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A positive feedback loop couples Ras activation and CD44 alternative splicing

Chonghui Cheng1, Michael B Yaffe, Phillip A Sharp

  • 1Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139, USA.

Genes & Development
|July 5, 2006
PubMed

Insights

Ras signaling and CD44 alternative splicing form a positive feedback loop crucial for cell proliferation and tumor growth. This loop sustains Ras signaling, driving cell cycle progression and mitogenesis.

Area of Science:

  • Molecular Biology
  • Cell Signaling
  • Cancer Research

Background:

  • The Ras signaling pathway regulates fundamental cellular processes like proliferation and tumor progression.
  • CD44, a cell surface glycoprotein, exists in alternatively spliced isoforms, including those with variable exon 6 (CD44v6).
  • CD44v6 can act as a coreceptor for growth factor receptors, influencing Ras activation.

Purpose of the Study:

  • To investigate the role of CD44 alternative splicing in Ras signaling.
  • To elucidate the interplay between Ras signaling and CD44v6 expression.

Main Methods:

  • Utilized v6-specific small interfering RNA (siRNA) to target CD44v6.
  • Analyzed the impact of CD44v6 modulation on Ras signaling dynamics.

Main Results:

  • Identified a positive feedback loop where Ras signaling enhances CD44v6 splicing.
  • Demonstrated that CD44v6 sustains late-phase Ras signaling.
  • Linked this feedback loop to essential cell cycle progression.

Conclusions:

  • Established a novel positive feedback mechanism connecting signaling-dependent alternative splicing to mitogenic progression.
  • Highlighted the significance of the Ras-CD44v6 axis in cell proliferation and tumor development.

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