Signal transducers and activators o

Signal transducers and activators of transcriptions (STAT), consisting of 7 members, are a family of cytoplasmic proteins that are involved in the signal transduction pathways of numerous cytokines, growth factors, and hormones (Darnell, 1997; Levy and Darnell, 2002). They participate in a series of cellular processes such as cell growth, differentiation, survival, and apoptosis. The STAT5 proteins, including STAT5A and STAT5B, which are 96% similar at the amino acid level, are the important modulators of the growth hormone, growth hormone receptor, IGF, prolactin, and insulin signaling pathways, which are involved in growth, reproduction, lactation, and metabolism (Bachelot and Binart, 2007; Pilecka et al., 2007; Hennighausen and Robinson, 2008).


The chicken IGFBP1 and IGFBP3 genes were localized to the growth QTL regions on chromosome 2, which may affect white meat percentage and other growth traits (Tatsuda and Fujinaka, 2001; McElroy et al., 2006; Park et al., 2006), and furthermore, chicken IGFBP1, IGFBP3, and STAT5B genes are 3 essential nodes for the signaling pathways and gene networks of growth and reproduction (Kanehisa and Goto, 2000; Cogburn et al., 2003; Kuhn et al., 2008). Hence, the IGFBP1, IGFBP3, and STAT5B genes may be investigated as potential candidate genes for QTL. However, few studies on association with growth and reproduction have been reported in chickens. In this paper, our objectives were to explore the association of the 3 genes of the neuroendocrine growth axis on growth or reproductive traits, or both, in chickens.