PDK1 regulation of mTOR and hypoxia-inducible factor 1 integrate metabolism and migration of CD8+ T cells.

mTORC1 (mammalian target of rapamycin complex 1) controls transcriptional programs that determine CD8+ cytolytic T cell (CTL) fate. In some cell systems, mTORC1 couples phosphatidylinositol-3 kinase (PI3K) and Akt to the control of glucose uptake and glycolysis. However, PI3K-Akt-independent mechanisms control glucose metabolism in CD8+ T cells, and the role of mTORC1 has not been explored. The present study now demonstrates that mTORC1 activity in CD8+ T cells is not dependent on PI3K or Akt but is critical to sustain glucose uptake and glycolysis in CD8+ T cells. We also show that PI3K- and Akt-independent pathways mediated by mTORC1 regulate the expression of HIF1 (hypoxia-inducible factor 1) transcription factor complex. This mTORC1-HIF1 pathway is required to sustain glucose metabolism and glycolysis in effector CTLs and strikingly functions to couple mTORC1 to a diverse transcriptional program that controls expression of glucose transporters, multiple rate-limiting glycolytic enzymes, cytolytic effector molecules, and essential chemokine and adhesion receptors that regulate T cell trafficking. These data reveal a fundamental mechanism linking nutrient and oxygen sensing to transcriptional control of CD8+ T cell differentiation

Phosphoproteomic analysis reveals an intrinsic pathway for the regulation of histone deacetylase 7 that controls the function of cytotoxic T lymphocytes

Here we report an unbiased analysis of the cytotoxic T lymphocyte (CTL) serine-threonine phosphoproteome by high-resolution mass spectrometry. We identified approximately 2,000 phosphorylations in CTLs, of which approximately 450 were controlled by T cell antigen receptor (TCR) signaling. A significantly overrepresented group of molecules identified included transcription activators, corepressors and chromatin regulators. A focus on chromatin regulators showed that CTLs had high expression of the histone deacetylase HDAC7 but continually phosphorylated and exported this transcriptional repressor from the nucleus. Dephosphorylation of HDAC7 resulted in its accumulation in the nucleus and suppressed expression of genes encoding key cytokines, cytokine receptors and adhesion molecules that determine CTL function. Screening of the CTL phosphoproteome has thus identified intrinsic pathways of serine-threonine phosphorylation that target chromatin regulators and determine the CTL functional program

Unique functions for protein kinase D1 and protein kinase D2 in mammalian cells

Mammalian PKD (protein kinase D) isoforms have been implicated in the regulation of diverse biological processes in response to diacylglycerol and PKC (protein kinase C) signalling. To compare the functions of PKD1 and PKD2 in vivo, we generated mice deficient in either PKD1 or PKD2 enzymatic activity, via homozygous expression of PKD1S744A/S748A or PKD2S707A/S711A ‘knockin’ alleles. We also examined PKD2-deficient mice generated using ‘gene-trap’ technology. We demonstrate that, unlike PKD1, PKD2 catalytic activity is dispensable for normal embryogenesis. We also show that PKD2 is the major PKD isoform expressed in lymphoid tissues, but that PKD2 catalytic activity is not essential for the development of mature peripheral T- and B-lymphocytes. PKD2 catalytic activity is, however, required for efficient antigen receptor-induced cytokine production in T-lymphocytes and for optimal T-cell-dependent antibody responses in vivo. Our results reveal a key in vivo role for PKD2 in regulating the function of mature peripheral lymphocytes during adaptive immune responses. They also confirm the functional importance of PKC-mediated serine phosphorylation of the PKD catalytic domain for PKD activation and downstream signalling and reveal that different PKD family members have unique and non-redundant roles in vivo

KLF2 represses CXCR3 expression and function.

<p>(A) Data show CXCR3 mRNA expression quantified by qRT-PCR in the indicated activated CD8 T cell populations normalised to GFP^neg. (B) Data show flow cytometric analysis of CXCR3 surface expression and GFP expression in GFP^pos or GFP-KLF2^pos activated CD8 T cells. (C) GFP-KLF2^neg and GFP-KLF2^pos activated CD8 T cells were competitively assayed for their ability to migrate to CXCL10. Data shown are the percentage of cells migrating (relative to input controls) at the given CXCL10 concentrations. (D) MFI of CXCR3 quantified by flow cytometry in naïve OT-1 CD8 T cells activated with N4, Q4, Q4R7 or Q4H7 for 24 hours. (E) CXCR3 expression measured by flow cytometry in naïve OT-1 CD8 T cells incubated with N4 peptide and PD184352 for 24 hours as indicated. Data in A, C & D show mean + SEM of 3 independent experiments. Data in B and E representative of 3 independent experiments.</p

KLF2 expression is regulated by the strength and duration of TCR and cytokine stimulation.

