Identification of key module and hub genes affecting broiler body weight through weighted gene co-expression network analysis.

Body weight (BW) is an important economic trait in chickens. The hypothalamus serves as a central regulator of appetite and energy balance, and extensive research has demonstrated its pivotal role in regulating BW. However, the molecular network of the hypothalamus regulating BW traits in chickens needs to be further illuminated. In the present study, 200 1-day-old male 817 broilers were reared to 50 d of age, and BW were recorded. 20 birds with the lowest BW were classified as the low body weight group (L-BWG), and 20 birds with the highest BW were classified as the high body weight group (H-BWG). 18 hypothalamic tissue samples were collected, including 5 from the L-BWG, 5 from the H-BWG, and 8 from the middle weight range, and were analyzed using RNA-seq and weighted gene co-expression network analysis (WGCNA). Among the 18 RNA-seq samples, 5 samples from the L-BWG and 5 from the H-BWG were selected for differential expression gene analysis. Compared with the L-BWG, 195 and 1,241 genes were upregulated and downregulated in the H-BWG, respectively. The WGCNA analysis classified all co-expressed genes in the hypothalamus of 817 broilers into 20 modules. Among these modules, the pink module was identified as significantly negatively (r = -0.81, P = 4×10) associated with BW. Furthermore, several genes, including Wnt family member 6 (WNT6), growth differentiation factor 11 (GDF11), bone morphogenetic protein 4 (BMP4), and erb-b2 receptor tyrosine kinase 4 (ERBB4), involved in "regulation of developmental process" and "response to growth factor," were identified as hub genes that contribute to the regulation of BW. These results provide valuable information for further understanding of the gene expression and regulation affecting BW traits and will contribute to the molecular breeding of chickens in the future.