Plasma expression levels of microRNA-101 are downregulated in patients with Parkinson’s disease

Objective Parkinson’s disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons. Endoplasmic reticulum (ER) stress contributes to PD pathogenesis, with the ER-associated degradation (ERAD) system playing a protective role. HRD1, an ER-resident ubiquitin ligase, and its stabilizer SEL1L are involved in ERAD and neuronal survival. This study investigated alterations in the plasma levels of microRNA-101 (miR-101), which targets SEL1L, in patients with PD, and its potential role as a biomarker. Results Plasma miR-101 levels in patients with PD significantly decreased compared with those in healthy controls. Receiver operating characteristic curve analysis demonstrated that miR-101 could moderately discriminate patients with PD from healthy individuals (area under the curve = 0.781, 95% confidence interval = 0.547–1.00). The optimal cutoff, as determined by the Youden index, was 0.737 (expression ratio relative to that in the healthy control group), yielding a sensitivity of 50% and specificity of 100%. These results suggested that reduced plasma miR-101 expression may reflect the pathophysiological state of PD, and miR-101 has potential as minimally invasive biomarker for PD.