Differential Distribution of the Ca (2+) Regulator Pcp4 in the Branchial Arches Is Regulated by Hoxa2

Branchial arches are externally visible tissue bands in the head region of all vertebrate embryos. Although initially formed from similar components, each arch will give rise to different head and neck structures. In a screen designed to characterize the molecular control of branchial arch identity in mouse, we identified Pcp4 as a second branchial arch-specific molecular signature. We further show that the transcription factor Hoxa2 binds to Pcp4 chromatin and regulates Pcp4 expression in the second arch. Hoxa2 is also sufficient to induce Pcp4 expression in anterior first arch cells, which are Pcp4-negative.

鳃弓（branchial arches）是所有脊椎动物胚胎头部区域的外部可见组织带。尽管最初由相似的组分构成，每个鳃弓最终都会分化形成不同的头部与颈部结构。在一项旨在解析小鼠鳃弓身份分子调控机制的遗传学筛选实验中，我们鉴定出Pcp4作为第二鳃弓特异性的分子标记物。我们进一步证实，转录因子Hoxa2可结合Pcp4的染色质区域，并在第二鳃弓中调控Pcp4的表达。此外，Hoxa2足以在原本不表达Pcp4的第一鳃弓前部细胞中诱导Pcp4的表达。