Search

Objective In the present work, we aimed to investigate the expression of microRNAs (miRNAs) in routine colonic biopsies obtained from patients with idiopathic Parkinson's disease (PD) and to address their value as a diagnostic biomarker for PD and their mechanistic contribution to PD onset and progression. Methods Patients with PD (n = 13) and healthy controls (n = 17) were prospectively recruited to undergo routine colonic biopsies for cancer screening. Total RNA was extracted from the biopsy material and the expression of miRNAs was quantified by Illumina High-Throughput Sequencing. Results Statistical analysis revealed a significant submucosal enrichment of the miRNA hsa-miR-486–5p in colonic biopsies from PD patients compared to the control subjects. The expression of miR-486–5p correlated with age and disease severity as measured by the UPDRS and Hoehn & Yahr scale. miRNA gene target analysis identified 301 gene targets that are affected by miR-486–5p. A follow-up associated target identification and pathway enrichment analysis further determined their role in distinct biological processes in the enteric nervous system (ENS). Interpretation Our work demonstrates an enrichment of submucosal miR-486–5p in routine colonic biopsies from PD patients. Our results will support the examination of miR-486–5p as a PD biomarker and help to understand the significance of the miR-486–5p gene targets for PD onset and progression. In addition, our data will support the investigation of the molecular and cellular mechanisms of GI dysfunction in PD.

Tau is a microtubule-associated protein with versatile functions in the dynamic assembly of the neuronal cytoskeleton. Four-repeat (4R-) tauopathies are a group of neurodegenerative diseases defined by cytoplasmic inclusions predominantly composed of tau protein isoforms with four microtubule-binding domains. Progressive supranuclear palsy, corticobasal degeneration, argyrophilic grain disease or glial globular tauopathy belong to the group of 4R-tauopathies. The present review provides an introduction in the current concept of 4R-tauopathies, including an overview of the neuropathological and clinical spectrum of these diseases. It describes the genetic and environmental etiological factors, as well as the contemporary knowledge about the pathophysiological mechanisms, including post-translational modifications, aggregation and fragmentation of tau, as well as the role of protein degradation mechanisms. Furthermore, current theories about disease propagation are discussed, involving different extracellular tau species and their cellular release and uptake mechanisms. Finally, molecular diagnostic tools for 4R-tauopathies, including tau-PET and fluid biomarkers, and investigational therapeutic strategies are presented. In summary, we report on 4R-tauopathies as overarching disease concept based on a shared pathophysiological concept, and highlight the challenges and opportunities on the way towards a causal therapy.