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SDF-1α/CXCR4 Signaling in Lipid Rafts Induces Platelet Aggregation via PI3 Kinase-Dependent Akt Phosphorylation

Hiroko Ohtsuka1,2, Tomohiro Iguchi1, Moyuru Hayashi1

  • 1Laboratory of Biomembrane, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.

Plos One
|January 11, 2017
PubMed

Insights

Stromal cell-derived factor-1α (SDF-1α) binding to CXCR4 triggers platelet aggregation via PI3K-dependent Akt phosphorylation. This signaling pathway, localized in lipid rafts, is crucial for platelet activation and aggregation.

Area of Science:

  • Hematology
  • Cell Signaling
  • Molecular Biology

Background:

  • Platelet aggregation plays a critical role in hemostasis and thrombosis.
  • Stromal cell-derived factor-1α (SDF-1α) is known to induce platelet aggregation.
  • The precise molecular mechanisms underlying SDF-1α-mediated platelet activation are not fully elucidated.

Purpose of the Study:

  • To investigate the role of phosphatidylinositol 3 kinase (PI3K) and Akt signaling in SDF-1α-induced platelet aggregation.
  • To determine the involvement of lipid rafts in the SDF-1α/CXCR4 signaling pathway.
  • To identify key signaling molecules downstream of Akt in this process.

Main Methods:

  • Human platelets were treated with SDF-1α and inhibitors of CXCR4, PI3K, and Akt.
  • Western blotting was used to assess the phosphorylation of Akt, PDK1, GSK3β, and myosin light chain.
  • Sucrose density gradient centrifugation was employed to analyze the localization of signaling proteins in lipid rafts.

Main Results:

  • SDF-1α induced Akt phosphorylation at Thr308 and Ser473 in human platelets.
  • Inhibition of CXCR4, PI3K, or Akt significantly reduced SDF-1α-induced platelet aggregation and Akt phosphorylation.
  • Key signaling proteins, including CXCR4, G proteins, PI3K, and Akt, were found to be localized within detergent-resistant membrane rafts.

Conclusions:

  • SDF-1α/CXCR4 signaling within lipid rafts is essential for PI3K-dependent Akt activation and subsequent platelet aggregation.
  • This pathway represents a potential therapeutic target for modulating platelet function in various clinical conditions.

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