Foxp2 deficiency impairs reproduction by modulating the hypothalamic-pituitary-gonadal axis in zebrafish.

FOXP2 was initially characterized as a transcription factor linked to speech and language disorders. Single-cell RNA sequencing (scRNA-seq) reveals that Foxp2 is enriched in the gonadotrope cluster of the pituitary gland and colocalized with the hormones LHB and FSHB in chickens and mice, implying that FOXP2 might be associated with reproduction in vertebrates. Herein, we investigated the roles of foxp2 in reproduction in a Foxp2-deficient zebrafish model. The results indicated that the loss of Foxp2 inhibits courtship behavior in adult male zebrafish. Notably, Foxp2 deficiency disrupts gonad development, leading to retardation of follicle development and a decrease in oocytes in females at the full-growth stage, among other phenotypes. The transcriptome analysis (RNA-seq) also revealed that differentially expressed genes clustered into the estrogen signaling and ovarian steroidogenesis-related signaling pathways. In addition, we found that Foxp2 deficiency could modulate the hypothalamic-pituitary-gonadal (HPG) axis, especially the regulation of lhb and fshb expression, in zebrafish. In contrast, the injection of hCG, a specific LH agonist, partially rescues Foxp2-impaired reproduction in zebrafish, suggesting that Foxp2 plays an important role in the regulation of reproduction via the HPG axis in zebrafish. Thus, our findings reveal a new role for Foxp2 in the regulation of reproduction in vertebrates.