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Tau dephosphorylation potentiates apoptosis by mechanisms involving a failed dephosphorylation/activation of Bcl-2

Xin-An Liu1, Kai Liao, Rong Liu

  • 1Department of Pathophysiology, Huazhong University of Science and Technology, Wuhan, China.

Journal of Alzheimer'S Disease : JAD
|February 17, 2010
PubMed

Insights

Tau dephosphorylation by protein phosphatase 2A catalytic subunit (PP2Ac) increases cell vulnerability to apoptosis. This occurs via impaired dephosphorylation and activation of the anti-apoptotic factor Bcl-2.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Apoptosis Research

Background:

  • Phosphorylation of tau, a key microtubule-associated protein, influences cell apoptosis.
  • The specific role of tau dephosphorylation in cell viability remains largely unknown.

Purpose of the Study:

  • To investigate the impact of tau dephosphorylation on apoptosis.
  • To elucidate the mechanisms by which tau dephosphorylation affects cell viability and Bcl-2 activity.

Main Methods:

  • Assessing cell apoptosis vulnerability under various apoptotic stimuli.
  • Examining the effects of co-expressing tau and protein phosphatase 2A catalytic subunit (PP2Ac).
  • Analyzing tau dephosphorylation, Bcl-2 phosphorylation at Ser87 (pS87-Bcl2), and apoptosis markers (cleaved PARP) using co-immunoprecipitation.

Main Results:

  • Cells with high levels of dephosphorylated tau (at Tau-1 epitope) showed increased apoptosis sensitivity.
  • Co-expression of tau and PP2Ac potentiated apoptosis, correlating with increased tau dephosphorylation and Bcl-2 phosphorylation at Ser87.
  • PP2Ac alone decreased pS87-Bcl2 and cleaved PARP levels, indicating reduced apoptosis.

Conclusions:

  • Tau dephosphorylation by PP2Ac promotes cell apoptosis.
  • The mechanism involves the failure of Bcl-2 dephosphorylation/activation, as tau binding to PP2Ac interferes with PP2Ac-Bcl-2 interaction.

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