Growth-Associated SNPs of the NCAPG-LCORL Locus and Divergent Functions of NCAPG and LCORL in Chicken SMSCs.

Body weight (BW) serves as a core indicator for evaluating chicken growth performance and implementing early individual selective breeding. Our previous studies have verified that 8-week body weight (BW8) exhibits a significantly positive correlation with body weights at 10 and 12 weeks of age in chickens, implying that early body weight can be used to predict late growth phenotypes; nevertheless, the underlying genetic regulatory mechanisms remain elusive. Multiple investigations on growth traits of livestock have confirmed that the NCAPG-LCORL locus acted as a critical candidate interval associated with growth-related traits. In the present study, an F2 segregating population derived from the cross of Gushi chickens and Anka broilers was used as experimental material. Single-nucleotide polymorphism (SNP) screening within the NCAPG-LCORL locus was performed based on GBS data, followed by the LD analysis. A total of eight SNPs were identified to be significantly associated with economic growth traits in chickens, including four tag SNPs and four non-tag SNPs. In vitro functional validation using chicken skeletal muscle satellite cells (SMSCs) revealed functional divergence between NCAPG and LCORL during myocyte development: NCAPG facilitated SMSCs proliferation while repressing SMSCs differentiation, whereas LCORL exerted positive regulatory effects on both proliferation and differentiation of SMSCs. Collectively, NCAPG modulates whole-body chicken growth by remodeling the dynamic balance between proliferation and differentiation of skeletal muscle satellite cells. In contrast, LCORL simultaneously promotes myocyte proliferation and differentiation to accelerate skeletal muscle development, thereby enhancing chicken growth performance. This study elucidates the regulatory roles of the NCAPG-LCORL locus in chicken growth at both the molecular marker and cellular functional levels, laying a theoretical foundation for marker-assisted selection of growth traits in chicken breeding.