Cole Adam R, Causeret Frédéric, Yadirgi Gokhan, Hastie C James, McLauchlan Hilary, McManus Edward J, Hernández Félix, Eickholt Britta J, Nikolic Margareta, Sutherland Calum
Division of Pathology and Neurosciences, University of Dundee, Ninewells Hospital, Dundee DD1 9SY, Scotland.
J Biol Chem. 2006 Jun 16;281(24):16591-8. doi: 10.1074/jbc.M513344200. Epub 2006 Apr 12.
Collapsin response mediator proteins (CRMPs) are a family of neuron-enriched proteins that regulate neurite outgrowth and growth cone dynamics. Here, we show that Cdk5 phosphorylates CRMP1, CRMP2, and CRMP4, priming for subsequent phosphorylation by GSK3 in vitro. In contrast, DYRK2 phosphorylates and primes CRMP4 only. The Cdk5 and DYRK2 inhibitor purvalanol decreases the phosphorylation of CRMP proteins in neurons, whereas CRMP1 and CRMP2, but not CRMP4, phosphorylation is decreased in Cdk5(-/-) cortices. Stimulation of neuroblastoma cells with IGF1 or TPA decreases GSK3 activity concomitantly with CRMP2 and CRMP4 phosphorylation. Conversely, increased GSK3 activity is not sufficient to increase CRMP phosphorylation. However, the growth cone collapse-inducing protein Sema3A increases Cdk5 activity and promotes phosphorylation of CRMP2 (but not CRMP4). Therefore, inhibition of GSK3 alters phosphorylation of all CRMP isoforms; however, individual isoforms can be differentially regulated by their respective priming kinase. This is the first GSK3 substrate found to be regulated in this manner and may explain the hyperphosphorylation of CRMP2 observed in Alzheimer's disease.
塌陷反应中介蛋白（CRMPs）是一类在神经元中高度富集的蛋白质家族，可调节神经突生长和生长锥动力学。在此，我们表明，细胞周期蛋白依赖性激酶5（Cdk5）可使CRMP1、CRMP2和CRMP4磷酸化，从而为随后糖原合成酶激酶3（GSK3）在体外的磷酸化作用做好准备。相比之下，双重特异性酪氨酸磷酸化调节激酶2（DYRK2）仅使CRMP4磷酸化并做好准备。Cdk5和DYRK2抑制剂嘌呤醇可降低神经元中CRMP蛋白的磷酸化水平，而在Cdk5基因敲除小鼠的皮质中，CRMP1和CRMP2（而非CRMP4）的磷酸化水平降低。用胰岛素样生长因子1（IGF1）或佛波酯（TPA）刺激神经母细胞瘤细胞，会伴随CRMP2和CRMP4磷酸化水平的降低而降低GSK3活性。相反，GSK3活性增加并不足以增加CRMP的磷酸化水平。然而，诱导生长锥塌陷的蛋白Sema3A可增加Cdk5活性并促进CRMP2（而非CRMP4）的磷酸化。因此，抑制GSK3会改变所有CRMP亚型的磷酸化水平；然而，各个亚型可由其各自的起始激酶进行差异调节。这是首个被发现以这种方式调节的GSK3底物，可能解释了在阿尔茨海默病中观察到的CRMP2的过度磷酸化现象。
