title: Misfolded proteins inhibit proliferation and promote stress-induced death in SV40-transformed mammalian cells.
abstract: Protein misfolding is implicated in neurodegenerative diseases and occurs in aging. However, the contribution of the misfolded ensembles to toxicity remains largely unknown. Here we introduce 2 primate cell models of destabilized proteins devoid of specific cellular functions and interactors, as bona fide misfolded proteins, allowing us to isolate the gain-of-function of non-native structures. Both GFP-degron and a mutant chloramphenicol-acetyltransferase fused to GFP (GFP-Δ9CAT) form perinuclear aggregates, are degraded by the proteasome, and colocalize with and induce the chaperone Hsp70 (HSPA1A/B) in COS-7 cells. We find that misfolded proteins neither significantly compromise chaperone-mediated folding capacity nor induce cell death. However, they do induce growth arrest in cells that are unable to degrade them and promote stress-induced death upon proteasome inhibition by MG-132 and heat shock. Finally, we show that overexpression of all heat-shock factor-1 (HSF1) and Hsp70 proteins, as well as wild-type and deacetylase-deficient (H363Y) SIRT1, rescue survival upon stress, implying a noncatalytic action of SIRT1 in response to protein misfolding. Our study establishes a novel model and extends our knowledge on the mechanism of the function-independent proteotoxicity of misfolded proteins in dividing cells.
authors: Department of Medical Chemistry, Semmelweis University, Budapest, Hungary.
authors: Mehmet Alper
authors: MA
authors: Arslan
authors: Maria
authors: M
authors: Chikina
authors: Péter
authors: P
authors: Csermely
authors: Csaba
authors: C
authors: Soti
mesh_terms: D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D016923:Cell Death / Q000502:physiology; D049109:Cell Proliferation; D002472:Cell Transformation, Viral; D002522:Chlorocebus aethiops; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D000076249:Heat Shock Transcription Factors; D008954:Models, Biological; D046912:Multiprotein Complexes; D011401:Promoter Regions, Genetic; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D017510:Protein Folding; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013539:Simian virus 40; D056564:Sirtuin 1 / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D017931:DNA Primers; D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D046912:Multiprotein Complexes; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D046988:Proteasome Endopeptidase Complex; D056564:Sirtuin 1