Luo Wei, Xu Jiguo, Li Zhenhui, Xu Haiping, Lin Shudai, Wang Jiaying, Ouyang Hongjia, Nie Qinghua, Zhang Xiquan
Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.
Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China.
Cell Physiol Biochem. 2018;46(5):1768-1778. doi: 10.1159/000489361. Epub 2018 Apr 25.
BACKGROUND/AIMS: Earlobe color is a typical external trait in chicken. There are some previous studies showing that the chicken white/red earlobe color is a polygenic and sex-linked trait in some breeds, but its molecular genetic and histological mechanisms still remain unclear.
We herein utilized histological section, genome-wide association study (GWAS) and RNA-seq, further to investigate the potential histological and molecular genetic mechanisms of white/red earlobe formation in Qiangyuan Partridge chicken (QYP).
through histological section analysis, we found the dermal papillary layer of red earlobes had many more blood vessels than that of white earlobes. And we identified a total of 44 SNPs from Chromosome 1, 2, 3, 4, 9, 10, 11, 13, 19, 20, 23 and Z, that was significantly associated with the chicken white/red earlobe color from GWAS, along with 73 significantly associated genes obtained (e.g., PIK3CB, B4GALT1 and TP63), supporting the fact that the white/red earlobe color was also polygenic and sex-linked in QYP. Importantly, PIK3CB and B4GALT1 are both involved in the biological process of angiogenesis, which may directly give rise to the chicken white earlobe formation through regulating blood vessel density in chicken earlobe. Additionally, through contrast of RNA-seq profiles between white earlobe skins and red earlobe skins, we further identified TP63 and CDH1 differentially expressed. Combined with the existing knowledge of TP63 in epithelial development and tumor angiogenesis, we propose that down-regulated TP63 in white earlobes may play roles in thickening the skin and decreasing the vessel numbers in dermal papillary layer, thereby contributing to the white earlobe formation via paling the redness of the skin in QYP, but the specific mechanism remains to be further clarified.
our findings advance the existing understanding of the white earlobe formation, as well as provide new clues to understand the molecular mechanism of chicken white/red earlobe color formation.
背景/目的：耳垂颜色是鸡的一种典型外部特征。先前有一些研究表明，鸡的白色/红色耳垂颜色在某些品种中是一种多基因且与性别相关的性状，但其分子遗传和组织学机制仍不清楚。
我们在此利用组织学切片、全基因组关联研究（GWAS）和RNA测序，进一步研究清远麻鸡（QYP）白色/红色耳垂形成的潜在组织学和分子遗传机制。
通过组织学切片分析，我们发现红色耳垂的真皮乳头层血管比白色耳垂多得多。我们从1号、2号、3号、4号、9号、10号、11号、13号、19号、20号、23号染色体和Z染色体上共鉴定出44个单核苷酸多态性（SNP），这些SNP与GWAS中鸡的白色/红色耳垂颜色显著相关，同时获得了73个显著相关基因（如PIK3CB、B4GALT1和TP63），支持了白色/红色耳垂颜色在QYP中也是多基因且与性别相关的这一事实。重要的是，PIK3CB和B4GALT1都参与血管生成的生物学过程，这可能通过调节鸡耳垂中的血管密度直接导致鸡白色耳垂的形成。此外，通过对比白色耳垂皮肤和红色耳垂皮肤的RNA测序图谱，我们进一步鉴定出TP63和CDH1差异表达。结合TP63在上皮发育和肿瘤血管生成方面的现有知识，我们提出白色耳垂中TP63的下调可能在增厚皮肤和减少真皮乳头层血管数量方面发挥作用，从而通过使QYP皮肤颜色变浅来促进白色耳垂的形成，但具体机制仍有待进一步阐明。
我们的研究结果推进了对白色耳垂形成的现有认识，并为理解鸡白色/红色耳垂颜色形成的分子机制提供了新线索。
