTs represent known human sequences or human homologs of genes identified in other species and new members of structurally related families, respectively. The sequences also were compared with the public EST databases (dbEST and EPConDB) including ESTs from pancreatic islet, insulinoma, and fetal pancreas. As the result, 3,384 genes, including 587 unique to the islets, are newly found to be expressed in human pancreatic islets. These sequences were classified on the basis of the putative protein functions encoded, and were assigned to the respective chromosome by genome database analysis. In addition, multiple intron or intragenic SNPs (iSNPs) were identified in each of the genes unique to pancreatic islets. The larger collection of human pancreatic islet-related ESTs and iSNP genetic markers should provide a better genome source for molecular studies of tissue-specific functions of endocrine pancreas as well as for genetic studies of diabetes mellitus.
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