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Protein phosphatase‐1I activation in brain following cardiac arrest and resuscitation
Author(s) -
Platholi Jimcy,
Heerdt Paul,
Tung H.Y. Lim,
Hemmings Hugh
Publication year - 2007
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.21.5.a618-d
Subject(s) - ischemia , phosphatase , protein subunit , resuscitation , brain ischemia , protein phosphatase 2 , chemistry , medicine , microbiology and biotechnology , biochemistry , biology , anesthesia , phosphorylation , gene
The signaling pathways that couple cerebral ischemia to cell death and protective mechanisms have not been elucidated. Protein phosphatase‐1 (PP‐1) interacts with and dephosphorylates multiple protein regulators of cellular energy metabolism, ionic balance and apoptotic cell death. We report that a Mg 2+ /ATP‐dependent form of PP‐1 associated with inhibitor‐2 (PP‐1I) is activated in brain by ~2‐fold following cardiac arrest and resuscitation in an intact animal model of severe transient global cerebral ischemia. PP‐1I from control non‐ischemic and ischemic pig brain was purified to near homogeneity. The properties, subunit compositions and regulation of PP‐1I purified from control non‐ischemic pig brain was distinct from PP‐1I purified from ischemic pig brain. Six major proteins (C‐TAK1, Rab GDP dissociation protein b, protein phosphatase‐1a catalytic subunit [PP‐1acat], 14‐3‐3g and inhibitor‐2 [I‐2] were identified by SDS/PAGE followed by MALDI ToF mass spectrometry from the non‐ischemic brain. PP‐1acat, I‐2 and 14‐3‐3g existed as a macromolecular complex as confirmed by co‐immunoprecipitation. Both PP‐1acat and reconstituted PP‐1acat:phosphoI‐2 were inhibited directly by 14‐3‐3g. PP‐1I purified from ischemic brain contained less 14‐3‐3g than that purified from non‐ischemic brain indicating that activation of PP‐1I following cardiac arrest and resuscitation involves dissociation of inhibitory 14‐3‐3g. This is the first demonstration of PP‐1I activation in a clinically relevant model of global cerebral ischemia in vivo . This work was supported by the Department of Anesthesiology of Weill Medical College of Cornell University and by the Phaekhim‐Sekekos Foundation for Biomedical Research