scholarly journals Direct visualization of the binding and internalization of a ferritin conjugate of epidermal growth factor in human carcinoma cells A-431.

1979 ◽  
Vol 81 (2) ◽  
pp. 382-395 ◽  
Author(s):  
H T Haigler ◽  
J A McKanna ◽  
S Cohen
Keyword(s):  
Plasma Membrane ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Carcinoma Cells ◽  
Biologically Active ◽  
Molar Ratio ◽  
Multivesicular Bodies ◽  
Egf Receptors ◽  
Human Carcinoma ◽  
Epidermal Growth

We have prepared a conjugate of epidermal growth factor (EGF) and ferritin that retains substantial binding affinity for cell receptors and is biologically active. Glutaraldehyde-activated EGF was covalently linked to ferritin to produce a conjugate that contained EGF and ferritin in a 1:1 molar ratio. The conjugate was separated from free ferritin by affinity chromatography using antibodies to EGF. Monolayers of human epithelioid carcinoma cells (A-431) were incubated with EGF:ferritin at 4 degrees C and processed for transmission electron microscopy. Under these conditions, approximately 6 X 10(5) molecules of EGF:ferritin bound to the plasma membrane of each cell. In the presence of excess native EGF, the number of bound ferritin particles was reduced by 99%, indicating that EGF:ferritin binds specifically to cellular EGF receptors. At 37 degrees C, cell-bound EGF:ferritin rapidly redistributed in the plane of the plasma membrane to form small groups that were subsequently internalized into pinocytic vesicles. By 2.5 min at 37 degrees C, 32% of the cell-bound EGF:ferritin was localized in vesicles. After 2.5 min, there was a decrease in the proportion of conjugate in vesicles with a concomitant accumulation of EGF:ferritin in multivesicular bodies. By 30 min, 84% of the conjugate was located in structures morphologically identified as multivesicular bodies or lysosomes. These results are consistent with other morphological and biochemical studies utilizing 125I-EGF and fluorescein-conjugated EGF.

scholarly journals Transit of epidermal growth factor through coated pits of the Golgi system.

1982 ◽  
Vol 94 (1) ◽  
pp. 207-212 ◽  
Author(s):  
M C Willingham ◽  
I H Pastan
Keyword(s):  
Plasma Membrane ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Carcinoma Cells ◽  
Coated Pits ◽  
Human Carcinoma ◽  
Golgi System ◽  
Reticular System ◽  
Entire Cell ◽  
Epidermal Growth

Using the direct conjugate of epidermal growth factor (EGF) and horseradish peroxidase, we have followed the entry of EGF into KB (human carcinoma) cells. EGF initially was found bound diffusely to the entire cell surface at 4 degrees C; on warming to 37 degrees C, EGF was found clustered in clathrin-coated pits on the plasma membrane in 1 min or less. Within 1-2 min at 37 degrees C, EGF began to accumulate in receptosomes within the cell and remained there for up to 10 min. At 10-13 min after warming to 37 degrees C, EGF was found in thin reticular membranous elements of the Golgi system, as well as concentrated in the clathrin-coated pits present on these membranes. By 15 min after warming, EGF began to be delivered to lysosomes located near the Golgi system. These findings suggest that clathrin-coated pits in the Golgi reticular system accumulate EGF before delivery to lysosomes.

scholarly journals Rapid stimulation of pinocytosis in human carcinoma cells A-431 by epidermal growth factor.

1979 ◽  
Vol 83 (1) ◽  
pp. 82-90 ◽  
Author(s):  
H T Haigler ◽  
J A McKanna ◽  
S Cohen
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Biological Activities ◽  
Fluid Phase ◽  
Fold Increase ◽  
Carcinoma Cells ◽  
Tumor Promoter ◽  
Metabolic Inhibitors ◽  
Human Carcinoma ◽  
Epidermal Growth

Horseradish peroxidase (HRP) uptake was used to measure fluid-phase pinocytosis in monolayers of human epithelioid carcinoma cells (A-431). Histochemistry confirmed that cell-associated HRP was restricted to intracellular vesicles. Biochemical methods showed that HRP uptake in control cultures was directly proportional to the duration of exposure. The addition of low concentrations of epidermal growth factor (EGF) to the incubation media produced a 10-fold increase in the initial rate of pinocytosis. The EGF effect was rapid (within 30 s) but transient; the rate of pinocytosis returned to control levels within 15 min. Metabolic inhibitors reduced the EGF-stimulated rate of pinocytosis by greater than 90%. A conjugate of EGF and ferritin (F:EGF) was used to simultaneously compare the intracellular locations of EGF and HRP. Much of F:EGF was internalized in approximately 100-nm vesicles, while most of the HRP was located in much larger vesicles (range 0.1--1.2 micrometer) which also contained F:EGF. The tumor-promoter 12-0-tetradecanoyl-phorbol-13-acetate, which shares several biological activities with EGF, was also effective in stimulating an increase in the rate of pinocytosis.

scholarly journals Epidermal growth factor receptor activation is localized within low-buoyant density, non-caveolar membrane domains

