MEKK2 is required for T-cell receptor signals in JNK activation and interleukin-2 gene expression
MEKK2 is required for T-cell receptor signals in JNK activation and interleukin-2 gene expression
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DOI：
10.1074/jbc.m010134200
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发表时间：
2001-05-04
影响因子：
4.8
通讯作者：
Guo, ZJ
中科院分区：
文献类型：
--
作者：
Su, B;Cheng, JK;Guo, ZJ
c-Jun N-末端激酶（JNK）是丝裂原活化蛋白激酶（MAPK）基因家族的成员，并且对于细胞增殖、分化和凋亡是必需的。本研究从Jurkat T细胞中克隆了人MEK激酶（MEKK）2的全长cDNA，并证明它是T细胞中JNK级联反应的主要上游MAPK激酶。人MEKK 2 cDNA编码619个氨基酸，与已报道的鼠MEKK 2同源，与人和鼠MEKK 3在催化区的同源性为94%，在N端非催化区的同源性为60%。北方印迹分析显示MEKK 2在外周血白细胞中广泛表达，表达水平最高。在T细胞中，MEKK 2是JNK的强激活剂，但不激活细胞外信号调节激酶MAPK，并激活JNK依赖的AP-1报告基因的表达。MEKK 2还与抗CD 3抗体协同激活T细胞中的JNK，并且刺激T细胞导致诱导MEKK 2酪氨酸磷酸化。显著地，抗CDS和抗CD 28抗体诱导的JNK激活被显性负性MEKK 2突变体抑制，而12-O-十四烷酰基佛波醇-13-乙酸酯和Ca 2+离子载体A23187不抑制。AP-1和白细胞介素-2报告基因诱导T细胞也抑制显性阴性MEKK 2突变体。总之，我们的结果表明，人MEKK 2是T细胞受体/CD 3介导的JNK MAPK活化和白细胞介素2基因表达的关键信号分子。
The c-Jun N-terminal kinases (JNKs) are members of the mitogen-activated protein kinase (MAPK) gene family and are essential for cell proliferation, differentiation, and apoptosis. Previously we found that activation of JNK in T-cells required costimulation of both T-cell receptor and auxiliary receptors such as CD28, In this study, we cloned a full-length human MEK kinase (MEKK) 2 cDNA from Jurkat T-cells and demonstrated that it was a major upstream MAPK kinase kinase for the JNK cascade in T-cells. The human MEKK2 cDNA encoded a polypeptide of 619 amino acids and was the human counterpart of the reported murine MEKK2, It was 94% homologous with human and murine MEKK3 at the catalytic domains and 60% homologous at the N-terminal noncatalytic region. Northern blot analysis showed that MEKK2 was ubiquitously expressed, with the highest level in peripheral blood leukocytes, In T cells, MEKK2 was found to be a strong activator of JNK but not of extracellular signal-regulated kinase MAPKs and to activate JNK-dependent AP-1 reporter gene expression. MEKK2 also synergized with anti-CD3 antibody to activate JNK in T cells, and stimulation of T cells led to induction of MEKK2 tyrosine phosphorylation, Significantly, the JNK activation induced by anti-CDS and anti-CD28 antibodies, but not by 12-O-tetradecanoylphorbol-13-acetate and Ca2+ ionophore A23187, was inhibited by dominant negative MEKK2 mutants. AP-1 and interleukin-2 reporter gene induction in T-cells was also inhibited by dominant negative MEKK2 mutants. Taken together, our results showed that human MEKK2 is a key signaling molecule for T-cell receptor/CD3-mediated JNK MAPK activation and interleukin-2 gene expression.