Decorin 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 ''DCN''

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 ...

. Decorin is a proteoglycan that is on average 90 - 140 kilodaltons (kDa) in molecular weight. It belongs to the small leucine-rich proteoglycan (SLRP) family and consists of a protein core containing leucine repeats with a

glycosaminoglycan Glycosaminoglycans (GAGs) or mucopolysaccharides are long, linear polysaccharides consisting of repeating disaccharide units (i.e. two-sugar units). The repeating two-sugar unit consists of a uronic sugar and an amino sugar, except in the case ...

(GAG) chain consisting of either chondroitin sulfate (CS) or dermatan sulfate (DS). Decorin is a small cellular or pericellular matrix proteoglycan and is closely related in structure to

biglycan Biglycan is a small leucine-rich repeat proteoglycan (SLRP) which is found in a variety of extracellular matrix tissues, including bone, cartilage and tendon. In humans, biglycan is encoded by the ''BGN'' gene which is located on the X chromoso ...

protein. Decorin and biglycan are thought to be the result of a gene duplication. This protein is a component of connective tissue, binds to

type I collagen Type I collagen is the most abundant collagen of the human body. It forms large, eosinophilic fibers known as collagen fibers. It is present in scar tissue, the end product when tissue heals by repair, as well as tendons, ligaments, the endomy ...

fibrils, and plays a role in matrix assembly.

Naming

Decorin's name is a derivative of both the fact that it "decorates" collagen type I, and that it interacts with the "d" and "e" bands of fibrils of this collagen.

Function

Decorin appears to influence

fibrillogenesis Fibrillogenesis is the development of fine fibrils normally present in collagen fibers of connective tissue. It is derived from the Greek ''fibrillo'' (meaning fibrils, or pertaining to fibrils) and ''genesis'' (to create, the process by which some ...

, and also interacts with fibronectin,

thrombospondin Thrombospondins (TSPs) are a family of secreted glycoproteins with antiangiogenic functions. Due to their dynamic role within the extracellular matrix they are considered matricellular proteins. The first member of the family, thrombospondin 1 (TH ...

, the complement component C1q, epidermal growth factor receptor (EGFR) and transforming growth factor-beta (

TGF-beta Transforming growth factor beta (TGF-β) is a multifunctional cytokine belonging to the transforming growth factor superfamily that includes three different mammalian isoforms (TGF-β 1 to 3, HGNC symbols TGFB1, TGFB2, TGFB3) and many other ...

). Decorin has been shown to either enhance or inhibit the activity of

TGF-beta 1 Transforming growth factor beta (TGF-β) is a multifunctional cytokine belonging to the transforming growth factor superfamily that includes three different mammalian isoforms (TGF-β 1 to 3, HGNC symbols TGFB1, TGFB2, TGFB3) and many other si ...

. The primary function of decorin involves regulation during the

cell cycle The cell cycle, or cell-division cycle, is the series of events that take place in a cell that cause it to divide into two daughter cells. These events include the duplication of its DNA (DNA replication) and some of its organelles, and sub ...

. It has been involved in the regulation of autophagy, of endothelial cell and inhibits angiogenesis. This process is mediated by a high-affinity interaction with

VEGFR2 Kinase insert domain receptor (KDR, a type IV receptor tyrosine kinase) also known as vascular endothelial growth factor receptor 2 (VEGFR-2) is a VEGF receptor. ''KDR'' is the human gene encoding it. KDR has also been designated as CD309 (cluster ...

(vascular endothelial growth factor receptor) which leads to increased levels of tumor suppressor gene called ''PEG3''. Other angiogenic growth factors that decorin inhibits are angiopoietin, hepatocyte growth factor (HGF) and platelet-derived growth factor ( PDGF). Decorin has recently been established as a

myokine A myokine is one of several hundred cytokines or other small proteins (~5–20 kDa) and proteoglycan peptides that are produced and released by skeletal muscle cells (muscle fibers) in response to muscular contractions. They have autocrine, paracr ...

. In this role, it promotes muscle

hypertrophy Hypertrophy is the increase in the volume of an organ or tissue due to the enlargement of its component cells. It is distinguished from hyperplasia, in which the cells remain approximately the same size but increase in number.Updated by Linda J. ...

by binding with

myostatin Myostatin (also known as growth differentiation factor 8, abbreviated GDF8) is a protein that in humans is encoded by the ''MSTN'' gene. Myostatin is a myokine that is produced and released by myocytes and acts on muscle cells to inhibit muscle ...

Clinical significance

Keloid scars have decreased decorin expression compared to healthy

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different de ...

. Development of congenital stromal corneal dystrophy is dependent on export and extracellular deposition of truncated decorin.

Animal studies

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. The decorin-deficient

knockout mouse A knockout mouse, or knock-out mouse, is a genetically modified mouse (''Mus musculus'') in which researchers have inactivated, or " knocked out", an existing gene by replacing it or disrupting it with an artificial piece of DNA. They are importa ...

shows reduced inflammatory reactions during

contact dermatitis Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes are ...

due to a defect in leukocyte recruitment and altered

interferon gamma Interferon gamma (IFN-γ) is a dimerized soluble cytokine that is the only member of the type II class of interferons. The existence of this interferon, which early in its history was known as immune interferon, was described by E. F. Wheeloc ...

function.

Interactions

Decorin has been shown to interact with: * Collagen type I * Epidermal growth factor receptor and *

TGF beta 1 TGF may refer to: Medicine * Tubuloglomerular feedback, a reflex of the nephrons in the kidney * Transforming growth factor, either of two classes of polypeptide growth factors (TGF-α and TGF-β) Science * Terrestrial gamma-ray flash, a burst o ...

, *

TLR2 Toll-like receptor 2 also known as TLR2 is a protein that in humans is encoded by the ''TLR2'' gene. TLR2 has also been designated as CD282 (cluster of differentiation 282). TLR2 is one of the toll-like receptors and plays a role in the immune sys ...

, and *

TLR4 Toll-like receptor 4 is a protein that in humans is encoded by the ''TLR4'' gene. TLR4 is a transmembrane protein, member of the toll-like receptor family, which belongs to the pattern recognition receptor (PRR) family. Its activation leads to an ...

References

External links

GeneReviews/NCBI/NIH/UW entry on Congenital Stromal Corneal Dystrophy
{{TGFβ receptor superfamily modulators Extracellular matrix proteins LRR domain Proteoglycans LRR proteins