Name: blebbing in cell movement and cell death
Uploaded: 2023-04-30T10:17:16.000Z
Duration: 1 min 16 s
Channel: JoVE

The cell is internally lined with an actomyosin network that forms the cortex, and is linked to the cell membrane via linker proteins such as ezrin.
In response to appropriate signals, the cortical actin network destabilizes and ruptures, leading to localized detachment of the membrane from the cortex.
The internal hydrostatic pressure causes the detached membrane to swell outwards and rapidly fill with the cytoplasm, forming a rounded protrusion called a bleb.
Inside the bleb, a cytoskeletal regulator, Rnd3, prevents RhoA activation and inhibits the reassembly of the actin cortex, allowing further expansion of the bleb.
As the bleb expands, the Rnd3 concentration decreases, resulting in RhoA activation.
Activated RhoA promotes reassembly of actin and ezrin, thus re-establishing the cortex in the bleb.
Finally, myosin-II associates with and contracts the actin bundles, generating the force to retract the bleb and push the cell forward through the extracellular matrix.

cell motility through blebbing

Cell Motility through Blebbing

Blebs are a type of membrane protrusion formed by the internal hydrostatic pressure of the cytoplasm. Blebs are observed in several cell types, including fibroblasts, immune cells, and single-celled organisms like the amoeba. The primary function of blebs is cell locomotion and apoptosis, but they are also found during necrosis and cell division. The life cycle of a bleb comprises an initiation phase followed by the expansion and retraction phases.
Blebbing Through the Matrix
In multicellular organisms,&#160; migrating cells navigate through a complex three-dimensional path, squeezing their way between cells and through the extracellular matrix (ECM). The actin-driven membrane protrusions, such as filopodia&#160; and lamellipodia, aid in crawling across surfaces or between cells. In contrast, blebs allow the cells to navigate through narrow gaps between the components of the ECM. The initiation and expansion of blebs push the flexible plasma membrane through these small gaps while subsequent&#160; bleb retraction helps move the cell through this three-dimensional matrix.
Blebbing and Apoptosis
Apoptosis or programmed cell death is a sequential cascade of events that aid the death of a cell without damaging surrounding cells. Blebbing is a characteristic feature of this process. An apoptotic cell initiates multiple blebs on its surface, which pinch off to form tiny apoptotic blebs containing bits of cytoplasm and proteins from the primary cell. Other cells such as neutrophils and macrophages phagocytose these apoptotic blebs, and help recycle the cellular components. Apoptotic cells also produce larger blebs containing fragments of disrupted organelles such as mitochondria and nucleus.&#160;

Blebs are a type of membrane protrusion formed by the internal hydrostatic pressure of the cytoplasm. Blebs are observed in several cell types, including ...

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JoVE Core

Cell Biology

Unit 1

Cell Polarization and Migration

KEY TERMS AND CONCEPTS

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 such as filopodia and lamellipodia help cells crawl across surfaces or between cells, while blebs help cells pass through narrow gaps in the ECM. A bleb develops in stages, with initiation first, then expansion, and finally retraction to help the cell move forward.

Blebbing is also a key feature of apoptosis, which is programmed cell death. During apoptosis, a cell forms multiple blebs on its surface. Some of these blebs pinch off as small apoptotic blebs that contain bits of cytoplasm and proteins from the original cell. Neutrophils and macrophages can engulf these blebs and recycle the cell material. Apoptotic cells may also produce larger blebs that contain fragments of damaged organelles, including mitochondria and the nucleus.

Blebbing in Cell Movement and Cell Death

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...

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.

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 blebs help cells move through narrow gaps in the ECM and how blebbing supports apoptosis, including apoptotic blebs and cell recycling.

Blebbing in Cell Movement and Cell Death | 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.

Blebbing in Cell Movement and Cell Death

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