The mechanism by which glucose stimulates insulin gene expression has been investigated by studying the binding of nuclear proteins to a putative glucose-sensitive element (GSE) in the rat insulin-I gene promoter. Gel retardation assays showed that a specific binding activity was present in four different beta-cell lines. The binding activity was increased by glucose only in those beta-cell lines which were shown to retain glucose-regulated insulin gene transcription. However, a similar binding activity was also shown to be present in an alpha-cell line. The protein factor binding to the GSE was estimated to have a molecular weight of 27kD. This protein may play a pivotal role in glucose-regulated transcription of the insulin gene.
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