Protein Phosphatase 3 Calcineurin Gamma Isoform Catalytic

1
Protein Phosphatase 3 Calcineurin Gamma Isoform
Catalytic Subunit (PPP3CC) and Schizophrenia An
Association
Akochi O. Agunwamba1, Kimberly Aldinger2,3, and
Pamela Sklar M.D., Ph.D3,4,5 1University of
Massachusetts, Boston, MA, U.S.A 2Harvard
University, Cambridge, MA, U.S.A 3Broad
Institute, Cambridge, MA, USA 4Department of
Psychiatry, Harvard Medical School, Cambridge,
MA, U.S.A and 5Psychiatric and Neurodevelopment
Genetics Unit, Massachusetts General Hospital,
Charlestown, MA, USA
Discussion
Result summary continued
PPP3CC is critical in calcineurin structure
Abstract
The calcineurin protein phosphatase gamma
catalytic subunit gene, PPP3CC, was previously
reported to be associated with schizophrenia. We
sought to confirm this association in an
independent Portuguese schizophrenia sample. We
genotyped four of the five previously reported
SNPs of PPP3CC to uniquely identify each of the
haplotypes and did not obtain a significant
result.  However, extending this haplotype with
two additional htSNPs selected from the HapMap,
we identified a significant haplotype (p 0.037)
lending support to the initial finding.

• Statistics for significant haplotype
• Frequency in combined sample 41
• Transmitted/non-Transmitted 1.26
• Transmission Distortion Test (TDT) p-value
  0.00124
• significant signal on the PPP3CC locus
• NOTE p-value lt 0.05 ? significant positive
  association

• We had similar results for major haplotype to
  that of Gerber et al on the same PPP3CC locus
• In both cases, the major haplotype was the most
  significant and the frequencies are equivalent
• A sub-haplotype may be responsible for the
  significant signal reported by Gerber et al
• The haplotype may be a common allele of small
  effect

PPP3CC catalytic subunit
Acknowledgements
We sought to replicate Gerbers study
We, would like to thank the following who were
instrumental to the success of this project
Broad Institute of MIT and Harvard, Minority
Summer Research Program in Genomics, Skye
Waggoner, Anthony Tahl, Jinbo Fan PhD, Tracey
Petryshen, PhD, Emily Walsh PhD, Angela Brunache,
Jennifer Meade, Roy Charles Contact information
Emailakochi_at_cs.umb.edu Phone[phone] Webww
w.cs.umb.edu/akochi/research/summer2004_broad_mit
/

• Re-characterize variation in PPP3CC locus
• Verify Gerber association

Our Motivation Why is this important?

• Schizophrenia is a devastating brain
  disorderthe most chronic and disabling of the
  severe mental illnesses.1
• It affects 1 of people in every population
  studied1,4,6
• It is non-mendelian ? data replication is needed
  but difficult2
• Strong association results may lead to better
  therapies3
• Currently, Schizophrenia (SCZ) has no cure!

Our Method

• Sample
• Portuguese, 111 trios, 321 Cases, 242
  Controls
• Selected SNPs
• The Gerber SNPs and two HapMap SNPs7,8
• Genotyping
• Polymerase chain reaction, clean-up with Shrimp
  alkaline phosphatase, homogenous mass- extension
  step, typing with Matrix-assisted laser
  desorption ionization-time of flight (MALDI-TOF)
  process
• Analysis
• TDT, 22 Chi sq. contingency table significance
  test

PPP3CC gene Found in susceptibility locus

• Other susceptibility gene candidates in the
  locus
• Early Growth Response Factor expressed in
  neurons and involved in ataxia4,6
• Neuregulin involved in expression and
  activation of neurotransmitter receptors4

Calcineurins Functional Link with SCZ
References
Gerber et al find PPP3CC-SCZ association

• http//www.nimh.nih.gov/publicat/schizsoms.cfm
• Bray N.J. and Owen M.J. (2001) Trends Mol Med.
  7(4)169-74.
• Svenningsson, P., Nomikos G. G., and Greengard,
  P. (2004) Science 305 (5681) 180d - 180d.
• Gerber, D. J. Hall, D. Miyakawa, T. Demars,
  S. Gogos, J. A. Karayiorgou, M. Tonegawa, S.
  (2003) Proc. Nat. Acad. Sci. 100 8993-8998.
• Miyakawa, T. Leiter, L. M. Gerber, D. J.
  Gainetdinov, R. R. Sotnikova, T. D. Zeng, H.
  Caron, M. G. Tonegawa, S. (2003) Proc. Nat.
  Acad. Sci. 100 8987-8992.
• Tourtellotte W.G. and Milbrandt J. (1998) Nat.
  Gen. 20, 87-91
• http//www.hapmap.org
• http//www.cephb.fr/
• http//www.ornl.gov/sci/techresources/Human_Genome
  /publicat/hgn/v12n1/13trinity.shtml
• http//www.jneurosci.org/cgi/content/full/17/21/8
  147/F8

• Mice lacking calcineurin regulatory protein
  showed SCZ-like symptoms5
• PPP3CC (on 8p21.3), a calcineurin catalytic
  protein shows association with SCZ in a study by
  Gerber et al.4

Our Results

• H_SNP1 H_SNP2
• G_SNP1 G_SNP2 G_SNP3 G_SNP4
• PPP3CC
• Locus
• (8p21.3)
• TDT
• Freq p-value
• Gerber Haplotype 41 C - T - G
  A 0.00124
• Sub haplotype 39 C A T C G
  A 0.037
• KEY G_SNPx SNP from Gerber et al. study
• H_SNPx SNP from HapMap database

Result summary of Gerber et als study

• Sample
• - US sub-sample 210 trios
• - South African Afrikaans sub-sample 200 trios
• PPP3CC haplotype with significant association
• G_SNP1 G_SNP2 G_SNP3 G_SNP4
• PPP3CC
• Locus ? - - ---C-------------T-------------G---
  --------A--- - -
• (8p21.3)
• KEY G_SNPx SNP from the Gerber et al. study

• Studies indicate that calcineurin is needed for
• Ca2 dependent dopaminergic and NMDA signaling4
• endocytosis of clathrin-mediated synaptic
  vesicles4
• serotonin-dependent and ITPR1 Ca2 regulation4
• Conjecture
• Calcineurin may be involved in a pathway that
  links dopaminergic and glutamatergic neural
  signaling systems