Retina regeneration in the chick embryo is not induced by spontaneous Mitf downregulation but requires FGF/FGFR/MEK/Erk dependent upregulation of Pax6
Retina regeneration in the chick embryo is not induced by spontaneous Mitf downregulation but requires FGF/FGFR/MEK/Erk dependent upregulation of Pax6
复制标题
鸡胚中的视网膜再生不是由自发的 Mitf 下调诱导的，而是需要 FGF/FGFR/MEK/Erk 依赖的 Pax6 上调
作者：
J. Spence;Mayur C. Madhavan;Juan;K. Del Rio
目的阐明鸡胚视网膜再生诱导过程中的早期细胞事件，着重探讨成纤维细胞生长因子（FGF）信号通路与Pax 6和Mitf调控的关系。方法取胚胎4天（E4）雏鸡的视网膜，将肝素包被的成纤维细胞生长因子2（FGF 2）浸泡珠置于视杯中。药理学抑制剂PD 173074用于抑制FGF受体，PD 98059用于抑制MAP激酶-激酶/细胞外信号调节激酶（MEK/Erk）信号传导。配对盒6（Pax 6）、MEK和小眼症（Mitf）的逆转录病毒构建体也用于过表达研究。采用免疫组织化学方法检测视网膜脱离后不同时间点pErk、Pax 6、Mitf和黑素体基质蛋白115（MMP 115）的免疫反应性及BrdU掺入。结果鸡胚具有通过视网膜色素上皮细胞转分化形成新视网膜的能力。我们观察到，在诱导转分化过程中，Mitf的下调不足以在E4诱导转分化，并且需要FGF 2来驱动Pax 6蛋白表达和细胞增殖，这两者都是转分化所必需的。此外，我们表明FGF 2通过FGFR/MEK/Erk信号级联反应来增加Pax 6表达和增殖。异位Mitf表达能够通过作用于FGFR/MEK/Erk信号传导的下游来抑制转分化，可能是通过抑制RPE中Pax 6蛋白的增加。结论FGF 2通过FGFR/MEK/Erk信号级联反应在诱导RPE转分化过程中刺激Pax 6表达。这种Pax 6表达伴随着BrdU掺入的增加。此外，我们发现，Mitf自发下调后，即使在没有FGF 2的视网膜。这种Mitf下调不伴随Pax 6上调，表明FGF 2刺激的Pax 6上调是RPE转分化所需的。此外，我们发现异位Mitf表达能够通过抑制Pax 6上调来保护RPE免受FGF 2诱导的转分化。
Purpose To elucidate the early cellular events that take place during induction of retina regeneration in the embryonic chick, focusing on the relationship between fibroblast growth factor (FGF) signaling and the regulation of Pax6 and Mitf. Methods The retina of embryonic day 4 (E4) chicks was removed and a heparin coated bead soaked in fibroblast growth factor 2 (FGF2) was placed into the optic cup. The pharmacological inhibitor PD173074 was used to inhibit FGF receptors, PD98059 was used to inhibit MAP kinase-kinase/extracellular signal-regulated kinase (MEK/Erk) signaling. Retroviral constructs for paired box 6 (Pax6), MEK, and microphthalmia (Mitf) were also used in overexpression studies. Immunohistochemistry was used to examine pErk, Pax6, Mitf, and melanosomal matrix protein 115 (MMP115) immunoreactivity and bromodeoxyuridine (BrdU) incorporation at different time points after removing the retina. Results The embryonic chick has the ability to regenerate a new retina by the process of transdifferentiation of the retinal pigment epithelium (RPE). We observed that during the induction of transdifferentiation, downregulation of Mitf was not sufficient to induce transdifferentiation at E4 and that FGF2 was required to drive Pax6 protein expression and cell proliferation, both of which are necessary for transdifferentiation. Furthermore, we show that FGF2 works through the FGFR/MEK/Erk signaling cascade to increase Pax6 expression and proliferation. Ectopic Mitf expression was able to inhibit transdifferentiation by acting downstream of FGFR/MEK/Erk signaling, likely by inhibiting the increase in Pax6 protein in the RPE. Conclusions FGF2 stimulates Pax6 expression during induction of transdifferentiation of the RPE through FGFR/MEK/Erk signaling cascade. This Pax6 expression is accompanied by an increase in BrdU incorporation. In addition, we show that Mitf is spontaneously downregulated after removal of the retina even in the absence of FGF2. This Mitf downregulation is not accompanied by Pax6 upregulation, demonstrating that FGF2 stimulated Pax6 upregulation is required for transdifferentiation of the RPE. Furthermore, we show that ectopic Mitf expression is able to protect the RPE from FGF2 induced transdifferentiation by inhibiting Pax6 upregulation.
影响因子：
4.6
作者：
Minh-Thanh T. Nguyen;H. Arnheiter
通讯作者：
Minh-Thanh T. Nguyen;H. Arnheiter
味蕾从内胚层自主发育，无需头神经嵴或轴旁中胚层的诱导。
DOI：
10.1242/dev.124.5.949
发表时间：
1997
期刊：
Development (Cambridge, England)
影响因子：
--
作者：
Barlow,LA;Northcutt,RG
通讯作者：
Northcutt,RG