Olfactory neuroepithelial cell derived induced neurons for study of schizophrenia

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PROJECT SUMMARY The pathophysiology of common psychiatric illnesses such as schizophrenia is highly complex and heterogeneous, in which multitudes of common and rare genetic variants and their epigenetic modifications precipitate disease phenotypes. Over the last decade, in vitro modeling of neuropsychiatric illnesses has been led by induced pluripotent stem cell (iPSC) based paradigms. These approaches have a special strength in offering developmental readouts of genetic variations in neurons and organoids. However, the ability to recapitulate complex phenotypes of the illness is hampered because epigenetic characteristics of donors are erased by the stem generation process. The goal of this project is to develop and test directly-converted induced neurons (called DCiNs henceforth) for their ability to manifest neurobiological characteristics of schizophrenia. DCiNs are generated by bypassing the stem cell stage and are thus more likely to harbor epigenetic characteristics of donors. The extent to which DCiNs cells can recapitulate neurobiological phenotypes of donors, however, will vary depending on the epigenetic landscape of the source cells and the methodology for conversion of source cells into neurons. Presently, skin fibroblasts (SFs) are commonly used source cells for iN paradigms, although SFs, as non-neural cells, may not manifest epigenetic characteristics of donors with neuropsychiatric illnesses. We propose using olfactory neuroepithelial (OE) cells, the only neural cells readily obtainable from human subjects, as source cells for DCiNs paradigms. Importantly, the chromatin accessibility of OEs is vastly different from SFs, particularly around neural genes. Among various iN paradigms, we will test a transcriptional modulation-based approach, specifically using a) two transcription factors, ASCL1 and NGN2 (N2A) and b) the transcriptional effector, microRNA (mir) 9/9*-124. We will first characterize the source cells (OE vs. SF), in combination with transcriptional modulators (N2A vs. mir 9/9*- 124), for the ability to differentiate into neurons and recapitulate the epigenetic landscape of donors’ neural cells (Aim 1). As a test of the utility of this paradigm for study of common neuropsychiatric illnesses, we will apply this model to schizophrenia by examining DCiNs-OEs from patients with schizophrenia and controls to delineate the extent to which they recapitulate disease-associated changes (Aim 2). The results of this project will define the extent to which DCiNs -OEs recapitulate neurobiological phenotypes of donors’ and pave the path for establishing the iN paradigms for other neuropsychiatric illnesses.