Signaling through surface receptors in immune cells.

人类IL-5R （hIL-5R）由两条不同的多肽链，α和β组成，可激活JAK1、JAK2和STAT5。我们使用抗il - 5rα和抗β - ac单克隆抗体，通过免疫沉淀分析了il - 5rα和β - ac之间的相互作用。此外，我们还对JAK1和JAK2与每个hIL-5R亚基的结合进行了inTF-h5Ralpha评估。IL-5刺激诱导β - ac向il - 5rα募集，尽管在没有IL-5的情况下亚单位保持独立。JAK2和JAK1分别与hIL-5Ralpha和β - ac相关。IL-S刺激导致JAK2、JAK1、betac和STAT5的酪氨酸磷酸化。此外，il -5诱导的IL-5R亚基二聚化引起JAK2活化和β - ac磷酸化。此外，JAK1的酪氨酸磷酸化依赖于JAK2的激活。细胞质在346-387位置拉伸，包含富含脯氨酸的区域，是JAK2结合所必需的。这些观察结果表明，hIL-5Ralpha相关JAK2的激活对于IL-5信号事件是不可或缺的。骨髓来源的肥大细胞在钢因子（SLF）和FceRI交联以及PMA刺激下通过VLA-5 （alpha5beta1）粘附在纤维连接蛋白上。SLF和PMA交联可诱导VLA-5的扩散，但FcepsilonRI交联则不能。相反，只有FcepsilonRI交联增加了vla5的亲和力。我们还通过引入PI-3激酶的组成活性p110亚基，证明PI-3激酶是一种特定抑制剂wortmannin的关键亲和调节剂。在可溶性纤维连接蛋白存在的生理浓度下，利用亲和性或空间调节对黏附的不同影响。我们的研究结果表明，通过VLA-5的粘附受到两种生理机制的调节；通过PI 3激酶进行亲和调节，可能通过蛋白激酶C进行空间调节。

The human IL-5R (hIL-5R) consists of two distinct polypeptide chains, alpha and beta which activates JAK1 and JAK2 and STAT5. We analyzed the interaction between hIL-5Ralpha and betac by immuno-precipitation using anti-hIL-5Ralpha and anti-betac mAbs. The binding of JAK1 and JAK2 to each hIL-5R subunit was also evaluated inTF-h5Ralpha. IL-5 stimulation induced the recruitment of betac to hIL-5Ralpha, although in the absence of IL-5 the subunits remained independent. JAK2 and JAK1 were associated with hIL-5Ralpha and betac, respectively. IL-S stimulation resulted in tyrosine phosphoryl-ation of JAK2, JAK1, betac, and STAT5. Moreover, IL-5-induced dimerization of IL-5R subunits caused JAK2 activation and the betac phosphorylation. Furthermore, tyrosine phosphorylation of JAK1 depended on the activation of JAK2. The cytoplasmic stretch at position 346-387, containing the proline-rich region was necessary for JAK2 binding. These observations suggest that activation of hIL-5Ralpha associated JAK2 is indispensable for IL-5 signaling event.Bone-marrow derived mast cells adhered to fibronectin via VLA-5 (alpha5beta1) upon stimulation with steel factor (SLF) and FceRI cross-linking as well as PMA.SLF and PMA, but not FcepsilonRI cross-linking induced a diffusion of VLA-5 as well as drastic morphological changes. In contrast, only FcepsilonRI cross-linking increased affinity of VLA-5. We also showed PI 3-kinase as a critical affinity modulator by a specific inhibitor, wortmannin, and by introduction ofa constitutively active p110 subunit ofPI-3 kinase. Utilization of affinity or spatial modulation of VLA-5 caused differential effects on adhesion in the presence of physiological concentrations of soluble fibronectin. Our findings indicate that adhesion via VLA-5 are regulated physiologically by two mechanisms ; affinity modulation through PI 3-kinase and spatial modulation possibly through protein kinase C.