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Polo-like kinase 1 phosphorylates and regulates Bcl-x(L) during pironetin-induced apoptosis

Y Tamura1, S Simizu, M Muroi

  • 1Antibiotics Laboratory and Chemical Biology Department, Advanced Science Institute, RIKEN, Wako, Saitama, Japan.

Oncogene
|September 30, 2008
PubMed

Insights

Polo-like kinase 1 (Plk1) phosphorylates the anti-apoptotic protein Bcl-x(L), regulating its function. This phosphorylation is crucial for pironetin-induced apoptosis, impacting cancer chemotherapy resistance.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • Bcl-x(L) is an anti-apoptotic protein implicated in chemotherapy resistance in human tumors.
  • The phosphorylation of Bcl-x(L) following tubulin-binder treatment is known but poorly understood.
  • The specific kinases responsible for Bcl-x(L) phosphorylation remain unidentified.

Purpose of the Study:

  • To identify the kinase responsible for Bcl-x(L) phosphorylation.
  • To elucidate the role of Plk1-mediated Bcl-x(L) phosphorylation in apoptosis.
  • To understand the mechanism by which Bcl-x(L) influences resistance to specific chemotherapies.

Main Methods:

  • Immunocytochemical analyses to determine the cellular localization of Bcl-x(L) and Plk1.
  • In vitro kinase assays to confirm Plk1's ability to phosphorylate Bcl-x(L).
  • Site-directed mutagenesis to substitute identified phosphorylation sites with alanines and assess functional consequences.

Main Results:

  • Polo-like kinase 1 (Plk1) was identified as a kinase that phosphorylates Bcl-x(L).
  • Bcl-x(L) and Plk1 co-localize at the M-phase of the cell cycle.
  • Mutating Plk1 phosphorylation sites on Bcl-x(L) enhanced its anti-apoptotic activity against pironetin but not UV-induced apoptosis.

Conclusions:

  • Plk1 acts as a key regulator of Bcl-x(L) phosphorylation.
  • Plk1-mediated Bcl-x(L) phosphorylation plays a specific role in pironetin-induced apoptosis.
  • Understanding this pathway may offer insights into overcoming chemotherapy resistance in certain cancers.

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