ZnPP reduces autophagy and induces apoptosis, thus aggravating liver ischemia/reperfusion injury in vitro

Int J Mol Med. 2014 Dec;34(6):1555-64. doi: 10.3892/ijmm.2014.1968. Epub 2014 Oct 14.

Abstract

There is growing evidence indicating that autophagy plays a protective role in liver ischemia/reperfusion (IR) injury. Heme oxygenase-1 (HO-1) can also prevent liver IR injury by limiting inflammation and inducing an anti-apoptotic response. Autophagy also plays a crucial role in liver IR injury. The aim of the present study was to investigate the role of HO-1 in liver IR injury and the association between HO-1, autophagy and apoptotic pathways. IR simulation was performed using buffalo rat liver (BRL) cells, and HO-1 activity was either induced by hemin (HIR group) or inhibited by zinc protoporphyrin (ZnPP) (ZIR group). In the HIR and ZIR group, the expression of HO-1 and autophagy-related genes [light chain 3-Ⅱ (LC3-Ⅱ)] was assessed by RT-qPCR and the protein expression of caspases, autophagy-related genes and genes associated with apoptotic pathways (Bax) was detected by western blot anlaysis. The results of RT-PCR revealed the genetically decreased expression of HO-1 and autophagy-related genes in the ZIR group. Similar results were obtained by western blot analysis and immunofluorescence. An ultrastructural analysis revealed a lower number of autophagosomes in the ZIR group; in the HIR group, the number of autophagosomes was increased. The expression of Bax and cytosolic cytochrome c was increased, while that of Bcl-2 was decreased following treatment of the cells with ZnPP prior to IR simulation; the oppostie occurred in the HIR group. Cleaved caspase-3, caspase-9 and poly(ADP-ribose) polymerase (PARP) protein were activated in the IR and ZIR groups. The disruption of mitochondrial membrane potential was also observed in the ZIR group. In general, the downregulation of HO-1 reduced autophagy and activated the mitochondrial apoptotic pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • Apoptosis / genetics
  • Autophagy / drug effects*
  • Autophagy / genetics
  • Blotting, Western
  • Caspases / metabolism
  • Cells, Cultured
  • Enzyme Inhibitors / pharmacology
  • Gene Expression / drug effects
  • Heme Oxygenase-1 / genetics
  • Heme Oxygenase-1 / metabolism
  • Hepatocytes / drug effects*
  • Hepatocytes / metabolism
  • Liver / blood supply
  • Liver / drug effects
  • Membrane Potential, Mitochondrial / drug effects
  • Microscopy, Electron, Transmission
  • Microscopy, Fluorescence
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • Phagosomes / drug effects
  • Phagosomes / metabolism
  • Phagosomes / ultrastructure
  • Poly(ADP-ribose) Polymerases / metabolism
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Protoporphyrins / pharmacology*
  • Rats, Inbred BUF
  • Reperfusion Injury
  • Reverse Transcriptase Polymerase Chain Reaction
  • bcl-2-Associated X Protein / metabolism

Substances

  • Bax protein, rat
  • Enzyme Inhibitors
  • LC3 protein, rat
  • Microtubule-Associated Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Protoporphyrins
  • bcl-2-Associated X Protein
  • zinc protoporphyrin
  • Heme Oxygenase-1
  • Poly(ADP-ribose) Polymerases
  • Caspases