Name: how the extracellular matrix shapes tissues
Uploaded: 2025-05-22T09:05:46.000Z
Duration: 1 min 29 s
Channel: JoVE

The extracellular matrix, or ECM, is an interconnected network composed of fibers and ground substance, which is mostly interstitial fluid that fills the space between the cells, connective tissue fibers, and capillaries.
The molecular makeup of each microenvironment is secreted by local cells, ranging from fibroblasts to macrophages, resulting in differences in the exact composition and physical properties.
For instance, matrices are filled with polymerized glycosaminoglycans or GAGs for short. They bind water and other proteins, forming proteoglycans. The most common, chondroitin sulfates, are vital to cartilage and bones, and their gradual loss leads to osteoarthritis.
Another protein called elastin contributes to stretchiness, allowing muscles and skin to be flexible, whereas rigidity is provided by long, thick, fibrous glycoproteins called collagens. While ubiquitous, they&#39;re especially important to strong and extremely tough tissues like tendons, which join muscles to bones.
The glue is fibronectin, a cell adhesion protein that allows cells to attach to the different matrix elements, including collagen, GAGs, and integrins, membrane proteins that connect cells to the environm

the extracellular matrix

The Extracellular Matrix

<h4>Overview</h4>
In order to maintain tissue organization, many animal cells are surrounded by structural molecules that make up the extracellular matrix (ECM). Together, the molecules in the ECM maintain the structural integrity of tissue as well as the remarkable specific properties of certain tissues.
<h4>Composition of the Extracellular Matrix</h4>
The extracellular matrix (ECM) is commonly composed of ground substance, a gel-like fluid, fibrous components, and many structurally and functionally diverse molecules. These molecules include polysaccharides called glycosaminoglycans (GAGs). GAGs occupy most of the extracellular space and often take up a large volume relative to their mass. This results in a matrix that can withstand tremendous forces of compression. Most GAGs are linked to proteins&#8212;creating proteoglycans. These molecules retain sodium ions based on their positive charge and therefore attract water, which keeps the ECM hydrated.
The ECM also contains rigid fibers such as collagens&#8212;the primary protein component of the ECM. Collagens are the most abundant proteins in animals, making up 25% of protein by mass. A large diversity of collagens with structural similarities provide tensile strength to many tissues.
Notably, tissue like skin, blood vessels, and lungs need to be both strong and stretchy to perform their physiological role. A protein called elastin gives particular fibers the ability to stretch and retract. Fibronectin is a glycoprotein important in cell adhesion, as it directly attaches to proteins that span the membrane of cells, specifically integrins, linking the membrane to the ECM. Integrin also interacts with collagen, which may elicit intracellular responses.
<h4>Extracellular Matrix Composition Is Tissue- and Cell-type Dependent</h4>
The makeup and relative proportion of each of these molecules are determined by the location, physiological function, and neighboring cell types of the tissue in which the cells reside. This specific molecular makeup of the ECM is referred to as the local microenvironment. Cells in a particular tissue secrete molecules that determine the surrounding ECM. For example, intestinal cells synthesize, modify, and secrete the molecules necessary for the matrix that surrounds them, while osteoblasts generate the molecules of the rigid ECM of human bone. This diversity in ECM composition in different tissues creates particular properties according to their unique role and function.
<h4>Extracellular Matrix Can Be Involved in Cell Communication</h4>
The interaction between cells and the local ECM has been shown to have an intracellular impact as well. For example, forces on transmembrane integrin molecules can result in activation of the intracellular actomyosin network. This may promote cell migration, division, and other cellular responses. Some of these responses include changes in gene expression and cell signaling cascades. Likewise, integrin can communicate intracellular information to the outside of the cell. Additionally, ECM is known to bind signaling molecules, which can be released upon ECM degradation.
<h4>Remodeling of the Extracellular Matrix</h4>
Animal cells need to have the capacity to degrade and remodel the ECM. This is particularly true in cases of tissue repair and growth. Consequently, cells typically possess the enzymes necessary to break down the ECM. These enzymes include matrix metalloproteases (MMPs) which work with other enzymes to degrade proteins such as collagen and fibronectin. ECM degradation and remodeling are important in healthy tissue growth, including blood vessel branching. On the downside, ECM remodeling also contributes to the metastasis of cancerous cells as they spread through the body.

