CLN3 is required for the clearance of glycerophosphodiesters from lysosomes.
Lysosomes have many roles, including degrading macromolecules and signalling to the nucleus1. Lysosomal dysfunction occurs in various human conditions, such as common neurodegenerative diseases and monogenic lysosomal storage disorders (LSDs)2-4. For most LSDs, the causal genes have been identified but, in some, the function of the implicated gene is unknown, in part because lysosomes occupy a small fraction of the cellular volume so that changes in lysosomal contents are difficult to detect. Here we develop the LysoTag mouse for the tissue-specific isolation of intact lysosomes that are compatible with the multimodal profiling of their contents. We used the LysoTag mouse to study CLN3, a lysosomal transmembrane protein with an unknown function. In children, the loss of CLN3 causes juvenile neuronal ceroid lipofuscinosis (Batten disease), a lethal neurodegenerative LSD. Untargeted metabolite profiling of lysosomes from the brains of mice lacking CLN3 revealed a massive accumulation of glycerophosphodiesters (GPDs)-the end products of glycerophospholipid catabolism. GPDs also accumulate in the lysosomes of CLN3-deficient cultured cells and we show that CLN3 is required for their lysosomal egress. Loss of CLN3 also disrupts glycerophospholipid catabolism in the lysosome. Finally, we found elevated levels of glycerophosphoinositol in the cerebrospinal fluid of patients with Batten disease, suggesting the potential use of glycerophosphoinositol as a disease biomarker. Our results show that CLN3 is required for the lysosomal clearance of GPDs and reveal Batten disease as a neurodegenerative LSD with a defect in glycerophospholipid metabolism.
View details for DOI 10.1038/s41586-022-05221-y
View details for PubMedID 36131016
Isotope tracing in health and disease.
Current opinion in biotechnology
2022; 76: 102739
Biochemical characterization of metabolism provides molecular insights for understanding biology in health and disease. Over the past decades, metabolic perturbations have been implicated in cancer, neurodegeneration, and diabetes, among others. Isotope tracing is a technique that allows tracking of labeled atoms within metabolites through biochemical reactions. This technique has become an integral component of the contemporary metabolic research. Isotope tracing measures substrate contribution to downstream metabolites and indicates its utilization in cellular metabolic networks. In addition, isotopic labeling data are necessary for quantitative metabolicflux analysis. Here, we review recent work utilizing metabolic tracing to study health and disease, and highlight its application to interrogate subcellular, intercellular, and in vivo metabolism. We further discuss the current challenges and opportunities to expand the utility of isotope tracing to new research areas.
View details for DOI 10.1016/j.copbio.2022.102739
View details for PubMedID 35738210
Ferroptosis Regulation by the NGLY1/NFE2L1 Pathway.
FASEB journal : official publication of the Federation of American Societies for Experimental Biology
2022; 36 Suppl 1
Cells are equipped with various mechanisms to maintain cell viability upon exposure to stress. The Cap 'n' Collar (CNC) family includes five vertebrate stress-responsive transcription factors. The CNC member nuclear factor erythroid 2 like 2 (NFE2L2) is considered the master regulator of the cellular oxidative stress response. Fellow CNC member nuclear erythroid 2 like 1 (NFE2L1) is better known for its role in responding to proteasome dysfunction. We hypothesized that NFE2L1 also responds to oxidative stress. We demonstrate that genetic disruption of NFE2L1 sensitizes cancer cells to death by a non-apoptotic, oxidative form of cell death termed ferroptosis. We also show that genetic disruption of N-glycanase 1 (NGLY1), which catalyzes NFE2L1 deglycosylation and sequence editing, sensitizes cancer cells to ferroptosis through an NFE2L1-dependent mechanism. Expression of a sequence-edited NFE2L1 mutant, which mimics NGLY1-processed NFE2L1, rescues cellular resistance to ferroptosis in NFE2L1 gene-disrupted cells. Finally, we provide evidence that the ferroptosis protection conferred by NFE2L1 is mediated by the expression of glutathione peroxidase 4 (GPX4). All together, our results highlight the role of NFE2L1 in ferroptosis resistance and implicate NFE2L1 and NGLY1 as potential targets for cancer therapy.
View details for DOI 10.1096/fasebj.2022.36.S1.R2814
View details for PubMedID 35560739
Ferroptosis regulation by the NGLY1/NFE2L1 pathway.
Proceedings of the National Academy of Sciences of the United States of America
2022; 119 (11): e2118646119
SignificanceFerroptosis is an oxidative form of cell death whose biochemical regulation remains incompletely understood. Cap'n'collar (CNC) transcription factors including nuclear factor erythroid-2-related factor 1 (NFE2L1/NRF1) and NFE2L2/NRF2 can both regulate oxidative stress pathways but are each regulated in a distinct manner, and whether these two transcription factors can regulate ferroptosis independent of one another is unclear. We find that NFE2L1 can promote ferroptosis resistance, independent of NFE2L2, by maintaining the expression of glutathione peroxidase 4 (GPX4), a key protein that prevents lethal lipid peroxidation. NFE2L2 can also promote ferroptosis resistance but does so through a distinct mechanism that appears independent of GPX4 protein expression. These results suggest that NFE2L1 and NFE2L2 independently regulate ferroptosis.
View details for DOI 10.1073/pnas.2118646119
View details for PubMedID 35271393