What does membrane ruffling do?
Membrane ruffling (also known as cell ruffling) is the formation of a motile cell surface that contains a meshwork of newly polymerized actin filaments. A number of actin-binding and organizing proteins localize to membrane ruffles and potentially target to transducing molecules.
What is macropinocytosis in biology?
Biology of Adenovirus Cell Entry Macropinocytosis is the engulfment and uptake process of large amounts of fluids and membranes. It occurs by actin-dependent membrane protrusion and retraction, and results in large intracellular vacuoles (>0.2 μM), referred to as macropinosomes, which can mature to late endosomes.
What cells do macropinocytosis?
While B cells have not previously been considered candidates for active macropinocytosis, a recent study has indicated that B cells are capable of macropinocytosis in the context of pathogen infection. Raji cells, a human B lymphoblast cell line, exhibits very little membrane ruffling and macropinocytosis at rest [67].
What triggers macropinocytosis?
Macropinocytosis is usually initiated by external stimulation. The stimulus is commonly in the form of growth factors that trigger activation of receptor tyrosine kinases (RTKs). These, in turn, activate a signalling cascade that induces changes in the dynamics of actin filaments and trigger plasma membrane ruffling.
What is ruffling cell?
INTRODUCTION. Membrane ruffling (also known as cell ruffling) is the formation of actin rich membrane protrusions. This occurs in cellular zones undergoing rapid reorganization of the plasma membrane and often precedes the formation of a lamellipodium.
What happens in macropinocytosis?
Macropinocytosis is a form of endocytosis in which cells ingest extracellular fluid and solutes into relatively large endocytic vesicles called macropinosomes. In some cells, macropinocytosis occurs continuously whereas in others it is initiated by receptor–ligand interactions at the cell surface.
Is macropinocytosis receptor mediated?
Macropinocytosis is mediated by the actin cytoskeleton and is independent of clathrin and membrane receptors.
What are lamellipodia made of?
Lamellipodia are thin, sheet-like membrane protrusions found at the leading edge (front) of motile cells such as endothelial cells, neurons, immune cells and epithelial cells. These structures are generally devoid of major organelles and are instead composed of a dense and dynamic network of actin filaments.
Is macropinocytosis nonspecific?
However, immature DCs constitutively macropinocytose (Sallusto et al., 1995). Macropinocytosis is a nonselective form of endocytosis. It has been unclear how internalized ligands are concentrated in macropinosomes.
How does macropinocytosis lead to cell death?
When macropinocytosis is upregulated in GBM cells by a quinine-derivative chemical, Vacquinol-1, massive membrane ruffling and macropinocytosis lead to cell death through excessive vacuolization and deformations in the plasma membrane ( Kitambi et al., 2014 ).
What causes the ruffling of the cell membrane?
Membrane ruffling is a characteristic feature of many actively migrating cells. When the membrane is unable to attach to the substrate, the membrane protrusion is recycled back into the cell. The ruffling of membranes is thought to be controlled by a group of enzymes known as Rho GTPases, specifically RhoA, Rac1 and cdc42.
What is the role of coat proteins in macropinocytosis?
One of the hallmarks of macropinocytosis is its reliance on the formation of expansive membrane ruffles within the plasma membrane, which contrasts the canonical, endocytic pathways that depend on coat proteins such as clathrin and caveolin ( Doherty and McMahon, 2009 ).
What is the difference between micropinocytosis and macropinocytes?
Macropinocytosis is a form of endocytosis that accompanies cell surface ruffling. It is distinct in many ways from the better characterized micropinocytosis, which includes clathrin-coated vesicle endocytosis and small uncoated vesicles.