Protein kinase C alterations in the fetal rat brain after global ischemia.

J C Louis,E Magal,E Yavin

doi:10.1016/s0021-9258(19)77631-5

J C Louis, E Magal + Show 1 more

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https://doi.org/10.1016/s0021-9258(19)77631-5

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Abstract

Marked changes in the intracellular localization of brain protein kinase C are evident after global ischemia generated by the restriction of the placental blood flow in the near-term rat embryo. A rapid (5 min) ischemia-dependent translocation of the enzyme from the cytosol to the particulate membrane fraction, which is completely reversible upon reperfusion, is observed. After 30 min of ischemia, substantial losses in protein kinase C activity and content as measured by [3H]phorbol dibutyrate binding are apparent. This is accompanied by a marked increase of a Ca2+-phosphatidylserine-independent kinase activity, already evident after 5 min of ischemia. By 15 or 30 min the total activity of the latter enzyme is equally distributed between the particulate and the cytosol fractions and is more than 3-fold higher in ischemic in comparison to naive animals. Activation and possible deregulation of protein kinase C are proposed to represent an initial step in the pathophysiology of brain ischemia.

Highlights

Surgery-Sprague-Dawley rats at 20 days of gestation were anesthetized by intramuscular injection of 0.1 m1/200 g of body weightof
In protein kinase C activity and content as measured Enzyme Preparation-Frontal lobes from control or ischemic rat by [3H]phorbol dibutyrate binding are apparent. This brain embryos [5] were rapidly excised and homogenized with a is accompanied by a marked increase of a Ca2+-phos- Polytron apparatus in 10 ml of homogenizingbuffer consisting of 20 phatidylserine-independentkinaseactivity, already mM Tris-HC1, pH 7.5, 2 mM EDTA, 0.5 mM EGTA, 2 mM dithioevident after 5 min of ischemia
The resulting pellet was further resuspended in 10 mlof homogenizing buffer as above supplemented with 0.3% Triton X-100 and incubated for 1 h at 4 “C andcentrifuged at 100,000 X g for 1h

Summary

THEJOURNAOLF BIOLOGICCAHLEMISTRY

Vol 263, No 36 Issue of December 25 pp. 19282-19285 1988 0 1988by The American Societ; for Biochemistryand Molecular Biolok. Vol 263, No 36 Issue of December 25 pp. 19282-19285 1988 0 1988by The American Societ; for Biochemistryand Molecular Biolok. Inc. acylglycerol-activated protein kinase C(PKC),’ an enzyme believed to play a pivotal role in the regulation of cell metabolism and function [6,7].PKC has been operationally defined as aninterconvertible soluble, inactive, as well as membranebound, active form. Acylglycerol-activated protein kinase C(PKC),’ an enzyme believed to play a pivotal role in the regulation of cell metabolism and function [6,7].PKC has been operationally defined as aninterconvertible soluble, inactive, as well as membranebound, active form The interplay between these two forms (Receivedfor publication, February 5, 1988) during cerebral ischemia is the subject of this report

MATERIALS ANDMETHODS

DISCUSSION

Findings

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