Download Wnt signaling

Manifestation of Novel Social Challenges of the
European Union
in the Teaching Material of
Medical Biotechnology Master’s Programmes
at the University of Pécs and at the University
of Debrecen
Identification number: TÁMOP-4.1.2-08/1/A-2009-0011
Manifestation of Novel Social Challenges of the
European Union
in the Teaching Material of
Medical Biotechnology Master’s Programmes
at the University of Pécs and at the University
of Debrecen
Identification number: TÁMOP-4.1.2-08/1/A-2009-0011
Tímea Berki and Ferenc Boldizsár
Signal transduction
WNT SIGNALING
TÁMOP-4.1.2-08/1/A-2009-0011
Discovery of Wnts
Wnt genes:
• Wingless gene in Drosophila
melanogaster
• Int gene in mice
• 24 has been discovered
• 19 are expressed in mammals
• 10 receptor genes - Frizzleds
TÁMOP-4.1.2-08/1/A-2009-0011
Wnt family proteins
Comprises of 19 secreted glycoproteins
controlling a variety of developmental
processes:
• Cell fate specification
• Cell proliferation
• Cell polarity and cell migration
• Different types of cancers
• Various processes of aging
Frizzled (Fz) family
receptors
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• They are 7-TM receptors; however, assembly
of an active Wnt-Fz receptor complex also
requires the presence of a co-receptors, the
low-density lipoprotein related protein 5
and 6 (LRP5/6)
• Canonical pathway activators: Wnt1, Wnt3,
Wnt3a, Wnt7a, Wnt7b, Wnt8
• Non-canonical pathway activators: Wnt5a,
Wnt4, Wnt11
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Canonical pathway
• In developing thymocytes or in thymic epithelium
• Signals from the Wnt-Fz-LRP6 complex lead to the
phosphorylation of three domains of Dishevelled
(Dvl), a family of cytosolic signal transducer
molecules.
• Activation of Dvl ultimately leads to phosphorylation
and consequently inhibition of GSK-3
• Inhibition of GSK-3 results in stabilisation and
consequent cytosolic accumulation of -catenin, which
then translocates into the nucleus,
• -catenin forms active transcription complexes with
members of the T-Cell Factor (LEF1, TCF1, TCF3, TCF4)
transcription factor family and transcription
initiator p300.
• Successful assembly of the transcription complex
leads to the activation of various target genes
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Non-canonical pathways
• Independent from -catenin
• Branches into the:
1 Polar cell polarity (PCP) or c-Jun-N
Terminal Kinase (JNK)/Activating
Protein (AP1) dependent
2 Ca2+ or Protein kinase C
(PKC)/Calmodulin Kinase
(CaMKII)/Nuclear Factor of
Activating T- cells (NFAT) dependent
pathways
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Wnt signaling pathways
Wnt/Ca2+
Canonical pathway
Planar cell polarity
LRP5/6
Wnt
Wnt5a
Frizzled
Wnt11
Frizzled
Frizzled
Stbm
Plasma membrane
Cytoplasm
Axin
?
G proteins?
Dsh
DIX
PDZ
DIX
DEP
PLC
Prickle
Dsh
PDZ
?
