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LIM kinase 1 - dependent cofilin 1 pathway and actin dynamics mediate nuclear retinoid receptor function in T

Mohammad Ishaq1, Bor-Ruei Lin, Marjorie Bosche

  • 1Laboratory of Molecular Cell Biology, SAIC-Frederick, National Cancer Institute, Frederick, MD 21702, USA. mishaq@mail.nih.gov

BMC Molecular Biology
|September 20, 2011
PubMed
Abstract

Insights

Actin dynamics, regulated by the LIMK1-cofilin-1 pathway, are critical for retinoid receptor function. Disrupting actin homeostasis inhibits retinoid receptor activity, suggesting a role in T cell activation.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Immunology

Background:

  • Retinoid receptor function is known to be reduced during T cell activation.
  • Actin remodeling is involved in this process, suggesting a role for actin modification.
  • This study investigates the impact of actin dynamics on retinoid receptor activity.

Purpose of the Study:

  • To explore the role of actin dynamics in retinoid receptor-mediated transactivation.
  • To determine the effect of actin cytoskeleton modifying agents on retinoid receptor function.
  • To elucidate the involvement of the LIMK1-cofilin-1 pathway in retinoid receptor activity.

Main Methods:

  • Investigated the effects of agents that alter F-actin assembly/disassembly.
  • Utilized overexpression and siRNA knockdown of cofilin-1 (CFL1).
  • Examined the impact of CFL1 and LIMK1 mutants, including Nef protein from HIV-1.

Main Results:

  • Disturbing actin homeostasis attenuated retinoid receptor transcription.
  • CFL1 manipulation (overexpression or knockdown) led to loss of receptor function.
  • Nef protein inhibited retinoid receptor activity by altering CFL1 phosphorylation via LIMK1, disrupting actin dynamics.

Conclusions:

  • The LIMK1-mediated CFL1 pathway and actin dynamics are crucial for retinoid receptor function.
  • LIMK1-mediated CFL1 phosphocycling maintains actin homeostasis and receptor activity.
  • T cell activation may repress nuclear receptor activity partly through actin dynamics modification.

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