Name: cell junctions in tissues
Uploaded: 2023-04-30T11:54:51.000Z
Duration: 1 min 14 s
Channel: JoVE

細胞結合は、細胞を細胞外マトリックスに結合して細胞-マトリックス結合を形成したり、組織内の隣接する細胞間の接触点として機能して細胞-細胞結合を形成することができる、大規模なマルチタンパク質複合体です。
通常、細胞には、タイトジャンクション、アンカリングジャンクション、ギャップジャンクションの3つの主要なタイプがあり、それぞれが異なる構造と機能を持っています。
円柱状上皮を考えてみましょう。これらの細胞の頂点付近のタイトジャンクションは、隣接する細胞膜を一緒に保持し、細胞間空間を通る分子の流れに対するバリアとして機能します。
この頂端部分の下には、接着ジャンクションとデスモソームの2種類のアンカージャンクションがあります。
これらの固定結合は、細胞間で相互接続された細胞骨格ネットワークを形成し、機械的な力に抵抗するのに役立ちます。
3番目のタイプであるギャップ結合は、原形質膜全体、特に基底端に向かって分散しています。これらの接合部は、隣接する細胞間のコミュニケーションチャネルとして機能し、分子とイオンが通過できるようにします。

<ol>
	<li>「タイトジャンクションと接着ジャンクションの間の相互作用」 実験的細胞研究 358.1 (2017): 39-44.</li>
	<li>「ギャップ結合とコネキシン相互作用タンパク質」 心臓血管研究 62.2 (2004): 233-245.</li>
</ol>

細胞間接合の概要

Overview of Cell-Cell Junctions

あらゆる多細胞生物における細胞の複雑な三次元配置は、細胞相互作用および細胞外マトリックスとの相互作用によって定義され、維持されます。 細胞間結合は、ある細胞上の複数タンパク質複合体が別の細胞上の複数タンパク質複合体と相互作用する特殊な構造です。 これらの細胞接合は、その機能に基づいて、閉塞結合、固定結合、およびギャップ結合の 3 つの主要なタイプに分類されます。

閉塞または密接な接合部

密着結合は主に、水や溶質などの分子が細胞間空間を通過するのを防ぐ機能があります。 これらは、隣接する膜上の同じタンパク質と直接相互作用する一連の膜貫通タンパク質として存在します。 したがって、それらは 2 つの細胞膜を互いに近接して保持し、分子の通過を防ぎます。 タイト結合は選択的に透過性を持ち、電荷特異的なイオンが通過できる一方で、他のイオンは遮断されます。

アンカー結合

固定接合部は細胞を一緒に保持し、組織構造に機械的強度を与えます。 それらは、カドヘリンと呼ばれる膜貫通接着分子を介して、ある細胞の細胞骨格が隣接する細胞の細胞骨格に固定される接触点を形成します。 アンカー結合部には 2 つのタイプがあります。

<ol style="list-style-type: circle;">
	<li>アクチン細胞骨格とアクチン細胞骨格を結びつける接着結合</li>
	<li>中間フィラメントを連結するデスモソーム</li>
</ol>

したがって、それらは組織の構造と機能を維持するために協力して機能する広範な細胞骨格ネットワークを形成します。

ギャップ結合

ギャップ結合は、細胞間のコミュニケーションを促進するタンパク質チャネルです。 要素である膜貫通タンパク質は、隣接する細胞の細胞質をつなぐチャネルを形成し、分子と電気インパルスの交換を可能にします。 分子の動きは、チャネルタンパク質の開閉によって調節されます。 たとえば、心臓のリズミカルな収縮の信号は、心筋組織のギャップ結合を介して細胞から細胞へと伝えられます。 しかし、植物細胞は細胞壁があるため、ギャップ結合を介して分子を交換することができません。 代わりに、原形質連絡と呼ばれるコミュニケーションチャネルを形成します。 これらは、ある細胞の細胞質が別の細胞の細胞質と連続するように、細胞壁を介して細胞を接続する膜で裏打ちされた細孔です。 したがって、原形質連絡によって接続された植物細胞間で溶質とイオンが自由に移動します。

あらゆる多細胞生物における細胞の複雑な三次元配置は、細胞同士の相互作用によって定義され、維持されます...

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

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 occluding junctions, stop water and solutes from moving through the spaces between cells. They do this with transmembrane proteins that match and bind to the same proteins on the adjacent cell membrane, keeping the two membranes close together. Tight junctions can also be selectively permeable, so some charge-specific ions can pass while others are blocked.

Anchoring junctions give tissues mechanical strength by holding cells together. They create contact points where the cytoskeleton of one cell attaches to the cytoskeleton of a neighboring cell through transmembrane adhesion molecules called cadherins. Two main forms are adherens junctions, which link actin filaments, and desmosomes, which link intermediate filaments. Together, these connections build a strong cytoskeletal network that supports tissue structure and function.

Gap junctions are channels that let cells communicate with each other. Their transmembrane proteins form a passage between the cytoplasms of adjacent cells, allowing molecules and electrical impulses to move across. The channels can open and close to control movement. In cardiac muscle, gap junctions help pass the signal for rhythmic heart contractions from cell to cell.

Plant cells do not use gap junctions because of the cell wall. Instead, they connect through plasmodesmata, which are membrane-lined pores that pass through the cell walls. These channels link the cytoplasm of one plant cell to another, allowing solutes and ions to move freely between them.

Cell Junctions in Tissues

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 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 tight junctions, anchoring junctions, and gap junctions help cells stay connected, strengthen tissues, and pass signals in animals and plants.

Cell Junctions in Tissues | 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。

Cell Junctions in Tissues

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