EGFR` - Biol512

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Epidermal Growth Factor
Receptor(EGFR) signaling pathway
Samantha
03/09/11
Outline
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EGFR signaling pathway
EGFR endocytosis
Crosstalk
Clinic therapy
The significant of EGFR signaling pathway
http://www.informedicalcme.com/egfr/tyrosine-kinase-inhibitors-sensitivity/
EGFR signaling pathway
• EGF Receptors
• Downstream of EGFR
• A new role for Egfr in cancer
The discovery of epidermal growth factor
http://nobelprize.org/nobel_prizes/medicine/laureates/1986/press.html
The discovery of epidermal growth factor
http://nobelprize.org/nobel_prizes/medicine/laureates/1986/press.html
EGF Receptor Members
Table 15-4 Molecular Biology of the Cell (© Garland Science 2008)
EGF Receptor Members
EGF receptor members:
Vertibrates: EGFR; ErbB2; ErbB3; ErbB4
C. elegans: Let-23
Drosophila: DER
C. elegans and Drosophila have served as useful model systems
for studying the signaling processes triggered by the EGF
receptor.
Recall:
RTKs have 3 functional regions:
1. N-terminal extracellular
region w/ 1 or more
ligand-binding sites
2. Single transmembrane
-helix domain
3. C-terminal cytoplasmic
region w/ catalytic
domain +
phosphorylation sites
Lodish (2004) Fig 14-5
EGF receptor structure
ErbB3--has
impaired kinase
activity, and only
signals when
heterodimerizing
with another
receptor type.
Bogdan et al. 2000
EGF receptor structure
Eigenbrot et al;
Activation of the EGF receptor
Ligands:
Spices
Ligands
ErbB2
doesn’t bind Lin-3,
any EGFC. elegans
a soluble TGFa-like ligand.
like ligands on its own,
Drosophila
Spitz, Vein, Grken, Keren
but can heterodimerize
Human
More than dozen ligands
with other EGF-bound
receptors.
ErbB3
has impaired kinase
activity, and only
signals when
heterodimerizing with
another receptor type.
Roepstorff et al.2008
Recall:
Receptor tyrosine kinase activation
by dimerization
only transphosphorylation
Lodish (2004) Fig 14-5
cis- &/or transphosphorylation
Activation of the EGF receptor
In the cytoplasm, the two tyrosine
kinase domains form an asymmetric
dimer, with the c-terminal lobe.
Juxtamembrane region of EGFR
stabilizes formation of the asymmetric
kinase dimer.
EGFR is not activated by
autophosphorylation of the activation
loop.
Hubbard et al. (2009)
Downstream of EGFR
Bogdan et al. 2000
Downstream of EGFR
SIGMA-ALDRICH
Negative regulator of EGFR signaling
Bogdan et al. 2000
Recall:
Models of Signaling in Membrane Rafts
Simons & Toomre 2000
Model 1a:
- raft-associated receptors activated
by dimerization.
Model 1b:
- dimerization increases affinity for
raft.
Model 2:
- clustering of multiple rafts triggers
signaling
Lipid rafts and EGFR
methyl-B-cyclodextrin
cholesterol depletion
inhibition of EGF-stimulated PI turnover.
BUT, led to an enhancement of EGF-stimulated
MAP kinase activity.
Lipid rafts disruption appears to have both positive and negative
effects on receptor tyrosine kinase-mediated signaling
Lipid rafts and EGFR
methyl-B-cyclodextrin
cholesterol depletion
The enhancement of EGF binding and receptor autophosphorylation
An increase in intrinsic receptor kinase activity .
EGF receptor function is suppressed when the receptor is localized
to lipid rafts.
A new role of Egfr as a transcription factor
Wen, 2010
A new role of Egfr in cancer
Engelman etal. 2008
Outline
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EGFR signaling pathway
EGFR endocytosis
Crosstalk
Clinic therapy
EGFR endocytosis
• Ligand-induced endocytosis of EGFR
• Novel way of EGFR endocytosis
Negative regulator of EGFR signaling
Bogdan et al. 2000
Clathrin-mediated EGFR endocytosis
Grb-dependent pathway:
Grb2-Cb1 complex is recruited to C-terminal of EGFR.
Adds mono-or polyubiquitins to EGFR.
Activated EGFR is transported to clathrin coated pits.
Roepstorff et al. 2008
Clathrin-mediated EGFR endocytosis
Grb-independent pathway
Cb1 can mediate ubiquination of “X” internalization of EGFR.
EGFR can directly interact with AP-2
Sorkin et al.2008
Clathrin-mediated EGFR endocytosis
A, EGFR is recycled back to the plasma membrane.
B, EGFR will be degraded in lysosomes.
Clathrin-mediated EGFR endocytosis & signaling
Signal transduction
Membrane trafficking
Signal transduction molecules affect membrane trafficking.
Membrane trafficking can regulate signal transduction events.
The initial phase of EGFR signaling is endocyotosis-independent, but
Later events require clathrin-mediated EGFR Endocytosis(CME).
AKT and ERK require CME,
EGFR-activated DNA synthesis depends on functional CME.
