Decorin
Encyclopedia
Decorin is a proteoglycan
Proteoglycan
Proteoglycans are proteins that are heavily glycosylated. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan chain. The point of attachment is a Ser residue to which the glycosaminoglycan is joined through a tetrasaccharide bridge...
on average 90 - 140 kilodaltons (kD) in size.
It belongs to the small leucine-rich proteoglycan (SLRP) family and consists of a protein core containing leucine repeats
Leucine-rich repeat
A leucine-rich repeat is a protein structural motif that forms an α/β horseshoe fold. It is composed of repeating 20–30 amino acid stretches that are unusually rich in the hydrophobic amino acid leucine...
with a glycosaminoglycan
Glycosaminoglycan
Glycosaminoglycans or mucopolysaccharides are long unbranched polysaccharides consisting of a repeating disaccharide unit. The repeating unit consists of a hexose or a hexuronic acid, linked to a hexosamine .-Production:Protein cores made in the rough endoplasmic reticulum are posttranslationally...
(GAG) chain consisting of either chondroitin sulfate
Chondroitin sulfate
Chondroitin sulfate is a sulfated glycosaminoglycan composed of a chain of alternating sugars . It is usually found attached to proteins as part of a proteoglycan. A chondroitin chain can have over 100 individual sugars, each of which can be sulfated in variable positions and quantities...
(CS) or dermatan sulfate
Dermatan sulfate
Dermatan sulfate is a glycosaminoglycan found mostly in skin, but also in blood vessels, heart valves, tendons, and lungs....
(DS).
Decorin is a small cellular or pericellular matrix proteoglycan and is closely related in structure to biglycan
Biglycan
Biglycan is a small leucine-rich repeat proteoglycan which is found in a variety of extracellular matrix tissues, including bone, cartilage and tendon...
protein. Decorin and biglycan are thought to be the result of a gene duplication
Gene duplication
Gene duplication is any duplication of a region of DNA that contains a gene; it may occur as an error in homologous recombination, a retrotransposition event, or duplication of an entire chromosome.The second copy of the gene is often free from selective pressure — that is, mutations of it have no...
. This protein is a component of connective tissue
Connective tissue
"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...
, binds to type I collagen fibril
Fibril
Fibril is a fine fiber approximately 1 nm in diameter.Cytoplasmic fibrils are observed on the protoplasmic cylinders found in most spirochetal species, although no function of the cytoplasmic fibrils has been ascribed....
s, and plays a role in matrix
Extracellular matrix
In biology, the extracellular matrix is the extracellular part of animal tissue that usually provides structural support to the animal cells in addition to performing various other important functions. The extracellular matrix is the defining feature of connective tissue in animals.Extracellular...
assembly.
Naming
Decorin's name is a derivative of both the fact that it "decorates" collagenCollagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...
, and that it interacts with the "d" and "e" bands.
Function
Decorin appears to influence fibrillogenesisFibrillogenesis
Fibrillogenesis is the development of fine fibrils normally present in collagen fibers of connective tissue. It is derived from the Greek fibrillo and genesis ....
, and also interacts with fibronectin
Fibronectin
Fibronectin is a high-molecular weight glycoprotein of the extracellular matrix that binds to membrane-spanning receptor proteins called integrins. In addition to integrins, fibronectin also binds extracellular matrix components such as collagen, fibrin and heparan sulfate proteoglycans...
, thrombospondin
Thrombospondin
Thrombospondins are secreted proteins with antiangiogenic abilities. TSP was discovered by Nancy L. Baenziger.-Types:The thrombospondins are a family of multifunctional proteins...
, the complement component C1q
C1Q complex
The C1q complex is potentially multivalent for attachment to the complement fixation sites of immunoglobulin.The sites are on the CH2 domain of IgG and, it is thought, on the CH4 domain of IgM....
, epidermal growth factor receptor
Epidermal growth factor receptor
The epidermal growth factor receptor is the cell-surface receptor for members of the epidermal growth factor family of extracellular protein ligands...
(EGFR) and transforming growth factor-beta (TGF-beta).
In some publications, decorin has been shown to enhance the bioactivity of TGF-beta 1, in other publications, TGF-beta 1's bioactivity has been shown to be inhibited. Because of this, it is believed the primary function of decorin lies in certain aspects of regulation during the cell cycle
Cell cycle
The cell cycle, or cell-division cycle, is the series of events that takes place in a cell leading to its division and duplication . In cells without a nucleus , the cell cycle occurs via a process termed binary fission...
.
Infusion of decorin into experimental rodent spinal cord injuries has been shown to suppress scar formation and promote axon growth.
Decorin has been shown to have anti-tumorigenic properties in an experimental murine tumor model and is capable of suppressing the growth of various tumor cell lines. There are multiple alternatively spliced
Alternative splicing
Alternative splicing is a process by which the exons of the RNA produced by transcription of a gene are reconnected in multiple ways during RNA splicing...
transcript variants known for the decorin gene. Mutations in the decorin gene are associated with congenital stromal corneal dystrophy
Congenital stromal corneal dystrophy
Congenital stromal corneal dystrophy , also called Witschel dystrophy, is an extremely rare, autosomal dominant form of human corneal dystrophy. It is non-progressive and is linked to mutations in DCN gene encoding decorin protein. Only 4 families have been reported to have the disease by 2009...
.
Interactions
Decorin has been shown to interactProtein-protein interaction
Protein–protein interactions occur when two or more proteins bind together, often to carry out their biological function. Many of the most important molecular processes in the cell such as DNA replication are carried out by large molecular machines that are built from a large number of protein...
with Epidermal growth factor receptor
Epidermal growth factor receptor
The epidermal growth factor receptor is the cell-surface receptor for members of the epidermal growth factor family of extracellular protein ligands...
and TGF beta 1
TGF beta 1
Transforming growth factor beta 1 or TGF-β1 is a polypeptide member of the transforming growth factor beta superfamily of cytokines. It is a secreted protein that performs many cellular functions, including the control of cell growth, cell proliferation, cell differentiation and apoptosis...
.
Also PDCD4
PDCD4
Programmed cell death protein 4 is a protein that in humans is encoded by the PDCD4 gene. It is one of the targets of an oncomiR, MIRN21.-Interactions:PDCD4 has been shown to interact with RPS13 and Ribosomal protein L5.-Further reading:...
and MicroRNA-21.