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Contribution of pH‐dependent group II phospholipase A2 to chemical hypoxic injury in rat hepatocytes
Author(s) -
Wang H,
HarrisonShostak D C,
Lemasters J J,
Herman B
Publication year - 1996
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.10.11.8836046
Subject(s) - phospholipase a2 , propidium iodide , microbiology and biotechnology , immunofluorescence , hypoxia (environmental) , biology , arachidonic acid , hepatocyte , western blot , biochemistry , antibody , chemistry , enzyme , immunology , programmed cell death , apoptosis , organic chemistry , oxygen , gene , in vitro
Numerous studies have suggested that enhanced membrane phospholipid degradation contributes to hypoxic and ischemic injury. Recently, acidosis has been found to potently protect against hypoxic and ischemic injury. To investigate the interrelationships of these two events in hypoxic injury, we studied the role of a pH‐dependent group II phospholipase A2 (PLA2, E.C. 3.1.1.4) in chemical hypoxic injury in rat hepatocytes. Northern blot analysis of RNA extracted from normoxic and hypoxic rat hepatocytes with group II rat liver PLA2‐specific oligonucleotide cDNA probes revealed a 0.9 kb transcript whose abundance was significantly increased in rat hepatocytes within 15 min after initiation of chemical hypoxia and remained high until cells lost viability. Immunofluorescence staining of hepatocytes with polyclonal antibodies that recognize group II PLA2 demonstrated a substantial increase in the level of PLA2 protein in hypoxic rat hepatocytes within 30 min of initiation of hypoxic injury. Treatment of hepatocytes with group II PLA2‐specific anti‐sense DNA oligonucleotides: 1) abolished accumulation of PLA2 protein in hypoxic rat hepatocytes as assessed by immunofluorescence staining with anti‐PLA2 antibodies; 2) decreased the enzymatic activity of PLA2 manifested as decreased arachidonic acid release in hypoxic hepatocytes; and 3) significantly delayed cell death evoked by chemical hypoxia as indicated by a decrease in propidium iodide uptake. These findings suggest that pH‐dependent group II PLA2 plays an important role in chemical hypoxic injury of rat hepatocytes.