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Control of amino-acid transport by antigen receptors coordinates the metabolic reprogramming essential for T cell differentiation.

Sinclair LV, Rolf J, Emslie E, Shi YB, Taylor PM, Cantrell DA - Nat. Immunol. (2013)

Bottom Line: T cells responded to antigen by upregulating expression of many amino-acid transporters, but a single System L ('leucine-preferring system') transporter, Slc7a5, mediated uptake of LNAAs in activated T cells.The metabolic catastrophe caused by loss of Slc7a5 reflected the requirement for sustained uptake of the LNAA leucine for activation of the serine-threonine kinase complex mTORC1 and for expression of the transcription factor c-Myc.Control of expression of the System L transporter by pathogens is thus a critical metabolic checkpoint for T cells.

View Article: PubMed Central - PubMed

Affiliation: Division of Cell Signalling and Immunology, University of Dundee, Dundee, UK.

ABSTRACT
T lymphocytes must regulate nutrient uptake to meet the metabolic demands of an immune response. Here we show that the intracellular supply of large neutral amino acids (LNAAs) in T cells was regulated by pathogens and the T cell antigen receptor (TCR). T cells responded to antigen by upregulating expression of many amino-acid transporters, but a single System L ('leucine-preferring system') transporter, Slc7a5, mediated uptake of LNAAs in activated T cells. Slc7a5- T cells were unable to metabolically reprogram in response to antigen and did not undergo clonal expansion or effector differentiation. The metabolic catastrophe caused by loss of Slc7a5 reflected the requirement for sustained uptake of the LNAA leucine for activation of the serine-threonine kinase complex mTORC1 and for expression of the transcription factor c-Myc. Control of expression of the System L transporter by pathogens is thus a critical metabolic checkpoint for T cells.

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Activation and proliferation of Slc7a5fl/flCD4-Cre T cellsOT-I Slc7a5fl/fl and OT-IxSlc7a5fl/flCD4-Cre lymph node cells were stimulated through the TCR. (a) Cell surface expression of CD25, CD69 and CD44 on CD8+ T cells, and (b) the amount of IL-2 (left) and IFN-γ (right) produced after 20 h TCR stimulation. (c) Forward- and side-scatter profiles of CD8+ T cells after 36 h activation are shown compared to unstimulated cells maintained in IL-7 (left) and CFSE dilution (right). (d) Immunoblot analysis of total ribosomal S6 protein of CD8+ T cells after 20 h activation. (e) Slc7a5+/+ (CD45.1) and Slc7a5fl/flCD4-Cre (CD45.2) T cells were mixed at a ratio of 1:1 and adoptively transferred into Rag2−/− hosts. The graphs show percentage of recovered Slc7a5+/+ and Slc7a5fl/flCD4-Cre T cells in spleen and blood 14 days after adaptive transfer. Each data point represents data from one mouse. a, c, d data are representative of at least 3 experiments. (b)n = 3 mice per group, 1 independent experiment, triplicate samples, p=0.0019. (e) n=3 mice per group, 2 independent experiments, p<0.0001.
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Figure 6: Activation and proliferation of Slc7a5fl/flCD4-Cre T cellsOT-I Slc7a5fl/fl and OT-IxSlc7a5fl/flCD4-Cre lymph node cells were stimulated through the TCR. (a) Cell surface expression of CD25, CD69 and CD44 on CD8+ T cells, and (b) the amount of IL-2 (left) and IFN-γ (right) produced after 20 h TCR stimulation. (c) Forward- and side-scatter profiles of CD8+ T cells after 36 h activation are shown compared to unstimulated cells maintained in IL-7 (left) and CFSE dilution (right). (d) Immunoblot analysis of total ribosomal S6 protein of CD8+ T cells after 20 h activation. (e) Slc7a5+/+ (CD45.1) and Slc7a5fl/flCD4-Cre (CD45.2) T cells were mixed at a ratio of 1:1 and adoptively transferred into Rag2−/− hosts. The graphs show percentage of recovered Slc7a5+/+ and Slc7a5fl/flCD4-Cre T cells in spleen and blood 14 days after adaptive transfer. Each data point represents data from one mouse. a, c, d data are representative of at least 3 experiments. (b)n = 3 mice per group, 1 independent experiment, triplicate samples, p=0.0019. (e) n=3 mice per group, 2 independent experiments, p<0.0001.

