the amyloid hypothesis of alzheimer pathogenesis app amyloid- production self-assembly clinical ad...
TRANSCRIPT
The Amyloid Hypothesis of Alzheimer Pathogenesis
APP
Amyloid-production
Self-assembly
clinical ADneuronal cell death
tautau
SWAN Proteins Wong & Wu
APP: Chromosomal Location
APP Genetic locus on Chr. 21q21.3
APP is a single copy gene. It exists as one copy per haploid genome.
SWAN Proteins Wong & Wu
APP is a gene that encodes a complexity of proteins
• A single locus: single copy per haploid genome• Multiple splice variant mRNAs• Multiple protein isoforms expressed
– Some isoforms are ubiquitous, others neuron specific or T cell-specific
• Variety of conserved functional domains throughout length of protein
– Isoform differences in major domains• APP interacts with multiple proteins• Mutations throughout protein associated with familial Alzheimer
Disease• Cleavage products generated by α-, β- and γ-secretase are
involved in both normal and pathogenic protein processing.
SWAN Proteins Wong & Wu
APP Gene encodes 10 Isoforms produced by Alternative Splice Variants
There are three major isoforms:
There are seven and probably more additional isoforms.
SWAN Proteins Wong & Wu
Isoform Hep Zn+/Cu+ Kunitz Hep Hep Hep β α γ Goα Casp
Isoform APP770 P05067-1 + + + + + + + + + + +Isoform APP751 P05067-8 + + + + + + + + + + +Isoform APP695 P05067-4 + + + + + + + + +Isoform L-APP677 P05067-3 + + + + + + + + + +Isoform L-APP696 P05067-5 + + + + + + + + + +Isoform L-APP733 P05067-7 + + + + + + + + + + +Isoform APP714 P05067-6 + + + + + + + + + +Isoform APP305 P05067-2 + +Isoform L-APP752 P05067-9 + + + + + + + + + + +Isoform APP639 P05067-10 + + + + + + + + + +
TMKunitzHep
Zn+/Cu+
Hep Hep Goα
Caspase
Conserved Functional Protein Domains in APP Suggest Functional Differences between Protein Isoforms
SWAN Proteins Wong & Wu
APP does more than produce Aβ…
but production of Aβ is the critical step for AD.
SWAN Proteins Wong & Wu
Intracellular Processing of APP Generates a Variety of Cleavage
Products APP is Cleaved into the following 12 chains: 1- Soluble APP-α 2- Soluble APP-β 3- C99 4- Beta-amyloid protein 42 5- Beta-amyloid protein 40 6- C83 7- P3(42): α-secretase and γ-secretase product 8- P3(40): α-secretase and γ-secretase product 9- Gamma-secretase C-terminal fragment 59 Alternative name(s): γ-CTF(59) Amyloid intracellular domain 59 Short name=AICD-59 or AID(59) 10- Gamma-secretase C-terminal fragment 57 Alternative name(s): γ-CTF(57) Amyloid intracellular domain 57 Short name=AICD-57 or AID(57) 11- Gamma-secretase C-terminal fragment 50 Alternative name(s): γ-CTF(50) Amyloid intracellular domain 50 Short name=AICD-50 or AID(50) 12- C31
http://journals.prous.com/journals/dnp/20061907/html/dn190411/images/fig1.gif
SWAN Proteins Wong & Wu
Intracellular APP trafficking
SWAN Proteins Wong & Wu
APP interacts with many proteins
http://string.embl.de/newstring_cgi/show_network_section.pl?taskId=TuwI5V8me0SR&use_java=no&network_flavor=evidence
APP Binds
UniProt APP Binds
UniProt
APBA1 Q02410 HSD17B10 Q99714
APBB1 O00213 MAPK8IP1
Q9UQF2
Apbb1 P46933 Mapk8ip1 Q9WVI9-1
APBB2 Q92870 MAPT P10636
Apbb3 O35827 MAPT P10636-8
APLP1 P51693 PRNP P04156
APLP2 Q06481 PSEN1 P49768
APOA1 P02647 PSEN2 P49810
CHRNA7 P36544 SHC1 P29353
Chrna7 Q05941 SHC3 Q92529
CNTN3 Q9P232 Slc5a7 Q8BGY9
CNTN4 Q8IWV2 TGFB1 P011371
FLOT1 O75955 TGFB2 P61812
HOMER2 Q9NSB8 TP53BP2 Q13625
HOMER3 Q9NSC5
APP
Amyloid- (A40 vs A42)
Amyloid Plaques
Genetic Mutations in the Gene for APP Can Cause Alzheimer’s Disease
-Secretase: Carries out the first cut that produces the N-terminus of A
Wolfe. Sci. Am., 2006
Co-crystal structure of Co-crystal structure of -secretase with an inhibitor:-secretase with an inhibitor:coordination of hydroxyl group with the catalytic aspartatescoordination of hydroxyl group with the catalytic aspartates
Hong et al. Science, 2000, 290, 150-3
BACE1 splice isoformsAlternative splicing within exons 3 and 4
BACE2Homolog of BACE1; also cleaves APP.
