Biology:HLX (gene)
 Generic protein structure example |
Homeobox Protein HB24 is a protein that in humans is encoded by the HLX gene.[1][2][3]
Role in development
Hlx belongs to the class of homeobox transcription factors, initially cloned from a B-lymphocyte cell line.[4] Targeted knockout of the gene has demonstrated its vital role in liver and gut organogenesis.[5] Its expression is first noticed in embryonic day 9.5 (E9.5) in the splanchnic mesoderm caudal to the level of the heart and foregut pocket, and in the branchial arches. Around E10- E12.5, the expression becomes more prominent in the mesenchyme of the visceral organs of the gut such as liver, intestines and gall bladder.[6] Hlx is essential for liver and gut expansion, but not for onset of their development. Heterozygous knockouts of Hlx (Hlx +/−) are normal whereas homozygous knockouts (Hlx −/–) develop severe hypoplasia of the liver and gut along with anaemia. Hlx controls the epithelial-mesenchymal interaction necessary for liver and gut expansion.[5] At E8.0, the primary liver bud is formed from the midgut endoderm in response to signals from the cardiogenic mesoderm. This is followed by signals from the septum transversum that induce epithelial-mesenchymal transition in the hepatic progenitors of the gut endoderm.[7][8] In a third stage, these signaling factors induce the liver endoderm to undergo proliferation and form liver cords. The same factor controls gut proliferation, and Hlx governs its expression. Although these mice develop anaemia, it is likely due to insufficient support from the liver in producing matrix component needed for hematopoiesis rather than an intrinsic defect in the hematopoietic cells.[5]
References
- ↑ "Cloning of a human homeobox gene that resembles a diverged Drosophila homeobox gene and is expressed in activated lymphocytes". The New Biologist 3 (4): 353–63. April 1991. PMID 1676597.
- ↑ "Genomic structure, promoter sequence, and revised translation of human homeobox gene HLX1". Genomics 22 (2): 348–55. July 1994. doi:10.1006/geno.1994.1394. PMID 7806220.
- ↑ "Entrez Gene: HLX1 H2.0-like homeobox 1 (Drosophila)". https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=3142.
- ↑ "Novel murine homeo box gene on chromosome 1 expressed in specific hematopoietic lineages and during embryogenesis". Genes & Development 5 (4): 509–20. 1991. doi:10.1101/gad.5.4.509. PMID 1672660.
- ↑ 5.0 5.1 5.2 "Hlx homeo box gene is essential for an inductive tissue interaction that drives expansion of embryonic liver and gut". Genes & Development 10 (1): 70–9. 1996. doi:10.1101/gad.10.1.70. PMID 8557196.
- ↑ "Mesoderm-specific expression of the divergent homeobox gene Hlx during murine embryogenesis". Developmental Dynamics 205 (4): 457–70. 1996. doi:10.1002/(SICI)1097-0177(199604)205:4<457::AID-AJA9>3.0.CO;2-H. PMID 8901056.
- ↑ "An experimental analysis of liver development". Medical Biology 53 (6): 427–55. 1975. PMID 765644.
- ↑ "Hepatic induction in the avian embryo: specificity of reactive endoderm and inductive mesoderm". Journal of Embryology and Experimental Morphology 63: 111–25. 1981. PMID 7310284.
Further reading
- "Two diverged human homeobox genes involved in the differentiation of human hematopoietic progenitors map to chromosome 1, bands q41-42.1". Genes, Chromosomes & Cancer 5 (4): 343–7. November 1992. doi:10.1002/gcc.2870050410. PMID 1283323.
- "Stable expression of HB24, a diverged human homeobox gene, in T lymphocytes induces genes involved in T cell activation and growth". The Journal of Biological Chemistry 267 (12): 8222–9. April 1992. doi:10.1016/S0021-9258(18)42430-1. PMID 1349016.
- "A diverged homeobox gene is involved in the proliferation and lineage commitment of human hematopoietic progenitors and highly expressed in acute myelogenous leukemia". Blood 79 (11): 2841–8. June 1992. doi:10.1182/blood.V79.11.2841.2841. PMID 1375114.
- "Novel murine homeo box gene on chromosome 1 expressed in specific hematopoietic lineages and during embryogenesis". Genes & Development 5 (4): 509–20. April 1991. doi:10.1101/gad.5.4.509. PMID 1672660.
- "Selective expression of two homeobox genes in CD34-positive cells from human bone marrow". Blood 78 (2): 323–8. July 1991. doi:10.1182/blood.V78.2.323.323. PMID 1712647.
- "High expression of two diverged homeobox genes, HB24 and HB9, in acute leukemias: molecular markers of hematopoietic cell immaturity". Leukemia 7 (3): 446–51. March 1993. PMID 7680402.
- "A human homeobox gene, HB24, inhibits development of CD4+ T cells and impairs thymic involution in transgenic mice". The Journal of Biological Chemistry 268 (5): 3646–53. February 1993. doi:10.1016/S0021-9258(18)53742-X. PMID 8094082.
- "Linkage localization of TGFB2 and the human homeobox gene HLX1 to chromosome 1q". Genomics 15 (2): 357–64. February 1993. doi:10.1006/geno.1993.1068. PMID 8095486.
- "Isolation and identification of homeobox genes from the human placenta including a novel member of the Distal-less family, DLX4". Gene 187 (1): 55–61. March 1997. doi:10.1016/S0378-1119(96)00706-8. PMID 9073066.
- "Homeobox genes DLX4 and HB24 are expressed in regions of epithelial-mesenchymal cell interaction in the adult human endometrium". Molecular Human Reproduction 4 (5): 497–501. May 1998. doi:10.1093/molehr/4.5.497. PMID 9665637.
- "Homeobox gene HLX1 expression is decreased in idiopathic human fetal growth restriction". The American Journal of Pathology 168 (2): 511–8. February 2006. doi:10.2353/ajpath.2006.050637. PMID 16436665.
- "Hlx homeobox transcription factor negatively regulates interferon-gamma production in monokine-activated natural killer cells". Blood 109 (6): 2481–7. March 2007. doi:10.1182/blood-2006-10-050096. PMID 17110450.
External links
- HLX+protein,+human at the US National Library of Medicine Medical Subject Headings (MeSH)
This article incorporates text from the United States National Library of Medicine, which is in the public domain.
 |  |
