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

Las selectinas son glicoproteínas de la superficie celular que se unen a los ligandos de carbohidratos y participan en la adhesión transitoria célula-célula.
Todas las selectinas comprenden un dominio de lectina N-terminal y un factor de crecimiento epidérmico o dominio EGF que regulan la especificidad y la fuerza de unión.
Sin embargo, el número de repeticiones conservadas de secuencia o dominios SCR puede variar de dos a nueve repeticiones dependiendo del tipo de selectina.
Las L-selectinas cortas expresadas en las células inmunitarias como los linfocitos les ayudan a migrar a los ganglios linfáticos mediante la unión de ligandos en las células endoteliales.
Las P selectinas más grandes se expresan principalmente en las plaquetas. Ayudan a agregar plaquetas y células inmunitarias en el sitio de la lesión.
Un tercer tipo, llamado E-selectinas, se expresa temporalmente junto con las P-selectinas en las células endoteliales durante una respuesta inmunitaria.
Estas selectinas forman interacciones débiles y transitorias con los leucocitos que fluyen libremente y los ralentizan.
Luego, los leucocitos ruedan a lo largo de la superficie endotelial, donde otras moléculas de adhesión celular ayudan a reclutarlos a los microambientes tisulares apropiados, un proceso llamado localización de leucocitos.

<ol>
	<li>Borsig, Lubor. "Selectinas en la inmunidad contra el cáncer". Glycobiology 28.9 (2018): 648-655.</li>
	<li>Gout, Stéphanie, Pierre-Luc Tremblay y Jacques Huot. "Selectinas y ligandos de selectina en la extravasación de células cancerosas y selectividad de órganos de metástasis". Metástasis clínica y experimental 25.4 (2008): 335-344.</li>
</ol>

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Selectins

La adhesión celular es un aspecto esencial de la multicelularidad. Si bien las interacciones celulares estables generalmente ocurren entre células del mismo tipo, las interacciones celulares transitorias ocurren entre células de diferentes tipos de tejidos, como entre neutrófilos y células endoteliales. Las selectinas son una clase de moléculas de adhesión celular (CAM) que se unen a ligandos de carbohidratos para formar una adhesión celular transitoria. Son proteínas en forma de bastones con una parte extracelular larga de longitud variable que termina en el dominio de lectina, que es una lectina de tipo C que se une a los carbohidratos solo en presencia de iones de calcio. Se identifican tres tipos principales de selectinas en función de su especificidad y longitud del tejido: selectinas L, selectinas P y selectinas E.

Selectinas en la respuesta inmune

Las células endoteliales que recubren los vasos sanguíneos expresan selectinas P y las almacenan en cuerpos vesiculares llamados cuerpos de Weible-Palade. Durante la inflamación, la estimulación con histamina moviliza rápidamente estas vesículas hacia la superficie celular. Estas células endoteliales activadas también regulan positivamente sus genes de selectina E y selectina P, preparándolas así para reclutar leucocitos de flujo libre en el torrente sanguíneo.

Los leucocitos, como los neutrófilos y los eosinófilos, expresan ligandos de carbohidratos, como el PSGL-1, en su superficie celular. Las selectinas largas que sobresalen de las células endoteliales pueden interactuar fácilmente con estos ligandos y "atrapar" los leucocitos que fluyen libremente del torrente sanguíneo. Las selectinas inicialmente tienen una conformación cerrada y, por lo tanto, se unen débilmente a sus ligandos. Sin embargo, a medida que el leucocito fluye, la tensión de corte de estas interacciones hace que se abran las selectinas. Las selectinas en conformación abierta pueden unirse fuertemente a sus ligandos y así ayudar a ralentizar los leucocitos.

Selectinas en el cáncer

Las células cancerosas metastásicas secuestran el proceso de reclutamiento normal mediado por selectina para invadir tejidos sanos. Estas células metastásicas expresan los ligandos de carbohidratos en su superficie celular y, por lo tanto, se vuelven receptivas para unirse a las células endoteliales. Al unirse, las células cancerosas pueden escapar del vaso sanguíneo, mediante un proceso llamado extravasación. entonces, las células cancerosas pueden infiltrarse en el nuevo sitio y producir tumores secundarios.

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La adhesión celular es un aspecto esencial de la multicelularidad. Mientras que las interacciones celulares estables suelen ocurrir entre células del mismo tipo, las ...

Education

Educación

JoVE Core

Cell Biology

Biología Celular

Unit 1

Unidad 1

Cell-Cell Interactions

Interacciones célula-célula

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

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 Biología Celular ilustra procesos celulares complejos mediante completos vídeos animados fáciles de entender. Esta colección se centra en los componentes esenciales de las células y su funcionamiento, incluyendo los orgánulos y las membranas, el transporte celular y el metabolismo energético celular. Todo este material se complementa con los vídeos de científicos en acción, que muestran la aplicación de la biología celular en experimentos reales de investigación.

Selectins in Immune Cell Capture

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