The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Shawn M. Ferguson - One of the best experts on this subject based on the ideXlab platform.
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minimal membrane interactions conferred by rheb c terminal farnesylation are essential for mtorc1 activation
bioRxiv, 2019Co-Authors: Brittany Angarola, Shawn M. FergusonAbstract:Stable localization of the Rheb GTPase to Lysosomes is thought to be required for activation of mTORC1 signaling. However, the Lysosome targeting mechanisms for Rheb remain unclear. We therefore investigated the relationship between Rheb subcellular localization and mTORC1 activation. Surprisingly, we found that although Rheb was prominently enriched at the endoplasmic reticulum (ER), Rheb was undetectable at Lysosomes. Functional assays in knockout human cells revealed that farnesylation of the C-terminal CaaX motif on Rheb was essential for both Rheb enrichment on ER membranes and mTORC1 activation. However, constitutively targeting Rheb to ER membranes did not support mTORC1 activation. Further systematic analysis of the Rheb hypervariable region revealed that weak, non-selective, farnesylation-dependent, membrane interactions confer Rheb function without the need for a specific Lysosome targeting motif. Collectively, these results argue against stable interactions of Rheb with Lysosomes and instead that transient membrane interactions optimally allow Rheb to activate mTORC1 signaling.
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gator1 dependent recruitment of flcn fnip to Lysosomes coordinates rag gtpase heterodimer nucleotide status in response to amino acids
Journal of Cell Biology, 2018Co-Authors: Jin Meng, Shawn M. FergusonAbstract:Folliculin (FLCN) is a tumor suppressor that coordinates cellular responses to changes in amino acid availability via regulation of the Rag guanosine triphosphatases. FLCN is recruited to Lysosomes during amino acid starvation, where it interacts with RagA/B as a heterodimeric complex with FLCN-interacting proteins (FNIPs). The FLCN–FNIP heterodimer also has GTPase-activating protein (GAP) activity toward RagC/D. These properties raised two important questions. First, how is amino acid availability sensed to regulate lysosomal abundance of FLCN? Second, what is the relationship between FLCN Lysosome localization, RagA/B interactions, and RagC/D GAP activity? In this study, we show that RagA/B nucleotide status determines the FLCN–FNIP1 recruitment to Lysosomes. Starvation-induced FLCN–FNIP Lysosome localization requires GAP activity toward Rags 1 (GATOR1), the GAP that converts RagA/B to the guanosine diphosphate (GDP)-bound state. This places FLCN–FNIP recruitment to Lysosomes under the control of amino acid sensors that act upstream of GATOR1. By binding to RagA/BGDP and acting on RagC/D, FLCN–FNIP can coordinate nucleotide status between Rag heterodimer subunits in response to changes in amino acid availability.
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Axonal transport and maturation of Lysosomes.
Current Opinion in Neurobiology, 2018Co-Authors: Shawn M. FergusonAbstract:Lysosomes perform degradative functions that are important for all cells. However, neurons are particularly dependent on optimal Lysosome function due to their extremes of longevity, size and polarity. Axons in particular exemplify the major spatial challenges faced by neurons in the maintenance of Lysosome biogenesis and function. What impact does this have on the regulation and functions of Lysosomes in axons? This review focuses on the mechanisms whereby axonal Lysosome biogenesis, transport and function are adapted to meet neuronal demand. Important features include the dynamic relationship between endosomes, autophagosomes and Lysosomes as well as the transport mechanisms that support the movement of Lysosome precursors in axons. A picture is emerging wherein intermediates in the Lysosome maturation processes that would only exist transiently within the crowded confines of a neuronal cell body are spatially and temporally separated over the extreme distances encountered in axons. Axons may thus offer significant opportunities for the analysis of the mechanisms that control Lysosome biogenesis. Insights from the genetics and pathology of human neurodegenerative diseases furthermore emphasize the importance of efficient axonal transport of Lysosomes and their precursors.
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Lysosomes relax in the cellular suburbs
Journal of Cell Biology, 2016Co-Authors: Swetha Gowrishankar, Shawn M. FergusonAbstract:Lysosomes support cellular homeostasis by degrading macromolecules and recycling nutrients. In this issue, Johnson et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201507112) reveal a heterogeneity in lysosomal pH and degradative ability that correlates with Lysosome subcellular localization, raising questions about the functional implications and mechanisms underlying these observations.
