| Description: |
(A) Hierarchical clustering heatmap derived from wild-type samples, indicating the co-expression between the three regional TF genes (gray arrows) and the eleven melanogenesis genes that are preferentially expressed in red cheek feathers within clusters 2 and 6. (B) Binding strength between four TFs (PITX1, PAX1, PAX6, and SOX10) and 10 melanogenesis genes. Binding strength was determined by counting TF binding to gene promoters and is illustrated using dot plots, where larger dots indicate higher binding strength. (C) Illustration outlining the predicted regulation of TF genes on the promotors of genes related to pheomelanin synthesis based on (B). (D) Schematic drawings of sex-dichromatic cheek feathers in male and female zebra finches, highlighting molecular candidates directing male-biased expression (red) in melanocytes of red cheek feathers. (E) A hypothetical regulatory hierarchy to connect cheek domain’s preferential TF profile with pigmentation pathway responsible for the enriched pheomelanin red color. The patterning of cheek domain is predicted to be related to PITX1 due to the detection of its transcripts within embryonic feather buds and adult feather sections from cheek domain. PAX1 in cheek dermal fibroblasts may serve as an upstream regulator, potentially triggering the male-biased color pattern through PAX6 and SOX10. PAX6 and SOX10 in melanocytes may enhance the expression of GPR143, SLC45A2, and TMEM163, driving increased pheomelanin production in males. |