Abstract
The zinc finger gene Krox-20 is transcribed in two alternate segments (rhombomeres) of the developing hindbrain. To investigate its function, we have used homologous recombination to generate mice carrying an in-frame insertion of the E. coli lacZ gene within Krox-20. Analysis of the beta-galactosidase pattern in heterozygous embryos confirmed the known profile with expression restricted to rhombomeres (r) 3 and 5. Mice homozygous for the mutation die during the first two weeks after birth. Anatomical analysis of the hindbrain and of the cranial nerves during embryogenesis, combined with the determination of the expression patterns of rhombomere-specific genes, demonstrated that Krox-20 inactivation results in a marked reduction or elimination of r3 and r5. We conclude that Krox-20, although not required for the initial delimitation of r3 and r5, plays an important role in the process of segmentation governing hindbrain development.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Aging
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Animals
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Brain Stem / embryology
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Brain Stem / growth & development
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Cranial Nerves / embryology
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DNA-Binding Proteins / biosynthesis
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DNA-Binding Proteins / genetics*
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Early Growth Response Protein 2
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Embryo, Mammalian / physiology
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Escherichia coli / genetics
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Ganglia / embryology
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Gene Deletion
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Gene Expression
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Gene Expression Regulation
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Genes, Homeobox*
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Heterozygote
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Homozygote
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Mice
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Mice, Transgenic
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Mutagenesis, Insertional
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Receptors, Retinoic Acid / genetics
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Recombination, Genetic
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Rhombencephalon / embryology*
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Rhombencephalon / growth & development
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Rhombencephalon / physiology
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Transcription Factors / biosynthesis
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Transcription Factors / genetics*
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Zinc Fingers / genetics*
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beta-Galactosidase / biosynthesis
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beta-Galactosidase / genetics
Substances
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DNA-Binding Proteins
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Early Growth Response Protein 2
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Egr2 protein, mouse
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Receptors, Retinoic Acid
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Transcription Factors
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beta-Galactosidase