Illustration of the laminin-111 complex depicting the domain organization.

Laminins are a family of glycoproteins of the extracellular matrix of all animals. They are major constituents of the basement membrane, namely the basal lamina (the protein network foundation for most cells and organs). Laminins are vital to biological activity, influencing cell differentiation, migration, and adhesion.[1][2]

Laminins are heterotrimeric proteins with a high molecular mass (~400 to ~900 kDa) and possess three different chains (α, β and γ) encoded by five, four, and three paralogous genes in humans, respectively. The laminin molecules are named according to their chain composition, e.g. laminin-511 contains α5, β1, and γ1 chains.[3] Fourteen other chain combinations have been identified in vivo. The trimeric proteins intersect, composing a cruciform structure that is able to bind to other molecules of the extracellular matrix and cell membrane.[4] The three short arms have an affinity for binding to other laminin molecules, conducing sheet formation. The long arm is capable of binding to cells and helps anchor organized tissue cells to the basement membrane.

Laminins are integral to the structural scaffolding of almost every tissue of an organism—secreted and incorporated into cell-associated extracellular matrices. These glycoproteins are imperative to the maintenance and vitality of tissues; defective laminins can cause muscles to form improperly, leading to a form of muscular dystrophy, lethal skin blistering disease (junctional epidermolysis bullosa), and/or defects of the kidney filter (nephrotic syndrome).[5]

Types

In humans, fifteen laminin trimers have been identified. The laminins are combinations of different alpha-, beta-, and gamma-chains.[6]

Laminins were previously numbered as they were discovered, i.e. laminin-1, laminin-2, laminin-3, etc., but the nomenclature was changed to describe which chains are present in each isoform (laminin-111, laminin-211, etc.).[3] In addition, many laminins had common names before either laminin nomenclature was in place.[7][8]

Old nomenclature Old synonyms Chain composition New nomenclature
Laminin-1 EHS laminin α1β1γ1 Laminin-111
Laminin-2 Merosin α2β1γ1 Laminin-211
Laminin-3 S-laminin α1β2γ1 Laminin-121
Laminin-4 S-merosin α2β2γ1 Laminin-221
Laminin-5 / Laminin-5A Kalinin, epiligrin, nicein, ladsin α3Aβ3γ2 Laminin-332 / Laminin-3A32
Laminin-5B α3Bβ3γ2 Laminin-3B32
Laminin-6 / Laminin-6A K-laminin α3Aβ1γ1 Laminin-311 / Laminin-3A11
Laminin-7 / Laminin-7A KS-laminin α3Aβ2γ1 Laminin-321 / Laminin-3A21
Laminin-8 α4β1γ1 Laminin-411
Laminin-9 α4β2γ1 Laminin-421
Laminin-10 Drosophila-like laminin α5β1γ1 Laminin-511
Laminin-11 α5β2γ1 Laminin-521
Laminin-12 α2β1γ3 Laminin-213
Laminin-14 α4β2γ3 Laminin-423
α5β2γ2 Laminin-522
Laminin-15 α5β2γ3 Laminin-523

Function

Laminins form independent networks and are associated with type IV collagen networks via entactin,[9] fibronectin,[10] and perlecan. The proteins also bind to cell membranes through integrins and other plasma membrane molecules, such as the dystroglycan glycoprotein complex and Lutheran blood group glycoprotein.[4] Through these interactions, laminins critically contribute to cell attachment and differentiation, cell shape and movement, maintenance of tissue phenotype, and promotion of tissue survival.[4][6] Some of these biological functions of laminin have been associated with specific amino-acid sequences or fragments of laminin.[4] For example, the peptide sequence [GTFALRGDNGDNGQ], which is located on the alpha-chain of laminin, promotes the adhesion of endothelial cells.[11]

