Dynamic alternative splicing events in the dorsolateral prefrontal cortex during adolescence-young adulthood period and implications for schizophrenia

Alternative splicing (AS) or differential exon usage (DEU) is a regular process after gene expression and it contributes to the diversity of the genome by generating multiple protein isoforms. According to recent studies, the majority (92-94%) of all human multi-exon genes undergo AS and the brain, especially the neocortex, has the highest number of AS events compared to other tissues. While contributing to the complexity of the brain, AS may lead to neuropsychiatric disorders such as schizophrenia or autism if dysregulated. Adolescence and young adulthood (AYA) period which nearly covers age range between 15 to 24 years old, is known to be a critical time to develop several neuropsychiatric disorders including schizophrenia and depression. Therefore, it is important to know developmental changes in AS events that occur in healthy brains in order to understand what is disrupted in a diseased brain. Although there are many studies investigating the possible roles of AS in the function of specific neuron types and during neurogenesis, there are only a few studies investigating AS changes in the human brain during different developmental periods. Therefore, in this study we first compared DEU that occur in the dorsolateral prefrontal cortex (DLPFC) of psychologically healthy individuals during AYA period to other developmental periods: infancy, early childhood, middle and late childhood, young adulthood, middle adulthood, and late adulthood. Additionally we compared DEU that occur in the DLPFC of schizophrenia patients to psychologically healthy individuals. Then we found exons that show both developmental and schizophrenia related DEU changes. Our results revealed 4 exons that belong to 3 different genes: AKAP7, BAIAP3 and SEMA3B. If further investigated, these exons can help us better understand the pathophysiology of schizophrenia and be possible early markers of the disease.