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miR-155 Controls Lymphoproliferation in LAT Mutant Mice by Restraining T-Cell Apoptosis via SHIP-1/mTOR and PAK1/FOXO3/BIM Pathways.

Rouquette-Jazdanian AK, Kortum RL, Li W, Merrill RK, Nguyen PH, Samelson LE, Sommers CL - PLoS ONE (2015)

Bottom Line: Using miR-155-deficient, LAT mutant T cells as a discovery tool, we found two connected pathways that impact the nuclear translocation and activation of FOXO3 in T cells.This study establishes a role for PAK1 in T cell apoptosis, which contrasts to its previously identified role in T cell proliferation.Furthermore, miR-155 regulates the delicate balance between PAK1-mediated proliferation and apoptosis in T cells impacting lymphoid organ size and function.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America.

ABSTRACT
Linker for Activation of T cells (LAT) is an adapter protein that is essential for T cell function. Knock-in mice with a LAT mutation impairing calcium flux develop a fatal CD4+ lymphoproliferative disease. miR-155 is a microRNA that is correlated with hyperproliferation in a number of cancers including lymphomas and leukemias and is overexpressed in mutant LAT T cells. To test whether miR-155 was merely indicative of T cell activation or whether it contributes to lymphoproliferative disease in mutant LAT mice, we interbred LAT mutant and miR-155-deficient mice. miR-155 deficiency markedly inhibited lymphoproliferative disease by stimulating BIM-dependent CD4+ T cell apoptosis, even though ERK activation and T cell proliferation were increased in double mutant CD4+ T cells. Bim/Bcl2l11 expression is activated by the forkhead transcription factor FOXO3. Using miR-155-deficient, LAT mutant T cells as a discovery tool, we found two connected pathways that impact the nuclear translocation and activation of FOXO3 in T cells. One pathway is mediated by the inositide phosphatase SHIP-1 and the serine/threonine kinases AKT and PDK1. The other pathway involves PAK1 and JNK kinase activation. We define crosstalk between the two pathways via the kinase mTOR, which stabilizes PAK1. This study establishes a role for PAK1 in T cell apoptosis, which contrasts to its previously identified role in T cell proliferation. Furthermore, miR-155 regulates the delicate balance between PAK1-mediated proliferation and apoptosis in T cells impacting lymphoid organ size and function.

No MeSH data available.


Related in: MedlinePlus

miR-155 deficiency decreases signaling in the PI3K/mTOR pathway.Negatively selected CD4+ T cells from the indicated genotypes were stimulated with αCD3ε/CD4 (10 μg/ml, 3 min). Ages of the mice were 11 wks (WT), 10 wks (miR155-/-), 11 wks (LAT-KI), and 12 wks (DM). SDS WCLs were analyzed by WB (n = 3).
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pone.0131823.g005: miR-155 deficiency decreases signaling in the PI3K/mTOR pathway.Negatively selected CD4+ T cells from the indicated genotypes were stimulated with αCD3ε/CD4 (10 μg/ml, 3 min). Ages of the mice were 11 wks (WT), 10 wks (miR155-/-), 11 wks (LAT-KI), and 12 wks (DM). SDS WCLs were analyzed by WB (n = 3).

Mentions: We investigated SHIP-1, AKT, and PDK1 expression and phosphorylation in CD4+ T cells from miR155-deficient mice in WT and LAT-KI backgrounds (Fig 5). As expected, miR-155 deficiency resulted in increased SHIP-1 levels in both backgrounds. A consequent decrease in AKT activity as measured by AKT phosphorylation at both S473 (site of TORC2 phosphorylation) and T308 (site of PDK1 phosphorylation) [40] was observed as was phosphorylation of PDK1 (Fig 5). Basal PI3K (p85) phosphorylation was higher in LAT-KI-derived T cells than in WT-derived T cells although AKT phosphorylation was lower (Fig 5), suggesting that SHIP-1 (and not PI3K) plays a dominant role in determining AKT phosphorylation levels in LAT-KI T cells. Thus in addition to the direct effect of the loss of miR-155 on increasing FOXO3 levels, the loss of SHIP-1 repression of AKT can also have a parallel or added effect on increasing FOXO3 levels.


miR-155 Controls Lymphoproliferation in LAT Mutant Mice by Restraining T-Cell Apoptosis via SHIP-1/mTOR and PAK1/FOXO3/BIM Pathways.

