1
|
Peng H, Wang L, Gao Y, Liu H, Lin G, Kong Y, Xu P, Liu H, Yuan Q, Liu H, Song L, Yang T, Wu H. DMXL2 Is Required for Endocytosis and Recycling of Synaptic Vesicles in Auditory Hair Cells. J Neurosci 2024; 44:e1405232024. [PMID: 39147590 PMCID: PMC11411588 DOI: 10.1523/jneurosci.1405-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 07/10/2024] [Accepted: 08/04/2024] [Indexed: 08/17/2024] Open
Abstract
Ribbon synapses of inner hair cells (IHCs) are uniquely designed for ultrafast and indefatigable neurotransmission of the sound. The molecular machinery ensuring the efficient, compensatory recycling of the synaptic vesicles (SVs), however, remains elusive. This study showed that hair cell knock-out of murine Dmxl2, whose human homolog is responsible for nonsyndromic sensorineural hearing loss DFNA71, resulted in auditory synaptopathy by impairing synaptic endocytosis and recycling. The mutant mice in the C57BL/6J background of either sex had mild hearing loss with severely diminished wave I amplitude of the auditory brainstem response. Membrane capacitance measurements of the IHCs revealed deficiency in sustained synaptic exocytosis and endocytic membrane retrieval. Consistent with the electrophysiological findings, 3D electron microscopy reconstruction showed reduced reserve pool of SVs and endocytic compartments, while the membrane-proximal and ribbon-associated vesicles remain intact. Our results propose an important role of DMXL2 in hair cell endocytosis and recycling of the SVs.
Collapse
Affiliation(s)
- Hu Peng
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200023, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai 200125, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China
- Department of Otolaryngology-Head and Neck Surgery, Changzheng Hospital, Naval Medical University, Shanghai 200003, China
| | - Longhao Wang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200023, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai 200125, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China
| | - Yunge Gao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200023, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai 200125, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China
| | - Huihui Liu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200023, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai 200125, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China
| | - Guotong Lin
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200023, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai 200125, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China
| | - Yu Kong
- Institute of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Pengcheng Xu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200023, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai 200125, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China
| | - Hongchao Liu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200023, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai 200125, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China
| | - Qingyue Yuan
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200023, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai 200125, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China
| | - Huanhai Liu
- Department of Otolaryngology-Head and Neck Surgery, Changzheng Hospital, Naval Medical University, Shanghai 200003, China
| | - Lei Song
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200023, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai 200125, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China
| | - Tao Yang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200023, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai 200125, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China
| | - Hao Wu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200023, China
- Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai 200125, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China
| |
Collapse
|
2
|
Bassi I, Grunspan M, Hen G, Ravichandran KA, Moshe N, Gutierrez-Miranda L, Safriel SR, Kostina D, Shen A, Ruiz de Almodovar C, Yaniv K. Endolysosomal dysfunction in radial glia progenitor cells leads to defective cerebral angiogenesis and compromised blood-brain barrier integrity. Nat Commun 2024; 15:8158. [PMID: 39289367 PMCID: PMC11408700 DOI: 10.1038/s41467-024-52365-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 09/04/2024] [Indexed: 09/19/2024] Open
Abstract
The neurovascular unit (NVU) is a complex multicellular structure that helps maintain cerebral homeostasis and blood-brain barrier (BBB) integrity. While extensive evidence links NVU alterations to cerebrovascular diseases and neurodegeneration, the underlying molecular mechanisms remain unclear. Here, we use zebrafish embryos carrying a mutation in Scavenger Receptor B2, a highly conserved endolysosomal protein expressed predominantly in Radial Glia Cells (RGCs), to investigate the interplay among different NVU components. Through live imaging and genetic manipulations, we demonstrate that compromised acidification of the endolysosomal compartment in mutant RGCs leads to impaired Notch3 signaling, thereby inducing excessive neurogenesis and reduced glial differentiation. We further demonstrate that alterations to the neuron/glia balance result in impaired VEGF and Wnt signaling, leading to severe vascular defects, hemorrhages, and a leaky BBB. Altogether, our findings provide insights into NVU formation and function and offer avenues for investigating diseases involving white matter defects and vascular abnormalities.