Mentions: In vitro experiments also examined the importance of Slc7a5 expression for T cells. Slc7a5- CD8+ T cells responded to cognate antigen in vitro by increasing expression of CD69, CD44 and CD25 (Fig. 6a). They are also able to secrete normal amounts of IL-2 and produce interferon-γ, although at much lower concentrations than control TCR-activated T cells (Fig. 6b). Thus Slc7a5 is not required for the initial events of T cell activation. Flow cytometric FSC and SSC analysis of Slc7a5- T cells revealed that these cells did not undergo normal blastogenesis (Fig. 6c). Hence TCR-activated Slc7a5- T cells are much smaller than normal T lymphoblasts. In this respect, TCR-mediated activation of normal T cells induces an enhancement of ribosomal biogenesis as measured by the high expression of the S6 ribosomal subunits in TCR-activated T cells. In contrast, Slc7a5- T cells did not upregulate S6 protein (Fig. 6d). Furthermore, Slc7a5- T cells could not proliferate in response to TCR triggering in vitro. Wild-type but not Slc7a5- OT-I CD8+ T cells undergo multiple cell divisions in response to the TCR ligand SIINFEKL (Fig. 6c). We also examined the ability of Slc7a5- CD4+ and CD8+ T cells to undergo lymphopenia-induced proliferation in vivo. In these experiments control and Slc7a5- T cells were adoptively transferred at a 1:1 ratio into Rag2−/− mice. After 14 days, the recovery of control and Slc7a5- T cells from the recipient spleens showed that Slc7a5 was essential to allow both CD4+ and CD8+ T cells to undergo proliferative expansion in a lymphopenic environment (Fig. 6e). Slc7a5 is thus essential for CD4 and CD8 T cells to mediate adaptive immune responses.


Control of amino-acid transport by antigen receptors coordinates the metabolic reprogramming essential for T cell differentiation.

Sinclair LV, Rolf J, Emslie E, Shi YB, Taylor PM, Cantrell DA - Nat. Immunol. (2013)

