Elastic fibers(oryellow fibers) are an essential component of theextracellular matrixcomposed of bundles ofproteins(elastin) which are produced by a number of different cell types including fibroblasts, endothelial, smooth muscle, and airway epithelial cells.[1]These fibers are able to stretch many times their length, and snap back to their original length when relaxed without loss of energy. Elastic fibers includeelastin,elauninandoxytalan.
| Elastic fiber | |
|---|---|
 Subcutaneous tissue from a young rabbit. Highly magnified. (Elastic fibers labeled at right) | |
| Identifiers | |
| FMA | 63868 |
| Anatomical terminology | |
Elastic fibers are formed viaelastogenesis,[2][3]a highly complex process involving several key proteins including fibulin-4, fibulin-5, latent transforming growth factor β binding protein 4, and microfibril associated protein 4.[4][5][6][7]In this processtropoelastin,the soluble monomeric precursor to elastic fibers is produced by elastogenic cells and chaperoned to the cell surface. Following excretion from the cell, tropoelastin self associates into ~200 nm particles by coacervation, an entropically driven process involving interactions between tropoelastin's hydrophobic domains, which is mediated byglycosaminoglycans,heparan, and other molecules.[8][9][10]These particles then fuse to give rise to 1-2 micron spherules which continue to grow as they move down from the cells surface before being deposited ontofibrillinmicrofibrillar scaffolds.[1]
Following deposition onto microfibrils tropoelastin is insolubilized via extensive crosslinking by members of thelysyl oxidaseand lysyl oxidase like family of copper-dependent amine oxidases into amorphouselastin,a highly resilient, insoluble polymer that is metabolically stable over a human lifespan.[1]These two families of enzymes react with the manylysineresidues present in tropoelastin to form reactivealdehydesandallysineviaoxidative deamination.[11]
These reactive aldehydes and allysines can react with other lysine and allysine residues to formdesmosine,isodesmosine,and a number of other polyfunctional crosslinks that join surrounding molecules of tropoelastin into an extensively crosslinked elastin matrix. This process creates a diverse array of intramolecular and intermolecularcrosslinks[12]These unique crosslinks are responsible for elastin's durability and persistence. Maintenance of crosslinked elastin is carried out by a number of proteins including lysyl oxidase-like 1 protein.[13]
Mature elastic fibers consist of an amorphouselastincore surrounded by a glycosaminoglycans, heparan sulphate,[14]and number of other proteins such as microfibrillar-associatedglycoproteins,fibrillin,fibullin,and theelastin receptor.
Distribution
edit
Elastic fibers are found in theskin,lungs,arteries,veins,connective tissue proper,elastic cartilage,periodontal ligament,fetaltissueand other tissues which must undergo mechanical stretching.[1]In the lung there are thick and thin elastic fibers.[3]
Elastic fibers are absent fromscarring,keloidsanddermatofibromasand they are decreased greatly, or are absent inanetodermas.[15]
Histology
editElastic fibers stain well withaldehyde fuchsin,orcein,[16]andWeigert's elastic staininhistologicalsections.
Thepermanganate-bisulfite-toluidine bluereaction is a highly selective and sensitive method for demonstrating elastic fibers under polarizing optics. The inducedbirefringencedemonstrates the highly ordered molecular structure of the elastin molecules in the elastic fiber. This is not readily apparent under normal optics.
Defects and disease
editThere is evidence to believe that certain defects of any components of the elastic matrix may impair and alter the structural appearance of elastic andcollagenfibers.
Cutis laxaandWilliams syndromehave elastic matrix defects that have been directly associated with alterations in the elastin gene.
Alpha-1 antitrypsin deficiencyis a genetic disorder where elastin is excessively degraded byelastase,a degrading protein released byneutrophilsduring the inflammatory response. This leads most often toemphysemaand liver disease in affected individuals.
Buschke–Ollendorff syndrome,Menkes disease,pseudoxanthoma elasticum,andMarfan's syndromehave been associated with defects in copper metabolism and lysyl oxidase or defects in the microfibril (defects infibrillin,orfibullinfor example).
Hurler disease,alysosomalstorage disease, is associated with an altered elastic matrix.
Hypertensionand somecongenital heart defectsare associated with alterations in thegreat arteries,arteries,andarterioleswith alterations in the elastic matrix.
Elastosis
editElastosisis the buildup of elastic fibers in tissues, and is a form ofdegenerative disease.[17]There are a multitude of causes, but the most commons cause isactinic elastosisof the skin, also known assolar elastosis,which is caused by prolonged and excessive sun exposure, a process known asphotoaging.Uncommon causes of skin elastosis includeelastosis perforans serpiginosa,perforating calcific elastosisandlinear focal elastosis.[17]
| Condition | Distinctive features | Histopathology |
|---|---|---|
| Actinic elastosis (most common, also called solar elastosis) |
Elastin replacing collagen fibers of thepapillary dermisandreticular dermis | 
|
| Elastosis perforans serpiginosa | Degenerated elastic fibers and transepidermal perforating canals (arrow in image points at one of them)[18] | 
|
| Perforating calcific elastosis | Clumping of short elastic fibers in the dermis.[18] | 
|
| Linear focal elastosis | Accumulation of fragmented elastotic material within the papillary dermis and transcutaneous elimination of elastotic fibers.[18] | 
|
See also
editReferences
edit- ^abcdVindin H, Mithieux SM, Weiss AS (November 2019). "Elastin architecture".Matrix Biology.84:4–16.doi:10.1016/j.matbio.2019.07.005.PMID31301399.S2CID196458819.