Collapse
Affiliation(s)
- Ivan Bassi
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Moshe Grunspan
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Gideon Hen
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Kishore A Ravichandran
- Institute for Neurovascular Cell Biology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Noga Moshe
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Laura Gutierrez-Miranda
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Stav R Safriel
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Daria Kostina
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Amitay Shen
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Carmen Ruiz de Almodovar
- Institute for Neurovascular Cell Biology, Medical Faculty, University of Bonn, Bonn, Germany
- Schlegel Chair for Neurovascular Cell Biology, University of Bonn, Bonn, Germany
| | - Karina Yaniv
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel.
| |
Collapse
|
3
|
Falace A, Volpedo G, Scala M, Zara F, Striano P, Fassio A. V-ATPase Dysfunction in the Brain: Genetic Insights and Therapeutic Opportunities. Cells 2024; 13:1441. [PMID: 39273013 PMCID: PMC11393946 DOI: 10.3390/cells13171441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2024] [Revised: 08/23/2024] [Accepted: 08/25/2024] [Indexed: 09/15/2024] Open
Abstract
Vacuolar-type ATPase (v-ATPase) is a multimeric protein complex that regulates H+ transport across membranes and intra-cellular organelle acidification. Catabolic processes, such as endocytic degradation and autophagy, strictly rely on v-ATPase-dependent luminal acidification in lysosomes. The v-ATPase complex is expressed at high levels in the brain and its impairment triggers neuronal dysfunction and neurodegeneration. Due to their post-mitotic nature and highly specialized function and morphology, neurons display a unique vulnerability to lysosomal dyshomeostasis. Alterations in genes encoding subunits composing v-ATPase or v-ATPase-related proteins impair brain development and synaptic function in animal models and underlie genetic diseases in humans, such as encephalopathies, epilepsy, as well as neurodevelopmental, and degenerative disorders. This review presents the genetic and functional evidence linking v-ATPase subunits and accessory proteins to various brain disorders, from early-onset developmental epileptic encephalopathy to neurodegenerative diseases. We highlight the latest emerging therapeutic strategies aimed at mitigating lysosomal defects associated with v-ATPase dysfunction.
Collapse
Affiliation(s)
- Antonio Falace
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Greta Volpedo
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 16132 Genoa, Italy
| | - Marcello Scala
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 16132 Genoa, Italy
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Federico Zara
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 16132 Genoa, Italy
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Pasquale Striano
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 16132 Genoa, Italy
| | - Anna Fassio
- Department of Experimental Medicine, University of Genoa, 16132 Genoa, Italy
- IRCCS, Ospedale Policlinico San Martino, 16132 Genoa, Italy
| |
Collapse
|
4
|
Hashmi F, Kane PM. V-ATPase Disassembly at the Yeast Lysosome-Like Vacuole Is a Phenotypic Driver of Lysosome Dysfunction in Replicative Aging. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.23.604825. [PMID: 39091794 PMCID: PMC11291124 DOI: 10.1101/2024.07.23.604825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Declines in lysosomal acidification and function with aging are observed in organisms ranging from yeast to humans. V-ATPases play a central role in organelle acidification and V-ATPase activity is regulated by reversible disassembly in many different settings. Using the yeast Saccharomyces cerevisiae as a replicative aging model, we demonstrate that V-ATPases disassemble into their V1 and V0 subcomplexes in aging cells, with release of V1 subunit C (Vma5) from the lysosome-like vacuole into the cytosol. Disassembly is observed after ≥5 cell divisions and results in overall vacuole alkalinization. Caloric restriction, an established mechanism for reversing many age-related outcomes, prevents V-ATPase disassembly in older cells and preserves vacuolar pH homeostasis. Reversible disassembly is controlled in part by the activity of two opposing and conserved factors, the RAVE complex and Oxr1. The RAVE complex promotes V-ATPase assembly and a rav1Δ mutant shortens replicative lifespan; Oxr1 promotes disassembly and an oxr1Δ mutation extends lifespan. Importantly, the level of Rav2, a key subunit of the RAVE complex, declines in aged cells. These data indicate that reduced V-ATPase assembly contributes to the loss of lysosome acidification with age, which affects replicative lifespan.
