Key Promoter Region of Wnt4 response to FSH and Genetic Effect on Several Production Traits of Its Mutations in Chicken

The signaling pathway of the wingless-type mouse mammary tumor virus integration site (Wnt) plays an important role in ovarian and follicular development. Wnt4 was shown in our previous study to be involved in the selection and development of chicken follicles by up-regulating the expression of follicle stimulating hormone receptors ( FSHR ), stimulating the proliferation of follicular granulosa cells and increasing the secretion of steroidal hormones. To further characterize cis-elements regulating chicken Wnt4 transcription, in this study we determined critical regulatory regions affecting chicken Wnt4 transcription, then identified a single nucleotide polymorphism (SNP) in this region, and finally analyzed the association of the SNP with chicken production traits. The results showed that the 5′ regulatory region from -3354 to -2689 of the chicken Wnt4 gene had the strongest activity and greatest response to FSH stimulation, and that one SNP site -3015 (G > C) in this segment was identified as affecting the binding of NFAT5 (nuclear factor of activated T cells 5). When G was replaced by C at this site, it eliminated the binding by NFAT5. Moreover, this locus was significantly associated with the keel length and comb length of hens. Individuals with the genotype CG had longer keels while those with genotype CC had longer combs. Collectively, these data suggested that the SNP-3015 (G > C) is (i) involved in the regulation of Wnt4 gene expression by affecting the binding of NFAT5, (ii) associated with chicken keel length and comb length, and (iii) is a potential DNA marker in the molecular breeding of chickens for egg laying.