Single-cell RNA sequencing of Smek1-/- cortices and hippocampus. Single-cell RNA sequencing of Smek1-/- cortices and hippocampus

PPP4R3A, namely SMEK1 (Suppressor of Mek1 null), encodes a regulatory subunit of protein phosphatase 4 that is highly expressed in nervous system. Experimental autoimmune encephalomyelitis (EAE) is an animal disease model of multiple sclerosis (MS) that involves the immune system and central nervous system (CNS). However, it is unclear how genetic predispositions promote neuroinflammation in MS and EAE. Here, we investigated how partial loss-of-function of suppressor of SMEK1facilitates the onset of MS and EAE. Smek1 deficient mice showed more severe symptoms after EAE immunization. We performed single-cell RNA sequencing (scRNA-seq) on the cortices and hippocampus from 2-month old Smek1-/- and wild type littermates. Twelve cell types were identified in 6 tissue samples. Addtionally, we found a unique microglia subtype in Smek1-/- CNS that highly express IL-1β. Further analysis revealed enrichment of macrophage Csf1 in the novel microglia cluster. These findings confirmed that with loss of function of Smek1, a novel Csf1+ microglial cluster had a preactivated phenotype that may promote neuroinflammation. Overall design: Four samples of cortices and hippocampus from 2-month old wild type (WT) and Smek1-/- mice

PPP4R3A又名SMEK1（Suppressor of Mek1 null，即Mek1功能缺失抑制因子），编码蛋白磷酸酶4（protein phosphatase 4）的调节亚基，在神经系统中呈高表达。实验性自身免疫性脑脊髓炎（experimental autoimmune encephalomyelitis, EAE）是多发性硬化症（multiple sclerosis, MS）的动物模型，该疾病累及免疫系统与中枢神经系统（central nervous system, CNS）。目前尚不清楚遗传易感因素如何促进MS与EAE中的神经炎症。本研究探究了SMEK1部分功能缺失如何促进MS与EAE的发病。Smek1缺陷小鼠在接受EAE免疫后症状更为严重。我们对2月龄Smek1敲除（Smek1-/-）小鼠与野生型同窝仔鼠的皮层及海马组织进行了单细胞RNA测序（single-cell RNA sequencing, scRNA-seq），从6份组织样本中共鉴定出12种细胞类型。此外，我们在Smek1-/-小鼠的中枢神经系统中发现了一类独特的高表达白细胞介素1β（interleukin 1β, IL-1β）的小胶质细胞亚型。进一步分析显示，该新型小胶质细胞簇中富集了巨噬细胞集落刺激因子1（macrophage colony-stimulating factor 1, Csf1）。上述研究结果证实，当Smek1功能缺失时，一类新型的表达Csf1的小胶质细胞簇呈现预激活表型，可能促进神经炎症的发生。总体实验设计：选取2月龄野生型（wild type, WT）与Smek1-/-小鼠的皮层及海马组织，共4份样本。