mTOR Complex Signaling through the SEMA4A-Plexin B2 Axis Is Required for Optimal Activation and Differentiation of CD8+ T Cells

J Immunol. 2015 Aug 1;195(3):934-43. doi: 10.4049/jimmunol.1403038. Epub 2015 Jun 26.

Abstract

Mammalian target of rapamycin (mTOR) plays crucial roles in activation and differentiation of diverse types of immune cells. Although several lines of evidence have demonstrated the importance of mTOR-mediated signals in CD4(+) T cell responses, the involvement of mTOR in CD8(+) T cell responses is not fully understood. In this study, we show that a class IV semaphorin, SEMA4A, regulates CD8(+) T cell activation and differentiation through activation of mTOR complex (mTORC) 1. SEMA4A(-/-) CD8(+) T cells exhibited impairments in production of IFN-γ and TNF-α and induction of the effector molecules granzyme B, perforin, and FAS-L. Upon infection with OVA-expressing Listeria monocytogenes, pathogen-specific effector CD8(+) T cell responses were significantly impaired in SEMA4A(-/-) mice. Furthermore, SEMA4A(-/-) CD8(+) T cells exhibited reduced mTORC1 activity and elevated mTORC2 activity, suggesting that SEMA4A is required for optimal activation of mTORC1 in CD8(+) T cells. IFN-γ production and mTORC1 activity in SEMA4A(-/-) CD8(+) T cells were restored by administration of recombinant Sema4A protein. In addition, we show that plexin B2 is a functional receptor of SEMA4A in CD8(+) T cells. Collectively, these results not only demonstrate the role of SEMA4A in CD8(+) T cells, but also reveal a novel link between a semaphorin and mTOR signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CD8-Positive T-Lymphocytes / cytology
  • CD8-Positive T-Lymphocytes / immunology*
  • Cell Differentiation / immunology
  • Cell Proliferation
  • Fas Ligand Protein / biosynthesis
  • Granzymes / biosynthesis
  • Interferon-gamma / biosynthesis
  • Listeria monocytogenes / immunology
  • Listeriosis / immunology
  • Lymphocyte Activation / immunology*
  • Mechanistic Target of Rapamycin Complex 1
  • Mechanistic Target of Rapamycin Complex 2
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Multiprotein Complexes / immunology*
  • Multiprotein Complexes / metabolism
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / physiology*
  • Pore Forming Cytotoxic Proteins / biosynthesis
  • Protein Binding / immunology
  • RNA Interference
  • RNA, Small Interfering
  • Recombinant Proteins / genetics
  • Recombinant Proteins / pharmacology
  • Semaphorins / genetics
  • Semaphorins / physiology*
  • Signal Transduction / immunology
  • TOR Serine-Threonine Kinases / immunology*
  • TOR Serine-Threonine Kinases / metabolism
  • Tumor Necrosis Factor-alpha / biosynthesis

Substances

  • Fas Ligand Protein
  • Fasl protein, mouse
  • Multiprotein Complexes
  • Nerve Tissue Proteins
  • Plxnb2 protein, mouse
  • Pore Forming Cytotoxic Proteins
  • RNA, Small Interfering
  • Recombinant Proteins
  • Sema4A protein, mouse
  • Semaphorins
  • Tumor Necrosis Factor-alpha
  • perforin, mouse
  • Interferon-gamma
  • Mechanistic Target of Rapamycin Complex 1
  • Mechanistic Target of Rapamycin Complex 2
  • TOR Serine-Threonine Kinases
  • Granzymes
  • Gzmb protein, mouse