Laminin alpha4 is distributed in a variety of tissues including peripheral nerves, dorsal root ganglion, skeletal muscle and capillaries; in the neuromuscular junction, it is required for synaptic specialisation.[12] The structure of the laminin-G domain has been predicted to resemble that of pentraxin.[13]

Role in neural development

Laminin-111 is a major substrate along which nerve axons will grow, both in vivo and in vitro. For example, it lays down a path that developing retinal ganglion cells follow on their way from the retina to the tectum. It is also often used as a substrate in cell culture experiments. The presence of laminin-1 can influence how the growth cone responds to other cues. For example, growth cones are repelled by netrin when grown on laminin-111 but are attracted to netrin when grown on fibronectin. This effect of laminin-111 probably occurs through a lowering of intracellular cyclic AMP.

Role in peripheral nerve repair

Laminins are enriched at the lesion site after peripheral nerve injury and are secreted by Schwann cells. Neurons of the peripheral nervous system express integrin receptors that attach to laminins and promote neuroregeneration after injury.[14]

Pathology

Dysfunctional structure of one particular laminin, laminin-211, is the cause of one form of congenital muscular dystrophy.[15] Laminin-211 is composed of an α2, β1 and γ1 chains. This laminin's distribution includes the brain and muscle fibers. In muscle, it binds to alpha-dystroglycan and integrin alpha7—beta1 via the G domain, and via the other end, it binds to the extracellular matrix.

Abnormal laminin-332, which is essential for epithelial cell adhesion to the basement membrane, leads to a condition called junctional epidermolysis bullosa, characterized by generalized blisters, exuberant granulation tissue of skin and mucosa, and pitted teeth.

Malfunctional laminin-521 in the kidney filter causes leakage of protein into the urine and nephrotic syndrome.[5]

Role in cancer

Some of the laminin isoforms have been implicated in cancer pathophysiology. The majority of transcripts that harbor an internal ribosome entry site (IRES) are involved in cancer development via corresponding proteins. A crucial event in tumor progression referred to as epithelial to mesenchymal transition (EMT) allows carcinoma cells to acquire invasive properties. The translational activation of the extracellular matrix component laminin B1 (LAMB1) during EMT has been recently reported suggesting an IRES-mediated mechanism. In this study, the IRES activity of LamB1 was determined by independent bicistronic reporter assays. Strong evidences exclude an impact of cryptic promoter or splice sites on IRES-driven translation of LamB1. Furthermore, no other LamB1 mRNA species arising from alternative transcription start sites or polyadenylation signals were detected that account for its translational control. Mapping of the LamB1 5'-untranslated region (UTR) revealed the minimal LamB1 IRES motif between -293 and -1 upstream of the start codon. Notably, RNA affinity purification showed that the La protein interacts with the LamB1 IRES. This interaction and its regulation during EMT were confirmed by ribonucleoprotein immunoprecipitation. In addition, La was able to positively modulate LamB1 IRES translation. In summary, these data indicate that the LamB1 IRES is activated by binding to La which leads to translational upregulation during hepatocellular EMT.[16]

Use in cell culture

Together with other major components of the ECM, such as collagens and fibronectin, laminins have been used to enhance mammalian cell culture, especially in the case of pluripotent stem cells, as well as some primary cell cultures, which can be difficult to propagate on other substrates. Two types of naturally-sourced laminins are commercially available. Laminin-111 extracted from mouse sarcomas is one popular laminin type, as well as laminin mixtures from human placenta, which may primarily correspond to laminin-211, 411 or 511, depending on the provider.[17] The various laminin isoforms are practically impossible to isolate from tissues in pure form due to extensive cross-linking and the need for harsh extraction conditions, such as proteolytic enzymes or low pH, that cause degradation. Therefore, recombinant laminins have been produced since the year 2000.[18] This made it possible to test if laminins could have a significant role in vitro as they have in the human body. In 2008, two groups independently showed that mouse embryonic stem cells can be grown for months on top of recombinant laminin-511.[19][20] Later, Rodin et al. showed that recombinant laminin-511 can be used to create a totally xeno-free and defined cell culture environment to culture human pluripotent ES cells and human iPS cells.[21]

