Gallina Donika, Palazzo Isabella, Steffenson Lillia, Todd Levi, Fischer Andy J
Department of Neuroscience, College of Medicine, Wexner Medical Center, The Ohio State University, Columbus, Ohio.
Dev Neurobiol. 2016 Sep;76(9):983-1002. doi: 10.1002/dneu.22370. Epub 2015 Dec 30.
Müller glia can be stimulated to de-differentiate, proliferate, and form Müller glia-derived progenitor cells (MGPCs) that are capable of producing retinal neurons. The signaling pathways that influence the de-differentiation of mature Müller glia and proliferation of MGPCs may include the Wnt-pathway. The purpose of this study was to investigate how Wnt-signaling influences the formation of MGPCs in the chick retina in vivo. In NMDA-damaged retinas where MGPCs are known to form, we find dynamic changes in retinal levels of potential readouts of Wnt-signaling, including dkk1, dkk3, axin2, c-myc, tcf-1, and cd44. We find accumulations of nuclear β-catenin in MGPCs that peaks at 3 days and rapidly declines by 5 days after NMDA-treatment. Inhibition of Wnt-signaling with XAV939 in damaged retinas suppressed the formation of MGPCs, increased expression of ascl1a and decreased hes5, but had no effect upon the differentiation of progeny produced by MGPCs. Activation of Wnt-signaling, with GSK3β-inhibitors, in the absence of retinal damage, failed to stimulate the formation of MGPCs, whereas activation of Wnt-signaling in damaged retinas stimulated the formation of MGPCs. In the absence of retinal damage, FGF2/MAPK-signaling stimulated the formation of MGPCs by activating a signaling network that includes Wnt/β-catenin. In FGF2-treated retinas, inhibition of Wnt-signaling reduced numbers of proliferating MGPCs, whereas activation of Wnt-signaling failed to influence the formation of proliferating MGPCs. Our findings indicate that Wnt-signaling is part of a network initiated by FGF2/MAPK or retinal damage, and activation of canonical Wnt-signaling is required for the formation of proliferating MGPCs. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 983-1002, 2016.
缪勒胶质细胞可被刺激去分化、增殖并形成能够产生视网膜神经元的缪勒胶质细胞源性祖细胞(MGPCs)。影响成熟缪勒胶质细胞去分化和MGPCs增殖的信号通路可能包括Wnt通路。本研究的目的是探究Wnt信号在体内如何影响鸡视网膜中MGPCs的形成。在已知会形成MGPCs的NMDA损伤视网膜中,我们发现Wnt信号潜在读数的视网膜水平存在动态变化,包括dkk1、dkk3、axin2、c-myc、tcf-1和cd44。我们发现MGPCs中核β-连环蛋白的积累在3天时达到峰值,并在NMDA处理后5天迅速下降。在受损视网膜中用XAV939抑制Wnt信号可抑制MGPCs的形成,增加ascl1a的表达并降低hes5,但对MGPCs产生的子代细胞的分化没有影响。在没有视网膜损伤的情况下,用GSK3β抑制剂激活Wnt信号未能刺激MGPCs的形成,而在受损视网膜中激活Wnt信号则刺激了MGPCs的形成。在没有视网膜损伤的情况下,FGF2/MAPK信号通过激活包括Wnt/β-连环蛋白的信号网络来刺激MGPCs的形成。在FGF2处理的视网膜中,抑制Wnt信号会减少增殖的MGPCs数量,而激活Wnt信号未能影响增殖的MGPCs的形成。我们的研究结果表明,Wnt信号是由FGF2/MAPK或视网膜损伤启动的网络的一部分,并且增殖性MGPCs的形成需要经典Wnt信号的激活。© 2015威利期刊公司。《发育神经生物学》76: 983 - 1002, 2016。