Ceramide activates heterotrimeric protein phosphatase 2A.
Ceramide activates heterotrimeric protein phosphatase 2A.
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DOI：
10.1016/s0021-9258(18)82288-8
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发表时间：
1993-07
期刊：
影响因子：
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通讯作者：
Rick T. DobrowskySS;Craig Kamibayashili;Marc C. Mumbyli;Yusuf A. HannunSIJ
中科院分区：
文献类型：
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作者：
Rick T. DobrowskySS;Craig Kamibayashili;Marc C. Mumbyli;Yusuf A. HannunSIJ
神经酰胺激活存在于大鼠T9胶质瘤细胞和大鼠脑中的胞质蛋白磷酸酶。神经酰胺活化的蛋白磷酸酶（CAPP）被发现与蛋白磷酸酶2A （PP2A）具有一些共同的特性，从而导致神经酰胺可能直接激活PP2A的假设。将PP2A分离为异源三聚体（AB'C, AB α C），异源二聚体（AC）或游离C亚基，并评估神经酰胺对催化活性的影响。5-20微米的c2 -神经酰胺对异三聚体PP2A的活性可达3.5倍，但对AC或c的活性没有影响。含有己醇基、癸醇基和肉豆蔻酰基链但不含硬脂酰酰基链的神经酰胺也能激活异三聚体PP2A。异三聚体PP2A的神经酰胺激活需要B亚基的存在，因为胰蛋白酶化或肝素治疗会消除神经酰胺的激活。异三聚体PP2A的激活对神经酰胺是特异性的，因为相关的鞘脂没有作用。此外，由于鞘碱中缺乏反式双键，二氢- c2 -神经酰胺在10微米时抑制AB'C活性达90%。发现c2 -神经酰胺立体异构体对AB'C和AB α C的激活特异性不同。dl - red - c2或3 - c2 -神经酰胺对AB'C的激活作用相似，而AB α C可被D-或l - red - c2 -神经酰胺激活，但不能被3 -异构体激活。从T9细胞分离的CAPP被d - red - c2 -神经酰胺最有效地激活。发现CAPP具有两个神经酰胺活化磷酸酶活性峰。活性的初始峰值与AB'C的洗脱一致，并被20微米的c2 -神经酰胺刺激1.8倍。在没有神经酰胺的情况下，磷酸酶活性的第二个峰值可以忽略不计，但被20微米的c2 -神经酰胺刺激了5.5倍。这些结果支持了神经酰胺是调节异三聚体PP2A活性的特定脂质第二信使的假设。
Ceramide activates a cytosolic protein phosphatase present in rat T9 glioma cells and rat brain. Ceramide-activated protein phosphatase (CAPP) was found to share several properties with protein phosphatase 2A (PP2A) leading to the hypothesis that ceramide may directly activate PP2A. PP2A was isolated as a heterotrimer (AB'C, AB alpha C), heterodimer (AC), or free C subunit, and the effect of ceramide on the catalytic activity was assessed. C2-ceramide, 5-20 microM, activated heterotrimeric PP2A up to 3.5-fold but had no effect on the activity of AC or C. Ceramides possessing hexanoyl, decanoyl, and myristoyl but not stearoyl acyl chains also activated heterotrimeric PP2A. Ceramide activation of heterotrimeric PP2A required the presence of a B subunit since trypsinization or heparin treatment abolished ceramide activation. Activation of heterotrimeric PP2A was specific for ceramide because related sphingolipids had no effect. Moreover, dihydro-C2-ceramide, which lacks the trans double bond in the sphingoid base, inhibited AB'C activity by > 90% at 10 microM. The specificity of activation of AB'C and AB alpha C by stereoisomers of C2-ceramide was found to differ. Whereas activation of AB'C by either DL-erythro- or threo-C2-ceramide was similar, AB alpha C was activated by either D- or L-erythro-C2-ceramide but not by the threo isomers. CAPP isolated from T9 cells was most effectively activated by D-erythro-C2-ceramide. CAPP was found to possess two peaks of ceramide activated phosphatase activity. The initial peak of activity was coincident with the elution of AB'C and was stimulated 1.8-fold by 20 microM C2-ceramide. A second peak of phosphatase activity was negligible in the absence of ceramide but was stimulated 5.5-fold by 20 microM C2-ceramide. These results support the hypothesis that ceramide is a specific lipid second messenger modulating heterotrimeric PP2A activity.