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Hyperglycaemia promotes cerebral barrier dysfunction through activation of protein kinase C‐β
Author(s) -
Shao B.,
Bayraktutan U.
Publication year - 2013
Publication title -
diabetes, obesity and metabolism
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.445
H-Index - 128
eISSN - 1463-1326
pISSN - 1462-8902
DOI - 10.1111/dom.12120
Subject(s) - occludin , protein kinase c , blood–brain barrier , nadph oxidase , apocynin , tight junction , chemistry , oxidative stress , barrier function , calphostin c , microbiology and biotechnology , biochemistry , biology , endocrinology , kinase , central nervous system
Aim To examine whether protein kinase C ( PKC ) and associated downstream mechanisms are involved in hyperglycaemia ( HG )‐evoked blood–brain barrier ( BBB ) damage. Methods The activities of total PKC (Peptag assay), NADPH oxidase (lucigenin assay) and matrix metalloproteinase‐2 ( MMP ‐2; gelatin zymography) were measured in human brain microvascular endothelial cells ( HBMEC ) exposed to normoglycaemia (5.5 mM) or HG (25 mM) using the specific assays indicated in parentheses. The integrity and function of the in vitro models of human BBB were assessed by measurements of transendothelial electrical resistance and paracellular flux of permeability markers, respectively. Occludin protein expression was studied by immunoblotting. Results HG significantly compromised the BBB integrity and enhanced total PKC activity to which increases in PKC ‐β and PKC‐β II isoforms contributed the most. Elevations in NADPH oxidase and MMP ‐2 activities and decreases in occludin levels contributed to barrier dysfunction. Selective inhibition of PKC ‐β isoform prevented the changes observed in occludin expression and the aforementioned enzyme activities and thus effectively preserved barrier integrity. Similarly, apocynin, a specific NADPH oxidase inhibitor, also effectively neutralized the effects of HG on barrier integrity, MMP ‐2 activity, occludin expression and PKC ‐β activity. Conclusion HG promotes cerebral‐barrier dysfunction through activation of PKC ‐β and consequent stimulations of oxidative stress and tight junction dissolution.