Biology subjects

Levy, O. A.

Publications and source records attributed to Levy, O. A..

2 recordsLinked to original sources

bioRxiv2025

A Dual Assay to Compare Protein Levels and Toxicity of Alpha-Synuclein Variants: Acute Expression of Wild-Type versus S129A

Parkinsons disease (PD) affects over 12 million people worldwide and has the fastest-growing global impact. The pathological hallmark is the presence of Lewy bodies and Lewy neurites, which are intraneuronal lesions enriched in aggregated alpha-synuclein (S) that is typically hyper-phosphorylated at serine 129. Therefore, lowering phosphoserine 129 (pS129) may be a viable therapeutic strategy to treat PD. However, pS129 has also been proposed to regulate synaptic transmission and S degradation. In both cases, inhibiting pS129 could be detrimental. Here, we developed a sensitive assay in a human neuroblastoma model and utilized it to assess the relative expression levels and cytotoxicity of pS129 by comparing S wild-type (WT) vs. S129A (pS129-deficient). We show that the S129A mutant does not affect the acute expression levels or toxicity of S in a transient transfection paradigm. This provides new insight into the intricate interplay between S, phosphorylation, toxicity, and degradation. Our assay provides a versatile platform for understanding disease-relevant mechanisms and opens novel avenues for the design of future therapeutic interventions in PD and other -synucleinopathies.

cell biology↗

bioRxiv2018

Stress-induced phospho-ubiquitin formation causes parkin degradation

Mutations in the E3 ubiquitin ligase parkin are the most common known cause of autosomal recessive parkinsonism. Multiple types of stress decrease parkin protein levels, an effect that may be relevant to sporadic Parkinsons disease (PD), but the mechanism(s) involved in this loss remain largely unclear. We sought to elucidate these mechanisms using a PD-relevant stressor, L-DOPA, the precursor to dopamine, which forms reactive oxygen species (ROS) as well as toxic quinones via auto-oxidation. We find that L-DOPA causes parkin loss through both an oxidative stress-independent and an oxidative stress-dependent pathway. Characterization of the latter reveals that it requires both the kinase PINK1 and parkins interaction with phosphorylated ubiquitin (phospho-Ub) and is mediated by proteasomal degradation.\n\nSurprisingly, mitochondrial parkin activity and autoubiquitination as well as mitophagy are not required for such loss. During stress induced by the oxidative stressor hydrogen peroxide or the metabolic uncoupler CCCP, parkin degradation also requires its association with phospho-Ub, indicating that this mechanism is broadly generalizable. As oxidative stress, metabolic dysfunction and phospho-Ub levels are all elevated in PD patients, we suggest that these changes may lead to the loss of parkin expression in PD.

molecular biology↗