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Identification of Intracellular Signaling Events Induced in Viable Cells by Interaction with Neighboring Cells Undergoing Apoptotic Cell Death
09:18

Identification of Intracellular Signaling Events Induced in Viable Cells by Interaction with Neighboring Cells Undergoing Apoptotic Cell Death

Published on: December 27, 2016

Cellular apoptosis is associated with increased caveolin-1 expression in macrophages

Peter Gargalovic1, Ladislav Dory

  • 1Department of Molecular Biology & Immunology, The University of North Texas Health Science Center at Fort Worth, TX 76107, USA.

Journal of Lipid Research
|June 5, 2003
PubMed

Insights

Macrophage apoptosis involves increased caveolin-1 ( CAV1 ) expression, a key event independent of protein synthesis. This suggests CAV1 may facilitate phosphatidylserine externalization in apoptotic macrophages.

Area of Science:

  • Immunology
  • Cell Biology
  • Biochemistry

Background:

  • Macrophage apoptosis influences immune response, atherosclerotic plaque stability, and cellular debris clearance.
  • Caveolin-1 (CAV1) has been implicated in apoptosis regulation in non-macrophage cell types.
  • Understanding macrophage apoptosis mechanisms is crucial for various physiological and pathological processes.

Purpose of the Study:

  • To investigate the role and expression of caveolin-1 during macrophage apoptosis.
  • To determine if CAV1 expression changes in response to different apoptotic stimuli in macrophages.
  • To elucidate the relationship between CAV1, phosphatidylserine (PS) externalization, and caspase activation in apoptotic macrophages.

Main Methods:

  • Treatment of mouse peritoneal macrophages with unrelated apoptotic agents (simvastatin, camptothecin, glucose deprivation).
  • Assessment of apoptosis via cell morphology, annexin V labeling, and DNA fragmentation.
  • Analysis of caveolin-1 and caveolin-2 expression levels.
  • Investigation of CAV1 localization in lipid rafts and its colocalization with PS.
  • Evaluation of the effect of cycloheximide on CAV1 increase during apoptosis.

Main Results:

  • Various apoptotic stimuli caused a significant increase in CAV1 expression in macrophages, while caveolin-2 remained unchanged.
  • CAV1 was found in lipid rafts and colocalized with phosphatidylserine (PS) on the surface of apoptotic macrophages.
  • The increase in CAV1 and PS externalization occurred early in apoptosis and were independent of caspase activation and new protein synthesis.
  • Cycloheximide did not inhibit the apoptosis-induced increase in CAV1 levels.

Conclusions:

  • Elevated caveolin-1 expression is a characteristic feature of the apoptotic phenotype in macrophages.
  • Caveolin-1 may play a functional role in the efficient externalization of phosphatidylserine on the surface of apoptotic macrophages.
  • CAV1-mediated PS externalization could be a critical step in the clearance of apoptotic macrophages by phagocytes.

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