Name: myosin drives cell adhesion and polarity
Uploaded: 2023-04-30T10:17:24.000Z
Duration: 1 min 18 s
Channel: JoVE

Cells migrate by extending membrane protrusions at the leading edge of the cell and retracting the membrane at the trailing edge of the cell, thus, pushing the cell forward.
These protrusion and retraction forces are generated mainly by the motor protein myosin-II.
Its globular head regions bind filamentous actin and use energy from ATP hydrolysis to pull and contract the actin bundles.
For example, at the lamellipodial front, a type of membrane protrusion, the myosin contracts the actin filaments anchored to cell-matrix junctions.
This increased mechanical stress strengthens the junction, thus forming mature focal adhesions.
These anchorage points produce traction forces on the substratum, pushing the cell forward.
At the rear end of lamellipodia, the bipolar myosin binds actin and bridges the branched filaments.
Then, the myosin heads pull the actin filaments and reorient them parallel to the lamellipodial front, retracting the sides of the cell.
This retraction directs the rear of the cell to follow the lamellipodial front, resulting in directed cell migration.

role of myosin in cell migration

Role of Myosin in Cell Migration

Myosins are multimeric motor proteins involved in various cellular processes such as migration, adhesion, and proliferation. Myosin II is the most common type in animal cells, which binds and cross-links actin filaments.
Myosin II&#160; is a hexamer comprising two heavy chains with globular heads and coiled-coil tails, two regulatory light chains, and two essential light chains. The ATPase sites on the myosin heads hydrolyze ATP, and the released phosphate generates the force for contraction. It is this myosin-driven contraction of actin filaments and actin bundles that directs cell migration.
Myosin Promotes Adhesion
During cell migration, the lamellipodium at the cell front develops new focal adhesions that produce traction forces on the substratum. Studies have demonstrated that myosin is essential for the maturation of these adhesions, though the exact mechanism is not well understood. One hypothesis is that the myosin contractile force changes the conformation of cytoskeletal linker proteins, such as talin. This change exposes cryptic binding sites to actin and other linker proteins, thereby strengthening the adhesion. A second hypothesis states that adhesion proteins, such as integrins bound to actin, are clustered by the myosin-driven bundling of actin filaments. Thus, myosin-driven clustering of adhesion molecules, and changes in linker proteins, aid in the maturation of focal adhesions during cell migration.
Myosin and Organelle Positioning
Directional cell migration requires the establishment of cell polarity to determine the cell front and rear. In response to external stimuli, intracellular signaling cascades target various proteins, including myosin, to establish this polarity. Myosin is essential for repositioning the organelles, including the nucleus, Golgi apparatus, and the centrosomes, in alignment with the cell&#39;s polarity. For example, myosin anchors actin filaments around the nucleus by interacting with the linker protein nesprin embedded in the nuclear membrane. Thus, myosin helps to reposition the nucleus within the actin network as the cell changes shape during migration.

Myosins are multimeric motor proteins involved in various cellular processes such as migration, adhesion, and proliferation. Myosin II is the most common ...

Education

JoVE Core

Cell Biology

Unit 1

Cell Polarization and Migration

KEY TERMS AND CONCEPTS

myosin drives cell adhesion and polarity

Myosin is a motor protein that helps cells migrate by building force, strengthening attachments, and setting cell polarity. In animal cells, myosin II is the most common type. It binds and cross-links actin filaments, the protein fibers that help a cell move and change shape.

Myosin II is a hexamer, or six-part complex. It has two heavy chains with globular heads and coiled-coil tails, plus two regulatory light chains and two essential light chains. The ATPase sites on the myosin heads break down ATP, and the released phosphate helps generate the force for contraction. This myosin-driven contraction of actin filaments and actin bundles guides cell migration.

Myosin also helps cells form stronger focal adhesions at the front of the moving cell. These new adhesions form in the lamellipodium, the broad leading edge of the cell, and they create traction on the surface below. Studies show that myosin is needed for these adhesions to mature, although the exact mechanism is not fully known. One idea is that myosin force changes linker proteins such as talin and exposes hidden binding sites. Another idea is that myosin bundles actin filaments and clusters adhesion proteins such as integrins. Both processes can support focal adhesion maturation during migration.

Directional cell migration also depends on cell polarity, which sets the front and rear of the cell. External signals trigger intracellular pathways that target proteins, including myosin, to establish this polarity. Myosin helps move organelles such as the nucleus, Golgi apparatus, and centrosomes into the right position. For example, myosin anchors actin filaments around the nucleus by working with the linker protein nesprin in the nuclear membrane, helping reposition the nucleus as the cell changes shape.

