Cux1 (CUTL1, CDP, CDP/Cux) is a homeodomain
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, respon ...
that in humans is encoded by the ''CUX1''
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 protein encoded by this gene is a member of the homeodomain family of DNA binding proteins. It regulates gene expression, morphogenesis, and differentiation and it also plays a role in cell cycle progression, particularly at S-phase. Several alternatively spliced transcript variants of this gene have been described, but the full-length nature of some of these variants has not been determined, and the p200 isoform of Cux1 is processed proteolytically to smaller active isoforms, such as p110.
Cux1 DNA binding is stimulated by activation of the
PAR2/F2RL1 cell-surface G-protein-coupled receptor in fibroblasts and breast-cancer epithelial cells to regulate
Matrix metalloproteinase 10,
Interleukin1-alpha, and
Cyclo-oxygenase 2 (COX2) genes.
Role in tumor growth
Genetic data from over 7,600 cancer patients shows that over 1% has the deactivated CUX1 which links to progression of tumor growth. Researchers from the
Wellcome Trust Sanger Institute
The Wellcome Sanger Institute, previously known as The Sanger Centre and Wellcome Trust Sanger Institute, is a non-profit British genomics and genetics research institute, primarily funded by the Wellcome Trust.
It is located on the Wellcome Ge ...
reported that the mutation of CUX1 reduces the inhibitory effects of a biological inhibitor,
PIK3IP1 (phosphoinositide-3-kinase interacting protein 1), resulted in higher activity of the growth promoting
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...
,
phosphoinositide 3-kinase
Phosphoinositide 3-kinases (PI3Ks), also called phosphatidylinositol 3-kinases, are a family of enzymes involved in cellular functions such as cell growth, proliferation, differentiation, motility, survival and intracellular trafficking, which i ...
(PI3K) which leads to tumor progression. Although CUX1 is mutated at a lower rate compared to other known gene mutations that cause cancer, this deactivated gene is found across many cancer types in this study to be the underlying cause of the disease.
CASP

Tne CUX1 gene Alternatively Spliced Product was first reported in 1997.
The CUX1 gene has up to 33
exon
An exon is any part of a gene that will form a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term ''exon'' refers to both the DNA sequence within a gene and to the corresponding sequenc ...
s. CASP
mRNA
In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of synthesizing a protein.
mRNA is created during the ...
includes exons 1 through 14 and 25 through 33.
The human CASP protein is predicted to contain 678
amino acids, of which 400 are shared with CUTL1.
CASP protein is approximately 80
k D.
It lacks the DNA binding region of CUTL1,
but instead contains a trans-membrane domain that allows it to insert into lipid bilayers.
It has been localized to the
Golgi apparatus
The Golgi apparatus (), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. Part of the endomembrane system in the cytoplasm, it packages proteins into membrane-bound vesicles ...
.
CASP has been reported to be part of a complex with
Golgin 84 that tethers
COPI
COPI is a coatomer, a protein complex that coats vesicles transporting proteins from the ''cis'' end of the Golgi complex back to the rough endoplasmic reticulum (ER), where they were originally synthesized, and between Golgi compartments. This ...
vesicles and is important for retrograde transport in the Golgi and between the Golgi and
endoplasmic reticulum
The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum ( ...
.
The targeting of vesicles involves tethers and
SNARE
SNARE proteins – " SNAP REceptor" – are a large protein family consisting of at least 24 members in yeasts, more than 60 members in mammalian cells,
and some numbers in plants. The primary role of SNARE proteins is to mediate vesicle ...
s.
Interactions

Cux1 (CUTL1, CDP, CDP/Cux) has been shown to
interact
Advocates for Informed Choice, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) nonprofit organization using innovative strategies to advocate for the legal and human rights of children with intersex traits. The organizat ...
with:
*
CREB binding protein,
*
Retinoblastoma protein
The retinoblastoma protein (protein name abbreviated pRb; gene name abbreviated ''Rb'', ''RB'' or ''RB1'') is a proto-oncogenic tumor suppressor protein that is dysfunctional in several major cancers. One function of pRb is to prevent excessive ...
,
and
*
SATB1
These physical interactions are reported in
BioPlex
BioPlex (biophysical interactions of ORFeome-based complexes) is an open access resource for studying protein-protein interactions. It is the result of collaborations between Harvard Medical School and Biogen. BioPlex 1.0 reported 23,744 interact ...
2.0
*
MAGEA10
*
EXT2
The ext2 or second extended file system is a file system for the Linux kernel. It was initially designed by French software developer Rémy Card as a replacement for the extended file system (ext). Having been designed according to the same p ...
*
RAB30
*
HLA-DQA1
Major histocompatibility complex, class II, DQ alpha 1, also known as HLA-DQA1, is a human gene present on short arm of chromosome 6 (6p21.3) and also denotes the genetic locus which contains this gene. The protein encoded by this gene is one of tw ...
*
STX6
*
WDR83
*
SLC39A4
*
LAMP1
Lysosomal-associated membrane protein 1 (LAMP-1) also known as lysosome-associated membrane glycoprotein 1 and CD107a (Cluster of Differentiation 107a), is a protein that in humans is encoded by the ''LAMP1'' gene. The human ''LAMP1'' gene is locat ...
*
POTEB
*
SLC39A12
Solute carrier family 39 member 12 is a protein that in humans is encoded by the SLC39A12 gene.
Function
Zinc is an essential cofactor for hundreds of enzymes. It is involved in protein, nucleic acid, carbohydrate, and lipid metabolism, as ...
Notes
References
Further reading
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External links
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{{Transcription factors, g3
Transcription factors