Name: catenins in cell junctions and signaling
Uploaded: 2023-04-30T11:55:07.000Z
Duration: 1 min 23 s
Channel: JoVE

Las cateninas son un grupo diverso de proteínas adaptadoras que participan en la adhesión célula-célula.
Las cateninas tienen múltiples dominios de unión que se unen a cadherinas, componentes del citoesqueleto y varias proteínas reguladoras del citoesqueleto. Por lo tanto, unen el citoesqueleto con cadherinas en los sitios de adhesión de las células.
Mientras que algunas cateninas, como la plakoglobina y la placofilina, ayudan a establecer conexiones estables entre las cadherinas y los filamentos intermedios, otras, como las alfa y beta-cateninas, organizan dinámicamente el citoesqueleto de actina en la membrana plasmática.
La organización de los filamentos de actina comienza con la unión de la beta-catenina al dominio citosólico de una molécula de cadherina. Después de esto, la alfa-catenina se une a la beta-catenina.
Otra catenina, la p120, también se une a estos complejos y regula la estabilidad de las cadherinas en la membrana.
A medida que algunos complejos de cadherina-catenina se agrupan, las alfa-cateninas se disocian y forman dímeros citosólicos.
Estos dímeros de alfa-catenina interactúan fuertemente con la actina filamentosa y ayudan a organizar los haces de actina, proporcionando así fuerza al citoesqueleto a los sitios de adhesión celular.

<ol>
	<li>Pérez-Moreno, Mirna y Elaine Fuchs. "Cateninas: evitar que las células reciban sus señales cruzadas". Célula de desarrollo 11.5 (2006): 601-612.</li>
	<li>Moon, Randall T. "Vía Wnt/β-catenina." Science's STKE 2005.271 (2005): cm1-cm1.</li>
</ol>

cateninas

Catenins

Las cateninas se caracterizan por múltiples dominios de unión y estructuras dinámicas que les permiten funcionar como proteínas conectoras en complejos de unión celular. Todas las cateninas, excepto la α-catenina, contienen una secuencia proteica característica llamada repetición de armadillo y, por lo tanto, también se denominan proteínas de armadillo.

Cateninas en las uniones celulares

Las cateninas se unen a moléculas de adhesión celular como las cadherinas y las unen a diferentes proteínas del citoesqueleto según el tipo de unión celular. En la unión adherente, el citoesqueleto de actina está organizado dinámicamente por las cateninas alfa, beta y p120, tanto directa como indirectamente. Por ejemplo, la α-catenina se une directamente a la actina F, mientras que p120 regula la polimerización de actina a través de Rho GTPasas. Sin embargo, en los desmosomas, los filamentos intermedios se organizan mediante interacciones de cateninas especiales llamadas placoglobina y placofilina con otras proteínas como la desmoplaquina.

β-catenina y señalización celular

Además de unirse a cadherinas en las uniones celulares, la β-catenina también puede funcionar en la señalización celular, como la vía Wnt. En esta vía, la unión de una molécula señal Wnt al receptor de la superficie celular, denominada frizzled, desencadena una cascada que aumenta la concentración de β-catenina en el citoplasma. Esto permite que la β-catenina se transloque al núcleo, se una a factores de transcripción y regule la expresión del gen diana. A diferencia de otras cateninas que tienen varias variantes específicas de tejido en todos los organismos, en los vertebrados solo se encuentra una única variante de β-catenina. Esta variante está compuesta por una secuencia de aminoácidos altamente conservada en todas las especies de vertebrados.

p120-catenina y plasticidad sináptica

Los complejos cadherina-catenina son una parte importante de la plasticidad sináptica: el fortalecimiento y debilitamiento de las conexiones sinápticas implicadas en la memoria. Por ejemplo, p120 participa en la estabilización de los receptores de glutamato en la membrana sináptica, manteniendo así la potenciación a largo plazo. También participa en la estabilización de las cadherinas neurales al prevenir su endocitosis y promover la agrupación de cadherinas en las uniones sinápticas. Se ha demostrado que la regulación negativa de p120 previene la adhesión entre las neuronas pre y postsinápticas.

Cateninas

Las cateninas se caracterizan por múltiples dominios de unión y estructuras dinámicas que les permiten funcionar como proteínas enlazadoras en complejos de unión celular. ...

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

catenins in cell junctions and signaling

Catenins help cells stay connected and also support signaling inside the body. These proteins act as linker proteins in cell junction complexes because they have multiple binding domains and flexible structures. Most catenins contain a protein sequence called the armadillo repeat, so they are also known as armadillo proteins. Alpha-catenin is the main exception.

Catenins bind to cell adhesion molecules such as cadherins. They then connect cadherins to cytoskeletal proteins, and the exact link depends on the type of cell junction. At adherens junctions, alpha-catenin, beta-catenin, and p120-catenin help organize the actin cytoskeleton. Alpha-catenin binds directly to F-actin. p120 helps control actin polymerization through Rho GTPases.

At desmosomes, catenins help organize intermediate filaments instead of actin. In this case, special catenins called plakoglobin and plakophilin interact with other proteins such as desmoplakin. These interactions help build strong cell connections in tissues that need mechanical support.

Beta-catenin also has a signaling role in the Wnt pathway. When a Wnt signal molecule binds to the frizzled receptor on the cell surface, a cascade raises beta-catenin levels in the cytoplasm. Beta-catenin can then move into the nucleus, bind to transcription factors, and regulate target gene expression. In vertebrates, only one beta-catenin variant is found, and its amino acid sequence is highly conserved across species.

p120-catenin also plays an important role in synaptic plasticity, which is the strengthening and weakening of synaptic connections involved in memory. It helps stabilize glutamate receptors on the synaptic membrane and supports long-term potentiation. p120 also stabilizes neural cadherins by preventing their endocytosis and by promoting cadherin clustering at synaptic junctions. When p120 is downregulated, adhesion between pre- and postsynaptic neurons is reduced.

Catenins in Cell Junctions and Signaling

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catenins

Catenins help cells stay connected and also support signaling inside the body. These proteins act as linker proteins in cell junction complexes because they have multiple binding domains and flexible structures. Most catenins contain a protein sequence called the armadillo repeat, so they are also known as armadillo proteins. Alpha-catenin is the main exception. Catenins bind to cell adhesion molecules such as cadherins. They then connect cadherins to cytoskeletal proteins, and the exact link...

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immunoglobulin-like-cell-adhesion-molecules

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overview of cell-cell junctions

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adherens junctions

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key terms and concepts

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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.

Catenins in Cell Junctions and Signaling

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