Abstract
MicroRNAs (miRNAs) have been investigated in neurodevelopmental and psychiatric disorders including schizophrenia (SZ). Previous studies showed miRNAs dysregulation in postmortem brain tissues and peripheral blood of SZ patients. These suggest that miRNAs may play a role in the pathophysiology of SZ and be a potential biomarker of SZ. Previous studies also showed that miRNAs regulated neurogenesis and that neurogenesis was involved in the pathophysiology of SZ. In addition, a recent study showed that miR-19a and 19b, enriched in neural progenitor cells (NPC) in adult hippocampus, were increased in human NPC derived from induced pluripotent stem cell derived from SZ patients. However, it remains unclear whether the levels of miR-19a and 19b are altered in peripheral blood of SZ patients and how miR-19a and 19b affects neurogenesis. To elucidate them, first we examined the levels of miR-19a and 19b in peripheral blood of SZ patients with quantitative RT-PCR and showed that the level of miR-19b, but not miR-19a, was significantly higher (miR-19a: p = 0.5733, miR-19b: p = 0.0038) in peripheral blood of SZ patients (N = 22) than that of healthy controls (N = 19). Next, we examined the involvement of miR-19b in proliferation and survival of mouse neonatal mice hippocampus-derived NPC with BrdU assay and TUNEL assay. The silencing of miR-19b significantly increased proliferation (N = 5, p = 0.0139), but not survival (N = 5, p = 0.9571), of neonatal mice hippocampus-derived NPC. These results suggest that the level of miR-19b in peripheral blood is a potential biomarker of schizophrenia and that the higher level of miR-19b may increase the vulnerability of SZ via attenuating proliferation of hippocampal NPC.