Apoptosis, autophagy and ER stress in mevalonate cascade inhibition-induced cell death of human atrial fibroblasts.
3-hydroxy-3-methyl-glutaryl-CoA reductase inhibitors (statins) are cholesterol-lowering drugs that exert other cellular effects and underlie their beneficial health effects, including those associated with myocardial remodeling. We recently demonstrated that statins induces apoptosis and autophagy in human lung mesenchymal cells. Here, we extend our knowledge showing that statins simultaneously induces activation of the apoptosis, autophagy and the unfolded protein response (UPR) in primary human atrial fibroblasts (hATF). Thus we tested the degree to which coordination exists between signaling from mitochondria, endoplasmic reticulum and lysosomes during response to simvastatin exposure. Pharmacologic blockade of the activation of ER-dependent cysteine-dependent aspartate-directed protease (caspase)-4 and lysosomal cathepsin-B and -L significantly decreased simvastatin-induced cell death. Simvastatin altered total abundance and the mitochondrial fraction of proapoptotic and antiapoptotic proteins, while c-Jun N-terminal kinase/stress-activated protein kinase mediated effects on B-cell lymphoma 2 expression. Chemical inhibition of autophagy flux with bafilomycin-A1 augmented simvastatin-induced caspase activation, UPR and cell death. In mouse embryonic fibroblasts that are deficient in autophagy protein 5 and refractory to autophagy induction, caspase-7 and UPR were hyper-induced upon treatment with simvastatin. These data demonstrate that mevalonate cascade inhibition-induced death of hATF manifests from a complex mechanism involving co-regulation of apoptosis, autophagy and UPR. Furthermore, autophagy has a crucial role in determining the extent of ER stress, UPR and permissiveness of hATF to cell death induced by statins.
Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada.
S
S
Ghavami
B
B
Yeganeh
G L
GL
Stelmack
H H
HH
Kashani
P
P
Sharma
R
R
Cunnington
S
S
Rattan
K
K
Bathe
T
T
Klonisch
I M C
IM
Dixon
D H
DH
Freed
A J
AJ
Halayko
D017209:Apoptosis; D001343:Autophagy; D053179:Caspase 7 / Q000378:metabolism; D061945:Caspase Inhibitors / Q000494:pharmacology; D053471:Caspases, Initiator / Q000378:metabolism; D016923:Cell Death; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D059865:Endoplasmic Reticulum Stress; D004789:Enzyme Activation; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D006325:Heart Atria / Q000166:cytology; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D008798:Mevalonic Acid / Q000378:metabolism* / Q000494:pharmacology; D009206:Myocardium / Q000166:cytology*; D015398:Signal Transduction; D019821:Simvastatin / Q000494:pharmacology; D056811:Unfolded Protein Response / Q000187:drug effects
D061945:Caspase Inhibitors; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D019821:Simvastatin; C093516:CASP4 protein, human; D053179:Caspase 7; D053471:Caspases, Initiator; D008798:Mevalonic Acid