Phosphorylation controls CLIMP-63-mediated anchoring of the endoplasmic reticulum to microtubules
Phosphorylation controls CLIMP-63-mediated anchoring of the endoplasmic reticulum to microtubules
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DOI：
10.1091/mbc.e04-07-0554
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发表时间：
2005-04-01
影响因子：
3.3
通讯作者：
Hauri, HP
中科院分区：
文献类型：
--
作者：
Vedrenne, C;Klopfenstein, DR;Hauri, HP
微管结合的63-kDa的细胞质连接膜蛋白（CLIMP-63）是连接内质网（ER）和微管的膜蛋白。在这里，我们测试了这种相互作用是否受磷酸化调节。用P-32进行的代谢标记显示，CLIMP-63是在有丝分裂期间磷酸化增加的磷蛋白。有丝分裂细胞的CLIMP-63在体外不能与微管结合。有丝分裂磷酸化可以通过CLIMP-63胞质结构域中丝氨酸3、17和19的突变来阻止。当这些残基突变为谷氨酸，从而模拟有丝分裂磷酸化时，CLIMP-63在体外不再与微管结合。在间期细胞中CLIMP-63的磷酸化模拟有丝分裂形式的过表达导致细胞核周围的ER塌陷，使微管网络保持完整。结果表明，需要CLIMP-63介导的ER稳定锚定到微管，以维持ER在间期的空间分布，并且这种相互作用在有丝分裂期间通过CLIMP-63的磷酸化而被消除。
The microtubule-binding 63-kDa cytoskeleton-linking membrane protein (CLIMP-63) is an integral membrane protein that links the endoplasmic reticulum (ER) to microtubules. Here, we tested whether this interaction is regulated by phosphorylation. Metabolic labeling with P-32 showed that CLIMP-63 is a phosphoprotein with increased phosphorylation during mitosis. CLIMP-63 of mitotic cells is unable to bind to microtubules in vitro. Mitotic phosphorylation can be prevented by mutation of serines 3, 17, and 19 in the cytoplasmic domain of CLIMP-63. When these residues are mutated to glutamic acid, and hence mimic mitotic phosphorylation, CLIMP-63 does no longer bind to microtubules in vitro. Overexpression of the phospho-mimicking mitotic form of CLIMP-63 in interphase cells leads to a collapse of the ER around the nucleus, leaving the microtubular network intact. The results suggest that CLIMP-63-mediated stable anchoring of the ER to microtubules is required to maintain the spatial distribution of the ER during interphase and that this interaction is abolished by phosphorylation of CLIMP-63 during mitosis.