Insertion of a targeting construct in a Hoxd-10 allele can influence the control of Hoxd-9 expression.
A neomycin resistance (neo) gene driven by the phosphoglycerokinase (PGK) promoter was inserted into the Hoxd-10 homeobox by homologous recombination in embryonic stem (ES) cells. Chimeric mice derived from ES cell-injected blastocysts died shortly after birth. Craniofacial and axial abnormalities were found in the skeleton of these chimeras, resembling some of the previously described Hox gene gain-of-function phenotypes. The spatial expression patterns of various Hoxd gene transcripts were analysed in chimeric mutant embryos by in situ hybridization. Two main observations were made: (1) a wide ectopic expression domain of the Hoxd-9 gene was found in the spinal cord of these embryos, and (2) the neo gene exhibited a specific Hox-like expression domain which extended far more rostrally than that of the Hoxd-10 gene, showing that, in the context of this mutation, the PGK promoter could be regulated as a Hox promoter. These results provide the first evidence that a targeted insertion into a Hox gene coding sequence, in the context of its own cluster, could result in misexpression of a neighbour gene of the complex.
Rijli
F M
FM
Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS, INSERM, ULP, Collège de France, Illkirch, C.U. de Strasbourg, France.
Dollé
P
P
Fraulob
V
V
LeMeur
M
M
Chambon
P
P
D000483:Alleles; D000818:Animals; D001842:Bone and Bones / Q000002:abnormalities; D002460:Cell Line; D002678:Chimera / Q000235:genetics; D004351:Drug Resistance / Q000235:genetics; D005147:Facial Bones / Q000002:abnormalities; D018507:Gene Expression Regulation, Developmental; D018390:Gene Targeting; D005801:Genes, Homeobox; D017403:In Situ Hybridization; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D005810:Multigene Family; D009355:Neomycin / Q000494:pharmacology; D011995:Recombination, Genetic; D012886:Skull / Q000002:abnormalities; D013234:Stem Cells
D009355:Neomycin