Laminin domains

Laminin Domain I
Identifiers
SymbolLaminin_I
PfamPF06008
InterProIPR009254
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary
Laminin Domain II
Identifiers
SymbolLaminin_II
PfamPF06009
InterProIPR010307
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary
Laminin B (Domain IV)
Identifiers
SymbolLaminin_B
PfamPF00052
InterProIPR000034
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary
Laminin EGF-like (Domains III and V)
crystal structure of three consecutive laminin-type epidermal growth factor-like (le) modules of laminin gamma1 chain harboring the nidogen binding site
Identifiers
SymbolLaminin_EGF
PfamPF00053
Pfam clanCL0001
InterProIPR002049
PROSITEPDOC00021
SCOP21tle / SCOPe / SUPFAM
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary
Laminin G domain
laminin alpha 2 chain lg4-5 domain pair, ca1 site mutant
Identifiers
SymbolLaminin_G_1
PfamPF00054
Pfam clanCL0004
InterProIPR012679
SCOP21qu0 / SCOPe / SUPFAM
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary
Laminin G domain
the structure of the ligand-binding domain of neurexin 1beta: regulation of lns domain function by alternative splicing
Identifiers
SymbolLaminin_G_2
PfamPF02210
Pfam clanCL0004
InterProIPR012680
SMARTTSPN
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary
Laminin N-terminal (Domain VI)
Identifiers
SymbolLaminin_N
PfamPF00055
Pfam clanCL0202
InterProIPR008211
SMARTLamNT
SCOP21klo / SCOPe / SUPFAM
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary

Laminins contain several conserved protein domains.

Laminin I and Laminin II

Laminins are trimeric molecules; laminin-1 is an alpha1 beta1 gamma1 trimer. It has been suggested that the domains I and II from laminin A, B1 and B2 may come together to form a triple helical coiled-coil structure.[22]

Laminin B

The laminin B domain (also known as domain IV) is an extracellular module of unknown function. It is found in a number of different proteins that include, heparan sulphate proteoglycan from basement membrane, a laminin-like protein from Caenorhabditis elegans and laminin. Laminin IV domain is not found in short laminin chains (alpha4 or beta3).

Laminin EGF-like

Beside different types of globular domains each laminin subunit contains, in its first half, consecutive repeats of about 60 amino acids in length that include eight conserved cysteines.[23] The tertiary structure of this domain is remotely similar in its N-terminus to that of the EGF-like module.[24][25] It is also known as a 'LE' or 'laminin-type EGF-like' domain. The number of copies of the laminin EGF-like domain in the different forms of laminins is highly variable; from 3 up to 22 copies have been found. In mouse laminin gamma-1 chain, the seventh LE domain has been shown to be the only one that binds with a high affinity to nidogen.[26] The binding-sites are located on the surface within the loops C1-C3 and C5-C6.[24][25] Long consecutive arrays of laminin EGF-like domains in laminins form rod-like elements of limited flexibility, which determine the spacing in the formation of laminin networks of basement membranes.[27][28]

Laminin G

The laminin globular (G) domain, also known as the LNS (Laminin-alpha, Neurexin and Sex hormone-binding globulin) domain, is on average 177 amino acids in length and can be found in one to six copies in various laminin family members as well as in a large number of other extracellular proteins.[29] For example, all laminin alpha-chains have five laminin G domains, all collagen family proteins have one laminin G domain, the CNTNAP proteins have four laminin G domains, while neurexin 1 and 2 each hold six laminin G domains. On average, approximately one quarter of the proteins that hold laminin G domains is taken up by these laminin G domains themselves. The smallest laminin G domain can be found in one of the collagen proteins (COL24A1; 77 AA) and the largest domain in TSPEAR (219 AA).

