Abstract

The tripartite motif (TRIM) protein family functions as a crucial regulator of innate immunity; however, the specific roles of these proteins in crustaceans remain largely uncharacterized. This study characterizes a novel TRIM37 homolog ( Es TRIM37) in the Chinese mitten crab, Eriocheir sinensis . Sequence analysis revealed that EsTRIM37 encodes a 936-amino acid protein containing conserved RING, B-box, BBC, and MATH domains. Quantitative real-time PCR showed that EsTRIM37 is constitutively expressed in all examined tissues, with highest abundance in hemocytes, and is significantly upregulated following challenge with Staphylococcus aureus or Vibrio parahaemolyticus . RNA interference (RNAi)-mediated knockdown of Es TRIM37 severely impaired antibacterial defense in vivo , resulting in increased bacterial burdens and significantly reduced host survival rates. Mechanistically, Es TRIM37 silencing inhibited the nuclear translocation of the transcription factors Dorsal and Relish, key components of the Toll and IMD pathways, respectively. Consequently, the expression of multiple downstream antimicrobial peptides (AMPs) was downregulated. These findings collectively demonstrate that Es TRIM37 acts as an essential positive regulator of antibacterial immunity in E. sinensis , enhancing AMPs production and bacterial clearance.