Collapse
Affiliation(s)
- Fiza Hashmi
- Department of Biochemistry and Molecular Biology , SUNY Upstate Medical University, Syracuse, NY USA
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology , SUNY Upstate Medical University, Syracuse, NY USA
| |
Collapse
|
5
|
Davis GH, Zaya A, Pearce MMP. Impairment of the Glial Phagolysosomal System Drives Prion-Like Propagation in a Drosophila Model of Huntington's Disease. J Neurosci 2024; 44:e1256232024. [PMID: 38589228 PMCID: PMC11097281 DOI: 10.1523/jneurosci.1256-23.2024] [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: 07/06/2023] [Revised: 01/31/2024] [Accepted: 02/26/2024] [Indexed: 04/10/2024] Open
Abstract
Protein misfolding, aggregation, and spread through the brain are primary drivers of neurodegenerative disease pathogenesis. Phagocytic glia are responsible for regulating the load of pathological proteins in the brain, but emerging evidence suggests that glia may also act as vectors for aggregate spread. Accumulation of protein aggregates could compromise the ability of glia to eliminate toxic materials from the brain by disrupting efficient degradation in the phagolysosomal system. A better understanding of phagocytic glial cell deficiencies in the disease state could help to identify novel therapeutic targets for multiple neurological disorders. Here, we report that mutant huntingtin (mHTT) aggregates impair glial responsiveness to injury and capacity to degrade neuronal debris in male and female adult Drosophila expressing the gene that causes Huntington's disease (HD). mHTT aggregate formation in neurons impairs engulfment and clearance of injured axons and causes accumulation of phagolysosomes in glia. Neuronal mHTT expression induces upregulation of key innate immunity and phagocytic genes, some of which were found to regulate mHTT aggregate burden in the brain. A forward genetic screen revealed Rab10 as a novel component of Draper-dependent phagocytosis that regulates mHTT aggregate transmission from neurons to glia. These data suggest that glial phagocytic defects enable engulfed mHTT aggregates to evade lysosomal degradation and acquire prion-like characteristics. Together, our findings uncover new mechanisms that enhance our understanding of the beneficial and harmful effects of phagocytic glia in HD and other neurodegenerative diseases.
Collapse
Affiliation(s)
- Graham H Davis
- Department of Biological and Biomedical Sciences, Rowan University, Glassboro, New Jersey 08028
- Department of Biology, Saint Joseph's University, Philadelphia, Pennsylvania 19131
- Department of Biological Sciences, University of the Sciences, Philadelphia, Pennsylvania 19104
| | - Aprem Zaya
- Department of Biological Sciences, University of the Sciences, Philadelphia, Pennsylvania 19104
| | - Margaret M Panning Pearce
- Department of Biological and Biomedical Sciences, Rowan University, Glassboro, New Jersey 08028
- Department of Biology, Saint Joseph's University, Philadelphia, Pennsylvania 19131
- Department of Biological Sciences, University of the Sciences, Philadelphia, Pennsylvania 19104
| |
Collapse
|
6
|
Davis GH, Zaya A, Pearce MMP. Impairment of the glial phagolysosomal system drives prion-like propagation in a Drosophila model of Huntington's disease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.04.560952. [PMID: 38370619 PMCID: PMC10871239 DOI: 10.1101/2023.10.04.560952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Protein misfolding, aggregation, and spread through the brain are primary drivers of neurodegenerative diseases pathogenesis. Phagocytic glia are responsible for regulating the load of pathogenic protein aggregates in the brain, but emerging evidence suggests that glia may also act as vectors for aggregate spread. Accumulation of protein aggregates could compromise the ability of glia to eliminate toxic materials from the brain by disrupting efficient degradation in the phagolysosomal system. A better understanding of phagocytic glial cell deficiencies in the disease state could help to identify novel therapeutic targets for multiple neurological disorders. Here, we report that mutant huntingtin (mHTT) aggregates impair glial responsiveness to injury and capacity to degrade neuronal debris in male and female adult Drosophila expressing the gene that causes Huntington's disease (HD). mHTT aggregate formation in neurons impairs engulfment and clearance of injured axons and causes accumulation of phagolysosomes in glia. Neuronal mHTT expression induces upregulation of key innate immunity and phagocytic genes, some of which were found to regulate mHTT aggregate burden in the brain. Finally, a forward genetic screen revealed Rab10 as a novel component of Draper-dependent phagocytosis that regulates mHTT aggregate transmission from neurons to glia. These data suggest that glial phagocytic defects enable engulfed mHTT aggregates to evade lysosomal degradation and acquire prion-like characteristics. Together, our findings reveal new mechanisms that enhance our understanding of the beneficial and potentially harmful effects of phagocytic glia in HD and potentially other neurodegenerative diseases.
