Huang Tzyy-Nan, Hsueh Yi-Ping
From the Graduate Institute of Life Sciences, National Defense Medical Center and the Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.
J Psychiatry Neurosci. 2017 Jan;42(1):37-47. doi: 10.1503/jpn.150359.
Human genetic studies have indicated that mutations in calcium/calmodulin-dependent serine protein kinase () result in X-linked mental retardation and autism-spectrum disorders. We aimed to establish a mouse model to study how regulates mental ability.
Because encodes a multidomain scaffold protein, a possible strategy to dissect how CASK regulates mental ability and cognition is to disrupt specific protein-protein interactions of CASK in vivo and then investigate the impact of individual specific protein interactions. Previous in vitro analyses indicated that a rat CASK T724A mutation reduces the interaction between CASK and T-brain-1 (TBR1) in transfected COS cells. Because TBR1 is critical for glutamate receptor, ionotropic, -methyl-D-aspartate receptor subunit 2B () expression and is a causative gene for autism and intellectual disability, we then generated CASK T740A (corresponding to rat CASK T724A) mutant mice using a gene-targeting approach. Immunoblotting, coimmunoprecipitation, histological methods and behavioural assays (including home cage, open field, auditory and contextual fear conditioning and conditioned taste aversion) were applied to investigate expression of CASK and its related proteins, the protein-protein interactions of CASK, and anatomic and behavioural features of CASK T740A mice.
The CASK T740A mutation attenuated the interaction between CASK and TBR1 in the brain. However, CASK T740A mice were generally healthy, without obvious defects in brain morphology. The most dramatic defect among the mutant mice was in extinction of associative memory, though acquisition was normal.
The functions of other CASK protein interactions cannot be addressed using CASK T740A mice.
Disruption of the CASK and TBR1 interaction impairs extinction, suggesting the involvement of CASK in cognitive flexibility.
人类遗传学研究表明，钙/钙调蛋白依赖性丝氨酸蛋白激酶（CASK）的突变会导致X连锁智力障碍和自闭症谱系障碍。我们旨在建立一个小鼠模型，以研究CASK如何调节智力。
由于CASK编码一种多结构域支架蛋白，剖析CASK如何调节智力和认知的一种可能策略是在体内破坏CASK特定的蛋白质-蛋白质相互作用，然后研究单个特定蛋白质相互作用的影响。先前的体外分析表明，大鼠CASK T724A突变会降低转染的COS细胞中CASK与T脑-1（TBR1）之间的相互作用。由于TBR1对谷氨酸受体、离子型、N-甲基-D-天冬氨酸受体亚基2B（GRIN2B）的表达至关重要，并且是自闭症和智力残疾的致病基因，因此我们采用基因靶向方法生成了CASK T740A（对应于大鼠CASK T724A）突变小鼠。应用免疫印迹、免疫共沉淀、组织学方法和行为分析（包括饲养笼、旷场、听觉和情境恐惧条件反射以及条件性味觉厌恶）来研究CASK及其相关蛋白的表达、CASK的蛋白质-蛋白质相互作用以及CASK T740A小鼠的解剖和行为特征。
CASK T740A突变减弱了大脑中CASK与TBR1之间的相互作用。然而，CASK T740A小鼠总体健康，脑形态无明显缺陷。突变小鼠中最显著的缺陷是联想记忆的消退，尽管获取过程正常。
使用CASK T740A小鼠无法研究其他CASK蛋白质相互作用的功能。
CASK与TBR1相互作用的破坏会损害消退，提示CASK参与认知灵活性。
