Protein kinase C upregulates intercellular adhesion molecule-1 and leukocyte-endothelium interactions in hyperglycemia via activation of endothelial expressed calpain.

ABSTRACT: We tested the hypothesis of a role for the calcium-dependent protease calpain in the endothelial dysfunction induced by hyperglycemic activation of protein kinase C (PKC).Chronic hyperglycemia with insulin deficiency (type 1 diabetes) was induced in rats by streptozotocin. Total PKC and calpain activities, along with activity and expression level of the 2 endothelial-expressed calpains isoforms, ?- and m-calpain, were measured in vascular tissue homogenates by enzymatic assays and Western blot analysis, respectively. Intravital microscopy was used to measure and correlate leukocyte-endothelium interactions with calpain activity in the microcirculation. Expression levels and endothelial localization of the inflammatory adhesion molecule intercellular adhesion molecule-1 were studied by Western blot analysis and immunofluorescence, respectively. The mechanistic role of hyperglycemia alone in the process of PKC-induced calpain activation and actions was also investigated. We found that in the type 1 diabetic vasculature, PKC selectively upregulates the activity of the ?-calpain isoform. Mechanistic studies confirmed a role for hyperglycemia and PKC? in this process. The functional implications of PKC-induced calpain activation were upregulation of endothelial expressed intercellular adhesion molecule-1 and leukocyte-endothelium interactions.Our results uncover the role of ?-calpain in the endothelial dysfunction of PKC. Calpain may represent a novel molecular target for the treatment of PKC-associated diabetic vascular disease.

SUBMITTER: Smolock AR 

PROVIDER: S-EPMC3086836 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature