Fibromodulin

Fibromodulin is a protein that in humans is encoded by the FMOD gene.^[5][6]

FMOD
Identifiers
Aliases	FMOD, FM, SLRR2E, fibromodulin
External IDs	OMIM: 600245; MGI: 1328364; HomoloGene: 1530; GeneCards: FMOD; OMA:FMOD - orthologs
Gene location (Human) Chr. Chromosome 1 (human)[1] Band 1q32.1 Start 203,340,628 bp[1] End 203,351,758 bp[1]
Gene location (Mouse) Chr. Chromosome 1 (mouse)[2] Band 1 E4|1 58.09 cM Start 133,964,992 bp[2] End 133,976,015 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in Achilles tendon tibia cartilage tissue right coronary artery ascending aorta Descending thoracic aorta left coronary artery popliteal artery tibial arteries synovial joint Top expressed in calvaria ciliary body body of femur ankle skin of external ear semi-lunar valve aortic valve ankle joint iris conjunctival fornix More reference expression data BioGPS More reference expression data
Gene ontology Molecular function heparin binding Roundabout binding extracellular matrix structural constituent conferring compression resistance Cellular component Golgi lumen extracellular matrix lysosomal lumen extracellular space extracellular region collagen-containing extracellular matrix Biological process transforming growth factor beta receptor complex assembly keratan sulfate biosynthetic process keratan sulfate catabolic process axonogenesis collagen fibril organization Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 2331 14264 Ensembl ENSG00000122176 ENSMUSG00000041559 UniProt Q06828 P50608 RefSeq (mRNA) NM_002023 NM_021355 RefSeq (protein) NP_002014 NP_067330 Location (UCSC) Chr 1: 203.34 – 203.35 Mb Chr 1: 133.96 – 133.98 Mb PubMed search [3] [4]
Wikidata
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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]

Function

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]

Clinical significance

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.