Detailed molecular analysis of the induction of the L-PK gene by glucose

• Published in: Biochemical and biophysical research communications Vol. 372; no. 1; pp. 131 - 136
• Main Authors: Eckert, David T., Zhang, Pili, Collier, J. Jason, O’Doherty, Robert M., Scott, Donald K.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 18-07-2008
• Subjects: 60 APPLIED LIFE SCIENCES; Acetylation; Animals; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors - metabolism; Cell Line, Tumor; CHROMATIN; Chromatin immunoprecipitation; Chromones - pharmacology; Gene Expression Regulation; Gene promoter; GENES; GLUCOSE; Glucose - metabolism; Glucose - pharmacology; Glucose signaling; Hepatocyte Nuclear Factor 4 - metabolism; Hepatocytes; HISTONES; Histones - metabolism; INSULIN; Insulin-independent; L-type pyruvate kinase; LIVER; Liver - enzymology; LIVER CELLS; LY294002; LY303511; Morpholines - pharmacology; Phosphatidylinositol 3-Kinases - antagonists & inhibitors; Phosphatidylinositol 3-Kinases - metabolism; PHOSPHORYLATION; Piperazines - pharmacology; POLYMERASE CHAIN REACTION; Promoter Regions, Genetic; PROMOTERS; Pyruvate Kinase - genetics; Rats; RNA Polymerase II - metabolism; RNA POLYMERASES; RNA Stability; RNA, Messenger - metabolism; Serine - metabolism; TRANSCRIPTION; Transcription Initiation Site; Transcription, Genetic - drug effects; Chromatin immunoprecipitation; LY294002; Hepatocytes; L-type pyruvate kinase; Glucose signaling; LY303511; Insulin-independent; Gene promoter
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2008.05.002

Glucose has powerful effects on gene expression and participates in the fasted-to-fed transition of the liver. However, the molecular mechanism of glucose-regulated gene expression has not been completely described. In the present study, we performed a detailed analysis of the molecular events of the insulin-independent glucose response of the liver-type pyruvate kinase (L-PK) gene. L-PK mRNA was increased by glucose at the transcriptional level as determined by real-time RT-PCR, mRNA stability measurements, and nuclear run-on assays. LY294002 and LY303511 inhibited the glucose response of the L-PK gene at the transcriptional level. Histones H3 and H4 associated with the L-PK gene promoter were hyperacetylated and HNF4α was constitutively bound in low and high glucose. Treatment with 20
mM glucose increased recruitment of ChREBP, additional HNF4α, and RNA polymerase II. Glucose-stimulated the phosphorylation of the C-terminal domain of RNA polymerase II, with increased Ser5 phosphorylation near the transcription start site and increased Ser2 phosphorylation near the termination signal. LY294002 and LY303511 blocked the recruitment of RNA polymerase II to the L-PK gene, reducing the rate of transcription. The results of these studies demonstrate fundamental details of the molecular mechanism of glucose activated gene expression.