Jump to content

Substrate adhesion molecules

From Wikipedia, the free encyclopedia
An image illustrating the two main SAMs: Integrin and CD44. Extracellular domains are red in hue, transmembrane domains are blue, and intracellular domains are green. Other molecules that coordinate with the SAMs are depicted, including ECM elements like fibrin and collagen, effector molecules, and actin. The alpha and beta subunits of integrin bind to the ECM elements, while the beta subunit is bound to actin on the intracellular side via talin and vinculin. CD44 is hook-shaped, binding colorful effector molecules. One aids CD44 in binding to actin.
The substrate adhesion molecules integrin and CD44. Both are bound to extracellular matrix elements like fibronectin or collagen. Integrins have an α- and a β- subunit, the latter of which binds to actin with the aid of talin and vinculin. CD44 binds effector molecules to trigger cell signaling cascades. Extracellular, transmembrane, and intracellular domains are red, blue, and green, respectively.

Substrate adhesion molecules (SAMs), also known as cell-substrate adhesion molecules, cell-substratum adhesion molecules, substratum adhesion molecules, or cell-matrix molecules,[1] are single-pass membrane proteins characterized by their role in binding cells to the extracellular matrix (ECM).[2]

As it is commonly understood that individual members of this family bind ECM elements, publications often forego the SAM classification and will instead refer to these proteins under the broader classification for proteins involved in adhesion, cell adhesion molecules.

Examples

[edit]

Structure

[edit]

The intracellular side will be anchored to the cytoskeleton (actin, in the case of integrins), while the substrate side will anchor to the ECM.

Integrins have two subunits, an α and a β. Both bind to the ECM on the substrate side, which activates the actin-binding activity of the β unit on the intracellular side.[5] This forms what is called a focal adhesion, which enables external activity in the extracellular matrix to affect the shape and movement of the cell.[6]

CD44 only has one subunit, with a long substrate-side N-terminal head and a short intracellular tail. The extracellular domain can bind many different molecules, including those composing the ECM. The intracellular domain can then bind with various effector proteins, including actin.[7] CD44 is primarily involved in signaling.

Relevance in Biology

[edit]

Neuronal Morphogenesis

[edit]

SAMs play a key role in neuronal morphogenesis.[8] Integrin organizes actin to aid in synaptic stability, synaptic plasticity, and dendritic stability on the dendritic end of a neuron. On the axonal end, focal adhesions are formed to aid the axon terminal in locomotion towards the proper location.[9]

Cancer Markers

[edit]

CD44 is a prominent cancer marker because it plays many important roles in cancer pathology. It can trigger the digestion of the ECM to allow metastasis, trigger angiogenesis, inhibit the P53 apoptosis monitoring system, and, when bound to hyaluronic acid, trigger the MAPK cascade to promote proliferation.[10]

See also

[edit]

References

[edit]
  1. ^ Pignatelli, Massimo; Vessey BM, Carina J. (September 1994). "Adhesion molecules: Novel molecular tools in tumor pathology". Human Pathology. 25 (9): 849–856. doi:10.1016/0046-8177(94)90002-7. PMID 8088758.
  2. ^ Schwab, Manfred, ed. (2001). "Cell Adhesion Molecules". Encyclopedic reference of cancer, Volume 1. Springer. p. 183. ISBN 978-3-540-66527-4.
  3. ^ Murray, P.; Frampton, G; Nelson, P. (1999-08-07). "Cell adhesion molecules". BMJ. 319 (7206): 332–334. doi:10.1136/bmj.319.7206.332. ISSN 0959-8138. PMC 1126974. PMID 10435939.
  4. ^ Pignatelli, Massimo; Vessey BM, Carina J. (September 1994). "Adhesion molecules: Novel molecular tools in tumor pathology". Human Pathology. 25 (9): 849–856. doi:10.1016/0046-8177(94)90002-7. PMID 8088758.
  5. ^ "13.6: Integrins". Biology LibreTexts. 2018-12-18. Retrieved 2024-12-07.
  6. ^ Barry, John Michael (2002). Molecular embryology: how molecules give birth to animals. Taylor & Francis. p. 30. ISBN 978-1-56032-936-7.
  7. ^ Dzwonek, Joanna; Wilczynski, Grzegorz M. (2015-05-07). "CD44: molecular interactions, signaling and functions in the nervous system". Frontiers in Cellular Neuroscience. 9: 175. doi:10.3389/fncel.2015.00175. ISSN 1662-5102. PMC 4423434. PMID 25999819.
  8. ^ Kollins, Katherine M.; Davenport, Roger W. (2006). "Branching morphogenesis in vertebrate neurons". In Davies, Jamie A. (ed.). Branching morphogenesis. Birkhäuser. p. 24. ISBN 978-0-387-25615-3.
  9. ^ Lilja, Johanna; Ivaska, Johanna (2018-06-15). "Integrin activity in neuronal connectivity". Journal of Cell Science. 131 (12): jcs212803. doi:10.1242/jcs.212803. ISSN 0021-9533. PMID 29907643.
  10. ^ Xu, Hanxiao; Niu, Mengke; Yuan, Xun; Wu, Kongming; Liu, Aiguo (2020-12-10). "CD44 as a tumor biomarker and therapeutic target". Experimental Hematology & Oncology. 9 (1): 36. doi:10.1186/s40164-020-00192-0. ISSN 2162-3619. PMC 7727191. PMID 33303029.

Further reading

[edit]