Liu Q, Frey R A, Babb-Clendenon S G, Liu B, Francl J, Wilson A L, Marrs J A, Stenkamp D L
Department of Biology, University of Akron, 302 Buchtel Common, Akron, OH 44325, USA.
Exp Eye Res. 2007 Jan;84(1):163-75. doi: 10.1016/j.exer.2006.09.011. Epub 2006 Oct 30.
Cadherins are Ca2+ -dependent transmembrane molecules that mediate cell-cell adhesion through homophilic interactions. Cadherin2 (also called N-cadherin) and cadherin4 (also called R-cadherin), members of the classic cadherin subfamily, have been shown to be involved in development of a variety of tissues and organs including the visual system. To gain insight into cadherin2 and cadherin4 function in differentiation of zebrafish photoreceptors, we have analyzed expression patterns of several photoreceptor-specific genes (crx, gnat1, gnat2, irbp, otx5, rod opsin, rx1, and uv opsin) and/or a cone photoreceptor marker (zpr-1) in the retina of a zebrafish cadherin2 mutant, glass onion (glo) and in zebrafish embryos injected with a cadherin4 specific antisense morpholino oligonucleotide (cdh4MO). We find that expression of all these genes, and of zpr-1, is greatly reduced in the retina of both the glo and cadherin4 morphants. Moreover, in these embryos, expression of some genes (e.g. gnat1, gnat2 and irbp) is more affected than others (e.g. rod opsin and uv opsin). In embryos with both cadherins functions blocked (glo embryos injected with the cdh4MO), the eye initially formed, but became severely and progressively disintegrated and expressed little or no crx and otx5 as development proceeded. Our results suggest that cadherin2 and cadherin4 play important roles in the differentiation of zebrafish retinal photoreceptors.
钙黏着蛋白是依赖Ca2+的跨膜分子，通过同源性相互作用介导细胞间黏附。经典钙黏着蛋白亚家族成员钙黏着蛋白2（也称为N-钙黏着蛋白）和钙黏着蛋白4（也称为R-钙黏着蛋白）已被证明参与包括视觉系统在内的多种组织和器官的发育。为了深入了解钙黏着蛋白2和钙黏着蛋白4在斑马鱼光感受器分化中的功能，我们分析了斑马鱼钙黏着蛋白2突变体glass onion（glo）的视网膜以及注射了钙黏着蛋白4特异性反义吗啉代寡核苷酸（cdh4MO）的斑马鱼胚胎中几种光感受器特异性基因（crx、gnat1、gnat2、irbp、otx5、视杆视蛋白、rx1和紫外视蛋白）和/或视锥光感受器标记物（zpr-1）的表达模式。我们发现，在glo和钙黏着蛋白4 morphants的视网膜中，所有这些基因以及zpr-1的表达都大大降低。此外，在这些胚胎中，一些基因（如gnat1、gnat2和irbp）的表达比其他基因（如视杆视蛋白和紫外视蛋白）受到的影响更大。在两种钙黏着蛋白功能均被阻断的胚胎（注射了cdh4MO的glo胚胎）中，眼睛最初形成，但随着发育的进行，眼睛严重且逐渐解体，并且几乎不表达或不表达crx和otx5。我们的结果表明，钙黏着蛋白2和钙黏着蛋白4在斑马鱼视网膜光感受器的分化中起重要作用。
