| First Author | Li T | Year | 2008 |
| Journal | Gastroenterology | Volume | 134 |
| Issue | 7 | Pages | 1994-2003 |
| PubMed ID | 18440316 | Mgi Jnum | J:136663 |
| Mgi Id | MGI:3796762 | Doi | 10.1053/j.gastro.2008.02.076 |
| Citation | Li T, et al. (2008) Sp1 is required for glucose-induced transcriptional regulation of mouse vesicular glutamate transporter 2 gene. Gastroenterology 134(7):1994-2003 |
| abstractText | BACKGROUND & AIMS: Vesicular glutamate transporter (VGLUT) has been reported to be involved in glucose-induced insulin secretion. It has been shown that glucose stimulates the expression of VGLUT isoform 2 (VGLUT2) in beta cells via transcriptional mechanism. In this study, we identified the mouse VGLUT2 (mVGLUT2) promoter and characterized the transcriptional mechanism of glucose-stimulated mVGLUT2 expression in beta-cells. METHODS: A promoter region of mVGLUT2 was cloned by genomic polymerase chain reaction. The mechanism of Sp1 in glucose-induced transactivation of mVGLUT2 was investigated by luciferase assay, electrophoretic mobility shift assay, chromatin immunoprecipitation assay, and Western blot analysis. RESULTS: A promoter containing 2133 base pairs of upstream sequence of the 5'-flanking region of mVGLUT2 complementary DNA was cloned. Transient transfection of various 5'-end deletion constructs of the mVGLUT2 promoter/luciferase reporter indicated that the region between -96 to +68 base pair contains the basal promoter for mVGLUT2. Mutational analysis and electromobility shift assay showed an important role for the transcription factor Sp1 in both basal and glucose-induced mVGLUT2 transcription. The interaction between Sp1 and mVGLUT2 was confirmed by chromatin immunoprecipitation assays. Glucose stimulates the phosphorylation of Sp1 via mitogen-activated protein kinase P38 and P44/42. This leads to increased binding activity of Sp1 to the mVGLUT2 promoter and results in activation of the gene. CONCLUSIONS: We cloned the mouse VGLUT2 promoter and showed a novel molecular mechanism of glucose-induced mVGLUT2 transcription. |
