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Activated Galphaq family members induce Rho GTPase activation and Rho-dependent actin filament assembly

Parmesh Dutt1, Lars Kjoller, Maryann Giel

  • 1Physiology Department, 136 Harrison Avenue, Tufts University School of Medicine, Boston, MA 02111, USA.

FEBS Letters
|November 19, 2002
PubMed

Insights

The Galphaq protein family activates Rho GTPase signaling, which is crucial for gene transcription and actin assembly. This study clarifies Galphaq

Area of Science:

  • Cellular signaling pathways
  • Molecular biology
  • G protein-coupled receptor (GPCR) research

Background:

  • Rho GTPase is essential for actin filament assembly and serum response element (SRE)-dependent gene transcription.
  • The signaling pathways linking G protein-coupled receptors (GPCRs) to Rho activation are not fully understood.
  • While the Galpha12 family is known to induce Rho-dependent responses, the role of the Galphaq family remains controversial.

Purpose of the Study:

  • To investigate the role of the Galphaq protein family in Rho signaling pathways.
  • To determine if Galphaq activation is sufficient to induce Rho-dependent cellular responses.

Main Methods:

  • Expression of activated Galphaq members and activation of endogenous Galphaq via GPCR stimulation.
  • Measurement of SRE reporter activation and GTP-Rho levels.
  • Microinjection of activated Galphaq into fibroblasts to observe actin stress fiber formation.
  • Assessment of functional cooperation with Lbc Rho guanine nucleotide exchange factor.

Main Results:

  • Activation of Galphaq, either by expression or GPCR stimulation, leads to SRE reporter activation and increased GTP-Rho levels.
  • Microinjection of activated Galphaq induces Rho-dependent actin stress fiber formation in fibroblasts.
  • Galphaq functionally cooperates with the Lbc Rho guanine nucleotide exchange factor.

Conclusions:

  • Galphaq family signaling is sufficient to induce Rho-dependent cellular responses, including gene transcription and actin organization.
  • This study clarifies the role of Galphaq in Rho signaling, resolving conflicting previous reports.

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