ABSTRACT
The phosphatase Shp-2 was implicated in NK cell development and functions due to its interaction with NK inhibitory receptors, but its exact role in NK cells is still unclear. Here we show, using mice conditionally deficient for Shp-2 in the NK lineage, that NK cell development and responsiveness are largely unaffected. Instead, we find that Shp-2 serves mainly to enforce NK cell responses to activation by IL-15 and IL-2. Shp-2-deficient NK cells have reduced proliferation and survival when treated with high dose IL-15 or IL-2. Mechanistically, Shp-2 deficiency hampers acute IL-15 stimulation-induced raise in glycolytic and respiration rates, and causes a dramatic defect in ERK activation. Moreover, inhibition of the ERK and mTOR cascades largely phenocopies the defect observed in the absence of Shp-2. Together, our data reveal a critical function of Shp-2 as a molecular nexus bridging acute IL-15 signaling with downstream metabolic burst and NK cell expansion.
Subject(s)
Extracellular Signal-Regulated MAP Kinases/metabolism , Killer Cells, Natural/metabolism , Protein Tyrosine Phosphatase, Non-Receptor Type 11/metabolism , Receptors, Interleukin-15/metabolism , Animals , Antigens, Ly/metabolism , Cell Count , Cell Proliferation/drug effects , Cell Size/drug effects , Enzyme Activation/drug effects , Integrases/metabolism , Interleukin-15/pharmacology , Killer Cells, Natural/drug effects , Mice, Inbred C57BL , Mice, Knockout , Muromegalovirus/physiology , Natural Cytotoxicity Triggering Receptor 1/metabolism , Protein Tyrosine Phosphatase, Non-Receptor Type 11/deficiency , TOR Serine-Threonine Kinases/metabolismABSTRACT
Interleukin-3 (IL-3) and stem cell factor (SCF) are important mast cell growth and differentiation factors. Since both cytokines activate the transcription factor signal transducer and activator of transcription 5 (Stat5), a known regulator of proliferation and survival, we investigated the effects of Stat5 deficiency on mast cell development and survival. Bone marrow-derived mast cell (BMMC) populations cultured from Stat5A/B-deficient mice survived in IL-3 + SCF, but not in either cytokine alone. These cells demonstrated reduced expression of Bcl-2, Bcl-x(L), cyclin A2, and cyclin B1, with increased apoptosis and delayed cell cycle progression during IL-3 or SCF culture. Finally, the absence of Stat5 resulted in loss of in vivo mast cell development, as judged by assessments of Stat5-deficient mice and transplantation of Stat5-deficient bone marrow cells to mast cell-deficient recipient mice. These results indicate that Stat5A and Stat5B are critical regulators of in vitro and in vivo mast cell development and survival.
Subject(s)
DNA-Binding Proteins/physiology , Mast Cells/cytology , Milk Proteins , Trans-Activators/physiology , Animals , Caspases/metabolism , Cells, Cultured , Cyclins/biosynthesis , Cyclins/genetics , DNA-Binding Proteins/biosynthesis , DNA-Binding Proteins/deficiency , Enzyme Activation/genetics , Humans , Interleukin-3/pharmacology , Mast Cells/physiology , Mice , Mice, Inbred C57BL , Mitochondria/physiology , Proto-Oncogene Proteins c-bcl-2/biosynthesis , Recombinant Proteins/pharmacology , STAT5 Transcription Factor , Signal Transduction/drug effects , Signal Transduction/physiology , Stem Cell Factor/pharmacology , Trans-Activators/biosynthesis , Trans-Activators/deficiency , Tumor Suppressor Proteins , Up-RegulationABSTRACT
Interleukin-3 (IL-3) and stem cell factor (SCF) are important mast cell growth and differentiation factors. Since both cytokines activate the transcription factor Stat5, a known regulator of proliferation and survival, we investigated the effects of Stat5 deficiency on mast cell development and survival. This article will review data presented at The Fourth International Workshop on Signal Transduction in the Activation and Development of Mast Cells and Basophils. The full set of data is now in preparation for publication. We find that the absence of Stat5 A and B results in a total loss of in vivo mast cell development. Bone marrow-derived mast cell (BMMC) populations can be cultured and maintained from Stat5-deficient mice in IL-3+SCF, but not in either cytokine alone. The absence of Stat5 resulted in aberrant control of Bcl-2, Bcl-x(L) and cyclin A2, with increased apoptosis and delayed cell cycle progression after IL-3 or SCF stimulation. These results indicate that Stat5 A and B are critical regulators of in vitro and in vivo mast cell biology.
