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Coupling APEX labeling to imaging mass spectrometry of single organelles reveals heterogeneity in lysosomal protein turnover.

ABSTRACT: Quantification of stable isotope tracers after metabolic labeling provides a snapshot of the dynamic state of living cells and tissue. A form of imaging mass spectrometry quantifies isotope ratios with a lateral resolution <50 nm, using a methodology that we refer to as multi-isotope imaging mass spectrometry (MIMS). Despite lateral resolution exceeding diffraction-limited light microscopy, lack of contrast has largely limited use of MIMS to large or specialized subcellular structures, such as the nucleus and stereocilia. In this study, we repurpose the engineered peroxidase APEX2 as the first genetically encoded marker for MIMS. Coupling APEX2 labeling of lysosomes and metabolic labeling of protein, we identify that individual lysosomes exhibit substantial heterogeneity in protein age, which is lost in iPSC-derived neurons lacking the lysosomal protein progranulin. This study expands the practical use of MIMS for cell biology by enabling measurements of metabolic function from stable isotope labeling within individual organelles in situ.

SUBMITTER: Narendra DP

PROVIDER: S-EPMC7039203 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Coupling APEX labeling to imaging mass spectrometry of single organelles reveals heterogeneity in lysosomal protein turnover.

Narendra Derek P DP Guillermier Christelle C Gyngard Frank F Huang Xiaoping X Ward Michael E ME Steinhauser Matthew L ML Steinhauser Matthew L ML

The Journal of cell biology 20200101 1

Quantification of stable isotope tracers after metabolic labeling provides a snapshot of the dynamic state of living cells and tissue. A form of imaging mass spectrometry quantifies isotope ratios with a lateral resolution <50 nm, using a methodology that we refer to as multi-isotope imaging mass spectrometry (MIMS). Despite lateral resolution exceeding diffraction-limited light microscopy, lack of contrast has largely limited use of MIMS to large or specialized subcellular structures, such as t ...[more]

PMID: 31719114

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Coupling APEX labeling to imaging mass spectrometry of single organelles reveals heterogeneity in lysosomal protein turnover.

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Coupling APEX labeling to imaging mass spectrometry of single organelles reveals heterogeneity in lysosomal protein turnover.

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