<p>(A) Data show relative KLF2 mRNA expression quantified by qRT-PCR in purified naïve CD8 T cells incubated with gp33-41 peptide for the times shown. Results are normalised to untreated naïve cells. (B) KLF2 mRNA in purified naïve OT-1 CD8 T cells incubated with SIIQFEHL (Q4H7) or SIIQFERL (Q4R7), SIIQFEKL (Q4) or SIINFEKL (N4) peptide for 4 hours. Results are normalised to untreated naïve cells. (C) CD62L and S1P1 mRNA in purified naïve OT-1 CD8 T cells incubated with Q4H7, Q4R7, Q4 or N4 peptide for 4 hours. Results are normalised to untreated naïve cells. (D) KLF2 mRNA (normalised to time 0 sample) in T cells activated with gp33-41 peptide for 2 days, cultured in IL-2 for 5 days and then cultured without cytokine for the times shown. (E) KLF2 mRNA (normalised to CTL cultured with 20ng/ml IL-2) in T cells activated with gp33-41 peptide for 2 days, cultured in IL-2 for 5 days and then cultured with the indicated concentrations of IL-2 for 18 hours. All data show mean + SEM of at least 3 independent experiments.</p

Low KLF2 expression can control trafficking molecules but high KLF2 expression is required to inhibit proliferation.

<p>(A) Data show the gating strategy used to identify populations with differential KLF2 expression in GFP-KLF2 transduced activated CD8 T cells. For all experiments P14 CD8 T cells were activated for with gp33-41 peptide and retroviral transduction was performed 18 hours after activation. At 48 hours after the initial activation cells were washed and cultured for a further 3 days with 20ng/ml IL-2. (B) Population expression of CD62L measured by flow cytometry in GFP^pos, GFP-KLF2^low and GFP-KLF2^high activated CD8 T cells. (C) CD62L median fluorescence intensities (MFIs) in CD8 T cell populations as indicated. (D) Inhibition of DNA synthesis relative to control GFP-KLF2^neg CD8 T cells was quantified for GFP-KLF2^low, GFP-KLF2^mid and GFP-KLF2^high CD8 T cells (data show mean + SEM of 3 independent experiments). (E) CXCR3 MFIs in indicated CD8 T cells populations. Data shown in C & E are the mean + SEM of MFIs normalised to GFP^neg population from 3 independent experiments.</p

MEK1 and PI3K/PKB activity are required for maximal TCR mediated downregulation of KLF2.

<p>(A) Schematic diagram of KLF2 gene indicating binding sites of primers used. (B) Data show binding of RNA polymerase II to the indicated site in the KLF2 gene measured by ChIP assay. Black bars indicate binding in purified naïve OT-1 CD8 T cells, grey bars indicate OT-1 CD8 T cells stimulated with N4 peptide for 6 hours. (C) Spliced and unspliced KLF2 mRNA in purified naïve OT-1 CD8 T cells incubated with Q4H7, Q4R7, Q4 or N4 peptide for 4 hours. Results are normalised to untreated naïve cells. (D) Western blot of lysates from purified naïve OT-1 CD8 T cells incubated with N4 peptide and inhibitors for 4 hours as indicated. (E) KLF2 mRNA in purified naïve P14 CD8 T cells incubated with gp33-41 peptide and inhibitors for 4 hours as indicated. (F) KLF2, CD62L and S1P1 mRNA in FACS purified GFP positive P14 CD8 T cells transduced with control or FoxO3AAA constructs as shown and treated or not with gp33-41 peptide for 4 hours as indicated. (G) CD62L, spliced and unspliced KLF2 mRNA in purified naïve P14 CD8 T cells incubated with gp33 peptide and inhibitors as indicated for 4 hours. Results for each mRNA are normalised to that particular mRNA level in untreated naïve cells – note that comparison of the amount of unspliced or spliced RNA cannot be made. Data in B, C, E, F and G show mean + SEM of at least 3 independent experiments. Data in D are representative of 3 independent experiments.</p

KLF2 re-expression inhibits proliferation but not via <i>c-myc</i> repression.

<p>(A) Data show the cellular DNA content of GFP-KLF2^neg and GFP-KLF2^pos activated CD8 T cells. Data are representative of 4 independent experiments. (B) Expression of <i>c-myc</i> mRNA in FACS purified activated CD8 T cells quantified by qRT-PCR (data normalised to GFP^neg and show mean + SEM of 3 independent experiments). (C) DNA synthesis measured by EdU uptake in the T cell populations shown (data show mean percentage EdU uptake + SEM, n=3). (D) Cell counts of GFP^pos and KLF2^pos activated CD8 T cells; data shown are mean ± SEM of 3 independent experiments. </p

Rapamycin treatment controls trafficking molecules but not DNA synthesis in activated CD8 T cells.

<p>(A) Data show expression of KLF2 mRNA determined by qRT-PCR in purified naïve CD8 T cells and T cells activated with gp33-41 peptide for 2 days then cultured with IL-2 plus DMSO or 20nM rapamycin for 5 days. Data are normalised to expression in control T cells and show mean + SEM of 3 independent experiments. (B) CD62L surface expression in CD8 T cells treated as in (A) measured by flow cytometry (data representative of 5 independent experiments). (C) CXCR3 mRNA in CD8 T cells treated as in (A) quantified by qRT-PCR. Data normalised to control T cells and show mean + SEM of 3 independent experiments. (D) CXCR3 surface expression in activated CD8 T cells treated as in (A) measured by flow cytometry, data representative of 3 independent experiments. (E) DNA synthesis measured by EdU uptake in T cells activated with gp33-41 peptide for 2 days then cultured with IL-2 plus either DMSO or rapamycin for 2 days. Data show mean percentage EdU uptake + SEM of 3 independent experiments.</p