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

カテニンは、細胞間接着に関与する多様なアダプタータンパク質のグループです。
カテニンは、カドヘリン、細胞骨格成分、およびさまざまな細胞骨格調節タンパク質に結合する複数の結合ドメインを持っています。したがって、彼らは細胞接着部位で細胞骨格をカドヘリンと結びつけます。
プラコグロビンやプラコフィリンなどの一部のカテニンは、カドヘリンと中間フィラメントとの間に安定した結合を確立するのに役立ちますが、α-カテニンやベータ-カテニンなどの他のカテニンは、原形質膜でアクチン細胞骨格を動的に組織化します。
アクチンフィラメントの組織化は、ベータカテニンがカドヘリン分子の細胞質ドメインに結合することから始まります。これに続いて、α-カテニンはβ-カテニンに結合します。
別のカテニンであるp120もこれらの複合体につながれ、膜上のカドヘリンの安定性を調節します。
いくつかのカドヘリン-カテニン複合体が集まると、α-カテニンは解離して細胞質二量体を形成します。
これらのα-カテニン二量体は、糸状アクチンと強く相互作用し、アクチン束の組織化を助けるため、細胞接着部位に細胞骨格強度を提供します。

<ol>
	<li>「カテニン:細胞がシグナルを交差させるのを防ぐ」 Developmental cell 11.5 (2006): 601-612.</li>
	<li>Moon, Randall T. "Wnt/β-catenin pathway." Science's STKE 2005.271 (2005): cm1-cm1.</li>
</ol>

カテニン

Catenins

カテニンは、複数の結合ドメインと、細胞結合複合体におけるリンカータンパク質として機能できる動的構造を特徴としています。 α-カテニンを除くすべてのカテニンは、アルマジロリピートと呼ばれる特徴的なタンパク質配列を含むため、アルマジロタンパク質とも呼ばれます。

細胞接合部のカテニン

カテニンはカドヘリンなどの細胞接着分子に結合し、細胞接合の種類に応じて異なる細胞骨格タンパク質に結合します。 接着結合部では、アクチン細胞骨格は、α、β、および p120 カテニンによって直接的または間接的に動的に組織化されます。 例えば、α-カテニンはF-アクチンに直接結合しますが、p120はRho GTPaseを介してアクチンの重合を調節します。 しかし、デスモソームでは、プラコグロビンおよびプラコフィリンと呼ばれる特別なカテニンと、デスモプラキンなどの他のタンパク質との相互作用によって中間フィラメントが組織化されます。

β-カテニンと細胞シグナル伝達

β-カテニンは、細胞接合部でカドヘリンに結合することに加えて、Wnt 経路などの細胞シグナル伝達でも機能します。 この経路では、フリズルドと呼ばれる細胞表面受容体への Wnt シグナル分子の結合が、細胞質内の β-カテニン濃度を増加させるカスケードを引き起こします。 これにより、β-カテニンが核に移行し、転写因子に結合し、標的遺伝子の発現を調節することが可能になります。 生物間で組織特異的な変異がいくつかある他のカテニンとは異なり、脊椎動物では β-カテニンの変異は 1 つだけ見つかります。 この変異体は、すべての脊椎動物種にわたって高度に保存されたアミノ酸配列で構成されています。

p120-カテニンとシナプス可塑性

カドヘリン - カテニン複合体は、記憶に関与するシナプス結合の強化と弱化であるシナプス可塑性の重要な部分です。 例えば、p120 はシナプス膜上のグルタミン酸受容体の安定化に関与しており、その結果、長期的な増強が維持されます。 また、神経カドヘリンのエンドサイトーシスを防止し、シナプス接合部でのカドヘリンのクラスター形成を促進することにより、神経カドヘリンの安定化にも関与しています。 p120 を下方調節すると、シナプス前ニューロンとシナプス後ニューロンの間の接着が防止されることが示されています。

カテニンは、複数の結合ドメインと動的構造によって特徴付けられ、細胞結合複合体のリンカータンパク質として機能することができます。...

Education

JoVE Core

Cell Biology

細胞生物学

Unit 1

ユニット1

Cell-Cell Interactions

細胞間相互作用

KEY TERMS AND CONCEPTS

主要用語と概念

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

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 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

Explore how catenins link cadherins to the cytoskeleton, support Wnt signaling, and help strengthen synapses in high school biology.

Catenins in Cell Junctions and Signaling | JoVE K12

cell biology

JoVE Core 細胞生物学は、複雑な細胞プロセスを、わかりやすく包括的なアニメーション ビデオ レッスンで説明します。このコレクションは、細胞小器官や膜、細胞輸送、細胞のエネルギー学など、細胞の必須コンポーネントと機能に焦点を当てています。これは、実際の研究実験における細胞生物学の応用を実証する科学者による実際のビデオによって補足されています。

Catenins in Cell Junctions and Signaling

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