scholarly journals Activation of phospholipase D by α-thrombin or epidermal growth factor contributes to the formation of phosphatidic acid, but not to observed increases in 1,2-diacylglycerol

1992 ◽  
Vol 285 (2) ◽  
pp. 395-400 ◽  
Author(s):  
T M Wright ◽  
S Willenberger ◽  
D M Raben
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Phosphatidic Acid ◽  
Phospholipase D ◽  
Myristic Acid ◽  
Transient Activation ◽  
Lipid Species ◽  
Epidermal Growth

The receptor-mediated activation of a phosphatidylcholine-hydrolysing phospholipase D (PLD) has recently been described. We investigated the effect of alpha-thrombin and epidermal growth factor (EGF) on cellular PLD activity in order to determine the role of this enzyme in mitogen-induced increases in phosphatidic acid and sn-1,2-diacylglycerol. In the presence of ethanol, stimulation of [3H]myristic acid-labelled quiescent IIC9 cells with alpha-thrombin or EGF resulted in a rapid increase in radiolabelled phosphatidyl-ethanol which reached a plateau at 1 min, indicating the rapid and transient activation of PLD. We observed a concomitant decrease in the mitogen-stimulated increase of radiolabelled phosphatidic acid. In contrast, ethanol did not significantly effect the elevation of sn-1,2-diacylglycerol levels stimulated by alpha-thrombin or EGF as determined by measurement of sn-1,2-diacylglycerol mass or the appearance of [3H]1,2-diacylglycerol. A novel lipid, detected by two-dimensional t.l.c. analysis, was generated in [3H]myristic acid-labelled cells stimulated with alpha-thrombin, but not EGF, in the presence of ethanol. Treatment in vitro of cellular lipids isolated from [3H]myristic acid-labelled cultures with PLD in the presence of ethanol also resulted in the generation of this novel lipid species, supporting the role of this enzyme in its production. These data indicate that in quiescent IIC9 cells: (a) alpha-thrombin or EGF rapidly and transiently activates a PLD; (b) although this activation is responsible for part of the mitogen-induced increases in phosphatidic acid, it does not contribute to induced increases in sn-1,2-diacylglycerol; and (c) activation of this enzyme appears to be involved in the formation of a novel lipid generated in response to alpha-thrombin, but not EGF, in IIC9 fibroblasts.

scholarly journals 14-3-3 Facilitates Ras-Dependent Raf-1 Activation In Vitro and In Vivo

1998 ◽  
Vol 18 (7) ◽  
pp. 3947-3955 ◽  
Author(s):  
Sandrine Roy ◽  
Robert A. McPherson ◽  
Ann Apolloni ◽  
Jun Yan ◽  
Annette Lane ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Specific Activity ◽  
Membrane Recruitment ◽  
Oncogenic Ras ◽  
Epidermal Growth

ABSTRACT 14-3-3 proteins complex with many signaling molecules, including the Raf-1 kinase. However, the role of 14-3-3 in regulating Raf-1 activity is unclear. We show here that 14-3-3 is bound to Raf-1 in the cytosol but is totally displaced when Raf-1 is recruited to the plasma membrane by oncogenic mutant Ras, in vitro and in vivo. 14-3-3 is also displaced when Raf-1 is targeted to the plasma membrane. When serum-starved cells are stimulated with epidermal growth factor, some recruitment of 14-3-3 to the plasma membrane is evident, but 14-3-3 recruitment correlates with Raf-1 dissociation and inactivation, not with Raf-1 recruitment. In vivo, overexpression of 14-3-3 potentiates the specific activity of membrane-recruited Raf-1 without stably associating with the plasma membrane. In vitro, Raf-1 must be complexed with 14-3-3 for efficient recruitment and activation by oncogenic Ras. Recombinant 14-3-3 facilitates Raf-1 activation by membranes containing oncogenic Ras but reduces the amount of Raf-1 that associates with the membranes. These data demonstrate that the interaction of 14-3-3 with Raf-1 is permissive for recruitment and activation by Ras, that 14-3-3 is displaced upon membrane recruitment, and that 14-3-3 may recycle Raf-1 to the cytosol. A model that rationalizes many of the apparently discrepant observations on the role of 14-3-3 in Raf-1 activation is proposed.

scholarly journals Epidermal growth factor prevents oligomeric amyloid-β induced angiogenesis deficits in vitro

