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Novel p104 protein regulates cell proliferation through PI3K inhibition and p27(Kip1) expression

Seung Jin Han1, Jung Hyun Lee, Ki Young Choi

  • 1Institute of Molecular Biology and Genetics, School of Biological Sciences, Seoul National University, Seoul 151-742, Korea.

BMB Reports
|April 2, 2010
PubMed

Insights

The protein p104 and its proline-rich region inhibit cell growth and colony formation. P104 regulates p27Kip1 levels and phosphoinositide 3-kinase activity, impacting cellular proliferation.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • The protein p104 was identified as a binding partner for the Src homology domain of phospholipase Cgamma1.
  • p104 has known associations with p85alpha and Grb2, key signaling adaptors.

Purpose of the Study:

  • To investigate the role of p104 in cellular growth regulation.
  • To elucidate the specific domains of p104 involved in its function and interactions.

Main Methods:

  • Ectopic expression of p104 and its proline-rich regions in cell lines.
  • Soft agar colony formation assays.
  • Mutagenesis analysis of p104 domains.
  • Western blotting to assess protein levels (p27Kip1) and enzyme activity assays (PI3K).

Main Results:

  • Overexpression of p104, particularly its proline-rich region, reduced cellular growth rate.
  • The proline-rich region of p104 inhibited colony formation in NIH3T3 and MCF7 cells.
  • The second and third proline-rich regions were critical for growth control and p85alpha interaction.
  • p104 overexpression elevated p27Kip1 levels and suppressed phosphoinositide 3-kinase (PI3K) activity.

Conclusions:

  • p104 interacts with p85alpha and plays a significant role in cellular proliferation control.
  • Regulation of p27Kip1 expression by p104 contributes to reduced cellular proliferation.
  • The proline-rich domain of p104 is essential for its anti-proliferative effects.

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