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Prion protein as a therapeutic target in Alzheimer’s diseasePrion protein as a therapeutic target in Alzheimer’s disease
Nigel Hooper
University of ManchesterUK
Prion protein and Alzheimer’s Prion protein and Alzheimer’s –– a connection?a connection?
- causative agent of transmissible spongiform encephalopathies (TSEs), e.g. Creutzfeldt-Jakob disease (CJD), BSE, scrapie, etc- cellular PrPC undergoes conformational change to infectious PrPSc
• Metal homeostasis• Anti-oxidant response• Cell signalling• Ligand/protein binding
� Cases of co-existent Alzheimer’s and CJD pathology(Hainfellner et al. 1998; Voigtlander et al. 2001)
� Met/Val129 polymorphism in PRNP a risk factor for Alzheimer’s(Dermaut et al. 2003; Riemenschneider et al. 2004)
� PrPC to PrPSc conversion & Aβ production occur in cholesterol-rich lipid rafts(Cordy et al. 2003; Ehehalt et al. 2003; Taraboulos et al. 1995)
� APP & PrPC shed from the cell surface by the zinc metalloprotease ADAM10(Parvathy et al. 1998; Parkin et al. 2004; Taylor et al. 2009)
� PrPC inhibits the β-secretase cleavage of APP(Parkin et al. 2007; Griffiths et al. 2011)
• Ligand/protein binding
Cellular prion Cellular prion protein protein ((PrPPrPCC): ): a receptor for Aa receptor for Aββ oligomersoligomers
• Screened expression library of 225,000 mouse brain cDNAs225,000 mouse brain cDNAs
• PrPC the only specific, high-affinity receptor for Aβ oligomers (kd ~ 0.4 nM)
Cisse & Mucke (2009) Nature 457, 1090-1
Aβ natively
fibrilsprotofibrils
Deposit in senile plaques
Neurotoxic forms Neurotoxic forms of of amyloidamyloid--ββ
Fibrils
unfoldedmonomer
low-n 6mer 12mer(Aβ*56)
ADDLs(>56 kDa)
APF globulomer
Bind to neurons
Memory impairments
Toxicity and cell death
Alzheimer’s Disease
Rushworth & Hooper (2011) Int. J. Alzheimers Dis. Article ID 603052
Oligomers
Biophysical and immunological characterisation of ABiophysical and immunological characterisation of Aββ11--4242
oligomers (ADDLs)oligomers (ADDLs)
Tomic et al., 2009
Conformation-dependent antibodies
6E10(Aβ)
OC (fibrillar epitope)
A11 (pre-fibrillar epitope)
100 nm
monomer oligomer
5-6 nm Ø 10
17
26
55
170
﹜kDa
Aβoligomers
< tetramer< trimer
< monomer
Conformation-dependent antibodies
(Charlie Glabe, California)
A11 (pre-fibrillar
oligomers)
OC (fibrillar
oligomers)“Levels of soluble fibrillar oligomers detected by OC antibody are significantly elevated in multiple brain regions of AD patients”
Rushworth et al. (2013) J. Biol. Chem. 288, 8935
PrPPrPCC is required for the cellular binding of is required for the cellular binding of fibrillarfibrillar AAββ oligomers oligomers and activation of Fyn kinaseand activation of Fyn kinase
Rat hippocampal neurons
Rushworth et al. (2013) J Biol Chem 288, 8935
PrPPrPCC is GPI anchored and localised is GPI anchored and localised in cholesterolin cholesterol--rich, rich, detergentdetergent--resistant lipid raftsresistant lipid rafts
Fyn
PrPC
Disruption of lipid rafts prevents Disruption of lipid rafts prevents AAββ oligomeroligomer binding and binding and activation of Fyn activation of Fyn kinasekinase
Rushworth et al. (2013) J. Biol. Chem. 288, 8935
MβCD = methyl β-cyclodextrin, sequesters cholesterol
The transmembrane LRP1 is required for the binding and The transmembrane LRP1 is required for the binding and cytotoxicity of Acytotoxicity of Aββ oligomersoligomers
LRP1 = low-density
Rushworth et al. (2013) J. Biol. Chem. 288, 8935
LRP1 = low-density lipoprotein receptor-related protein 1
RAP = receptor-associated protein
AAββ oligomersoligomers promote the clustering of promote the clustering of PrPPrPCC and LRP1and LRP1
Rushworth et al. (2013) J. Biol. Chem. 288, 8935
PrPC
LRP1
Fy
n
lipid raft
Neuroprotection?
Membrane
Neurotoxic
Fy
n
P
Fy
n
Aββββ oligomers
Metabotropic glutamate receptor 5 Metabotropic glutamate receptor 5 (mGluR5) is (mGluR5) is a a coreceptorcoreceptorwith with PrPPrPCC for Afor Aβ β oligomersoligomers
Neuron 79, 887-902
AAββ oligomeroligomer binding stimulates the clustering of specific neuronalbinding stimulates the clustering of specific neuronalreceptors into aberrant signalling platforms at the synapsereceptors into aberrant signalling platforms at the synapse
Normal Alzheimer’s disease
Rushworth & Hooper (2011) Int. J. Alzheimers Dis. Article ID 603052
PrPPrPCC as a therapeutic target in Alzheimer’s disease?as a therapeutic target in Alzheimer’s disease?
