title: Involvement of endoplasmic reticulum and autophagy in microcystin-LR toxicity in Vero-E6 and HepG2 cell lines.
abstract: This work investigates the involvement of the endoplasmic reticulum (ER) and autophagy in microcystin-LR (MCLR) toxicity in Vero-E6 and HepG2 cell lines. Additionally, morphological alterations induced by MCLR in lysosomes and mitochondria were studied. Cytotoxicity evaluation showed that pure MCLR and MCLR from LMECYA110 extract induce concentration dependent viability decays after 24h exposure. HepG2 cells showed an increased sensitivity to MCLR than Vero cells, with lower cytotoxic thresholds and EC(50) values. Conversely, LC3B immunofluorescence showed that autophagy is triggered in both cell lines as a survival response to low MCLR concentrations. Furthermore, MCLR induced a MCLR concentration-dependent decrease of GRP94 expression in HepG2 cells while in Vero cells no alteration was observed. This suggests the involvement of the ER in HepG2 apoptosis elicited by MCLR, while in Vero cells ER destructuration could be a consequence of cytoskeleton inflicted damages. Additionally, in both cell lines, lysosomal destabilization preceded mitochondrial impairment which occurred at high toxin concentrations. Although not an early cellular target of MCLR, mitochondria appears to serve as central mediators of different signaling pathways elicited by the organelles involved in MCLR toxicity. As a result, kidney and hepatic cell lines exhibit cell type and dose-dependent mechanisms to overcome MCLR toxicity.
authors.affiliation: Department of Environmental Health, National Health Institute Dr Ricardo Jorge, Av Padre Cruz, 1649-016 Lisbon, Portugal. carina.menezes@insa.min-saude.pt
authors.forename: Carina
authors.initials: C
authors.lastname: Menezes
authors.forename: Elsa
authors.initials: E
authors.lastname: Alverca
authors.forename: Elsa
authors.initials: E
authors.lastname: Dias
authors.forename: Filomena
authors.initials: F
authors.lastname: Sam-Bento
authors.forename: Paulo
authors.initials: P
authors.lastname: Pereira
mesh_terms: D000818:Animals; D001343:Autophagy / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D004721:Endoplasmic Reticulum / Q000187:drug effects*; D056945:Hep G2 Cells; D006801:Humans; D008247:Lysosomes; D008387:Marine Toxins; D008562:Membrane Glycoproteins / Q000378:metabolism; D052998:Microcystins / Q000633:toxicity*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008928:Mitochondria; D014709:Vero Cells
chemical_list: C502070:MAP1LC3B protein, human; D008387:Marine Toxins; D008562:Membrane Glycoproteins; D052998:Microcystins; D008869:Microtubule-Associated Proteins; C053387:endoplasmin; C057862:cyanoginosin LR