Dataset Information

Chloroquine and bafilomycin A mimic lysosomal storage disorders and impair mTORC1 signalling.

ABSTRACT: Autophagy is dependent upon lysosomes, which fuse with the autophagosome to complete the autophagic process and whose acidic interior permits the activity of their intraluminal degradative enzymes. Chloroquine (CQ) and bafilomycin A1 (BafA) each cause alkalinisation of the lumen and thus impair lysosomal function, although by distinct mechanisms. CQ diffuses into lysosomes and undergoes protonation, while BafA inhibits the ability of the vacuolar type H+-ATPase (v-ATPase) to transfer protons into the lysosome. In the present study, we examine the impact of CQ and BafA on the activity of mammalian target of rapamycin complex 1 (mTORC1), inhibition of which is an early step in promoting autophagy. We find each compound inhibits mTORC1 signalling, without affecting levels of protein components of the mTORC1 signalling pathway. Furthermore, these effects are not related to these agents' capacity to inhibit autophagy or the reduction in amino acid supply from lysosomal proteolysis. Instead, our data indicate that the reduction in mTORC1 signalling appears to be due to the accumulation of lysosomal storage material. However, there are differences in responses to these agents, for instance, in their abilities to up-regulate direct targets of transcription factor EB (TFEB), a substrate of mTORC1 that drives transcription of many lysosomal and autophagy-related genes. Nonetheless, our data imply that widely used agents that alkalinise intralysosomal pH are mimetics of acute lysosomal storage disorders (LSDs) and emphasise the importance of considering the result of CQ and BafA on mTORC1 signalling when interpreting the effects of these agents on cellular physiology.

SUBMITTER: Fedele AO

PROVIDER: S-EPMC7189491 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Chloroquine and bafilomycin A mimic lysosomal storage disorders and impair mTORC1 signalling.

Fedele Anthony O AO Proud Christopher G CG

Bioscience reports 20200401 4

Autophagy is dependent upon lysosomes, which fuse with the autophagosome to complete the autophagic process and whose acidic interior permits the activity of their intraluminal degradative enzymes. Chloroquine (CQ) and bafilomycin A1 (BafA) each cause alkalinisation of the lumen and thus impair lysosomal function, although by distinct mechanisms. CQ diffuses into lysosomes and undergoes protonation, while BafA inhibits the ability of the vacuolar type H+-ATPase (v-ATPase) to transfer protons int ...[more]

PMID: 32285908

Similar Datasets

Project description:Lysosomal storage disorders (LSDs) are a large group of more than 50 different inherited metabolic diseases which, in the great majority of cases, result from the defective function of specific lysosomal enzymes and, in few cases, of non-enzymatic lysosomal proteins or non-lysosomal proteins involved in lysosomal biogenesis. The progressive lysosomal accumulation of undegraded metabolites results in generalised cell and tissue dysfunction, and, therefore, multi-systemic pathology. Storage may begin during early embryonic development, and the clinical presentation for LSDs can vary from an early and severe phenotype to late-onset mild disease. The diagnosis of most LSDs--after accurate clinical/paraclinical evaluation, including the analysis of some urinary metabolites--is based mainly on the detection of a specific enzymatic deficiency. In these cases, molecular genetic testing (MGT) can refine the enzymatic diagnosis. Once the genotype of an individual LSD patient has been ascertained, genetic counselling should include prediction of the possible phenotype and the identification of carriers in the family at risk. MGT is essential for the identification of genetic disorders resulting from non-enzymatic lysosomal protein defects and is complementary to biochemical genetic testing (BGT) in complex situations, such as in cases of enzymatic pseudodeficiencies. Prenatal diagnosis is performed on the most appropriate samples, which include fresh or cultured chorionic villus sampling or cultured amniotic fluid. The choice of the test--enzymatic and/or molecular--is based on the characteristics of the defect to be investigated. For prenatal MGT, the genotype of the family index case must be known. The availability of both tests, enzymatic and molecular, enormously increases the reliability of the entire prenatal diagnostic procedure. To conclude, BGT and MGT are mostly complementary for post- and prenatal diagnosis of LSDs. Whenever genotype/phenotype correlations are available, they can be helpful in prognosis and in making decisions about therapy.

Project description:Abstract Acetyl-dl-leucine is a derivative of the branched chain amino acid leucine. In observational clinical studies, acetyl-dl-leucine improved symptoms of ataxia, in particular in patients with the lysosomal storage disorder, Niemann-Pick disease type C1. Here, we investigated acetyl-dl-leucine and its enantiomers acetyl-l-leucine and acetyl-d-leucine in symptomatic Npc1?/? mice and observed improvement in ataxia with both individual enantiomers and acetyl-dl-leucine. When acetyl-dl-leucine and acetyl-l-leucine were administered pre-symptomatically to Npc1?/? mice, both treatments delayed disease progression and extended life span, whereas acetyl-d-leucine did not. These data are consistent with acetyl-l-leucine being the neuroprotective enantiomer. Altered glucose and antioxidant metabolism were implicated as one of the potential mechanisms of action of the l-enantiomer in Npc1?/? mice. When the standard of care drug miglustat and acetyl-dl-leucine were used in combination significant synergy resulted. In agreement with these pre-clinical data, when Niemann-Pick disease type C1 patients were evaluated after 12 months of acetyl-dl-leucine treatment, rates of disease progression were slowed, with stabilization or improvement in multiple neurological domains. A beneficial effect of acetyl-dl-leucine on gait was also observed in this study in a mouse model of GM2 gangliosidosis (Sandhoff disease) and in Tay-Sachs and Sandhoff disease patients in individual-cases of off-label-use. Taken together, we have identified an unanticipated neuroprotective effect of acetyl-l-leucine and underlying mechanisms of action in lysosomal storage diseases, supporting its further evaluation in clinical trials in lysosomal disorders. This study investigates the disease-modifying effect of acetyl-DL-leucine in two neurodegenerative lysosomal storage diseases with different aetiologies: Niemann-Pick type C and GM2 gangliosidosis in both murine models and clinical studies. Acetyl-DL-leucine and its L enantiomer provide neuroprotection likely by altering metabolism – a new therapeutic approach for these diseases. Graphical Abstract Graphical Abstract

Dataset Information

Chloroquine and bafilomycin A mimic lysosomal storage disorders and impair mTORC1 signalling.

Publications

Chloroquine and bafilomycin A mimic lysosomal storage disorders and impair mTORC1 signalling.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets