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Mulligan RJ, Magaj MM, Digilio L, Redemann S, Yap CC, Winckler B. Collapse of late endosomal pH elicits a rapid Rab7 response via the V-ATPase and RILP. J Cell Sci 2024; 137:jcs261765. [PMID: 38578235 PMCID: PMC11166203 DOI: 10.1242/jcs.261765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 03/26/2024] [Indexed: 04/06/2024] Open
Abstract
Endosomal-lysosomal trafficking is accompanied by the acidification of endosomal compartments by the H+-V-ATPase to reach low lysosomal pH. Disruption of the correct pH impairs lysosomal function and the balance of protein synthesis and degradation (proteostasis). Here, we treated mammalian cells with the small dipeptide LLOMe, which is known to permeabilize lysosomal membranes, and find that LLOMe also impacts late endosomes (LEs) by neutralizing their pH without causing membrane permeabilization. We show that LLOMe leads to hyperactivation of Rab7 (herein referring to Rab7a), and disruption of tubulation and mannose-6-phosphate receptor (CI-M6PR; also known as IGF2R) recycling on pH-neutralized LEs. pH neutralization (NH4Cl) and expression of Rab7 hyperactive mutants alone can both phenocopy the alterations in tubulation and CI-M6PR trafficking. Mechanistically, pH neutralization increases the assembly of the V1G1 subunit (encoded by ATP6V1G1) of the V-ATPase on endosomal membranes, which stabilizes GTP-bound Rab7 via RILP, a known interactor of Rab7 and V1G1. We propose a novel pathway by which V-ATPase and RILP modulate LE pH and Rab7 activation in concert. This pathway might broadly contribute to pH control during physiologic endosomal maturation or starvation and during pathologic pH neutralization, which occurs via lysosomotropic compounds and in disease states.
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Affiliation(s)
- Ryan J. Mulligan
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908, USA
- Cell and Developmental Biology Graduate Program, University of Virginia, Charlottesville, VA 22908, USA
- Medical Scientist Training Program, University of Virginia, Charlottesville, VA 22908, USA
| | - Magdalena M. Magaj
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
- Cell and Developmental Biology Graduate Program, University of Virginia, Charlottesville, VA 22908, USA
| | - Laura Digilio
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908, USA
| | - Stefanie Redemann
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908, USA
| | - Chan Choo Yap
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908, USA
| | - Bettina Winckler
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908, USA
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Mulligan R, Magaj M, Digilio L, Redemann S, Yap C, Winckler B. Collapse of late endosomal pH elicits a rapid Rab7 response via V-ATPase and RILP. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.24.563658. [PMID: 37961579 PMCID: PMC10634777 DOI: 10.1101/2023.10.24.563658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Endosomal-lysosomal trafficking is accompanied by the acidification of endosomal compartments by the H+-V-ATPase to reach low lysosomal pH. Disruption of proper pH impairs lysosomal function and the balance of protein synthesis and degradation (proteostasis). We used the small dipeptide LLOMe, which is known to permeabilize lysosomal membranes, and find that LLOMe also impacts late endosomes (LEs) by neutralizing their pH without causing membrane permeabilization. We show that LLOMe leads to hyper-activation of Rab7 and disruption of tubulation and mannose-6-phosphate receptor (CI-M6PR) recycling on pH-neutralized LEs. Either pH neutralization (NH4Cl) or Rab7 hyper-active mutants alone can phenocopy the alterations in tubulation and CI-M6PR trafficking. Mechanistically, pH neutralization increases the assembly of the V1G1 subunit of the V-ATPase on endosomal membranes, which stabilizes GTP-bound Rab7 via RILP, a known interactor of Rab7 and V1G1. We propose a novel pathway by which V-ATPase and RILP modulate LE pH and Rab7 activation in concert. This pathway might broadly contribute to pH control during physiologic endosomal maturation or starvation and during pathologic pH neutralization, which occurs via lysosomotropic compounds or in disease states.
