The global genomic profile of hippocampal endothelial cells in fefemale diabetic mice is associated with cognitive dysfunction via alterations in cell adhesion and vascular permeability.

Type II diabetes mellitus (T2D) is a chronic metabolic disease, and a risk factor for cardiovascular disease and cerebrovascular dysfunction including vascular dementia. Sex differences in the prevalence of T2D, dementia, and global genomic changes in the brain have been observed; however, most studies have been performed in males exposing large knowledge gaps in females. Therefore, the aim of this study was to evaluate the consequence of T2D on cognitive function, and decipher underlying molecular transcriptomic mechanisms of endothelial cells in an important memory center, the hippocampus, in female diabetic mice. Adult female db/db and control wild type mice (n=10/group) were studied at age 18 weeks after which cognitive performance was assessed, metabolic parameters measured, and the hippocampus isolated for single nuclei RNA sequencing. db/db female mice exhibit characteristic T2D metabolism with hyperglycemia, hyperinsulinemia, and hyperlipidemia when compared to female WT mice. Female db/db mice presented cognitive decline compared to wild type mice. snRNAseq showed that T2D induced significant change in the global transcriptome profile of hippocampal endothelial cells by modulating expression of not only protein coding genes but also lncRNAs. These genes regulate cell-cell junctions, cell chemotaxis, actin cytoskeleton organization and cell adhesion, suggesting that diabetes increases endothelial cell permeability and therefore blood-brain permeability (BBB). Observed genomic changes also correlated with clinical Alzheimers and vascular dementia. In conclusion, T2D, by multiomic transcriptional and post transcriptional regulation, modulates the expression of genes in brain endothelial cells, resulting in endothelial cell dysfunction predictive of increased BBB permeability, and negatively impacts cognitive function. Wild type (C57BL/6J) and db/db female mice were fed a standard purified diet AIN-93M, for 8 wks. Mice were sacrificed at 18 weeks of age and hippocampus was dissected from left hemisphere and then stored at -80 degree celcius. Hippocampal nuclei was isolated and single nuclei RNA sequencing was performed. Brain hippocampal endothelial cells gene expression was analyzed using a multiomic approach for differential expression of protein and non-protein coding genes, gene networks, functional pathways, and transcription factors. Functional outcomes such as cognitive behavior and blood brain barrier permeability were also assessed.2型糖尿病（Type II diabetes mellitus, T2D）是一种慢性代谢性疾病，同时也是心血管疾病及包括血管性痴呆在内的脑血管功能障碍的危险因素。现有研究已观察到T2D、痴呆的患病率以及大脑整体基因组变化均存在性别差异，但目前绝大多数研究均以雄性动物为研究对象，导致雌性相关领域存在大量知识空白。因此本研究旨在评估T2D对雌性糖尿病小鼠认知功能的影响，并解析其重要记忆中枢——海马体内皮细胞的潜在分子转录组学机制。本研究选取成年雌性db/db糖尿病小鼠与野生型对照小鼠（每组n=10），在小鼠18周龄时开展实验：首先评估认知表现、检测代谢参数，随后分离海马体以进行单细胞核RNA测序（single nuclei RNA sequencing, snRNAseq）。与雌性野生型（wild type, WT）小鼠相比，雌性db/db小鼠呈现典型的T2D代谢表型，即高血糖、高胰岛素血症与高脂血症。相较于野生型小鼠，雌性db/db小鼠出现认知功能衰退。单细胞核RNA测序结果显示，T2D通过调控蛋白编码基因及长链非编码RNA（long non-coding RNAs, lncRNAs）的表达，显著改变了海马体内皮细胞的整体转录组谱。这些差异表达基因参与调控细胞间连接、细胞趋化、肌动蛋白细胞骨架组织及细胞黏附等过程，提示糖尿病会增强内皮细胞通透性，进而提升血脑屏障（blood-brain barrier, BBB）的通透性。观察到的基因组变化还与临床阿尔茨海默病及血管性痴呆存在相关性。综上，T2D通过多组学转录及转录后调控，调控脑内皮细胞的基因表达，导致内皮细胞功能异常，预示血脑屏障通透性升高，并对认知功能产生负面影响。本研究中，野生型（C57BL/6J品系）与db/db雌性小鼠均饲喂标准纯化饲料AIN-93M，饲养时长为8周。小鼠于18周龄时处死，从左侧大脑半球分离出海马体，随后置于-80℃冰箱保存。分离海马体细胞核并开展单细胞核RNA测序。采用多组学方法分析脑海马体内皮细胞的基因表达情况，包括蛋白编码与非蛋白编码基因的差异表达、基因网络、功能通路及转录因子。同时评估了认知行为、血脑屏障通透性等功能结局。