Elastin

Source: Wikipedia, the free encyclopedia.
ELN
Identifiers
Gene ontology
Molecular function
Cellular component
Biological process
Sources:Amigo / QuickGO
Ensembl

ENSG00000049540

n/a

UniProt

P15502

n/a

RefSeq (mRNA)

n/a

RefSeq (protein)

n/a

Location (UCSC)Chr 7: 74.03 – 74.07 Mbn/a
PubMed search[2]n/a
Wikidata
View/Edit Human
Thick elastic fibers consisting of bundles of elastin in the human lung

Elastin is a

gnathostomes (jawed vertebrates).[3] It is highly elastic and present in connective tissue allowing many tissues in the body to resume their shape after stretching or contracting.[4] Elastin helps skin to return to its original position when it is poked or pinched. Elastin is also an important load-bearing tissue in the bodies of vertebrates and used in places where mechanical energy is required to be stored.[5]

Function

The ELN gene encodes a protein that is one of the two components of

hydrophobic amino acids such as glycine and proline, which form mobile hydrophobic regions bounded by crosslinks between lysine residues.[6] Multiple transcript variants encoding different isoforms have been found for this gene.[6] Elastin's soluble precursor is tropoelastin.[7] The characterization of disorder is consistent with an entropy-driven mechanism of elastic recoil. It is concluded that conformational disorder is a constitutive feature of elastin structure and function.[8]

Clinical significance

Deletions and mutations in this gene are associated with

Menkes syndrome, pseudoxanthoma elasticum, and Williams syndrome.[9]

Elastosis

Elastosis is the buildup of elastin in tissues, and is a form of degenerative disease.[10] There are a multitude of causes, but the most commons cause is actinic elastosis of the skin, also known as solar elastosis, which is caused by prolonged and excessive sun exposure, a process known as photoaging. Uncommon causes of skin elastosis include elastosis perforans serpiginosa, perforating calcific elastosis and linear focal elastosis.[10]

Skin elastosis causes
Condition Distinctive features Histopathology
Actinic elastosis
(most common, also called solar elastosis) 		Elastin replacing collagen fibers of the
reticular dermis
Elastosis perforans serpiginosa Degenerated elastic fibers and transepidermal perforating canals (arrow in image points at one of them)[11]
Perforating calcific elastosis Clumping of short elastic fibers in the dermis.[11]
Linear focal elastosis Accumulation of fragmented elastotic material within the papillary dermis and transcutaneous elimination of elastotic fibers.[11]

Composition

Stretched elastin isolated from bovine aorta

In the body, elastin is usually associated with other proteins in connective tissues. Elastic fiber in the body is a mixture of amorphous elastin and fibrous fibrillin. Both components are primarily made of smaller amino acids such as glycine, valine, alanine, and proline.[9][12] The total elastin ranges from 58 to 75% of the weight of the dry defatted artery in normal canine arteries.[13] Comparison between fresh and digested tissues shows that, at 35% strain, a minimum of 48% of the arterial load is carried by elastin, and a minimum of 43% of the change in stiffness of arterial tissue is due to the change in elastin stiffness.[14]

Tissue distribution

Elastin serves an important function in

jawed vertebrates.[15]

Characteristics

Elastin is a very long-lived protein, with a half-life of over 78 years in humans.[16]

Clinical research

The feasibility of using recombinant human tropoelastin to enable elastin fiber production to improve skin flexibility in wounds and scarring has been studied.[17][18] After subcutaneous injections of recombinant human tropoelastin into fresh wounds it was found there was no improvement in scarring or the flexibility of the eventual scarring.[17][18]

Biosynthesis

Tropoelastin precursors

Elastin is made by linking together many small

kDa), to make the final massive, insoluble, durable complex. The unlinked tropoelastin molecules are not normally available in the cell, since they become crosslinked into elastin fibres immediately after their synthesis by the cell and export into the extracellular matrix.[19]

Each tropoelastin consists of a string of 36 small

hydrophilic domains, which are encoded by separate exons
, so that the domain structure of tropoelastin reflects the exon organization of the gene. The hydrophilic domains contain Lys-Ala (KA) and Lys-Pro (KP) motifs that are involved in crosslinking during the formation of mature elastin. In the KA domains, lysine residues occur as pairs or triplets separated by two or three alanine residues (e.g. AAAKAAKAA) whereas in KP domains the lysine residues are separated mainly by proline residues (e.g. KPLKP).

Aggregation

Tropoelastin aggregates at physiological temperature due to interactions between hydrophobic domains in a process called

coacervation. This process is reversible and thermodynamically controlled and does not require protein cleavage. The coacervate is made insoluble by irreversible
crosslinking.

Crosslinking

To make mature elastin fibres, the tropoelastin molecules are cross-linked via their lysine residues with desmosine and isodesmosine cross-linking molecules. The enzyme that performs the crosslinking is lysyl oxidase, using an in vivo Chichibabin pyridine synthesis reaction.[20]

Molecular biology

Domain structure of human tropoelastin

In mammals, the

transcription start sites
.

Tissue specific variants of elastin are produced by alternative splicing of the tropoelastin gene. There are at least 11 known human tropoelastin isoforms. these isoforms are under developmental regulation, however there are minimal differences among tissues at the same developmental stage.[9]

See also

References

  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000049540 – Ensembl, May 2017
  2. ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  3. PMID 15837523
    .
  4. S2CID 196458819
    .
  5. S2CID 8274849
    .
  6. ^ a b c "Entrez Gene: elastin".
  7. ^ "Elastin (ELN)". Archived from the original on 13 March 2017. Retrieved 31 October 2011.
  8. PMID 20453927
    .
  9. ^
    PMID 9851686
    .
  10. ^ a b Wright B. "Elastosis". DermNet NZ.
  11. ^
    PMID 24278718.
    -Creative Commons Attribution 3.0 Unported
    license
  12. PMID 12082143
    .
  13. PMID 5914851
    .
  14. PMID 18660454
    .
  15. PMID 868643
    .
  16. PMID 23258296
    .
  17. ^
    PMID 31936277
    .
  18. ^
    S2CID 39251937
    .
  19. PMID 28380679
    .
  20. PMID 11278561
    .

Further reading

External links

This article incorporates text from the United States National Library of Medicine, which is in the public domain.

Retrieved from "https://en.wikipedia.org/w/index.php?title=Elastin&oldid=1175058152"