Cdx-Hox code controls competence for responding to Fgfs and retinoic acid in zebrafish neural tissue
Open Access
- 1 December 2006
- journal article
- Published by The Company of Biologists in Development
- Vol. 133 (23) , 4709-4719
- https://doi.org/10.1242/dev.02660
Abstract
Fibroblast growth factor (Fgf) and retinoic acid (RA) signals control the formation and anteroposterior patterning of posterior hindbrain. They are also involved in development processes in other regions of the embryo. Therefore, responsiveness to Fgf and RA signals must be controlled in a context-dependent manner. Inhibiting the caudal-related genes cdx1a and cdx4 in zebrafish embryos caused ectopic expression of genes that are normally expressed in the posterior hindbrain and anterior spinal cord, and ectopic formation of the hindbrain motor and commissure neurons in the posteriormost neural tissue. Combinational marker analyses suggest mirror-image duplication in the Cdx1a/4-defective embryos, and cell transplantation analysis further revealed that Cdx1a and Cdx4 repress a posterior hindbrain-specific gene expression cell-autonomously in the posterior neural tissue. Expression of fgfs and retinaldehyde dehydrogenase 2 suggested that in the Cdx1a/4-defective embryos, the Fgf and RA signaling activities overlap in the posterior body and display opposing gradients, compared with those in the hindbrain region. We found that Fgf and RA signals were required for ectopic expression. Expression of the posterior hox genes hoxb7a, hoxa9a or hoxb9a, which function downstream of Cdx1a/4, or activator fusion genes of hoxa9a or hoxb9a (VP16-hoxa9a, VP16-hoxb9a) suppressed this loss-of-function phenotype. These data suggest that Cdx suppresses the posterior hindbrain fate through regulation of the posterior hox genes; the posterior Hox proteins function as transcriptional activators and indirectly repress the ectopic expression of the posterior hindbrain genes in the posterior neural tissue. Our results indicate that the Cdx-Hox code modifies tissue competence to respond to Fgfs and RA in neural tissue.Keywords
This publication has 60 references indexed in Scilit:
- TheCdx4mutation affects axial development and reveals an essential role of Cdx genes in the ontogenesis of the placental labyrinth in miceDevelopment, 2006
- Evolutionarily conserved domains required for activation and repression functions of the Drosophila Hox protein UltrabithoraxDevelopment, 2005
- Developmental regulation of the Hox genes during axial morphogenesis in the mouseDevelopment, 2005
- Interaction of Wnt and caudal-related genes in zebrafish posterior body formationDevelopmental Biology, 2005
- Retinoic acid-metabolizing enzyme Cyp26a1 is essential for determining territories of hindbrain and spinal cord in zebrafishDevelopmental Biology, 2005
- caudal is required for gnathal and thoracic patterning and for posterior elongation in the intermediate-germband cricket Gryllus bimaculatusMechanisms of Development, 2005
- Early requirement for fgf8 function during hindbrain pattern formation in zebrafishDevelopmental Dynamics, 2004
- HoxA10 Represses Gene Transcription in Undifferentiated Myeloid Cells by Interaction with Histone Deacetylase 2Published by Elsevier ,2003
- Marrying Planning, Economics and Environment: Is South Africa ahead of the curve?Development, 2000
- Organization of hindbrain segments in the zebrafish embryoNeuron, 1990