Functional Intronic Variant in the Retinoblastoma 1 Gene Underlies Broiler Chicken Adiposity by Altering Nuclear Factor-kB and SRY-Related HMG Box Protein 2 Binding Sites

The present study aimed to search
for chicken abdominal fat deposition-related
polymorphisms within RB1 and to provide functional
evidence for significantly associated genetic variants. Association
analyses showed that 11 single nucleotide polymorphisms (SNPs) in
intron 17 of RB1, were significantly associated with
both abdominal fat weight (P < 0.05) and abdominal
fat percentage (P < 0.05). Functional analysis
revealed that the A allele of g.32828A>G repressed
the transcriptional efficiency of RB1 in vitro, through
binding nuclear factor-kappa B (NF-KB) and SRY-related
HMG box protein 2 (SOX2). Furthermore, RB1 mRNA expression
levels in the abdominal fat tissue of individuals with the A/A genotype of g.32828A>G were lower than those of individuals
with the G/G genotype. Collectively, we propose that
the intronic SNP g.32828A>G of RB1 is an obesity-associated
variant that directly affects binding with NF-KB and SOX2,
leading to changes in RB1 expression which in turn
may influence chicken abdominal fat deposition.