Name: filopodia in cell movement and contact
Uploaded: 2023-04-30T10:16:54.000Z
Duration: 1 min 39 s
Channel: JoVE

Filopodia formation requires actin cytoskeleton reorganization at the cell&#39;s leading edge into thin parallel bundles by IRSp53.
IRSp53, a multi-domain protein, impacts the actin cytoskeleton and the membrane.
When a cell receives an appropriate signal, Cdc42&#8212; a small Rho family protein, switches to its GTP-bound active state.&#160;
The GTP-bound Cdc42 recruits IRSp53 dimers to the cell membrane, forming activated Cdc42-IRSp53 complexes.
The activated complex then mobilizes actin nucleators such as Ena/VASP proteins to the filament ends near the membrane.
Ena/VASP accumulation displaces the capping proteins and promotes filament elongation.
Simultaneously, IRSp53 clusters phosphatidylinositol 4,5-bisphosphate molecules at the inner leaflet of the membrane, inducing a curvature.
The combined outcome of increased membrane asymmetry and actin elongation deforms the membrane, structuring the filopodium.
As the filopodium extends, fascin proteins cross-link the actin filaments to form tight bundles.
This bundle gives rigidity to the filopodial structure to sustain the extracellular force and membrane tension.

mechanism of filopodia formation

Mechanism of Filopodia Formation

Filopodia are thin, actin-rich cellular protrusions that play an important role in many fundamental cellular functions. They vary in their occurrence, length, and positioning in different cell types, suggesting their diverse roles.
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication between two cells. For example, the formation of filopodial bridges between two adjacent endothelial or epithelial cells is important for the subsequent establishment of adherens junctions. In addition, filopodia can also help the cells to reach and internalize distant targets, such as pathogens.
Filopodia Formation and Disassembly
Actin nucleation, elongation, and bundling are critical for filopodia formation and function. The filopodia core comprises 12-20 actin filaments spaced 12 nm apart. Bundling of these filaments by fascin is crucial to give filopodia the rigidity to maintain its elongated shape.
The disassembly of actin filaments during the retraction phase involves periodic helical and rotational motion of the actin shaft and is regulated by several factors. For instance, capping proteins promote filopodial retraction by shielding the polymerizing ends of the filaments from further elongation. RhoA kinase activity also regulates actin polymerization within filopodia.

Filopodia are thin, actin-rich cellular protrusions that play an important role in many fundamental cellular functions. They vary in their occurrence, ...

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JoVE Core

Cell Biology

Unit 1

Cell Polarization and Migration

KEY TERMS AND CONCEPTS

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 clear example is the filopodial bridge between two adjacent endothelial or epithelial cells. This bridge helps set up adherens junctions, which are strong cell-cell connections. Filopodia can also help cells reach and internalize distant targets, such as pathogens.

Filopodia depend on actin nucleation, elongation, and bundling. Their core contains about 12 to 20 actin filaments spaced about 12 nm apart. Fascin bundles these filaments and gives filopodia the rigidity needed to keep their long, thin shape.

Filopodia also need controlled disassembly during retraction. This process involves periodic helical and rotational motion of the actin shaft and is regulated by several factors. Capping proteins promote retraction by blocking the growing ends of the filaments, and RhoA kinase activity also helps regulate actin polymerization within filopodia.

Filopodia in Cell Movement and Contact

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...

actin polymerization and cell motility

Actin Filaments in Cell Movement

Actin filaments help cells move, divide, and take in material from outside the cell. Actin is a family of globular proteins that is very abundant in eukaryotic cells. It makes up about 1 to 5 percent of total cell protein concentration. Actin monomers can join together to form a polarized network called the actin cytoskeleton. This network creates pushing, pulling, and resistance forces that support cell migration. Cell movement often follows repeated steps of front-edge protrusion, attachment...

types of membrane protrusions

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...

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...

role of myosin in cell migration

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...

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...

chemotaxis and direction of cell migration

chemotaxis-and-direction-of-cell-migration

How Cells Follow Chemical Gradients

Cells follow chemical gradients by sensing cues in their environment and changing their cytoskeleton to move toward or away from them. This directional movement is called chemotaxis. It helps guide many processes, including embryogenesis, development, immune response, tissue repair and regeneration, and reproduction. Chemical signals can act as attractants or repellents. In axon development, for example, chemoattractants and chemorepellents help direct a growing axon toward the correct target.

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 filopodia help cells move, anchor, and communicate, and how actin, fascin, capping proteins, and RhoA kinase shape these protrusions.

Filopodia in Cell Movement and Contact | 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.

Filopodia in Cell Movement and Contact

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