全基因组组蛋白修饰和CTCF富集预测绵羊巨噬细胞中的基因表达

Genome-Wide Histone Modifications and CTCF Enrichment Predict Gene Expression in Sheep Macrophages.

作者信息

Massa Alisha T, Mousel Michelle R, Herndon Maria K, Herndon David R, Murdoch Brenda M, White Stephen N

机构信息

Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, United States.

Animal Disease Research Unit, Agricultural Research Service, United States Department of Agriculture, Pullman, WA, United States.

出版信息

Front Genet. 2021 Jan 7;11:612031. doi: 10.3389/fgene.2020.612031. eCollection 2020.

Abstract

Alveolar macrophages function in innate and adaptive immunity, wound healing, and homeostasis in the lungs dependent on tissue-specific gene expression under epigenetic regulation. The functional diversity of tissue resident macrophages, despite their common myeloid lineage, highlights the need to study tissue-specific regulatory elements that control gene expression. Increasing evidence supports the hypothesis that subtle genetic changes alter sheep macrophage response to important production pathogens and zoonoses, for example, viruses like small ruminant lentiviruses and bacteria like . Annotation of transcriptional regulatory elements will aid researchers in identifying genetic mutations of immunological consequence. Here we report the first genome-wide survey of regulatory elements in any sheep immune cell, utilizing alveolar macrophages. We assayed histone modifications and CTCF enrichment by chromatin immunoprecipitation with deep sequencing (ChIP-seq) in two sheep to determine regulatory DNA elements and chromatin domain boundaries that control immunity-related gene expression. Histone modifications included H3K4me3 (denoting active promoters), H3K27ac (active enhancers), H3K4me1 (primed and distal enhancers), and H3K27me3 (broad silencers). In total, we identified 248,674 reproducible regulatory elements, which allowed assignment of putative biological function in macrophages to 12% of the sheep genome. Data exceeded the FAANG and ENCODE standards of 20 million and 45 million useable fragments for narrow and broad marks, respectively. Active elements showed consensus with RNA-seq data and were predictive of gene expression in alveolar macrophages from the publicly available Sheep Gene Expression Atlas. Silencer elements were not enriched for expressed genes, but rather for repressed developmental genes. CTCF enrichment enabled identification of 11,000 chromatin domains with mean size of 258 kb. To our knowledge, this is the first report to use immunoprecipitated CTCF to determine putative topological domains in sheep immune cells. Furthermore, these data will empower phenotype-associated mutation discovery since most causal variants are within regulatory elements.

摘要

肺泡巨噬细胞在先天性和适应性免疫、伤口愈合以及肺部稳态中发挥作用,这依赖于表观遗传调控下的组织特异性基因表达。尽管组织驻留巨噬细胞具有共同的髓系谱系,但其功能多样性凸显了研究控制基因表达的组织特异性调控元件的必要性。越来越多的证据支持这样一种假说,即细微的基因变化会改变绵羊巨噬细胞对重要生产病原体和人畜共患病原体的反应,例如,像小反刍兽疫病毒这样的病毒以及像……这样的细菌。转录调控元件的注释将有助于研究人员识别具有免疫后果的基因突变。在此,我们报告了首次利用肺泡巨噬细胞对任何绵羊免疫细胞中的调控元件进行全基因组范围的调查。我们通过染色质免疫沉淀结合深度测序(ChIP-seq)在两只绵羊中检测组蛋白修饰和CTCF富集情况,以确定控制免疫相关基因表达的调控DNA元件和染色质结构域边界。组蛋白修饰包括H3K4me3(表示活跃启动子)、H3K27ac(活跃增强子)、H3K4me1(起始和远端增强子)以及H3K27me3(广泛沉默子)。我们总共鉴定出248,674个可重复的调控元件,这使得能够将巨噬细胞中的假定生物学功能赋予绵羊基因组的12%。数据分别超过了FAANG和ENCODE标准,窄标记和宽标记的可用片段分别为2000万和4500万。活跃元件与RNA-seq数据一致,并能预测来自公开可用的绵羊基因表达图谱中肺泡巨噬细胞的基因表达。沉默元件在表达基因中不富集,而是在受抑制的发育基因中富集。CTCF富集使得能够鉴定出11,000个染色质结构域,平均大小为258 kb。据我们所知,这是第一份使用免疫沉淀的CTCF来确定绵羊免疫细胞中假定拓扑结构域的报告。此外,由于大多数因果变异位于调控元件内,这些数据将有助于发现与表型相关的突变。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/805d/7817998/c551f1b4c36e/fgene-11-612031-g001.jpg

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