Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, P. R. China.
Department of Neurology, the First Affiliated Hospital of Hainan Medical University, Haikou, China.
J Alzheimers Dis. 2019;70(2):573-585. doi: 10.3233/JAD-190099.
Under stress stimulation, p25 is generated by cleavage of p35 and acts as an activator of cyclin-dependent kinase 5 (Cdk5) like p35. Unlike Cdk5/p35, which is important for brain development, aberrant activity of Cdk5/p25 plays a pathological role in neurodegenerative diseases, such as Alzheimer's disease, by inducing hyperphosphorylation of downstream substrates related to pathological progression. A truncated fragment of the c-terminus of p35, the Cdk5 inhibitory peptide (CIP), selectively inhibits Cdk5/ p25 activity in cultured neurons and in CIP/p25 tetra-transgenic mice.
First, we aimed to establish a p25 overexpression adult mouse model, then to evaluate whether CIP delivered by adeno-associated virus serotype 9 (AAV9) can ameliorate neuronal toxicity induced by p25.
The p25 overexpression mouse model was established by intracerebroventricular (i.c.v.) injection of AAV8-GFP-p25 in 8-week-old mice. One month later, these mice were i.c.v. injected with AAV9-CIP-T2A-mCherry or AAV9 vector as control. Pathological and behavioral changes were assessed 3-months post-injection in all mice.
The p25 overexpression mice displayed hyperphosphorylation of tau at multiple sites, activation of astrocytes, and elevated inflammatory factors, including IL-1 and TNF-α, which were significantly decreased by the administration of CIP. However, Aβ deposition and microgliosis were not obvious in p25 overexpression mice. In addition, a significant learning decline and anxiety-like behavior were induced by p25 toxicity, and CIP treatment improved learning ability in p25 mice.
AAV-mediated p25 overexpression mouse model is easy to construct to study p25-induced neuronal toxicity. Application of CIP after p25 insult reverses the pathological changes and behavioral abnormalities.
在应激刺激下,p25 通过切割 p35 产生,其作用类似于 p35 的有丝分裂原激活蛋白激酶 5(Cdk5)激活剂。与对大脑发育很重要的 Cdk5/p35 不同,Cdk5/p25 的异常活性在神经退行性疾病中发挥病理性作用,如阿尔茨海默病,通过诱导与病理进展相关的下游底物的过度磷酸化。p35 C 端的截断片段,即 Cdk5 抑制肽(CIP),在培养神经元和 CIP/p25 四转基因小鼠中选择性抑制 Cdk5/p25 活性。
首先,我们旨在建立 p25 过表达成年小鼠模型,然后评估腺相关病毒血清型 9(AAV9)递送的 CIP 是否可以改善 p25 诱导的神经元毒性。
通过侧脑室(i.c.v.)注射 AAV8-GFP-p25 在 8 周龄小鼠中建立 p25 过表达小鼠模型。一个月后,这些小鼠通过 i.c.v. 注射 AAV9-CIP-T2A-mCherry 或 AAV9 载体作为对照。所有小鼠在注射后 3 个月评估病理和行为变化。
p25 过表达小鼠表现出 tau 多个位点的过度磷酸化、星形胶质细胞激活和炎症因子升高,包括 IL-1 和 TNF-α,这些因子在 CIP 给药后显著降低。然而,p25 过表达小鼠中没有明显的 Aβ 沉积和小胶质细胞增生。此外,p25 毒性诱导了明显的学习能力下降和焦虑样行为,CIP 治疗改善了 p25 小鼠的学习能力。
AAV 介导的 p25 过表达小鼠模型易于构建,用于研究 p25 诱导的神经元毒性。p25 损伤后应用 CIP 可逆转病理变化和行为异常。