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Ral-Arf6 crosstalk regulates Ral dependent exocyst trafficking and anchorage independent growth signalling

Archana Pawar1, Jeremy A Meier2, Anwesha Dasgupta1

  • 1Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411 008, Maharashtra, India.

Cellular Signalling
|June 9, 2016
PubMed

Insights

This study reveals a new link between Ral and Arf6 GTPases, crucial for cell adhesion and cancer growth. This Ral-Arf6 interaction controls cell signaling pathways essential for anchorage-independent growth in cancer.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Cancer Research

Background:

  • Integrin-mediated signaling regulates anchorage dependence, a process often disrupted in cancer.
  • The small GTPase Ral is a key mediator of adhesion-dependent trafficking and signaling downstream of integrins and oncogenic Ras.
  • Understanding Ral's regulatory mechanisms is vital for cancer therapy development.

Purpose of the Study:

  • To identify novel regulatory crosstalk involving the small GTPase Ral.
  • To elucidate the role of this crosstalk in adhesion-dependent and anchorage-independent cell signaling.
  • To determine the significance of this pathway in both normal and cancer cells.

Main Methods:

  • Utilized mouse fibroblasts (MEFs) and human bladder cancer T24 cells.
  • Investigated integrin-dependent and constitutive activation of Ral isoforms (RalA, RalB).
  • Analyzed the activation of Arf6 and its downstream effects on cell signaling pathways, including Erk signaling.

Main Results:

  • Identified a novel regulatory crosstalk between Ral and Arf6, where integrin-dependent RalA activation drives Arf6 activation in MEFs.
  • Demonstrated that constitutively active RalA and RalB can activate Arf6 independently of cell adhesion.
  • Showed that the Ral-Arf6 pathway mediates the delivery of raft microdomains to the plasma membrane, supporting anchorage-independent growth and Erk signaling in T24 cancer cells.

Conclusions:

  • Arf6 acts as a key downstream mediator of Ral isoform function in adhesion-dependent pathways.
  • The identified Ral-Arf6 crosstalk is crucial for anchorage-independent growth signaling in cancer.
  • This pathway represents a potential therapeutic target for cancers with deregulated adhesion signaling.
Keywords:
AdhesionAnchorage independenceArf6CancerExocyst traffickingRal

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