Myosin Drives Cell Adhesion and Polarity

cell migration

Cell Migration in Wound Healing and Cancer

Cell migration is the movement of cells from one place to another. It is important in embryological development, repair and regeneration, immune response, and metastasis. Cells respond to chemical signals or mechanical signals from specific organs or tissues. The movement process has three main steps: polarization, protrusion, and release. During polarization, the cell forms a clear front and rear, which sets the direction of movement. Then the front protrudes, forms new adhesions, and creates...

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Cell Surface Protrusions in Movement

Cell surface protrusions help cells move, absorb nutrients, and respond to their surroundings. These extensions form when the cytoskeleton, the cell’s internal support system, rearranges. The most commonly seen protrusions include lamellipodia, pseudopodia, filopodia, microvilli, invadopodia, and podosomes. These protrusions are often grouped as static or dynamic. Microvilli are stable, finger-like projections with a generally stable actin architecture. They are brush-like extensions on the...

mechanism of lamellipodia formation

How Cells Push Forward with Lamellipodia

Cells move forward by building lamellipodia, which are thin membrane protrusions at the leading edge. These structures are supported by a mesh of actin filaments that may be linked, branched, or unbranched. Actin works with myosin motor proteins to form the actomyosin complex in the cytoskeleton, and this complex can generate contractile stress. That contractility helps cells sense the stiffness of the extracellular matrix, or ECM, and apply force during migration. Lamellipodia begin to form...

mechanism of filopodia formation

Filopodia in Cell Movement and Contact

Filopodia are thin, actin-rich cell protrusions that help cells move and make contact. They appear in different cell types in different places and lengths. That variation suggests they can support several cell functions. In many cases, filopodia guide migrating cells during normal tissue morphogenesis and cancer metastasis. They help cells recognize the extracellular matrix and make their first contact with it. Filopodia can also act as stationary anchors or help two cells communicate. A...

cancer cell migration through invadopodia

cancer-cell-migration-through-invadopodia

How Invadopodia Help Cancer Cells Spread

Invadopodia are cell surface structures that help cancer cells break down the extracellular matrix, or ECM. The ECM is the material outside cells that gives tissues support. Invadopodia are part of a larger group called invadosomes, which also includes structures found in normal cells such as macrophages, endothelial cells, and neurons. Macrophage podosomes and tumor cell invadopodia are both invadosomes, but they are not the same. Podosomes are short-lived and last only a few minutes.

cell motility through blebbing

Blebbing in Cell Movement and Cell Death

Blebbing is a membrane change seen in cell movement and cell death. A bleb is a membrane protrusion that forms when pressure from the cytoplasm pushes the plasma membrane outward. Blebs can appear in fibroblasts, immune cells, and single-celled organisms such as amoebas. Blebs help cells move through tight spaces in the extracellular matrix, or ECM. In multicellular organisms, migrating cells must squeeze between other cells and through this three-dimensional matrix. Actin-driven protrusions...

Myosin is a motor protein that helps cells migrate by building force, strengthening attachments, and setting cell polarity. In animal cells, myosin II is the most common type. It binds and cross-links actin filaments, the protein fibers that help a cell move and change shape. Myosin II is a hexamer, or six-part complex. It has two heavy chains with globular heads and coiled-coil tails, plus two regulatory light chains and two essential light chains. The ATPase sites on the myosin heads break...

cell polarization by rho proteins

Rho Proteins in Cell Front and Rear

Cell polarity gives a cell two different sides. This uneven layout is important for embryogenesis, axon migration, glucose transport across epithelial cells, and directional cell migration. In migrating cells, signals from inside or outside the cell trigger pathways that reorganize the actin cytoskeleton and build this polarity. The Rho family proteins Cdc42, Rac, and Rho help control that process. These proteins are small GTPases, which means they act like molecular switches and can shift...

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chemotaxis-and-direction-of-cell-migration

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cytoskeletal coordination in cell migration

cytoskeletal-coordination-in-cell-migration

Cell Polarity During Migration

Cell polarity during migration depends on the cytoskeleton. As a cell moves, it changes shape through repeated attachment to and detachment from the substratum, the surface it grows or moves on. The cell also shifts its organelles to match these changes. This movement is controlled by a dynamic cytoskeletal network. The network includes actin filaments, intermediate filaments, and microtubules. These parts do not work alone. They communicate through cytoskeletal crosstalk, which means direct...

key terms and concepts

Learn how myosin powers actin contraction, strengthens focal adhesions, and helps position the nucleus and other organelles during cell migration.

Myosin Drives Cell Adhesion and Polarity | 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.

Myosin Drives Cell Adhesion and Polarity

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