RRC ID 2449
Author Shimizu T, Bae YK, Hibi M.
Title Cdx-Hox code controls competence for responding to Fgfs and retinoic acid in zebrafish neural tissue.
Journal Development
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.
Volume 133(23)
Pages 4709-19
Published 2006-12-1
DOI 10.1242/dev.02660
PII dev.02660
PMID 17079270
MeSH Animals Fibroblast Growth Factors / pharmacology Gene Expression Regulation, Developmental Gene Targeting Genes, Homeobox Homeodomain Proteins / genetics Homeodomain Proteins / metabolism Rhombencephalon / drug effects Rhombencephalon / embryology* Rhombencephalon / metabolism Signal Transduction Spinal Cord / drug effects Spinal Cord / embryology Spinal Cord / metabolism Transcription Factors / deficiency Transcription Factors / genetics Transcription Factors / metabolism Tretinoin / pharmacology Zebrafish / embryology* Zebrafish / genetics Zebrafish / metabolism Zebrafish Proteins / deficiency Zebrafish Proteins / genetics Zebrafish Proteins / metabolism
IF 5.763
Times Cited 51
Zebrafish rw0