Functional analysis of DNA-elements involved in transcriptional control of the human glucose transporter 2 (GLUT 2) gene in the insulin-producing cell line βTC-3
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The uptake of glucose into pancreatic beta cells as a ‘non-rate-limiting-step’ is guaranteed by the expression and action of the high-Km glucose transporter 2 (GLUT 2). This transporter is not saturated by physiological plasma glucose levels and hence functions as a “glucose sensor/glucoreceptor”. Here we describe DNA-elements of the human GLUT 2 gene promoter which contribute to transcriptional control in the insulin-producing cell line βTC-3. Nested 5′-as well as 3′-deletions of a DNA-fragment containing up to 1245 bp of the 5′-flanking region and up to 308 bp of the first exon of the human GLUT 2 gene were investigated for their ability to control the expression of a CAT reporter gene in βTC-3 cells. For tissue-specific transcriptional control 5′-deletional analysis revealed that the region −220/+309 was sufficient. Truncation from the 3′-end from nucleotide +308 to +204 led to a threefold drop in CAT expression.In vitro DNase I footprinting analysis was performed to delineatecis-elements within the region −220/+1. Five specifically protected areas could be defined. [Diabetologia (1995) 38: 112–115]
Key wordsGene expression regulation insulinoma glucose transporter transcription promoter
- GLUT 2
polymearase chain reaction
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