Cloning and characterization of a COMMD4 gene from amphioxus (Branchiostoma belcheri): an insight into the function and evolution of COMMD4.

The recently discovered COMM domain-containing (COMMD) protein family has ten members (COMMD1-10). A COMMD protein contains a carboxyl-terminal COMM (copper metabolism gene MURR1) domain which provides an interface for protein-protein interactions. However, no COMMD4 gene has been identified in amphioxus. In this study, we report the identification and characterization of a COMMD4 gene from the amphioxus (designated as AmphiCOMMD4). First, we cloned the full length of AmphiCOMMD4 gene and found that the deduced amino acid sequence of AmphiCOMMD4 has 55.5-82.5% similarity and 38.8-64.0% identity to those from other species. Second, the genomic structure analysis of AmphiCOMMD4 gene showed that COMMD4 underwent intron loss in amphioxus. Third, we found that the AmphiCOMMD4 was ubiquitously and differentially expressed in five investigated tissues (muscles, gills, intestine, hepatic cecum and gonad). Finally, we found that the expression level of AmphiCOMMD4 gene was induced by LPS stimulation. In conclusion, our study elaborates the COMMD4 in amphioxus and provides an insight into the innate immunity and the evolution of the COMMD family.