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Affiliation(s)
- R.J. Mulligan
- Department of Cell Biology, University of Virginia, Charlottesville, VA
- Cell and Developmental Biology Graduate Program, University of Virginia, Charlottesville, VA
- Medical Scientist Training Program, University of Virginia, Charlottesville, VA
| | - M.M. Magaj
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville VA
- Cell and Developmental Biology Graduate Program, University of Virginia, Charlottesville, VA
| | - L. Digilio
- Department of Cell Biology, University of Virginia, Charlottesville, VA
| | - S. Redemann
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville VA
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA
| | - C.C. Yap
- Department of Cell Biology, University of Virginia, Charlottesville, VA
| | - B Winckler
- Department of Cell Biology, University of Virginia, Charlottesville, VA
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Abbasi-Malati Z, Azizi SG, Milani SZ, Serej ZA, Mardi N, Amiri Z, Sanaat Z, Rahbarghazi R. Tumorigenic and tumoricidal properties of exosomes in cancers; a forward look. Cell Commun Signal 2024; 22:130. [PMID: 38360641 PMCID: PMC10870553 DOI: 10.1186/s12964-024-01510-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 02/01/2024] [Indexed: 02/17/2024] Open
Abstract
In recent decades, emerging data have highlighted the critical role of extracellular vesicles (EVs), especially (exosomes) Exos, in the progression and development of several cancer types. These nano-sized vesicles are released by different cell lineages within the cancer niche and maintain a suitable platform for the interchange of various signaling molecules in a paracrine manner. Based on several studies, Exos can transfer oncogenic factors to other cells, and alter the activity of immune cells, and tumor microenvironment, leading to the expansion of tumor cells and metastasis to the remote sites. It has been indicated that the cell-to-cell crosstalk is so complicated and a wide array of factors are involved in this process. How and by which mechanisms Exos can regulate the behavior of tumor cells and non-cancer cells is at the center of debate. Here, we scrutinize the molecular mechanisms involved in the oncogenic behavior of Exos released by different cell lineages of tumor parenchyma. Besides, tumoricidal properties of Exos from various stem cell (SC) types are discussed in detail.
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Affiliation(s)
- Zahra Abbasi-Malati
- Department of Applied Cell Sciences, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Seyed Ghader Azizi
- Clinical Immunology Research Center, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Soheil Zamen Milani
- Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Zeinab Aliyari Serej
- Department of Applied Cell Sciences, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Narges Mardi
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Zahra Amiri
- Department of Tissue Engineering, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Zohreh Sanaat
- Hematology and Oncology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Reza Rahbarghazi
- Department of Applied Cell Sciences, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran.
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
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Elabd S, Pauletto E, Solozobova V, Eickhoff N, Padrao N, Zwart W, Blattner C. TRIM25 targets p300 for degradation. Life Sci Alliance 2023; 6:e202301980. [PMID: 37770115 PMCID: PMC10539465 DOI: 10.26508/lsa.202301980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 09/18/2023] [Accepted: 09/19/2023] [Indexed: 10/01/2023] Open
Abstract
p300 is an important transcriptional co-factor. By stimulating the transfer of acetyl residues onto histones and several key transcription factors, p300 enhances transcriptional initiation and impacts cellular processes including cell proliferation and cell division. Despite its importance for cellular homeostasis, its regulation is poorly understood. We show that TRIM25, a member of the TRIM protein family, targets p300 for proteasomal degradation. However, despite TRIM25's RING domain and E3 activity, degradation of p300 by TRIM25 is independent of TRIM25-mediated p300 ubiquitination. Instead, TRIM25 promotes the interaction of p300 with dynein, which ensures a microtubule-dependent transport of p300 to cellular proteasomes. Through mediating p300 degradation, TRIM25 affects p300-dependent gene expression.
