Cold-inducible RNA-binding protein (Cirp) interacts with Dyrk1b/Mirk and promotes proliferation of immature male germ cells in mice
Cold-inducible RNA-binding protein (Cirp) interacts with Dyrk1b/Mirk and promotes proliferation of immature male germ cells in mice
复制标题
DOI：
10.1073/pnas.1121524109
复制
发表时间：
2012-07-03
影响因子：
11.1
通讯作者：
Fujita, Jun
中科院分区：
文献类型：
--
作者：
Masuda, Tomoko;Itoh, Katsuhiko;Fujita, Jun
冷诱导RNA结合蛋白（Cirp）是第一个在哺乳动物中发现的冷休克蛋白。它在结构上与细菌冷休克蛋白完全不同，并且在对轻度但不严重的低温的反应中被诱导。为了阐明Cirp在体内的生理功能，我们产生了Cirp敲除小鼠。他们没有表现出明显的异常，也没有生育能力的缺陷，但未分化的精原细胞的数量显着减少，精子发生的恢复延迟后，与细胞毒性剂，白消安治疗。Cirp可加速小鼠胚胎成纤维细胞从G0期到G1期和从G1期到S期的细胞周期进程。Cirp直接与双特异性酪氨酸磷酸化调节激酶1B（Dyrk1b，也称为Mirk）结合，并抑制其与p27的结合，导致p27的磷酸化减少和不稳定。Cirp不影响Dyrk1b与细胞周期蛋白D1的结合，但抑制Dyrk1b对细胞周期蛋白D1的磷酸化，导致细胞周期蛋白D1的稳定。在精原细胞系GC-1spg中，Cirp表达的抑制增加了p27的蛋白水平，降低了细胞周期蛋白D1的蛋白水平，并降低了依赖于Dyrk1b的生长速率。在cirp基因敲除小鼠的未分化精原细胞中，观察到p27和cyclin D1蛋白水平以及G0期细胞百分比的一致变化。在未分化的野生型小鼠精原细胞，Cirp和Dyrk1b共定位于细胞核。因此，我们的研究表明，Cirp功能微调未分化精原细胞的增殖与Dyrk1b相互作用。
Cold-inducible RNA-binding protein (Cirp) was the first cold-shock protein identified in mammals. It is structurally quite different from bacterial cold-shock proteins and is induced in response to mild, but not severe, hypothermia. To clarify the physiological function of Cirp in vivo, we produced cirp-knockout mice. They showed neither gross abnormality nor defect in fertility, but the number of undifferentiated spermatogonia was significantly reduced and the recovery of spermatogenesis was delayed after treatment with a cytotoxic agent, busulfan. Cirp accelerated cell-cycle progression from G0 to G1 as well as from G1 to S phase in cultured mouse embryonic fibroblasts. Cirp directly bound to dual-specificity tyrosine-phosphorylation-regulated kinase 1B (Dyrk1b, also called Mirk) and inhibited its binding to p27, resulting in decreased phosphorylation and destabilization of p27. Cirp did not affect binding of Dyrk1b to cyclin D1 but inhibited phosphorylation of cyclin D1 by Dyrk1b, resulting in cyclin D1 stabilization. In the spermatogonial cell line GC-1spg, suppression of Cirp expression increased the protein level of p27, decreased that of cyclin D1, and decreased the growth rate, which depended on Dyrk1b. Consistent changes in the protein levels of p27 and cyclin D1 as well as the percentage of cells in G0 phase were observed in undifferentiated spermatogonia of cirp-knockout mice. In undifferentiated spermatogonia of wild-type mice, Cirp and Dyrk1b colocalized in the nucleus. Thus, our study demonstrates that Cirp functions to fine-tune the proliferation of undifferentiated spermatogonia by interacting with Dyrk1b.