The Role of NFAT5 in Immune Response and Antioxidant Defense in the Thick-Shelled Mussel (Mytilus coruscus).

Abstract

Nuclear Factor of Activated T Cells 5 (NFAT5) is a transcription factor that plays a pivotal role in immune regulation. While its functions have been extensively studied in mammalian immune systems, its role in marine invertebrates, particularly in bivalves, remains largely unexplored. This study provides the first characterization of the NFAT5 gene in the thick-shelled mussel (Mytilus coruscus), investigating its evolutionary characteristics and immunological functions. Using direct RNA sequencing, McNFAT5 was comprehensively analyzed, revealing its critical involvement in the innate immune response of M. coruscus to Vibrio alginolyticus challenge. Differential expression patterns of McNFAT5 were observed across various tissues with the highest expression detected in hemolymphs. The knockdown of McNFAT5 using small interfering RNA (siRNA) led to a significant reduction in the activities of superoxide dismutase (SOD), Na⁺/K⁺-ATPase, and antioxidant enzymes compared to levels observed post-infection. These findings highlight the central role of McNFAT5 in modulating antioxidant defense mechanisms. In conclusion, McNFAT5 is a key regulatory factor in the innate immune system of M. coruscus, providing valuable insights into the immune adaptive mechanisms and evolutionary mechanisms of bivalve immunity. This study contributes to a deeper understanding of the immune regulatory networks in marine invertebrates.