The exact function of the Laminin G domains has remained elusive, and a variety of binding functions has been ascribed to different Laminin G modules. For example, the laminin alpha1 and alpha2 chains each have five C-terminal laminin G domains, where only domains LG4 and LG5 contain binding sites for heparin, sulphatides and the cell surface receptor dystroglycan.[30] Laminin G-containing proteins appear to have a wide variety of roles in cell adhesion, signalling, migration, assembly and differentiation.

Laminin N-terminal

Basement membrane assembly is a cooperative process in which laminins polymerise through their N-terminal domain (LN or domain VI) and anchor to the cell surface through their G domains. Netrins may also associate with this network through heterotypic LN domain interactions.[28] This leads to cell signalling through integrins and dystroglycan (and possibly other receptors) recruited to the adherent laminin. This LN domain-dependent self-assembly is considered to be crucial for the integrity of basement membranes, as highlighted by genetic forms of muscular dystrophy containing the deletion of the LN module from the alpha 2 laminin chain.[31] The laminin N-terminal domain is found in all laminin and netrin subunits except laminin alpha 3A, alpha 4 and gamma 2.

Human proteins containing laminin domains

See also

References

  1. ↑ Timpl R, Rohde H, Robey PG, Rennard SI, Foidart JM, Martin GR (October 1979). "Laminin--a glycoprotein from basement membranes". The Journal of Biological Chemistry. 254 (19): 9933–7. doi:10.1016/S0021-9258(19)83607-4. PMID 114518.
  2. ↑ Durbeej, Madeleine (January 2010). "Laminins". Cell and Tissue Research. 339 (1): 259–268. doi:10.1007/s00441-009-0838-2. ISSN 1432-0878. PMID 19693542 – via Springer Link.
  3. 1 2 Aumailley M, Bruckner-Tuderman L, Carter WG, Deutzmann R, Edgar D, Ekblom P, Engel J, Engvall E, Hohenester E, Jones JC, Kleinman HK, Marinkovich MP, Martin GR, Mayer U, Meneguzzi G, Miner JH, Miyazaki K, Patarroyo M, Paulsson M, Quaranta V, Sanes JR, Sasaki T, Sekiguchi K, Sorokin LM, Talts JF, Tryggvason K, Uitto J, Virtanen I, von der Mark K, Wewer UM, Yamada Y, Yurchenco PD (August 2005). "A simplified laminin nomenclature". Matrix Biology. 24 (5): 326–32. doi:10.1016/j.matbio.2005.05.006. PMID 15979864.
  4. 1 2 3 4 M. A. Haralson; John R. Hassell (1995). Extracellular matrix: a practical approach. Ithaca, N.Y: IRL Press. ISBN 978-0-19-963220-6.
  5. 1 2 Yurchenco PD, Patton BL (2009). "Developmental and pathogenic mechanisms of basement membrane assembly". Current Pharmaceutical Design. 15 (12): 1277–94. doi:10.2174/138161209787846766. PMC 2978668. PMID 19355968.
  6. 1 2 Colognato H, Yurchenco PD (June 2000). "Form and function: the laminin family of heterotrimers". Developmental Dynamics. 218 (2): 213–34. doi:10.1002/(SICI)1097-0177(200006)218:2<213::AID-DVDY1>3.0.CO;2-R. PMID 10842354.
  7. ↑ Royce, Peter M., ed. (2002). Connective tissue and its heritable disorders: molecular, genetic, and medical aspects (2nd ed.). New York: Wiley-Liss. p. 306. ISBN 9780471251859.