Collapse
Affiliation(s)
- Graham H. Davis
- Rowan University, Department of Biological and Biomedical Sciences, Glassboro, NJ 08028
- Saint Joseph’s University, Department of Biology, Philadelphia, PA 19131
- University of the Sciences, Department of Biological Sciences, Philadelphia, PA 19104
| | - Aprem Zaya
- University of the Sciences, Department of Biological Sciences, Philadelphia, PA 19104
| | - Margaret M. Panning Pearce
- Rowan University, Department of Biological and Biomedical Sciences, Glassboro, NJ 08028
- Saint Joseph’s University, Department of Biology, Philadelphia, PA 19131
- University of the Sciences, Department of Biological Sciences, Philadelphia, PA 19104
| |
Collapse
|
7
|
Peterson A, Baskett C, Ratcliff WC, Burnetti A. Transforming yeast into a facultative photoheterotroph via expression of vacuolar rhodopsin. Curr Biol 2024; 34:648-654.e3. [PMID: 38218181 DOI: 10.1016/j.cub.2023.12.044] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 11/03/2023] [Accepted: 12/13/2023] [Indexed: 01/15/2024]
Abstract
Phototrophic metabolism, the capture of light for energy, was a pivotal biological innovation that greatly increased the total energy available to the biosphere. Chlorophyll-based photosynthesis is the most familiar phototrophic metabolism, but retinal-based microbial rhodopsins transduce nearly as much light energy as chlorophyll does,1 via a simpler mechanism, and are found in far more taxonomic groups. Although this system has apparently spread widely via horizontal gene transfer,2,3,4 little is known about how rhodopsin genes (with phylogenetic origins within prokaryotes5,6) are horizontally acquired by eukaryotic cells with complex internal membrane architectures or the conditions under which they provide a fitness advantage. To address this knowledge gap, we sought to determine whether Saccharomyces cerevisiae, a heterotrophic yeast with no known evolutionary history of phototrophy, can function as a facultative photoheterotroph after acquiring a single rhodopsin gene. We inserted a rhodopsin gene from Ustilago maydis,7 which encodes a proton pump localized to the vacuole, an organelle normally acidified via a V-type rotary ATPase, allowing the rhodopsin to supplement heterotrophic metabolism. Probes of the physiology of modified cells show that they can deacidify the cytoplasm using light energy, demonstrating the ability of rhodopsins to ameliorate the effects of starvation and quiescence. Further, we show that yeast-bearing rhodopsins gain a selective advantage when illuminated, proliferating more rapidly than their non-phototrophic ancestor or rhodopsin-bearing yeast cultured in the dark. These results underscore the ease with which rhodopsins may be horizontally transferred even in eukaryotes, providing novel biological function without first requiring evolutionary optimization.
Collapse
Affiliation(s)
- Autumn Peterson
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30309, USA; Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA 30309, USA
| | - Carina Baskett
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30309, USA; Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA 30309, USA
| | - William C Ratcliff
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30309, USA; Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA 30309, USA.
| | - Anthony Burnetti
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30309, USA; Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA 30309, USA.
| |
Collapse
|
8
|
Feizy N, Leuchtenberg SF, Steiner C, Würtz B, Fliegner L, Huber A. In vivo identification of Drosophila rhodopsin interaction partners by biotin proximity labeling. Sci Rep 2024; 14:1986. [PMID: 38263196 PMCID: PMC10805788 DOI: 10.1038/s41598-024-52041-3] [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: 10/12/2023] [Accepted: 01/12/2024] [Indexed: 01/25/2024] Open
Abstract
Proteins exert their function through protein-protein interactions. In Drosophila, G protein-coupled receptors like rhodopsin (Rh1) interact with a G protein to activate visual signal transduction and with arrestins to terminate activation. Also, membrane proteins like Rh1 engage in protein-protein interactions during folding within the endoplasmic reticulum, during their vesicular transport and upon removal from the cell surface and degradation. Here, we expressed a Rh1-TurboID fusion protein (Rh1::TbID) in Drosophila photoreceptors to identify in vivo Rh1 interaction partners by biotin proximity labeling. We show that Rh1::TbID forms a functional rhodopsin that mediates biotinylation of arrestin 2 in conditions where arrestin 2 interacts with rhodopsin. We also observed biotinylation of Rh1::TbID and native Rh1 as well as of most visual signal transduction proteins. These findings indicate that the signaling components in the rhabdomere approach rhodopsin closely, within a range of ca. 10 nm. Furthermore, we have detected proteins engaged in the maturation of rhodopsin and elements responsible for the trafficking of membrane proteins, resembling potential interaction partners of Rh1. Among these are chaperons of the endoplasmic reticulum, proteins involved in Clathrin-mediated endocytosis as well as previously unnoticed contributors to rhodopsin transportation, such as Rab32, Vap33, or PIP82.
