Cross-talk among epidermal growth factor, Ap5A, and nucleotide receptors causing enhanced ATP Ca2+ signaling involves extracellular kinase activation in cerebellar astrocytes

2005 ◽  
Vol 81 (6) ◽  
pp. 789-796 ◽  
Author(s):  
Esmerilda G. Delicado ◽  
Ana I. Jiménez ◽  
Luz María G. Carrasquero ◽  
Enrique Castro ◽  
Mª Teresa Miras-Portugal
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cross Talk ◽  
Nucleotide Receptors ◽  
Kinase Activation ◽  
Epidermal Growth ◽  
Cerebellar Astrocytes

134. EPIDERMAL GROWTH FACTOR RECEPTOR/MAPK3/1 PATHWAY CROSS-TALK ENABLES GROWTH DIFFERENTIATION FACTOR 9 TO SIGNAL THROUGH SMAD2/3 IN MOUSE GRANULOSA CELLS

2009 ◽  
Vol 21 (9) ◽  
pp. 53
Author(s):  
M. Sasseville ◽  
L. J. Ritter ◽  
T. Nguyen ◽  
D. G. Mottershead ◽  
D. L. Russell ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Granulosa Cells ◽  
Cross Talk ◽  
Egf Receptor ◽  
Thymidine Incorporation ◽  
Differentiation Factor ◽  
Growth Differentiation Factor 9 ◽  
Epidermal Growth ◽  
Receptor Inhibitor

Oocyte-secreted growth differentiation factor 9 (GDF9) plays a critical role throughout folliculogenesis. It has been shown to control many functions of granulosa cells, including gene expression, steroidogenesis and proliferation. This study investigates the cellular requirements that allow GDF9 to act on granulosa cells. Our results showed that GDF9 (20 ng/ml)-stimulated mouse granulosa cells 3H-thymidine incorporation was inhibited by a type 1 receptor Alk4/5/7 inhibitor (SB431542, 5 μM), by an epidermal growth factor (EGF) receptor inhibitor (AG1478, 5μM) and a MEK1 inhibitor (U0126, 10 μM). Interestingly, activin A- and TGFβ-stimulated 3H-thymidine incorporation shared similar inhibitor sensitivity. Moreover, when denuded oocytes were used as the mitogenic agent, SB431542, AG1478 and U0126 all prevented the increase in 3H-thymidine incorporation. Oocyte-stimulated 3H-thymidine incorporation in secondary follicles and cumulus-oocyte complexes were also sensitive to Alk4/5/7, EGF receptor and MEK1 inhibition. Basal and EGF-stimulated levels of phopho-MAPK3/1 were inhibited by using the EGF receptor inhibitor, but were not affected by inhibition of Alk4/5/7 or by adding GDF9 in granulosa cells. Using granulosa cells transfected with a SMAD3-luciferase reporter construct, GDF9-stimulated SMAD3 response could be inhibited by Alk4/5/7, EGFR and MEK1 inhibitors. Genes involved in cumulus cells expansion (Ptx3 and Has2) were upregulated in granulosa cells by co-culturing with denuded oocytes and that upregulation was inhibited by Alk4/5/7 as well as by EGF receptor inhibition. These results suggest that TGFβ superfamily members signalling through Smad2/3 share a common requirement of EGF receptor-dependant phospho-MAPK3/1 throughout folliculogenesis. These results strongly suggest that, apart from its role in the transmission of the ovulatory LH signal within the ovarian follicle, EGF receptor pathway might serve as modulators of GDF9 action on granulosa cells. Hence the interaction between endocrine and oocyte signalling may be mediated at the level of MAPK and Smad2/3 cross-talk in granulosa cells.

scholarly journals Structural Evidence for Loose Linkage between Ligand Binding and Kinase Activation in the Epidermal Growth Factor Receptor

2010 ◽  
Vol 30 (22) ◽  
pp. 5432-5443 ◽  
Author(s):  
Chafen Lu ◽  
Li-Zhi Mi ◽  
Michael J. Grey ◽  
Jieqing Zhu ◽  
Elizabeth Graef ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Growth Factor Receptor ◽  
Transmembrane Domains ◽  
Cross Linking ◽  
Hydrophobic Domain ◽  
Kinase Activation ◽  
Epidermal Growth

ABSTRACT The mechanisms by which signals are transmitted across the plasma membrane to regulate signaling are largely unknown for receptors with single-pass transmembrane domains such as the epidermal growth factor receptor (EGFR). A crystal structure of the extracellular domain of EGFR dimerized by epidermal growth factor (EGF) reveals the extended, rod-like domain IV and a small, hydrophobic domain IV interface compatible with flexibility. The crystal structure and disulfide cross-linking suggest that the 7-residue linker between the extracellular and transmembrane domains is flexible. Disulfide cross-linking of the transmembrane domain shows that EGF stimulates only moderate association in the first two α-helical turns, in contrast to association throughout the membrane over five α-helical turns in glycophorin A and integrin. Furthermore, systematic mutagenesis to leucine and phenylalanine suggests that no specific transmembrane interfaces are required for EGFR kinase activation. These results suggest that linkage between ligand-induced dimerization and tyrosine kinase activation is much looser than was previously envisioned.

scholarly journals Filamin A Modulates Kinase Activation and Intracellular Trafficking of Epidermal Growth Factor Receptors in Human Melanoma Cells

Endocrinology ◽  
2009 ◽  
Vol 150 (6) ◽  
pp. 2551-2560 ◽  
Author(s):  
Jennifer L. Fiori ◽  
Tie-Nian Zhu ◽  
Michael P. O'Connell ◽  
Keith S. Hoek ◽  
Fred E. Indig ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Intracellular Trafficking ◽  
Growth Factor Receptor ◽  
Degradation Pathway ◽  
Melanoma Cells ◽  
Actin Binding ◽  
Filamin A ◽  
Kinase Activation ◽  
Epidermal Growth

The actin-binding protein filamin A (FLNa) affects the intracellular trafficking of various classes of receptors and has a potential role in oncogenesis. However, it is unclear whether FLNa regulates the signaling capacity and/or down-regulation of the activated epidermal growth factor receptor (EGFR). Here it is shown that partial knockdown of FLNa gene expression blocked ligand-induced EGFR responses in metastatic human melanomas. To gain greater insights into the role of FLNa in EGFR activation and intracellular sorting, we used M2 melanoma cells that lack endogenous FLNa and a subclone in which human FLNa cDNA has been stably reintroduced (M2A7 cells). Both tyrosine phosphorylation and ubiquitination of EGFR were significantly lower in epidermal growth factor (EGF)-stimulated M2 cells when compared with M2A7 cells. Moreover, the lack of FLNa interfered with EGFR interaction with the ubiquitin ligase c-Cbl. M2 cells exhibited marked resistance to EGF-induced receptor degradation, which was very active in M2A7 cells. Despite comparable rates of EGF-mediated receptor endocytosis, internalized EGFR colocalized with the lysosomal marker lysosome-associated membrane protein-1 in M2A7 cells but not M2 cells, in which EGFR was found to be sequestered in large vesicles and subsequently accumulated in punctated perinuclear structures after EGF stimulation. These results suggest the requirement of FLNa for efficient EGFR kinase activation and the sorting of endocytosed receptors into the degradation pathway.

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