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recruitment of folliculin to Lysosomes supports the amino acid dependent activation of rag gtpases
Journal of Cell Biology, 2013Co-Authors: Constance S Petit, Agnes Roczniakferguson, Shawn M. FergusonAbstract:Birt-Hogg-Dube syndrome, a human disease characterized by fibrofolliculomas (hair follicle tumors) as well as a strong predisposition toward the development of pneumothorax, pulmonary cysts, and renal carcinoma, arises from loss-of-function mutations in the folliculin (FLCN) gene. In this study, we show that FLCN regulates Lysosome function by promoting the mTORC1-dependent phosphorylation and cytoplasmic sequestration of transcription factor EB (TFEB). Our results indicate that FLCN is specifically required for the amino acid–stimulated recruitment of mTORC1 to Lysosomes by Rag GTPases. We further demonstrated that FLCN itself was selectively recruited to the surface of Lysosomes after amino acid depletion and directly bound to RagA via its GTPase domain. FLCN-interacting protein 1 (FNIP1) promotes both the Lysosome recruitment and Rag interactions of FLCN. These new findings define the Lysosome as a site of action for FLCN and indicate a critical role for FLCN in the amino acid–dependent activation of mTOR via its direct interaction with the RagA/B GTPases.
Yamuna Krishnan - One of the best experts on this subject based on the ideXlab platform.
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A DNA nanomachine chemically resolves Lysosomes in live cells
Nature Nanotechnology, 2019Co-Authors: Kaho Leung, Kasturi Chakraborty, Anand Saminathan, Yamuna KrishnanAbstract:Lysosomes are multifunctional, subcellular organelles with roles in plasma membrane repair, autophagy, pathogen degradation and nutrient sensing. Dysfunctional Lysosomes underlie Alzheimer’s disease, Parkinson’s disease and rare lysosomal storage diseases, but their contributions to these pathophysiologies are unclear. Live imaging has revealed Lysosome subpopulations with different physical characteristics including dynamics, morphology or cellular localization. Here, we chemically resolve Lysosome subpopulations using a DNA-based combination reporter that quantitatively images pH and chloride simultaneously in the same Lysosome while retaining single-Lysosome information in live cells. We call this technology two-ion measurement or 2-IM. 2-IM of Lysosomes in primary skin fibroblasts derived from healthy individuals shows two main Lysosome populations, one of which is absent in primary cells derived from patients with Niemann–Pick disease. When patient cells are treated with relevant therapeutics, the second population re-emerges. Chemically resolving Lysosomes by 2-IM could enable decoding the mechanistic underpinnings of lysosomal diseases, monitoring disease progression or evaluating therapeutic efficacy. A DNA-based nanosensor that simultaneously measures pH and chloride concentrations can chemically resolve different subpopulations of Lysosomes in live cells derived from healthy individuals and patients with Niemann–Pick disease.
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subcellular nanorheology reveals lysosomal viscosity as a reporter for lysosomal storage diseases
Nano Letters, 2018Co-Authors: John Devany, Kasturi Chakraborty, Yamuna KrishnanAbstract:We describe a new method to measure viscosity within subcellular organelles of a living cell using nanorheology. We demonstrate proof of concept by measuring viscosity in Lysosomes in multiple cell types and disease models. The Lysosome is an organelle responsible for the breakdown of complex biomolecules. When different lysosomal proteins are defective, they are unable to break down specific biological substrates, which get stored within the Lysosome, causing about 70 fatal diseases called lysosomal storage disorders (LSDs). Although the buildup of storage material is critical to the pathology of these diseases, methods to monitor cargo accumulation in the Lysosome are lacking for most LSDs. Using passive particle tracking nanorheology and fluorescence recovery after photobleaching, we report that viscosity in the Lysosome increases significantly during cargo accumulation in several LSD models. In a mammalian cell culture model of Niemann Pick C, lysosomal viscosity directly correlates with the levels of...
