Li Hegang, Du Mengmeng, Lin Xiaokun, Cao Xinxin, Leng Lu, Campo F M Perez, Xu Dongliang, Hou Lele, Gao Xiaoxiao, Zhou Jianyu, Cheng Ming, Wang Jianguang, Zhao Qinan, Chen Yin, Yang Feng, Zhao Jinshan
Qingdao Agricultural University, Qingdao, China.
University of Cantabria, Torrelavega, Santandery, Spain.
Genet Sel Evol. 2025 Jul 1;57(1):34. doi: 10.1186/s12711-025-00981-3.
Horn development is a key ruminant trait involving multi-cell type coordination via molecular pathways. This study used scRNA-seq to analyze cellular heterogeneity and fate trajectories during early horn bud niche formation, revealing key gene expression profiles. Combining with hematoxylin-eosin (HE) staining and immunohistochemical analysis, we further verified the asynchronous developmental pathways of key cells in the skin tissue of fetal goat horn bud at induction (embryonic day (E) 50; E50), organogenesis (E60), and cytodifferentiation (E70) stages, and demonstrated the signal transmission routes for the development of early horn buds.
We revealed temporal and spatial differences of the main signal transmission of horn bud development combining with existing literatures. We speculated that multiple cell types under the guidance of nerve cells collaborated on horn bud initiation in dairy goats. In detail, neural cells receive initial horn bud signals, stimulating hair follicle cell degeneration and transmitting to dermal cells, which evolve through intermediates, amplify signals to epithelial cells, and differentiate into mesenchymal cells. Nerve cell branches also trigger neural crest cell production/migration, working with chondrocytes to promote keratinocyte differentiation for horn bud formation. In addition, we further identified the early horn bud developmental specific events, including the screening of biological functions, signaling pathways and key candidate genes.
This study employed scRNA-seq to characterize cell fate trajectories and gene expression profiles in goat fetal horn buds. Histological comparisons between hornless and horned fetuses revealed cellular heterogeneity in epithelial, dermal, nerve, and hair follicle cells, with pseudo-time analysis identifying distinct differentiation paths. Dermal and epithelial cell transcriptional dynamics were critical for horn bud initiation (branch 1), supported by immunohistochemistry. Keratinocyte and nerve cell state transitions actively regulated horn development, with asynchronous cell development visualized via immunohistochemistry. Functional enrichment analyses (GO/KEGG) highlighted neural crest development and keratinocyte differentiation pathways, identifying candidate genes (EGR1, ZEB2, SFRP2, KRT10, FMOD, CENPW, LDB1, TWIST1) involved in horn morphogenesis. These findings advance understanding of goat horn development and genetic determinants.
角的发育是反刍动物的一个关键性状，涉及通过分子途径进行的多细胞类型协调。本研究利用单细胞RNA测序（scRNA-seq）分析早期角芽微环境形成过程中的细胞异质性和命运轨迹，揭示关键基因表达谱。结合苏木精-伊红（HE）染色和免疫组织化学分析，我们进一步验证了胎山羊角芽皮肤组织在诱导期（胚胎日（E）50；E50）、器官发生期（E60）和细胞分化期（E70）关键细胞的异步发育途径，并展示了早期角芽发育的信号传递途径。
结合现有文献，我们揭示了角芽发育主要信号传递的时空差异。我们推测，在神经细胞的引导下，多种细胞类型协同作用于奶山羊角芽的起始。具体而言，神经细胞接收角芽起始信号，刺激毛囊细胞退化并传递给真皮细胞，真皮细胞通过中间细胞进化，将信号放大传递给上皮细胞，并分化为间充质细胞。神经细胞分支还触发神经嵴细胞的产生/迁移，与软骨细胞共同促进角质形成细胞分化以形成角芽。此外，我们进一步确定了早期角芽发育的特异性事件，包括生物学功能、信号通路和关键候选基因的筛选。
本研究采用scRNA-seq表征山羊胎儿角芽中的细胞命运轨迹和基因表达谱。无角和有角胎儿之间的组织学比较揭示了上皮、真皮、神经和毛囊细胞中的细胞异质性，伪时间分析确定了不同的分化路径。真皮和上皮细胞的转录动态对角芽起始（分支1）至关重要，免疫组织化学提供了支持。角质形成细胞和神经细胞状态转变积极调节角的发育，通过免疫组织化学观察到细胞发育的异步性。功能富集分析（GO/KEGG）突出了神经嵴发育和角质形成细胞分化途径，鉴定了参与角形态发生的候选基因（EGR1、ZEB2、SFRP2、KRT10、FMOD、CENPW、LDB1、TWIST1）。这些发现推进了对山羊角发育及其遗传决定因素的理解。