  8. ↑ Kühn, Klaus (1997). "Extracellular matrix constituents as integrin ligands". In Elbe, Johannes A. (ed.). Integrin-ligand interaction. New York: Chapman & Hall. p. 50. ISBN 9780412138614.
  9. ↑ Smith J, Ockleford CD (January 1994). "Laser scanning confocal examination and comparison of nidogen (entactin) with laminin in term human amniochorion". Placenta. 15 (1): 95–106. doi:10.1016/S0143-4004(05)80240-1. PMID 8208674.
  10. ↑ Ockleford C, Bright N, Hubbard A, D'Lacey C, Smith J, Gardiner L, Sheikh T, Albentosa M, Turtle K (October 1993). "Micro-trabeculae, macro-plaques or mini-basement membranes in human term fetal membranes?". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 342 (1300): 121–36. doi:10.1098/rstb.1993.0142. PMID 7904354.
  11. ↑ Beck et al., 1999.
  12. ↑ Ichikawa N, Kasai S, Suzuki N, Nishi N, Oishi S, Fujii N, Kadoya Y, Hatori K, Mizuno Y, Nomizu M, Arikawa-Hirasawa E (April 2005). "Identification of neurite outgrowth active sites on the laminin alpha4 chain G domain". Biochemistry. 44 (15): 5755–62. doi:10.1021/bi0476228. PMID 15823034.
  13. ↑ Beckmann G, Hanke J, Bork P, Reich JG (February 1998). "Merging extracellular domains: fold prediction for laminin G-like and amino-terminal thrombospondin-like modules based on homology to pentraxins". Journal of Molecular Biology. 275 (5): 725–30. doi:10.1006/jmbi.1997.1510. PMID 9480764.
  14. ↑ Nieuwenhuis, B.; Haenzi, B.; Andrews, M. R.; Verhaagen, J.; Fawcett, J. W. (2018). "Integrins promote axonal regeneration after injury of the nervous system". Biological Reviews. 93 (3): 1339–1362. doi:10.1111/brv.12398. PMC 6055631. PMID 29446228.
  15. ↑ Hall TE, Bryson-Richardson RJ, Berger S, Jacoby AS, Cole NJ, Hollway GE, Berger J, Currie PD (April 2007). "The zebrafish candyfloss mutant implicates extracellular matrix adhesion failure in laminin alpha2-deficient congenital muscular dystrophy". Proceedings of the National Academy of Sciences of the United States of America. 104 (17): 7092–7. Bibcode:2007PNAS..104.7092H. doi:10.1073/pnas.0700942104. PMC 1855385. PMID 17438294.
  16. ↑ Petz M, Them N, Huber H, Beug H, Mikulits W (January 2012). "La enhances IRES-mediated translation of laminin B1 during malignant epithelial to mesenchymal transition". Nucleic Acids Research. 40 (1): 290–302. doi:10.1093/nar/gkr717. PMC 3245933. PMID 21896617.
  17. ↑ Wondimu Z, Gorfu G, Kawataki T, Smirnov S, Yurchenco P, Tryggvason K, Patarroyo M (March 2006). "Characterization of commercial laminin preparations from human placenta in comparison to recombinant laminins 2 (alpha2beta1gamma1), 8 (alpha4beta1gamma1), 10 (alpha5beta1gamma1)". Matrix Biology. 25 (2): 89–93. doi:10.1016/j.matbio.2005.10.001. PMID 16289578.
  18. ↑ Kortesmaa, Jarkko; Yurchenco, Peter; Tryggvason, Karl (19 May 2000). "Recombinant Laminin-8 (α4β1γ1)". Journal of Biological Chemistry. 275 (20): 14853–14859. doi:10.1074/jbc.275.20.14853. PMID 10809728.
  19. ↑ Domogatskaya A, Rodin S, Boutaud A, Tryggvason K (November 2008). "Laminin-511 but not -332, -111, or -411 enables mouse embryonic stem cell self-renewal in vitro". Stem Cells. 26 (11): 2800–9. doi:10.1634/stemcells.2007-0389. PMID 18757303.