But… But… PrPPrPCC has several physiological roles has several physiological roles
PrPC
PrPPrPCC inhibits the inhibits the amyloidogenicamyloidogenic processing of the amyloid processing of the amyloid precursor protein (APP)precursor protein (APP)
α-secretase β-secretase
n = 24
PrPPrPCC is reduced in sporadic Alzheimer’s brain and inversely is reduced in sporadic Alzheimer’s brain and inversely correlates with correlates with BACE1 activity, ABACE1 activity, Aββ and and BraakBraak stage stage
BACE1 activity
Whitehouse et al. (2013) PLoS ONE 8: e59554
Soluble Aβ Insoluble Aβ Braak stage
Prion protein in human hippocampus declines with agePrion protein in human hippocampus declines with age
Whitehouse et al. (2010) J. Alz. Dis. 22, 1023-1031
PrPPrPCC facilitates neuronal facilitates neuronal zinc zinc uptake via AMPA receptorsuptake via AMPA receptors
PrPC
Actin
siRNA - +
30
43
Zn
Zn + siRNA0.4
0.6
0.8
1
1.2
Rat hippocampal neurons
Ne
wp
ort
gre
en
flu
ore
sce
nce (
rela
tive
in
cre
ase
)
New
port
gre
en f
luore
scence
(Rela
tive incre
ase)
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15 20 25 30
Time (min)
Zn + CNQX
Zn
Zn + siRNA
Watt et al. (2012) Nat. Commun. 3:1134
Time (min)
Zn + siRNA
0.2
0.4
05 10 15 20 25 30
Ne
wp
ort
gre
en
flu
ore
sce
nce (
rela
tive
PrPC siRNAPrPC
Newport green staining
Time (min)
New
port
gre
en f
luore
scence
(Rela
tive incre
ase)
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15 20 25 30
Zn
Zn + IEM-1460
GluA2-lacking, Ca2+ and Zn2+
permeable AMPAR
Potential mechanism Potential mechanism by which by which prion protein facilitates zinc prion protein facilitates zinc uptake into uptake into cells through the AMPA receptorcells through the AMPA receptor
Probe: GluA1
Probe: GluA2
Probe: PrPC
kDa
100
90
30
B
Watt et al. (2012) Nat. Commun. 3:1134 Watt et al. (2013) Prion 7, 203-208
Protein tyrosine phosphatase
A
0
100
200
300
400
500
600
700
800
900
WT PrP-/-
pM
PO
4-re
lease/µ
g/m
in
0
50
100
150
200
250
300
Un PrPC
B
**
*
pM
PO
4-re
lease/µ
g/m
in
SH-SY5Y cells PrP null mice
AβAβ oligomers
Neuronal death
Alzheimer’s Disease
IImpact of reduced prion protein on zinc metabolism in mpact of reduced prion protein on zinc metabolism in sporadic Alzheimer’s disease and ageingsporadic Alzheimer’s disease and ageing
23
3) � binding of Aβ oligomers to PrPC further � zinc uptake
2) � extracellular Zn promotes Aβ oligomer formation and neurotoxicity
1) � intracellular protein tyrosine phosphatase activity leading to neurotoxicity
Zn
Normal
PrPc
� Protein tyrosine phosphatase
Toxicity
Neuronal death and dysfunction
3
1
Zn
AMPA receptor
� Protein tyrosine phosphatase
Prion protein in Alzheimer’s diseasePrion protein in Alzheimer’s disease-- neuroprotectiveneuroprotective, neurotoxic or both!, neurotoxic or both!
Benilova & De Strooper(2010) EMBO Mol. Med. 2, 289
PrPPrPCC forms multiple cell surface, raftforms multiple cell surface, raft--based complexesbased complexes
Watt et al. (2014) Frontiers Cell Develop. Biol. 2
EGCG and resveratrol EGCG and resveratrol reduce the cellular binding of Areduce the cellular binding of Aββoligomers and their downstream cytotoxicity oligomers and their downstream cytotoxicity
EGCG [(-)-epigallocatechin
gallate]
Resveratrol
Rushworth et al. (2013) J. Biol. Chem. 288, 8935
PPrion rion protein protein as a therapeutic target in Alzheimer’s diseaseas a therapeutic target in Alzheimer’s disease-- issues issues to to considerconsider
� Targeting disease vs normal functions of PrPC
� Receptors other than PrPC
� Type (“strains”) and concentration of Aβ oligomer
“Rather than exist as separate entities, several of these candidate receptor molecules may be closely linked in a multi-protein receptor complex, whose specific members may change as a result of electrophysiological activity or damage.”Susan Catalano, Alzforum
Benilova & DeStrooper (2013) Science 341, 1354
AcknowledgementsAcknowledgements
Hooper Lab
Rob AndrewHeledd GriffithsKate KellettBeth Noble
Lizzie Glennon (Kings, London)Ed Parkin (Lancaster)Jo Rushworth (Leicester)
Bristol
Seth LovePat KehoeScott Miners
Edinburgh
Jean Manson
Vicki Lewis (Melbourne)Emma Vardy (Newcastle)Nicole Watt (Leeds)Isobel Whitehouse (Leeds)
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