Zou Jianyu, Lei Changbin, Zhang Yunlong, Ma Ao, Meng Zhichao, Zhu Jiehao, Lin Hongsheng, Zhang Guowei, Liang Yaozhong, Tan Minghui
Department of Orthopedics, The First Affiliated Hospital of Jinan University, Guangzhou 510630, China.
Department of Orthopedics, Affiliated Hospital of Xiangnan University (Clinical College), Chenzhou, Hunan 423000, China.
J Neurosci. 2025 Jul 11. doi: 10.1523/JNEUROSCI.1995-24.2025.
Neurite outgrowth is critically controlled by calcium influx-mediated cytoskeleton dynamics. Spastin, a AAA ATPase microtubule severing protein, also plays an important role in neurite outgrowth. However, the detailed mechanisms underlying post-transcriptional fine-tuning spastin activity, particularly in the context of calcium signaling, remain elusive. Here, we identified Ca/calmodulin-dependent protein kinase II beta isoform (CaMKIIβ) acted as an upstream kinase to mediate the phosphorylation of spastin. CaMKIIβ interacted with and phosphorylated spastin on Ser233 and Ser562 amino acids. Moreover, CaMKIIβ-mediated phosphorylation reduced the poly-ubiquitination level of spastin and suppressed its proteasomal degradation. This enhanced protein stability by CaMKIIβ increased the microtubule severing activity of spastin and coordinately promoted the neurite outgrowth in hippocampal neurons. Inhibition of spastin or CaMKIIβ impaired synaptic activity, as evidenced by reduced frequency and amplitude of miniature excitatory postsynaptic currents (mEPSCs). Behaviorally, treatment with spastin or CaMKIIβ inhibitors led to deficits in short-term working memory and spatial learning, as assessed by Y-maze and Morris water maze tests in male mice, respectively. In general, this study unveils a novel mechanism whereby CaMKIIβ-mediated phosphorylation of spastin connects extracellular calcium signaling to the regulation of cytoskeleton dynamics and neurite outgrowth. This work uncovers a novel molecular mechanism that links calcium signaling to cytoskeletal remodeling and neural function. We demonstrate that CaMKIIβ phosphorylates spastin, enhancing its stability by reducing polyubiquitination and proteasomal degradation. This post-transcriptional regulation increases spastin's microtubule-severing activity, thereby promoting neurite outgrowth in hippocampal neurons. Furthermore, inhibition of CaMKIIβ or spastin impairs synaptic transmission and cognitive performance, highlighting their critical roles in neuronal development and function. Overall, the study identifies CaMKIIβ as a key upstream regulator of spastin, offering new insights into how calcium influx governs neurite extension and memory-related behavior, with potential implications for neurological disease mechanisms and therapeutic strategies.
神经突生长受到钙内流介导的细胞骨架动力学的严格控制。痉挛蛋白是一种AAA型ATP酶微管切断蛋白，在神经突生长中也起着重要作用。然而，转录后微调痉挛蛋白活性的详细机制，特别是在钙信号传导的背景下，仍然不清楚。在这里，我们发现钙/钙调蛋白依赖性蛋白激酶IIβ亚型（CaMKIIβ）作为上游激酶介导痉挛蛋白的磷酸化。CaMKIIβ与痉挛蛋白相互作用并在丝氨酸233和丝氨酸562氨基酸位点使其磷酸化。此外，CaMKIIβ介导的磷酸化降低了痉挛蛋白的多聚泛素化水平并抑制其蛋白酶体降解。CaMKIIβ增强的这种蛋白质稳定性增加了痉挛蛋白的微管切断活性，并协同促进海马神经元的神经突生长。痉挛蛋白或CaMKIIβ的抑制损害了突触活动, 微小兴奋性突触后电流（mEPSCs）的频率和幅度降低证明了这一点。在行为上，分别通过雄性小鼠的Y迷宫和莫里斯水迷宫测试评估，用痉挛蛋白或CaMKIIβ抑制剂治疗导致短期工作记忆和空间学习缺陷。总的来说，这项研究揭示了一种新机制，即CaMKIIβ介导的痉挛蛋白磷酸化将细胞外钙信号传导与细胞骨架动力学和神经突生长的调节联系起来。这项工作揭示了一种将钙信号传导与细胞骨架重塑和神经功能联系起来的新分子机制。我们证明CaMKIIβ使痉挛蛋白磷酸化，通过减少多聚泛素化和蛋白酶体降解来增强其稳定性。这种转录后调节增加了痉挛蛋白的微管切断活性，从而促进海马神经元的神经突生长。此外，CaMKIIβ或痉挛蛋白的抑制损害突触传递和认知表现，突出了它们在神经元发育和功能中的关键作用。总体而言，该研究确定CaMKIIβ是痉挛蛋白的关键上游调节因子，为钙内流如何控制神经突延伸和记忆相关行为提供了新见解，对神经疾病机制和治疗策略具有潜在意义。
