Centre for Molecular Medicine

1
The DISC1 Pathway in Schizophrenia, Learning,
Memory and Mood

• Centre for Molecular Medicine
• Medical Genetics SectionUniversity of Edinburgh
  Molecular Medicine CentreWestern General
  Hospital Campus
• EDINBURGH

2
THANKS TO..

• COLLABORATORS at Merck Sharp Dohme
• Nick Brandon, Miguel Camargo, Thomas Rosahl, Paul
  Whiting
• COLLABORATORS on PDE4B
• Miles Houslay, Elaine Huston, Elaine Hill, George
  Bailie, Hannah Murdoch, Glasgow
• COLLABORATORS on Disc1 Mouse Models
• Steve Clapcote John Roder, Toronto, Canada
• Yoishi Gondo, RIKEN, Japan
• THE DISC1 CONSORTIUM
• Edinburgh (Hennah, Thomson, Blackwood, Muir
  Porteous)
• Aberdeen (D St Clair), University College London
  (H Gurling),
• Helsinki (L Peltonen)
• SPONSORS
• Medical Research Council
• Wellcome Trust
• Merck Sharp Dohme

• Douglas Blackwood
• Walter Muir
• Kirsty Millar
• Shaun Mackie
• Ben Pickard
• Rachel James
• William Hennah
• Pippa Thomson
• Sheila Christie
• Sebby Cooper
• Fumiaki Ogawa
• Jennifer Chubb

3
The Leading Causes of Disability Worldwide
(Years of Life with Disability)Lopez Murray,
Nature Medicine, 4, 1241-1243 (1998)

• 1. Unipolar depression
• 6. Bipolar Affective Disorder (manic depression)
• 9. Schizophrenia
• 10. Obsessive compulsive disorders
• One in a hundred will develop schizophrenia
• One in a hundred will develop bipolar disorder
• Both conditions are highly heritable
• 10 to 15 fold increased risk in first degree
  relatives
• Higher risk of bipolar if you have a relative
  with schizophrenia and vice versa
• 60-80 concordance in identical twins

4
Schizophrenia positive symptoms of visual
auditory hallucinations, delusions, incoherent
speech
Bipolar Disorder (Manic Depression) manic phase
energetic, grandiose, elated, irritable, reduced
sleep
5
Schizophrenia negative symptoms of withdrawal
isolation, impaired attention blunted emotions
Bipolar Disorder (Manic Depression) despair,
emptiness, inability to experience joy, lack of
energy
6
Psychiatric Genetics

• Clear evidence for major genetic component
• Familial clustering, but no simple patterns of
  inheritance
• Predictions
• Genetic Heterogeneity
• Gene-Gene Interaction
• Gene-Environment Interaction
• Hypotheses
• Common Disease, Common Variant (CDCV)
• Common Disease Rare Variant (CDRV)
• Methods
• Family based linkage
• Population based association
• Candidate genes
• Cytogenetics

7
Major psychosis co-segregating with a balanced
t(111) translocation St Clair et al Lancet
(1990), Blackwood et al AmJHumGenet (2001)
major psychiatric illness (SCZ, BPAD, RMD)
t(111)
minor psychiatric illness (ANX, ALC, MIND)
unaffected
8
The t(111) breakpoint linkage to psychosis
LOD 3.4
MLOD 7.1
11q14
11
1q42
50-fold elevated risk
1
Dominant, variable penetrance, broad diagnosis
9
CHROMOSOME 1 BREAKPOINTMillar et al, Hum. Mol.
Gen, 2000
translocation breakpoint
Novel, 13 exons, 7.5kb mRNA, 854 amino acids,
100kD protein Disrupted in Schizophrenia 1 DISC1
10
DISC1 Association Timeline
Schizoaffective disorder
Major depression
Schizophrenia
Bipolar disorder
2007
1990
2000
2006
2002
2004
Working memory Attention Cognition Gray Matter
Volume
Translocation between chromosomes 1 and 11
associates with SCZ major mental illness
DISC1 Identified at 1q42 Translocation
association with SCZ, BPAD, Major
depression SCZ-like P300 deficit in all t(111)
carriers
11
Linkage Association between DISC1 Psychiatric
Disorder
translocation



SCOTLAND
EUROPE
BRITAIN ICELAND
FINLAND
NORTH-AMERICA
JAPAN
TAIWAN
FINLAND
Leu607Phe
Ser704Cys
SCHIZOPHRENIA
Hennah et al, Scz Bulletin, 2006 Hashimoto et
al, HumMolGen, 2006
SCHIZOAFFECTIVE DISORDER
BIPOLAR AFFECTIVE DISORDER
MAJOR DEPRESSION
Multiple lines of supportive genetic evidence,
but no convergence or validated functional
variants
12
Association between DISC1 Cognition
RAPID VISUAL SEARCH VERBAL WORKING MEMORY
(SCHIZOPHRENIA)
HIPPOCAMPAL STRUCTURE FUNCTION
SPATIAL WORKING MEMORY



