Short-term regulation of insulin gene transcription by glucose.
Whereas short-term regulation of insulin biosynthesis at the level of translation is well accepted, glucose-dependent transcriptional control is still believed to be a long-term effect occurring after more than 2 hr of glucose stimulation. Because pancreatic beta cells are exposed to elevated glucose levels for minutes rather than hours after food uptake, we hypothesized the existence of a short-term transcriptional control. By studying the dynamics of newly synthesized (prepro)insulin RNA and by employing on-line monitoring of gene expression in single, insulin-producing cells, we were able to provide convincing evidence that insulin gene transcription indeed is affected by glucose within minutes. Exposure of insulinoma cells and isolated pancreatic islets to elevated glucose for only 15 min resulted in a 2- to 5-fold elevation in (prepro)insulin mRNA levels within 60-90 min. Similarly, insulin promoter-driven green fluorescent protein expression in single insulin-producing cells was significantly enhanced after transient glucose stimulation. Thus, short-term signaling, such as that involved in insulin secretion, also may regulate insulin gene transcription.
Leibiger
B
B
The Rolf Luft Center for Diabetes Research, Department of Molecular Medicine, Karolinska Institute, S-171 76 Stockholm, Sweden.
Moede
T
T
Schwarz
T
T
Brown
G R
GR
Köhler
M
M
Leibiger
I B
IB
Berggren
P O
PO
D000818:Animals; D001483:Base Sequence; D006224:Cricetinae; D017931:DNA Primers; D005786:Gene Expression Regulation / Q000187:drug effects*; D005947:Glucose / Q000494:pharmacology*; D049452:Green Fluorescent Proteins; D007328:Insulin / Q000494:pharmacology*; D008164:Luminescent Proteins / Q000235:genetics; D011384:Proinsulin / Q000235:genetics; D011498:Protein Precursors / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects*; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D007328:Insulin; D008164:Luminescent Proteins; D011498:Protein Precursors; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; C013737:preproinsulin; D011384:Proinsulin; D005947:Glucose