CCL5-mediated T-cell chemotaxis involves the initiation of mRNA translation through mTOR/4E-BP1

Blood. 2008 May 15;111(10):4892-901. doi: 10.1182/blood-2007-11-125039. Epub 2008 Mar 12.

Abstract

The multistep, coordinated process of T-cell chemotaxis requires chemokines, and their chemokine receptors, to invoke signaling events to direct cell migration. Here, we examined the role for CCL5-mediated initiation of mRNA translation in CD4(+) T-cell chemotaxis. Using rapamycin, an inhibitor of mTOR, our data show the importance of mTOR in CCL5-mediated T-cell migration. Cycloheximide, but not actinomycin D, significantly reduced chemotaxis, suggesting a possible role for mRNA translation in T-cell migration. CCL5 induced phosphorylation/activation of mTOR, p70 S6K1, and ribosomal protein S6. In addition, CCL5 induced PI-3'K-, phospholipase D (PLD)-, and mTOR-dependent phosphorylation and deactivation of the transcriptional repressor 4E-BP1, which resulted in its dissociation from the eukaryotic initiation factor-4E (eIF4E). Subsequently, eIF4E associated with scaffold protein eIF4G, forming the eIF4F translation initiation complex. Indeed, CCL5 initiated active translation of mRNA, shown by the increased presence of high-molecular-weight polysomes that were significantly reduced by rapamycin treatment. Notably, CCL5 induced protein translation of cyclin D1 and MMP-9, known mediators of migration. Taken together, we describe a novel mechanism by which CCL5 influences translation of rapamycin-sensitive mRNAs and "primes" CD4(+) T cells for efficient chemotaxis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism*
  • Cell Cycle Proteins
  • Cells, Cultured
  • Chemokine CCL5 / physiology*
  • Chemotaxis, Leukocyte*
  • Cyclin D1 / biosynthesis
  • Humans
  • Matrix Metalloproteinase 9 / biosynthesis
  • Mechanistic Target of Rapamycin Complex 1
  • Multiprotein Complexes
  • Phosphoproteins / metabolism*
  • Protein Biosynthesis*
  • Proteins
  • T-Lymphocytes / cytology
  • T-Lymphocytes / physiology*
  • TOR Serine-Threonine Kinases
  • Transcription Factors / metabolism*

Substances

  • Adaptor Proteins, Signal Transducing
  • Cell Cycle Proteins
  • Chemokine CCL5
  • EIF4EBP1 protein, human
  • Multiprotein Complexes
  • Phosphoproteins
  • Proteins
  • Transcription Factors
  • Cyclin D1
  • Mechanistic Target of Rapamycin Complex 1
  • TOR Serine-Threonine Kinases
  • Matrix Metalloproteinase 9