Name: cell adhesion in tissues and infection
Uploaded: 2023-04-30T11:55:15.000Z
Duration: 1 min 24 s
Channel: JoVE

La unión adherente es una unión de anclaje que mantiene unidas las células en tejidos como el epitelio.
Las uniones adherentes son grandes complejos multiproteicos que comprenden tres clases principales de proteínas: las cadherinas adhesivas, el citoesqueleto de actina de anclaje y las cateninas enlazadoras.
El ensamblaje de la unión adherente comienza con la polimerización de los monómeros de actina cerca de la membrana celular para formar protuberancias llamadas lamelipodios.
Cuando los lamelípodos de las células vecinas están lo suficientemente cerca, las cadherinas de su superficie interactúan y desencadenan la localización de más cadherinas, formando grupos.
Estos grupos están estabilizados por cateninas beta, alfa y p120, que ayudan a reclutar más complejos de cadherina-catenina en el sitio de crecimiento.
A medida que la zona de contacto entre las dos células se expande, las alfa-cateninas cambian la polimerización de actina de ramificada a no ramificada, y las disponen paralelas a la membrana celular.
Estos filamentos de actina luego se asocian con la miosina para formar haces contráctiles, formando así una unión adherente madura.
La unión une el citoesqueleto de una célula con otra, mantenida unida a través de las interacciones extracelulares de las moléculas de cadherina.

<ol>
	<li>Niessen, Carien M. y Cara J. Gottardi. "Componentes moleculares de la unión adherente". Biochimica et Biophysica Acta (BBA)-Biomembranes 1778.3 (2008): 562-571.</li>
	<li>Baum, Buzz y Marios Georgiou. "Dinámica de las uniones adherentes en el establecimiento, mantenimiento y remodelación epitelial". Revista de Biología Celular 192.6 (2011): 907-917.</li>
	<li>Mengaud, Jérôme, et al. "La E-cadherina es el receptor de la internalina, una proteína de superficie necesaria para la entrada de L. monocytogenes en las células epiteliales". Celda 84.6 (1996): 923-932.</li>
</ol>

uniones adherentes

Adherens Junctions

Fuertes puntos de contacto entre células adyacentes las anclan entre sí, formando tejidos. Estas uniones de anclaje son de dos tipos: uniones adherentes y desmosomas. Las uniones adherentes son abundantes en tejidos como el epitelio y el endotelio, formando una zona continua de adhesión llamada cinturón de adhesión. En otros tejidos, como el músculo cardíaco, aparecen como grupos, uniendo las células para producir una contracción coordinada del músculo cardíaco.

Las uniones adherentes son dinámicas

Las células endoteliales que recubren los vasos sanguíneos están estrechamente unidas, formando una barrera que impide el escape de otras células y moléculas del torrente sanguíneo al tejido circundante. Sin embargo, durante una respuesta inmune, los leucocitos del torrente sanguíneo deben atravesar esta barrera y llegar al tejido diana. Las moléculas inflamatorias como las histaminas y las proteínas de señalización como el factor de crecimiento endotelial vascular (VGEF) desencadenan procesos posteriores, como la fosforilación y la internalización de cadherinas presentes en la superficie de las células endoteliales. Esto conduce al desmontaje de las uniones adherentes y aumenta la permeabilidad endotelial al crear espacios que permiten el paso de las células inmunitarias y otras moléculas. Por tanto, el mantenimiento y la ruptura de las uniones adherentes se regulan dinámicamente en respuesta a estímulos específicos.

Uniones adherentes e infección

Agentes infecciosos como Helicobacter pylori pueden ingresar al tejido del huésped al alterar las uniones adherentes y moverse a través de los espacios intercelulares. Estas bacterias producen proteasas que escinden el dominio extracelular de las cadherinas, provocando así el desmontaje de la unión. Las cadherinas de la superficie celular también son secuestradas como receptores por bacterias como Streptococcus pneumoniae para adherirse al epitelio de las vías respiratorias superiores.

Sin embargo, el secuestro más impresionante quizás lo demuestra la Listeria monocytogenes. Esta bacteria expresa proteínas de la pared celular que unen E-cadherinas y desencadenan el reclutamiento de ɑ, β y p120-cateninas en el sitio. Este reclutamiento inicia la polimerización dinámica de actina, formando protuberancias de membrana que envuelven a las bacterias en un proceso llamado fagocitosis inducida. De este modo, la bacteria logra entrar en una célula no fagocítica y prolifera dentro del huésped.

Uniones adherentes

Los fuertes puntos de contacto entre las células adyacentes las anclan entre sí, formando tejidos. Tales uniones de anclaje son de dos tipos: ...

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

cell adhesion in tissues and infection

Adherens junctions are strong cell-to-cell anchors that help tissues stay connected. These anchoring junctions work with desmosomes, another type of junction that holds adjacent cells together. In many epithelial and endothelial tissues, adherens junctions form a continuous adhesion belt. In heart muscle, they often appear as clusters that help cells work together for coordinated contraction.

Adherens junctions are also dynamic, especially in the cells that line blood vessels. These endothelial cells form a barrier that normally keeps cells and molecules inside the bloodstream. During an immune response, leukocytes, or white blood cells, must cross this barrier to reach damaged tissue. Inflammatory molecules such as histamines and signaling proteins such as vascular endothelial growth factor, or VEGF, can trigger phosphorylation and internalization of cadherins on the endothelial cell surface. Cadherins are adhesion proteins that help cells stick together. When this happens, adherens junctions break down, permeability increases, and gaps open for immune cells and other molecules to pass through.

