Related Experiment Video
Updated: Jul 19, 2026
10:27
Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
Published on: March 9, 2012
EGF induces recycling membrane to form ruffles
M S Bretscher1, C Aguado-Velasco
1MRC Laboratory for Molecular Biology, Cambridge, UK. msb@mrc-lmb.cam.ac.uk
Current Biology : CB
|June 25, 1998
Summary
Epidermal growth factor (EGF) triggers cell membrane ruffles via Rac. New ruffle surfaces originate from internal endosomes, not the plasma membrane, revealing Rac
Area of Science:
- Cell biology
- Molecular signaling
- Membrane trafficking
Background:
- Epidermal growth factor (EGF) stimulates KB cells to form membrane ruffles.
- Rac GTPases mediate the signaling pathway for EGF-induced membrane ruffling.
- Ruffles are rich in cytoskeletal components like actin and ezrin.
Purpose of the Study:
- To determine the origin of new membrane surfaces in EGF-induced ruffles.
- To investigate whether ruffle membranes derive from adjacent plasma membrane or internal endocytosed pools.
Main Methods:
- Observation of KB cells responding to EGF.
- Analysis of receptor distribution on newly formed ruffle membranes.
- Focus on transferrin and low-density lipoprotein (LDL) receptors as markers of endocytic pathways.
Main Results:
- EGF-induced ruffles on KB cells show enrichment of transferrin and LDL receptors.
- These receptors are known to be concentrated in endosomal membranes via clathrin-mediated endocytosis.
- The findings indicate that ruffle surfaces are not derived from the adjacent plasma membrane.
Conclusions:
- The surfaces of EGF-induced ruffles originate from the exocytosis of internal membrane from the endocytic cycle.
- Rac's primary function involves redirecting the exocytosis of recycling membrane to specific ruffle formation sites.
- This study elucidates a novel mechanism for membrane dynamics during cell signaling.
Related Concept Videos
00:58Recycling Endosomes and Transcytosis
The recycling endosome, also known as the endosomal recycling compartment (ERC), is a part of the slow-recycling process of the endocytic pathway. Molecules internalized through receptor-mediated endocytosis are either degraded in the lysosomes or are recycled to the plasma membrane through the fast- or slow-recycling route.
The recycling endosome is not a single organelle but an extensively tubulated network of recycling pathways. It functions in storing molecules or transporting them across...
The recycling endosome is not a single organelle but an extensively tubulated network of recycling pathways. It functions in storing molecules or transporting them across...
01:14Rab Proteins
Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane.
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
01:15Receptor Downregulation in MVBs
Multivesicular bodies (MVBs) are mature endosomes that sort ubiquitinated proteins and then fuse with lysosomes to degrade the sorted proteins. Epidermal growth factor (EGF) and its receptor (EGFR) form a complex that can be internalized through endocytosis, sorted into an MVB, and later degraded.
The EGFR can initiate signaling pathways that lead to cell proliferation, migration, and differentiation. Overexpression of EGFR stimulates cells to proliferate. Excessive EGFR activation may...
The EGFR can initiate signaling pathways that lead to cell proliferation, migration, and differentiation. Overexpression of EGFR stimulates cells to proliferate. Excessive EGFR activation may...
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...
01:22Role of Ephrin-Eph Signalling in Intestinal Stem Cell Renewal
Erythropoietin-producing hepatocellular carcinoma receptor (Eph) and its ligand, Eph receptor-interacting protein (Ephrin) were first discovered in the human carcinoma cell line, hence the name. Ephrin-Eph interaction guides cells to reach their appropriate location in adult tissues. They also play an essential role in the immune system by helping in immune cell migration, adhesion, and activation. Based on their structure and function, Eph is divided into two classes — EphA and EphB.