Abstract
In spite of recent breakthroughs in understanding limb patterning, the genetic factors determining the differences between the forelimb and the hindlimb have not been understood. The genes Pitx1 and Tbx4 encode transcription factors that are expressed throughout the developing hindlimb but not forelimb buds. Misexpression of Pitx1 in the chick wing bud induced distal expression of Tbx4, as well as HoxC10 and HoxC11, which are normally restricted to hindlimb expression domains. Wing buds in which Pitx1 was misexpressed developed into limbs with some morphological characteristics of hindlimbs: the flexure was altered to that normally observed in legs, the digits were more toe-like in their relative size and shape, and the muscle pattern was transformed to that of a leg.
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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Animals
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Avian Proteins*
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Body Patterning
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Cell Death
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Chick Embryo
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Ectoderm / metabolism
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Feathers / embryology
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Foot / embryology
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Gene Expression Regulation, Developmental*
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Genetic Vectors
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Hindlimb / embryology*
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Hindlimb / metabolism
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Hindlimb / virology
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Homeodomain Proteins / genetics
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Homeodomain Proteins / physiology*
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Limb Buds / metabolism
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Limb Buds / virology
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Mesoderm / metabolism
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Muscle, Skeletal / embryology
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Paired Box Transcription Factors
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Retroviridae / genetics
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Retroviridae / physiology
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T-Box Domain Proteins*
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Transcription Factors / genetics*
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Transcription Factors / physiology*
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Wings, Animal / embryology*
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Wings, Animal / metabolism
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Wings, Animal / virology
Substances
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Avian Proteins
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Homeodomain Proteins
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Paired Box Transcription Factors
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T-Box Domain Proteins
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T-box transcription factor 5
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TBX4 protein, Gallus gallus
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Transcription Factors
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homeobox protein PITX1