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Updated: May 30, 2026

Comprehensive Analysis of Procoagulant Platelets Exhibiting Features of Necrosis, Apoptosis and Platelet Activation
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Comprehensive Analysis of Procoagulant Platelets Exhibiting Features of Necrosis, Apoptosis and Platelet Activation

Published on: May 23, 2025

Relative contributions of stromal interaction molecule 1 and CalDAG-GEFI to calcium-dependent platelet activation and

F Ahmad1, Y Boulaftali, T K Greene

  • 1Department of Medicine and Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA, USA.

Journal of Thrombosis and Haemostasis : JTH
|August 19, 2011
PubMed

Insights

Stromal interaction molecule 1 (STIM1) and CalDAG-GEFI are crucial for platelet procoagulant activity and thrombin generation. STIM1/SOCE is vital for platelet procoagulant function, while CalDAG-GEFI is essential for platelet aggregation.

Area of Science:

  • Hematology
  • Molecular Biology
  • Cardiovascular Research

Background:

  • Stromal interaction molecule 1 (STIM1) is a key regulator of store-operated calcium entry (SOCE) in platelets.
  • CalDAG-GEFI, a Ca(2+)-sensing guanine nucleotide exchange factor, is critical for platelet Ca(2+) signaling.

Purpose of the Study:

  • To compare the roles of STIM1/SOCE and CalDAG-GEFI in platelet activation and thrombosis.
  • To elucidate the distinct contributions of STIM1 and CalDAG-GEFI to platelet function.

Main Methods:

  • Conditional deletion of the murine Stim1 gene in megakaryocytes/platelets.
  • Utilized CalDAG-GEFI(-/-) and Stim1(fl/fl) PF4-Cre mice for in vitro and in vivo studies.
  • Assessed platelet responses under static and flow conditions, including aggregation, phosphatidylserine exposure, and thrombosis models.

Main Results:

  • CalDAG-GEFI deficiency markedly impaired integrin α(IIb)β(3)-mediated aggregation, unlike STIM1 deficiency.
  • Both STIM1 and CalDAG-GEFI deficiency significantly reduced phosphatidylserine exposure on platelets.
  • STIM1-deficient platelets formed unstable thrombi with delayed fibrin generation; CalDAG-GEFI deficiency abolished platelet accumulation and reduced fibrin generation.

Conclusions:

  • STIM1/SOCE is essential for platelet procoagulant activity but not proadhesive function.
  • STIM1 and CalDAG-GEFI are critical for initial thrombin generation by procoagulant platelets at vascular injury sites.
Abstract

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