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In cell biology, a bleb is an irregular bulge in the plasma membrane of a cell caused by localized decoupling of the cytoskeleton from the plasma membrane^[1]. Blebbing is the term used to describe the formation of blebs and is sometimes referred to as zeiosis.

The process of apoptosis, with blebbing shown in the middle illustration

[edit] Physiological Functions

During apoptosis (programmed cell death), the cell's cytoskeleton breaks up and causes the membrane to bulge outward^[2]. These bulges may separate from the cell, taking a portion of cytoplasm with them, to become known as apoptotic bodies. Phagocytic cells eventually consume these fragments and the components are recycled (see figure).

Blebbing also has important functions in other cellular processes, including cell locomotion, cell division, and physical or chemical stresses. The types of blebs vary greatly, including variations in bleb growth rates, size, contents, and actin content.

[edit] Pharmacology

A chemical known as blebbistatin was recently shown to inhibit the formation of blebs. This agent was discovered in a screen for small molecule inhibitors of nonmuscle myosin IIA and was shown to lower the affinity of myosin with actin ^[3][4], thus altering the contractile forces that impinge on the cytoskeleton-membrane interface.

[edit] Notes

[edit] References

• Charras GT, Coughlin M, Mitchison TJ, Mahadevan L (Mar 2008). "Life and times of a cellular bleb". Biophys J. 94 (5): 1836–53. doi:10.1529/biophysj.107.113605. PMID 17921219. 
• Charras GT, Hu CK, Coughlin M, Mitchison TJ (Nov 2006). "Reassembly of contractile actin cortex in cell blebs". J. Cell Biol. 175 (3): 477–90. doi:10.1083/jcb.200602085. PMID 17088428. 
• Dai J, Sheetz MP (Dec 1999). "Membrane tether formation from blebbing cells". Biophys. J. 77 (6): 3363–70. PMID 10585959. PMC 1300608. http://www.biophysj.org/cgi/pmidlookup?view=long&pmid=10585959. 
• Drug Stops Motor Protein, Shines Light on Cell Division - FOCUS March 21, 2003. Retrieved April 8, 2008.
• Hagmann J, Burger MM, Dagan D (Jun 1999). "Regulation of plasma membrane blebbing by the cytoskeleton". J. Cell. Biochem. 73 (4): 488–99. doi:10.1002/(SICI)1097-4644(19990615)73:4<488::AID-JCB7>3.0.CO;2-P. PMID 10733343. 

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