Soppa Ulf, Schumacher Julian, Florencio Ortiz Victoria, Pasqualon Tobias, Tejedor Francisco J, Becker Walter
Institute of Pharmacology and Toxicology; Medical Faculty; RWTH Aachen University; Aachen, Germany; Instituto de Neurociencias; Consejo Superior de Investigaciones Cientificas (CSIC) and Universidad Miguel Hernandez; Alicante, Spain.
Institute of Pharmacology and Toxicology; Medical Faculty; RWTH Aachen University; Aachen, Germany.
Cell Cycle. 2014;13(13):2084-100. doi: 10.4161/cc.29104. Epub 2014 May 7.
A fundamental question in neurobiology is how the balance between proliferation and differentiation of neuronal precursors is maintained to ensure that the proper number of brain neurons is generated. Substantial evidence implicates DYRK1A (dual specificity tyrosine-phosphorylation-regulated kinase 1A) as a candidate gene responsible for altered neuronal development and brain abnormalities in Down syndrome. Recent findings support the hypothesis that DYRK1A is involved in cell cycle control. Nonetheless, how DYRK1A contributes to neuronal cell cycle regulation and thereby affects neurogenesis remains poorly understood. In the present study we have investigated the mechanisms by which DYRK1A affects cell cycle regulation and neuronal differentiation in a human cell model, mouse neurons, and mouse brain. Dependent on its kinase activity and correlated with the dosage of overexpression, DYRK1A blocked proliferation of SH-SY5Y neuroblastoma cells within 24 h and arrested the cells in G₁ phase. Sustained overexpression of DYRK1A induced G₀ cell cycle exit and neuronal differentiation. Furthermore, we provide evidence that DYRK1A modulated protein stability of cell cycle-regulatory proteins. DYRK1A reduced cellular Cyclin D1 levels by phosphorylation on Thr286, which is known to induce proteasomal degradation. In addition, DYRK1A phosphorylated p27(Kip1) on Ser10, resulting in protein stabilization. Inhibition of DYRK1A kinase activity reduced p27(Kip1) Ser10 phosphorylation in cultured hippocampal neurons and in embryonic mouse brain. In aggregate, these results suggest a novel mechanism by which overexpression of DYRK1A may promote premature neuronal differentiation and contribute to altered brain development in Down syndrome.
神经生物学中的一个基本问题是，如何维持神经元前体细胞增殖与分化之间的平衡，以确保生成适量的脑神经元。大量证据表明，DYRK1A（双特异性酪氨酸磷酸化调节激酶1A）是导致唐氏综合征中神经元发育改变和脑部异常的候选基因。最近的研究结果支持了DYRK1A参与细胞周期调控的假说。然而，DYRK1A如何促进神经元细胞周期调控，进而影响神经发生，目前仍知之甚少。在本研究中，我们探讨了DYRK1A在人类细胞模型、小鼠神经元和小鼠大脑中影响细胞周期调控和神经元分化的机制。依赖其激酶活性并与过表达剂量相关，DYRK1A在24小时内阻断了SH-SY5Y神经母细胞瘤细胞的增殖，并使细胞停滞在G₁期。持续过表达DYRK1A诱导细胞退出G₀细胞周期并促进神经元分化。此外，我们提供证据表明DYRK1A调节细胞周期调节蛋白的蛋白质稳定性。DYRK1A通过对Thr286位点的磷酸化降低细胞周期蛋白D1的水平，已知该位点的磷酸化可诱导蛋白酶体降解。此外，DYRK1A使p27（Kip1）的Ser10位点磷酸化，导致蛋白质稳定。抑制DYRK1A激酶活性可降低培养的海马神经元和胚胎小鼠大脑中p27（Kip1）Ser10位点的磷酸化。总的来说，这些结果表明了一种新机制，即DYRK1A的过表达可能促进神经元过早分化，并导致唐氏综合征中大脑发育改变。