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High lumenal chloride in the Lysosome is critical for Lysosome function
eLife, 2017Co-Authors: Kasturi Chakraborty, Kaho Leung, Yamuna KrishnanAbstract:In cells, worn out proteins and other unnecessary materials are sent to small compartments called Lysosomes to be broken down and recycled. Lysosomes contain many different proteins including some that break down waste material into recyclable fragments and others that transport the fragments out of the Lysosome. If any of these proteins do not work, waste products build up and cause disease. There are around 70 such lysosomal storage diseases, each arising from a different lysosomal protein not working correctly. A recently developed “nanodevice” called Clensor can measure the levels of chloride ions inside cells. Clensor is constructed from DNA, and its fluorescence changes when it detects chloride ions. Although chloride ions have many biological roles, chloride ion levels had not been measured inside a living organism. Now, Chakraborty et al. – including some of the researchers who developed Clensor – have used this nanodevice to examine chloride ion levels in the Lysosomes of the roundworm Caenorhabditis elegans. This revealed that the Lysosomes contain high levels of chloride ions. Furthermore, reducing the amount of chloride in the Lysosomes made them worse at breaking down waste. Do Lysosomes affected by Lysosome storage diseases also contain low levels of chloride ions? To find out, Chakraborty et al. used Clensor to study C. elegans worms and mouse and human cells whose Lysosomes accumulate waste products. In all these cases, the levels of chloride in the diseased Lysosomes were much lower than normal. This had a number of effects on how the Lysosomes worked, such as reducing the activity of key lysosomal proteins. Chakraborty et al. also found that Clensor can be used to distinguish between different lysosomal storage diseases. This means that in the future, Clensor (or similar methods that directly measure chloride ion levels in Lysosomes) may be useful not just for research purposes. They may also be valuable for diagnosing lysosomal storage diseases early in infancy that, if left undiagnosed, are fatal.
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High lumenal chloride in the Lysosome is critical for Lysosome function
bioRxiv, 2017Co-Authors: Yamuna Krishnan, Kasturi Chakraborty, Kaho LeungAbstract:Lysosomes are organelles responsible for the breakdown and recycling of cellular machinery. Dysfunctional Lysosomes give rise to lysosomal storage disorders as well as common neurodegenerative diseases. Here, we use a DNA-based, fluorescent chloride reporter to measure lysosomal chloride in Caenorhabditis elegans as well as murine and human cell culture models of lysosomal diseases. We find that the Lysosome is highly enriched in chloride, and that chloride reduction correlates directly with a loss in the degradative function of the Lysosome. In nematodes and mammalian cell culture models of diverse lysosomal disorders, where previously only lysosomal pH dysregulation has been described, massive reduction of lumenal chloride is observed that is ~10 4 -fold greater than the accompanying pH change. Reducing chloride within the Lysosome impacts Ca 2+ release from the Lysosome and impedes the activity of specific lysosomal enzymes indicating a broader role for chloride in lysosomal function.
Juan S Bonifacino - One of the best experts on this subject based on the ideXlab platform.
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a ragulator borc interaction controls Lysosome positioning in response to amino acid availability
Journal of Cell Biology, 2017Co-Authors: Jing Pu, Tal Kerenkaplan, Juan S BonifacinoAbstract:Lysosomes play key roles in the cellular response to amino acid availability. Depletion of amino acids from the medium turns off a signaling pathway involving the Ragulator complex and the Rag guanosine triphosphatases (GTPases), causing release of the inactive mammalian target of rapamycin complex 1 (mTORC1) serine/threonine kinase from the lysosomal membrane. Decreased phosphorylation of mTORC1 substrates inhibits protein synthesis while activating autophagy. Amino acid depletion also causes clustering of Lysosomes in the juxtanuclear area of the cell, but the mechanisms responsible for this phenomenon are poorly understood. Herein we show that Ragulator directly interacts with BLOC-1–related complex (BORC), a multi-subunit complex previously found to promote Lysosome dispersal through coupling to the small GTPase Arl8 and the kinesins KIF1B and KIF5B. Interaction with Ragulator exerts a negative regulatory effect on BORC that is independent of mTORC1 activity. Amino acid depletion strengthens this interaction, explaining the redistribution of Lysosomes to the juxtanuclear area. These findings thus demonstrate that amino acid availability controls Lysosome positioning through Ragulator-dependent, but mTORC1-independent, modulation of BORC.
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mechanisms and functions of Lysosome positioning
Journal of Cell Science, 2016Co-Authors: Jing Pu, Carlos M Guardia, Tal Kerenkaplan, Juan S BonifacinoAbstract:ABSTRACT Lysosomes have been classically considered terminal degradative organelles, but in recent years they have been found to participate in many other cellular processes, including killing of intracellular pathogens, antigen presentation, plasma membrane repair, cell adhesion and migration, tumor invasion and metastasis, apoptotic cell death, metabolic signaling and gene regulation. In addition, Lysosome dysfunction has been shown to underlie not only rare Lysosome storage disorders but also more common diseases, such as cancer and neurodegeneration. The involvement of Lysosomes in most of these processes is now known to depend on the ability of Lysosomes to move throughout the cytoplasm. Here, we review recent findings on the mechanisms that mediate the motility and positioning of Lysosomes, and the importance of Lysosome dynamics for cell physiology and pathology.