Collapse
Affiliation(s)
- Nilofar Feizy
- Department of Biochemistry, Institute of Biology, University of Hohenheim, Stuttgart, Germany
| | | | - Christine Steiner
- Department of Biochemistry, Institute of Biology, University of Hohenheim, Stuttgart, Germany
| | - Berit Würtz
- Mass Spectrometry Unit, Core Facility Hohenheim, University of Hohenheim, Stuttgart, Germany
| | - Leo Fliegner
- Department of Biochemistry, Institute of Biology, University of Hohenheim, Stuttgart, Germany
| | - Armin Huber
- Department of Biochemistry, Institute of Biology, University of Hohenheim, Stuttgart, Germany.
| |
Collapse
|
9
|
Jiang YT, Yang LH, Zheng JX, Geng XC, Bai YX, Wang YC, Xue HW, Lin WH. Vacuolar H +-ATPase and BZR1 form a feedback loop to regulate the homeostasis of BR signaling in Arabidopsis. MOLECULAR PLANT 2023; 16:1976-1989. [PMID: 37837193 DOI: 10.1016/j.molp.2023.10.007] [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: 05/27/2023] [Revised: 09/29/2023] [Accepted: 10/10/2023] [Indexed: 10/15/2023]
Abstract
Brassinosteroid (BR) is a vital plant hormone that regulates plant growth and development. BRASSINAZOLE RESISTANT 1 (BZR1) is a key transcription factor in BR signaling, and its nucleocytoplasmic localization is crucial for BR signaling. However, the mechanisms that regulate BZR1 nucleocytoplasmic distribution and thus the homeostasis of BR signaling remain largely unclear. The vacuole is the largest organelle in mature plant cells and plays a key role in maintenance of cellular pH, storage of intracellular substances, and transport of ions. In this study, we uncovered a novel mechanism of BR signaling homeostasis regulated by the vacuolar H+-ATPase (V-ATPase) and BZR1 feedback loop. Our results revealed that the vha-a2 vha-a3 mutant (vha2, lacking V-ATPase activity) exhibits enhanced BR signaling with increased total amount of BZR1, nuclear-localized BZR1, and the ratio of BZR1/phosphorylated BZR1 in the nucleus. Further biochemical assays revealed that VHA-a2 and VHA-a3 of V-ATPase interact with the BZR1 protein through a domain that is conserved across multiple species. VHA-a2 and VHA-a3 negatively regulate BR signaling by interacting with BZR1 and promoting its retention in the tonoplast. Interestingly, a series of molecular analyses demonstrated that nuclear-localized BZR1 could bind directly to specific motifs in the promoters of VHA-a2 and VHA-a3 to promote their expression. Taken together, these results suggest that V-ATPase and BZR1 may form a feedback regulatory loop to maintain the homeostasis of BR signaling in Arabidopsis, providing new insights into vacuole-mediated regulation of hormone signaling.
Collapse
Affiliation(s)
- Yu-Tong Jiang
- School of Life Sciences and Biotechnology, The Joint International Research Laboratory of Metabolic & Developmental Sciences, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Collaborative Innovation Center of Agri-Seeds, Joint Center for Single Cell Biology, Shanghai 200240, China; School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Lu-Han Yang
- School of Life Sciences and Biotechnology, The Joint International Research Laboratory of Metabolic & Developmental Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ji-Xuan Zheng
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xian-Chen Geng
- School of Life Sciences and Biotechnology, The Joint International Research Laboratory of Metabolic & Developmental Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yu-Xuan Bai
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yu-Chen Wang
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Hong-Wei Xue
- Shanghai Collaborative Innovation Center of Agri-Seeds, Joint Center for Single Cell Biology, Shanghai 200240, China; School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Wen-Hui Lin
- School of Life Sciences and Biotechnology, The Joint International Research Laboratory of Metabolic & Developmental Sciences, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Collaborative Innovation Center of Agri-Seeds, Joint Center for Single Cell Biology, Shanghai 200240, China.
