Ahmad F, Gao G, Wang L M, Landstrom T R, Degerman E, Pierce J H, Manganiello V C
Pulmonary/Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, Bethesda, MD 20892, USA.
J Immunol. 1999 Apr 15;162(8):4864-75.
In FDCP2 myeloid cells, IL-4 activated cyclic nucleotide phosphodiesterases PDE3 and PDE4, whereas IL-3, granulocyte-macrophage CSF (GM-CSF), and phorbol ester (PMA) selectively activated PDE4. IL-4 (not IL-3 or GM-CSF) induced tyrosine phosphorylation of insulin-receptor substrate-2 (IRS-2) and its association with phosphatidylinositol 3-kinase (PI3-K). TNF-alpha, AG-490 (Janus kinase inhibitor), and wortmannin (PI3-K inhibitor) inhibited activation of PDE3 and PDE4 by IL-4. TNF-alpha also blocked IL-4-induced tyrosine phosphorylation of IRS-2, but not of STAT6. AG-490 and wortmannin, not TNF-alpha, inhibited activation of PDE4 by IL-3. These results suggested that IL-4-induced activation of PDE3 and PDE4 was downstream of IRS-2/PI3-K, not STAT6, and that inhibition of tyrosine phosphorylation of IRS molecules might be one mechnism whereby TNF-alpha could selectively regulate activities of cytokines that utilized IRS proteins as signal transducers. RO31-7549 (protein kinase C (PKC) inhibitor) inhibited activation of PDE4 by PMA. IL-4, IL-3, and GM-CSF activated mitogen-activated protein (MAP) kinase and protein kinase B via PI3-K signals; PMA activated only MAP kinase via PKC signals. The MAP kinase kinase (MEK-1) inhibitor PD98059 inhibited IL-4-, IL-3-, and PMA-induced activation of MAP kinase and PDE4, but not IL-4-induced activation of PDE3. In FDCP2 cells transfected with constitutively activated MEK, MAP kinase and PDE4, not PDE3, were activated. Thus, in FDCP2 cells, PDE4 can be activated by overlapping MAP kinase-dependent pathways involving PI3-K (IL-4, IL-3, GM-CSF) or PKC (PMA), but selective activation of PDE3 by IL-4 is MAP kinase independent (but perhaps IRS-2/PI3-K dependent).
在FDCP2髓样细胞中，白细胞介素-4（IL-4）激活环核苷酸磷酸二酯酶PDE3和PDE4，而白细胞介素-3（IL-3）、粒细胞-巨噬细胞集落刺激因子（GM-CSF）和佛波酯（PMA）则选择性激活PDE4。IL-4（而非IL-3或GM-CSF）诱导胰岛素受体底物-2（IRS-2）的酪氨酸磷酸化及其与磷脂酰肌醇3激酶（PI3-K）的结合。肿瘤坏死因子-α（TNF-α）、AG-490（Janus激酶抑制剂）和渥曼青霉素（PI3-K抑制剂）抑制IL-4对PDE3和PDE4的激活。TNF-α也阻断IL-4诱导的IRS-2酪氨酸磷酸化，但不阻断信号转导和转录激活因子6（STAT6）的酪氨酸磷酸化。AG-490和渥曼青霉素而非TNF-α抑制IL-3对PDE4的激活。这些结果表明，IL-4诱导的PDE3和PDE4激活位于IRS-2/PI3-K下游，而非STAT6下游，并且抑制IRS分子的酪氨酸磷酸化可能是TNF-α选择性调节利用IRS蛋白作为信号转导分子的细胞因子活性的一种机制。RO31-7549（蛋白激酶C（PKC）抑制剂）抑制PMA对PDE4的激活。IL-4、IL-3和GM-CSF通过PI3-K信号激活丝裂原活化蛋白（MAP）激酶和蛋白激酶B；PMA仅通过PKC信号激活MAP激酶。MAP激酶激酶（MEK-1）抑制剂PD98059抑制IL-4、IL-3和PMA诱导的MAP激酶和PDE4激活，但不抑制IL-4诱导的PDE3激活。在转染组成型激活MEK的FDCP2细胞中，MAP激酶和PDE4而非PDE3被激活。因此，在FDCP2细胞中，PDE4可通过涉及PI3-K（IL-4、IL-3、GM-CSF）或PKC（PMA）的重叠MAP激酶依赖性途径激活，但IL-4对PDE3的选择性激活不依赖MAP激酶（但可能依赖IRS-2/PI3-K）。