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Affiliation(s)
- Seham Elabd
- Institute for Biological and Chemical Systems - Biological Information Processing, Karlsruhe, Germany
- https://ror.org/00mzz1w90 Human Physiology Department, Medical Research Institute, Alexandria University, Alexandria, Egypt
| | - Eleonora Pauletto
- Institute for Biological and Chemical Systems - Biological Information Processing, Karlsruhe, Germany
| | - Valeria Solozobova
- Institute for Biological and Chemical Systems - Biological Information Processing, Karlsruhe, Germany
| | - Nils Eickhoff
- Division of Oncogenomics, Oncode Institute, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Nuno Padrao
- Division of Oncogenomics, Oncode Institute, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Wilbert Zwart
- Division of Oncogenomics, Oncode Institute, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Christine Blattner
- Institute for Biological and Chemical Systems - Biological Information Processing, Karlsruhe, Germany
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Mulligan RJ, Winckler B. Regulation of Endosomal Trafficking by Rab7 and Its Effectors in Neurons: Clues from Charcot-Marie-Tooth 2B Disease. Biomolecules 2023; 13:1399. [PMID: 37759799 PMCID: PMC10527268 DOI: 10.3390/biom13091399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 09/09/2023] [Accepted: 09/14/2023] [Indexed: 09/29/2023] Open
Abstract
Intracellular endosomal trafficking controls the balance between protein degradation and synthesis, i.e., proteostasis, but also many of the cellular signaling pathways that emanate from activated growth factor receptors after endocytosis. Endosomal trafficking, sorting, and motility are coordinated by the activity of small GTPases, including Rab proteins, whose function as molecular switches direct activity at endosomal membranes through effector proteins. Rab7 is particularly important in the coordination of the degradative functions of the pathway. Rab7 effectors control endosomal maturation and the properties of late endosomal and lysosomal compartments, such as coordination of recycling, motility, and fusion with downstream compartments. The spatiotemporal regulation of endosomal receptor trafficking is particularly challenging in neurons because of their enormous size, their distinct intracellular domains with unique requirements (dendrites vs. axons), and their long lifespans as postmitotic, differentiated cells. In Charcot-Marie-Tooth 2B disease (CMT2B), familial missense mutations in Rab7 cause alterations in GTPase cycling and trafficking, leading to an ulcero-mutilating peripheral neuropathy. The prevailing hypothesis to account for CMT2B pathologies is that CMT2B-associated Rab7 alleles alter endocytic trafficking of the neurotrophin NGF and its receptor TrkA and, thereby, disrupt normal trophic signaling in the peripheral nervous system, but other Rab7-dependent pathways are also impacted. Here, using TrkA as a prototypical endocytic cargo, we review physiologic Rab7 effector interactions and control in neurons. Since neurons are among the largest cells in the body, we place particular emphasis on the temporal and spatial regulation of endosomal sorting and trafficking in neuronal processes. We further discuss the current findings in CMT2B mutant Rab7 models, the impact of mutations on effector interactions or balance, and how this dysregulation may confer disease.
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Affiliation(s)
- Ryan J. Mulligan
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22903, USA
- Medical Scientist Training Program, University of Virginia, Charlottesville, VA 22903, USA
| | - Bettina Winckler
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22903, USA
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Yap CC, Digilio L, McMahon L, Winckler B. "Disruption of Golgi markers by two RILP-directed shRNAs in neurons: a new role for RILP or a neuron-specific off-target phenotype?". J Biol Chem 2023:104916. [PMID: 37315786 PMCID: PMC10362152 DOI: 10.1016/j.jbc.2023.104916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 05/04/2023] [Accepted: 05/31/2023] [Indexed: 06/16/2023] Open
Abstract
In neurons, degradation of dendritic cargos requires RAB7 and dynein-mediated retrograde transport to somatic lysosomes. To test if the dynein adaptor RILP (RAB-interacting lysosomal protein) mediated the recruitment of dynein to late endosomes for retrograde transport in dendrites, we obtained several knockdown reagents previously validated in non-neuronal cells. Striking endosomal phenotypes elicited by one shRILP plasmid were not reproduced by another one. Furthermore, we discovered a profound depletion of Golgi/TGN markers for both shRILP plasmids. This Golgi disruption was only observed in neurons and could not be rescued by re-expression of RILP. This Golgi phenotype was also not found in neurons treated with siRILP or gRILP/Cas9. Lastly, we tested if a different RAB protein that interacts with RILP, namely the Golgi-associated RAB34, might be responsible for the loss of Golgi markers. Expression of a dominant-negative RAB34 did indeed cause changes in Golgi staining in a small subset of neurons but manifested as fragmentation rather than loss of staining. Unlike in non-neuronal cells, interference with RAB34 did not cause dispersal of lysosomes in neurons. Based on multiple lines of experimentation, we conclude that the neuronal Golgi phenotype observed with shRILP is likely off-target in this cell type specifically. Any observed disruptions of endosomal trafficking caused by shRILP in neurons might thus be downstream of Golgi disruption. It would be interesting to identify the actual target for this neuronal Golgi phenotype. Cell type-specific off-target phenotypes therefore likely occur in neurons, necessitating re-validation of reagents that were previously validated in other cell types.
