Chick NKx-2.3 represents a novel family member of vertebrate homologues to the Drosophila homeobox gene tinman: differential expression of cNKx-2.3 and cNKx-2.5 during heart and gut development

Mech Dev. 1996 May;56(1-2):151-63. doi: 10.1016/0925-4773(96)00521-7.


NKx homeodomain proteins are members of a growing family of vertebrate transcription factors with strong homology to the NK genes in Drosophila. Here, we describe the cloning of cNKx-2.3 and cNKx-2.5 cDNAs and their expression during chick development. Both genes are expressed in the developing heart with distinct but overlapping spatio-temporal patterns. While cNKx-2.5 is activated in early precardiac mesoderm and continues to be uniformly expressed throughout the mature heart, expression of NKx-2.3 starts later in differentiated myocardial cells with regional differences compared to NKx-2.5. Additionally, both genes are expressed in adjacent domains of the developing mid- and hindgut mesoderm as well as in branchial arches. The highly conserved structure of cNKx-2.5 and its similar expression to mouse and Xenopus NKx-2.5 genes and to the Drosophila gene tinman argue that it constitutes the chick homologue of these genes. Different temporal and spatial activity of cNKx-2.3 in heart and gut as well as in a regionally restricted expression domain in the neural tube suggest that cNKx-2.3 is a member of the NK-2 gene family which may be involved in specifying mesodermally and ectodermally derived cell types in the embryo.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Avian Proteins*
  • Base Sequence
  • Chick Embryo / metabolism*
  • Chickens / genetics*
  • Chickens / growth & development
  • Drosophila melanogaster / embryology
  • Drosophila melanogaster / genetics
  • Gene Expression Regulation, Developmental*
  • Genes, Homeobox*
  • Heart / embryology*
  • Heart / growth & development
  • Homeobox Protein Nkx-2.5
  • Homeodomain Proteins / biosynthesis*
  • Homeodomain Proteins / genetics*
  • Intestinal Mucosa / metabolism
  • Intestines / embryology*
  • Mesoderm / metabolism
  • Mice
  • Molecular Sequence Data
  • Morphogenesis / genetics
  • Myocardium / metabolism*
  • Organ Specificity
  • Sequence Alignment
  • Sequence Homology
  • Sequence Homology, Amino Acid
  • Species Specificity
  • Transcription Factors / biosynthesis
  • Transcription Factors / genetics*
  • Xenopus Proteins*
  • Xenopus laevis / genetics


  • Avian Proteins
  • Homeobox Protein Nkx-2.5
  • Homeodomain Proteins
  • NKX2-3 protein, chicken
  • NKX2-5 protein, Xenopus
  • NKX2-5 protein, human
  • Nkx2-5 protein, mouse
  • Transcription Factors
  • Xenopus Proteins

Associated data

  • GENBANK/X91838