The receptor tyrosine kinase Ror2 associates with and is activated by casein kinase Iε
The receptor tyrosine kinase Ror2 associates with and is activated by casein kinase Iε
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DOI：
10.1074/jbc.m409039200
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发表时间：
2004-11-26
影响因子：
4.8
通讯作者：
Minami, Y
中科院分区：
文献类型：
--
作者：
Kani, S;Oishi, I;Minami, Y
Ror 2是哺乳动物受体酪氨酸激酶Ror家族的一员，在发育形态发生中起着重要作用，尽管Ror 2激活的潜在机制在很大程度上仍然难以捉摸。我们发现，当在哺乳动物细胞中表达时，Ror 2与酪蛋白激酶I β（CKI β）相关，CKI β是Wnt信号传导的关键调节因子。这种关联主要通过Ror 2的胞质C-末端富含脯氨酸的结构域发生。我们还表明，Ror 2是磷酸化的CKIstatin的丝氨酸/苏氨酸残基，在其C-末端丝氨酸/苏氨酸丰富的2域，导致Ror 2的酪氨酸残基的自磷酸化。此外，发现Ror 2与CKI β的缔合是CKI β对其丝氨酸/苏氨酸磷酸化所必需的。Ror 2中酪氨酸残基的定点突变揭示了磷酸化位点包含在富含脯氨酸的结构域中的5个酪氨酸残基中，但不包含在酪氨酸激酶结构域中的4个酪氨酸残基中。此外，我们表明，在哺乳动物细胞中，CKIepsilon介导的丝氨酸/苏氨酸和酪氨酸残基的磷酸化的Ror 2的G蛋白偶联受体激酶2，一个激酶的酪氨酸磷酸化的发展表达模式，是非常相似的Ror 2。有趣的是，缺少5个酪氨酸残基（包括自磷酸化位点）的Ror 2突变体不能使G蛋白偶联受体激酶2酪氨酸磷酸化。这表明Ror 2的自磷酸化是其酪氨酸激酶活性完全激活所必需的。这些发现证明了CKI 3在调节Ror 2酪氨酸激酶中的新作用。
Ror2, a member of the mammalian Ror family of receptor tyrosine kinases, plays important roles in developmental morphogenesis, although the mechanism underlying activation of Ror2 remains largely elusive. We show that when expressed in mammalian cells, Ror2 associates with casein kinase Iepsilon (CKIepsilon), a crucial regulator of Wnt signaling. This association occurs primarily via the cytoplasmic C-terminal proline-rich domain of Ror2. We also show that Ror2 is phosphorylated by CKIepsilon on serine/threonine residues, in its C-terminal serine/ threonine-rich 2 domain, resulting in autophosphorylation of Ror2 on tyrosine residues. Furthermore, it was found that association of Ror2 with CKIepsilon is required for its serine/ threonine phosphorylation by CKIepsilon. Site-directed mutagenesis of tyrosine residues in Ror2 reveals that the sites of phosphorylation are contained among the five tyrosine residues in the proline-rich domain but not among the four tyrosine residues in the tyrosine kinase domain. Moreover, we show that in mammalian cells, CKIepsilon-mediated phosphorylation of Ror2 on serine/ threonine and tyrosine residues is followed by the tyrosine phosphorylation of G protein-coupled receptor kinase 2, a kinase with a developmental expression pattern that is remarkably similar to that of Ror2. Intriguingly, a mutant of Ror2 lacking five tyrosine residues, including the autophosphorylation sites, fails to tyrosine phosphorylate G protein-coupled receptor kinase 2. This indicates that autophosphorylation of Ror2 is required for full activation of its tyrosine kinase activity. These findings demonstrate a novel role for CKIepsilon in the regulation of Ror2 tyrosine kinase.