A number of studies suggest that schizophrenia (SZ) is caused by a deficiency in glutamatergic transmission. The analysis of glutamatergic pathways in SZ has been addressed using a variety of different experimental approaches, one of which is gene expression profiling using array hybridization carried out with postmortem brain tissue or peripheral blood leukocytes. These studies have provided many exciting clues to SZ pathogenesis. However, there are glaring limitations when leukocytes are used as a surrogate for gene expression in the brain, and many confounding factors make it difficult to interpret data from autopsy specimens. In addition, these sources of biological material cannot be used for electrophysiological analysis. Consequently, the ability to study molecular and electrophysiological events in cultivated patient-specific glutamatergic neurons would greatly enhance our understanding of underlying disease mechanisms. The discovery of induced pluripotent stem (iPS) cells, and the prospect of driving them to differentiate into glia, oligodendrocytes, and various neuronal subtypes, provides the opportunity to address the problems associated with interpreting data from postmortem tissue. We will generate iPS cells from hair root keratinocytes obtained from control subjects and patients with SZ. The patient cohort will include individuals with SZ who have 22q11 deletions, a genetically homogenous subgroup. Induced pluripotent stem cells will be driven to differentiate into glutamatergic pyramidal neurons using a protocol established in mouse ES cells, and expression profiling will be carried out using massively parallel deep sequencing (RNA-seq), which is more sensitive than array hybridization-based methods. Expression profiles between patients and controls will be compared to identify SZ-specific differences. Since the differentiation protocol being used generates glutamatertic pyramidal neurons capable of forming synaptic connections, electrophysiological analyses will be carried out as well. The proposed experiments using differentiating, patient-specific iPS cells will result in the development of a new method for studying the underlying molecular basis of schizophrenia.
This study describes our interest in growing neurons from patients with schizophrenia. The neurons will be generated from so-called induced pluripotent stem cells, which are derived from skin or hair roots. Induced pluripotent cells have the capacity to develop into many different cell types, including neurons. Studying neurons from patients with schizophrenia will contribute to our understanding of this enigmatic illness and possibly lead to new therapies.
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