Related Experiment Video
Updated: Jul 2, 2026
10:50
Nanopodia - Thin, Fragile Membrane Projections with Roles in Cell Movement and Intercellular Interactions
Published on: April 3, 2014
Filopodia formation induced by active mDia2/Drf3.
J Block1, T E B Stradal, J Hänisch
1Cytoskeleton Dynamics Group, Helmholtz Centre for Infection Research, Braunschweig, Germany.
Journal of Microscopy
|August 30, 2008
Summary
Human formin mDia2/Drf3 actively nucleates actin filaments for filopodia formation, challenging the lamellipodia-centric model. This suggests de novo actin nucleation drives filopodia extension, not just elongation from existing networks.
Area of Science:
- Cell Biology
- Cytoskeleton Dynamics
- Molecular Cell Biology
Background:
- Filopodia are actin-based cell protrusions often linked to lamellipodia formation.
- Current models propose filopodia arise from actin filament elongation within lamellipodia.
- Filopodia formation occurs independently of the Arp2/3 complex, essential for lamellipodia.
Purpose of the Study:
- To investigate the role of human formin mDia2/Drf3 in filopodia formation.
- To determine if filopodia formation relies on de novo actin nucleation or filament elongation.
- To analyze the impact of mDia2/Drf3 variants on cell morphology and actin organization.
Main Methods:
- Ectopic expression of GFP-tagged full-length and constitutively active mDia2/Drf3 (Drf3DeltaDAD).
- Microscopy to observe filopodia morphology, actin filament organization, and protein localization.
- Microarray analysis to assess Drf3 expression levels in various cell lines.
Main Results:
- Active Drf3DeltaDAD, but not full-length Drf3, induced filopodia formation and localized to their tips.
- Drf3DeltaDAD expression levels correlated with filopodia shape (rod-shaped to club-shaped).
- Drf3-induced filopodia and lamellipodia-like structures suggest de novo actin nucleation and involvement of fascin.
Conclusions:
- Drf3-induced filopodia formation and extension occur via de novo actin nucleation, not solely convergent elongation.
- The findings challenge the exclusive model of filopodia formation from lamellipodia networks.
- Variable Drf3 expression highlights the need for cell-type-specific analysis of formin functions in actin dynamics.
Related Concept Videos
01:39Mechanism 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...
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...
01:31Mechanism of Lamellipodia Formation
Cells migrating in response to external stimuli form lamellipodia, which are thin membrane protrusions supported by a mesh of linked, branched, or unbranched actin filaments. These actin filaments interact with myosin motor proteins, creating the dynamic actomyosin complex within the cytoskeleton. Contractility, or the ability to generate contractile stress, is inherent to the actomyosin complex. It helps cells detect the stiffness of the surrounding ECM and exert contractile force for...
01:16Cell 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...
Blebbing Through the Matrix
In multicellular...
01:09Cell Migration
Cell migration, the process by which cells move from one location to another, is essential for the proper development and viability of organisms throughout their life. When cells are not able to migrate properly to their ordained locations, various disorders may occur. For example, disruption in cell migration causes chronic inflammatory diseases such as arthritis.
01:35Cancer Cell Migration through Invadopodia
Invadosome is a broad category of cell surface structures with proteolytic activity that degrades the extracellular matrix (ECM). Invadosomes are present in normal cell types, including macrophages, endothelial cells, and neurons, as well as tumor cells. Although the macrophage podosomes and tumor cell invadopodia are classified as invadosomes, they have different structures, molecular pathways, and functions. Podosomes are short structures that last for a few minutes. However, invadopodia can...
01:21Cell Polarization by Rho Proteins
Cell polarity is the asymmetric distribution of cellular and membrane components, making one side of the cell different from the other. This polarity is essential to many processes such as embryogenesis, axon migration, glucose transport across epithelial cells, and directional cell migration. A migrating cell responds to intracellular or extracellular signals via molecular cascades that reorganize the actin cytoskeleton to establish this polarity. In these cells, the Rho family proteins Cdc42,...