1999 ◽  
Vol 337 (3) ◽  
pp. 591-597 ◽  
Author(s):  
Mark G. WAUGH ◽  
Durward LAWSON ◽  
J. Justin HSUAN
Keyword(s):  
Plasma Membrane ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Receptor Activation ◽  
Cell Fractionation ◽  
Membrane Domains ◽  
Egf Receptors ◽  
Cell Extracts ◽  
Epidermal Growth

Increasing evidence for the organization of cell-surface proteins and lipids into different detergent-insoluble rafts led us to investigate epidermal growth factor (EGF) receptor activation in the plasma membranes of A431 carcinoma cells, using a combination of cell fractionation and immunoprecipitation techniques. Density-gradient centrifugation of sodium carbonate cell extracts revealed that the vast majority of both stimulated and unstimulated EGF receptors were concentrated in a caveolin-rich light membrane (CLM) fraction, with the biochemical characteristics of detergent-insoluble glycolipid-rich domains (DIGs). However, ultrastructural analysis of the CLM fraction revealed that it contained a heterogeneous collection of vesicles, some with sizes greater than that expected for individual caveolae. Experiments with detergent-solubilized cells and isolated CLMs indicated that, in contrast with caveolin, EGF receptors were unlikely to be localized to DIG domains. Furthermore, immunoisolation of caveolin from CLMs revealed that EGF receptor activation occurs in a compartment distinct from caveolae. Similarly, using an anti-(EGF receptor) antibody, the bulk of the cellular caveolin was not co-immunoprecipitated from CLMs, thereby confirming that these two proteins reside in separate membrane domains. The deduction that caveolar signalling and EGF receptor activation occur in separable rafts argues for a multiplicity of signal transduction compartments within the plasma membrane. In addition, by demonstrating that EGF receptor activation is compartmentalized within low-density, non-caveolar regions of the plasma membrane, it is also shown that the co-localization of proteins in a CLM fraction is insufficient to prove caveolar localization.

scholarly journals Distribution of mRNA for human epiregulin, a differentially expressed member of the epidermal growth factor family

1997 ◽  
Vol 326 (1) ◽  
pp. 69-75 ◽  
Author(s):  
Hitoshi TOYODA ◽  
Toshi KOMURASAKI ◽  
Daisuke UCHIDA ◽  
Sigeo MORIMOTO
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cell Lines ◽  
Tumour Cell ◽  
Biologically Active ◽  
Soluble Form ◽  
Egf Receptors ◽  
Epidermal Growth ◽  
Tumour Cell Lines ◽  
Egf Family

We have recently identified epiregulin as a new growth regulator and a member of the epidermal growth factor (EGF) family. Epiregulin has certain characteristics that are different from those of the classical members of the EGF family, EGF and transforming growth factor α, including mitogenic responses on several normal cells and binding to EGF receptors on epidermoid carcinoma A431 cells. In the present study we cloned and identified the expression of human epiregulin transcript. The human epiregulin gene encoded a 163-residue putative transmembrane precursor containing an EGF-like domain in the internal segment, and the structural organization was similar to that of other members of the EGF family that bind to EGF receptors. Northern blot analysis showed the expression of human epiregulin to be mainly on peripheral blood macrophages and the placenta in normal tissues, and was highest on epithelial tumour cell lines in various types of tumour cell lines. The expression profile was quite different from that of other members of the EGF family in normal and tumour cells. Recombinant expression in mammalian cells also showed that human epiregulin was secreted as a soluble form of approx. 5 kDa that is biologically active on the basis of the stimulation of DNA synthesis. Our findings suggest that epiregulin is involved in certain physiological processes such as maintenance or development of normal cell growth, and the progression of carcinomas.

scholarly journals Epidermal Growth Factor Enhances Cellular Uptake of Polystyrene Nanoparticles by Clathrin-mediated Endocytosis

2017 ◽  
Author(s):  
Le Thi Minh Phuc ◽  
Akiyoshi Taniguchi
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cellular Uptake ◽  
Epithelial Cell Line ◽  
Egf Receptors ◽  
A431 Cells ◽  
Polystyrene Nanoparticles ◽  
Human Carcinoma ◽  
Uptake Efficiency ◽  
Epidermal Growth

The interaction between nanoparticles and cells has been studied extensively, but most research has focused on the effect of various nanoparticle characteristics, such as size, morphology, and surface charge, on the cellular uptake of nanoparticles. In contrast, there have been very few studies to assess the influence of cellular factors, such as growth factor responses, on the cellular uptake efficiency of nanoparticles. The aim of this study was to clarify the effects of epidermal growth factor (EGF) on the uptake efficiency of polystyrene nanoparticles (PS NPs) by A431 cells, a human carcinoma epithelial cell line. The results showed that EGF enhanced the uptake efficiency of A431 cells for PS NPs. In addition, inhibition and localization studies of PS NPs and EGF receptors (EGFRs) indicated that cellular uptake of PS NPs is related to the binding of EGF-EGFR complex and PS NPs. Different pathways are used to enter the cells depending on the presence or absence of EGF. In the presence of EGF, cellular uptake of PS NPs is via clathrin-mediated endocytosis, whereas in the absence of EGF, uptake of PS NPs does not involve clathrin-mediated endocytosis. Our findings indicate that EGF enhances cellular uptake of PS NPs by clathrin-mediated endocytosis. This result could be important for developing safe nanoparticles and their safe use in medical applications.

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