From Multi-Omics to Mechanism: Nucleocapsid–RCHY1–JUNB Axis Underlies SARS-CoV-2 Related Atrial Fibrillation Vulnerability
Chengyu Xiang, Yeqian Zhu, Wei Zhao, Pengcheng Zhao, Yan Hua, Ruijie Xu, Youfu Huang, Albrecht Von Brunn, Dingguo Zhang, Fengxiang ZhangAbstract
Background and Aims
SARS-CoV-2 exposure has been linked to cardiovascular complications, including atrial fibrillation (AF), but the host pathways coupling viral factors to atrial remodeling and AF vulnerability remain incompletely understood.
Methods
We integrated multi-cohort human transcriptomes from SARS-CoV-2–infected cardiac models and AF tissues, applied WGCNA and machine-learning–based feature selection, and profiled immune infiltration. To approximate a sustained low-grade inflammatory milieu relevant to prolonged COVID-19-related cardiovascular sequelae, mice with cardiac SARS-CoV-2 N expression underwent repeated low-dose LPS administration. JUNB loss-of-function was evaluated by rAAV9-mediated cardiac knockdown, with echocardiographic, electrophysiological, histological, and molecular phenotyping. Mechanistic studies were performed in modified cardiomyocytes.
Results
Integrated transcriptomic analyses identified JUNB as a shared hub associated with SARS-CoV-2-related cardiac signaling and AF, with enrichment of inflammatory pathways relevant to atrial remodeling. In the chronic inflammatory model, cardiac N expression exacerbated atrial enlargement, inflammatory-fibrotic remodeling, AF inducibility and duration, and AERP shortening, whereas cardiac JUNB knockdown attenuated these changes. Mechanistically, co-immunoprecipitation and in-cell ubiquitination assays showed that SARS-CoV-2 N enhanced the JUNB-RCHY1 interaction, promoting K63-linked ubiquitination and stabilizing JUNB. Site-mapping and functional assays identified K36 as the dominant ubiquitination site required for N-driven JUNB stabilization, TNF-α/NF-κB activation, and downstream inflammatory and fibrotic gene programs.
Conclusion
Cardiac SARS-CoV-2 N protein promotes atrial inflammatory-fibrotic remodeling and AF vulnerability under chronic inflammatory conditions relevant to post-acute or prolonged COVID-19-related cardiovascular sequelae through RCHY1-dependent ubiquitination and stabilization of JUNB, identifying the N-RCHY1-JUNB axis as a mechanistically defined pathway for future therapeutic investigation.