RNase H2, mutated in Aicardi‐Goutières syndrome, resolves co-transcriptional R-loops to prevent DNA breaks and inflammation.

RNase H2 is a specialized enzyme that degrades RNA in RNA/DNA hybrids and deficiency of this enzyme causes a severe neuroinflammatory disease, Aicardi Goutières syndrome (AGS). However, the molecular mechanism underlying AGS is still unclear. Here, we show that RNase H2 is associated with a subset of genes, in a transcription-dependent manner where it interacts with RNA Polymerase II. RNase H2 depletion impairs transcription leading to accumulation of R-loops, structures that comprise RNA/DNA hybrids and a displaced DNA strand, mainly associated with short and intronless genes. Importantly, accumulated R-loops are processed by XPG and XPF endonucleases which leads to DNA damage and activation of the immune response, features associated with AGS. Consequently, we uncover a key role for RNase H2 in the transcription of human genes by maintaining R-loop homeostasis. Our results provide insight into the mechanistic contribution of R-loops to AGS pathogenesis. In Hela cells: ChIP-seq of RNaseH2A and RNA polymerase II, DRIP-seq -/+ RNaseH after siLuc or siRNaseH2A, and chromatin RNA-seq after siLuc or siRNAseH2A.

核糖核酸酶H2（RNase H2）是一类特异性降解RNA/DNA杂交链中RNA的酶，该酶的功能缺陷可引发重症神经炎症性疾病——艾卡迪-古特雷斯综合征（Aicardi Goutières syndrome, AGS）。然而，该病的分子致病机制至今仍不明确。本研究发现，核糖核酸酶H2以转录依赖的方式与RNA聚合酶II（RNA Polymerase II）相互作用，并结合部分基因子集。敲低核糖核酸酶H2会损害转录进程，进而导致R环（R-loops）的积累——这类结构由RNA/DNA杂交链与一条被置换的DNA单链构成，且主要分布于短小且不含内含子的基因区域。值得注意的是，积累的R环会被XPG与XPF核酸内切酶切割加工，进而引发DNA损伤与免疫应答激活，这些病理特征均与AGS的发病相关。据此，我们揭示了核糖核酸酶H2通过维持R环稳态，在人类基因转录过程中发挥的关键调控作用。本研究结果为阐明R环在AGS发病机制中的作用提供了重要的理论依据。本数据集源自海拉细胞（Hela cells），包含以下测序数据：核糖核酸酶H2A（RNaseH2A）与RNA聚合酶II的染色质免疫沉淀测序（ChIP-seq）、经siLuc或siRNaseH2A处理后添加/未添加核糖核酸酶H的DNA-RNA杂交免疫沉淀测序（DRIP-seq），以及经siLuc或siRNaseH2A处理后的染色质RNA测序（chromatin RNA-seq）。