Ca2+
DEP
Daam1
RhoA
Rac
ROCK
JNK
GSK3
Axin
-catenin
No Wnt signal
PKC
APC
-TrCP
CaMKII
Calcineurin
P
NFAT
Cytoskeletal
rearrangment
-catenin
-catenin
Nucleus
LEF/
TCF
NFAT
Gene transcription
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Canonical Wnt pathway
LRP5/6
Wnt8
Frizzled
Dkk1
Plasma membrane
Cytoplasm
Krm
Dsh
Axin
DIX
PDZ
DEP
-catenin
TCF3
Nucleus
Anterior genes
-catenin in cellular
adhesion
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Wnt
Frizzled
Cadherin
Axin
-catenin
-catenin
GSK3
Cadherin
-catenin
-catenin
Cadherin
Dsh
-catenin
-catenin
Cadherin
-catenin
-catenin
Plasma membrane
-catenin APC
P
-catenin
P
+ Wnt signal No Wnt signal
-catenin
degradation
Adherens
junction
-catenin
LEF/TCF
Nucleus
Cytoplasm
Transcription
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Alzheimer’s disease I
AP
Excitotoxicity
Activated microglia
Cell-cycle activation
Abnormal DNA synthesis
NO
DNA damage
+
p53
Bax
Dkk1
-
Fast AP toxicity
Apoptosis
Wnt
Delayed AP toxicity
Development of NFTs
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Alzheimer’s disease II
Early stage
Late stage
Wnt
Wnt
Wnt
Frizzled
Frizzled
Frizzled
Dkk1
Dkk1
bAP
Krm
Krm
Akt
Dsh
P
PI3K
PI3K
Akt
Akt
GSK3
-catenin
Nucleus
-catenin
LEF/
TCF
GD3 synthasecyclin D1
GSK3
GSK3
↓Phosphorylation of tau
↑Phosphorylation of tau
Inhibition of Wnt and Tcf
signaling in the canonical
pathway
TÁMOP-4.1.2-08/1/A-2009-0011
Wnt
Frp
Frizzled
Dominant negative Frizzleds
Nkd 1 and 2
Dsh
Dominant negative Dsh-s
CK-1,2
Frat
GSK3
APC
Axin
-catenin
PP2A
Nucleus
b-TrCP
-catenin
TCF4
ICAT
TCF4
Growth
PKC isoforms in Wnt
signalling
•PKC
•PKCd
•PKCz
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The classical view of three
independent Wnt signalling
pathways
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1 The canonical pathway is the first and best
characterized Wnt pathway. Signals are
coming through the 7 transmembrane domains
of Frizzled-receptors, than Dsh is
phosphorylated and signal is transmitted via
-catenin to TCF/LEF in the nucleus.
2 Ca-dependent Wnt signaling is transmitted by
Frizzled-s and G-proteins and the
intracellular signaling molecules are CaMKII
and different izotypes of PKCs. Inhibitory
signals can use TAK and NLK to get into the
nucleus. One of the key targets is NF-AT.
3 Planar cell polarity pathway is Ca dependent
and using JNK as well as PKCs to transduce
In what diseases are Wnt
signalling pathways involved
?
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• Inflammation
• Fibrosis
• Cancer
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Wnt target genes
INFLAMMATION
TISSUE REPAIR AND
REMODELLING
IL-1, Il-8, IL-6, MMP-s
FGF10, TGFb, BMP4, MMP-s
Wnt Target genes
Canonical pathway
(-catenin/TCF)
Cyclin D1, MMP-s, c-myc, Cox-2, c-jun,
Fra-1, VEGFR, EGFR
Ca2+ pathway
(NFAT, NFkB)
IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-8,
IL-15, IFN-, GMCSF, TNF-, ICAM-1
PCP pathway
(AP1)
Cyclin D1, MMP-s, FasL, Bim, Bcl3, FL1,
GMCSF
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Rheumatoid arthritis
CD34+ bone marrow
Increased Wnt5a
ogenitorcell infiltration
Inflammatory
stimuli
Leukocyte infiltration
Synoviocytes
Wnt1
Wnt5a
Wnt11
Wnt13
Fz-2
Fz-5
Fz-7
IL6, IL8, IL15,
metallo-proteinases
Joint destruction
Molecular changes of Wnt4
signaling in the aging
thymus
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• Wnt4 uses mainly the -catenin dependent canonical
signaling pathway
• Wnt4 expression is decreasing during aging in the
thymus
• The receptors of Wnt4 signaling are Frizzled-4 and
Frizzled-6
• The expression pattern of Wnt4 receptors is changing
during thymic senescence
• During aging the balance moves towards the Fz-6,
transducing negative Wnt signals
• PKCd is modulating intracellularly the Wnt4 signaling
mechanism
• CTGF - a target gene of Wnt4 signals- expression is
increasing
• CTGF is a negative regulator of b-catenin dependent