Overview
In order to maintain tissue organization, many animal cells are surrounded by structural molecules that make up the extracellular matrix (ECM). ...

Education

JoVE Core

Cell Biology

Unit 1

Extracellular Matrix in Animals

KEY TERMS AND CONCEPTS

how the extracellular matrix shapes tissues

The extracellular matrix, or ECM, helps animal tissues stay organized and keeps cells in the right place. It is made of structural molecules that support tissue shape and give certain tissues their special properties.

The ECM usually contains a gel-like ground substance, fibrous parts, and many molecules with different jobs. One major group is glycosaminoglycans, or GAGs, which are polysaccharides. GAGs fill much of the space outside cells and can take up a large volume compared with their mass, so the matrix can resist compression. Many GAGs are attached to proteins and form proteoglycans. These molecules hold sodium ions, attract water, and help keep the ECM hydrated.

The ECM also includes rigid fibers such as collagens, which are the main protein component of the ECM. Collagens are the most abundant proteins in animals and make up about 25% of protein by mass. Their many related forms give tissues tensile strength, or resistance to pulling forces. Elastin is another important protein. It allows fibers to stretch and then recoil, which is useful in tissues such as skin, blood vessels, and lungs.

Fibronectin is a glycoprotein that helps cells stick to the ECM. It binds to integrins, which are proteins that span the cell membrane and connect the membrane to the ECM. Integrin can also interact with collagen, and these contacts may trigger responses inside the cell.

The exact mix of ECM molecules depends on the tissue, its function, and the cells around it. This local molecular setting is called the microenvironment. Cells in each tissue help make their own ECM. Intestinal cells produce and secrete the molecules around them, while osteoblasts build the rigid ECM of bone. These differences give each tissue the properties it needs.

The ECM also plays a role in cell communication. When force acts on integrins, it can activate the actomyosin network inside the cell. This may affect cell movement, cell division, gene expression, and signaling pathways. Integrins can also send information outward from the cell. In addition, the ECM can store signaling molecules and release them when it is broken down.

Animal cells must also be able to degrade and remodel the ECM. This is important during tissue growth and repair. Cells use enzymes such as matrix metalloproteases, or MMPs, to break down ECM proteins like collagen and fibronectin. ECM remodeling helps healthy processes such as blood vessel branching. It can also support cancer cell metastasis, which is when cancer cells spread through the body.

How the Extracellular Matrix Shapes Tissues

how-the-extracellular-matrix-shapes-tissues

The extracellular matrix, or ECM, helps animal tissues stay organized and keeps cells in the right place. It is made of structural molecules that support tissue shape and give certain tissues their special properties. The ECM usually contains a gel-like ground substance, fibrous parts, and many molecules with different jobs. One major group is glycosaminoglycans, or GAGs, which are polysaccharides. GAGs fill much of the space outside cells and can take up a large volume compared with their...

glycosaminoglycans

GAGs in Tissue Support and Lubrication

Glycosaminoglycans, or GAGs, are long, linear polymers that help build and protect animal tissues. They are also called mucopolysaccharides. Their repeating units are made of an amino sugar, such as N-acetylglucosamine or N-acetylgalactosamine, plus a uronic acid, usually glucuronic acid or iduronic acid. GAGs are found in the extracellular matrix of vertebrates, invertebrates, and bacteria. Their polar nature lets them attract water. This makes them useful as lubricants and as shock absorbers...

collagens are the major structural proteins of ecm

collagens-are-the-major-structural-proteins-of-ecm

Collagen Fibers Give Tissues Strength

Collagen fibers give connective tissues strength and help them resist stretching. They are one of three main fiber types secreted by fibroblasts, along with elastic fibers and reticular fibers. Collagen fibers are made from fibrous protein subunits linked into long, straight fibers. These fibers are flexible, but they also have great tensile strength. Tensile strength is the ability to resist pulling forces. Collagen fibers help ligaments and tendons stay resilient and strong. They also hold...

fibril-associated collagen

FACIT Collagens in the Extracellular Matrix

FACIT collagens are fibril-associated collagens found in the extracellular matrix. FACIT stands for fibril-associated collagens with interrupted triple helices. These collagens help connect collagen fibrils to each other and to other extracellular matrix proteins. Type II collagen fibrils in cartilage provide a clear example. They have covalently bound type IX fibril-associated collagens at regular intervals. Other FACIT collagens include types XII, XIV, XVI, XIX, XX, XXI, and XXII. These...

