Comparative analysis of chicken Hoxb-4 regulation in transgenic mice.
We cloned the chicken Hoxb-4 gene and performed in situ analysis to investigate conservation in patterns of expression between the chicken and mouse. The anterior boundaries of expression for both genes in segmented tissues, such as the hindbrain and paraxial mesoderm, map to the same rhombomere (r) (r6/r7) and somite (s) (s6/s7) limits, showing a direct correlation between expression of a specific Hox gene and patterning identical axial structures in both species. Given this similarity in expression we have tested the functional activity of cis-regulatory regions from the chicken Hoxb-4 gene in transgenic mice to identify and map components conserved between the species. We identified enhancers which contain conserved blocks of sequence identity and which are necessary to mediate mesodermal and neural restricted patterns of expression. However, only the neural enhancer directs the proper anterior boundary of expression (r6/r7), indicating that only a subset of the underlying molecular components regulating Hoxb-4 expression are functionally conserved between species.
Morrison
A
A
Division of Developmental Neurobiology, MRC National Institute for Medical Research, London, UK.
Chaudhuri
C
C
Ariza-McNaughton
L
L
Muchamore
I
I
Kuroiwa
A
A
Krumlauf
R
R
D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo / Q000502:physiology*; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004742:Enhancer Elements, Genetic; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D005801:Genes, Homeobox; D016678:Genome; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D013045:Species Specificity