Signal Transduction Pathways-Part 2web.mit.edu/7.61/restricted/pdfs/lect5_signal_trans.pdfPIP-2 The...
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1 Signal Transduction Pathways-Part 2 Proliferation Survival Differentiation Apoptosis Cytoskeleton LIGANDS RECEPTORS ADAPTORS EFFECTORS OUTPUTS RTK-P RTK Ligand Signaling Kinase* Kinase R Ligand Signaling Phosphatase Receptor-intrinsic kinases Receptor-associated kinases RTKs EGFRs, InsRs, PDGFRs, VEGFRs, FGFRs, many others TGF ! R family Phosphatase Cytokine Rs - JAKs T/B cell Rs - SrcFK - ZAP70/Syk
Transcript of Signal Transduction Pathways-Part 2web.mit.edu/7.61/restricted/pdfs/lect5_signal_trans.pdfPIP-2 The...
1
Signal Transduction Pathways-Part 2
ProliferationSurvival
Differentiation
Apoptosis
Cytoskeleton
LIGANDS
RECEPTORS
ADAPTORS
EFFECTORS
OUTPUTS
RTK-P
RTK
Ligand
Signaling
Kinase*
Kinase
R
Ligand
Signaling
Phosphatase
Receptor-intrinsic kinases
Receptor-associated kinases
RTKs
EGFRs, InsRs,
PDGFRs, VEGFRs,
FGFRs, many others
TGF!R family
Phosphatase
Cytokine Rs - JAKs
T/B cell Rs - SrcFK
- ZAP70/Syk
2
Protein Modules Recruiting Signaling Proteins
to Receptors and to the Membrane
G"!# and arrestins serve somewhat similar functions for GPCRs
Different Mechanisms for Activating
Signaling Proteins
Recruitment
plus Activation
& Phosphorylation
Recruitment with
Conformational
Change -> Activation
Recruitment plus
Phosphorylation
-> Activation
3
Negative Feedback Regulation
GRKs and arrestins serve somewhat similar functions for GPCRs
Potential Delivery of Receptors to the Nucleus
Carpenter, Curr. Opin Cell Bio. 15:143-148 (2003)
Two-step cleavage
Cytoplasmic domain
translocates to
nucleus
?
?
Translocation of
intact R-L complex
to nucleus
Functions?
Notch
signaling
4
Protein Tyrosine Phosphatases
Protein Tyrosine Phosphatases
5
T Cell Receptor Signaling
Src family kinase ITAM-binding
(2xSH2) kinase
MHC/peptide
CD3 complexTCR
CD45
ITAM motif
YxxLx6-8YxxL
ITIM motif - binds phophatases
L/V/SxYxxL/V x15-30 L/V/SxYxxL/V
Structure of PTPase domain
D1 from receptor-like
Protein phosphatase-"
Bilwes et al.
Nature 382:555-559
(1996) - structure
Jiang et al.
Nature 401:606-610
(1999) - analysis
wedge
active
site
6
Different Mechanisms for Activating
Signaling Proteins
Recruitment
plus Activation
& Phosphorylation
Recruitment with
Conformational
Change -> Activation
Recruitment plus
Phosphorylation
-> Activation
Protein kinase C (PKC)
The Phosphatidylinositol 4,5 bisphosphate (PIP2) system:
PI->PI(4)P->PI(4,5)P2
OHOH
OH
P
1
4
56
23 P
P
OHOH
OH
P
1
4
56
23 P
O
O
O
O
PHOSPHATIDYLINOSITOL 4,5-BIS PHOSPHATE
O P O
O
O
O
O
O
O
HO
Diacyl glycerol (DAG)
PL-C
+
IP3
Phospholipase-C: PL-C
2-8% of membrane lipid is PI, 10-20% of PI are poly phosphorylated
Nomenclature: Ins(x,y,z)P3 x,y,z are the positions of Phosphate;
Ins(4)P - D-myo-inositol 4-monophosphate; Ins(1,4,5)P3 - D-myo-
inositol 1,4,5-bisphosphate; Ptdins - phosphatidylinositol
Phosphatidyl Inositol 4,5 bisphosphate (PI 4,5P2)
PIP-2
The Phosphatidylinositol 4,5 bisphosphate (PIP2) system:
PI->PI(4)P->PI(4,5)P2
OHOH
OH
P
1
4
56
23 P
P
OHOH
OH
P
1
4
56
23 P
O
O
O
O
PHOSPHATIDYLINOSITOL 4,5-BIS PHOSPHATE
O P O
O
O
O
O
O
O
HO
Diacyl glycerol (DAG)
PL-C
+
IP3
Phospholipase-C: PL-C