Rouquette-Jazdanian AK, Kortum RL, Li W, Merrill RK, Nguyen PH, Samelson LE, Sommers CL - PLoS ONE (2015)

miR-155 deficiency decreases signaling in the PI3K/mTOR pathway.Negatively selected CD4+ T cells from the indicated genotypes were stimulated with αCD3ε/CD4 (10 μg/ml, 3 min). Ages of the mice were 11 wks (WT), 10 wks (miR155-/-), 11 wks (LAT-KI), and 12 wks (DM). SDS WCLs were analyzed by WB (n = 3).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4487994&req=5

pone.0131823.g005: miR-155 deficiency decreases signaling in the PI3K/mTOR pathway.Negatively selected CD4+ T cells from the indicated genotypes were stimulated with αCD3ε/CD4 (10 μg/ml, 3 min). Ages of the mice were 11 wks (WT), 10 wks (miR155-/-), 11 wks (LAT-KI), and 12 wks (DM). SDS WCLs were analyzed by WB (n = 3).
Mentions: We investigated SHIP-1, AKT, and PDK1 expression and phosphorylation in CD4+ T cells from miR155-deficient mice in WT and LAT-KI backgrounds (Fig 5). As expected, miR-155 deficiency resulted in increased SHIP-1 levels in both backgrounds. A consequent decrease in AKT activity as measured by AKT phosphorylation at both S473 (site of TORC2 phosphorylation) and T308 (site of PDK1 phosphorylation) [40] was observed as was phosphorylation of PDK1 (Fig 5). Basal PI3K (p85) phosphorylation was higher in LAT-KI-derived T cells than in WT-derived T cells although AKT phosphorylation was lower (Fig 5), suggesting that SHIP-1 (and not PI3K) plays a dominant role in determining AKT phosphorylation levels in LAT-KI T cells. Thus in addition to the direct effect of the loss of miR-155 on increasing FOXO3 levels, the loss of SHIP-1 repression of AKT can also have a parallel or added effect on increasing FOXO3 levels.

Bottom Line: Using miR-155-deficient, LAT mutant T cells as a discovery tool, we found two connected pathways that impact the nuclear translocation and activation of FOXO3 in T cells.This study establishes a role for PAK1 in T cell apoptosis, which contrasts to its previously identified role in T cell proliferation.Furthermore, miR-155 regulates the delicate balance between PAK1-mediated proliferation and apoptosis in T cells impacting lymphoid organ size and function.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America.

ABSTRACT
Linker for Activation of T cells (LAT) is an adapter protein that is essential for T cell function. Knock-in mice with a LAT mutation impairing calcium flux develop a fatal CD4+ lymphoproliferative disease. miR-155 is a microRNA that is correlated with hyperproliferation in a number of cancers including lymphomas and leukemias and is overexpressed in mutant LAT T cells. To test whether miR-155 was merely indicative of T cell activation or whether it contributes to lymphoproliferative disease in mutant LAT mice, we interbred LAT mutant and miR-155-deficient mice. miR-155 deficiency markedly inhibited lymphoproliferative disease by stimulating BIM-dependent CD4+ T cell apoptosis, even though ERK activation and T cell proliferation were increased in double mutant CD4+ T cells. Bim/Bcl2l11 expression is activated by the forkhead transcription factor FOXO3. Using miR-155-deficient, LAT mutant T cells as a discovery tool, we found two connected pathways that impact the nuclear translocation and activation of FOXO3 in T cells. One pathway is mediated by the inositide phosphatase SHIP-1 and the serine/threonine kinases AKT and PDK1. The other pathway involves PAK1 and JNK kinase activation. We define crosstalk between the two pathways via the kinase mTOR, which stabilizes PAK1. This study establishes a role for PAK1 in T cell apoptosis, which contrasts to its previously identified role in T cell proliferation. Furthermore, miR-155 regulates the delicate balance between PAK1-mediated proliferation and apoptosis in T cells impacting lymphoid organ size and function.

No MeSH data available.


Related in: MedlinePlus