Abstract Number: PB0963
Meeting: ISTH 2021 Congress
Theme: Platelets and Megakaryocytes » Platelet Function and Interactions
Background: The amino acid sequence 106-126 of prion proteins i.e., PrP(106-126) is highly amyloidogenic. It leads to prion-mediated pathologies. As PrP(106-126) is known to be expressed in blood following leakage from brain tissue in prion diseases, we aimed to investigate the modalities of its pathological effects in human platelets.
Aims: We aimed to investigate:
1. Calpain activity
2. Facilitation of talin degradation
3. Shedding of Platelet-derived microparticles (PMPs).
Methods: 1. Isolation of human blood platelets in resting state by differential centrifugation
2. Platelet aggregation / agglutination and dense granule secretion
3. Flow cytometric based analyses
4. Spectrofluorometric measurement of intracellular free calcium
5. Confocal microscopy for calcium imaging
6. Calpain activity assay
7. Western blot analyses.
Results: 1. PrP(106-126) induces platelet activation
2. PrP(106-126) induces rise in intracellular free calcium in platelets
3. PrP(106-126)-induced rise in intracellular free calcium in platelets was found to involve transient receptor potential channel (TRPC) proteins
4. PrP(106-126) stimulates calpain activity in human platelets
5. PrP(106-126) facilitates talin degradation to release the platelet-derived microparticles
6. PrP(106-126) induces shedding of platelet-derived microparticles (PMPs).
PrP(106-126)-induced partial partial proteolysis of cytoskeleton protein ‘talin’Figure-1. Prion-induced partial proteolysis of cytoskeleton protein ‘talin’
Flow cytometric analyses laid histogram representation of PE-labeled annexin-V binding to platelet-derived microparticles (PMPs)Figure-2. Histogram representation of Phycoerrythtrin (PE)-labeled annexin-V binding to PMPsConclusions: Our findings suggested that PrP(106-126) induced 30-fold rise in intracellular rise in calcium. It was attributable to influx from extracellular fluid. Calcium mobilization was associate with 8-10 fold stimulation in activity of thiol protease that laid to partial cleavage of cytoskeleton-associated protein talin and extensive shedding of platelet-derived microparticles. Both proteolysis of talin and microparticle release were precluded by calpeptin i.e., a specific inhibitor of calpain. As microparticles are endowed with phoshpatidylserine (PS)-enriched surface and so are procoagulant in nature, exposure to prion favors thrombogenic state.
To cite this abstract in AMA style:
Prakash Gaire C, Lala Mallick R, Kumar Karn S, Thapa R. Stimulation of Calpain Activity, Facilitation of Talin Degradation and Shedding of PMPs Exist as the Modalities of Prion-mediated Pathological Effects in Human Platelets [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/stimulation-of-calpain-activity-facilitation-of-talin-degradation-and-shedding-of-pmps-exist-as-the-modalities-of-prion-mediated-pathological-effects-in-human-platelets/. Accessed November 29, 2023.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/stimulation-of-calpain-activity-facilitation-of-talin-degradation-and-shedding-of-pmps-exist-as-the-modalities-of-prion-mediated-pathological-effects-in-human-platelets/