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Affiliation(s)
- Chan Choo Yap
- Department of Cell Biology, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall 3226, Charlottesville, VA 22908, USA.
| | - Laura Digilio
- Department of Cell Biology, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall 3226, Charlottesville, VA 22908, USA
| | - Lloyd McMahon
- Department of Cell Biology, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall 3226, Charlottesville, VA 22908, USA
| | - Bettina Winckler
- Department of Cell Biology, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall 3226, Charlottesville, VA 22908, USA.
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Yap CC, Digilio L, McMahon L, Winckler B. "Disruption of Golgi markers by two RILP-directed shRNAs in neurons: a new role for RILP or a neuron-specific off-target phenotype?". BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.08.531742. [PMID: 36945482 PMCID: PMC10028860 DOI: 10.1101/2023.03.08.531742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
In neurons, degradation of dendritic cargos requires RAB7 and dynein-mediated retrograde transport to somatic lysosomes. In order to test if the dynein adaptor RILP (RAB-interacting lysosomal protein) mediated the recruitment of dynein to late endosomes for retrograde transport in dendrites, we obtained several knockdown reagents which had been previously validated in non-neuronal cells. We found that striking endosomal phenotypes elicited by one shRILP plasmid were not reproduced by another one. Furthermore, we discovered a profound depletion of Golgi/TGN markers for both shRILP plasmids. This Golgi disruption was only observed in neurons and could not be rescued by re-expression of RILP. This Golgi phenotype was also not found in neurons treated with siRILP or gRILP/Cas9. Lastly, we tested if a different RAB protein that interacts with RILP, namely the Golgi-associated RAB34, might be responsible for the loss of Golgi markers. Expression of a dominant-negative RAB34 did indeed cause changes in Golgi staining in a small subset of neurons but manifested as fragmentation rather than loss of markers. Unlike in non-neuronal cells, interference with RAB34 did not cause dispersal of lysosomes in neurons. Based on multiple lines of experimentation, we conclude that the neuronal Golgi phenotype observed with shRILP is likely off-target in this cell type specifically. Any observed disruptions of endosomal trafficking caused by shRILP in neurons might thus be downstream of Golgi disruption. Different approaches will be needed to test if RILP is required for late endosomal transport in dendrites. Cell type-specific off-target phenotypes therefore likely occur in neurons, making it prudent to re-validate reagents that were previously validated in other cell types.
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Affiliation(s)
- Chan Choo Yap
- Corresponding authors: Bettina Winckler and Chan Choo Yap, Phone: (434)924-5528/5526. ,
| | | | | | - Bettina Winckler
- Corresponding authors: Bettina Winckler and Chan Choo Yap, Phone: (434)924-5528/5526. ,
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Yang Y, Shao M, Yao J, Yang S, Cheng W, Ma L, Li W, Cao J, Zhang Y, Hu Y, Li C, Wang Y, Wang W. Neocryptotanshinone protects against myocardial ischemia-reperfusion injury by promoting autolysosome degradation of protein aggregates via the ERK1/2-Nrf2-LAMP2 pathway. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2023; 110:154625. [PMID: 36586206 DOI: 10.1016/j.phymed.2022.154625] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 12/04/2022] [Accepted: 12/23/2022] [Indexed: 06/17/2023]
Abstract
BACKGROUND Aggrephagy is a critical compensatory mechanism for the elimination of misfolded proteins resulting from stress and depends on the autolysosome degradation of protein aggregates. However, there have been few mechanism research related to aggrephagy in myocardial ischemia/reperfusion (I/R) injury. Neocryptotanshinone (NCTS) is a fat-soluble active compound extracted from Salvia miltiorrhiza, and may be cardioprotective against I/R. However, the efficacy and specific mechanism of NCTS on I/R have not been studied. PURPOSE The current study aimed to investigate the molecular mechanism of NCTS involved in the therapeutic effect on I/R, with a special emphasis on the up-regulation of the ERK1/2-Nrf2-LAMP2 pathway to increase autolysosomal degradation during aggrephagy. METHODS A rat model of myocardial I/R injury was constructed by left anterior descending (LAD) ligation-reperfusion. To verify cardiac protection, autolysosome clearance of protein aggregates, and their intracellular biological mechanism, an oxygen-glucose deprivation/recovery (OGD/R)-induced H9c2 cardiomyocyte model was created. RESULTS NCTS was found to have a significant cardioprotective effect in I/R rats as evidenced by remarkably improved pathological anatomy, decreased myocardial damage indicators, and substantially enhanced cardiac performance. Mechanistically, NCTS might boost the levels of LAMP2 mRNA and protein, total and Ser40 phosphorylated Nrf2, and Thr202/Tyr204p-ERK1/2 protein. Simultaneously, the cytoplasmic Nrf2 level was reduced after NCTS administration, which was contrary to the total Nrf2 content. However, these beneficial changes were reversed by the co-administration with ERK1/2 inhibitor, PD98059. NCTS therapy up-regulated Rab7 protein content, Cathepsin B activity, and lysosomal acidity, while down-regulating autophagosome numbers, Ubiquitin (Ub), and autophagosome marker protein accumulations through the above signaling pathway. This might indicate that NCTS enhanced lysosomal fusion and hydrolytic capacity. It was also found that NCTS intervention limited oxidative stress and cellular apoptosis both in vivo and in vitro. CONCLUSIONS We reported for the first time that NCTS promoted the autolysosome removal of protein aggregation both in vivo and in vitro, to exert the therapeutic advantages of myocardial I/R injury. This was reliant on the up-regulation of the ERK1/2-Nrf2-LAMP2 signaling pathway.
