Paired related homeobox 1 is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
that in humans is encoded by the ''PRRX1''
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
.
Function
The DNA-associated protein encoded by this gene is a member of the paired family of
homeobox proteins localized to the nucleus. The protein functions as a
transcription coactivator
A coactivator is a type of transcriptional coregulator that binds to an activator (a transcription factor) to increase the rate of transcription of a gene or set of genes. The activator contains a DNA binding domain that binds either to a DNA ...
, enhancing the DNA-binding activity of
serum response factor
Serum response factor, also known as SRF, is a transcription factor protein.
Function
Serum response factor is a member of the MADS (MCM1, Agamous, Deficiens, and SRF) box superfamily of transcription factors. This protein binds to the serum ...
, a protein required for the induction of genes by growth and differentiation factors. The protein regulates muscle
creatine kinase
Creatine kinase (CK), also known as creatine phosphokinase (CPK) or phosphocreatine kinase, is an enzyme () expressed by various tissues and cell types. CK catalyses the conversion of creatine and uses adenosine triphosphate (ATP) to create pho ...
, indicating a role in the establishment of diverse
mesodermal
The mesoderm is the middle layer of the three germ layers that develops during gastrulation in the very early development of the embryo of most animals. The outer layer is the ectoderm, and the inner layer is the endoderm.Langman's Medical Embry ...
muscle types. Alternative splicing yields two isoforms that differ in abundance and expression patterns.
Role in mesenchymal stem cell differentiation
''Prrx1'' expression is restricted to the
mesoderm during
embryonic development, and both Prrx1 and
Prrx2 are expressed in
mesenchymal
Mesenchyme () is a type of loosely organized animal embryonic connective tissue of undifferentiated cells that give rise to most tissues, such as skin, blood or bone. The interactions between mesenchyme and epithelium help to form nearly every ...
tissues in adult mice.
Mice that lack both Prrx1 and Prrx2 have profound defects in mesenchymal cell differentiation in the
craniofacial Craniofacial (''cranio-'' combining form meaning head or skull + ''-facial'' combining form referring to the facial structures grossly) is an adjective referring to the parts of the head enclosing the brain and the face.
The term is typically used ...
region.
Several recent studies demonstrate that PRRX1 can regulate differentiation of mesenchymal precursors. For example, PRRX1 inhibits adipogenesis by activating
transforming growth factor-beta (TGF-beta) signaling,
and also acts downstream of
tumor necrosis factor-alpha
Tumor necrosis factor (TNF, cachexin, or cachectin; formerly known as tumor necrosis factor alpha or TNF-α) is an adipokine and a cytokine. TNF is a member of the TNF superfamily, which consists of various transmembrane proteins with a homolog ...
to inhibit
osteoblast differentiation.
References
Further reading
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External links
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{{Transcription factors, g3
Transcription factors