Fibromodulin is a protein that in humans is encoded by the FMOD gene.[5][6]
FMOD | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Aliases | FMOD, FM, SLRR2E, fibromodulin | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 600245 MGI: 1328364 HomoloGene: 1530 GeneCards: FMOD | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Fibromodulin is a 42kDa protein of a family of small interstitial leucine-rich repeat proteoglycans (SLRPs). It can have up to four N-linked keratan sulfate chains attached to the core protein within the leucine-rich region. It shares significant sequence homology with biglycan and decorin.[7]
Fibromodulin participates in the assembly of the collagen fibers of the extracellular matrix. It binds to the same site on the collagen type I molecule as lumican.[8] It also inhibits fibrillogenesis of collagen type I and collagen type III in vitro.[9][10] It regulates TGF-beta activities by sequestering TGF-beta into the extracellular matrix.[6]
There is an age-dependent decline in the synthesis of keratan sulfate chains, so non-glycated forms of fibromodulin can accumulate in tissues such as cartilage.[11]
Fibromodulin is found in the epidermis of human skin and is expressed by skin cells (keratinocytes) in culture. Mice with the gene for fibromodulin knocked out (Fmod-/-) have very fragile skin[12] and abnormal tail and Achilles tendons.[13] The collagen fiber bundles in these tendons are fewer and disorganised and there is less endotenon surrounding the tendon tissue. The levels of lumican, a SLRP with one of the same collagen binding sites as fibromodulin, is increased 4 fold in the tail tendons of Fmod-knockout mice.