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Development and Application of Rapamycin-regulated Tyrosine Phosphatases
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Regulation of activin/nodal signaling by Rap2-directed receptor trafficking

Sun-Cheol Choi1, Gun-Hwa Kim, Seung Joon Lee

  • 1Division of Molecular and Life Sciences, Pohang University of Science and Technology, San31, Hyoja-dong, Pohang, Kyungbuk 790-784, Korea.

Developmental Cell
|July 9, 2008
PubMed

Insights

Rap2 protein controls Activin/Nodal receptor trafficking, enhancing signaling by preventing degradation and antagonizing Smad7. This regulation is asymmetric in early embryos, influencing cell responses and embryonic patterning.

Area of Science:

  • Cell Biology
  • Developmental Biology
  • Molecular Signaling

Background:

  • Activin/Nodal signaling is crucial for embryonic development.
  • Ras GTPases regulate diverse cellular processes, including signaling pathways.
  • Receptor trafficking plays a key role in modulating signal transduction.

Purpose of the Study:

  • To investigate the role of Rap2 in Activin/Nodal signaling.
  • To elucidate how Rap2 controls Activin/Nodal receptor trafficking.
  • To understand the impact of Rap2 on embryonic patterning.

Main Methods:

  • Studied Rap2 function in Activin/Nodal signaling pathways.
  • Analyzed Activin/Nodal receptor trafficking dynamics.
  • Investigated Rap2 and Smad7 expression in Xenopus embryos.
  • Examined Smad2 activation along the dorsoventral axis.

Main Results:

  • Rap2 positively regulates Activin/Nodal signaling by controlling receptor trafficking.
  • Rap2 directs internalized receptors to recycling, preventing degradation and maintaining cell surface levels.
  • Upon ligand activation, Rap2 delays receptor turnover, upregulating signaling by antagonizing Smad7.
  • Asymmetric Rap2 and Smad7 expression in Xenopus embryos leads to differential receptor recycling efficiencies.
  • This asymmetry regulates cell responsiveness and spatiotemporal Smad2 activation, impacting embryonic patterning.

Conclusions:

  • Rap2 is a key regulator of Activin/Nodal signaling through receptor trafficking.
  • Rap2's role in receptor recycling and turnover influences signaling strength and duration.
  • Asymmetric Rap2 and Smad7 expression provides a molecular mechanism for embryonic patterning via differential signaling.
  • Findings reveal a link between receptor trafficking, signaling regulation, and developmental processes.

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