Actin-binding protein-280 binds the stress-activated protein kinase (SAPK) activator SEK-1 and is required for tumor necrosis factor-alpha activation of SAPK in melanoma cells
Actin-binding protein-280 binds the stress-activated protein kinase (SAPK) activator SEK-1 and is required for tumor necrosis factor-alpha activation of SAPK in melanoma cells
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DOI：
10.1074/jbc.272.5.2620
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发表时间：
1997-01-31
影响因子：
4.8
通讯作者：
Avruch, J
中科院分区：
文献类型：
--
作者：
Marti, A;Luo, ZJ;Avruch, J
SEK-1是一种双重特异性蛋白激酶，作为应激激活蛋白激酶（SAPKs）的直接上游激活剂之一，在体外和原位与肌动蛋白结合蛋白ABP-280特异性结合。SEK-1与ABP-280的羧基末端杆状节段结合，位于ABP羧基末端二聚化结构域的上游。在缺乏ABP-280表达的人黑色素瘤细胞中，以及在表达野生型ABP或肌动蛋白结合但二聚化缺陷的突变型ABP（ABP Delta CT 109）的这些细胞的稳定转化体中，评价了ABP-280对SAPK调节的影响。ABP-280缺陷型细胞对大多数刺激的反应显示出与ABP-280充满型细胞中观察到的相当的SAPK活化;然而，ABP-280缺陷型细胞未能显示出在ABP充满型细胞中观察到的SAPK的活跃的肿瘤坏死因子-α（TNE-α）活化，并且溶血磷脂酸使SAPK活化降低80%。二聚化缺陷突变体ABP-280的表达未能纠正缺陷性SAPK对溶血磷脂酸的反应，但基本上使SAPK的TNF-α活化正常化。因此，黑素瘤细胞中ABP-280的缺乏导致对TNF-α具有选择性的SAPK调节的缺陷，这可归因于ABP-280多肽本身的缺乏，而不是由此产生的肌动蛋白细胞骨架紊乱。ABP-280部分通过结合SEK-1参与TNF-α信号转导至SAPK。
SEK-1, a dual specificity protein kinase that serves as one of the immediate upstream activators of the stress-activated protein kinases (SAPKs), associates specifically with the actin-binding protein, ABP-280, in vitro and in situ. SEK-1 binds to the carboxyl-terminal rod segment of ABP-280, upstream of the ABP carboxyl-terminal dimerization domain. Activation of SEK-1 in situ increases the SEK-1 activity bound to ABP-280 without changing the amount of SEK-1 polypeptide bound.The influence of ABP-280 on SAPK regulation was evaluated in human melanoma cells that lack ABP-280 expression, and in stable transformants of these cells expressing wild type ABP, or an actin-binding but dimerization-deficient mutant ABP (ABP Delta CT109). ABP-280-deficient cells show an activation of SAPK in response to most stimuli that is comparable to that seen in ABP-280-replete cells; ABP-280-deficient cells, however, fail to show the brisk tumor necrosis factor-alpha (TNE-alpha) activation of SAPK seen in ABP-replete cells and have an 80% reduction in SAPK activation by lysophosphatidic acid. Expression of the dimerization-deficient mutant ABP-280 fails to correct the defective SAPK response to lysophosphatidic acid, but essentially normalizes the TNF-alpha activation of SAPK. Thus, a lack of ABP-280 in melanoma cells causes a defect in the regulation of SAPK that is selective for TNF-alpha and is attributable to the lack of ABP-280 polypeptide itself rather than to the disordered actin cytoskeleton that results therefrom. ABP-280 participates in TNF-alpha signal transduction to SAPKs, in part through the binding of SEK-1.