| |
Collapse
|
10
|
Hounjet J, Groot AJ, Piepers JP, Kranenburg O, Zwijnenburg DA, Rapino FA, Koster JB, Kampen KR, Vooijs MA. Iron-responsive element of Divalent metal transporter 1 (Dmt1) controls Notch-mediated cell fates. FEBS J 2023; 290:5811-5834. [PMID: 37646174 DOI: 10.1111/febs.16946] [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: 02/14/2023] [Revised: 07/12/2023] [Accepted: 08/29/2023] [Indexed: 09/01/2023]
Abstract
Notch receptor activation is regulated by the intramembrane protease γ-secretase, which cleaves and liberates the Notch intracellular domain (Nicd) that regulates gene transcription. While γ-secretase cleavage is necessary, we demonstrate it is insufficient for Notch activation and requires vesicular trafficking. Here, we report Divalent metal transporter 1 (Dmt1, Slc11A2) as a novel and essential regulator of Notch signalling. Dmt1-deficient cells are defective in Notch signalling and have perturbed endolysosomal trafficking and function. Dmt1 encodes for two isoforms, with and without an iron response element (ire). We show that isoform-specific silencing of Dmt1-ire and Dmt1+ire has opposite consequences on Notch-dependent cell fates in cell lines and intestinal organoids. Loss of Dmt1-ire suppresses Notch activation and promotes differentiation, whereas loss of Dmt1+ire causes Notch activation and maintains stem-progenitor cell fates. Dmt1 isoform expression correlates with Notch and Wnt signalling in Apc-deficient intestinal organoids and human colorectal cancers. Consistently, Dmt1-ire silencing induces Notch-dependent differentiation in colorectal cancer cells. These data identify Dmt1 isoforms as binary switches controlling Notch cell fate decisions in normal and tumour cells.
Collapse
Affiliation(s)
- Judith Hounjet
- Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Arjan J Groot
- Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Jolanda P Piepers
- Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Onno Kranenburg
- Lab Translational Oncology, Division Imaging and Cancer, University Medical Center Utrecht, The Netherlands
| | - Danny A Zwijnenburg
- Center for Experimental and Molecular Medicine, Amsterdam UMC Location University of Amsterdam, The Netherlands
| | - Francesca A Rapino
- Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands
- Department of Pharmacy, Giga Stem Cells, University of Liege, Belgium
| | - Jan B Koster
- Center for Experimental and Molecular Medicine, Amsterdam UMC Location University of Amsterdam, The Netherlands
| | - Kim R Kampen
- Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Marc A Vooijs
- Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands
| |
Collapse
|
11
|
Hermosilla Aguayo V, Martin P, Tian N, Zheng J, Aho R, Losa M, Selleri L. ESCRT-dependent control of craniofacial morphogenesis with concomitant perturbation of NOTCH signaling. Dev Biol 2023; 503:25-42. [PMID: 37573008 DOI: 10.1016/j.ydbio.2023.08.002] [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: 05/12/2023] [Revised: 08/08/2023] [Accepted: 08/09/2023] [Indexed: 08/14/2023]
Abstract
Craniofacial development is orchestrated by transcription factor-driven regulatory networks, epigenetic modifications, and signaling pathways. Signaling molecules and their receptors rely on endo-lysosomal trafficking to prevent accumulation on the plasma membrane. ESCRT (Endosomal Sorting Complexes Required for Transport) machinery is recruited to endosomal membranes enabling degradation of such endosomal cargoes. Studies in vitro and in invertebrate models established the requirements of the ESCRT machinery in membrane remodeling, endosomal trafficking, and lysosomal degradation of activated membrane receptors. However, investigations during vertebrate development have been scarce. By ENU-induced mutagenesis, we isolated a mouse line, Vps25ENU/ENU, carrying a hypomorphic allele of the ESCRT-II component Vps25, with craniofacial anomalies resembling features of human congenital syndromes. Here, we assessed the spatiotemporal dynamics of Vps25 and additional ESCRT-encoding genes during murine development. We show that these genes are ubiquitously expressed although enriched in discrete domains of the craniofacial complex, heart, and limbs. ESCRT-encoding genes, including Vps25, are expressed in both cranial neural crest-derived mesenchyme and epithelium. Unlike constitutive ESCRT mutants, Vps25ENU/ENU embryos display late lethality. They exhibit hypoplastic lower jaw, stunted snout, dysmorphic ear pinnae, and secondary palate clefting. Thus, we provide the first evidence for critical roles of ESCRT-II in craniofacial morphogenesis and report perturbation of NOTCH signaling in craniofacial domains of Vps25ENU/ENU embryos. Given the known roles of NOTCH signaling in the developing cranium, and notably the lower jaw, we propose that the NOTCH pathway partly mediates the craniofacial defects of Vps25ENU/ENU mouse embryos.
