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MEKK3 regulates IFN-gamma production in T cells through the Rac1/2-dependent MAPK cascades

Xiaofang Wang1,2,3, Fan Zhang1,2,4, Fanping Chen4

  • 1Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520.

Journal of Immunology (Baltimore, Md. : 1950)
|April 8, 2011
PubMed

Insights

Mitogen-activated protein kinase kinase kinase 3 (MEKK3) is crucial for T cell immunity. MEKK3 deficiency impairs T cell responses and IFN-γ production, highlighting its role in adaptive immunity signaling.

Area of Science:

  • Immunology
  • Cellular signaling
  • Molecular biology

Background:

  • MEKK3 (MAP3K) is a protein kinase expressed in T cells.
  • Its precise role in T cell immunity remains unclear.
  • Understanding MEKK3 function is vital for T cell-mediated immunity.

Purpose of the Study:

  • To investigate the role of MEKK3 in T cell immunity in vivo.
  • To elucidate the signaling pathways regulated by MEKK3 in T cells.
  • To determine MEKK3's contribution to cytokine production and T cell responses.

Main Methods:

  • Utilized Mekk3 T cell conditional knockout (T-cKO) mice.
  • Assessed T cell responses to bacterial infection in vivo.
  • Analyzed antigen-induced cytokine production (IFN-γ) in vitro.
  • Investigated T cell receptor (TCR)-induced MAPK activation (ERK1/2, JNK, p38).
  • Examined Th1/Th2 differentiation and IFN-γ production under nonpolarizing conditions.
  • Studied IL-12/IL-18-driven IFN-γ production and MAPK activation.
  • Investigated MEKK3 activation requirements (Rac1/2).

Main Results:

  • Mekk3 T-cKO mice exhibited reduced T cell responses and impaired bacterial clearance.
  • MEKK3-deficient CD4 T cells showed defective antigen-induced IFN-γ production.
  • TCR-induced activation of ERK1/2, JNK, and p38 MAPKs was impaired in Mekk3-deficient CD4 T cells.
  • MEKK3 deficiency did not affect Th1/Th2 differentiation but reduced IFN-γ production under Th0 conditions.
  • IL-12/IL-18-driven IFN-γ production and MAPK activation were unaffected by Mekk3 deficiency.
  • MEKK3 activation by TCR stimulation depends on Rac1/2.

Conclusions:

  • MEKK3 is essential for effective T cell immunity in vivo.
  • MEKK3 selectively mediates TCR-induced MAPK signaling pathways critical for IFN-γ production.
  • MEKK3 plays a specific role in adaptive immune responses, particularly in IFN-γ regulation.

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