In vivo functional analysis of the Hoxa-1 3' retinoic acid response element (3'RARE).
Retinoids are essential for normal development and both deficiency and excess of retinoic acid (RA) are teratogenic. Retinoic acid response elements (RAREs) have been identified in Hox gene promoters suggesting that endogenous retinoids may be involved in the direct control of Hox gene patterning functions. In order to test this hypothesis, we have mutated the Hoxa-1 3'RARE using the Cre-loxP targeting strategy, and studied its functional role during mouse development. We find that this enhancer plays an important role in the early establishment of the Hoxa-1 anterior expression boundary in the neural plate. This early disturbance in Hoxa-1 activation results in rhombomere and cranial nerve abnormalities reminiscent of those obtained in the Hoxa-1 total knockout, although their severity and penetrance are lower, thus providing strong evidence for direct control of Hox gene function by retinoids during normal development. Interestingly, we also find that the Hoxa-1 expression response to RA treatment is not entirely controlled by the RARE, suggesting the existence of other retinoid-induced factors mediating the Hoxa-1 response to RA and/or the presence of additional RAREs. Interestingly, although the RARE is not required for the spatiotemporal control of colinear expression of the Hoxa genes, it is absolutely required for correct Hoxa-2 expression in rhombomere 5.
Dupé
V
V
Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Collège de France, Illkirch, CU de Strasbourg, France.
Davenne
M
M
Brocard
J
J
Dollé
P
P
Mark
M
M
Dierich
A
A
Chambon
P
P
Rijli
F M
FM
D000818:Animals; D017931:DNA Primers; D004742:Enhancer Elements, Genetic; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000096:biosynthesis* / Q000235:genetics*; D006720:Homozygote; D017403:In Situ Hybridization; D019868:Kanamycin Kinase; D051379:Mice; D008817:Mice, Mutant Strains; D016297:Mutagenesis, Site-Directed; D009420:Nervous System / Q000196:embryology* / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000096:biosynthesis; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011994:Recombinant Proteins / Q000096:biosynthesis; D011995:Recombination, Genetic; D017384:Sequence Deletion; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics*; D014212:Tretinoin / Q000494:pharmacology*; D000099261:Homeobox A1 Protein
D017931:DNA Primers; D018398:Homeodomain Proteins; D019868:Kanamycin Kinase; D017853:Phosphotransferases (Alcohol Group Acceptor); D011994:Recombinant Proteins; D014157:Transcription Factors; D014212:Tretinoin; D000099261:Homeobox A1 Protein