Collapse
Affiliation(s)
- Viviana Hermosilla Aguayo
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine & Stem Cell Research, Dept of Orofacial Sciences and Dept of Anatomy, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Peter Martin
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine & Stem Cell Research, Dept of Orofacial Sciences and Dept of Anatomy, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Nuo Tian
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine & Stem Cell Research, Dept of Orofacial Sciences and Dept of Anatomy, University of California, San Francisco, San Francisco, CA 94143, USA
| | - James Zheng
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine & Stem Cell Research, Dept of Orofacial Sciences and Dept of Anatomy, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Robert Aho
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine & Stem Cell Research, Dept of Orofacial Sciences and Dept of Anatomy, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Marta Losa
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine & Stem Cell Research, Dept of Orofacial Sciences and Dept of Anatomy, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Licia Selleri
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine & Stem Cell Research, Dept of Orofacial Sciences and Dept of Anatomy, University of California, San Francisco, San Francisco, CA 94143, USA.
| |
Collapse
|
12
|
Kha CX, Nava I, Tseng KAS. V-ATPase Regulates Retinal Progenitor Cell Proliferation During Eye Regrowth in Xenopus. J Ocul Pharmacol Ther 2023; 39:499-508. [PMID: 36867156 PMCID: PMC10616942 DOI: 10.1089/jop.2022.0085] [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: 07/06/2022] [Accepted: 11/29/2022] [Indexed: 03/04/2023] Open
Abstract
Purpose: The induction of retinal progenitor cell (RPC) proliferation is a strategy that holds promise for alleviating retinal degeneration. However, the mechanisms that can stimulate RPC proliferation during repair remain unclear. Xenopus tailbud embryos successfully regrow functional eyes within 5 days after ablation, and this process requires increased RPC proliferation. This model facilitates identification of mechanisms that can drive in vivo reparative RPC proliferation. This study assesses the role of the essential H+ pump, V-ATPase, in promoting stem cell proliferation. Methods: Pharmacological and molecular loss of function studies were performed to determine the requirement for V-ATPase during embryonic eye regrowth. The resultant eye phenotypes were examined using histology and antibody markers. Misexpression of a yeast H+ pump was used to test whether the requirement for V-ATPase in regrowth is dependent on its H+ pump function. Results: V-ATPase inhibition blocked eye regrowth. Regrowth-incompetent eyes resulting from V-ATPase inhibition contained the normal complement of tissues but were much smaller. V-ATPase inhibition caused a significant reduction in reparative RPC proliferation but did not alter differentiation and patterning. Modulation of V-ATPase activity did not affect apoptosis, a process known to be required for eye regrowth. Finally, increasing H+ pump activity was sufficient to induce regrowth. Conclusions: V-ATPase is required for eye regrowth. These results reveal a key role for V-ATPase in activating regenerative RPC proliferation and expansion during successful eye regrowth.
Collapse
Affiliation(s)
- Cindy X. Kha
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
| | - Iris Nava
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
| | - Kelly Ai-Sun Tseng
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
| |
Collapse
|
13
|
Hanly JJ, Francescutti CM, Loh LS, Corning OBWH, Long DJ, Nakatani MA, Porter AH, Martin A. Genetics of yellow-orange color variation in a pair of sympatric sulphur butterflies. Cell Rep 2023; 42:112820. [PMID: 37481719 DOI: 10.1016/j.celrep.2023.112820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 06/02/2023] [Accepted: 06/29/2023] [Indexed: 07/25/2023] Open
Abstract
Continuous color polymorphisms can serve as a tractable model for the genetic and developmental architecture of traits. Here we investigated continuous color variation in Colias eurytheme and Colias philodice, two species of sulphur butterflies that hybridize in sympatry. Using quantitative trait locus (QTL) analysis and high-throughput color quantification, we found two interacting large-effect loci affecting orange-to-yellow chromaticity. Knockouts of red Malpighian tubules (red), likely involved in endosomal maturation, result in depigmented wing scales. Additionally, the transcription factor bric-a-brac can act as a modulator of orange pigmentation. We also describe the QTL architecture of other continuously varying traits, together supporting a large-X effect model where the genetic control of species-defining traits is enriched on sex chromosomes. This study sheds light on the range of possible genetic architectures that can underpin a continuously varying trait and illustrates the power of using automated measurement to score phenotypes that are not always conspicuous to the human eye.