2016 ◽  
Vol 36 (11) ◽  
pp. 1865-1871 ◽  
Author(s):  
Kevin P Koster ◽  
Riya Thomas ◽  
Alan WJ Morris ◽  
Leon M Tai
Keyword(s):  
Endothelial Cell ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Amyloid Β ◽  
Brain Endothelial Cell ◽  
Cerebrovascular Dysfunction ◽  
Endothelial Cell Cultures ◽  
Epidermal Growth

Cerebrovascular dysfunction is a critical component of Alzheimer’s disease (AD) pathogenesis. Oligomeric amyloid-β42 (oAβ42) is considered a major contributor to AD progression. However, data are limited on the role of oAβ42 in brain endothelial cell vessel degeneration/angiogenesis, including the interaction with angiogenic mediators. Thus, the current study determined the effect of oAβ42 on angiogenesis in vitro, utilizing single brain endothelial cell cultures and triple cultures mimicking the microvascular unit (MVU: brain endothelial cells, astrocytes, and pericytes). oAβ42 dose-dependently reduced angiogenesis and induced vessel disruption. Critically, epidermal growth factor prevented oAβ42-induced deficits, implicating angiogenic pathways as potential therapeutics for AD.

scholarly journals Altered endocytosis of epidermal growth factor receptor in androgen receptor positive prostate cancer cell lines

2007 ◽  
Vol 38 (1) ◽  
pp. 51-66 ◽  
Author(s):  
Lorella Bonaccorsi ◽  
Daniele Nosi ◽  
Monica Muratori ◽  
Lucia Formigli ◽  
Gianni Forti ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Epidermal Growth Factor Receptor ◽  
Androgen Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cell Lines ◽  
Growth Factor Receptor ◽  
Epidermal Growth

Although androgens and the androgen receptor (AR) are involved in tumorigenesis of prostate cancer (PC) in initial phases, less clear is the role played in advanced androgen-independent (AI) stages of the disease. Several recent reports indicated that re-expression of AR in PC-derived cell lines determines a less aggressive phenotype of the cells. We have previously demonstrated that re-expression of AR decreases the invasion ability of PC3 cells in vitro by affecting signalling and internalization processes of epidermal growth factor receptor (EGFR). Here, we show that reduced EGFR internalization is also a characteristic of AR positive PC cell lines LNCaP and 22Rv1. Reduced internalization in PC3-AR cells is associated to a defective interaction between the EGFR and two adaptor proteins which mediate the endocytotic process, Grb2 and c-Cbl. As a consequence of such reduced interaction, ubiquitination of the receptor, which is mainly mediated by c-Cbl, is also altered. In addition, we show that internalized EGFR co-localizes with early endosome antigen-1, a marker of clathrin-mediated endocytosis, in PC3-Neo cells but not in AR positive cell lines. Conversely, EGFR maintains co-localization with caveolin-1 after EGF stimulation in PC3-AR cells. These data suggest that expression of AR affects clathrin-mediated endocytosis pathway of EGFR, which, according to recent findings, plays an essential role in the completeness of signalling of the receptor. Taken together, these data emphasize the role of AR in the regulation of EGFR endocytotic trafficking and active signalling in PC cells. In view of the role of EGFR signalling in invasion of carcinoma cells, our data may explain the lower invasive phenotype observed in AR-positive cell lines.

scholarly journals In-vitro maturation of human germinal vesicle stage oocytes: role of cumulus cells and epidermal growth factor in the culture medium

1998 ◽  
Vol 13 (6) ◽  
pp. 1638-1644 ◽  
Author(s):  
P. T. Goud ◽  
A. P. Goud ◽  
C. Qian ◽  
H. Laverge ◽  
J. Van der Elst ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
In Vitro Maturation ◽  
Culture Medium ◽  
Germinal Vesicle ◽  
Cumulus Cells ◽  
Epidermal Growth

Defining the role of the epidermal growth factor receptor in pancreatic cancer grown in vitro

2003 ◽  
Vol 186 (5) ◽  
pp. 431-436 ◽  
Author(s):  
Alan J Durkin ◽  
P.Mark Bloomston ◽  
Alexander S Rosemurgy ◽  
Natalie Giarelli ◽  
Diane Cojita ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Growth Factor Receptor ◽  
Epidermal Growth
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