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Cell cycle regulated phosphorylation of the telomere-associated protein TIN2

Shuqun Yang1, Christopher M Counter

  • 1Department of Pharmacology and Cancer Biology, Department of Radiation Oncology, DUMC, Durham, North Carolina, United States of America.

Plos One
|August 27, 2013
PubMed

Insights

The study identified that the telomere protein TIN2 (TIN2) is phosphorylated at serines 295 and 330 during mitosis. This modification is linked to the mitotic kinase RSK2, suggesting a role in cell cycle regulation.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • Telomeres protect chromosome ends, and the TIN2 protein is crucial for this function within the telomere-binding complex.
  • Cell cycle-dependent phosphorylation of telomere proteins suggests potential regulatory mechanisms.
  • Investigating TIN2 phosphorylation could reveal new insights into telomere maintenance and cell cycle control.

Purpose of the Study:

  • To determine if the human TIN2 protein is modified by phosphorylation.
  • To identify specific phosphorylation sites on TIN2 and their timing within the cell cycle.
  • To elucidate the kinases responsible for TIN2 phosphorylation during mitosis.

Main Methods:

  • Phosphoproteomic analysis of human TIN2 to identify phosphorylated residues.
  • Utilized Phos-tag reagents and phosphorylation-specific antibodies to detect phosphorylation during mitosis.
  • Investigated the role of the mitotic kinase RSK2 in TIN2 phosphorylation through overexpression and inhibition studies.
  • Performed in vitro kinase assays to confirm RSK2 activity on TIN2.

Main Results:

  • Identified serines 295 and 330 as phosphorylated residues on human TIN2.
  • Confirmed that both S295 and S330 are phosphorylated specifically during mitosis.
  • Demonstrated that RSK2 kinase mediates, at least partially, the phosphorylation of TIN2 at these sites.
  • Showed increased TIN2 phosphorylation upon RSK2 expression and decreased phosphorylation with RSK inhibitor treatment.

Conclusions:

  • TIN2 undergoes specific phosphorylation at S295 and S330 during mitosis.
  • The mitotic kinase RSK2 is implicated in the phosphorylation of TIN2.
  • These findings suggest a novel mechanism for the mitotic regulation of TIN2 and telomere function through phosphorylation.

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