Organelle proteomic profiling reveals lysosomal heterogeneity in association with longevity

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    These authors present a powerful tool to unbiasedly identify lysosome-associated proteins in C. elegans, and they provide a compelling, in-depth assessment of how this method can be used to understand longevity pathways and identify novel proteins. Understanding lysosomal differences in specific tissues or in response to different longevity conditions are exciting as it provides new insight into how organelles could control specific homeostasis responses. This valuable tool and proteomics datasets also represent a great resource for the C. elegans community and should pry open new studies on the regulation and role of the lysosome at the organismal level.

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Abstract

Lysosomes are active sites to integrate cellular metabolism and signal transduction. A collection of proteins associated with the lysosome mediate these metabolic and signaling functions. Both lysosomal metabolism and lysosomal signaling have been linked to longevity regulation; however, how lysosomes adjust their protein composition to accommodate this regulation remains unclear. Using deep proteomic profiling, we systemically profiled lysosome-associated proteins linked with four different longevity mechanisms. We discovered the lysosomal recruitment of AMP-activated protein kinase and nucleoporin proteins and their requirements for longevity in response to increased lysosomal lipolysis. Through comparative proteomic analyses of lysosomes from different tissues and labeled with different markers, we further elucidated lysosomal heterogeneity across tissues as well as the increased enrichment of the Ragulator complex on Cystinosin-positive lysosomes. Together, this work uncovers lysosomal proteome heterogeneity across multiple scales and provides resources for understanding the contribution of lysosomal protein dynamics to signal transduction, organelle crosstalk, and organism longevity.

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  1. Author Response

    Reviewer #1 (Public Review):

    This is a very exciting manuscript from Meng Wang's lab on lysosomal proteomics. They used several different protein tags to identify the lysosomal proteome. The exciting findings include A) specific lysosomal proteins exist in a tissue-specific manner B) lipl-4 overexpression and daf-2 extend life span using different mechanisms C) identification of novel lysosomal proteins D) demonstration of the function of several lysosomal proteins in regulation lysosome abundance and function.

    We thank the reviewer for finding our manuscript exciting.

    Reviewer #2 (Public Review):

    In this manuscript, Yu and colleagues profile the lysosome content in C. elegans. They implement lysosome immunoprecipitation (Lyso-IP) for C. elegans and they convincingly show that this method successfully isolates lysosomes from whole worms. The authors find that the lysosomes of worms overexpressing the lysosomal lipase lipl4 are enriched for AMPK subunits and nucleoporins and that these proteins are required for the longevity of lipl-4 overexpressing worms. The authors also show that this is specific to this longevity pathway given that another long-lived worm strain (daf2) does not exhibit enrichment for nucleoporins nor does it require them for longevity. The authors go on to express the Lyso-IP tag in different tissues of C. elegans (muscle, hypodermis, intestine, neurons) and identify the tissue-specific lysosome proteomes. Finally, the authors use this method to identify lysosome proteins in mature lysosomes and they find new proteins that regulate lysosomal acidification.

    The authors present a powerful tool to unbiasedly identify lysosome-associated proteins in C. elegans, and they provide an in-depth assessment of how this method can be used to understand longevity pathways and identify novel proteins. Understanding lysosomal differences in specific tissues or in response to different longevity conditions are exciting as it provides new insight into how organelles could control specific homeostasis responses. This tool and proteomics datasets also represent a great resource for the C. elegans community and should pry open new studies on the regulation and role of the lysosome at the organismal level.

    We truly appreciate that the reviewer’s positive comment on our work.

    Addressing the following suggestions would help strengthen this already strong manuscript. First, it would be helpful to validate selected candidates from the tissuespecific Lyso-IP to verify that the protocol is still specific with lower sample amounts. Second, it would be helpful to provide more details on the methods, notably for sample preparation and analysis, so that it can serve as a guideline for the community. Third, the manuscript contains a lot of data and conditions, which is great, but they may also feel disconnected in some cases and it could be helpful to focus the study on the main key findings.

    We thank the reviewer’s comments. As suggested by the reviewer, we have also generated a CRISPR knock-in line for one hypodermis-specific candidate Y58A7A.1 that encodes a copper transporter and validated its hypodermis-specific lysosomal localization (new Supplementary Figure 2E).

    As suggested by the reviewer, we have extended the method section on Lyso-IP to include more details. We believe that the new version should be sufficient for any lab to follow this protocol and conduct their own analyses. We will also take advantage of the eLife “Request a Protocol” feature to share the detailed version of the Lyso-IP method with researchers who are interested.

    We have thoroughly reorganized the manuscript to increase the textual clarity and improve the connection between different analyses and results.

    Reviewer #3 (Public Review):

    The manuscript by Ji et al dissects the important role of lysosomes in cellular metabolism and signaling and their regulation by various associated proteins. The authors utilized deep proteomic profiling in C.Elegans to identify lysosome-associated proteins involved in regulating longevity and discovered the recruitment of AMPK and nucleoporin proteins in response to increased lysosomal lipolysis. Additionally, the authors found lysosomal heterogeneity across different tissues and specific enrichment of the Ragulator complex on Cystinosin-positive lysosomes.