Clathrin-independent EGFR endocytosis
Under conditions of receptor overexpression and/or high
ligand concentrations, clathrin-independent internalization
determines the overall rate of the EGFR uptake into the cell
A-431 cells
Formation of
micro-and
macropinocytic
vesiles
COS cells
Large
vesicular
structures
Several types of cells
Vesicular-tubular endocytic
compartment originated from
the plasma membrane dorsal
ruffles
The novel function of EGFR dimerization in
internalization
Inhibition of EGFR kinase activation did not block EGF-induced
EGFR internalization.
Absence of EGFR dimerization, EGF binding can not stimulate
EGFR endocytosis.
EGFR dimerization can mediate the EGF-induced cellular
process independently of its role in activating EGFR
tyrosien kinase.
Outline
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EGFR signaling pathway
EGFR endocytosis
Crosstalk
Clinic therapy
Cross-talk
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EGFR signaling and Notch pathway
EGFR signaling and GPCR
EGFR and Wnt signaling
EGF and insulin cell signaling pathway
EGFR signaling and Notch pathway
Hasson and Paroush, 2006
EGFR signaling and GPCR
Prenzel et al .2000
EGFR and Wnt signaling
EGF and insulin cell signaling pathway
Outline
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EGFR signaling pathway
EGFR endocytosis
Crosstalk
Clinic therapy
Clinic therapy
• EGFR inhibitor
• New possible therapies
Clinic Therapy
• Monoclonal antibodies (mAbs)directed against the EGFR
extracellular domain
• Small molecule tyrosine kinase inhibitors (TKIs)directed
against the tyrosine kinase domain.
EGFR inhibitor
Natural inhibitors include
potato carboxypeptidase
inhibitor(PCI), which
contains a small cysteinerich module, called a T-knot
scaffold, that is shared by
several different protein
families, including the EGF
family.
https://www. medscape.com
New possible therapies
• Nuclear EGFR and EGFR-targeted Therapy
• Therapy based on EGFR kinase-indepenent activity
References
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1, Robert N.Jorissen, Francesca Walker, Normand Pouliot , Thomas P.J.Garrett, Colin W. Ward, and Antony
W.Burgess. Epidermal growth factor receptor: mechanisms of activation and signaling. Experimental Cell
Research 284(2003)31-53.
2, Sven Bogdan and Christian Klambt. Epidermal growth factor receptor signaling. Current Biology (2000)
Vol10 No8.
3, Shiaw-Yih Lin, Keishi Makino, Weiya Xia, Angabin Matin, Yong Wen, Ka Yin Kwong, Lilly Bourguignon and
Mien-Chie Hung. Nuclear localization of EGF receptor and its potential new role as a transcription factor.
Nature Cell Biology Vol3(2001).
4, Zhang Weihua, Rachel Tsan, Wei-Chien Huang, Qiuyu Wu, Chao-Hua Chiu, Isaiah J. Fidler, and Mien-Chie
Huang. Survival of Cancer Cells is Maintained by EGFR independent of Its Kinase Activity. Cancer Cell 13,
385-393, (2008).
5, Jeffrey A. Engelman and Lewis C. Cantley. A sweet new role for EGFR in cancer. Cancer Cell13(2008).
6, Kirstine Roepstorff, Lene Grovdal, Michael Grandal, Mads Lerdrup, BoVanDeurs. Endocytic downregulation
of ErbB receptors: mechanisms and relevance in cancer. Histochem Cell Biol(2008)129:563-578.
7, Amandio V Vieira, Christophe Lamaze, Sandra L. Schmid. Control of EGF Receptor Signaling By ClathrinMediated Endocytosis. Science Vol274(1996)
8, Alexander Sorkin, Lai Kuan Goh. Endocytosis and Intracellular trafficking of ErbBs. Experimental Cell
Research 315(2009)683-696.
References
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9.Norbert Prezel, Esther Zwick, Michael Leserer and Axel Ullrich. Tyrosine Kinase signaling in breast cancer
Epidermal growth factor receptor: Convergence point for signal integration and diversification. Breast
Cancer Research(2000), 2:184-190.
10,Qian Wang, Greg Villeneuve and Zhixiang Wang. Control of epidermal growth factor receptor endocytosis
by receptor dimerization, rater than receptor kinase activation. 2005 EuROPEAN MOLECULAR BIOLOGY
ORGANIZATION.
11, Rafal Zielinski, Pawel F Przytycki, Jie Zheng, David Zhang, Teresa M Przytycka and Jacek Capala. The
crosstalk between EGF, IGF, and Insuin cell signaling pathways-computational and experimental analysis.
BMC Systems Biology 2009, 3:88
12, Tianhui Hu, Cunxi Li. Convergence between Wnt-B-catenin and EGFR signaling in cancer. Molecular cancer
2010, 9:236.
13, P Hasson and Z Paroush. Crosstalk between the EGFR and other signaling pathways at the level of the
global transcriptional corepressor Groucho/TLE. British Journal of Cancer(2006)94,771-775.
14, Elizabeth A Musgrove, Wnt signallin gvia the epidermal growth factor receptor: a role in breast cancer?
Breast Cancer Res 2004, 6:65-68.
15, Stevan R. Hubbard. The Juxtamembrane Region of EGFR Takes Center Stage. Cell137, June 26 2009.

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