title: Protein refolding in peroxisomes is dependent upon an HSF1-regulated function.
abstract: Post-heat shock refolding of luciferase requires chaperones. Expression of a dominant negative HSF1 mutant (dnHSF1), which among other effects depletes cells of HSF1-regulated chaperones, blocked post-heat shock refolding of luciferase targeted to the cytoplasm, nucleus, or peroxisomes, while refolding of endoplasmic reticulum (ER)-targeted luciferase was inhibited by about 50 %. Luciferase refolding in the cytoplasm could be partially restored by expression of HSPA1A and fully by both HSPA1A and DNAJB1. For full refolding of ER luciferase, HSPA1A expression sufficed. Neither nuclear nor peroxisomal refolding was rescued by HSPA1A. A stimulatory effect of DNAJB1 on post-heat shock peroxisomal luciferase refolding was seen in control cells, while refolding in the cytoplasm or nucleus in control cells was inhibited by DNAJB1 expression in the absence of added HSPA1A. HSPB1 also improved refolding of peroxisomal luciferase in control cells, but not in dnHSF1 expressing cells. HSP90, HSPA5, HSPA6, and phosphomevalonate kinase (of which the synthesis is also downregulated by dnHSF1) had no effect on peroxisomal refolding in either control or chaperone-depleted cells. The chaperone requirement for post-heat shock refolding of peroxisomal luciferase in control cells is thus unusual in that it can be augmented by DNAJB1 or HSPB1 but not by HSPA1A; in dnHSF1 expressing cells, expression of none of the (co)-chaperones tested was effective, and an as yet to be identified, HSF1-regulated function is required.
authors.affiliation: Department of Biomolecular Chemistry, Radboud University Nijmegen, The Netherlands.
authors.forename: Lonneke
authors.initials: L
authors.lastname: Heldens
authors.forename: Siebe T
authors.initials: ST
authors.lastname: van Genesen
authors.forename: Lars L P
authors.initials: LL
authors.lastname: Hanssen
authors.forename: Jurre
authors.initials: J
authors.lastname: Hageman
authors.forename: Harm H
authors.initials: HH
authors.lastname: Kampinga
authors.forename: Nicolette H
authors.initials: NH
authors.lastname: Lubsen
mesh_terms: D004268:DNA-Binding Proteins / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D017930:Genes, Reporter; D057809:HEK293 Cells; D050956:HSP40 Heat-Shock Proteins / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D020675:Peroxisomes / Q000378:metabolism*; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000378:metabolism; D058849:Protein Refolding; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; C494647:DNAJB1 protein, human; D000091342:Endoplasmic Reticulum Chaperone BiP; C000619706:HSF1 protein, human; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; C490786:HSPA1A protein, human; C000717247:HSPA5 protein, human; C544598:HSPA6 protein, human; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D014157:Transcription Factors; D008156:Luciferases; D017856:Phosphotransferases (Phosphate Group Acceptor); C022371:phosphomevalonate kinase