  20. ↑ Miyazaki T, Futaki S, Hasegawa K, Kawasaki M, Sanzen N, Hayashi M, Kawase E, Sekiguchi K, Nakatsuji N, Suemori H (October 2008). "Recombinant human laminin isoforms can support the undifferentiated growth of human embryonic stem cells". Biochemical and Biophysical Research Communications. 375 (1): 27–32. doi:10.1016/j.bbrc.2008.07.111. PMID 18675790.
  21. ↑ Rodin S, Domogatskaya A, Ström S, Hansson EM, Chien KR, Inzunza J, Hovatta O, Tryggvason K (June 2010). "Long-term self-renewal of human pluripotent stem cells on human recombinant laminin-511". Nature Biotechnology. 28 (6): 611–5. doi:10.1038/nbt.1620. hdl:10616/40259. PMID 20512123. S2CID 10801152.
  22. ↑ Sasaki M, Kleinman HK, Huber H, Deutzmann R, Yamada Y (November 1988). "Laminin, a multidomain protein. The A chain has a unique globular domain and homology with the basement membrane proteoglycan and the laminin B chains". The Journal of Biological Chemistry. 263 (32): 16536–44. doi:10.1016/S0021-9258(18)37424-6. PMID 3182802.
  23. ↑ Engel J (July 1989). "EGF-like domains in extracellular matrix proteins: localized signals for growth and differentiation?". FEBS Letters. 251 (1–2): 1–7. doi:10.1016/0014-5793(89)81417-6. PMID 2666164. S2CID 36607427.
  24. 1 2 Stetefeld J, Mayer U, Timpl R, Huber R (April 1996). "Crystal structure of three consecutive laminin-type epidermal growth factor-like (LE) modules of laminin gamma1 chain harboring the nidogen binding site". Journal of Molecular Biology. 257 (3): 644–57. doi:10.1006/jmbi.1996.0191. PMID 8648630.
  25. 1 2 Baumgartner R, Czisch M, Mayer U, Pöschl E, Huber R, Timpl R, Holak TA (April 1996). "Structure of the nidogen binding LE module of the laminin gamma1 chain in solution". Journal of Molecular Biology. 257 (3): 658–68. doi:10.1006/jmbi.1996.0192. PMID 8648631.
  26. ↑ Mayer U, Pöschl E, Gerecke DR, Wagman DW, Burgeson RE, Timpl R (May 1995). "Low nidogen affinity of laminin-5 can be attributed to two serine residues in EGF-like motif gamma 2III4". FEBS Letters. 365 (2–3): 129–32. doi:10.1016/0014-5793(95)00438-F. PMID 7781764. S2CID 21559588.
  27. ↑ Beck K, Hunter I, Engel J (February 1990). "Structure and function of laminin: anatomy of a multidomain glycoprotein". FASEB Journal. 4 (2): 148–60. doi:10.1096/fasebj.4.2.2404817. PMID 2404817.
  28. 1 2 Yurchenco PD, Cheng YS (August 1993). "Self-assembly and calcium-binding sites in laminin. A three-arm interaction model". The Journal of Biological Chemistry. 268 (23): 17286–99. doi:10.1016/S0021-9258(19)85334-6. PMID 8349613.
  29. ↑ "Laminin G domain". InterPro. European Bioinformatics Institute. Retrieved 22 February 2016.
  30. ↑ Tisi D, Talts JF, Timpl R, Hohenester E (April 2000). "Structure of the C-terminal laminin G-like domain pair of the laminin alpha2 chain harbouring binding sites for alpha-dystroglycan and heparin". The EMBO Journal. 19 (7): 1432–40. doi:10.1093/emboj/19.7.1432. PMC 310212. PMID 10747011.
  31. ↑ Xu H, Wu XR, Wewer UM, Engvall E (November 1994). "Murine muscular dystrophy caused by a mutation in the laminin alpha 2 (Lama2) gene". Nature Genetics. 8 (3): 297–302. doi:10.1038/ng1194-297. PMID 7874173. S2CID 21549628.
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