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Biochim Biophys Acta. 2013 Sep;1829(9):905-15. doi: 10.1016/j.bbagrm.2013.04.009. Epub 2013 Apr 28.

Starvation actively inhibits splicing of glucose-6-phosphate dehydrogenase mRNA via a bifunctional ESE/ESS element bound by hnRNP K.

Author information

1
Department of Biochemistry, West Virginia University, Morgantown, WV 26506, USA.

Abstract

Regulated expression of glucose-6-phosphate dehydrogenase (G6PD) is due to changes in the rate of pre-mRNA splicing and not changes in its transcription. Starvation alters pre-mRNA splicing by decreasing the rate of intron removal, leading to intron retention and a decrease in the accumulation of mature mRNA. A regulatory element within exon 12 of G6PD pre-mRNA controls splicing efficiency. Starvation caused an increase in the expression of heterogeneous nuclear ribonucleoprotein (hnRNP) K protein and this increase coincided with the increase in the binding of hnRNP K to the regulatory element and a decrease in the expression of G6PD mRNA. HnRNP K bound to two C-rich motifs forming an ESS within exon 12. Overexpression of hnRNP K decreased the splicing and expression of G6PD mRNA, while siRNA-mediated depletion of hnRNP K caused an increase in the splicing and expression of G6PD mRNA. Binding of hnRNP K to the regulatory element was enhanced in vivo by starvation coinciding with a decrease in G6PD mRNA. HnRNP K binding to the C-rich motifs blocked binding of serine-arginine rich, splicing factor 3 (SRSF3), a splicing enhancer. Thus hnRNP K is a nutrient regulated splicing factor responsible for the inhibition of the splicing of G6PD during starvation.

KEYWORDS:

Liver; Nutrient regulation; SRSF3; hnRNP K; mRNA splicing

PMID:
23631859
PMCID:
PMC3714377
DOI:
10.1016/j.bbagrm.2013.04.009
[Indexed for MEDLINE]
Free PMC Article

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