IngentaConnect Impaired redistribution of aminophospholipids with distinctive ce...

Authors: Bettache, Nadir¹; Gaffet, Patrick¹; Allegre, Nicolas¹; Maurin, Lucien¹; Toti, Florence²; Freyssinet, Jean Marie²; Bienvenüe, Alain¹

Source: British Journal of Haematology, Volume 101, Number 1, April 1998 , pp. 50-58(9)

Publisher: Blackwell Publishing

Abstract:

We have investigated phospholipid redistribution, membrane vesicle shedding, shape change, and granule release following A23187 activation of platelets from a patient with Scott syndrome, characterized by impaired transmembrane migration of phosphatidylserine (PS) accompanied by haemorrhagic complications, and two of her children. Electron spin resonance spectroscopy measurement of phospholipids redistribution showed that the internalization of PS was unaffected by the disorder but, after activation, PS exposure was significantly reduced in platelets from the homozygous-type patient. Vesicle shedding was also reduced in these platelets. However, the slow redistribution of phosphatidylcholine was similar to that observed in normal platelets. When treated with calpeptin, platelets from the homozygous-type patient, unlike normal or heterozygous Scott syndrome platelets, showed a smoothly rounded shape without filopods after activation. Following A23187 activation of normal platelets, filopod formation was consecutive to the re-exposition of aminophospholipids on the outer leaflet of the plasma membrane, and the existence of a floppase (outward aminoPLs translocase) has been suggested. In homozygous Scott syndrome platelets the deficiency in PS re-exposition, the absence of filopod formation, and low vesicle shedding are correlated with each other, and argue in favour of a disruption of the proposed floppase activity.

Keywords: blood platelet; phospholipids; activation; cell shape; Scott syndrome

Document Type: Original article

DOI: 10.1046/j.1365-2141.1998.00658.x

Affiliations: 1: CNRS-UMR 5539, CC 107, Université Montpellier II, Montpellier, 2: Institut d'Hématologie et d'Immunologie, Faculté de Médecine, Université Louis Pasteur, Strasbourg, France

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Impaired redistribution of aminophospholipids with distinctive cell shape change during Ca2+-induced activation of platelets from a patient with Scott syndrome

Impaired redistribution of aminophospholipids with distinctive cell shape change during Ca²⁺-induced activation of platelets from a patient with Scott syndrome