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Affiliation(s)
- Ye Yang
- Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing 100700, China; Key Laboratory of TCM Syndrome and Formula (Beijing University of Chinese Medicine), Ministry of Education, Beijing 100700, China
| | - Mingyan Shao
- Key Laboratory of TCM Syndrome and Formula (Beijing University of Chinese Medicine), Ministry of Education, Beijing 100700, China; School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Junkai Yao
- Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing 100700, China; Key Laboratory of TCM Syndrome and Formula (Beijing University of Chinese Medicine), Ministry of Education, Beijing 100700, China
| | - Shuangjie Yang
- School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Wenkun Cheng
- Key Laboratory of TCM Syndrome and Formula (Beijing University of Chinese Medicine), Ministry of Education, Beijing 100700, China; School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Lin Ma
- Key Laboratory of TCM Syndrome and Formula (Beijing University of Chinese Medicine), Ministry of Education, Beijing 100700, China; School of Life Sciences, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Weili Li
- Key Laboratory of TCM Syndrome and Formula (Beijing University of Chinese Medicine), Ministry of Education, Beijing 100700, China; School of Life Sciences, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Jing Cao
- Key Laboratory of TCM Syndrome and Formula (Beijing University of Chinese Medicine), Ministry of Education, Beijing 100700, China; School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Yawen Zhang
- Key Laboratory of TCM Syndrome and Formula (Beijing University of Chinese Medicine), Ministry of Education, Beijing 100700, China; School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Yueyao Hu
- Key Laboratory of TCM Syndrome and Formula (Beijing University of Chinese Medicine), Ministry of Education, Beijing 100700, China; School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Chun Li
- Key Laboratory of TCM Syndrome and Formula (Beijing University of Chinese Medicine), Ministry of Education, Beijing 100700, China; Modern Research Center for Traditional Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China.
| | - Yong Wang
- Key Laboratory of TCM Syndrome and Formula (Beijing University of Chinese Medicine), Ministry of Education, Beijing 100700, China; School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing 100029, China.
| | - Wei Wang
- Key Laboratory of TCM Syndrome and Formula (Beijing University of Chinese Medicine), Ministry of Education, Beijing 100700, China; Guangzhou University of Chinese Medicine, Guangzhou 510006, China.