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borc a multisubunit complex that regulates Lysosome positioning
Developmental Cell, 2015Co-Authors: Jing Pu, Christina Schindler, Michal Jarnik, Peter S Backlund, Juan S BonifacinoAbstract:Summary The positioning of Lysosomes within the cytoplasm is emerging as a critical determinant of many lysosomal functions. Here we report the identification of a multisubunit complex named BORC that regulates Lysosome positioning. BORC comprises eight subunits, some of which are shared with the BLOC-1 complex involved in the biogenesis of Lysosome-related organelles, and the others of which are products of previously uncharacterized open reading frames. BORC associates peripherally with the lysosomal membrane, where it functions to recruit the small GTPase Arl8. This initiates a chain of interactions that promotes the kinesin-dependent movement of Lysosomes toward the plus ends of microtubules in the peripheral cytoplasm. Interference with BORC or other components of this pathway results in collapse of the lysosomal population into the pericentriolar region. In turn, this causes reduced cell spreading and migration, highlighting the importance of BORC-dependent centrifugal transport for non-degradative functions of Lysosomes.
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Lysosome-related organelles
The FASEB Journal, 2000Co-Authors: Esteban C. Dell'angelica, Chris Mullins, Steve Caplan, Juan S BonifacinoAbstract:Lysosomes are membrane-bound cytoplasmic organelles involved in intracellular protein degradation. They contain an assortment of soluble acid-dependent hydrolases and a set of highly glycosylated integral membrane proteins. Most of the properties of Lysosomes are shared with a group of cell type-specific compartments referred to as ‘Lysosome-related organelles’, which include melanosomes, lytic granules, MHC class II compartments, platelet-dense granules, basophil granules, azurophil granules, and Drosophila pigment granules. In addition to lysosomal proteins, these organelles contain cell type-specific components that are responsible for their specialized functions. Abnormalities in both Lysosomes and Lysosome-related organelles have been observed in human genetic diseases such as the Chediak-Higashi and Hermansky-Pudlak syndromes, further demonstrating the close relationship between these organelles. Identification of genes mutated in these human diseases, as well as in mouse and Drosophila pigmentation...
Chonglin Yang - One of the best experts on this subject based on the ideXlab platform.
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cdk4 6 regulate Lysosome biogenesis through tfeb tfe3
Journal of Cell Biology, 2020Co-Authors: Youli Jian, Niya Wang, Hejiang Zhou, Xiahe Huang, Jinglin Li, Meng Xu, Lin Xu, Qian Li, Ying Wang, Chonglin YangAbstract:Lysosomes are degradation and signaling organelles that adapt their biogenesis to meet many different cellular demands; however, it is unknown how Lysosomes change their numbers for cell division. Here, we report that the cyclin-dependent kinases CDK4/6 regulate Lysosome biogenesis during the cell cycle. Chemical or genetic inactivation of CDK4/6 increases lysosomal numbers by activating the Lysosome and autophagy transcription factors TFEB and TFE3. CDK4/6 interact with and phosphorylate TFEB/TFE3 in the nucleus, thereby inactivating them by promoting their shuttling to the cytoplasm. During the cell cycle, Lysosome numbers increase in S and G2/M phases when cyclin D turnover diminishes CDK4/6 activity. These findings not only uncover the molecular events that direct the nuclear export of TFEB/TFE3, but also suggest a mechanism that controls Lysosome biogenesis in the cell cycle. CDK4/6 inhibitors promote autophagy and Lysosome-dependent degradation, which has important implications for the therapy of cancer and Lysosome-related disorders.
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an ecm to nucleus signaling pathway activates Lysosomes for c elegans larval development
Developmental Cell, 2020Co-Authors: Chonglin Yang, Meijiao Li, Rui Miao, Qianqian Zhang, Xiaochen WangAbstract:Summary Lysosomes degrade macromolecular cargos, recycle catabolites, and serve as signaling platforms to maintain cell homeostasis, but their role at the tissue level is unclear. Here, we investigate Lysosome regulation and function during C. elegans molting, a specialized extracellular matrix (ECM) remodeling process essential for larval development. We found that Lysosomes are specifically activated in the epidermis at molt when the apical ECM (cuticle) is being replaced. Impaired Lysosome function affects endocytic cargo degradation, suppresses elevated protein synthesis at molt, and causes molting defects. Disturbance of ECM-epidermis attachments triggers lysosomal activation and induces expression of the vacuolar H+-ATPase (V-ATPase), which is mediated by the GATA transcription factor ELT-3 and the STAT family protein STA-2. Our study reveals an ECM-to-nucleus signaling pathway that activates Lysosomes to facilitate ECM remodeling essential for larval development.