2-8% of membrane lipid is PI, 10-20% of PI are poly phosphorylated
Nomenclature: Ins(x,y,z)P3 x,y,z are the positions of Phosphate;
Ins(4)P - D-myo-inositol 4-monophosphate; Ins(1,4,5)P3 - D-myo-
inositol 1,4,5-bisphosphate; Ptdins - phosphatidylinositol
IP3
Phospholipase C (PL-C)
+
DAG (diacylglycerol) Ca++
A central player in signal transduction
PI-3-Kinase
Polyphospho-inositols (PIP3)
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PI3K
8
The PI3K / Akt-PKB/ PTEN Network
Sulis and Parsons. TICB Sep 2003
PI(3,4)P2
SHIP
9
cAMP
Chemotaxis to cAMP in the Slime Mold,
Dictyostelium discoideum
Protein kinase C (PKC)
Ca++
The Phosphatidylinositol 4,5 bisphosphate (PIP2) system:
PI->PI(4)P->PI(4,5)P2
OHOH
OH
P
1
4
56
23 P
P
OHOH
OH
P
1
4
56
23 P
O
O
O
O
PHOSPHATIDYLINOSITOL 4,5-BIS PHOSPHATE
O P O
O
O
O
O
O
O
HO
Diacyl glycerol (DAG)
PL-C
+
IP3
Phospholipase-C: PL-C
2-8% of membrane lipid is PI, 10-20% of PI are poly phosphorylated
Nomenclature: Ins(x,y,z)P3 x,y,z are the positions of Phosphate;
Ins(4)P - D-myo-inositol 4-monophosphate; Ins(1,4,5)P3 - D-myo-
inositol 1,4,5-bisphosphate; Ptdins - phosphatidylinositol
Phospholipase C - PIP2 -> DAG + IP3
PIP-2
The Phosphatidylinositol 4,5 bisphosphate (PIP2) system:
PI->PI(4)P->PI(4,5)P2
OHOH
OH
P
1
4
56
23 P
P
OHOH
OH
P
1
4
56
23 P
O
O
O
O
PHOSPHATIDYLINOSITOL 4,5-BIS PHOSPHATE
O P O
O
O
O
O
O
O
HO
Diacyl glycerol (DAG)
PL-C
+
IP3
Phospholipase-C: PL-C
2-8% of membrane lipid is PI, 10-20% of PI are poly phosphorylated
Nomenclature: Ins(x,y,z)P3 x,y,z are the positions of Phosphate;
Ins(4)P - D-myo-inositol 4-monophosphate; Ins(1,4,5)P3 - D-myo-
inositol 1,4,5-bisphosphate; Ptdins - phosphatidylinositol
IP3
Phospholipase C (PL-C)
+
DAG (diacylglycerol)
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Phospholipases C
RPTK-activated
G protein-activated - G"q/ G"11
Products - DAG and IP3
PH domain
Generation of Many
Diverse and Important
Lipid Second
Messengers
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Protein kinase C (PKC)
Ca++
The Phosphatidylinositol 4,5 bisphosphate (PIP2) system:
PI->PI(4)P->PI(4,5)P2
OHOH
OH
P
1
4
56
23 P
P
OHOH
OH
P
1
4
56
23 P
O
O
O
O
PHOSPHATIDYLINOSITOL 4,5-BIS PHOSPHATE
O P O
O
O
O
O
O
O
HO
Diacyl glycerol (DAG)
PL-C
+
IP3
Phospholipase-C: PL-C
2-8% of membrane lipid is PI, 10-20% of PI are poly phosphorylated
Nomenclature: Ins(x,y,z)P3 x,y,z are the positions of Phosphate;
Ins(4)P - D-myo-inositol 4-monophosphate; Ins(1,4,5)P3 - D-myo-
inositol 1,4,5-bisphosphate; Ptdins - phosphatidylinositol
Phospholipase C - PIP2 -> DAG + IP3
PIP-2
The Phosphatidylinositol 4,5 bisphosphate (PIP2) system:
PI->PI(4)P->PI(4,5)P2
OHOH
OH
P
1
4
56
23 P
P
OHOH
OH
P
1
4
56
23 P
O
O
O
O
PHOSPHATIDYLINOSITOL 4,5-BIS PHOSPHATE
O P O
O
O
O
O
O
O
HO
Diacyl glycerol (DAG)
PL-C
+
IP3
Phospholipase-C: PL-C
2-8% of membrane lipid is PI, 10-20% of PI are poly phosphorylated
Nomenclature: Ins(x,y,z)P3 x,y,z are the positions of Phosphate;
Ins(4)P - D-myo-inositol 4-monophosphate; Ins(1,4,5)P3 - D-myo-
inositol 1,4,5-bisphosphate; Ptdins - phosphatidylinositol
IP3
Phospholipase C (PL-C)
+
DAG (diacylglycerol)
Alexandra C Newton: Regulation of protein kinase C Current Opinion in Cell Biology1997 9 : 161-167.
