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Updated: May 12, 2026

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
10:27

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells

Published on: March 9, 2012

Small GTPase Rap1 regulates cell migration through regulation of small GTPase RhoA activity in response to

Mi-Young Moon1, Hee-Jun Kim, Jae-Gyu Kim

  • 1Department of Biochemistry, College of Medicine, Hallym University, Chuncheon, Kangwon-Do, Republic of Korea.

Journal of Cellular Physiology
|April 6, 2013
PubMed

Insights

Transforming growth factor-beta 1 (TGF-β1) suppresses macrophage migration late in inflammation. This occurs via a cAMP-Epac-Rap1-ARAP3 pathway that inhibits RhoA activity and chemokine production.

Area of Science:

  • Cellular Biology
  • Immunology
  • Molecular Biology

Background:

  • Transforming growth factor-beta 1 (TGF-β1) has dual roles in monocyte migration, initially promoting and later inhibiting it.
  • Understanding the mechanisms behind TGF-β1's inhibitory effect on late-phase cell migration is crucial.

Purpose of the Study:

  • To elucidate the molecular mechanism by which TGF-β1 suppresses macrophage migration in the late phase.
  • To investigate the roles of RhoA, Rap1, and associated signaling molecules in TGF-β1-mediated migration inhibition.

Main Methods:

  • Utilized Raw 264.7 cells and employed techniques such as small interfering RNA (siRNA) for gene knockdown (sh-RhoA, si-Rap1, si-Epac1/2, si-ARAP3).
  • Measured chemokine production (MIP-1α) and GTP-bound RhoA and Rap1 levels.
  • Administered TGF-β1 and Epac activator (8CPT-2Me-cAMP) to assess their effects on cellular signaling and migration.

Main Results:

  • Short TGF-β1 exposure induced macrophage inflammatory protein (MIP)-1α production and migration, dependent on RhoA.
  • Prolonged TGF-β1 exposure led to increased cAMP, activating Epac, Rap1, and ARAP3, which suppressed RhoA activity.
  • Rap1 activation, contrary to common belief, inhibited macrophage migration by suppressing RhoA, mediated by Epac and ARAP3.

Conclusions:

  • A novel pathway involving cAMP-Epac-Rap1-ARAP3 mediates TGF-β1-induced suppression of macrophage migration.
  • Rap1's role in inhibiting cell migration via RhoA suppression is demonstrated, challenging existing paradigms.
  • This finding provides new insights into the regulation of inflammatory cell migration by TGF-β1.

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