Dysregulation of DPYSL2 expression by mTOR signaling in schizophrenia: Multi-level study of postmortem brain

The mechanistic target of rapamycin (mTOR)-signaling and dihydropyrimidinase-like 2 (DPYSL2), which are increasingly gaining attention as potential therapeutic targets for schizophrenia, are connected via Cap-dependent translation of the 5'TOP motif. We quantified the expression of molecules constituting the mTOR-signaling and DPYSL2 in the prefrontal cortex (PFC) and superior temporal gyrus (STG) of postmortem brain tissue samples from 24 patients with schizophrenia and 32 control individuals and conducted association analysis to examine abnormal regulation of DPYSL2 expression by the mTOR-signaling in schizophrenia. The average ribosomal protein S6 (S6) levels in the PFC and STG were lower in patients with schizophrenia (p < 0.01). DPYSL2 expression showed a significant positive correlation with phospho-S6 expression levels, which were effectors of mTOR translational regulation, and the correlation slope between phospho-S6 and DPYSL2 expressions differed between cases and controls. Association analyses of these mTOR-signaling and DPYSL2 alterations with genetic polymorphisms and the clinical profile suggested that certain genetic variants of DPYSL2 require high mTOR-signaling activity. Thus, the findings confirmed decreased S6 expression levels in schizophrenia and supported the relationship between the mTOR-signaling and DPYSL2 via 5'TOP Cap-dependent translation, thus providing insights connecting the two major schizophrenia treatment strategies associated with the mTOR-signaling and DPYSL2.