Hematopoietically-expressed homeobox protein HHEX is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
that in humans is encoded by the ''HHEX''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
and also known as Proline Rich Homeodomain protein PRH.
This gene encodes a member of the
homeobox
A homeobox is a Nucleic acid sequence, DNA sequence, around 180 base pairs long, that regulates large-scale anatomical features in the early stages of embryonic development. Mutations in a homeobox may change large-scale anatomical features of ...
family of
transcription factor
In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription (genetics), transcription of genetics, genetic information from DNA to messenger RNA, by binding t ...
s, many of which are involved in developmental processes. Expression in specific hematopoietic lineages suggests that this protein may play a role in
hematopoietic
Haematopoiesis (; ; also hematopoiesis in American English, sometimes h(a)emopoiesis) is the formation of blood cellular components. All cellular blood components are derived from haematopoietic stem cells. In a healthy adult human, roughly ten ...
differentiation but the expression of this protein is not limited to hematopoietic cells.
Function
The HHEX transcription factor acts as a activator of transcription in some instances and a repressor of transcription others.
It interacts with a number of other signaling molecules to play an important role in the development of multiple organs, such as the liver, thyroid and forebrain.
HHEX serves to repress VEGFA, another protein which is important in endothelial cell development.
SCL, a significant transcription factor for blood and endothelial cell differentiation, is shown to interact with HHEX to promote the correct development of the hematopoiesis process.
HHEX appears to work together with another molecule, β-catenin, for the development of the anterior organizer.
It also contributes to developmental remodeling and stabilization of endothelial cells in an unborn organism.
The importance of this transcription factor is illustrated by the inability of HHEX knockout mice embryos to survive gestation. Without the expression of HHEX, these mice embryos die in utero between Day 13 and Day 16.
HHEX knockout mice display a range of abnormalities including forebrain abnormalities in various levels of severity, as well as a number of other defects including heart, vasculature, liver, monocyte, and thyroid abnormalities.
The HHEX protein is important in a variety of cancers and it can act as a tumour suppressor protein or as an oncoprotein depending on the cancer type.
Interactions
HHEX has been shown to
interact
Advocates for Informed Choice, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) nonprofit organization advocating for the legal and human rights of children with intersex traits. The organization was founded in 2006 and fo ...
with
Promyelocytic leukemia protein
Promyelocytic leukemia protein (PML) (also known as MYL, RNF71, PP8675 or TRIM19) is the protein product of the ''PML'' gene. PML protein is a tumor suppressor protein required for the assembly of a number of nuclear structures, called PML-nucle ...
.
References
Further reading
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External links
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{{Transcription factors, g3
Transcription factors