Genome-transcriptome co-analysis identifies members and molecular characteristics of the TRAF gene family in Siberian sturgeon (Acipenser baerii)

Tumor necrosis factor receptor-associated factors (TRAFs), as key signal transducers, play a crucial role in both innate and adaptive immune responses. However, current research on the systematic identification of the TRAF family and its functional role in Siberian sturgeon (Acipenser baerii) is relatively unexplored. In this study, TRAF family members were first identified in A. baerii using comparative genomics and transcriptome analyses. To further determine the TRAF sequences of A. baerii, the open reading frame (ORF) sequences of the Abtraf1, Abtraf5, Abtraf6, and Abtraf7 were cloned. Bioinformatics analysis revealed that these Abtraf exhibit high sequence similarity and evolutionary conservation across teleost species. RNA-seq and qRT-PCR analysis revealed high Abtraf expression in the whole pre-larvae stage and immune-related tissues such as the head kidney, gill, and spleen. Induction of Abtraf gene expression was observed upon stimulation with Streptococcus iniae and Aeromonas hydrophila in vivo. In this study, head kidney leukocytes (HKLs) were isolated and stimulated with lipopolysaccharide (LPS), peptidoglycan (PGN), or poly(I:C), all of which induced Abtraf expression, with significant upregulation occurring early post-treatment. Notably, Abtraf5 responded predominantly to bacterial components (LPS/PGN), whereas Abtraf7 was specifically poly(I:C)-responsive. These findings help clarify the molecular roles of Abtraf and provide a basis for further functional research on TRAF in teleosts.