Characterization and Functional Analysis of Trim38 in the Immune Response of the Large Yellow Croaker (Larimichthys crocea) Against Pseudomonas plecoglossicida Infection

The large yellow croaker (<i>Larimichthys crocea</i>) is a cornerstone species in Chinese marine aquaculture, yet bacterial infections-particularly visceral white nodules disease (VWND) caused by <i>Pseudomonas plecoglossicida</i>-severely compromise its production. This study aimed to elucidate the immunoregulatory mechanisms of tripartite motif-containing protein 38 in the large yellow croaker (<i>Lctrim38</i>) during bacterial infections, with an emphasis on host-pathogen interactions involving <i>P. plecoglossicida</i>, to evaluate its potential for disease-resistant breeding applications. The full-length cDNA of <i>Lctrim38</i> was cloned and characterized, with structural analysis revealing a conserved domain architecture comprising RING, B-box, coiled-coil, and PRY-SPRY motifs. Functional characterization through <i>Lctrim38</i> overexpression in large yellow croaker kidney cells (PCK cells) demonstrated significant modulation of key immune-related pathways, including TGF-β, PI3K-Akt, IL-17, and PPAR. Notably, <i>Lctrim38</i>-mediated inhibition of NF-κB signaling was shown to downregulate pro-inflammatory cytokines (TNF-α, IL-6, IFN-γ), establishing its role as a negative regulator of inflammatory responses. These findings provide insights into the immune mechanisms of Trim38 in large yellow croakers and highlight its potential as a molecular target for disease resistance breeding. Future research should explore its broader functions, including its antiviral potential.