Protein Kinase C - Structures
DAG Ca++ Catalytic domain
Regulatory domains
PhorbolestersDAG
",! #
$, %, &
'
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Model for the regulation of protein kinase C
Alexandra C Newton: Regulation of protein kinase C Current Opinion in Cell Biology1997 9 : 161-167.
Protein Kinases C - Activated by DAG or Other Lipid
Second Messengers
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IP3 Activates Calcium Release to Cytoplasm
Ca++ Signaling
Berridge, M.J., Bootman, M.D. and Roderick, H.L. (2003)
Calcium Signalling: Dynamics, Homeostasis and Remodelling.
Nat. Rev. Molec. Cell Biol. 4: 517-528.
Berridge, M. J., Lipp, P. and Bootman, M.D. (2000)
The Versatility and Universality of Calcium Signalling.
Nat. Rev. Molec. Cell Biol. 1: 11-21.
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Ca++: intracellular [Ca2+] usually ~10-7- rises to 10-6-10-5 M
Ca++ enters cytosol from ER and/or extracellular fluid
Transient increases (sparks, waves) - quickly pumped out of
cytoplasm and/or binding proteins sequester.
Source, frequency and amplitude of spikes can influence effects
of the signal
Some effectors bind Ca++ directly (e.g., PK-C).
Many use intermediates: troponin C (muscle), S100 family,
recoverin, frequenin, and best understood…
Calmodulin (17kDa 4 binding sites,
Kd for 2 carboxy-term = 10-7 M, for 2 N-term = 2.4x10-6)
Ca++ binding exposes hydrophobic side chains:
Ca++ Signaling
a) Ca2+ -free (apoCaM) b) 4xCa2+ -CaM
Structure of Calmodulin (CaM):
Binds and activates
downstream effectors.
e.g. CaCM-activated
kinase (CAMkinase).
CAM kinase is a
dodecamer of similar
subunits - normally
autoinhibited by
internal
pseudosubstrate
-activation can be
-Stabilized by
-autophosphorylation
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Activation of PKA
cAMP-activated protein kinase
Another example of relief of inhibition.
Targets PKA to specific locations(eg nucleus, CSK, SR)
and also anchors targets nearby
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APOPTOSIS
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Apoptosis Signaling
TNF Receptor Family
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Apoptosis adaptors
Caspases
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Bcl-2 Family
Wnt signaling pathways
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Hedgehog (Hh) signaling pathways
Philip W. Ingham and Andrew P. McMahonGenes and Development 15: 3059-3087 ( 2001)Hedgehog signaling in animal development: paradigms and principleshttp://hedgehog.sfsu.edu/
No Hh
Genes repressed
(incl. Ptc)
Moderate Hh
Some genes
activated
(incl. Ptc)
High levels of Hh
More genes
activated
No Hh
No transcription
Transcription
activated
Hh present
Kalderon TICB 12:523-531(2002)
Similarities between the Hedgehog and Wnt signaling pathways.
Nusse Development 130:5297-305 (2003)
Wnts and Hedgehogs: lipid-modified proteins and similarities
in signaling mechanisms at the cell surface.
