Name: cell adhesion molecules in tissues
Uploaded: 2023-04-30T11:55:46.000Z
Duration: 1 min 20 s
Channel: JoVE

אינטראקציות בין תאים הן נקודות מגע פיזיות בין תאים סמוכים. הם עוזרים להחזיק את התאים יחד ומאפשרים תקשורת טרנסממברנלית, חיונית לתפקוד מתואם של רקמות.
אינטראקציות תאים יציבות נמצאות ברקמות, כגון האנדותל, שם הן תומכות בארגון הרקמות. לעומת זאת, אינטראקציות חלשות וחולפות עוזרות לגייס תאים הנעים בחופשיות, כמו תאי מערכת החיסון.
אינטראקציות תאים אלה מתממשות באמצעות חלבונים מיוחדים על פני התא, הנקראים ביחד מולקולות היצמדות תאים או CAMs .
מבין ארבע המשפחות העיקריות של CAMs, משפחת האינטגרין מעורבת באינטראקציה של התא עם המטריצה החוץ תאית, בעוד ששלוש המשפחות האחרות מעורבות באינטראקציות תא-תא.
הראשונים הם הקאדרינים, אשר יוצרים אינטראקציות יציבות על ידי קשירת קאדרינים המבוטאים בתאים אחרים.
השני הם הסלקטינים. הם קושרים פחמימות ספציפיות על פני השטח של תאים אחרים ויוצרים אינטראקציות חולפות.
ולבסוף, החלבונים דמויי האימונוגלובולינים השייכים למשפחת האימונוגלובולינים יוצרים גם אינטראקציות חולפות על ידי קשירת חלבונים דומים אחרים ואינטגרינים על תאים אחרים.

<ol>
	<li>Harjunpää, Heidi, et al. "מולקולות הידבקות תאים ותפקידיהן וויסותן במיקרו-סביבה החיסונית והגידולית." גבולות באימונולוגיה (2019): 1078.</li>
</ol>

מולקולות הדבקה בתאים - סוגים ותפקודים

Cell Adhesion Molecules - Types and Functions

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מולקולות הדבקה של תאים (CAMs) הן מכריעות לרב-תאי ולתפקוד המתואם של רקמות ומערכות איברים. הן מאפשרות אינטראקציות פיזיות בין תאים ומספקות חוזק מכני לרקמות. הן גם מתפקדות כקולטנים להעברת אותות על פני ממברנת הפלזמה. ה-CAMs מסווגים באופן נרחב לארבע משפחות - אינטגרינים, קדהרינים, סלקטינים ו-CAMs דמויי אימונוגלובולינים (IgCAMs).

משפחות CAM

משפחת החלבונים של אינטגרין מעורבת בעיקר באינטראקציה של התא עם המטריקס הסובב אותו. עם זאת, אינטגרינים מסוימים יכולים לקשור CAMs על פני תא אחר ולהשתתף באינטראקציות ישירות בין תא לתא. לדוגמה, האינטגרינים על תאי מערכת החיסון קושרים IgCAMs המתבטאים על האנדותל של כלי הדם.

קדהרינים הם משפחת-על של גליקופרוטאינים תלויי סידן המעורבים בעיקר ביצירת הידבקויות חזקות של תאים. הם מרכיבים את צומת האדהרנס והדסמוזומים ברקמות, כגון האפיתל.

סלקטינים ו-IgCAMs מעורבים באינטראקציות חולפות בין תאים ומשתתפים בהפניית תאים לעבר אתרי יעד. לדוגמה, הם עוזרים בגיוס סלקטיבי של לימפוציטים לאיברי הלימפה המשניים.

CAM ורב-תאיות

CAMs נמצאים כמעט בכל האורגניזמים הרב-תאיים - מספוגים ונמטודות פשוטות ועד חסרי חוליות וחולייתנים מורכבים. המורכבות של האינטראקציות התאיות, ולכן של ה-CAMs, עולה עם מורכבות האורגניזמים. לדוגמה, בעוד שלזבוב הפירות D.melanogaster יש כ-500 גנים המעורבים בהיצמדות תאים, לחולייתנים מורכבים כמו יונקים יש למעלה מאלף גנים המקודדים לסוגים שונים של CAMs.
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מולקולות היצמדות תאים (CAMs) חיוניות לרב-תאיות ולתפקוד מתואם של רקמות ומערכות איברים. הם מאפשרים ...

cell-adhesion-molecules-types-and-functions

Education

JoVE Core

Cell Biology

ביולוגיה של התא

Unit 1

יחידה 1

Cell-Cell Interactions

אינטראקציות בין תאים

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

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 others help cells make short-lived contacts and move to the right place.

Integrins mainly help a cell interact with the surrounding matrix, which is the material around cells. Some integrins can also bind CAMs on another cell and take part in direct cell-cell contact. For example, integrins on immune cells bind IgCAMs on the vascular endothelium, the inner lining of blood vessels.

Cadherins are calcium-dependent glycoproteins. They are known for strong cell adhesion and help form adherens junctions and desmosomes in tissues such as epithelium. Selectins and IgCAMs usually support transient cell interactions. They also help guide cells to target sites, such as the selective recruitment of lymphocytes to secondary lymphoid organs.

CAMs are found in nearly all multicellular organisms, from sponges and simple nematodes to complex invertebrates and vertebrates. As organisms become more complex, their cell interactions and CAM systems also become more complex. For example, D. melanogaster has about 500 genes involved in cell adhesion, while mammals have over a thousand genes that code for different CAMs.

Cell Adhesion Molecules in Tissues

cell adhesion molecules - types and functions

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

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...

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 cell adhesion molecules help tissues stay strong, guide immune cells, and support cell signaling through four major CAM families.

Cell Adhesion Molecules in Tissues | 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.

Cell Adhesion Molecules in Tissues

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