Identification of a novel N4BP1-like gene from grass carp (Ctenopharyngodon idella) in response to GCRV infection

• One novel N4BP1 gene was cloned from Ctenopharyngodon idella.
• The mRNA expression of CiN4BP1 gene responded to GCRV infection.
• CiN4BP1 overexpression decreased viral gene transcription.

Nedd4 binding protein 1 (N4BP1) has been identified as an interacting protein and a substrate of Nedd4 E3 ligase. However, the report about N4BP1's function is limit. In this study, a novel N4BP1 gene (CiN4BP1) was cloned from grass carp (Ctenopharyngodon idella). The full-length cDNA sequence of CiN4BP1 (3022 bp) included an open reading frame (ORF) of 2565 bp, which encoded a putative peptides of 854 amino acids containing one KH domain and one NYN domain. It was close homology (47% identify) to Oryzias latipes N4BP1. And mRNA expression of CiN4BP1 gene showed relatively high level in skin, gill, head kidney and spleen. After grass carp reovirus (GCRV) infection, CiN4BP1 was up-regulated in vivo and in vitro. Furthermore, overexpression of CiN4BP1 in CIK cells inhibited viral gene transcription. These data indicated that CiN4BP1 might play an important role in immune response to viral invasion.