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14-3-3 mediated regulation of the tumor suppressor protein, RASSF1A

Haya Abu Ghazaleh1, Renfred S Chow, Sheryl L Choo

  • 1Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2N8, Canada.

Apoptosis : an International Journal on Programmed Cell Death
|January 14, 2010
PubMed

Insights

Ras association domain family protein 1A (RASSF1A) tumor suppressor function in apoptosis is regulated by 14-3-3 protein binding. Loss of this binding initiates RASSF1A-mediated cell death, revealing a key control mechanism.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • Death receptor-mediated apoptosis is crucial for controlling cell growth.
  • Ras association domain family protein 1A (RASSF1A) acts as a tumor suppressor in this process.
  • The precise initiation mechanism of RASSF1A-mediated cell death remained unclear.

Purpose of the Study:

  • To elucidate the role of 14-3-3 proteins in regulating RASSF1A-mediated apoptosis.
  • To identify the specific interactions and signaling events involved in RASSF1A-mediated cell death initiation.
  • To investigate the impact of RASSF1A phosphorylation on its interaction with 14-3-3 and subsequent cell death.

Main Methods:

  • Utilized tumor necrosis factor alpha (TNFα) and TNFα-related apoptosis-inducing ligand (TRAIL) stimulation to trigger apoptosis.
  • Investigated protein-protein interactions using co-immunoprecipitation assays.
  • Employed site-directed mutagenesis to alter phosphorylation sites on RASSF1A.
  • Assessed cell death markers, including Annexin V staining and poly (ADP-ribose) polymerase (PARP) cleavage.

Main Results:

  • Basal association of RASSF1A with 14-3-3 proteins was disrupted upon TNFα or TRAIL stimulation.
  • Disruption of 14-3-3 binding led to RASSF1A association with modulator of apoptosis 1 (MOAP-1) and death receptors (TNF-R1/TRAIL-R1).
  • Phosphorylation of RASSF1A by glycogen synthase kinase 3β (GSK-3β) at serine residues 175, 178, and 179 is essential for 14-3-3 binding.
  • Mutating these serine residues resulted in premature RASSF1A recruitment to MOAP-1 and death receptors, and increased basal cell death and apoptosis markers upon TNFα stimulation.

Conclusions:

  • 14-3-3 proteins act as critical negative regulators of RASSF1A-mediated apoptosis.
  • The phosphorylation status of RASSF1A dictates its interaction with 14-3-3 proteins, thereby controlling the initiation of cell death.
  • This study reveals a novel regulatory mechanism for RASSF1A-mediated cell death, highlighting the importance of 14-3-3 binding in tumor suppression.

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