Centrin 3 is an inhibitor of centrosomal Mps1 and antagonizes centrin 2 function.
Centrin 3 is an inhibitor of centrosomal Mps1 and antagonizes centrin 2 function.
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DOI：
10.1091/mbc.e14-07-1248
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发表时间：
2015-11-01
影响因子：
3.3
通讯作者：
Fisk HA
中科院分区：
文献类型：
--
作者：
Sawant DB;Majumder S;Perkins JL;Yang CH;Eyers PA;Fisk HA
Cetn3 通过阻断激活的自磷酸化来抑制体外和中心体的 Mps1 激酶活性，并且即使当 Mps1 以 10 倍摩尔过量存在时，也可以阻止 Mps1 磷酸化 Cetn2。 Cetn3 还阻止 Cetn2 掺入中心粒，但模仿 Cetn2 的磷酸化绕过了 Cetn3 的抑制作用。中心蛋白是一类小型钙结合蛋白，具有多种细胞功能，在中心体生物学中发挥着重要作用。我们之前将中心蛋白 2 和中心蛋白 3（Cetn2 和 Cetn3）确定为蛋白激酶 Mps1 的底物。然而，尽管Mps1磷酸化位点控制Cetn2在中心粒组装中的功能并促进中心粒过量产生，但Cetn2和Cetn3在功能上不可互换，我们在此表明Cetn3既是Mps1催化活性的生化抑制剂，又是中心体复制的生物抑制剂。在体外，Cetn3 抑制 Mps1 在 Thr-676（T 环自激活的已知位点）处的自磷酸化，并干扰 Cetn2 的 Mps1 依赖性磷酸化。 Cetn3 的细胞过度表达减弱了 Cetn2 掺入中心粒和中心体重复，而 Cetn3 的缺失会产生额外的中心粒。最后，Cetn3的过表达降低了中心体处Mps1 Thr-676的磷酸化，并且模仿Cetn2的Mps1依赖性磷酸化绕过了Cetn3的抑制作用，表明Cetn3的生物学效应是由于中心体处Mps1功能的抑制所致。
Cetn3 inhibits Mps1 kinase activity in vitro and at centrosomes by blocking activating autophosphorylation and can prevent Mps1 from phosphorylating Cetn2 even when Mps1 is present at 10-fold molar excess. Cetn3 also prevents incorporation of Cetn2 into centrioles, but mimicking phosphorylation of Cetn2 bypasses the inhibitory effects of Cetn3. Centrins are a family of small, calcium-binding proteins with diverse cellular functions that play an important role in centrosome biology. We previously identified centrin 2 and centrin 3 (Cetn2 and Cetn3) as substrates of the protein kinase Mps1. However, although Mps1 phosphorylation sites control the function of Cetn2 in centriole assembly and promote centriole overproduction, Cetn2 and Cetn3 are not functionally interchangeable, and we show here that Cetn3 is both a biochemical inhibitor of Mps1 catalytic activity and a biological inhibitor of centrosome duplication. In vitro, Cetn3 inhibits Mps1 autophosphorylation at Thr-676, a known site of T-loop autoactivation, and interferes with Mps1-dependent phosphorylation of Cetn2. The cellular overexpression of Cetn3 attenuates the incorporation of Cetn2 into centrioles and centrosome reduplication, whereas depletion of Cetn3 generates extra centrioles. Finally, overexpression of Cetn3 reduces Mps1 Thr-676 phosphorylation at centrosomes, and mimicking Mps1-dependent phosphorylation of Cetn2 bypasses the inhibitory effect of Cetn3, suggesting that the biological effects of Cetn3 are due to the inhibition of Mps1 function at centrosomes.