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Caveolin-1-dependent apoptosis induced by fibrin degradation products

Yi-He Guo1, Irene Hernandez, Berend Isermann

  • 1Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI 53226-3548, USA.

Blood
|December 17, 2008
PubMed

Insights

Fibrin degradation products induce cell death by entering cells via caveolae, mediated by a specific fibrin fragment E segment. This process, crucial in the placenta, involves mitochondrial dysfunction and caspase activation.

Area of Science:

  • Molecular Biology
  • Cellular Biology
  • Hematology

Background:

  • Thrombomodulin deficiency in mice leads to fibrinolytic degradation products (FDP) inducing apoptotic cell death in placental polyploid trophoblast giant cells.
  • The specific mechanisms and broader implications of FDP-induced apoptosis are not fully understood.

Purpose of the Study:

  • To investigate the conserved bioactivity of human FDP and identify the specific molecular components responsible for inducing apoptosis.
  • To elucidate the cellular internalization mechanisms and signaling pathways involved in FDP-mediated cell death.

Main Methods:

  • Characterization of human FDP bioactivity and identification of apoptosis-inducing segments.
  • Investigation of cellular internalization pathways, including caveolin-1-dependent endocytosis.
  • Analysis of mitochondrial function and caspase activation in response to FDP exposure.

Main Results:

  • Human FDP exhibit conserved proapoptotic activity, not limited to trophoblast cells, associated with fibrin fragment E (FnE).
  • Apoptosis is largely RGD-independent, requiring caveolin-1-dependent FnE internalization mediated by the Aalpha52-81 epitope.
  • The Aalpha17-37 segment contains the primary apoptotic activity, dependent on a neoepitope and caspase 9/3 activation, leading to mitochondrial dysfunction.

Conclusions:

  • A novel mechanism links fibrin degradation to cell death via FnE internalization and caspase-dependent apoptosis, particularly relevant in the placenta.
  • The findings reveal specific molecular determinants (Aalpha52-81 for internalization, Aalpha17-37 for apoptosis) of FDP bioactivity.
  • This pathway may contribute to vascular pathologies associated with fibrinolysis in non-placental tissues.

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