Name: selectins in immune cell capture
Uploaded: 2023-04-30T11:56:02.000Z
Duration: 1 min 25 s
Channel: JoVE

Selectins are cell surface glycoproteins that bind carbohydrate ligands and participate in transient cell-cell adhesion.
All selectins comprise an N-terminal lectin domain and an epidermal growth factor or EGF domain that regulate binding specificity and strength.
However, the number of sequence-conserved-repeats or SCR domains can vary from two to nine repeats depending on the type of selectin.
The short L-selectins expressed on immune cells like lymphocytes help them migrate into lymph nodes by binding ligands on the endothelial cells.
The larger P-selectins are primarily expressed on platelets. They aid in aggregating platelets and immune cells at the site of injury.
A third type, called E-selectins, is temporally expressed along with P-selectins on endothelial cells during an immune response.
These selectins form weak, transient interactions with free-flowing leukocytes and slow them down.
The leukocytes then roll along the endothelial surface, where other cell adhesion molecules help recruit them to the appropriate tissue microenvironments &#8212; a process called leukocyte homing.

selecties

Selectins

Celadhesie is een essentieel aspect van meercelligheid. Terwijl stabiele celinteracties gewoonlijk plaatsvinden tussen cellen van hetzelfde type, treden voorbijgaande celinteracties op tussen cellen van verschillende weefseltypen, zoals tussen neutrofielen en endotheelcellen. Selectinen zijn één klasse celadhesiemoleculen (CAM's) die koolhydraatliganden binden om tijdelijke celadhesie te vormen. Het zijn staafachtige eiwitten met een lang extracellulair deel van variabele lengte dat eindigt met het lectinedomein, een lectine van het C-type dat koolhydraten alleen bindt in de aanwezigheid van calciumionen. Er worden drie hoofdtypen selectinen geïdentificeerd op basis van hun weefselspecificiteit en lengte: L-selectinen, P-selectinen en E-selectinen.

Selectines in immuunrespons

De endotheelcellen die de bloedvaten bekleden, brengen P-selectines tot expressie en slaan deze op in de blaasjeslichamen die Weible-Palade-lichaampjes worden genoemd. Tijdens ontstekingen mobiliseert histaminestimulatie deze blaasjes snel naar het celoppervlak. Deze geactiveerde endotheelcellen verhogen ook hun E-selectine- en P-selectine-genen, waardoor ze worden voorbereid om vrij stromende leukocyten uit de bloedbaan te recruteren.

Leukocyten, zoals neutrofielen en eosinofielen, brengen de koolhydraatliganden, zoals PSGL-1, tot expressie op hun celoppervlak. De lange selectinen die uit de endotheelcellen steken, kunnen gemakkelijk een interactie aangaan met deze liganden en de vrij stromende leukocyten uit de bloedbaan "vangen". Selectinen bevinden zich aanvankelijk in de gesloten conformatie en binden daarom zwak aan hun liganden. Terwijl de leukocyt meestroomt, zorgt de schuifspanning van deze interacties er echter voor dat de selectines openen. Selectinen in open conformatie kunnen sterk aan hun liganden binden en zo de leukocyten helpen vertragen.

Selectines bij kanker

Metastatische kankercellen kapen het normale, door selectine gemedieerde rekruteringsproces om gezonde weefsels binnen te dringen. Deze metastatische cellen brengen de koolhydraatliganden tot expressie op hun celoppervlak en worden zo ontvankelijk om de endotheelcellen te binden. Na binding kunnen de kankercellen uit het bloedvat ontsnappen, via een proces dat extravasatie wordt genoemd. De kankercellen kunnen vervolgens de nieuwe locatie infiltreren en secundaire tumoren produceren.

Selecties

Cell adhesion is&#160; an essential aspect of multicellularity. While stable cell interactions usually occur between cells of the same type, transient ...

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Cell Biology

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Cell-Cell Interactions

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selectins in immune cell capture

Selectins help cells make short, temporary contacts during immune responses. They are cell adhesion molecules that bind carbohydrate ligands on other cells. These rod-like proteins have a long outside region and end in a lectin domain, which binds carbohydrates only when calcium ions are present.

Three main selectins are known: L-selectin, P-selectin, and E-selectin. Their names reflect where they are found and how long they are. This tissue specificity helps explain why selectins act in certain cell interactions instead of making permanent attachments.

In blood vessels, endothelial cells line the vessel wall and use selectins to recruit leukocytes during inflammation. These cells store P-selectin in vesicular bodies called Weibel-Palade bodies. When histamine stimulates the cells, the vesicles move quickly to the cell surface. The activated endothelial cells also increase E-selectin and P-selectin gene expression, which prepares them to attract free-flowing leukocytes.

Leukocytes such as neutrophils and eosinophils carry carbohydrate ligands on their surface, including PSGL-1. Long selectins on endothelial cells can reach out and catch these moving cells from the bloodstream. Selectins start in a closed form, so they bind weakly at first. As the leukocyte keeps moving, shear stress from the interaction opens the selectin. In the open form, the selectin binds more strongly and slows the leukocyte down.

Cancer cells can also use this same pathway. Metastatic cancer cells display carbohydrate ligands on their surface and can bind endothelial cells. This lets them leave the blood vessel by extravasation and enter a new tissue. Once there, they can grow into secondary tumors.

Selectins in Immune Cell Capture

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selectins

Selectins help cells make short, temporary contacts during immune responses. They are cell adhesion molecules that bind carbohydrate ligands on other cells. These rod-like proteins have a long outside region and end in a lectin domain, which binds carbohydrates only when calcium ions are present. Three main selectins are known: L-selectin, P-selectin, and E-selectin. Their names reflect where they are found and how long they are. This tissue specificity helps explain why selectins act in...

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key terms and concepts

Learn how selectins help leukocytes slow down, how inflammation activates endothelial cells, and how metastatic cancer cells use the same pathway.

Selectins in Immune Cell Capture | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

Selectins in Immune Cell Capture

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