Costa Mara Silvia A, Machado Maiaro Cabral R, Vieceli Felipe M, Amistá Luana, Baroneza Jose Eduardo, Yan C Y Irene, Ramos Ricardo Guelerman P
Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo , Ribeirão Preto , Brazil.
J Neurogenet. 2014 Sep-Dec;28(3-4):270-81. doi: 10.3109/01677063.2014.933220. Epub 2014 Jul 8.
The Rst-Neph family comprises an evolutionarily conserved group of single-pass transmembrane glycoproteins that belong to the immunoglobulin superfamily and participate in a wide range of cell adhesion and recognition events in both vertebrates and invertebrates. In mammals and fish, three Rst-Neph members, named Neph1-3, are present. Besides being widely expressed in the embryo, particularly in the developing nervous system, they also contribute to the formation and integrity of the urine filtration apparatus in the slit diaphragm of kidney glomerular podocytes, where they form homodimers, as well as heterodimers with Nephrin, another immunoglobulin-like cell adhesion molecule. In mice, absence of Neph1 causes severe proteinuria, podocyte effacement and perinatal death, while in humans, a mutated form of Nephrin leads to congenital nephrotic syndrome of the Finnish type. Intriguingly, neither Nephrin nor Neph3 are present in birds, which nevertheless have typical vertebrate kidneys with mammalian-like slit diaphragms. These characteristics make, in principle, avian systems very helpful for understanding the evolution and functional significance of the complex interactions displayed by Rst-Neph proteins. To this end we have started a systematic study of chicken Neph embryonic and post-embryonic expression, both at mRNA and protein level. RT-qPCR mRNA quantification of the two Neph paralogues in adult tissues showed that both are expressed in heart, brain, and retina. Neph1 is additionally present in kidney, liver, pancreas, lungs, and testicles, while Neph2 mRNA is barely detected in kidney, testicles, pancreas and absent in liver and lungs. In embryos, mRNA from both genes can already be detected at as early as stage HH14, and remain expressed until at least HH28. Finally, we used a specific antibody to examine the spatial dynamics and subcellular distribution of ggNeph2 between stages HH20-28, particularly in the mesonephros, dermomyotomes, developing heart, and retina.
Rst-Neph家族由一组进化上保守的单次跨膜糖蛋白组成，这些糖蛋白属于免疫球蛋白超家族，在脊椎动物和无脊椎动物中参与广泛的细胞黏附和识别事件。在哺乳动物和鱼类中，存在三种名为Neph1-3的Rst-Neph成员。它们除了在胚胎中广泛表达，特别是在发育中的神经系统中，还对肾小球足细胞裂孔隔膜中尿液过滤装置的形成和完整性有贡献，在那里它们形成同二聚体，以及与另一种免疫球蛋白样细胞黏附分子Nephrin形成异二聚体。在小鼠中，Neph1的缺失会导致严重蛋白尿、足细胞消失和围产期死亡，而在人类中，Nephrin的一种突变形式会导致芬兰型先天性肾病综合征。有趣的是，鸟类中既没有Nephrin也没有Neph3，但它们却有典型的脊椎动物肾脏以及类似哺乳动物的裂孔隔膜。原则上，这些特征使得鸟类系统对于理解Rst-Neph蛋白所展示的复杂相互作用的进化和功能意义非常有帮助。为此，我们开始了对鸡Neph胚胎期和胚后期表达的系统研究，包括mRNA和蛋白质水平。对成年组织中两种Neph旁系同源物的RT-qPCR mRNA定量分析表明，它们在心脏、大脑和视网膜中均有表达。Neph1还存在于肾脏、肝脏、胰腺、肺和睾丸中，而Neph2 mRNA在肾脏、睾丸、胰腺中几乎检测不到，在肝脏和肺中不存在。在胚胎中，早在HH14阶段就能检测到这两个基因的mRNA，并且至少在HH28阶段仍有表达。最后，我们使用一种特异性抗体来检测HH20-28阶段之间ggNeph2的空间动态和亚细胞分布，特别是在中肾、皮肌节、发育中的心脏和视网膜中。