NORMAL COGNITIVE AGING
VISUAL WORKING MEMORY (SCHIZOPHRENIA)
VERBAL LEARNING MEMORY
HIPPOCAMPAL VOLUME
GRAY MATTER VOLUME
Leu607Phe
Ser704Cys
13
Biology of DISC1

• Expression
• Interaction
• Biochemistry

14
DISC1 Expression

• Widely expressed
• SCZ associated regions of the brain (hippocampus,
  dentate gyrus)
• peripheral blood lymphocytes / lymphoblastoid
  cell lines
• Developmentally regulated
• Highest during active neurogenesis
• Neonatal adult
• Multiple isoforms
• Multiple cell compartments
• Nucleus
• Centrosome
• Cytoskeleton
• Cytoplasm
• Mitochondria

100
98
80
n-75
71
15
DISC1 Mutiple, Isoform-specific Subcellular
Locations Interactions
16
DISC1 Structure Interacting Proteins
REGIONS OF COILED-COIL FORMING POTENTIAL
S/F-RICH MOTIF
NUCLEAR LOCALISATION SIGNALS

• Yeast 2 Hybrid
• Co-localisation
• Co-immunoprecipitation
• Functional interaction

17
DISC1 interacts with proteins required for
neurodevelopment neuronal function

• NUDE / NUDEL neuronal migration, corticogenesis
  axonal outgrowth
• NUDEL endo oligopeptidase that may regulate
  neuropeptide action in the CNS
• LIS1 lissencephaly 1 (smooth brain), binds
  NUDE/NUDEL
• FEZ1 fasciculation and elongation zeta protein
  1, neurite outgrowth, neuronal differentiation
• PDE4B regulates compartmentalised cAMP signalling

18
Effect of t(111) DISC1 mutation Millar et al.,
Science, 2005
Evidence for DISC1 haploinsufficiency
Prediction reduced interaction with all DISC1
interactors
19
J. Kirsty Millar1, Benjamin S. Pickard1, Shaun
Mackie1, Rachel James1, Sheila Christie1,
Sebastienne R. Buchanan1, M. Pat Malloy1,
Jennifer E. Chubb1, Elaine Huston2, George S.
Baillie2, Elaine V. Hill2, Miles D. Houslay2,
Nicholas J. Brandon3, Jean-Christophe Rain4, L.
Miguel Camargo3, Paul J. Whiting3, Douglas H.R.
Blackwood1,5, Walter J. Muir1,5, David J.
Porteous1.Medical Genetics Section, Molecular
Medicine Centre, University of Edinburgh,
Edinburgh EH4 2XU, UK2Molecular Pharmacology
Group, Division of Biochemistry and Molecular
Biology, IBLS, Wolfson Building, University of
Glasgow, Glasgow G12 8QQ, UK3Merck Sharp and
Dohme, The Neuroscience Research Centre, Terlings
Park, Harlow, Essex, CM20 2QR, UK43HYBRIGENICS
S.A., 3-5 Impasse Reille75014 Paris,
France5Division of Psychiatry, University of
Edinburgh, Royal Edinburgh Hospital, Edinburgh
EH10 5HF, UK
DISC1 and PDE4 Are Interacting Genetic Factors in
Schizophrenia that Regulate cAMP
Signalling Science, 310, 1187-1191 (2005)
Genomics Biology Converge Corroborate
20
PDE4B identified as a DISC1 interactor AND
Psychosis associated t(116) disrupts PDE4B
Millar et al Science 2005

• Proband with SCZ cousin with psychosis

Half normal levels of PDE4B Expression
Haploinsufficiency
PDE4B Association in Schizophrenia Pickard et al,
2007
21
Phosphodiesterase 4B (PDE4B) is very interesting
because

• PDEs are sole means of inactivating
  intracellular cAMP, a key second messenger in the
  brain.
• PDE4 is involved in learning, memory and mood in
  fly mouse.
• PDE4 is target of antidepressant rolipram.

22
The head domain of DISC1 binds the UCR2 domain of
PDE4B Binding is dynamic, cAMP regulated,
phosphorylation dependent and PKA mediated
cAMP
-cAMP
23
PDE4 A, B, C D isoforms
Antidepressant rolipram sensitive
Unique N-termini Sub-cellular targeting cAMP
compartmentalised signalling cAMP gradients
24
DISC1-PDE4 Interaction is Isoform Specific
Murdoch et al, 2007 J Neuroscience, under
revision
UCR2 Catalytic
All
All
B
B
B
100kD
All
All
?
71kD
?
?
N-terminal globular head
C-terminal helical tail
25
DISC1multiple functional motifs interaction
domainsmultiple targets for mutation
modulationmutation class specific effects
26
Limitations of Human Studies of Brain Disorders

• Does modulation / mutation of Mouse Disc1 inform
  on the human conditions of SCZ BPAD?