Some infections also take advantage of adherens junctions. Helicobacter pylori can disrupt these junctions by producing proteases that cut the extracellular part of cadherins. This breaks the junctions and helps the bacteria move through the spaces between cells. Other bacteria, such as Streptococcus pneumoniae, use cadherins as receptors to attach to the upper respiratory epithelium. Listeria monocytogenes uses a more complex strategy. It binds E-cadherins and recruits alpha-, beta-, and p120-catenins, which starts actin polymerization. This creates membrane protrusions that engulf the bacteria in induced phagocytosis, allowing it to enter a nonphagocytic cell and multiply inside the host.

Cell Adhesion in Tissues and Infection

cell adhesion molecules - types and functions

cell-adhesion-molecules-types-and-functions

Cell Adhesion Molecules in Tissues

Cell adhesion molecules help cells stick together and work as part of a tissue. They give multicellular organisms physical strength and also help cells send signals across the plasma membrane. These proteins are important for coordinated activity in tissues and organ systems. CAMs are grouped into four main families: integrins, cadherins, selectins, and immunoglobulin-like CAMs, or IgCAMs. Each family supports cell interactions in a different way. Some CAMs help cells attach firmly, while...

structure of cadherins

Cadherins in Cell Junctions and Disease

Cadherins are cell adhesion proteins that help cells stick together and build tissues. Their name comes from their calcium-dependent binding. Early examples were named E-cadherin, P-cadherin, and N-cadherin after the epithelial, placental, and neuronal cells where they were first found. Classical cadherins share similar sequences and structures. Other cadherins, including those involved in cell signaling, are grouped as non-classical cadherins. This diversity comes from multiple cadherin genes...

cadherins in tissue organization

Cadherins Guide Cell Sorting in Tissues

Cadherins help cells sort into the right tissues during development. They are a large superfamily of cell adhesion molecules, with more than 180 variants. Different tissues express specific cadherin combinations, which helps cells recognize and stick to the right neighbors. Cadherins usually bind to the same or a closely related cadherin on another cell. This is called homophilic binding. Because of this matching behavior, cells of the same type tend to group together and form clusters that...

catenins

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...

selectins

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...

immunoglobulin-like cell adhesion molecules

immunoglobulin-like-cell-adhesion-molecules

Ig-CAMs in Neural Growth and Disease

Ig-CAMs, or immunoglobulin-like cell adhesion molecules, are cell surface glycoproteins in the immunoglobulin superfamily. They contain immunoglobulin domains, and some also have fibronectin type III domains. Their Ig domains can be glycosylated to different degrees. These molecules can bind to the same kind of Ig-CAM or to other ligands, such as integrins. Most Ig-CAMs help cells stick together only for a short time. The nectin class is different because it helps form stable junctions,...

overview of cell-cell junctions

Cell Junctions in Tissues

Cell junctions help hold tissues together and let neighboring cells communicate. In multicellular organisms, the three-dimensional shape of tissues depends on interactions between cells and the extracellular matrix. Cell-cell junctions are specialized structures made of multi-protein complexes on one cell that connect with similar complexes on another cell. These junctions are grouped into three main types based on function: occluding, anchoring, and gap junctions. Tight junctions, also called...

adherens junctions

Adherens junctions are strong cell-to-cell anchors that help tissues stay connected. These anchoring junctions work with desmosomes, another type of junction that holds adjacent cells together. In many epithelial and endothelial tissues, adherens junctions form a continuous adhesion belt. In heart muscle, they often appear as clusters that help cells work together for coordinated contraction. Adherens junctions are also dynamic, especially in the cells that line blood vessels. These...

tension response at adherens junctions

How Adherens Junctions Sense Force

Adherens junctions help cells stay attached while they respond to mechanical force. These multi-protein complexes can adapt to tensile force and shear stress. When the force changes, mechanosensory proteins in the junction can change shape. This process is called mechanotransduction. Alpha-catenin is one of the main force-sensing proteins in adherens junctions. It is an allosteric protein, which means its shape affects how it works. Alpha-catenin has three VH, or vinculin homology, domains...

desmosomes

Desmosomes and Cell Anchoring

Desmosomes are cell junctions that anchor cells together. They are button-like structures that create an interlinked network of intermediate filaments across cells. This strong link helps tissues resist mechanical stress and maintain tissue integrity. Desmosomes are built from multiple proteins. Their core includes desmosomal cadherins, which are adhesion proteins that bind to cadherins on neighboring cells. The two desmosomal cadherins are desmogleins and desmocollins. These transmembrane...

tight junctions

Tight Junction Proteins and Cell Barriers

Tight junction proteins form seals between neighboring cells. These molecular barriers help stop fluids, ions, and other small solutes from leaking across body cavities and tissue compartments in multicellular organisms. They are an important part of cell barriers in places where controlled movement matters. The main tight junction proteins are claudin and occludin. Other proteins include tricellulin and JAM, which stands for junctional adhesion molecule. Most of these proteins are 4-pass...

gap junctions

Cell Communication Through Gap Junctions

Gap junctions let adjacent animal cells share small molecules, ions, and secondary messengers. These communication channels connect the cytoplasm of neighboring cells. They are built from many molecular channels, often from a few hundred to thousands in one junction. Each channel is made of two halves called connexon hemichannels. A connexon is a hexamer, meaning it is formed by six transmembrane connexin proteins. The six proteins arrange in a ring and create a pore in the center. One...

key terms and concepts

Learn how adherens junctions hold tissues together, open during immune responses, and can be disrupted by bacteria like H. pylori, S. pneumoniae, and Listeria.

Cell Adhesion in Tissues and Infection | 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.

Cell Adhesion in Tissues and Infection

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