Abstract
Nutrient regulation of glucose-6-phosphate dehydrogenase (G6PD) expression occurs through changes in the rate of splicing of G6PD pre-mRNA. This posttranscriptional mechanism accounts for the 12- to 15-fold increase in G6PD expression in livers of mice that were starved and then refed a high-carbohydrate diet. Regulation of G6PD pre-mRNA splicing requires a cis-acting element in exon 12 of the pre-mRNA. Using RNA probes to exon 12 and nuclear extracts from livers of mice that were starved or refed, proteins of 60 kDa and 37 kDa were detected bound to nucleotides 65-79 of exon 12 and this binding was decreased by 50% with nuclear extracts from refed mice. The proteins were identified as hnRNPs K, L, and A2/B1 by LC-MS/MS. The decrease in binding of these proteins to exon 12 during refeeding was not accompanied by a decrease in the total amount of these proteins in total nuclear extract. HnRNPs K, L and A2/B1 have known roles in the regulation of mRNA splicing. The decrease in binding of these proteins during treatments that increase G6PD expression is consistent with a role for these proteins in the inhibition of G6PD mRNA splicing.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Blotting, Western
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Chromatography, Liquid
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Dietary Carbohydrates / administration & dosage
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Dietary Carbohydrates / metabolism
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Electrophoresis, Gel, Two-Dimensional
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Exons / genetics
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Glucosephosphate Dehydrogenase / genetics
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Heterogeneous-Nuclear Ribonucleoprotein Group A-B / chemistry
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Heterogeneous-Nuclear Ribonucleoprotein Group A-B / metabolism*
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Heterogeneous-Nuclear Ribonucleoprotein K / chemistry
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Heterogeneous-Nuclear Ribonucleoprotein K / metabolism*
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Heterogeneous-Nuclear Ribonucleoprotein L / chemistry
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Heterogeneous-Nuclear Ribonucleoprotein L / metabolism*
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Male
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Mass Spectrometry
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Mice
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Mice, Inbred C57BL
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Molecular Weight
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Oligoribonucleotides / genetics
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Oligoribonucleotides / metabolism
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Protein Binding
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RNA Precursors / genetics
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RNA Precursors / metabolism*
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RNA Processing, Post-Transcriptional
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RNA Splicing*
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RNA-Binding Proteins / chemistry
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RNA-Binding Proteins / metabolism
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Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
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Starvation
Substances
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Dietary Carbohydrates
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Heterogeneous-Nuclear Ribonucleoprotein Group A-B
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Heterogeneous-Nuclear Ribonucleoprotein K
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Heterogeneous-Nuclear Ribonucleoprotein L
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Oligoribonucleotides
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RNA Precursors
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RNA-Binding Proteins
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hnRNP A2
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Glucosephosphate Dehydrogenase