27
Disc1 RNAi in utero inhibits neuronal migration
in mouse brainKamiya et al Nature Cell Biol 2005
Reduced Migration, Polarity Arborisation
28
Behavioral Phenotypes of Disc1 Missense Mutations
in Mice Clapcote et al, 2007 Neuron, 54, 387-402
29
ENU Missense Mutations in Disc1 Exon2
30
Reduced Brain Volume in Disc1 Mutant Mice
-6 in 31L -13 in 100P
Cerebellum, thalamus, cortex, entorhinal cortex
The Neurodevelopmental Hypothesis in SCZ
31
Mouse Behavioural Tests
Arguello Gogos, Neuron, 2006
32
Pre-Pulse Inhibition (PPI) Latent Inhibition
(LI) Measures of attention, information
processing and working memory

• PPI does a low level stimulus inhibit a startle
  response to a strong stimulus?
• LI can irrelevant stimuli be disregarded and
  memory formation inhibited to prevent information
  overload?
• Both PPI and LI are low in SCZ.
• Both PPI and LI can be measured in the mouse.

33
Pre-Pulse Inhibition is low in 31L and lower
still in 100P Disc1 mutants

• / lt 31L/ lt 31L/31L lt 100P/ lt 100P/100P
  100P/31L

34
Pharmacological Responses in PPI

• 31L rescued by buproprion, but not rolipram
• 100P rescued by rolipram, but not buproprion
• 100P, but not 31L, rescued by clozapine
  (atypical) and haloperidol (dopamine D2
  antagonist)

35
Latent Inhibition is low in 31L and lower still
in 100P Disc1 Mutants
36
The Antipsychotic Clozapine Rescues the Latent
Inhibition Deficit in 100P Disc1 Mutants
37
Open Field Activity100P Disc1 mutants are
hyperactive

• 100P/100P gtgt 100P/ 31L/31L 31L/ /

38
Choice Delay Test of Working Memory100P Disc1
mutants are slower learners
39
Forced Swim Test31L Disc1 mutants show marked
despair

• Despair is rescued by bupropion AND rolipram in
  wild type, but ONLY by bupropion in 31L/31L

40
Summary of Behaviour Drug Responses in 100P
31L Disc1 Mutants

• PPI LI deficits indicate sensory motor gating
  attention deficits
• 100P more severe than 31L
• PPI deficit in 100P partially alleviated by
  typical (haloperidol) atypical (clozapine)
  antipsychotics
• LI deficit in 100P rescued by clozapine
• 31L homozygotes show depressive like behaviour in
  the forced swim test which is reversed by
  bupoprion, but not rolipram

41
Learning, Memory Mood cAMP Signalling PDE4

• Reduced PDE4B activity in 31L, but not 100P

42
DISC1 Missense Mutations PDE4 Binding Domains
UCR2 Catalytic
All
All
B
B
B
Q31L L100P L607F C704S
N-terminal globular head
C-terminal helical tail
43
DISC1 Interactors as Independent Co-dependent
Genetic Risk Factors

• FEZ1
• Association (Yamada et al, 2004)
• PDE4B
• Cytogenetics (Millar et al, 2005)
• Association (Tomppo et al, 2006 Pickard et al,
  2007)
• PDE4D
• Association (Tomppo et al, 2006)
• NUDEL (NDEL1)
• DISC1 ser704cys stratified association
  functional brain imaging (Malhorta et al, 2006)
• NUDE (NDE1)
• DISC1 HEP3 stratified linkage association
  (Hennah et al, 2007)

44
DISC1 Genetic Heterogeneity Genetic Interplay

• Combined analysis of Aberdeen, Edinburgh, London
  Helsinki cohorts
• Finnish SNP and London SNP associate with BPAD
• Stratification on Finnish or London SNP
  identifies a third SNP
• Combined SNPs increase risk of SCZ

1 SNP alone BPAD gtgt SCZ 2 SNPs together
SCZ gt BPAD
45
Conclusions

• The genetic biological evidence supports a
  generalised role for DISC1 in major mental
  illness cognition
• DISC1 is a scaffold protein that assembles
  regulates key neurodevelopmental neurosignaling
  proteins
• Disc1 missense mutants model behavioural,
  pharmacological brain structural features of
  schizophrenia mood disorder
• The DISC1 pathway offers a route towards a
  mechanistic understanding of these poorly
  understood debilitating disorders, prerequisite
  to development of rational interventions

46
Schizophrenia Bipolar Disorder

• One in fifty will develop schizophrenia or
  bipolar disorder
• Current treatment is unsatisfactory
• Major unmet need
• Discovery of DISC1 pathway paves way to
• Molecular basis of disease
• Biomarker discovery
• Diagnosis, prognosis treatment response
• Rational drug development