Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei 10051, Taiwan ROC.
J Comp Neurol. 2013 Jun 15;521(9):2147-64. doi: 10.1002/cne.23278.
α-Internexin is one of the neuronal intermediate filament (IF) proteins, which also include low-, middle-, and high-molecular-weight neurofilament (NF) triplet proteins, designated NFL, NFM, and NFH, respectively. The expression of α-internexin occurs in most neurons as they begin differentiation and precedes the expression of the NF triplet proteins in mammals. However, little is known about the gene sequence and physiological function of α-internexin in avians. In this study we describe the molecular cloning of the mRNA sequence encoding the chicken α-internexin (chkINA) protein from embryonic brains. The gene structure and predicted amino acid sequence of chkINA exhibited high similarity to those of its zebrafish, mouse, rat, bovine, and human homologs. Data from transient-transfection experiments show that the filamentous pattern of chkINA was found in transfected cells and colocalized with other endogenous IFs, as demonstrated via immunocytochemistry using a chicken-specific antibody. The expression of chkINA was detected at the early stage of development and increased during the developmental process of the chicken. chkINA was expressed widely in chicken brains and colocalized with NF triplet proteins in neuronal processes, as assessed using immunohistochemistry. We also found that chkINA was expressed abundantly in the developing cerebellum and was the major IF protein in the parallel processes of granule neurons. Thus, we suggest that chkINA is a neuron-specific IF protein that may be a useful marker for studies of chicken brain development.
α-连接蛋白是神经元中间丝（IF）蛋白之一，还包括低、中、高分子量神经丝（NF）三聚体蛋白，分别命名为 NFL、NFM 和 NFH。α-连接蛋白的表达发生在大多数神经元开始分化时，先于哺乳动物中 NF 三聚体蛋白的表达。然而，关于禽类α-连接蛋白的基因序列和生理功能知之甚少。在这项研究中，我们描述了从胚胎脑中克隆编码鸡α-连接蛋白（chkINA）的 mRNA 序列。chkINA 的基因结构和预测的氨基酸序列与斑马鱼、小鼠、大鼠、牛和人同源物非常相似。瞬时转染实验的数据表明，chkINA 的丝状模式存在于转染细胞中，并与其他内源性 IF 共定位，这通过使用鸡特异性抗体进行免疫细胞化学得到证实。chkINA 的表达在发育早期被检测到，并在鸡的发育过程中增加。chkINA 在鸡脑中广泛表达，并与神经元突起中的 NF 三聚体蛋白共定位，这通过免疫组织化学评估得到证实。我们还发现，chkINA 在发育中的小脑大量表达，是颗粒神经元平行突起中的主要 IF 蛋白。因此，我们认为 chkINA 是一种神经元特异性 IF 蛋白，可能是研究鸡脑发育的有用标记物。
