JNK and Ceramide Kinase Govern the Biogenesis of Lipid Droplets through Activation of Group IVA Phospholipase A2
JNK and Ceramide Kinase Govern the Biogenesis of Lipid Droplets through Activation of Group IVA Phospholipase A2
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DOI：
10.1074/jbc.m109.061515
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发表时间：
2009-11-20
影响因子：
4.8
通讯作者：
Claro, Enrique
中科院分区：
文献类型：
--
作者：
Gubern, Albert;Barcelo-Torns, Miquel;Claro, Enrique
由血清诱导的脂滴（LD）的生物发生依赖于IVA族磷脂酶A（2）（cPLA（2）α）。这项工作剖析了导致cPLA（2）α激活和LD生物发生的途径。这两个过程都是Ca 2+非依赖性的，因为它们发生在药理学阻断血清或与1，2-双（2-氨基苯氧基）乙烷-N，N，N '，N'-四乙酸四（乙酰氧基甲酯）螯合引起的Ca 2+瞬变后。cPLA（2）α中的单突变D43 N，消除了其Ca 2+结合能力和向膜的转运，但不影响酶的活化和LD的形成。与此相反，突变S505 A并不影响膜搬迁的酶在响应Ca 2+，但阻止其磷酸化，激活，和LD的外观。不同丝裂原活化蛋白激酶的特异性激活剂的表达表明cPLA（2）alpha在Ser-505的磷酸化是由于JNK。这通过上游激活剂MEKK 1的显性阴性形式的药理学抑制和表达得到证实。LD的生物合成伴随着神经酰胺1-磷酸的合成增加。其合成酶神经酰胺激酶的过表达增加cPLA（2）α 505位丝氨酸的磷酸化和LD的形成，其下调则阻断cPLA（2）α的磷酸化和LD的生物合成。这些结果表明，血清诱导的LD生物合成受JNK和神经酰胺激酶的调节。
The biogenesis of lipid droplets (LD) induced by serum depends on group IVA phospholipase A(2) (cPLA(2)alpha). This work dissects the pathway leading to cPLA(2)alpha activation and LD biogenesis. Both processes were Ca2+-independent, as they took place after pharmacological blockade of Ca2+ transients elicited by serum or chelation with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester). The single mutation D43N in cPLA(2)alpha, which abrogates its Ca2+ binding capacity and translocation to membranes, did not affect enzyme activation and formation of LD. In contrast, the mutation S505A did not affect membrane relocation of the enzyme in response to Ca2+ but prevented its phosphorylation, activation, and the appearance of LD. Expression of specific activators of different mitogen-activated protein kinases showed that phosphorylation of cPLA(2)alpha at Ser-505 is due to JNK. This was confirmed by pharmacological inhibition and expression of a dominant-negative form of the upstream activator MEKK1. LD biogenesis was accompanied by increased synthesis of ceramide 1-phosphate. Overexpression of its synthesizing enzyme ceramide kinase increased phosphorylation of cPLA(2)alpha at Ser-505 and formation of LD, and its down-regulation blocked the phosphorylation of cPLA(2)alpha and LD biogenesis. These results demonstrate that LD biogenesis induced by serum is regulated by JNK and ceramide kinase.