Activation and proliferation of Slc7a5fl/flCD4-Cre T cellsOT-I Slc7a5fl/fl and OT-IxSlc7a5fl/flCD4-Cre lymph node cells were stimulated through the TCR. (a) Cell surface expression of CD25, CD69 and CD44 on CD8+ T cells, and (b) the amount of IL-2 (left) and IFN-γ (right) produced after 20 h TCR stimulation. (c) Forward- and side-scatter profiles of CD8+ T cells after 36 h activation are shown compared to unstimulated cells maintained in IL-7 (left) and CFSE dilution (right). (d) Immunoblot analysis of total ribosomal S6 protein of CD8+ T cells after 20 h activation. (e) Slc7a5+/+ (CD45.1) and Slc7a5fl/flCD4-Cre (CD45.2) T cells were mixed at a ratio of 1:1 and adoptively transferred into Rag2−/− hosts. The graphs show percentage of recovered Slc7a5+/+ and Slc7a5fl/flCD4-Cre T cells in spleen and blood 14 days after adaptive transfer. Each data point represents data from one mouse. a, c, d data are representative of at least 3 experiments. (b)n = 3 mice per group, 1 independent experiment, triplicate samples, p=0.0019. (e) n=3 mice per group, 2 independent experiments, p<0.0001.
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Figure 6: Activation and proliferation of Slc7a5fl/flCD4-Cre T cellsOT-I Slc7a5fl/fl and OT-IxSlc7a5fl/flCD4-Cre lymph node cells were stimulated through the TCR. (a) Cell surface expression of CD25, CD69 and CD44 on CD8+ T cells, and (b) the amount of IL-2 (left) and IFN-γ (right) produced after 20 h TCR stimulation. (c) Forward- and side-scatter profiles of CD8+ T cells after 36 h activation are shown compared to unstimulated cells maintained in IL-7 (left) and CFSE dilution (right). (d) Immunoblot analysis of total ribosomal S6 protein of CD8+ T cells after 20 h activation. (e) Slc7a5+/+ (CD45.1) and Slc7a5fl/flCD4-Cre (CD45.2) T cells were mixed at a ratio of 1:1 and adoptively transferred into Rag2−/− hosts. The graphs show percentage of recovered Slc7a5+/+ and Slc7a5fl/flCD4-Cre T cells in spleen and blood 14 days after adaptive transfer. Each data point represents data from one mouse. a, c, d data are representative of at least 3 experiments. (b)n = 3 mice per group, 1 independent experiment, triplicate samples, p=0.0019. (e) n=3 mice per group, 2 independent experiments, p<0.0001.
Mentions: In vitro experiments also examined the importance of Slc7a5 expression for T cells. Slc7a5- CD8+ T cells responded to cognate antigen in vitro by increasing expression of CD69, CD44 and CD25 (Fig. 6a). They are also able to secrete normal amounts of IL-2 and produce interferon-γ, although at much lower concentrations than control TCR-activated T cells (Fig. 6b). Thus Slc7a5 is not required for the initial events of T cell activation. Flow cytometric FSC and SSC analysis of Slc7a5- T cells revealed that these cells did not undergo normal blastogenesis (Fig. 6c). Hence TCR-activated Slc7a5- T cells are much smaller than normal T lymphoblasts. In this respect, TCR-mediated activation of normal T cells induces an enhancement of ribosomal biogenesis as measured by the high expression of the S6 ribosomal subunits in TCR-activated T cells. In contrast, Slc7a5- T cells did not upregulate S6 protein (Fig. 6d). Furthermore, Slc7a5- T cells could not proliferate in response to TCR triggering in vitro. Wild-type but not Slc7a5- OT-I CD8+ T cells undergo multiple cell divisions in response to the TCR ligand SIINFEKL (Fig. 6c). We also examined the ability of Slc7a5- CD4+ and CD8+ T cells to undergo lymphopenia-induced proliferation in vivo. In these experiments control and Slc7a5- T cells were adoptively transferred at a 1:1 ratio into Rag2−/− mice. After 14 days, the recovery of control and Slc7a5- T cells from the recipient spleens showed that Slc7a5 was essential to allow both CD4+ and CD8+ T cells to undergo proliferative expansion in a lymphopenic environment (Fig. 6e). Slc7a5 is thus essential for CD4 and CD8 T cells to mediate adaptive immune responses.

Bottom Line: T cells responded to antigen by upregulating expression of many amino-acid transporters, but a single System L ('leucine-preferring system') transporter, Slc7a5, mediated uptake of LNAAs in activated T cells.The metabolic catastrophe caused by loss of Slc7a5 reflected the requirement for sustained uptake of the LNAA leucine for activation of the serine-threonine kinase complex mTORC1 and for expression of the transcription factor c-Myc.Control of expression of the System L transporter by pathogens is thus a critical metabolic checkpoint for T cells.

View Article: PubMed Central - PubMed

Affiliation: Division of Cell Signalling and Immunology, University of Dundee, Dundee, UK.

ABSTRACT
T lymphocytes must regulate nutrient uptake to meet the metabolic demands of an immune response. Here we show that the intracellular supply of large neutral amino acids (LNAAs) in T cells was regulated by pathogens and the T cell antigen receptor (TCR). T cells responded to antigen by upregulating expression of many amino-acid transporters, but a single System L ('leucine-preferring system') transporter, Slc7a5, mediated uptake of LNAAs in activated T cells. Slc7a5- T cells were unable to metabolically reprogram in response to antigen and did not undergo clonal expansion or effector differentiation. The metabolic catastrophe caused by loss of Slc7a5 reflected the requirement for sustained uptake of the LNAA leucine for activation of the serine-threonine kinase complex mTORC1 and for expression of the transcription factor c-Myc. Control of expression of the System L transporter by pathogens is thus a critical metabolic checkpoint for T cells.

Show MeSH
Related in: MedlinePlus