title: Sarco(endo)plasmic reticulum ATPase is a molecular partner of Wolfram syndrome 1 protein, which negatively regulates its expression.
abstract: Wolfram syndrome is an autosomal recessive disorder characterized by neurodegeneration and diabetes mellitus. The gene responsible for the syndrome (WFS1) encodes an endoplasmic reticulum (ER)-resident transmembrane protein that is involved in the regulation of the unfolded protein response (UPR), intracellular ion homeostasis, cyclic adenosine monophosphate production and regulation of insulin biosynthesis and secretion. In this study, single cell Ca(2+) imaging with fura-2 and direct measurements of free cytosolic ATP concentration ([ATP]CYT) with adenovirally expressed luciferase confirmed a reduced and delayed rise in cytosolic free Ca(2+) concentration ([Ca(2+)]CYT), and additionally, diminished [ATP]CYT rises in response to elevated glucose concentrations in WFS1-depleted MIN6 cells. We also observed that sarco(endo)plasmic reticulum ATPase (SERCA) expression was elevated in several WFS1-depleted cell models and primary islets. We demonstrated a novel interaction between WFS1 and SERCA by co-immunoprecipitation in Cos7 cells and with endogenous proteins in human neuroblastoma cells. This interaction was reduced when cells were treated with the ER stress inducer dithiothreitol. Treatment of WFS1-depleted neuroblastoma cells with the proteasome inhibitor MG132 resulted in reduced accumulation of SERCA levels compared with wild-type cells. Together these results reveal a role for WFS1 in the negative regulation of SERCA and provide further insights into the function of WFS1 in calcium homeostasis.
authors.affiliation: Department of Medical and Molecular Genetics.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Zatyka
authors.affiliation: Department of Cell Biology, Division of Medicine, Faculty of Medicine, Imperial Centre for Translation and Experimental Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Da Silva Xavier
authors.affiliation: Department of Cell Biology, Division of Medicine, Faculty of Medicine, Imperial Centre for Translation and Experimental Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK.
authors.forename: Elisa A
authors.initials: EA
authors.lastname: Bellomo
authors.affiliation: Department of Neurotrauma and Neurodegeneration.
authors.forename: Wendy
authors.initials: W
authors.lastname: Leadbeater
authors.affiliation: Department of Medical and Molecular Genetics.
authors.forename: Dewi
authors.initials: D
authors.lastname: Astuti
authors.affiliation: Department of Medical and Molecular Genetics.
authors.forename: Joel
authors.initials: J
authors.lastname: Smith
authors.affiliation: School of Clinical and Experimental Medicine, The Medical School School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK and.
authors.forename: Frank
authors.initials: F
authors.lastname: Michelangeli
authors.affiliation: Department of Cell Biology, Division of Medicine, Faculty of Medicine, Imperial Centre for Translation and Experimental Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK.
authors.forename: Guy A
authors.initials: GA
authors.lastname: Rutter
authors.affiliation: Department of Medical and Molecular Genetics t.g.barrett@bham.ac.uk.
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Barrett
mesh_terms: D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004229:Dithiothreitol / Q000494:pharmacology; D005786:Gene Expression Regulation; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism*
chemical_list: D007328:Insulin; D008565:Membrane Proteins; C114987:wolframin protein; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002118:Calcium; D004229:Dithiothreitol