Search bioRxiv⌕ Search

Biology subjects

Sinisgalli, C.

Publications and source records attributed to Sinisgalli, C..

2 recordsLinked to original sources

Parkinson disease-associated protein DJ-1 regulates the autophagic-lysosomal pathway through ROS-dependent modulation of the AMPK/mTORC1 axis.

Mutations in the protein DJ-1 are linked to familial forms of Parkinsons disease (PD). The protein has been well-documented to exert a role in energy metabolism and antioxidant defense, contributing to the maintenance of mitochondrial homeostasis. We and others have previously observed that DJ-1 can also influence autophagy, but the mechanisms are still incompletely defined. In this study, using complementary cellular and animal models, we characterize the impact of DJ-1 loss on the autophagic pathway. Our data demonstrate that DJ-1 deficiency impairs autophagosome-lysosome fusion and lysosomal degradation, resulting in the accumulation of dysfunctional autolysosomes and the subsequent buildup of autophagic substrates. Mechanistically, we show that elevated reactive oxygen species (ROS) in DJ-1-null models inhibit the energy-sensing AMP-activated protein kinase (AMPK), thereby activating the autophagy suppressor mechanistic target of rapamycin 1 (mTORC1). Collectively, these findings delineate a novel signaling axis linking oxidative stress to autophagic dysfunction, providing new insights into the cellular mechanisms underlying autophagic dysfunction in PD.

cell biology↗

Identification and characterization of nanobodies acting as molecular chaperones for glucocerebrosidase through a novel allosteric mechanism

The enzyme glucocerebrosidase (GCase) catalyses the hydrolysis of glucosylceramide to glucose and ceramide within lysosomes. Homozygous or compound heterozygous mutations in the GCase-sencoding GBA1 gene cause the lysosomal storage disorder Gaucher disease, while heterozygous mutations are the most frequent genetic risk factor for Parkinsons disease. These mutations commonly affect GCase stability, trafficking or activity. Here, we report the development and characterization of nanobodies (Nbs) targeting and acting as chaperones for GCase. We identified several Nb families that bind with nanomolar affinity to GCase. Based on biochemical characterization, we grouped the Nbs in two classes: Nbs that improve the activity of the enzyme and Nbs that increase GCase stability in vitro. A selection of the most promising Nbs was shown to improve GCase function in cell models and positively impact the activity of the N370S mutant GCase. These results lay the foundation for the development of new therapeutic routes.

biochemistry↗