Regulation Of The Immune Response By The Inositol Phosphatase SHIP

在SHIP缺失小鼠中观察到淋巴细胞异常，但尚不清楚它们是由于这些细胞中SHIP的内在要求还是严重骨髓病理学的结果。 为了精确地解决SHIP在T细胞中的功能，我们已经产生了具有T细胞特异性SHIP缺失的小鼠。 在没有SHIP的情况下，我们发现胸腺选择或外周调节性T细胞的活化状态和数量没有差异。 相反，SHIP缺陷型T细胞在体外不能有效地偏向于Th 2。 具有SHIP的T细胞特异性缺失的小鼠在明矾/NP-CGG免疫后显示出较差的抗体应答，并且当用曼氏血吸虫卵攻击时显示出减少的Th 2细胞因子产生。 未能偏向于Th 2应答可能是Th 1相关转录因子T-bet的基础水平增加的结果，这是由于对苦参碱介导的T-bet诱导的敏感性增强所致。 SHIP缺陷型CD 8+细胞显示增强的细胞毒性应答，与这些细胞中升高的T-bet水平一致。 总体而言，我们的实验表明，在T细胞中，SHIP负调控甘氨酸介导的激活的方式，允许有效的Th 2应答和限制T细胞的细胞毒性。 肥大细胞上高亲和力IgE受体（Fc-IgE-RI）的聚集启动导致脱粒和细胞因子释放的信号传导途径。已有报道SHIP-1负调控Fc-γ-RI触发的通路，但其同源蛋白SHIP-2是否具有相同的功能尚不清楚。 我们已经使用基于慢病毒的RNA干扰技术获得SHIP-2敲低的骨髓源性肥大细胞（BMMC），并且已经发现，在Fc-γ-RI刺激后，SHIP-2的消除导致肥大细胞脱粒和细胞因子（IL-4和IL-13）基因表达增加。 从BMMC中消除SHIP-2对Fc γ-受体抑制剂触发的钙流、MAPK的酪氨酸磷酸化或激活后的肌动蛋白解聚没有影响。 相反，我们观察到SHIP-2的缺乏导致小GTdR Rac-1的活化增加，并且在Fc-Rac-RI接合后增强微管聚合。大鼠嗜碱性白血病（RBL 2 H3）细胞中的免疫共沉淀实验显示SHIP-2与FcRI -链、Gab 2和林恩相互作用，并且与SHIP-1不同，它不与肥大细胞中的SHC相关。我们的研究结果报告了负调节作用的船舶-2肥大细胞的活化，是钙的独立性和不同的监管船舶-1。

Lymphocyte anomalies have been observed in SHIP-null mice but it is unclear whether they are due to an intrinsic requirement of SHIP in these cells or a consequence of the severe myeloid pathology. To precisely address the function of SHIP in T cells we have generated mice with T cell-specific deletion of SHIP. In the absence of SHIP, we found no differences in thymic selection or in the activation state and numbers of regulatory T cells in the periphery. In contrast, SHIP-deficient T cells do not skew efficiently to Th2 in vitro. Mice with T cell-specific deletion of SHIP show poor antibody responses upon Alum/NP-CGG immunization and diminished Th2 cytokine production when challenged with Schistosoma mansoni eggs. The failure to skew to Th2 responses may be the consequence of increased basal levels of the Th1-associated transcriptional factor T-bet, resulting from enhanced sensitivity to cytokine-mediated T-bet induction. SHIP-deficient CD8+ cells show enhanced cytotoxic responses, consistent with elevated T-bet levels in these cells. Overall our experiments indicate that in T cells, SHIP negatively regulates cytokine-mediated activation in a way that allows effective Th2 responses and limits T cell cytotoxicity. Aggregation of the high affinity IgE receptor (Fc-epsilon-RI) on mast cells initiates signaling pathways leading to degranulation and cytokine release. It has been reported that SHIP-1 negatively regulates Fc-epsilon-RI-triggered pathways but it is unknown whether its homologous protein SHIP-2 has the same function. We have used a lentiviral based RNA interference technique to obtain SHIP-2 knockdown bone marrow-derived mast cells (BMMCs) and have found that elimination of SHIP-2 results in both increased mast cell degranulation and cytokine (IL-4 and IL-13) gene expression upon Fc-epsilon-RI stimulation. Elimination of SHIP-2 from BMMCs has no effect on Fc epsilon RI-triggered calcium flux, tyrosine phosphorylation of MAPKs or in actin depolymerization following activation. Rather, we observe that absence of SHIP-2 results in increased activation of the small GTPase Rac-1 and in enhanced microtubule polymerization upon Fc-epsilon-RI engagement. Co-immunoprecipitation experiments in rat basophilic leukemia (RBL 2H3) cells show that SHIP-2 interacts with the FcRI -chain, Gab2 and Lyn and that unlike SHIP-1, it does not associate with SHC in mast cells. Our results report a negative regulatory role of SHIP-2 on mast cell activation that is calcium independent and distinct from the regulation by SHIP-1.