Homeobox protein CDX-4 is a protein that in humans is encoded by the CDX4 gene. This gene is a member of the caudal-related homeobox transcription factor family that also includes CDX1 and CDX2. [5]
Homeobox protein CDX-4 is a protein that in humans is encoded by the CDX4 gene. This gene is a member of the caudal-related homeobox transcription factor family that also includes CDX1 and CDX2. [5]
The transcription factor encoded by the CDX4 gene participates in the formation of extra-embryonic tissues, anterior-posterior patterning and blood formation during embryogenesis. It does so through the regulation of Hox gene expression. [6] [7] [8]
Before placentation takes place, CDX4 plays a role in its development. CDX4 mutants are born healthy and are fertile, however its importance is revealed in compound CDX mutants. Compound mutants carrying one CDX2 null allele and homozygous null for CDX4 fail to generate posterior tissue caudal to the hindlimbs and most of these embryos die around embryonic day 10.5 from lack of placental development. Around 10% of this phenotype may progress to full term, but then die shortly after birth. Upon inspection the morphogenesis of ano-rectal and urethral tissues was observed. [9] [10]
The most well described function of CDX genes are their role in caudal body formation. Transcription factors of the CDX gene family, in part control Hox gene expression by responding to signaling molecules Retinoic Acid, Wnt, and FGF. The redundant contribution of CDX4 in axial elongation is shown in that neither CDX4 null or CDX1/CDX4 compound mutants appear with impaired axial elongation. However, CDX4 does have a role in determining pancreatic B-cell number, specifying anterior-posterior location of the foregut organs including the pancreas and liver. Thus, an abnormal state is shown in embryos deficient in CDX4 by posteriorly shifted pancreas, liver and small intestines. [11] [12]
In blood formation, CDX4 regulation of Hox genes is necessary for the specification of hematopoietic cell fate during embryogenesis. This is demonstrated by the fact that blood deficiencies in CDX4 mutants can be rescued by the over expression of certain Hox genes. [13]
Knockout models have been generated in mice as described in CDX4’s role in caudal body formation.
The ParaHox gene cluster is an array of homeobox genes from the Gsx, Xlox (Pdx) and Cdx gene families.
Homeobox protein CDX-2 is a protein that in humans is encoded by the CDX2 gene. The CDX2 protein is a homeobox transcription factor expressed in the nuclei of intestinal epithelial cells, playing an essential role in the development and function of the digestive system. CDX2 is part of the ParaHox gene cluster, a group of three highly conserved developmental genes present in most vertebrate species. Together with CDX1 and CDX4, CDX2 is one of three caudal-related genes in the human genome.
Pre-B-cell leukemia transcription factor 1 is a protein that in humans is encoded by the PBX1 gene. The homologous protein in Drosophila is known as extradenticle, and causes changes in embryonic development.
Homeobox protein Hox-B7 is a protein that in humans is encoded by the HOXB7 gene.
Paired-like homeodomain transcription factor 2 also known as pituitary homeobox 2 is a protein that in humans is encoded by the PITX2 gene.
Homeobox protein Hox-A1 is a protein that in humans is encoded by the HOXA1 gene.
Homeobox protein Hox-D13 is a protein that in humans is encoded by the HOXD13 gene. This gene belongs to the homeobox family of genes. The homeobox genes encode a highly conserved family of transcription factors that play an important role in morphogenesis in all multicellular organisms.
Homeobox protein Hox-A13 is a protein that in humans is encoded by the HOXA13 gene.
Homeobox protein Hox-B1 is a protein that in humans is encoded by the HOXB1 gene.
Homeobox protein Hox-D9 is a protein that in humans is encoded by the HOXD9 gene.
Homeobox protein Hox-A3 is a protein that in humans is encoded by the HOXA3 gene.
Homeobox protein Hox-D11 is a protein that in humans is encoded by the HOXD11 gene.
Homeobox protein CDX-1 is a protein in humans that is encoded by the CDX1 gene. CDX1 is expressed in the developing endoderm and its expression persists in the intestine throughout adulthood. CDX1 protein expression varies along the intestine, with high expression in intestinal crypts and diminishing expression along intestinal villi.
Homeobox protein Hox-D12 is a protein that in humans is encoded by the HOXD12 gene.
Homeobox protein Nkx-2.3 is a protein that in humans is encoded by the NKX2-3 gene.
Homeobox protein GBX-2 is a protein that in humans is encoded by the GBX2 gene.
NK3 homeobox 2 also known as NKX3-2 is a human gene. It is a homolog of bagpipe (bap) in Drosophila and therefore also known as Bapx1. The protein encoded by this gene is a homeodomain containing transcription factor.
Homeotic genes are genes which regulate the development of anatomical structures in various organisms such as echinoderms, insects, mammals, and plants. Homeotic genes often encode transcription factor proteins, and these proteins affect development by regulating downstream gene networks involved in body patterning.
The Cdx protein family is a group of the transcription factor proteins which bind to DNA to regulate the expression of genes. In particular this family of proteins can regulate the Hox genes. They are regulators of embryonic development and hematopoiesis in vertebrates, and are also involved in the development of some types of gastrointestinal cancers and leukemias.
The Cdx gene family, also called caudal genes, are a group of genes found in many animal genomes. Cdx genes contain a homeobox DNA sequence and code for proteins that act as transcription factors. The gene after which the gene family is named is the caudal or cad gene of the fruitfly Drosophila melanogaster. The human genome has three Cdx genes, called CDX1, CDX2 and CDX4. The zebrafish has no cdx2 gene, but two copies of cdx1 and one copy of cdx4. The Cdx gene in the nematode Caenorhabditis elegans is called pal-1.
This article incorporates text from the United States National Library of Medicine, which is in the public domain.