Characterization of growth factor-induced serine phosphorylation of tumor necrosis factor-α converting enzyme and of an alternatively translated polypeptide
Characterization of growth factor-induced serine phosphorylation of tumor necrosis factor-α converting enzyme and of an alternatively translated polypeptide
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DOI：
10.1074/jbc.m300331200
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发表时间：
2003-05-16
影响因子：
4.8
通讯作者：
Derynck, R
中科院分区：
文献类型：
--
作者：
Fan, HZ;Turck, CW;Derynck, R
肿瘤坏死因子- α转换酶（Tumor necrosis factor- α converting enzyme， TACE）是跨膜金属蛋白酶adamalysin家族的一个原型成员，它影响许多跨膜蛋白的外膜结构域切割和释放，包括转化生长因子- α。生长因子通过酪氨酸激酶受体以及其他刺激作用，通过激活Erk丝裂原活化蛋白（MAP）激酶途径诱导脱落，而不需要合成新的蛋白质。MAP激酶如何通过TACE调节脱落尚不清楚。我们现在报道TACE的细胞质结构域在生长因子刺激下被磷酸化。我们还发现了一个自然表达的较小的多肽，与TACE的大部分细胞质结构域相对应。我们将这种蛋白命名为SPRACT，它是通过TACE编码序列的替代翻译而衍生出来的，与TACE类似，它在生长因子和12-肉豆蔻酸13-乙酸磷的刺激下被磷酸化。磷氨基酸分析显示，生长因子诱导的TACE磷酸化只发生在丝氨酸上，而不发生在苏氨酸或酪氨酸上。色氨酸定位实验结合定点诱变发现，Ser（819）是生长因子诱导磷酸化的主要靶点，而Ser（791）则在生长因子刺激下经历去磷酸化。丝氨酸的磷酸化（819）而非去磷酸化（791）依赖于Erk MAP激酶途径的激活。SPRACT表达增加或TACE细胞质结构域突变使生长因子诱导的磷酸化失活，对TACE诱导的生长因子诱导的跨膜转化生长因子α脱落没有明显影响。SPRACT和TACE细胞质磷酸化的作用仍有待确定。
Tumor necrosis factor-alpha converting enzyme (TACE) is a prototype member of the adamalysin family of transmembrane metalloproteases that effects ectodomain cleavage and release of many transmembrane proteins, including transforming growth factor-alpha. Growth factors that act through tyrosine kinase receptors, as well as other stimuli, induce shedding through activation of the Erk mitogen-activated protein (MAP) kinase pathway without the need of new protein synthesis. How MAP kinase regulates shedding by TACE is not known. We now report that the cytoplasmic domain of TACE is phosphorylated in response to growth factor stimulation. We also identified a naturally expressed smaller polypeptide corresponding to most of the cytoplasmic domain of TACE. This protein, which we named SPRACT, is derived through alternative translation of the TACE-coding sequence and is, similarly to TACE, phosphorylated in response to growth factor and phorbol 12-myristate 13-acetate stimulation. Phosphoamino acid analysis revealed that growth factor-induced phosphorylation of TACE occurs only on serine and not on threonine or tyrosine. Tryptic mapping experiments coupled with site-directed mutagenesis identified Ser(819) as the major target of growth factor-induced phosphorylation, whereas Ser(791) undergoes dephosphorylation in response to growth factor stimulation. The phosphorylation of Ser(819), but not the dephosphorylation of Ser(791), depends on activation of the Erk MAP kinase pathway. Increased SPRACT expression or mutation of the TACE cytoplasmic domain to inactivate growth factor-induced phosphorylation did not detectably affect growth factor-induced shedding of transmembrane transforming growth factor-alpha by TACE. The roles of SPRACT and the cytoplasmic phosphorylation of TACE remain to be defined.