TY - JOUR
T1 - Glucose and forskolin regulate IAPP gene expression through different signal transduction pathways
AU - Ding, Wei Qun
AU - Holicky, Eileen
AU - Miller, Laurence J.
PY - 2001
Y1 - 2001
N2 - Molecular mechanisms for the regulation of islet amyloid polypeptide (IAPP) gene expression remain unclear. In the present study, we investigated the effects of glucose and forskolin on IAPP gene regulation in the INS-1 islet β-cell line. Both glucose and forskolin increased the level of expression of this gene, as measured by Northern blot analysis, and increased IAPP gene transcription in a time- and concentration-dependent manner, as demonstrated in a reporter gene assay. Although inhibition of protein kinase A activity with H-89 eliminated the effect of forskolin on this gene, the glucose effect was unaffected. This supported the predominant use of a protein kinase A-independent signaling pathway for glucose regulation of the IAPP gene. Electrophoretic mobility shift assay further indicated that glucose and forskolin regulated expression of this gene by targeting different elements of the promoter. Mutation of the cAMP regulatory element flanking the IAPP coding region resulted in the loss of most of the forskolin-stimulated IAPP gene promoter activity, whereas glucose-enhanced IAPP gene transcription was unaffected. These results demonstrate parallel and distinct regulatory pathways involved in glucose- and forskolin-induced IAPP gene expression in this model β-cell system.
AB - Molecular mechanisms for the regulation of islet amyloid polypeptide (IAPP) gene expression remain unclear. In the present study, we investigated the effects of glucose and forskolin on IAPP gene regulation in the INS-1 islet β-cell line. Both glucose and forskolin increased the level of expression of this gene, as measured by Northern blot analysis, and increased IAPP gene transcription in a time- and concentration-dependent manner, as demonstrated in a reporter gene assay. Although inhibition of protein kinase A activity with H-89 eliminated the effect of forskolin on this gene, the glucose effect was unaffected. This supported the predominant use of a protein kinase A-independent signaling pathway for glucose regulation of the IAPP gene. Electrophoretic mobility shift assay further indicated that glucose and forskolin regulated expression of this gene by targeting different elements of the promoter. Mutation of the cAMP regulatory element flanking the IAPP coding region resulted in the loss of most of the forskolin-stimulated IAPP gene promoter activity, whereas glucose-enhanced IAPP gene transcription was unaffected. These results demonstrate parallel and distinct regulatory pathways involved in glucose- and forskolin-induced IAPP gene expression in this model β-cell system.
KW - Cyclic adenosine 3,5-monophosphate
KW - Islet amyloid polypeptide
KW - Protein kinase A
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U2 - 10.1152/ajpendo.2001.281.5.e938
DO - 10.1152/ajpendo.2001.281.5.e938
M3 - Article
C2 - 11595649
AN - SCOPUS:0035195537
SN - 0193-1849
VL - 281
SP - E938-E945
JO - American Journal of Physiology - Endocrinology and Metabolism
JF - American Journal of Physiology - Endocrinology and Metabolism
IS - 5 44-5
ER -