- ^Mithieux SM, Weiss AS (2005). "Elastin".Advances in Protein Chemistry.70.Elsevier: 437–61.doi:10.1016/s0065-3233(05)70013-9.ISBN978-0-12-034270-9.PMID15837523.
- ^abThunnissen E, Motoi N, Minami Y, Matsubara D, Timens W, Nakatani Y, Ishikawa Y, Baez-Navarro X, Radonic T, Blaauwgeers H, Borczuk AC, Noguchi M (August 2021)."Elastin in pulmonary pathology: relevance in tumours with a lepidic or papillary appearance. A comprehensive understanding from a morphological viewpoint".Histopathology.80(3): 457–467.doi:10.1111/his.14537.PMC9293161.PMID34355407.
- ^Robertson IB, Horiguchi M, Zilberberg L, Dabovic B, Hadjiolova K, Rifkin DB (September 2015)."Latent TGF-β-binding proteins".Matrix Biology.47:44–53.doi:10.1016/j.matbio.2015.05.005.PMC4844006.PMID25960419.
- ^Pilecki B, Holm AT, Schlosser A, Moeller JB, Wohl AP, Zuk AV, et al. (January 2016)."Characterization of Microfibrillar-associated Protein 4 (MFAP4) as a Tropoelastin- and Fibrillin-binding Protein Involved in Elastic Fiber Formation".The Journal of Biological Chemistry.291(3): 1103–14.doi:10.1074/jbc.M115.681775.PMC4714194.PMID26601954.
- ^Dabovic B, Chen Y, Choi J, Vassallo M, Dietz HC, Ramirez F, et al. (April 2009)."Dual functions for LTBP in lung development: LTBP-4 independently modulates elastogenesis and TGF-beta activity".Journal of Cellular Physiology.219(1): 14–22.doi:10.1002/jcp.21643.PMC2719250.PMID19016471.
- ^Nakamura T, Lozano PR, Ikeda Y, Iwanaga Y, Hinek A, Minamisawa S, et al. (January 2002). "Fibulin-5/DANCE is essential for elastogenesis in vivo".Nature.415(6868): 171–5.doi:10.1038/415171a.PMID11805835.S2CID4343659.
- ^Yeo GC, Keeley FW, Weiss AS (September 2011). "Coacervation of tropoelastin".Advances in Colloid and Interface Science.167(1–2): 94–103.doi:10.1016/j.cis.2010.10.003.PMID21081222.
- ^Wu WJ, Vrhovski B, Weiss AS (July 1999)."Glycosaminoglycans mediate the coacervation of human tropoelastin through dominant charge interactions involving lysine side chains".The Journal of Biological Chemistry.274(31): 21719–24.doi:10.1074/jbc.274.31.21719.PMID10419484.
- ^Tu Y, Weiss AS (July 2008). "Glycosaminoglycan-mediated coacervation of tropoelastin abolishes the critical concentration, accelerates coacervate formation, and facilitates spherule fusion: implications for tropoelastin microassembly".Biomacromolecules.9(7): 1739–44.doi:10.1021/bm7013153.PMID18547105.
- ^Lucero HA, Kagan HM (October 2006)."Lysyl oxidase: an oxidative enzyme and effector of cell function".Cellular and Molecular Life Sciences.63(19–20): 2304–16.doi:10.1007/s00018-006-6149-9.PMC11136443.PMID16909208.S2CID31863161.
- ^Schräder CU, Heinz A, Majovsky P, Karaman Mayack B, Brinckmann J, Sippl W, Schmelzer CE (September 2018)."Elastin is heterogeneously cross-linked".The Journal of Biological Chemistry.293(39): 15107–15119.doi:10.1074/jbc.RA118.004322.PMC6166741.PMID30108173.
- ^Liu X, Zhao Y, Gao J, Pawlyk B, Starcher B, Spencer JA, et al. (February 2004)."Elastic fiber homeostasis requires lysyl oxidase-like 1 protein".Nature Genetics.36(2): 178–82.doi:10.1038/ng1297.PMID14745449.
- ^Gheduzzi D, Guerra D, Bochicchio B, Pepe A, Tamburro AM, Quaglino D, et al. (February 2005). "Heparan sulphate interacts with tropoelastin, with some tropoelastin peptides and is present in human dermis elastic fibers".Matrix Biology.24(1): 15–25.doi:10.1016/j.matbio.2004.12.001.PMID15748998.
- ^Ackerman AB, Böer A, Bennin B, Gottlieb GJ (January 2005).Histologic Diagnosis of Inflammatory Skin Diseases An Algorithmic Method Based on Pattern Analysis: Embryologic, Histologic, and Anatomic Aspects: Elastic Fibers(Third ed.). Ardor Scribendi. p. 522.ISBN9781893357259.Archived fromthe originalon June 20, 2018.RetrievedDecember 28,2016.
Elastic fibers are absent from scarring processes such as scars, keloids, and dermatofibromas
- ^"Connective Tissue".Archived fromthe originalon November 7, 2008.
- ^abWright B."Elastosis".DermNet NZ.
- ^abcHosen MJ, Lamoen A, De Paepe A, Vanakker OM (2012)."Histopathology of pseudoxanthoma elasticum and related disorders: histological hallmarks and diagnostic clues".Scientifica.2012:598262.doi:10.6064/2012/598262.PMC3820553.PMID24278718.
-Creative Commons Attribution 3.0 Unportedlicense
External links
edit- Histology image: 00801ooa– Histology Learning System at Boston University - "Connective Tissue elastic fibers"
- UIUC Histology Subject328
- Anatomy photo: TermsCells&Tissues/connective/elastic/elastic2- Comparative Organology at University of California, Davis - "Connective tissue, elastic (LM, High)"