EXPRESSION/REGULATION OF PHOSPHODIESTERASE 3 ISOFORMS

环核苷酸磷酸二酯酶(PDE)通过催化cAMP和cGMP的水解，调节细胞内环核苷酸的浓度及其介导的生物反应，包括免疫/炎症反应。了解PDE亚型[属于十个基因家族(PDE1-10)]的细胞调控对于靶向治疗肺部疾病的特定PDE将具有越来越重要的意义。虽然单个细胞通常包含几个PDE基因家族的代表，但对单个细胞中参与不同PDE的细胞因子和生长因子调节的信号通路知之甚少。在小鼠FDCP2早幼粒细胞中，IL-4和IGF-1激活PDE3和PDE4，而IL-3仅激活PDE4。对肿瘤坏死因子α和JAK、PI3-K、PKC和MAPK激酶抑制剂的研究表明，IGF-1和IL-3都通过PI3-K依赖的信号激活PDE3和PDE4。在PI3-K下游，调节通路分化；依赖于MEK/MAPK的信号激活的是PDE4，而不是PDE3。因此，将野生型(Wt)、成分活性(CA)或非活性(Ki)形式的MEK和PKB永久地导入FDCP2细胞。对这些转基因细胞的研究表明，PDE4被依赖于MEK/MAPK的信号激活，而PDE3被磷酸化并被依赖于PKB的信号激活。重组小鼠(M)PDE3B在体外可以被PKB磷酸化和激活，而一个缺失共有的PKB磷酸化位点的MPDE3B突变体不被磷酸化/激活。在表达WT PKB的细胞中，促凋亡蛋白BAD被IGF-1磷酸化；8-BR-cAMP或PDE3抑制剂西洛雄胺阻断了磷酸化。这些和其他数据表明，PDE3B是PKB的下游靶点，如果不是底物的话，它可能作为PKB的效应器，调节cAMP池，至少部分地调节PKB对FDCP2细胞生存/增殖的影响。-PDE3、PDE4、环核苷酸水解、胰岛素、IGF-1、蛋白激酶B、FDCP2造血细胞、细胞存活/增殖

By catalyzing hydrolysis of cAMP and cGMP, cyclic nucleotide phosphodiesterases (PDEs) are critical regulators of intracellular concentrations of, and biological responses mediated by, cyclic nucleotides, including immune/inflammatory responses. Understanding cellular regulation of PDE isoforms [which belong to ten gene families (PDE1-10)] will be of increasing importance for targeting specific PDEs in treating pulmonary disorders. Although individual cells usually contain representatives of several PDE gene families, little is known of signalling pathways involved in cytokine and growth factor regulation of different PDEs in a single cell. In murine FDCP2 promyeloid cells, IL-4 and IGF-1 activate PDE3 and PDE4, whereas IL-3 activates only PDE4. Studies with TNFalpha and inhibitors of JAK, PI3- K, PKC, and MAPK kinases indicate that both IGF-1 and IL-3 activate PDE3 and PDE4 via PI3-K-dependent signals. Downstream of PI3-K, regulatory pathways diverge; PDE4, but not PDE3, is activated by MEK/MAPK-dependent signals. FDCP2 cells were, therefore, permanently transfected with wild type (wt), constitutively active (CA), or kinase inactive (KI) forms of MEK and PKB. Studies with these transfected cells indicated that PDE4 was activated by MEK/MAPK-dependent signals, and that PDE3 was phosphorylated and activated by PKB-dependent signals. Recombinant mouse (M) PDE3B was phosphorylated and activated in vitro by PKB; a truncated MPDE3B mutant lacking consensus PKB phosphorylation sites was not phosphorylated/activated. In cells expressing WT PKB, the proapoptotic protein BAD was phosphorylated in response to IGF-1; phosphorylation was blocked by 8-Br-cAMP or the PDE3 inhibitor cilostamide. These and other data suggest that PDE3B is a downstream target, if not substrate, of PKB and may function as an effector of PKB in regulation of cAMP pools that modulate, at least in part, effects of PKB on survival/proliferation of FDCP2 cells. - PDE3, PDE4, cyclic nucleotide hydrolysis, insulin, IGF-1, Protein Kinase B, FDCP2 hematopoietic cells, cell survival/proliferation