Single-cell RNA sequencing of cortical samples in Fam69c knockout mice. Single-cell RNA sequencing of cortical samples in Fam69c knockout mice

Synapse loss and memory decline are the primary features of neurodegenerative dementia. However, molecular underpinnings that drive memory loss remain largely unknown. Here, we report that FAM69C is a novel kinase critically involved in neurodegenerative dementia. Biochemical analyses uncovered that FAM69C is a serine/threonine kinase. We generated the Fam69c knockout mice, and showed by single-cell RNA sequencing that FAM69C deficiency drives cell-type-specific transcriptional changes relevant to synapse dysfunction. Electrophysiological, morphological and behavioral experiments demonstrated impairments in synaptic plasticity, dendritic spine density and memory in Fam69c knockout mice, as well as stress-induced neuronal death. Phosphoproteomic characterizations revealed FAM69C substrates involved in synaptic structure and function. Finally, reduced levels of FAM69C were found in postmortem brains of AD. Our study demonstrates that FAM69C is a protective regulator of memory and suggests FAM69C as a potential therapeutic target for memory loss in neurodegenerative dementia. Overall design: Study of cell-type-specific transcriptional changes in Fam69c wildtype and knockout cortical tissues using 10x Genomics platform.

突触丢失与记忆衰退是神经退行性痴呆的核心特征。然而，介导记忆丧失的分子基础在很大程度上仍未明确。在此，我们报道FAM69C是一种在神经退行性痴呆中发挥关键作用的新型激酶。生化分析结果显示，FAM69C属于丝氨酸/苏氨酸激酶。我们制备了Fam69c基因敲除小鼠，并通过单细胞RNA测序（single-cell RNA sequencing）证实，FAM69C缺失会诱发与突触功能障碍相关的细胞类型特异性转录组改变。电生理、形态学与行为学实验表明，Fam69c基因敲除小鼠出现突触可塑性、树突棘密度与记忆功能受损，同时存在应激诱导的神经元死亡。磷酸蛋白质组学分析揭示，FAM69C的底物参与突触结构与功能的调控。最后，我们在阿尔茨海默病（Alzheimer's disease, AD）患者的死后脑组织中检测到FAM69C的表达水平下调。本研究证实FAM69C是记忆的保护性调控因子，并提示其可作为神经退行性痴呆相关记忆丧失的潜在治疗靶点。实验整体设计：利用10x Genomics平台，对Fam69c野生型与基因敲除型小鼠的皮层组织开展细胞类型特异性转录组变化研究。