Rangarajan Janaki, Luo Ting, Sargent Thomas D
Laboratory of Molecular Genetics, NICHD, NIH, Bethesda, MD 20892, USA.
Dev Biol. 2006 Jul 1;295(1):206-18. doi: 10.1016/j.ydbio.2006.03.025. Epub 2006 May 3.
Protocadherins (Pcdhs), a major subfamily of cadherins, play an important role in specific intercellular interactions in development. These molecules are characterized by their unique extracellular domain (EC) with more than 5 cadherin-like repeats, a transmembrane domain (TM) and a variable cytoplasmic domain. PCNS (Protocadherin in Neural crest and Somites), a novel Pcdh in Xenopus, is initially expressed in the mesoderm during gastrulation, followed by expression in the cranial neural crest (CNC) and somites. PCNS has 65% amino acid identity to Xenopus paraxial protocadherin (PAPC) and 42-49% amino acid identity to Pcdh 8 in human, mouse, and zebrafish genomes. Overexpression of PCNS resulted in gastrulation failure but conferred little if any specific adhesion on ectodermal cells. Loss of function accomplished independently with two non-overlapping antisense morpholino oligonucleotides resulted in failure of CNC migration, leading to severe defects in the craniofacial skeleton. Somites and axial muscles also failed to undergo normal morphogenesis in these embryos. Thus, PCNS has essential functions in these two important developmental processes in Xenopus.
原钙黏蛋白（Pcdhs）是钙黏蛋白的一个主要亚家族，在发育过程中的特定细胞间相互作用中发挥重要作用。这些分子的特征在于其独特的细胞外结构域（EC），具有超过5个钙黏蛋白样重复序列、一个跨膜结构域（TM）和一个可变的细胞质结构域。PCNS（神经嵴和体节中的原钙黏蛋白）是非洲爪蟾中的一种新型Pcdh，最初在原肠胚形成期间在中胚层中表达，随后在颅神经嵴（CNC）和体节中表达。PCNS与非洲爪蟾近轴原钙黏蛋白（PAPC）具有65%的氨基酸同一性，与人类、小鼠和斑马鱼基因组中的Pcdh 8具有42-49%的氨基酸同一性。PCNS的过表达导致原肠胚形成失败，但对外胚层细胞几乎没有赋予任何特异性黏附。用两种不重叠的反义吗啉代寡核苷酸独立实现功能丧失，导致CNC迁移失败，导致颅面骨骼严重缺陷。在这些胚胎中，体节和轴向肌肉也未能经历正常的形态发生。因此，PCNS在非洲爪蟾的这两个重要发育过程中具有重要功能。
