Title | Dietary polyunsaturated fatty acids interfere with the insulin/glucose activation of L-type pyruvate kinase gene transcription. |
Publication Type | Journal Article |
Year of Publication | 1994 |
Authors | Liimatta, M, Towle, HC, Clarke, S, Jump, DB |
Journal | Mol Endocrinol |
Volume | 8 |
Issue | 9 |
Pagination | 1147-53 |
Date Published | 1994 Sep |
ISSN | 0888-8809 |
Keywords | Animals, Arachidonic Acid, Base Sequence, Cells, Cultured, Depression, Chemical, Dietary Fats, DNA-Binding Proteins, Eicosapentaenoic Acid, Enzyme Induction, Fatty Acids, Unsaturated, Fish Oils, Glucose, Glycolysis, Hepatocyte Nuclear Factor 4, Insulin, Liver, Male, Molecular Sequence Data, Mutagenesis, Site-Directed, Oleic Acid, Oleic Acids, Phosphoproteins, Pyruvate Kinase, Rats, Rats, Sprague-Dawley, Recombinant Fusion Proteins, RNA, Messenger, Transcription Factors, Transcription, Genetic |
Abstract |
L-type pyruvate kinase (L-PK) is a key glycolytic enzyme regulating the flux of metabolites through the pyruvate-phosphoenolpyruvate cycle (1). The regulation of L-PK is complex involving both hormones and nutrients. We have found that feeding rats diets containing polyunsaturated fatty acids (PUFA) significantly inhibits hepatic pyruvate kinase enzyme activity (> 60%) and suppresses mRNAPK abundance (> 70%). Studies with primary hepatocytes indicate that PUFA act directly on hepatocytes. Specifically, arachidonic (20:4, omega 6) and eicosapentaenoic (20:5, omega 3) acid suppressed both mRNAPK llevels and the activity of a transfected PKCAT (-4300/+12) fusion gene by > 70%. This is due to an inhibition of the insulin/glucose-mediated transactivation of L-PKCAT. Deletion analysis localized PUFA-regulated cis-acting elements to a region within the L-PK proximal promoter, i.e. between -197 and -96 base pairs. This region binds two transcription factors involved in the hormone/nutrient regulation of L-PK gene transcription, i.e. a major late transcription factor-like factor and HNF-4. Linker scanning mutation analysis localized the PUFA-regulated cis-acting elements to the vicinity of the HNF-4 binding site. Thus, PUFA-regulated factors abrogate the insulin/glucose activation of L-PK gene transcription by targeting the HNF-4 elements. These studies suggest that PUFA may have significant effects on hepatic carbohydrate metabolism by inhibiting the L-PK side of the pyruvate-phosphoenolpyruvate cycle. |
DOI | 10.1210/mend.8.9.7838147 |
Alternate Journal | Mol. Endocrinol. |
PubMed ID | 7838147 |
Grant List | R01 DK043220 / DK / NIDDK NIH HHS / United States DK-26919 / DK / NIDDK NIH HHS / United States DK-43220 / DK / NIDDK NIH HHS / United States |