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Kulkarni VV, Stempel MH, Anand A, Sidibe DK, Maday S. Retrograde Axonal Autophagy and Endocytic Pathways Are Parallel and Separate in Neurons. J Neurosci 2022; 42:8524-8541. [PMID: 36167783 PMCID: PMC9665928 DOI: 10.1523/jneurosci.1292-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/15/2022] [Accepted: 09/20/2022] [Indexed: 11/21/2022] Open
Abstract
Autophagy and endocytic trafficking are two key pathways that regulate the composition and integrity of the neuronal proteome. Alterations in these pathways are sufficient to cause neurodevelopmental and neurodegenerative disorders. Thus, defining how autophagy and endocytic pathways are organized in neurons remains a key area of investigation. These pathways share many features and converge on lysosomes for cargo degradation, but what remains unclear is the degree to which the identity of each pathway is preserved in each compartment of the neuron. Here, we elucidate the degree of intersection between autophagic and endocytic pathways in axons of primary mouse cortical neurons of both sexes. Using microfluidic chambers, we labeled newly-generated bulk endosomes and signaling endosomes in the distal axon, and systematically tracked their trajectories, molecular composition, and functional characteristics relative to autophagosomes. We find that newly-formed endosomes and autophagosomes both undergo retrograde transport in the axon, but as distinct organelle populations. Moreover, these pathways differ in their degree of acidification and association with molecular determinants of organelle maturation. These results suggest that the identity of autophagic and newly endocytosed organelles is preserved for the length of the axon. Lastly, we find that expression of a pathogenic form of α-synuclein, a protein enriched in presynaptic terminals, increases merging between autophagic and endocytic pathways. Thus, aberrant merging of these pathways may represent a mechanism contributing to neuronal dysfunction in Parkinson's disease (PD) and related α-synucleinopathies.SIGNIFICANCE STATEMENT Autophagy and endocytic trafficking are retrograde pathways in neuronal axons that fulfill critical degradative and signaling functions. These pathways share many features and converge on lysosomes for cargo degradation, but the extent to which the identity of each pathway is preserved in axons is unclear. We find that autophagosomes and endosomes formed in the distal axon undergo retrograde transport to the soma in parallel and separate pathways. These pathways also have distinct maturation profiles along the mid-axon, further highlighting differences in the potential fate of transported cargo. Strikingly, expression of a pathogenic variant of α-synuclein increases merging between autophagic and endocytic pathways, suggesting that mis-sorting of axonal cargo may contribute to neuronal dysfunction in Parkinson's disease (PD) and related α-synucleinopathies.
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Affiliation(s)
- Vineet Vinay Kulkarni
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Max Henry Stempel
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Anip Anand
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - David Kader Sidibe
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Sandra Maday
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
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Yap CC, Winckler B. Expected and unexpected roles for dynein regulation of dendritic late endosomes. AUTOPHAGY REPORTS 2022; 1:570-575. [PMID: 36969095 PMCID: PMC10035078 DOI: 10.1080/27694127.2022.2142888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Dendrites differ from axons in multiple ways, including the presence of minus-end out microtubules intermixed with the more conventional plus-end out microtubules. The mixed microtubule polarity makes regulation of directional transport in dendrites a challenge. Dynein can in principle be a retrograde and anterograde motor in dendrites. We show in our recent paper that dynein supports bi-directional transport of late endosomes in dendrites. We also show that overexpression of the RAB7 effector RILP which recruits dynein to late endosomes imparts retrograde bias onto late endosomes. Inhibition of dynein leads to a decrease in bi-directional motility of late endosomes, an expected result. Unexpectedly, inhibition of dynein also impairs endosome maturation as evidenced by increased association of GTP-RAB7 with late endosomes. Ultimately, dynein inhibition causes degradation defects of short-lived dendritic receptors and stunted dendrite morphologies. Much more work is required to fully understand how endosomal pathways are regulated in time and space in dendrites. Given the prevalence of neurological disorders where endosome-lysosome functions are impaired, this is a topic of great translational relevance.
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Affiliation(s)
- Chan Choo Yap
- Department of Cell Biology, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall 3226, Charlottesville, VA 22908, USA
| | - Bettina Winckler
- Department of Cell Biology, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall 3226, Charlottesville, VA 22908, USA
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11
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Transport-dependent maturation of organelles in neurons. Curr Opin Cell Biol 2022; 78:102121. [PMID: 36030563 DOI: 10.1016/j.ceb.2022.102121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 07/15/2022] [Indexed: 01/31/2023]
Abstract
Some organelles show a spatial gradient of maturation along the neuronal process where more mature organelles are found closer to the cell body. This gradient is set up by progressive maturation steps that are aided by differential organelle distribution as well as transport. Autophagosomes and endosomes mature as they acquire lysosomal membrane proteins and decrease their luminal pH as they are retrogradely transported towards the cell body. The acquisition of lysosomal proteins along the neuronal processes likely occurs through fusion or membrane exchange events with Golgi-derived donor transport carriers that are transported anterogradely from the cell body. The mechanisms by which endosomes and autophagosomes mature might be applicable to other organelles that are transported along neuronal processes. Defects in axonal transport may also contribute to the accumulation of immature organelles in neurons. Such accumulations have been seen in neurons of neurodegenerative models.
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