The contribution of X-chromosome-linked genes to cellular phenotypes and AD-related pathology in Down Syndrome

X 染色体连锁基因对唐氏综合症细胞表型和 AD 相关病理的贡献

• 批准号: 10574254
• 负责人: ELLA ZELDICH
• 金额: $ 24.75万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-12-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10574254
• 关键词: Adult; Affect; Alzheimer' s Disease; Alzheimer' s disease pathology; Alzheimer' s disease patient; Astrocytes; Autopsy; Binding; Binding Sites; Biology; Brain; Brain Pathology; Cell Line; Cell model; Cells; Chromosome 21; Cognitive; Cognitive deficits; Data; Data Set; Deposition; Development; Down Syndrome; Down-Regulation; Early Onset Alzheimer Disease; Evaluation; Exhibits; Family member; Gene Expression; Gene Family; Genes; Genetic; Genetic Transcription; Global Change; Histologic; Human; Human Chromosomes; Individual; Intellectual functioning disability; Link; Mental disorders; Modeling; Myelin; NGFRAP1 gene; Neocortex; Nerve Degeneration; Neurons; Oligodendroglia; Pathologic; Pathology; Patients; Pattern; Phenotype; Play; Prefrontal Cortex; Process; Psyche structure; Reporting; Resolution; Schizophrenia; Synapses; System; Testing; Therapeutic; Therapeutic Intervention; Time; Tissues; Transcript; Trisomy; Untranslated RNA; Up-Regulation; X Chromosome; X Inactivation; abeta deposition; autism spectrum disorder; brain abnormalities; brain cell; brain tissue; differential expression; disability; gene product; gene repression; genome-wide; hyperphosphorylated tau; induced pluripotent stem cell; molecular phenotype; motor disorder; myelination; neglect; neocortical; overexpression; prenatal; preservation; restoration; single-cell RNA sequencing; small hairpin RNA; success; transcription factor; transcription factor S-II; transcriptome; transcriptomic profiling; transcriptomics

Abstract Down Syndrome (DS) is caused by triplication of human chromosome 21 (HSA21), resulting in intellectual disability, motor dysfunction, and early onset Alzheimer’s Disease (AD). The mechanistic connection between triplicated genes in DS and the all-encompassing imbalance in gene expression underlying the abnormalities seen in DS brain cells has not been established. It is also unknown how this global transcriptomic disbalance leads to intellectual disability and early development of AD-related pathology in DS, nor what genes play a key role in these processes. In our preliminary studies, we generated oligocortical spheroids (OLS) derived from DS isogenic induced pluripotent stem cell (iPSCs) lines. Trisomic OLS recapitulate DS and AD- related cellular phenotypes, including reduced cortical volume, aberrant myelination and pathological depositions of amyloid beta and hyper-phosphorylated tau. Through our single-cell RNA sequencing (scRNA-seq) analysis of euploid and trisomic OLS, we identified a cluster of X- linked genes containing brain expressed X-linked/transcription elongation factor A (SII) (BEX/TCEAL) family members, that is downregulated in trisomy. At the same time, trisomic cells showed a significantly increased expression of non-coding X-inactive specific transcript (XIST), responsible for the X-chromosome inactivation. Importantly, the dysregulation of BEX/TCEAL is linked to psychiatric disorders, intellectual deficits, neurodegeneration, and AD. Noticeably, other recent studies, including those performed in DS cell lines and human postmortem brains, showed downregulated expression of different genes in this cluster accompanied by enhanced XIST levels. However, the aberrant expression of these transcription factors and their potential connection to brain pathology in trisomy has been neglected. Herein, we hypothesize that downregulation of BEX/TCEAL is causatively related to abnormal brain development and AD pathology in DS. In our studies, we will determine the contribution of X-chromosome-linked genes’ repression to DS-related pathology by assessing whether reducing XIST or restoring BEX/TCEAL gene expression can mitigate DS-associated cellular phenotypes. We will specifically focus on the effect of BEX2 and TCEAL7 downregulation in DS since their expression was most consistently downregulated across multiple developmental periods in DS human transcriptomic study, further supporting our preliminary data. We will also define the genome-wide downstream targets of BEX2 and TCEAL7 and their significance in trisomy. Our translational, human-directed study will ultimately test the causative link between the dysregulation of X- chromosome-linked genes’, and transcriptional and phenotypical alterations in trisomy.

抽象的 唐氏综合症 (DS) 是由人类 21 号染色体 (HSA21) 三倍体引起，导致 智力障碍、运动功能障碍和早发性阿尔茨海默病 (AD)。这 DS 中的三倍基因与 DS 中全面不平衡之间的机制联系 DS 脑细胞异常背后的基因表达尚未确定。它 还不清楚这种全球转录组失衡如何导致智力障碍和早期 DS 中 AD 相关病理的发展，以及哪些基因在这些过程中发挥关键作用。 在我们的初步研究中，我们生成了源自 DS 的寡皮质球体 (OLS) 等基因诱导多能干细胞（iPSC）系。三体 OLS 概括 DS 和 AD- 相关的细胞表型，包括皮质体积减少、髓鞘形成异常和 β 淀粉样蛋白和过度磷酸化 tau 蛋白的病理沉积。通过我们的单细胞 对整倍体和三体 OLS 进行 RNA 测序 (scRNA-seq) 分析，我们发现了一组 X- 含有脑表达 X 连锁/转录延伸因子 A (SII) 的连锁基因 (BEX/TCEAL) 家族成员，在三体性中下调。与此同时，三体细胞 显示非编码 X 失活特异性转录物 (XIST) 的表达显着增加， 负责 X 染色体失活。重要的是，BEX/TCEAL 的失调是 与精神疾病、智力缺陷、神经退行性疾病和AD有关。值得注意的是，其他 最近的研究，包括在 DS 细胞系和人类死后大脑中进行的研究表明 该簇中不同基因的表达下调，同时 XIST 增强 水平。然而，这些转录因子的异常表达及其潜力 三体性与大脑病理学的联系被忽视了。在此，我们假设 BEX/TCEAL 的下调与大脑发育异常和 DS 中的 AD 病理。在我们的研究中，我们将确定 X 染色体连锁的贡献 通过评估是否减少 XIST 或恢复基因对 DS 相关病理的抑制 BEX/TCEAL 基因表达可以减轻 DS 相关的细胞表型。我们将 特别关注 BEX2 和 TCEAL7 下调在 DS 中的影响，因为它们的表达 在 DS 人类的多个发育时期最一致地下调 转录组研究，进一步支持我们的初步数据。我们还将定义全基因组 BEX2 和 TCEAL7 的下游靶标及其在三体性中的意义。我们的翻译， 以人为本的研究最终将测试 X- 失调之间的因果关系 染色体连锁基因，以及三体性的转录和表型改变。