Xu Xiaopeng, Chen Qi, Huang Qingpei, Cox Timothy C, Zhu Hao, Hu Jintian, Han Xi, Meng Ziqiu, Wang Bingqing, Liao Zhiying, Xu Wenxin, Xiao Baichuan, Lang Ruirui, Liu Jiqiang, Huang Jian, Tang Xiaokai, Wang Jinmo, Li Qiang, Liu Ting, Zhang Qingguo, Antonarakis Stylianos E, Zhang Jiao, Fan Xiaoying, Liu Huisheng, Zhang Yong-Biao
Guangzhou National Laboratory, Guangzhou, 510320, Guangdong, China.
School of Bioengineering Medicine, Beihang University, Beijing, 100191, China.
Nat Commun. 2025 May 17;16(1):4598. doi: 10.1038/s41467-025-59735-w.
Enhancers, through the combinatorial action of transcription factors (TFs), dictate both the spatial specificity and the levels of gene expression, and their aberrations can result in diseases. While a HMX1 downstream enhancer is associated with ear malformations, the mechanisms underlying bilateral constricted ear (BCE) remain unclear. Here, we identify a copy number variation (CNV) containing three enhancers-collectively termed the positional identity hierarchical enhancer cluster (PI-HEC)-that drives BCE by coordinately regulating HMX1 expression. Each enhancer exhibits distinct activity-location-structure features, and the dominant enhancer with high mobility group (HMG)-box combined with Coordinator and homeodomain TF motifs modulating its activity and specificity, respectively. Mouse models demonstrate that neural crest-derived fibroblasts with aberrant Hmx1 expression in the basal pinna, along with ectopic distal pinna expression, disrupt outer ear development, affecting cartilage, muscle, and epidermis. Our findings elucidate mammalian ear morphogenesis and underscore the complexity of synergistic regulation among enhancers and between enhancers and transcription factors.
增强子通过转录因子(TFs)的组合作用,决定基因表达的空间特异性和水平,其异常可导致疾病。虽然HMX1下游增强子与耳部畸形有关,但双侧狭窄耳(BCE)的潜在机制仍不清楚。在这里,我们鉴定出一个包含三个增强子的拷贝数变异(CNV)——统称为位置身份层次增强子簇(PI-HEC)——它通过协调调节HMX1表达来驱动BCE。每个增强子都表现出独特的活性-位置-结构特征,具有高迁移率族(HMG)-盒的显性增强子分别与协调因子和同源结构域TF基序结合,调节其活性和特异性。小鼠模型表明,耳廓基部中Hmx1表达异常的神经嵴来源的成纤维细胞,以及异位的耳廓远端表达,会破坏外耳发育,影响软骨、肌肉和表皮。我们的研究结果阐明了哺乳动物耳朵的形态发生,并强调了增强子之间以及增强子与转录因子之间协同调控的复杂性。