Rapid regulation of a cyclic AMP-specific phosphodiesterase (PDE IV) by forskolin and isoproterenol in LRM55 astroglial cells
Rapid regulation of a cyclic AMP-specific phosphodiesterase (PDE IV) by forskolin and isoproterenol in LRM55 astroglial cells
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DOI：
10.1016/0006-2952(96)00167-0
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发表时间：
1996-06-28
影响因子：
5.8
通讯作者：
LaVigne, E
中科院分区：
文献类型：
--
作者：
Madelian, V;LaVigne, E
升高细胞内环腺苷酸（cAMP）水平的完整的LRM 55星形胶质细胞与0.1 mM毛喉素或0.1 μ M异丙肾上腺素（IPR）孵育引起的可溶性cAMP磷酸二酯酶（PDE）活性的快速增加。激活不需要从头蛋白质合成，并且在处理15分钟后达到比基础PDE活性增加大于或等于100%的最大值。在DEAE层析后，在单个峰（峰3）中回收了活性增加;通过该方法分离的其他两个峰显示无变化。峰3具有PDE IV的所有特征：它对咯利普兰敏感，对CI-930和环GMP（cGMP）不敏感，对cAMP具有高亲和力（K-m接近或等于4 μ M），对cGMP具有非常低的亲和力（K-m > 100 μ M）。毛喉素处理导致峰3的V-max增加，而不影响其Km。在体外治疗的峰3与蛋白激酶A的催化亚基的活性增加，而治疗与碱性磷酸酶活性降低。响应于毛喉素和IPR的这种特异性PDE的快速活化代表了PDE IV通过似乎涉及其由cAMP依赖性蛋白激酶磷酸化的机制的新调节。
Elevation of intracellular cyclic AMP (cAMP) levels by incubation of intact LRM55 astroglial cells with 0.1 mM forskolin or 0.1 mu M isoproterenol (IPR) caused a rapid increase in soluble cAMP phosphodiesterase (PDE) activity. Activation did not require de novo protein synthesis and reached a maximum of greater than or equal to 100% increase over basal PDE activity after 15 min of treatment. The increase in activity was recovered in a single peak (peak 3) following DEAE chromatography; the other two peaks separated by this procedure showed no change. Peak 3 had all the characteristics of PDE IV: it was sensitive to rolipram, was insensitive to CI-930 and cyclic GMP (cGMP), had a high affinity for cAMP (K-m similar or equal to 4 mu M), and had a very low affinity for cGMP (K-m > 100 mu M). Forskolin treatment resulted in an increase of the V-max of peak 3 without affecting its K-m. In vitro treatment of peak 3 with the catalytic subunit of protein kinase A increased activity, whereas treatment with alkaline phosphatase decreased activity. The rapid activation of this specific PDE in response to forskolin and IPR represents a novel regulation of PDE IV by a mechanism that seems to involve its phosphorylation by a cAMP dependent protein kinase.