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HLX
Identifiers
Aliases	HLX, HB24, HLX1, H2.0 like homeobox
External IDs	OMIM: 142995; MGI: 96109; HomoloGene: 7363; GeneCards: HLX; OMA:HLX - orthologs
Gene location (Human)
Chr.	Chromosome 1 (human)
End	220,885,059 bp
Gene location (Mouse)
Chr.	Chromosome 1 (mouse)
End	184,464,816 bp
RNA expression pattern
	Top expressed in
	stromal cell of endometrium; ; muscle layer of sigmoid colon; ; bone marrow; ; blood; ; placenta; ; Achilles tendon; ; upper lobe of left lung; ; right lung; ; bone marrow cells; ; right lobe of liver;
	Top expressed in
	granulocyte; ; gallbladder; ; stroma of bone marrow; ; sclerotome; ; spermatocyte; ; urethra; ; female urethra; ; tibiofemoral joint; ; yolk sac; ; male urethra;
	More reference expression data
	More reference expression data
Gene ontology
Molecular function	protein binding; sequence-specific DNA binding; DNA binding; DNA-binding transcription factor activity, RNA polymerase II-specific;
Cellular component	nucleus;
Biological process	negative regulation of T-helper 2 cell differentiation; regulation of transcription, DNA-templated; multicellular organism development; enteric nervous system development; positive regulation of organ growth; positive regulation of cell population proliferation; skeletal muscle tissue development; cell differentiation; liver development; positive regulation of T-helper 1 cell differentiation; transcription, DNA-templated; embryonic digestive tract morphogenesis; animal organ development; regulation of transcription by RNA polymerase II;
	Sources:Amigo / QuickGO
Orthologs
	3142
	15284
	ENSG00000136630
	ENSMUSG00000039377
	Q14774
	Q61670
	NM_021958
	NM_008250
	NP_068777
	NP_032276
	Wikidata
View/Edit Human	View/Edit Mouse

Homeobox Protein HB24 is a protein that in humans is encoded by the HLX gene.^[5]^[6]^[7]

Role in development

Hlx belongs to the class of homeobox transcription factors, initially cloned from a B-lymphocyte cell line.^[8] Targeted knockout of the gene has demonstrated its vital role in liver and gut organogenesis.^[9] 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.^[10] 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.^[9] 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.^[11]^[12] 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.^[9]

References

^ ^a ^b ^c GRCh38: Ensembl release 89: ENSG00000136630 – Ensembl, May 2017
^ ^a ^b ^c GRCm38: Ensembl release 89: ENSMUSG00000039377 – Ensembl, May 2017
^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^ Deguchi Y, Moroney JF, Wilson GL, Fox CH, Winter HS, Kehrl JH (April 1991). "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. PMID 1676597.
^ Kennedy MA, Rayner JC, Morris CM (July 1994). "Genomic structure, promoter sequence, and revised translation of human homeobox gene HLX1". Genomics. 22 (2): 348–55. doi:10.1006/geno.1994.1394. PMID 7806220.
^ "Entrez Gene: HLX1 H2.0-like homeobox 1 (Drosophila)".
^ Allen JD, Lints T, Jenkins NA, Copeland NG, Strasser A, Harvey RP, Adams JM (1991). "Novel murine homeo box gene on chromosome 1 expressed in specific hematopoietic lineages and during embryogenesis". Genes & Development. 5 (4): 509–20. doi:10.1101/gad.5.4.509. PMID 1672660.
^ ^a ^b ^c Hentsch B, Lyons I, Li R, Hartley L, Lints TJ, Adams JM, Harvey RP (1996). "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. doi:10.1101/gad.10.1.70. PMID 8557196.
^ Lints TJ, Hartley L, Parsons LM, Harvey RP (1996). "Mesoderm-specific expression of the divergent homeobox gene Hlx during murine embryogenesis". Developmental Dynamics. 205 (4): 457–70. doi:10.1002/(SICI)1097-0177(199604)205:4<457::AID-AJA9>3.0.CO;2-H. PMID 8901056. S2CID 33762532.
^ Douarin NM (1975). "An experimental analysis of liver development". Medical Biology. 53 (6): 427–55. PMID 765644.
^ Fukuda-Taira S (1981). "Hepatic induction in the avian embryo: specificity of reactive endoderm and inductive mesoderm". Journal of Embryology and Experimental Morphology. 63: 111–25. PMID 7310284.