Molecular characterization of a CpTRIM35-like protein and its splice variants from whitespotted bamboo shark (Chiloscyllium plagiosum)

• A TRIM gene and three splice variants were firstly cloned from elasmobranch fish.
• The genes were constitutively expressed with high levels in spleen and kidney.
• The gene products were distributed in cytoplasm alone or cytoplasm and nucleus.
• As E3 ubiquitin ligases, the proteins differed in immune responses to challenges.

The tripartite motif (TRIM) proteins play important roles in a broad range of biological processes, including apoptosis, cell proliferation and innate immunity response. In this study, a TRIM gene and its three splice variants were cloned from an elasmobranch fish—whitespotted bamboo shark (Chiloscyllium plagiosum Bennett). Phylogenetic analysis indicated that the gene was closely related to TRIM35 homologs, thus termed CpTRIM35-like. Deduced CpTRIM35 has a RBCC-PRY/SPRY structure typical of TRIM proteins, and its splice variants (CpTRIM35-1–3) have different truncations at the C-terminus. The gene products were constitutively expressed in adult sharks with the highest levels in spleen and kidney. The different subcellular locations, upregulation upon LPS and poly I:C stimulation, and significant E3 ubiquitin ligase activities suggested their different roles in immune responses as an E3 ubiquitin ligase. This is the first TRIM protein ever characterized in elasmobranch fish.