elastin is responsible for tissue elasticity

elastin-is-responsible-for-tissue-elasticity

Elastic Tissues in Skin, Vessels, and Ears

Elastic tissues contain elastin, a protein mixed with smaller amounts of other proteins and glycoproteins. Elastin helps tissue return to its original shape after it is stretched or compressed. This property is important in body parts that must bend, stretch, and recoil. Elastic fibers are found in elastic tissues in the skin and in the elastic ligaments of the vertebral column. Ligaments and tendons are both made of dense regular connective tissue, but ligaments do not always have all of...

fibronectins connect cells with ecm

Fibronectin and Cell Attachment in ECM

Fibronectin is an adhesive glycoprotein in the extracellular matrix of embryogenic and adult tissue. It helps regulate cell motility and attachment. In many tissues, fibronectin gives cells a place to bind and move along. A fibronectin molecule is made of two identical polypeptide chains. These chains are joined at the C-terminal by a pair of disulfide bonds. Fibronectin also binds proteoglycans and collagen. It then links to integrin proteins, which interact with transmembrane proteins in the...

matrix proteoglycans and glycoproteins

Extracellular Matrix Support Proteins

Proteoglycans and matrix glycoproteins help build the extracellular matrix. The extracellular matrix is the material outside cells that gives tissues support and structure. Proteoglycans are heavily glycosylated proteins, and they are commonly found woven through collagen fibers. Hyaline cartilage shows how proteoglycans work. This is the most common type of cartilage in the body. It contains short, scattered collagen fibers with large amounts of proteoglycans. The proteoglycans carry long...

role of matrix metalloproteases in degradation of ecm

role-of-matrix-metalloproteases-in-degradation-of-ecm

How MMPs Remodel the Extracellular Matrix

Matrix metalloproteases (MMPs) are enzymes that break down proteins and glycoproteins in the extracellular matrix, or ECM. The ECM is the dense network around cells. By cutting ECM molecules, MMPs help cells move and grow through tissue. MMPs are important during embryonic development and morphogenesis, the process that shapes body form. A classic example comes from a tadpole’s tail during metamorphosis. The first MMP activity discovered was a collagenase, an enzyme that cuts collagen. This...

basal lamina are the specialized form of ecm

basal-lamina-are-the-specialized-form-of-ecm

Basal Lamina Structure and Cell Attachment

The basal lamina is a thin extracellular layer that sits beneath cells and separates them from other tissues. It acts as a support layer for epithelium and helps anchor it to the tissue below. Its structure includes three layers: lamina lucida, lamina densa, and lamina reticularis. The basal lamina is made of glycoproteins and collagen. Key proteins in this framework include laminins, perlecan, entactin, and type IV collagen. Cell membrane proteins such as integrins and dystroglycan bind to...

laminins are the adhesive proteins of basal lamina

laminins-are-the-adhesive-proteins-of-basal-lamina

Laminin Structure and Basal Lamina Support

Laminins are large extracellular matrix proteins that help build the basal lamina. Each laminin molecule has three chains: alpha, beta, and gamma. These chains are encoded by five alpha genes, four beta genes, and three gamma genes. In humans, the alpha chains are LAMA1, LAMA2, LAMA3, LAMA4, and LAMA5. The beta chains are LAMB1, LAMB2, LAMB3, and LAMB4. The gamma chains are LAMC1, LAMC2, and LAMC3. Laminin types are named based on which three chains they contain. Laminins join with one...

type iv collagen of basal lamina

Type IV Collagen in Basement Membranes

Type IV collagen is a network-forming collagen found in basement membranes. It acts as a barrier between epithelial and endothelial cells. It also helps form the backbone of the basement membrane with laminin, entactin, proteoglycans, and fibronectin. Beyond support, type IV collagen also helps with signaling functions linked to normal body processes and disease. A type IV collagen molecule contains six alpha chains. These chains can form at least three heterotrimeric triple-helical...

key terms and concepts

Explore how the extracellular matrix supports tissue structure, cell adhesion, hydration, signaling, and remodeling in animal cells and tissues.

How the Extracellular Matrix Shapes Tissues | JoVE K12

cell biology

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How the Extracellular Matrix Shapes Tissues

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