Understanding the impact of Schizophrenia and Autism risk genes on brain development

1. Understanding the impact of Schizophrenia and Autism risk genes on brain development Karun K. Singh, Ph.D. Stem Cell and Cancer Research Institute Department of Biochemistry and Biomedical Sciences McMaster University

2. ` Genes and Neurodevelopment Brain Development Disorder Normal Brain Development SCHIZOPHRENIA Genetic Mutation AUTISM

3. ` Symptoms of Schizophrenia • Positive symptoms • Hallucinations • Delusions • Thought disorder (confused thinking and speech) • Negative symptoms • Diminished emotional expression • Diminished motivation • Inability to experience pleasure • Cognitive symptoms • Poor concentration • Difficult to plan and organize • Poor memory • Treatments • Antipsychotic drugs (old and new generation) • Cognitive behavior therapy

4. ` Neuropathology of Schizophrenia • Reduction of brain volume (Grey Matter) • Lateral Ventricle enlargement • Decreased GABAergic interneurons (GABA and GAD67 staining) • Less extensive arborization/neuronal complexity (dendritic/synapse) • OVERALL – Nothing absolutely conclusive from brain imaging N Eng J Med. 1990. Unaffected twin Schizophrenic twin

5. ` Genetics plays a major role in psychiatric disorders **Complex genetics at play in psychiatric disorders** (Tom Insel, Director NIMH, JCI, 2010)

6. 2011 Loci for SZ mir137 CSMD1 TRIM26 PCGEM1 Loci for BPD ITIH3-ITIH4 region • Exome Sequencing • Whole Genome Sequencing • …more and more genes!

7. ` Modeling the Genetics of Neurodevelopmental and Psychiatric Disorders Brain Disease Risk Gene Patient Cells Developing Mouse Brain Human Cellular Reprogramming Why do this? Understand how genes impact brain structure/function during development Understand core signaling pathways affected

8. Disrupted in Schizophrenia-1 (DISC1) Chromosome (1; 11) translocation disrupts the DISC1 locus.

10. ` Experimental model to examine DISC1/Dixdc1: The developing mouse cortex Approach: In uteroelectroporation to study neural stem cells and neuronal differentiation/maturation CP - neurons Direction of migration IZ – axon tracts VZ – neural stem cells

11. ` Dixdc1 functionally interacts with DISC1 to regulate neural progenitor proliferation Singh et al., 2010

12. ` Dixdc1 and DISC1 regulate neuronal migration X DISC1 DIXDC1 Frag2 Singh et al., 2010

13. ` Dixdc1 is a critical regulator of DISC1 and embryonic brain development Early brain development Mid-brain development Singh et al., 2010

14. ` Does Dixdc1 functionally interact with DISC1 in neural connectivity development? • Dendrite Growth • Spine Structure • Synapse Formation Penzes et al., Nat Neurosci 2011

15. ` Does a DISC1-Dixdc1 pathway regulate the growth of dendrites and synapses? Control shRNA DISC1 shRNA Dixdc1 shRNA Dixdc1 Frag2 DIV6 Confirming this in vivo  in utero electroporation Vickie Kwan, preliminary results

16. ` Examining synapses with genetic tools: Trans-synaptic labeling using Rabies virus Advantages Single Cell Resolution Watch dynamics over time Ed Callaway Lab Salk Institute

17. ` Trans-synaptic labeling in mouse cortical neurons Culture E17 DIV 10 DIV 14 IUE E15 LV-Syn-HTG Fix cells Infect: Rabies Rabies virus courtesy of Ian Wickersham and Heather Sullivan (SeungLab@MIT) How does DISC/Dixdc1 regulate synapse formation?

18. Studying the Genetics of Autism ` • Not included: • Additional CNVs • Exome sequencing • (de novo mutations) • Whole genome sequencing Aldinger et al., 2011 Neuron

19. Human cellular reprogramming to create patient-derived neural cells ` • Advantages • Model autism genes • Behavior assays • Neural circuits and cell types involved • Some Disadvantages • Difficult to model disease gene networks, large CNVs, human SNPs • Gene disruption doesn’t completely mimic human genetics (eg. KO≠mutation) • Not patient brain tissue (human brain specific)

20. Human cellular reprogramming to create patient-derived neural cells ` Reprogramming genes Differentiate Induced pluripotent stem (iPS) cells Direct conversion Induced Neuronal (iN) or Neural Progenitor (iNP) cells ADVANTAGES of Direct Conversion: Faster than iPS method Epigenetic signature of patient cell is likely preserved Specific Neuronal subtype generation (Spinal Motor, Dopaminergic) Patient-derived NEURAL CELLS patient skin samples

21. Studying the Genetics of Autism ` Aldinger et al., 2011 Neuron

22. Tuberous Sclerosis Complex (TSC): a genetic disorder with high rates of autism ` Collaboration with Dr. Philippe Major, Sainte-Justine Hospital, Montreal Benign tumors in vital organs including brain Autism features (syndromic autism) 25-60% in ASD Learning disabilities, developmental delay Epilepsy • Mouse Models • Protein Translation • Plasticity (mGluR-LTD) Kelleher, III and Bear, 2012 CELL

23. ` Using Cellular Reprogramming to Study TSC and Autism Phenotype and Assay Development Direct Cellular Reprogramming Drug Screen Healthy or TSC Fibroblasts Synapse Function Dendrite/Spine Growth Trans-synaptic labeling Automated Electrophysiology Human Neural Cells

24. In vivo Human Neuronal Model using Xenotransplantation ` Patient-derived neural cells Fluorescent Label • In vivo profile of human cells: • How do patient neural cells functionally integrate into the developing • or adult brain? Transplant

25. Acknowledgements My lab: Vickie Kwan Shashwat Desai Omar Shehab University of Montreal- Sainte Justine Hospital Dr. Philippe Major (TSC) Funding: Ontario Research Fund Massachusetts Institute of Technology: Dr. Li-Huei Tsai