Protein kinase C activation modulates reversible increase in cortical blood-brain barrier permeability and tight junction protein expression during hypoxia and posthypoxic reoxygenation.
Hypoxia (Hx) is a component of many disease states including stroke. Ischemic stroke occurs when there is a restriction of cerebral blood flow and oxygen to part of the brain. During the ischemic, and subsequent reperfusion phase of stroke, blood-brain barrier (BBB) integrity is lost with tight junction (TJ) protein disruption. However, the mechanisms of Hx and reoxygenation (HR)-induced loss of BBB integrity are not fully understood. We examined the role of protein kinase C (PKC) isozymes in modifying TJ protein expression in a rat model of global Hx. The Hx (6% O(2)) induced increased hippocampal and cortical vascular permeability to 4 and 10 kDa dextran fluorescein isothiocyanate (FITC) and endogenous rat-IgG. Cortical microvessels revealed morphologic changes in nPKC-θ distribution, increased nPKC-θ and aPKC-ζ protein expression, and activation by phosphorylation of nPKC-θ (Thr538) and aPKC-ζ (Thr410) residues after Hx treatment. Claudin-5, occludin, and ZO-1 showed disrupted organization at endothelial cell margins, whereas Western blot analysis showed increased TJ protein expression after Hx. The PKC inhibition with chelerythrine chloride (5 mg/kg intraperitoneally) attenuated Hx-induced hippocampal vascular permeability and claudin-5, PKC (θ and ζ) expression, and phosphorylation. This study supports the hypothesis that nPKC-θ and aPKC-ζ signaling mediates TJ protein disruption resulting in increased BBB permeability.
Willis
Colin L
CL
Department of Pharmacology, College of Medicine, University of Arizona, Tucson, Arizona, USA. cwillis1@une.edu
Meske
Diana S
DS
Davis
Thomas P
TP
D000818:Animals; D053119:Benzophenanthridines / Q000494:pharmacology; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000378:metabolism*; D002540:Cerebral Cortex / Q000098:blood supply*; D042783:Endothelial Cells / Q000201:enzymology / Q000473:pathology; D004789:Enzyme Activation; D005260:Female; D000860:Hypoxia / Q000378:metabolism* / Q000473:pathology; D007527:Isoenzymes / Q000378:metabolism; D055806:Microvessels / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010539:Permeability; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D019108:Tight Junctions / Q000378:metabolism*; D013997:Time Factors
D053119:Benzophenanthridines; D007527:Isoenzymes; D009419:Nerve Tissue Proteins; C016299:chelerythrine; D011493:Protein Kinase C; D010100:Oxygen