Nuclear factor of activated T cells 5 (NFAT5) is an osmosensitive transcription factor that is well-studied in renal but rarely explored in cardiac diseases. Although the association of Coxsackievirus B3 (CVB3) with viral myocarditis is well-established, the role of NFAT5 in this disease remains largely unexplored. Previous research has demonstrated that NFAT5 restricts CVB3 replication yet is susceptible to cleavage by CVB3 proteases. Using an inducible cardiac-specific Nfat5-knockout mouse model, we uncovered that NFAT5-deficiency exacerbates cardiac pathology, worsens cardiac function, elevates viral load, and reduces survival rates. RNA-seq analysis of CVB3-infected mouse hearts revealed the significant impact of NFAT5-deficiency on gene pathways associated with cytokine signaling and inflammation. Subsequent in vitro and in vivo investigation validated the disruption of the cytokine signaling pathway in response to CVB3 infection, evidenced by reduced expression of key cytokines such as interferon β1 (IFNβ1), C–X–C motif chemokine ligand 10 (CXCL10), interleukin 6 (IL6), among others. Furthermore, NFAT5-deficiency hindered the formation of stress granules, leading to a reduction of important stress granule components, including plakophilin-2, a pivotal protein within the intercalated disc, thereby impacting cardiomyocyte structure and function. These findings unveil a novel mechanism by which NFAT5 inhibits CVB3 replication and pathogenesis through the promotion of antiviral type I interferon signaling and the formation of cytoplasmic stress granules, collectively identifying NFAT5 as a new cardio protective protein.

活化 T 细胞核因子 5 （NFAT5） 是一种渗透敏感的转录因子，在肾脏中得到了充分研究，但在心脏病中很少探索。尽管柯萨奇病毒 B3 （CVB3） 与病毒性心肌炎的相关性已得到充分证实，但 NFAT5 在这种疾病中的作用在很大程度上仍未得到探索。先前的研究表明，NFAT5 限制 CVB3 复制，但易被 CVB3 蛋白酶切割。使用可诱导的心脏特异性 Nfat5 敲除小鼠模型，我们发现 NFAT5 缺陷会加剧心脏病变，恶化心脏功能，提高病毒载量，并降低存活率。CVB3 感染小鼠心脏的 RNA-seq 分析揭示了 NFAT5 缺陷对与细胞因子信号传导和炎症相关的基因通路的显着影响。随后的体外和体内研究验证了响应 CVB3 感染的细胞因子信号通路的破坏，干扰素 β 1 （IFNβ1）、C-X-C 基序趋化因子配体 10 （CXCL10）、白细胞介素 6 （IL6） 等关键细胞因子的表达降低证明了这一点。此外，NFAT5 缺陷阻碍了应激颗粒的形成，导致重要的应激颗粒成分减少，包括 plakophilin-2，一种嵌入盘内的关键蛋白，从而影响心肌细胞的结构和功能。这些发现揭示了 NFAT5 通过促进抗病毒 I 型干扰素信号传导和细胞质应激颗粒的形成来抑制 CVB3 复制和发病机制的新机制，共同将 NFAT5 确定为一种新的心脏保护蛋白。