Primary cilia formation is diminished in schizophrenia and bipolar disorder: A possible marker for these psychiatric diseases.

Primary cilium (PC) is a microtubule-rich organelle that protrudes from the plasma membrane and acts as a cellular antenna sensing extracellular signals during brain development. DISC1 (Disrupted-in-Schizophrenia-1) is involved in PC formation and is considered a risk factor for neuropsychiatric disorders. We have previously described altered subcellular distribution of DISC1 and an aberrant microtubule organization in olfactory neuronal precursors (ONP) obtained from schizophrenia (SCZ) and bipolar disorder (BD) patients. Herein, we analyzed in vitro PC formation in healthy control subjects, SCZ and BD patients. The results indicated that 66.73±4.33% of ONP from control subjects showed immunostaining for the PC marker, acetylated α-tubulin. By contrast, only a small percentage of cells in culture from paranoid SCZ and BD patients showed PC staining (SCZ, 12.8±4.43%; BD, 12.32±5.86%). However, cells from an affected proband with disorganized SCZ and a subject with BD displayed a higher percentage of cells with cilia (SCZ, 42.20%; BD, 38.59%). Additionally, cilia elongation was observed in lithium-treated ONP derived from all groups, with a more evident response in cells from the BD group. The present study provides novel evidence that the molecular pathways involved in PC formation are defective in SCZ and BD, and impairment in these processes may be involved in the physiopathology of both diseases. Our observations also suggest that ONP is a patient-derived cell model with a potential use for diagnosis and high-throughput drug screening for brain diseases.