title: Schizophrenia gene networks and pathways and their applications for novel candidate gene selection.
abstract: BACKGROUND
  Schizophrenia (SZ) is a heritable, complex mental disorder. We have seen limited success in finding causal genes for schizophrenia from numerous conventional studies. Protein interaction network and pathway-based analysis may provide us an alternative and effective approach to investigating the molecular mechanisms of schizophrenia.
  
  
  RESULTS
  We selected a list of schizophrenia candidate genes (SZGenes) using a multi-dimensional evidence-based approach. The global network properties of proteins encoded by these SZGenes were explored in the context of the human protein interactome while local network properties were investigated by comparing SZ-specific and cancer-specific networks that were extracted from the human interactome. Relative to cancer genes, we observed that SZGenes tend to have an intermediate degree and an intermediate efficiency on a perturbation spreading throughout the human interactome. This suggested that schizophrenia might have different pathological mechanisms from cancer even though both are complex diseases. We conducted pathway analysis using Ingenuity System and constructed the first schizophrenia molecular network (SMN) based on protein interaction networks, pathways and literature survey. We identified 24 pathways overrepresented in SZGenes and examined their interactions and crosstalk. We observed that these pathways were related to neurodevelopment, immune system, and retinoic X receptor (RXR). Our examination of SMN revealed that schizophrenia is a dynamic process caused by dysregulation of the multiple pathways. Finally, we applied the network/pathway approach to identify novel candidate genes, some of which could be verified by experiments.
  
  
  CONCLUSIONS
  This study provides the first comprehensive review of the network and pathway characteristics of schizophrenia candidate genes. Our preliminary results suggest that this systems biology approach might prove promising for selection of candidate genes for complex diseases. Our findings have important implications for the molecular mechanisms for schizophrenia and, potentially, other psychiatric disorders.
authors.affiliation: Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.
authors.forename: Jingchun
authors.initials: J
authors.lastname: Sun
authors.forename: Peilin
authors.initials: P
authors.lastname: Jia
authors.forename: Ayman H
authors.initials: AH
authors.lastname: Fanous
authors.forename: Edwin
authors.initials: E
authors.lastname: van den Oord
authors.forename: Xiangning
authors.initials: X
authors.lastname: Chen
authors.forename: Brien P
authors.initials: BP
authors.lastname: Riley
authors.forename: Richard L
authors.initials: RL
authors.lastname: Amdur
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Kendler
authors.forename: Zhongming
authors.initials: Z
authors.lastname: Zhao
mesh_terms: D020022:Genetic Predisposition to Disease; D006801:Humans; D012559:Schizophrenia / Q000235:genetics*