BACE1 substratesAPP, neuregulin, ST6Gal 1, Nav1 2, others
Processing of BACE1Signal sequence and prodomain removal, glycosylation
Intracellular localization of BACE1ER, Golgi, cell surface, endosomes
Tissue distribution of BACE1Ubiquitous but most highly in the brain
The Complexities of -Secretase (-site APP cleaving enzyme; BACE1)
-SecretasesMetalloproteases ADAM-10, -17, and -9
Where they cut within APPWithin the A sequence, thereby precluding A formation
How they are regulatedADAM-10 is constitutive, while ADAM-17 is inducible
Why they may be important therapeuticallyActivity can be stimulated by agonists for certain muscarinic receptor subtypes
The Complexities of -Secretase
Other substratesThese are major sheddases; many other membrane protein substrates
-Secretase: Performs the second cut that produces the C-terminus of A
Wolfe. Sci. Am., 2006
DD
lumen/extracellular
cytosol
Presenilin
OH
PhO
NH
Ph
NH NHO Ph
O
NH-Bt
O
O
HN N
H
HN N
HOBt
O
OH O
OF FBr
O
NTF CTF
A
AICD
APP
Wolfe et al. Nature 1999, 398, 513.Li et al. Nature 2000, 405, 689.Esler et al. Nature Cell Biology 2000, 2, 428.
p3/A
C83/C99
p6
Nicastrin,other
factors
PS1
1 2
3
Proposed Mechanism of -Secretase
Esler et al. PNAS, 2002, 99, 2720-7
2003
2001
1999
1997
SREBP Reg
S1P
S2P
lumen/extracellular
cytosol
S2P
SPP
SP
lumen/extracellular
cytosol
sig
na
l pep
tid
e
SPP
S4
S2,
DD
lumen/extracellular
cytosol
Aph-1 NCT
CTF
NTF
Pen-2
Presenilin
S3,
Spitz
RhomboidS H
lumen/extracellular
cytosol
Rhomboid
Wolfe and Kopan. Science 2004
DD
HE
XX
H
LD
G
Aph-1
NCT
NTF
Pen-2
-Secretase: A Complex and Unusual Protease
Takasugi et al. Nature 2003Kimberly et al. PNAS 2003Edbauer et al. Nat Cell Biol 20031:1:1:1 Stoichiometry: Sato et al. JBC 2007
CTF
The size of the -secretase complex is ~230 kDa by scanning transmission electron microscopy
Osenkowski et al. JMB 2009.
CryoEM Structure of -Secretase
Osenkowski et al. JMB 2009.
PS mutationsOver 100 FAD-associated mutations
PS1 vs PS2PS1 is the major player, both in AD and biology
Aph1 isoformsAph1- and Aph1-ph1- and Aph1-2
Nicastrin glycosylation16 glycosylation sites that occur in transit from the ER
Other processing events at PSCaspase cleavage gives short CTF
Intracellular localizationER, Golgi, cell surface, endosomes, mitochondria
The Complexities of -Secretase
S4
S2
DD
lumen/extracellular
cytosol
Presenilin
S3
NTF CTF
Np3
NICD
Notch
DeStrooper et al. Nature 1999, 398, 518.
AP
P
AICD
A48/49
A45/46 A42/43
’
A38/40
Ihara Model of Processive Proteolysis of APP
When Tau Goes Bad
Wolfe. Sci. Am., 2006
SWAN Proteins Wong
Tau: Chromosomal LocationMAPT Genetic locus on Chr. 17q21.1
WT: MAPT is a single copy gene. It exists as one copy per haploid genome. Disease: MAPT gene mutations have been associated with several neurodegenerative disorders such as Alzheimer's disease, Pick's disease, frontotemporal dementia, cortico-basal degeneration and progressive supranuclear palsy.
Source: MAPT Mapviewer (NCBI)
SWAN Proteins Wong
Tau is a gene that encodes a complexity of proteins
• A single locus: single copy per haploid genome
• Multiple splice variant mRNAs
• Mulitiple protein isoforms expressed– tau is not only present in neurons but is also clearly present in
oligodendroglia and astrocytes
• Variety of conserved functional domains throughout length of protein
– Isoform differences in major domains
• Tau interacts with multiple proteins
• ~40 FTDP-associated mutations
Alternative Splicing of Tau in FTDP-17
Wolfe. JBC 2009
Stem Loop Structure and Exon 10 Splicing
Wolfe. JBC 2009
SWAN Proteins Wong
Tau protein is highly phosphorylated: Phosphorylation state appears to be critical to disease
Acknowledgments
Funding
National Institutes of HealthAlzheimer’s Association
ISOA/ADDF
Wolfe Lab
ProteasesWilliam EslerTaylor KimberlyChittaranjan DasFrédéric BihelAnna KornilovaPatrick FraeringPam OsenkowskiToru SatoSarav NarayananOmar Quintero-MonzonMorgan MartinMarty Fernandez
RNAChristine DonahueYang LiuEleanor PeaceyKaren MowrerJean-François Fisette
Collaborators
ProteasesDennis SelkoeRafi Kopan
Bart De StrooperTodd Golde
Huilin Li
RNAKen KosikJane Wu
Eriks RosnersMarcie GlicksmanGabriele Varani
LEAD
Corinne Augelli-SzafranHan-Xu Wei
Dai LuJing ZhangYongli Gu