A Novel SNP in the Promoter Region of Associated With Yunshang Black Goat Kidding Number Promoting Transcription Activity by SP1.

, a member of the insulin-like growth factor (IGF) superfamily, is also known as the growth-promoting factor (somatomedin C). is involved in vertebrate growth and development, immunity, cell metabolism, reproduction, and breeding. However, there are relatively few studies on the relationship between and goat reproduction. In this study, a new transcription factor bound to the g. 64943050T>C promoted granulosa cell (GC) proliferation. A mutation g.64943050T>C located in the promoter region of was identified. Association analysis revealed that the kidding number in the first and second litters and the average number of first three litters of the CC genotype (2.206 ± 0.044, 2.254 ± 0.056, and 2.251 ± 0.031) were significantly higher than those in the TC genotype (1.832 ± 0.049, 1.982 ± 0.06, and 1.921 ± 0.034) and TT genotype (1.860 ± 0.090, 1.968 ± 0.117, and 1.924 ± 0.062) ( < 0.05). The kidding number in the third litter of the CC genotype (2.355 ± 0.057) was significantly higher than that in the TT genotype (2.000 ± 0.107) ( < 0.05). Then, the function of this mutation was validated by the dual-luciferase reporter assay and EMSA. The results showed that the luciferase activity of IGF1-mutant-C was significantly higher than that of IGF1-Wild-T ( < 0.05). The EMSA also showed that the binding ability of IGF1-mutant-C was higher than that of IGF1-Wild-T ( < 0.05). Subsequently, the transcription factor was predicted to bind to the mutation of (g.64943050T>C). Overexpression of SP1 promotes the expression of in the primary granulosa cells (GCs). The results of the CCK-8 assay and the expression of GC proliferation factors (, , and ) demonstrated that promoted GC proliferation by regulating expression. Our results suggested that the g.64943050T>C was significantly associated with the kidding number of Yunshang black goats, and as a transcription factor of binding to the mutation T>C regulated the expression of . Furthermore, promoted goat GC proliferation by regulating the expression of , which provides a new insight for the goat fertility trait.