Lumican

Source: Wikipedia, the free encyclopedia.
LUM
Identifiers
Gene ontology
Molecular function
Cellular component
Biological process
Sources:Amigo / QuickGO
Ensembl
UniProt
RefSeq (mRNA)

NM_002345

NM_008524

RefSeq (protein)

NP_002336

NP_032550

Location (UCSC)Chr 12: 91.1 – 91.11 MbChr 10: 97.4 – 97.41 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

Lumican,[5] also known as LUM, is an extracellular matrix protein that, in humans, is encoded by the LUM gene on chromosome 12.[6][7]

Structure

Lumican is a proteoglycan Class II member of the small leucine-rich proteoglycan (SLRP) family that includes decorin, biglycan, fibromodulin, keratocan, epiphycan, and osteoglycin.[8]

Like the other SLRPs, lumican has a molecular weight of about 40 kilodaltons and has four major intramolecular domains:[9]

  1. a signal peptide of 16 amino acid residues;
  2. a negatively-charged N-terminal domain containing sulfated tyrosine and disulfide bond(s);
  3. ten tandem leucine-rich repeats allowing lumican to bind to other extracellular components such as collagen;
  4. a carboxyl terminal domain of 50 amino acid residues containing two conserved cysteines 32 residues apart.

There are four N-linked sites within the leucine-rich repeat domain of the protein core that can be substituted with keratan sulfate. The core protein of lumican (like decorin and fibromodulin) is horseshoe shaped. This enables it bind to collagen molecules within a collagen fibril, thus helping keep adjacent fibrils apart.[10]

Function

Lumican is a major keratan sulfate proteoglycan of the cornea but is ubiquitously distributed in most mesenchymal tissues throughout the body.[11] Lumican is involved in collagen fibril organization and circumferential growth, corneal transparency, and epithelial cell migration and tissue repair.[6] Corneal transparency is possible due to the exact alignment of collagen fibers by lumican (and keratocan) in the intrafibrillar space.

Clinical significance

Mice that have the lumican gene knocked out (Lum-/-) develop opacities of the cornea in both eyes and fragile skin.[12] The lumican (LUM) gene was thought to be a candidate susceptibility gene for high myopia; however, a meta-analysis showed no association between LUM polymorphism and high myopia susceptibility in all genetic models studied.[13]

Lum knockout mice also have abnormal

tendons six weeks after an injury.[16]

Lumican is present in the extracellular matrix of uteral tissues in fertile women.[17] There is an increase of lumican during the proliferative to secretory phase of the endometrium. In menopausal endometrial tissue, the level of lumican expression decreases and is also low in pathological compared to normal endometrium.

Lumican is highly expressed in pleural effusions (

tumor was associated with a reduction in metastatic recurrence after surgery and with a three-fold longer survival than patients without stromal lumican. As lumican can directly bind to and inhibit matrix metalloproteinase-14 (MMP14), lumican may limit tumor progression by preventing extracellular matrix collagen proteolysis by this enzyme.[20]

References

  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000139329Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000036446Ensembl, May 2017
  3. ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. PMID 1370446
    .
  6. ^ a b "Entrez Gene: LUM lumican".
  7. PMID 7558030
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Further reading