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Cell death: a new Par-4 the TRAIL

Lori S Hart1, Wafik S El-Deiry

  • 1Laboratory of Molecular Oncology and Cell Cycle Regulation, Department of Medicine (Hematology/Oncology), University of Pennsylvania School of Medicine, Philadelphia, PA, 19104, USA.

Cell
|July 28, 2009
PubMed

Insights

The protein Par-4, typically acting inside cells to trigger apoptosis, can also promote programmed cell death from outside the cell. This secretion occurs after endoplasmic reticulum stress, revealing a novel extracellular role for Par-4 in cell death signaling.

Area of Science:

  • Cell biology
  • Molecular biology
  • Biochemistry

Background:

  • The protein Par-4 is known to function in the cytoplasm.
  • Par-4 initiates cell death signaling through caspase activation.
  • It also mediates the mitochondrial release of cytochrome c.

Purpose of the Study:

  • To investigate the potential extracellular functions of Par-4.
  • To explore Par-4's role in apoptosis following secretion.

Main Methods:

  • Investigated Par-4 secretion.
  • Analyzed Par-4's effect on apoptosis after secretion.
  • Studied the role of endoplasmic reticulum stress in Par-4 secretion.

Main Results:

  • Par-4 is secreted in response to endoplasmic reticulum stress.
  • Extracellular Par-4 can promote apoptosis.
  • This suggests a novel mechanism for cell death regulation.

Conclusions:

  • Par-4 has a dual role in apoptosis, acting both intracellularly and extracellularly.
  • Endoplasmic reticulum stress can trigger the secretion of Par-4.
  • Extracellular Par-4 represents a new target for modulating cell death.

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