title: Elevated copper remodels hepatic RNA processing machinery in the mouse model of Wilson's disease.
abstract: Copper is essential to mammalian physiology, and its homeostasis is tightly regulated. In humans, genetic defects in copper excretion result in copper overload and Wilson's disease (WD). Previous studies on the mouse model for WD (Atp7b(-)(/-)) revealed copper accumulation in hepatic nuclei and specific changes in mRNA profile prior to the onset of pathology. To find a molecular link between nuclear copper elevation and changes in hepatic transcriptome, we utilized quantitative ionomic and proteomic approaches. X-ray fluorescence and inductively coupled plasma mass spectrometry analysis indicate that copper in the Atp7b(-/-) nucleus, while highly elevated, does not markedly alter nuclear ion content. Widespread protein oxidation is also not observed, although the glutathione reductase SelH is upregulated, likely to maintain redox balance. We further demonstrate that accumulating copper affects the abundance and/or modification of a distinct subset of nuclear proteins. These proteins populate pathways that are most significantly associated with RNA processing. An alteration in splicing pattern was observed for hnRNP A2/B1, itself the RNA shuttling factor and spliceosome component. Analysis of hnRNP A2/B1 mRNA and protein revealed an increased retention of exon 2 and a selective 2-fold upregulation of a corresponding protein splice variant. Mass spectrometry measurements suggest that the nucleocytoplasmic distribution of RNA binding proteins, including hnRNP A2/B1, is altered in the Atp7b(-/-) liver. We conclude that remodeling of the RNA processing machinery is an important component of cell response to elevated copper that may guide pathology development in the early stages of WD.
authors.affiliation: University of Alaska Anchorage, Anchorage, AK 99508, USA.
authors.forename: Jason L
authors.initials: JL
authors.lastname: Burkhead
authors.forename: Martina
authors.initials: M
authors.lastname: Ralle
authors.forename: Phillip
authors.initials: P
authors.lastname: Wilmarth
authors.forename: Larry
authors.initials: L
authors.lastname: David
authors.forename: Svetlana
authors.initials: S
authors.lastname: Lutsenko
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics; D000818:Animals; D027682:Cation Transport Proteins / Q000235:genetics; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D003300:Copper / Q000032:analysis / Q000378:metabolism*; D000073840:Copper-Transporting ATPases; D004195:Disease Models, Animal; D005091:Exons; D005260:Female; D020869:Gene Expression Profiling; D005980:Glutathione Reductase / Q000032:analysis / Q000378:metabolism; D006527:Hepatolenticular Degeneration / Q000378:metabolism*; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000032:analysis / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D051379:Mice; D009687:Nuclear Proteins / Q000032:analysis / Q000378:metabolism; D020033:Protein Isoforms / Q000032:analysis / Q000378:metabolism; D040901:Proteomics; D012326:RNA Splicing; D017381:Spliceosomes / Q000737:chemistry / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C486201:Atp7a protein, mouse; D027682:Cation Transport Proteins; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D009687:Nuclear Proteins; D020033:Protein Isoforms; C439768:hnRNP A2; D003300:Copper; D005980:Glutathione Reductase; D000251:Adenosine Triphosphatases; D000073840:Copper-Transporting ATPases