Kollmar R, Nakamura S K, Kappler J A, Hudspeth A J
Laboratory of Sensory Neuroscience and Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10021-6399, USA.
Proc Natl Acad Sci U S A. 2001 Aug 28;98(18):10196-201. doi: 10.1073/pnas.171325898. Epub 2001 Aug 21.
Claudins, the major transmembrane proteins of tight junctions, are members of the tetraspanin superfamily of proteins that mediate cellular adhesion and migration. Their functional importance is demonstrated by mutations in claudin genes that eliminate tight junctions in myelin and the testis, abolish Mg(2+) resorption in the kidney, and cause autosomal recessive deafness. Here we report that two paralogs among 15 claudin genes in the zebrafish, Danio rerio, are expressed in the otic and lateral-line placodes at their earliest stages of development. Related claudins in amphibians and mammals are expressed in a similar manner in vertebrate primordia such as sensory placodes, branchial arches, and limb buds. We also show that the claudin gene family may have expanded along the chordate stem lineage from urochordates to gnathostomes, in parallel with the elaboration of vertebrate characters. We propose that tight junctions not only form barriers in mature epithelia, but also participate in vertebrate morphogenesis.
紧密连接的主要跨膜蛋白claudins是介导细胞黏附和迁移的四跨膜蛋白超家族的成员。claudin基因突变消除了髓鞘和睾丸中的紧密连接、废除了肾脏中的Mg(2+)重吸收并导致常染色体隐性耳聋，这证明了它们的功能重要性。在此，我们报告斑马鱼（Danio rerio）15个claudin基因中的两个旁系同源基因在其发育的最早阶段在耳和侧线原基中表达。两栖动物和哺乳动物中相关的claudins在脊椎动物原基（如感觉原基、鳃弓和肢芽）中以类似方式表达。我们还表明，claudin基因家族可能沿着脊索动物主干谱系从尾索动物扩展到有颌类动物，这与脊椎动物特征的细化是平行的。我们提出，紧密连接不仅在成熟上皮中形成屏障，而且还参与脊椎动物的形态发生。
