Name: cell surface protrusions in movement
Uploaded: 2023-04-30T11:17:32.000Z
Duration: 1 min 28 s
Channel: JoVE

Different types of membrane protrusions like lamellipodia, filopodia, invadopodia, and blebs are formed during cell migration or invasion.
They vary from each other in their morphological, structural, and functional characteristics and are carefully coordinated by several different molecules and signaling pathways.
Lamellipodia are flat, broad protrusions formed at the leading edge of motile cells such as neurons, and immune cells. They function as a driver during chemotaxis.
Unlike lamellipodia, filopodia are thin, needle-like projections that extend from the leading edge of some migrating cells to help them probe the environment.
In contrast to other types of protrusions, blebs are unique in their appearance and formation.
They are spherical membrane projections formed due to internal hydrostatic pressure in the cells, such as fibroblasts and immune cells.
Blebs are not only functional during migration but also other cellular processes such as apoptosis.
Cancer cells form a special type of protrusion called invadopodia.
Invadopodia are enriched with matrix proteinases that allow the invasive cancer cells to degrade the ECM barrier and spread to other parts of the body.

types of membrane protrusions

Types of Membrane Protrusions

The protrusion of the cell surface is an initial step for several cellular processes, including cell migration, phagocytosis, and neurite outgrowth. These membrane protrusions are a result of cytoskeletal rearrangement. The most&#160; widely observed cell protrusions include lamellipodia, pseudopodia, filopodia, microvilli, invadopodia, and podosomes. These protrusions can be of two types &#8212; static or dynamic.
The microvilli, an example of stable protrusions, are finger-like projections with a generally stable actin architecture. These brush-like extensions are found on the apical surface of epithelial cells lining internal organs, such as the intestine. They greatly increase the surface area for enhanced nutrient absorption.
Contrastingly, dynamic protrusions are primarily involved in cell migration. The majority of these structures use actin polymerization as the driving force for membrane deformation. Additionally, actin binds myosin motor proteins to form contractile bundles. The myosin motors pull on the actin filaments, thus rearranging them during migration. Based on their appearance, actin-dependent protrusions are classified as lamellipodia, pseudopodia, filopodia, and invadopodia.
Many migrating cells like keratinocytes or fibroblasts exhibit lamellipodia, which are thin, sheet-like projections at the leading edge of these cells. They are involved in the rapid migration of cells to sites of injury for repair and regeneration. Lamellipodia&#160; can extend bundled actin filaments to form finger-like projections called filopodia. For example,&#160; neurons form these outgrowths to sense environmental signals and rewire the nervous system after trauma.
Other membrane protrusions include the podosomes&#160; and invadopodia. While podosomes are transient peg-like structures developed by migrating cells like macrophages, invadopodia are projections produced by metastatic cells on the extracellular matrix. Additionally, invadopodia secrete proteolytic enzymes, degrading the extracellular matrix to break tissue architecture and metastasize into adjacent tissues. Lastly, blebs are spherical membrane projections formed due to internal hydrostatic pressure. They do not depend on the actin cytoskeleton for their enlargement. Fibroblasts and immune cells exhibit bleb formation for migration and other cellular processes such as apoptosis.

The protrusion of the cell surface is an initial step for several cellular processes, including cell migration, phagocytosis, and neurite outgrowth. These ...

Education

JoVE Core

Cell Biology

Unit 1

Cell Polarization and Migration

KEY TERMS AND CONCEPTS

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 apical surface of epithelial cells, such as the cells lining the intestine, and they increase surface area for nutrient absorption.

Dynamic protrusions are linked mainly to cell migration. Many of them depend on actin polymerization, which builds actin filaments and pushes the membrane outward. Actin also binds myosin motor proteins to form contractile bundles, and the myosin motors pull on the actin filaments during movement.

Based on shape, actin-dependent protrusions include lamellipodia, pseudopodia, filopodia, and invadopodia. Lamellipodia are thin, sheet-like projections at the leading edge of many migrating cells, including keratinocytes and fibroblasts. They help cells move quickly to injury sites for repair and regeneration, and they can extend bundled actin filaments into finger-like filopodia.

Filopodia are used by neurons to sense environmental signals and help rewire the nervous system after trauma. Podosomes are transient, peg-like structures formed by migrating cells such as macrophages. Invadopodia are made by metastatic cells on the extracellular matrix, and they secrete proteolytic enzymes that degrade the matrix so cells can break tissue architecture and spread into nearby tissues.

Blebs are another type of membrane protrusion. They are spherical projections formed by internal hydrostatic pressure, and their enlargement does not depend on the actin cytoskeleton. Fibroblasts and immune cells can form blebs during migration and in other processes such as apoptosis.

Cell Surface Protrusions in Movement

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...

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...

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

Explore how lamellipodia, filopodia, microvilli, podosomes, invadopodia, and blebs help cells move, absorb nutrients, and reshape tissues.

Cell Surface Protrusions in Movement | 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.

Cell Surface Protrusions in Movement

Description

Transcript

Tags