    Strengths of this work include the utilization of deep proteomic profiling to identify novel lysosome-associated proteins involved in longevity regulation, as well as the discovery of lysosomal heterogeneity and specific protein enrichments across different worm tissues. These findings point to a complex interplay between lysosomal protein dynamics, signal transduction, organelle crosstalk, and organism longevity.

    One weakness of this work may be the limited scope of the study, as it focuses primarily on the identification and characterization of lysosome-associated proteins involved in longevity regulation, with limited mechanistic follow-up and some unsubstantiated claims.

    We thank the reviewer for her/his helpful comments and suggestions. The primary goal of this manuscript is to provide new methods and resource to the community. We did have several biological findings from the current study, and mechanistic follow-up with these findings will be interesting future topics but may beyond the scope of the current manuscript. In addition, we have provided new experimental results to further support several claims that the reviewer has commented on.

  2. eLife assessment

    These authors present a powerful tool to unbiasedly identify lysosome-associated proteins in C. elegans, and they provide a compelling, in-depth assessment of how this method can be used to understand longevity pathways and identify novel proteins. Understanding lysosomal differences in specific tissues or in response to different longevity conditions are exciting as it provides new insight into how organelles could control specific homeostasis responses. This valuable tool and proteomics datasets also represent a great resource for the C. elegans community and should pry open new studies on the regulation and role of the lysosome at the organismal level.

  3. Reviewer #1 (Public Review):

    This is a very exciting manuscript from Meng Wang's lab on lysosomal proteomics. They used several different protein tags to identify the lysosomal proteome. The exciting findings include A) specific lysosomal proteins exist in a tissue-specific manner B) lipl-4 overexpression and daf-2 extend life span using different mechanisms C) identification of novel lysosomal proteins D) demonstration of the function of several lysosomal proteins in regulation lysosome abundance and function.

  4. Reviewer #2 (Public Review):

    In this manuscript, Yu and colleagues profile the lysosome content in C. elegans. They implement lysosome immunoprecipitation (Lyso-IP) for C. elegans and they convincingly show that this method successfully isolates lysosomes from whole worms. The authors find that the lysosomes of worms overexpressing the lysosomal lipase lipl-4 are enriched for AMPK subunits and nucleoporins and that these proteins are required for the longevity of lipl-4 overexpressing worms. The authors also show that this is specific to this longevity pathway given that another long-lived worm strain (daf-2) does not exhibit enrichment for nucleoporins nor does it require them for longevity. The authors go on to express the Lyso-IP tag in different tissues of C. elegans (muscle, hypodermis, intestine, neurons) and identify the tissue-specific lysosome proteomes. Finally, the authors use this method to identify lysosome proteins in mature lysosomes and they find new proteins that regulate lysosomal acidification.

    The authors present a powerful tool to unbiasedly identify lysosome-associated proteins in C. elegans, and they provide an in-depth assessment of how this method can be used to understand longevity pathways and identify novel proteins. Understanding lysosomal differences in specific tissues or in response to different longevity conditions are exciting as it provides new insight into how organelles could control specific homeostasis responses. This tool and proteomics datasets also represent a great resource for the C. elegans community and should pry open new studies on the regulation and role of the lysosome at the organismal level.

    Addressing the following suggestions would help strengthen this already strong manuscript. First, it would be helpful to validate selected candidates from the tissue-specific Lyso-IP to verify that the protocol is still specific with lower sample amounts. Second, it would be helpful to provide more details on the methods, notably for sample preparation and analysis, so that it can serve as a guideline for the community. Third, the manuscript contains a lot of data and conditions, which is great, but they may also feel disconnected in some cases and it could be helpful to focus the study on the main key findings.

  5. Reviewer #3 (Public Review):

    The manuscript by Ji et al dissects the important role of lysosomes in cellular metabolism and signaling and their regulation by various associated proteins. The authors utilized deep proteomic profiling in C.Elegans to identify lysosome-associated proteins involved in regulating longevity and discovered the recruitment of AMPK and nucleoporin proteins in response to increased lysosomal lipolysis. Additionally, the authors found lysosomal heterogeneity across different tissues and specific enrichment of the Ragulator complex on Cystinosin-positive lysosomes.

    Strengths of this work include the utilization of deep proteomic profiling to identify novel lysosome-associated proteins involved in longevity regulation, as well as the discovery of lysosomal heterogeneity and specific protein enrichments across different worm tissues. These findings point to a complex interplay between lysosomal protein dynamics, signal transduction, organelle crosstalk, and organism longevity.

    One weakness of this work may be the limited scope of the study, as it focuses primarily on the identification and characterization of lysosome-associated proteins involved in longevity regulation, with limited mechanistic follow-up and some unsubstantiated claims.