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Non-canonical antagonism of PI3K by the kinase Itpkb delays thymocyte β-selection and renders it Notch-dependent.

Westernberg L, Conche C, Huang YH, Rigaud S, Deng Y, Siegemund S, Mukherjee S, Nosaka L, Das J, Sauer K - Elife (2016)

Bottom Line: Here, we show that this Notch-dependence is established through antagonistic signaling by the pre-TCR/Notch effector, phosphoinositide 3-kinase (PI3K), and by inositol-trisphosphate 3-kinase B (Itpkb).This is reversed by inhibition of Akt, mTOR or glucose metabolism.Thus, non-canonical PI3K-antagonism by Itpkb restricts pre-TCR induced metabolic activation to enforce coincidence-detection of pre-TCR expression and Notch-engagement.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, United States.

ABSTRACT
β-selection is the most pivotal event determining αβ T cell fate. Here, surface-expression of a pre-T cell receptor (pre-TCR) induces thymocyte metabolic activation, proliferation, survival and differentiation. Besides the pre-TCR, β-selection also requires co-stimulatory signals from Notch receptors - key cell fate determinants in eukaryotes. Here, we show that this Notch-dependence is established through antagonistic signaling by the pre-TCR/Notch effector, phosphoinositide 3-kinase (PI3K), and by inositol-trisphosphate 3-kinase B (Itpkb). Canonically, PI3K is counteracted by the lipid-phosphatases Pten and Inpp5d/SHIP-1. In contrast, Itpkb dampens pre-TCR induced PI3K/Akt signaling by producing IP4, a soluble antagonist of the Akt-activating PI3K-product PIP3. Itpkb(-/-) thymocytes are pre-TCR hyperresponsive, hyperactivate Akt, downstream mTOR and metabolism, undergo an accelerated β-selection and can develop to CD4(+)CD8(+) cells without Notch. This is reversed by inhibition of Akt, mTOR or glucose metabolism. Thus, non-canonical PI3K-antagonism by Itpkb restricts pre-TCR induced metabolic activation to enforce coincidence-detection of pre-TCR expression and Notch-engagement.

No MeSH data available.


Related in: MedlinePlus

Raw and replicate data related to Figure 5C.(A,B) HSA and combined Lin/TCRγ expression on the DN (A) and CD4-CD8+ (B) cells in Figure 5C, left panel. The HSAhighLin-TCRγ- gates in (A) were analyzed for DN cell subsets in Figure 5C, center panel. The HSAhighLin-TCRγ- gates in (B) denote ISP. ISP comprise ≥92% of CD4-CD8+ cells in E16.5 and E17.5 fetal thymi in both Itpkb+/+ and Itpkb-/- mice. (C) CD4 and CD8 expression on Itpkb+/+ or Itpkb-/- fetal thymocytes from embryos harvested on day 16.5 of embryogenesis (E16.5) from the same mother. Numbers denote % cells per gate. (D) Mean ± SEM numbers or % of DP cells in E16.5 Itpkb+/+ or Itpkb-/- fetal thymi. Significance of the indicated comparisons was analyzed as in Figure 2 (nWT = 3, nKO= 5).DOI:http://dx.doi.org/10.7554/eLife.10786.008
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fig5s1: Raw and replicate data related to Figure 5C.(A,B) HSA and combined Lin/TCRγ expression on the DN (A) and CD4-CD8+ (B) cells in Figure 5C, left panel. The HSAhighLin-TCRγ- gates in (A) were analyzed for DN cell subsets in Figure 5C, center panel. The HSAhighLin-TCRγ- gates in (B) denote ISP. ISP comprise ≥92% of CD4-CD8+ cells in E16.5 and E17.5 fetal thymi in both Itpkb+/+ and Itpkb-/- mice. (C) CD4 and CD8 expression on Itpkb+/+ or Itpkb-/- fetal thymocytes from embryos harvested on day 16.5 of embryogenesis (E16.5) from the same mother. Numbers denote % cells per gate. (D) Mean ± SEM numbers or % of DP cells in E16.5 Itpkb+/+ or Itpkb-/- fetal thymi. Significance of the indicated comparisons was analyzed as in Figure 2 (nWT = 3, nKO= 5).DOI:http://dx.doi.org/10.7554/eLife.10786.008

Mentions: Consistent with faster thymocyte development, Itpkb-/- fetal thymi had reduced overall DN and DN4 cell proportions but higher DP cell proportions and total numbers than WT controls on embryonic day 16.5 (E16.5) where DP cells are first detectable in WT mice, and on E17.5 despite 'catching up' WT DP cells (Figure 5C, Figure 5—figure supplement 1).10.7554/eLife.10786.007Figure 5.Accelerated differentiation of Itpkb-/- DN3 thymocytes.


