In
cell biologyCell biology is an academic discipline that studies cells – their physiological properties, their structure, the organelles they contain, interactions with their environment, their life cycle, division and death. This is done both on a microscopic and molecular level...
, a
bleb is an irregular bulge in the plasma membrane of a cell caused by localized decoupling of the
cytoskeletonThe cytoskeleton is a cellular "scaffolding" or "skeleton" contained within the cytoplasm. The cytoskeleton is present in all cells; it was once thought this structure was unique to eukaryotes, but recent research has identified the prokaryotic cytoskeleton...
from the plasma membrane.
Blebbing is the term used to describe the formation of blebs and is sometimes referred to as
zeiosis.
During
apoptosisApoptosis is the process of programmed cell death that may occur in multicellular organisms. Programmed cell death involves a series of biochemical events leading to a characteristic cell morphology and death; in more specific terms, a series of biochemical events that lead to a variety of...
(programmed cell death), the cell's cytoskeleton breaks up and causes the membrane to bulge outward.
In
cell biologyCell biology is an academic discipline that studies cells – their physiological properties, their structure, the organelles they contain, interactions with their environment, their life cycle, division and death. This is done both on a microscopic and molecular level...
, a
bleb is an irregular bulge in the plasma membrane of a cell caused by localized decoupling of the
cytoskeletonThe cytoskeleton is a cellular "scaffolding" or "skeleton" contained within the cytoplasm. The cytoskeleton is present in all cells; it was once thought this structure was unique to eukaryotes, but recent research has identified the prokaryotic cytoskeleton...
from the plasma membrane.
Blebbing is the term used to describe the formation of blebs and is sometimes referred to as
zeiosis.
Physiological Functions
During
apoptosisApoptosis is the process of programmed cell death that may occur in multicellular organisms. Programmed cell death involves a series of biochemical events leading to a characteristic cell morphology and death; in more specific terms, a series of biochemical events that lead to a variety of...
(programmed cell death), the cell's cytoskeleton breaks up and causes the membrane to bulge outward. These bulges may separate from the cell, taking a portion of
cytoplasmThe cytoplasm is the part of a cell that is enclosed within the cell membrane. In eukaryotic cells, the cytoplasm contains organelles, such as mitochondria, which are filled with liquid that is kept separate from the rest of the cytoplasm by biological membranes. The contents of the cell nucleus...
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
actinActin is a globular, roughly 42-kDa protein found in all eukaryotic cells where it may be present at concentrations of over 100 μM. It is also one of the most highly-conserved proteins, differing by no more than 20% in species as diverse as algae and humans...
content.
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 IIAMyosin, heavy chain 9, non-muscle is a protein which in humans is encoded by the MYH9 gene.-Clinical significance:MYH9 polymorphisms are thought to contribute to glomerulosclerosis and non-diabetic end stage renal disease in African Americans....
and was shown to lower the affinity of
myosinMyosins are a large family of motor proteins found in eukaryotic tissues. They are responsible for actin-based motility.Following the discovery by Pollard and Korn of enzymes with myosin-like function in Acanthamoeba castellanii, a large number of divergent myosin genes have been discovered...
with
actinActin is a globular, roughly 42-kDa protein found in all eukaryotic cells where it may be present at concentrations of over 100 μM. It is also one of the most highly-conserved proteins, differing by no more than 20% in species as diverse as algae and humans...
, thus altering the contractile forces that impinge on the cytoskeleton-membrane interface.