Yang Shaling, Feng Yuting, Gao Wenxia, Wang Jia, Liu Yonghua, Feng Jinrong
Department of Pathogen Biology, School of Medicine, Nantong University, Nantong, Jiangsu 226001, China.
Department of Clinical Laboratory, Kunshan Hospital of Chinese Medicine, Kunshan, Jiangsu 215300, China.
Cell Signal. 2025 Oct;134:111931. doi: 10.1016/j.cellsig.2025.111931. Epub 2025 Jun 7.
Precise DNA replication is essential for maintaining genomic stability, ensuring cellular homeostasis and faithful genetic transmission. Nevertheless, intrinsic and extrinsic factors frequently compromise replication fidelity, leading to replication stress-induced genomic instability, a potential contributor to pathogen virulence. In the fungal pathogen Candida albicans, the global transcriptomic adaptations underpinning the replication stress response and their potential contributions to fungal pathogenicity remain poorly understood. This study employed genome-wide RNA sequencing to map transcriptome dynamics in C. albicans exposed to hydroxyurea (HU), which induces DNA replication stress. Our analysis revealed significant transcriptional reprogramming under HU treatment, identifying 565 differentially expressed genes (DEGs) enriched in DNA replication/repair, cell cycle, oxidoreductase activity, lyase function, and cofactor binding. Notably, HNV1 (Orf19.4872), a previously uncharacterized gene, exhibited robust induction by HU, methyl methanesulfonate (MMS), and H₂O₂. Functional characterization demonstrated that HNV1 deletion conferred enhanced resistance to oxidative stress and hypervirulence in both Galleria mellonella and murine systemic infection models. Mechanistically, Hnv1 functions as a negative regulator of virulence by suppressing extracellular protease secretion through upregulation of SAP4, SAP5 and SAP6, while also modulating antioxidant defense pathways (e.g., CAT1, FDH1, HPD1). CRISPRi-mediated repression of these antioxidant genes reversed the hypervirulent phenotype. Collectively, this work identifies Hnv1 as a critical hub linking DNA replication stress to redox homeostasis and virulence in C. albicans, providing new mechanistic insights into fungal pathogenesis.
精确的DNA复制对于维持基因组稳定性、确保细胞内稳态和忠实的遗传传递至关重要。然而，内在和外在因素经常损害复制保真度，导致复制应激诱导的基因组不稳定，这是病原体毒力的一个潜在因素。在真菌病原体白色念珠菌中，支撑复制应激反应的全球转录组适应性及其对真菌致病性的潜在贡献仍知之甚少。本研究采用全基因组RNA测序来绘制暴露于羟基脲（HU）的白色念珠菌中的转录组动态，羟基脲可诱导DNA复制应激。我们的分析揭示了HU处理下显著的转录重编程，鉴定出565个差异表达基因（DEG），这些基因富集于DNA复制/修复、细胞周期、氧化还原酶活性、裂解酶功能和辅因子结合。值得注意的是，HNV1（Orf19.4872），一个以前未被表征的基因，在HU、甲磺酸甲酯（MMS）和H₂O₂处理下表现出强烈的诱导作用。功能表征表明，在大蜡螟和小鼠全身感染模型中，HNV1缺失赋予了对氧化应激的增强抗性和高毒力。从机制上讲，Hnv1通过上调SAP4、SAP5和SAP6来抑制细胞外蛋白酶分泌，从而作为毒力的负调节因子，同时还调节抗氧化防御途径（如CAT1、FDH1、HPD1）。CRISPRi介导的这些抗氧化基因的抑制逆转了高毒力表型。总之，这项工作将Hnv1确定为连接白色念珠菌中DNA复制应激与氧化还原稳态和毒力的关键枢纽，为真菌发病机制提供了新的机制见解。
