Neurodevelopmental defects and neurodegenerative phenotypes in human brain organoids carrying Parkinson’s disease-linked <i>DNAJC6</i> mutations

Abstract

Loss-of-function mutations of <i>DNAJC6</i>, encoding HSP40 auxilin, have recently been identified in patients with early-onset Parkinson's disease (PD). To study the roles of DNAJC6 in PD pathogenesis, we used human embryonic stem cells with CRISPR-Cas9-mediated gene editing. Here, we show that <i>DNAJC6</i> mutations cause key PD pathologic features, i.e., midbrain-type dopamine (mDA) neuron degeneration, pathologic α-synuclein aggregation, increase of intrinsic neuronal firing frequency, and mitochondrial and lysosomal dysfunctions in human midbrain-like organoids (hMLOs). In addition, neurodevelopmental defects were also manifested in hMLOs carrying the mutations. Transcriptomic analyses followed by experimental validation revealed that defects in DNAJC6-mediated endocytosis impair the WNT-LMX1A signal during the mDA neuron development. Furthermore, reduced <i>LMX1A</i> expression during development caused the generation of vulnerable mDA neurons with the pathologic manifestations. These results suggest that the human model of <i>DNAJC6</i>-PD recapitulates disease phenotypes and reveals mechanisms underlying disease pathology, providing a platform for assessing therapeutic interventions.