A novel candidate gene CLN8 regulates fat deposition in avian

Abstract

Background The fat deposition has a crucial role in animal meat flavor, and fat deposition-related traits are vital for breeding in the commercial duck industry. Avian fat-related traits are typical complex phenotypes, which need a large amount of data to analyze the genetic loci. Results In this study, we newly phenotyped fat traits and genotyped whole-genome variations for 1246 ducks, and combed with previous GWAS data to reach 1880 ducks for following analysis. The carcass composition traits, subcutaneous fat weight (SFW), subcutaneous fat percentage (SFP), Abdominal fat weight (AFW), Abdominal fat percentage (AFP) and the body weight of day 42 (BW42) for each duck were collected. We identified a set of new loci that affect the traits related to fat deposition in avian. Among these loci, Ceroid-lipofuscinosis, neuronal 8 (CLN8) is a novel candidate gene controlling fat deposition. We investigated its novel function and regulation in avian adipogenesis.Five significant SNPs and a single haplotype were detected in the upstream of gene CLN8 and the most significant SNP (P-value = 21.37E-12) for subcutaneous fat percentage was obtained. Subsequently, luciferase assay demonstrated that five linkage mutations in the upstream of the CLN8 gene significantly decreased the transcriptional activity of CLN8. Further, ATAC-seq analysis showed that transcription factor binding sites were identified in a region close to the haplotype. A set of luciferase reporter gene vectors that contained different deletion fragments of the CLN8 promoter were constructed, and the core promoter area of CLN8 was finally identified in the − 1884/-1207 bp region of the 5′ flanking sequences, which contains adipogenesis-related transcription factors binding sites. Moreover, the over-expression of CLN8 can remarkably facilitate adipocyte differentiation in ICPs. Consistent with these, the global transcriptome profiling and functional analysis of the over-expressed CLN8 in the cell line further revealed that the lipid biosynthetic process during the adipogenesis was significantly enriched. Conclusions Our results demonstrated that CLN8 is a positive regulator of avian adipocyte differentiation. These findings identify a novel function of CLN8 in adipocyte differentiation, which provides important clues for the further study of the mechanism of avian fat deposition.