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Influence of glucose on pyruvate carboxylase expression in pancreatic islets.
- Source :
-
Archives of biochemistry and biophysics [Arch Biochem Biophys] 1995 May 10; Vol. 319 (1), pp. 128-32. - Publication Year :
- 1995
-
Abstract
- Pancreatic islets were cultured for 1 day in the presence of 1 to 20 mM glucose and islet proteins were separated on polyacrylamide gels and transferred to nitrocellulose. Pyruvate carboxylase and an unidentified biotin-containing protein were visualized with [125I]streptavidin followed by autoradiography. The amount of pyruvate carboxylase was proportional to the concentration of glucose. Estimates of the amount of the enzyme in islets were made by comparing the density of the islet pyruvate carboxylase band with a standard curve of various amounts of authentic pyruvate carboxylase. This indicated that the enzyme comprised 0.4% of total islet protein. Net synthesis of the enzyme was increased by cAMP and methyl succinate. A nuclear run-on assay showed that glucose caused increases in pyruvate carboxylase and pyruvate dehydrogenase E1 alpha subunit transcripts and decreases in branched chain ketoacid dehydrogenase E1 alpha transcripts in rat insulinoma (RINm5F) cells. Pancreatic islets cultured in the presence of 1 mM glucose for 1 day cannot respond to glucose with insulin release. Previous studies demonstrated that carbon flux into the citric acid cycle intermediates via both carboxylation and decarboxylation is decreased in glucose-incapacitated islets (M. J. MacDonald, 1993, Arch. Biochem. Biophys. 300, 205-214), 1993). The current results support the idea that carboxylation of glucose-derived pyruvate, as well as decarboxylation of pyruvate, is important for glucose-induced insulin secretion.
- Subjects :
- Animals
Biotin metabolism
Gene Expression Regulation, Enzymologic drug effects
In Vitro Techniques
Insulin metabolism
Insulin Secretion
Islets of Langerhans metabolism
Pyruvate Carboxylase biosynthesis
Pyruvate Carboxylase genetics
Rats
Glucose pharmacology
Islets of Langerhans drug effects
Islets of Langerhans enzymology
Pyruvate Carboxylase metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0003-9861
- Volume :
- 319
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Archives of biochemistry and biophysics
- Publication Type :
- Academic Journal
- Accession number :
- 7771776
- Full Text :
- https://doi.org/10.1006/abbi.1995.1274