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Involvement of endoplasmic reticulum and autophagy in microcystin-LR toxicity in Vero-E6 and HepG2 cell lines

Carina Menezes1, Elsa Alverca, Elsa Dias

  • 1Department of Environmental Health, National Health Institute Dr Ricardo Jorge, Av Padre Cruz, 1649-016 Lisbon, Portugal. carina.menezes@insa.min-saude.pt

Toxicology in Vitro : an International Journal Published in Association with BIBRA
|September 27, 2012
PubMed

Insights

Microcystin-LR (MCLR) triggers autophagy as a survival response in liver and kidney cells. Organelle damage, including endoplasmic reticulum, lysosomes, and mitochondria, occurs in a cell-type and dose-dependent manner, influencing toxicity mechanisms.

Area of Science:

  • Cell Biology
  • Toxicology
  • Molecular Biology

Background:

  • Microcystin-LR (MCLR) is a potent cyanotoxin with significant health implications.
  • Understanding cellular responses to MCLR is crucial for assessing its toxicity.
  • The roles of endoplasmic reticulum (ER), autophagy, lysosomes, and mitochondria in MCLR toxicity are not fully elucidated.

Purpose of the Study:

  • To investigate the involvement of ER and autophagy in MCLR toxicity in HepG2 and Vero-E6 cells.
  • To examine morphological alterations in lysosomes and mitochondria induced by MCLR.
  • To compare the sensitivity and cellular responses of HepG2 and Vero-E6 cells to MCLR.

Main Methods:

  • Cytotoxicity assays to determine cell viability and EC(50) values.
  • LC3B immunofluorescence to assess autophagy activation.
  • Analysis of GRP94 expression to evaluate ER stress.
  • Morphological studies of lysosomes and mitochondria.

Main Results:

  • MCLR induced dose-dependent cell death in both HepG2 and Vero-E6 cells, with HepG2 cells being more sensitive.
  • Autophagy (LC3B) was activated as a survival mechanism at lower MCLR concentrations.
  • MCLR decreased GRP94 expression in HepG2 cells, suggesting ER involvement in apoptosis, while Vero cells showed ER destructuration possibly due to cytoskeletal damage.
  • Lysosomal destabilization preceded mitochondrial impairment, which occurred at higher MCLR concentrations.
  • Mitochondria act as central mediators in signaling pathways related to MCLR toxicity.

Conclusions:

  • HepG2 and Vero-E6 cells employ distinct, dose-dependent mechanisms to counteract MCLR toxicity.
  • ER stress and autophagy play significant roles in the cellular response to MCLR.
  • Lysosomes and mitochondria are affected sequentially, with mitochondria mediating downstream signaling.

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