title: Platelet storage under in vitro condition is associated with calcium-dependent apoptosis-like lesions and novel reorganization in platelet cytoskeleton.
abstract: Platelets are cleared from circulation after a life span of 8-10 days. The molecular mechanisms underlying platelet senescence remain poorly characterized. Here we report that, progressive functional impairment in the platelets incubated in vitro in a plasma-free isotonic medium for up to 24 h at 37 degrees C is associated with release of cytochrome c from platelet mitochondria and cleavage of procaspase-9, but without evidence of caspase-3 activation. Concomitantly, there was proteolysis of survival proteins like focal adhesion kinase, Src, gelsolin, and specific cytoskeleton-associated peptides, in a manner regulated by extracellular calcium and calpain activity. Cytoskeleton played a critical role as evidenced from the association of these proteins and their degradation products, as well as procaspase-3 and the actin regulatory small GTPase, CDC42Hs, with the cytoskeleton of the stored platelets. The cytoskeletal enrichment with specific proteins was not associated with increase in the content of F-actin and was cytochalasin-resistant, thus signifying a novel mechanism of interaction of the translocating proteins with the pre-existing cytoskeleton. There was progressive exposure of phosphatidylserine on the outer leaflet of platelet membrane and specific electron microscopic changes suggestive of apoptotic lesions. Based on these observations we discuss the caspase-independent but calpain-mediated signaling events in the stored platelets resembling the features of apoptosis in the nucleated cells.
authors.affiliation: Department of Biochemistry, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India.
authors.forename: Vinita
authors.initials: V
authors.lastname: Wadhawan
authors.forename: Zubair A
authors.initials: ZA
authors.lastname: Karim
authors.forename: Saikat
authors.initials: S
authors.lastname: Mukhopadhyay
authors.forename: Ramkrishna
authors.initials: R
authors.lastname: Gupta
authors.forename: Madhu
authors.initials: M
authors.lastname: Dikshit
authors.forename: Debabrata
authors.initials: D
authors.lastname: Dash
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D001792:Blood Platelets / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D001793:Blood Preservation; D002118:Calcium / Q000378:metabolism*; D002154:Calpain / Q000037:antagonists & inhibitors / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D016895:Culture Media, Serum-Free; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure; D003600:Cytosol / Q000201:enzymology; D004151:Dipeptides / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D018260:Gelsolin / Q000378:metabolism; D006801:Humans; D008928:Mitochondria / Q000201:enzymology; D010718:Phosphatidylserines / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D013917:Thrombin / Q000494:pharmacology; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D016895:Culture Media, Serum-Free; D015853:Cysteine Proteinase Inhibitors; D004151:Dipeptides; D018260:Gelsolin; D010718:Phosphatidylserines; C071482:calpeptin; D045304:Cytochromes c; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D019061:src-Family Kinases; D013917:Thrombin; D002154:Calpain; D020169:Caspases; D002118:Calcium