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A Clockwork Bleb: cytoskeleton, calcium, and cytoplasmic fluidity
Junichi Ikenouchi1, Kana Aoki1
1Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan.
Abstract:
When the plasma membrane (PM) detaches from the underlying actin cortex, the PM expands according to intracellular pressure and a spherical membrane protrusion called a bleb is formed. This bleb retracts when the actin cortex is reassembled underneath the PM. Whereas this phenomenon seems simple at first glance, there are many interesting, unresolved cell biological questions in each process. For example, what is the membrane source to enlarge the surface area of the PM during rapid bleb expansion? What signals induce actin reassembly for bleb retraction, and how is cytoplasmic fluidity regulated to allow rapid membrane deformation during bleb expansion? Furthermore, emerging evidence indicates that cancer cells use blebs for invasion, but little is known about how molecules that are involved in bleb formation, expansion, and retraction are coordinated for directional amoeboid migration. In this review, we discuss the molecular mechanisms involved in the regulation of blebs, which have been revealed by various experimental systems.
Insights
Cell membrane blebs form when the plasma membrane detaches from the actin cortex. This review explores the molecular mechanisms regulating bleb formation, expansion, and retraction, crucial for cell migration.
Area of Science:
- Cell Biology
- Biophysics
Background:
- Plasma membrane (PM) blebs form via detachment from the actin cortex, expanding due to intracellular pressure.
- Bleb retraction occurs upon actin cortex reassembly beneath the PM.
Purpose of the Study:
- To review the molecular mechanisms regulating bleb formation, expansion, and retraction.
- To address unresolved questions regarding membrane source, actin reassembly signals, and cytoplasmic fluidity during blebbing.
- To explore the role of blebbing in cancer cell invasion and directional migration.
Main Methods:
- Review of experimental systems and existing literature.
- Analysis of molecular signaling pathways involved in bleb dynamics.
- Examination of the role of blebbing in cell migration and invasion.
Main Results:
- Bleb formation involves plasma membrane detachment and expansion.
- Bleb retraction is mediated by actin cortex reassembly.
- Blebbing dynamics are regulated by specific molecular signals and cytoplasmic properties.
Conclusions:
- Blebbing is a complex cellular process with significant implications for cell motility.
- Understanding bleb regulation is key to deciphering cancer cell invasion mechanisms.
- Further research is needed to fully elucidate the coordination of bleb dynamics in directed cell migration.
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