Youli Jian - One of the best experts on this subject based on the ideXlab platform.
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cdk4 6 regulate Lysosome biogenesis through tfeb tfe3
Journal of Cell Biology, 2020Co-Authors: Youli Jian, Niya Wang, Hejiang Zhou, Xiahe Huang, Jinglin Li, Meng Xu, Lin Xu, Qian Li, Ying Wang, Chonglin YangAbstract:Lysosomes are degradation and signaling organelles that adapt their biogenesis to meet many different cellular demands; however, it is unknown how Lysosomes change their numbers for cell division. Here, we report that the cyclin-dependent kinases CDK4/6 regulate Lysosome biogenesis during the cell cycle. Chemical or genetic inactivation of CDK4/6 increases lysosomal numbers by activating the Lysosome and autophagy transcription factors TFEB and TFE3. CDK4/6 interact with and phosphorylate TFEB/TFE3 in the nucleus, thereby inactivating them by promoting their shuttling to the cytoplasm. During the cell cycle, Lysosome numbers increase in S and G2/M phases when cyclin D turnover diminishes CDK4/6 activity. These findings not only uncover the molecular events that direct the nuclear export of TFEB/TFE3, but also suggest a mechanism that controls Lysosome biogenesis in the cell cycle. CDK4/6 inhibitors promote autophagy and Lysosome-dependent degradation, which has important implications for the therapy of cancer and Lysosome-related disorders.
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CDK4/6 regulate Lysosome biogenesis through TFEB/TFE3.
The Journal of cell biology, 2020Co-Authors: Youli Jian, Niya Wang, Hejiang Zhou, Xiahe Huang, Jinglin Li, Meng Xu, Qian Li, Lin XuAbstract:Lysosomes are degradation and signaling organelles that adapt their biogenesis to meet many different cellular demands; however, it is unknown how Lysosomes change their numbers for cell division. Here, we report that the cyclin-dependent kinases CDK4/6 regulate Lysosome biogenesis during the cell cycle. Chemical or genetic inactivation of CDK4/6 increases lysosomal numbers by activating the Lysosome and autophagy transcription factors TFEB and TFE3. CDK4/6 interact with and phosphorylate TFEB/TFE3 in the nucleus, thereby inactivating them by promoting their shuttling to the cytoplasm. During the cell cycle, Lysosome numbers increase in S and G2/M phases when cyclin D turnover diminishes CDK4/6 activity. These findings not only uncover the molecular events that direct the nuclear export of TFEB/TFE3, but also suggest a mechanism that controls Lysosome biogenesis in the cell cycle. CDK4/6 inhibitors promote autophagy and Lysosome-dependent degradation, which has important implications for the therapy of cancer and Lysosome-related disorders.
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protein kinase c controls Lysosome biogenesis independently of mtorc1
Nature Cell Biology, 2016Co-Authors: Yang Li, Youli Jian, Xiahe Huang, Meng Xu, Xiao Ding, Zhiqin Song, Lianwan Chen, Xin Wang, Guihua Tang, Changyong TangAbstract:Lysosomes respond to environmental cues by controlling their own biogenesis, but the underlying mechanisms are poorly understood. Here we describe a protein kinase C (PKC)-dependent and mTORC1-independent mechanism for regulating Lysosome biogenesis, which provides insights into previously reported effects of PKC on Lysosomes. By identifying Lysosome-inducing compounds we show that PKC couples activation of the TFEB transcription factor with inactivation of the ZKSCAN3 transcriptional repressor through two parallel signalling cascades. Activated PKC inactivates GSK3β, leading to reduced phosphorylation, nuclear translocation and activation of TFEB, while PKC activates JNK and p38 MAPK, which phosphorylate ZKSCAN3, leading to its inactivation by translocation out of the nucleus. PKC activation may therefore mediate lysosomal adaptation to many extracellular cues. PKC activators facilitate clearance of aggregated proteins and lipid droplets in cell models and ameliorate amyloid β plaque formation in APP/PS1 mouse brains. Thus, PKC activators are viable treatment options for Lysosome-related disorders.
