title: ER stress in human hepatic cells treated with Efavirenz: mitochondria again.
abstract: OBJECTIVE
  ER stress is associated with a growing number of liver diseases, including drug-induced hepatotoxicity. The non-nucleoside analogue reverse transcriptase inhibitor Efavirenz, a cornerstone of the multidrug strategy employed to treat HIV1 infection, has been related to the development of various adverse events, including metabolic disturbances and hepatic toxicity, the mechanisms of which remain elusive. Recent evidence has pinpointed a specific mitochondrial effect of Efavirenz in human hepatic cells. This study assesses the induction of ER stress by Efavirenz in the same model and the implication of mitochondria in this process.
  
  
  METHODS
  Primary human hepatocytes and Hep3B were treated with clinically relevant concentrations of Efavirenz and parameters of ER stress were studied using standard cell biology techniques.
  
  
  RESULTS
  ER stress markers, including CHOP and GRP78 expression (both protein and mRNA), phosphorylation of eIF2α, and presence of the spliced form of XBP1 were upregulated. Efavirenz also enhanced cytosolic Ca(2+) content and induced morphological changes in the ER suggestive of ER stress. This response was greatly attenuated in cells with altered mitochondrial function (Rho°). The effects of Efavirenz on the ER, and particularly in regard to the mitochondrial involvement, differed from those elicited by a standard pharmacological ER stressor.
  
  
  CONCLUSIONS
  This newly discovered mechanism of cellular insult involving ER stress and UPR response may help comprehend the hepatic toxicity that has been associated with the widespread and life-long use of Efavirenz. In addition, the specificity of the actions of Efavirenz observed expands our knowledge of the mechanisms that trigger ER stress and shed some light on the mitochondria/ER interplay in drug-induced hepatic challenge.
authors.affiliation: Departamento de Farmacología, Facultad de Medicina, Universidad de Valencia, Valencia, Spain; CIBERehd, Valencia, Spain. Electronic address: nadezda.apostolova@uv.es.
authors.forename: Nadezda
authors.initials: N
authors.lastname: Apostolova
authors.forename: Leysa J
authors.initials: LJ
authors.lastname: Gomez-Sucerquia
authors.forename: Fernando
authors.initials: F
authors.lastname: Alegre
authors.forename: Haryes A
authors.initials: HA
authors.lastname: Funes
authors.forename: Victor M
authors.initials: VM
authors.lastname: Victor
authors.forename: Maria D
authors.initials: MD
authors.lastname: Barrachina
authors.forename: Ana
authors.initials: A
authors.lastname: Blas-Garcia
authors.forename: Juan V
authors.initials: JV
authors.lastname: Esplugues
mesh_terms: D000480:Alkynes; D019380:Anti-HIV Agents / Q000009:adverse effects; D048588:Benzoxazines / Q000009:adverse effects*; D015415:Biomarkers / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D003521:Cyclopropanes; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D046529:Microscopy, Electron, Transmission; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D008954:Models, Biological; D018894:Reverse Transcriptase Inhibitors / Q000009:adverse effects; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D000480:Alkynes; D019380:Anti-HIV Agents; D048588:Benzoxazines; D015415:Biomarkers; D003521:Cyclopropanes; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D018894:Reverse Transcriptase Inhibitors; D019284:Thapsigargin; C514824:reverse transcriptase, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase; C098320:efavirenz; D002118:Calcium
keywords: ATF4; C/EBP-homologous protein; CCCP; CHOP; Cyclophylin A; CypA; EFV; ER; ER stress; Efavirenz; GRP78; HCV; HIV; HIV1; Hepatotoxicity; LPV; Mitochondria; PI; ROS; RTV; Side effects; TG; TMRM; UPR; WB; Western blotting; X-box binding protein 1; XBP1; activating transcription factor 4; cART; carbonyl cyanide m-chloro phenyl hydrazone; combined antiretroviral therapy; eIF2α; efavirenz; endoplasmic reticulum; eukaryotic translation initiation factor 2 alpha; glucose-regulated protein 78; hepatitis C virus; human immunodeficiency virus 1; lopinavir; mitochondrial DNA; mitochondrial membrane potential; mtDNA; protease inhibitor; reactive oxygen species; ritonavir; tetramethyl rhodamine methyl ester; thapsigargin; unfolded protein response; ΔΨ(m)