gbx2 homeobox gene is required for the maintenance of the isthmic region in the zebrafish embryonic brain
gbx2 homeobox gene is required for the maintenance of the isthmic region in the zebrafish embryonic brain
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DOI：
10.1002/dvdy.10409
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发表时间：
2003-11-01
影响因子：
2.5
通讯作者：
Yamasu, K
中科院分区：
文献类型：
--
作者：
Kikuta, H;Kanai, M;Yamasu, K
我们分离了斑马鱼gbx 2基因的cDNA克隆，该基因与其他脊椎动物中脑-后脑边界（MHB）的建立有关。gbx 2的空间定位的表达，观察到在MHB从90%的外延通过孵化阶段。与otx 2、wnt 1和krox 20的表达比较表明，gbx 2在后脑前部表达。通过mRNA注射的gbx 2的异位表达引起了前脑和中脑的斜视或截短，并严重影响了峡部和小脑结构，而后脑的形成没有受到显着影响。在分子水平上，gbx 2抑制了otx 2在前/中脑的表达，six 3在前前脑的表达，以及MHB特异性基因如eng 2和wnt 1的表达。相反，gbx 2没有下调后脑标记基因的表达。因此，gbx 2特异性抑制整个前脑/中脑的形成。同时，otx 2的错误表达抑制了gbx 2在胚胎脑中的表达。用反义吗啉代寡核苷酸消除Gbx 2表达破坏了中脑/前后脑区域，并且这些功能丧失效应通过在原肠胚形成结束后立即激活Gbx 2蛋白来挽救。两者合计，这些结果表明，斑马鱼gbx 2基因是必不可少的MHB的维护和/或形成的峡部结构在体节发生，而不是MHB建立在原肠胚形成。我们还建议，其他因素，包括gbx 1，需要在原肠胚形成过程中的MHB的建立。(C)2003 Wiley-Liss，Inc.
We isolated cDNA clones for the zebrafish gbx2 gene, which is implicated in the establishment of the midbrain-hindbrain boundary (MHB) in other vertebrates. Spatially localized expression of gbx2 was observed at the MHB from 90% epiboly through to the hatching stage. Comparisons with the expression of otx2, wnt1, and krox20 showed that gbx2 is expressed in the anterior hindbrain. Ectopic expression of gbx2 by mRNA injection caused cyclopia or truncation of the fore- and midbrain and severely affected isthmic and cerebellar structures, while hindbrain formation was not significantly affected. At the molecular level, gbx2 suppressed the expression of otx2 in the fore/midbrain, six3 in the anterior forebrain, and MHB-specific genes such as eng2 and wnt1. In contrast, gbx2 did not down-regulate the expression of the hindbrain marker genes. Therefore, gbx2 specifically suppressed the formation of the entire fore/midbrain. Meanwhile, misexpression of otx2 suppressed the expression of gbx2 in the embryonic brain. Abrogation of gbx2 expression with an antisense morpholino oligonucleotide disrupted the midbrain/anterior hindbrain region, and these loss-of-function effects were rescued by activating the Gbx2 protein immediately after the end of gastrulation. Taken together, these results suggest that the zebrafish gbx2 gene is essential for the maintenance of MHB and/or the formation of the isthmic structure during somitogenesis, rather than for the MHB establishment during gastrulation. We also suggest that other factors, including gbx1, is required for the establishment of the MHB during gastrulation. (C) 2003 Wiley-Liss, Inc.