Non-canonical antagonism of PI3K by the kinase Itpkb delays thymocyte β-selection and renders it Notch-dependent.

Westernberg L, Conche C, Huang YH, Rigaud S, Deng Y, Siegemund S, Mukherjee S, Nosaka L, Das J, Sauer K - Elife (2016)

Raw and replicate data related to Figure 5C.(A,B) HSA and combined Lin/TCRγ expression on the DN (A) and CD4-CD8+ (B) cells in Figure 5C, left panel. The HSAhighLin-TCRγ- gates in (A) were analyzed for DN cell subsets in Figure 5C, center panel. The HSAhighLin-TCRγ- gates in (B) denote ISP. ISP comprise ≥92% of CD4-CD8+ cells in E16.5 and E17.5 fetal thymi in both Itpkb+/+ and Itpkb-/- mice. (C) CD4 and CD8 expression on Itpkb+/+ or Itpkb-/- fetal thymocytes from embryos harvested on day 16.5 of embryogenesis (E16.5) from the same mother. Numbers denote % cells per gate. (D) Mean ± SEM numbers or % of DP cells in E16.5 Itpkb+/+ or Itpkb-/- fetal thymi. Significance of the indicated comparisons was analyzed as in Figure 2 (nWT = 3, nKO= 5).DOI:http://dx.doi.org/10.7554/eLife.10786.008
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4764578&req=5

fig5s1: Raw and replicate data related to Figure 5C.(A,B) HSA and combined Lin/TCRγ expression on the DN (A) and CD4-CD8+ (B) cells in Figure 5C, left panel. The HSAhighLin-TCRγ- gates in (A) were analyzed for DN cell subsets in Figure 5C, center panel. The HSAhighLin-TCRγ- gates in (B) denote ISP. ISP comprise ≥92% of CD4-CD8+ cells in E16.5 and E17.5 fetal thymi in both Itpkb+/+ and Itpkb-/- mice. (C) CD4 and CD8 expression on Itpkb+/+ or Itpkb-/- fetal thymocytes from embryos harvested on day 16.5 of embryogenesis (E16.5) from the same mother. Numbers denote % cells per gate. (D) Mean ± SEM numbers or % of DP cells in E16.5 Itpkb+/+ or Itpkb-/- fetal thymi. Significance of the indicated comparisons was analyzed as in Figure 2 (nWT = 3, nKO= 5).DOI:http://dx.doi.org/10.7554/eLife.10786.008
Mentions: Consistent with faster thymocyte development, Itpkb-/- fetal thymi had reduced overall DN and DN4 cell proportions but higher DP cell proportions and total numbers than WT controls on embryonic day 16.5 (E16.5) where DP cells are first detectable in WT mice, and on E17.5 despite 'catching up' WT DP cells (Figure 5C, Figure 5—figure supplement 1).10.7554/eLife.10786.007Figure 5.Accelerated differentiation of Itpkb-/- DN3 thymocytes.

Bottom Line: Here, we show that this Notch-dependence is established through antagonistic signaling by the pre-TCR/Notch effector, phosphoinositide 3-kinase (PI3K), and by inositol-trisphosphate 3-kinase B (Itpkb).This is reversed by inhibition of Akt, mTOR or glucose metabolism.Thus, non-canonical PI3K-antagonism by Itpkb restricts pre-TCR induced metabolic activation to enforce coincidence-detection of pre-TCR expression and Notch-engagement.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, United States.

ABSTRACT
β-selection is the most pivotal event determining αβ T cell fate. Here, surface-expression of a pre-T cell receptor (pre-TCR) induces thymocyte metabolic activation, proliferation, survival and differentiation. Besides the pre-TCR, β-selection also requires co-stimulatory signals from Notch receptors - key cell fate determinants in eukaryotes. Here, we show that this Notch-dependence is established through antagonistic signaling by the pre-TCR/Notch effector, phosphoinositide 3-kinase (PI3K), and by inositol-trisphosphate 3-kinase B (Itpkb). Canonically, PI3K is counteracted by the lipid-phosphatases Pten and Inpp5d/SHIP-1. In contrast, Itpkb dampens pre-TCR induced PI3K/Akt signaling by producing IP4, a soluble antagonist of the Akt-activating PI3K-product PIP3. Itpkb(-/-) thymocytes are pre-TCR hyperresponsive, hyperactivate Akt, downstream mTOR and metabolism, undergo an accelerated β-selection and can develop to CD4(+)CD8(+) cells without Notch. This is reversed by inhibition of Akt, mTOR or glucose metabolism. Thus, non-canonical PI3K-antagonism by Itpkb restricts pre-TCR induced metabolic activation to enforce coincidence-detection of pre-TCR expression and Notch-engagement.

No MeSH data available.


Related in: MedlinePlus