Inhibition of G-protein βγ signaling enhances T cell receptor-stimulated interleukin 2 transcription in CD4+ T helper cells

PLoS One. 2015 Jan 28;10(1):e0116575. doi: 10.1371/journal.pone.0116575. eCollection 2015.

Abstract

G-protein-coupled receptor (GPCR) signaling modulates the expression of cytokines that are drug targets for immune disorders. However, although GPCRs are common targets for other diseases, there are few GPCR-based pharmaceuticals for inflammation. The purpose of this study was to determine whether targeting G-protein βγ (Gβγ) complexes could provide a useful new approach for modulating interleukin 2 (IL-2) levels in CD4+ T helper cells. Gallein, a small molecule inhibitor of Gβγ, increased levels of T cell receptor (TCR)-stimulated IL-2 mRNA in primary human naïve and memory CD4+ T helper cells and in Jurkat human CD4+ leukemia T cells. Gβ1 and Gβ2 mRNA accounted for >99% of Gβ mRNA, and small interfering RNA (siRNA)-mediated silencing of Gβ1 but not Gβ2 enhanced TCR-stimulated IL-2 mRNA increases. Blocking Gβγ enhanced TCR-stimulated increases in IL-2 transcription without affecting IL-2 mRNA stability. Blocking Gβγ also enhanced TCR-stimulated increases in nuclear localization of nuclear factor of activated T cells 1 (NFAT1), NFAT transcriptional activity, and levels of intracellular Ca2+. Potentiation of IL-2 transcription required continuous Gβγ inhibition during at least two days of TCR stimulation, suggesting that induction or repression of additional signaling proteins during T cell activation and differentiation might be involved. The potentiation of TCR-stimulated IL-2 transcription that results from blocking Gβγ in CD4+ T helper cells could have applications for autoimmune diseases.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Calcium / metabolism
  • Cell Line
  • GTP-Binding Protein beta Subunits / antagonists & inhibitors
  • GTP-Binding Protein beta Subunits / metabolism*
  • GTP-Binding Protein gamma Subunits / antagonists & inhibitors
  • GTP-Binding Protein gamma Subunits / metabolism*
  • Gene Expression Regulation / drug effects
  • Gene Silencing
  • Humans
  • Interleukin-2 / genetics*
  • NFATC Transcription Factors / metabolism
  • Promoter Regions, Genetic
  • Protein Transport
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / genetics
  • Receptors, Antigen, T-Cell / metabolism*
  • Signal Transduction* / drug effects
  • T-Lymphocytes, Helper-Inducer / drug effects
  • T-Lymphocytes, Helper-Inducer / metabolism*
  • Time Factors
  • Transcription, Genetic*
  • Xanthenes / pharmacology

Substances

  • G-protein Beta gamma
  • GTP-Binding Protein beta Subunits
  • GTP-Binding Protein gamma Subunits
  • Interleukin-2
  • NFATC Transcription Factors
  • RNA, Messenger
  • RNA, Small Interfering
  • Receptors, Antigen, T-Cell
  • Xanthenes
  • gallein
  • Calcium