Calpain inhibition stabilizes the platelet proteome and reactivity in diabetes.
Platelets from patients with diabetes are hyperreactive and demonstrate increased adhesiveness, aggregation, degranulation, and thrombus formation, processes that contribute to the accelerated development of vascular disease. Part of the problem seems to be dysregulated platelet Ca(2+) signaling and the activation of calpains, which are Ca(2+)-activated proteases that result in the limited proteolysis of substrate proteins and subsequent alterations in signaling. In the present study, we report that the activation of μ- and m-calpain in patients with type 2 diabetes has profound effects on the platelet proteome and have identified septin-5 and the integrin-linked kinase (ILK) as novel calpain substrates. The calpain-dependent cleavage of septin-5 disturbed its association with syntaxin-4 and promoted the secretion of α-granule contents, including TGF-β and CCL5. Calpain was also released by platelets and cleaved CCL5 to generate a variant with enhanced activity. Calpain activation also disrupted the ILK-PINCH-Parvin complex and altered platelet adhesion and spreading. In diabetic mice, calpain inhibition reversed the effects of diabetes on platelet protein cleavage, decreased circulating CCL5 levels, reduced platelet-leukocyte aggregate formation, and improved platelet function. The results of the present study indicate that diabetes-induced platelet dysfunction is mediated largely by calpain activation and suggest that calpain inhibition may be an effective way of preserving platelet function and eventually decelerating atherothrombosis development.
Institute for Vascular Signalling, Centre for Molecular Medicine, Goethe University, Theodor-Stern-Kai 7, Frankfurt am Main, Germany.
Voahanginirina
V
Randriamboavonjy
Johann
J
Isaak
Amro
A
Elgheznawy
Frank
F
Pistrosch
Timo
T
Frömel
Xiaoke
X
Yin
Klaus
K
Badenhoop
Heinrich
H
Heide
Manuel
M
Mayr
Ingrid
I
Fleming
D000328:Adult; D000368:Aged; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism; D020013:Calcium Signaling; D002154:Calpain / Q000037:antagonists & inhibitors* / Q000097:blood* / Q000172:deficiency / Q000235:genetics; D016022:Case-Control Studies; D018797:Cell Cycle Proteins / Q000097:blood; D018946:Chemokine CCL5 / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000188:drug therapy; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008875:Middle Aged; D000077205:Pioglitazone; D015539:Platelet Activation / Q000187:drug effects / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000097:blood; D040901:Proteomics; D058112:Septins / Q000097:blood; D045162:Thiazolidinediones / Q000627:therapeutic use; D000099200:Scaffold Protein ILK
D001798:Blood Proteins; D002154:Calpain; D018797:Cell Cycle Proteins; D018946:Chemokine CCL5; D007004:Hypoglycemic Agents; D000077205:Pioglitazone; D017346:Protein Serine-Threonine Kinases; D058112:Septins; D045162:Thiazolidinediones; D000099200:Scaffold Protein ILK; C483024:CCL5 protein, human; C449000:m-calpain; C449002:mu-calpain; C109366:SEPTIN5 protein, human