Augmenter of liver regeneration: an important intracellular survival factor for hepatocytes

J Hepatol. 2008 Apr;48(4):578-88. doi: 10.1016/j.jhep.2007.12.010. Epub 2008 Jan 28.

Abstract

Background/aims: Augmenter of liver regeneration (ALR), a protein synthesized and stored in hepatocytes, is associated with mitochondria, and possesses sulfhydryl oxidase and cytochrome c reductase activities. We sought to determine the effects of ALR depletion in hepatocytes by antisense oligonucleotide transfection.

Methods: Rat hepatocytes in primary culture were transfected with antisense oligonucleotide for ALR mRNA (ALR-AS) or scrambled oligonucleotide. Various analyses were performed at times up to 24h after transfection.

Results: Treatment with ALR-AS caused a decrease in ALR mRNA, cellular depletion of ALR protein primarily from mitochondria, and decreased viability. Flow cytometric analysis of ALR-AS-transfected hepatocytes stained with annexin-Vcy3 and 7-aminoactinomycin D revealed apoptosis as the predominant cause of death up to 6h; incubation beyond this time resulted in necrosis in addition to apoptosis. ALR-AS-transfection caused release of mitochondrial cytochrome c, activation of caspase-3, profound reduction in the ATP content, and cellular release of LDH. Inhibition of caspase-3 inhibited the early phase of ALR-AS-induced death but not the late phase that included ALR and LDH release.

Conclusions: These results suggest that ALR is critically important for the survival of hepatocytes by its association with mitochondria and regulation of ATP synthesis.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / biosynthesis
  • Animals
  • Apoptosis
  • Cell Count
  • Cell Survival / physiology
  • Cells, Cultured
  • Flow Cytometry
  • Hepatocytes / cytology*
  • Hepatocytes / metabolism
  • Intracellular Fluid / metabolism*
  • Mitochondria, Liver / genetics
  • Mitochondria, Liver / metabolism
  • Oligonucleotides, Antisense / genetics
  • Proteins / genetics
  • Proteins / metabolism*
  • RNA, Messenger / genetics
  • Rats
  • Reverse Transcriptase Polymerase Chain Reaction
  • Spectrophotometry
  • Transfection

Substances

  • Oligonucleotides, Antisense
  • Proteins
  • RNA, Messenger
  • augmenter of liver regeneration factor
  • Adenosine Triphosphate