(cell and molecular biology) Any of a family of carbohydrate-binding, calcium-dependent cell adhesion molecules that play an important role in leukocyte-endothelial binding.
Selectin
| Sci-Tech Dictionary: selectin |
(sə′lek·tən)
| 5min Related Video: Selectins |
| Wikipedia: Selectin |
| Sushi domain (SCR repeat) | ||
|---|---|---|
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| P selectin lectin bound to sugar, shown in sticks, PDB 1G1R | ||
| Identifiers | ||
| Symbol | Sushi | |
| Pfam | PF00084 | |
| InterPro | IPR000436 | |
| SCOP | 1hfi | |
| Available PDB structures:
1hfh :870-926 1hfi :870-926 1cklF:99-157 1y8eA:86-143 1g40A:86-143 1g44C:86-143 1ridB:86-143 1e5gA:86-143 1h2qP:163-220 1ok2A:163-220 1ojyB:163-220 1h03P:163-220 1h04P:163-220 1ok1B:163-220 1h2pP:163-220 1upnE:163-220 1ojwB:163-220 1ojvA:163-220 1ok3A:163-220 1ok9B:163-220 1nwvA:163-220 1uotP:163-220 2a55A:113-170 1gkgA:1004-1061 1gknA:1004-1061 1gopA:1004-1061 1ppqA:1004-1061 1srzA:99-156 1ss2A:99-156 1qubA:84-137 1c1zA:84-137 1fhcA:1109-1163 1hr4A:162-223 1vvd :148-201 1vvc :148-201 1vve :148-201 1hcc :931-984 1ghqC:23-82 1ly2A:23-82 1kovA:389-442 1zjkA:300-361 1gpzB:309-371 1q3xA:366-430 1md7A:376-447 1md8A:376-447 1elvA:359-421 1z92B:24-82 1ilnA:24-82 1ilmA:24-82 2b5iD:24-82 |
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Selectins are a family of cell adhesion molecules (or CAMs). All selectins are single-chain transmembrane glycoproteins that share similar properties to C-type lectins due to a related amino terminus and calcium-dependent binding[1]. Selectins bind to sugar moieties and so are considered to be a type of lectin, cell adhesion proteins that bind sugar polymers.[2]
Contents |
Types
There are three subsets of selectins:
- E-selectin (in endothelial cells)
- L-selectin (in leukocytes)
- P-selectin (in platelets and endothelial cells)
Etymology
The name selectin comes from the words "selected" and "lectins," which are a type of carbohydrate-recognizing proteins.
Function
During an inflammatory response, stimuli such as histamine and thrombin cause endothelial cells to mobilize P-selectin from stores inside the cell to the cell surface. In addition, cytokines such as TNF-alpha stimulate the expression of E-selectin and additional P-selectin a few hours later.
As the leukocyte rolls along the blood vessel wall, the distal lectin-like domain of the selectin binds to certain carbohydrate groups presented on proteins (such as PSGL-1) on the leukocyte, which slows the cell and allows it to leave the blood vessel and enter the site of infection. The low-affinity nature of selectins is what allows the characteristic "rolling" action attributed to leukocytes during the leukocyte adhesion cascade[1].
The best-characterized ligand for the three selectins is P-selectin glycoprotein ligand-1 (PSGL-1), which is a mucin-type glycoprotein expressed on all white blood cells.
Neutrophils and eosinophils bind to E-selectin. One of the reported ligands for E-selectin is the sialylated Lewis X Ag (sLe(x)). Eosinophils, like neutrophils, use sialylated, protease-resistant structures to bind to E-selectin, although the eosinophil expresses much lower levels of these structures on its surface. [3] Ligands for P-selectin on eosinophils and neutrophils are similar sialylated, protease-sensitive, endo-beta-galactosidase-resistant structures, clearly different than those reported for E-selectin, and suggest disparate roles for P-selectin and E-selectin during recruitment during inflammatory responses. [4]
Research
Selectins are involved in significant biomedical research. One project involves using selectins in nanodevices to treat cancer. Researchers are trying to create a device capable of killing cancer cells circulating in the blood[5][6]. The scientists have covalently attached selectins to an epoxy surface in order to encourage tumor cells and other cells to roll. Also attached to the surface is a ligand that selectively signals cancer cells to undergo apoptosis, or cell death. Without selectins, the device would be unable to slow cancer cells down, and would thus be unable to kill them.
Selectins are also involved in projects to treat osteoporosis, a disease that occurs when bone-creating cells called osteoblasts become too scarce. Osteoblasts develop from stem cells, and scientists hope to eventually be able to treat osteoporosis by adding stem cells to a patient’s bone marrow. Researchers have developed a way to use selectins to direct stem cells introduced into the vascular system to the bone marrow[7]. E-selectins are constitutively expressed in the bone marrow, and researchers have shown that tagging stem cells with a certain glycoprotein causes these cells to migrate to the bone marrow. Thus, selectins may someday be essential to a regenerative therapy for osteoporosis[8].
Human proteins containing this domain
AGC1; APOH; BCAN; BF; C1R; C1S; C2; C4BPA; C4BPB; C6; C7; CD46; CD55; CFB; CFH; CFHR1; CFHR2; CFHR3; CFHR4; CFHR5; CR1; CR1L; CR2; CSMD1; CSMD2; CSMD3; CSPG3; DAF; F13B; FHR4; GABBR1; HP; IL2RA; KIAA0247; MASP1; MASP2; PAPPA; PAPPA2; RAMP; SEL-OB; SELE; SELL; SELP; SEZ6; SEZ6L; SEZ6L2; SNED1; SRPX; SRPX2; SUSD1; SUSD2; SUSD4; SVEP1; TPO; VCAN; psk-1; psk-2; psk-3;
External links
- CIMIT Center for Integration of Medicine and Innovative Technology
- Karp Lab on Research
- Sackstein Lab of Research
- Computer-generated movie of the mobilization of P-selectin inside a leukocyte at mcb.harvard.edu
References
- ^ a b Cotran; Kumar, Collins (1998). Robbins Pathologic Basis of Disease. Philadelphia: W.B Saunders Company. ISBN 0-7216-7335-X.
- ^ Parham,Peter.The Immune System. 2nd ed. Garland Science: New York, 2005. pg. 244-245
- ^ Bochner BS, Sterbinsky SA, Bickel CA, Werfel S, Wein M, Newman W. (January 15, 1994). "Differences between human eosinophils and neutrophils in the function and expression of sialic acid-containing counterligands for E-selectin". J Immunol. 152 (2): 774–82. PMID 7506734. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=7506734&query_hl=5&itool=pubmed_docsum.
- ^ Wein, M (1995). "Comparison of human eosinophil and neutrophil ligands for P-selectin: ligands for P-selectin differ from those for E-selectin". Am J Respir Cell Mol Biol. 12 (3): 315–9. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=7532979&query_hl=5&itool=pubmed_docsum.
- ^ In the lab of Jeffrey Karp of Harvard Medical School
- ^ Karp Lab
- ^ In the lab of Robert Sackstein Harvard University
- ^ Sackstein Lab
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