Large-scale Single-nuclei Profiling Identifies Role for ATRNL1 in Atrial Fibrillation [snRNA-seq]. Large-scale Single-nuclei Profiling Identifies Role for ATRNL1 in Atrial Fibrillation [snRNA-seq]

Atrial fibrillation (AF) is the most common sustained arrhythmia in humans, yet the molecular basis of AF remains incompletely understood. To determine the cell type-specific transcriptional changes underlying AF, we performed single-nucleus RNA-seq (snRNA-seq) on age- and sex-matched left atrial (LA) samples from 18 patients with AF and 16 controls without AF. From more than 175,000 nuclei we identified 15 cell types but found that only cardiomyocytes (CMs) and macrophages (MΦs) had a significant number of differentially expressed genes in patients with AF. Attractin Like 1 (ATRNL1) was strongly overexpressed in CMs among patients with AF and localized to the intercalated discs. Further, in both knockdown and overexpression experiments in atrial human embryonic stem cell-derived CMs (hESC-aCMs) we identified a potent role for ATRNL1 in cell stress response, cardiac conduction, cell junction organization and in modulation of the cardiac action potential. Finally, we prioritized genes at the known genetic loci for AF and identified an unexpected expression for a leading AF candidate gene, KCNN3. In sum, we have identified a role for ATRNL1 and other differentially regulated genes that may serve as potential therapeutic targets for this common arrhythmia. Overall design: To characterize the cellular and molecular characteristics associated with AF, we performed snRNA-seq on samples from the LA of human patients with AF who were not in heart failure (n=19) as well as non-AF controls (n=19).

心房颤动（Atrial Fibrillation, AF）是人类最常见的持续性心律失常，但其分子机制仍未完全阐明。为明确AF发生的细胞类型特异性转录变化，我们对18例AF患者及16例年龄、性别匹配的非AF对照者的左心房（left atrial, LA）样本开展了单细胞核RNA测序（single-nucleus RNA-seq, snRNA-seq）。从超过17.5万个细胞核中，我们鉴定出15种细胞类型，但仅发现心肌细胞（cardiomyocytes, CMs）和巨噬细胞（macrophages, MΦs）在AF患者中存在显著数量的差异表达基因。

吸引素样1（Attractin Like 1, ATRNL1）在AF患者的心肌细胞中显著高表达，并定位于闰盘（intercalated discs）。进一步，在人类胚胎干细胞来源的心房心肌细胞（human embryonic stem cell-derived CMs, hESC-aCMs）的敲低与过表达实验中，我们证实ATRNL1在细胞应激反应、心脏传导、细胞连接组装及心脏动作电位调控中发挥关键作用。最后，我们对已知AF遗传位点的基因进行优先级排序，意外发现AF核心候选基因KCNN3存在异常表达。

综上，我们明确了ATRNL1及其他差异调控基因的功能，这些基因或可作为该常见心律失常的潜在治疗靶点。

整体实验设计：为表征与AF相关的细胞及分子特征，我们对19例无心力衰竭的AF患者及19例非AF对照者的左心房样本开展了snRNA-seq实验。