title: Statins inhibit protein lipidation and induce the unfolded protein response in the non-sterol producing nematode Caenorhabditis elegans.
abstract: Statins are compounds prescribed to lower blood cholesterol in millions of patients worldwide. They act by inhibiting HMG-CoA reductase, the rate-limiting enzyme in the mevalonate pathway that leads to the synthesis of farnesyl pyrophosphate, a precursor for cholesterol synthesis and the source of lipid moieties for protein prenylation. The nematode Caenorhabditis elegans possesses a mevalonate pathway that lacks the branch leading to cholesterol synthesis, and thus represents an ideal organism to specifically study the noncholesterol roles of the pathway. Inhibiting HMG-CoA reductase in C. elegans using statins or RNAi leads to developmental arrest and loss of membrane association of a GFP-based prenylation reporter. The unfolded protein response (UPR) is also strongly activated, suggesting that impaired prenylation of small GTPases leads to the accumulation of unfolded proteins and ER stress. UPR induction was also observed upon pharmacological inhibition of farnesyl transferases or RNAi inhibition of a specific isoprenoid transferase (M57.2) and found to be dependent on both ire-1 and xbp-1 but not on pek-1 or atf-6, which are all known regulators of the UPR. The lipid stores and fatty acid composition were unaffected in statin-treated worms, even though they showed reduced staining with Nile red. We conclude that inhibitors of HMG-CoA reductase or of farnesyl transferases induce the UPR by inhibiting the prenylation of M57.2 substrates, resulting in developmental arrest in C. elegans. These results provide a mechanism for the pleiotropic effects of statins and suggest that statins could be used clinically where UPR activation may be of therapeutic benefit.
authors.affiliation: Department of Cell and Molecular Biology, University of Gothenburg, Sweden.
authors.forename: Catarina
authors.initials: C
authors.lastname: Mörck
authors.forename: Louise
authors.initials: L
authors.lastname: Olsen
authors.forename: Caroline
authors.initials: C
authors.lastname: Kurth
authors.forename: Annelie
authors.initials: A
authors.lastname: Persson
authors.forename: Nadia Jin
authors.initials: NJ
authors.lastname: Storm
authors.forename: Emma
authors.initials: E
authors.lastname: Svensson
authors.forename: John-Olov
authors.initials: JO
authors.lastname: Jansson
authors.forename: Marika
authors.initials: M
authors.lastname: Hellqvist
authors.forename: Annika
authors.initials: A
authors.lastname: Enejder
authors.forename: Nils J
authors.initials: NJ
authors.lastname: Faergeman
authors.forename: Marc
authors.initials: M
authors.lastname: Pilon
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D051228:Geranyltranstransferase / Q000037:antagonists & inhibitors; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D050356:Lipid Metabolism / Q000187:drug effects; D008074:Lipoproteins / Q000378:metabolism; D010641:Phenotype; D017510:Protein Folding / Q000187:drug effects; D017368:Protein Prenylation / Q000187:drug effects; D034622:RNA Interference; D013379:Substrate Specificity
chemical_list: D029742:Caenorhabditis elegans Proteins; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D008074:Lipoproteins; D051228:Geranyltranstransferase