Collapse
Affiliation(s)
- Joseph J Hanly
- Department of Biological Sciences, The George Washington University, Washington, DC, USA; Smithsonian Tropical Research Institute, Gamboa, Panama.
| | | | - Ling S Loh
- Department of Biological Sciences, The George Washington University, Washington, DC, USA
| | - Olaf B W H Corning
- Department of Biological Sciences, The George Washington University, Washington, DC, USA
| | - Derek J Long
- Department of Biological Sciences, The George Washington University, Washington, DC, USA
| | - Marshall A Nakatani
- Department of Biological Sciences, The George Washington University, Washington, DC, USA
| | - Adam H Porter
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, USA.
| | - Arnaud Martin
- Department of Biological Sciences, The George Washington University, Washington, DC, USA.
| |
Collapse
|
14
|
Dittrich A, Ramesh G, Jung M, Schmitz F. Rabconnectin-3α/DMXL2 Is Locally Enriched at the Synaptic Ribbon of Rod Photoreceptor Synapses. Cells 2023; 12:1665. [PMID: 37371135 DOI: 10.3390/cells12121665] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 06/08/2023] [Accepted: 06/17/2023] [Indexed: 06/29/2023] Open
Abstract
Ribbon synapses reliably transmit synaptic signals over a broad signalling range. Rod photoreceptor ribbon synapses are capable of transmitting signals generated by the absorption of single photons. The high precision of ribbon synapses emphasizes the need for particularly efficient signalling mechanisms. Synaptic ribbons are presynaptic specializations of ribbon synapses and are anchored to the active zone. Synaptic ribbons bind many synaptic vesicles that are delivered to the active zone for continuous and faithful signalling. In the present study we demonstrate with independent antibodies at the light- and electron microscopic level that rabconnectin-3α (RC3α)-alternative name Dmx-like 2 (DMXL2)-is localized to the synaptic ribbons of rod photoreceptor synapses in the mouse retina. In the brain, RC3α-containing complexes are known to interact with important components of synaptic vesicles, including Rab3-activating/inactivating enzymes, priming proteins and the vesicular H+-ATPase that acidifies the synaptic vesicle lumen to promote full neurotransmitter loading. The association of RC3α/DMXL2 with rod synaptic ribbons of the mouse retina could enable these structures to deliver only fully signalling-competent synaptic vesicles to the active zone thus contributing to reliable synaptic communication.
Collapse
Affiliation(s)
- Alina Dittrich
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| | - Girish Ramesh
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
- Institute of Biophysics, Saarland University, 66421 Homburg, Germany
| | - Martin Jung
- Institute of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany
| | - Frank Schmitz
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| |
Collapse
|
15
|
Wang H, Rubinstein JL. CryoEM of V-ATPases: Assembly, disassembly, and inhibition. Curr Opin Struct Biol 2023; 80:102592. [PMID: 37272327 DOI: 10.1016/j.sbi.2023.102592] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 03/13/2023] [Accepted: 03/16/2023] [Indexed: 06/06/2023]
Abstract
Vacuolar-type ATPases (V-ATPases) are responsible for the acidification of intracellular compartments in almost all eukaryotic cells, while in some specialized cells they acidify the extracellular environment. As ubiquitous proton pumps, these large membrane-embedded enzymes are involved in many fundamental cellular processes that require tight control of pH. Consequently, V-ATPase malfunction or aberrant activity has been linked to numerous diseases. In the past ten years, electron cryomicroscopy (cryoEM) of yeast V-ATPases has revealed the architecture and rotary catalytic mechanism of these macromolecular machines. More recently, studies have revealed the structures of V-ATPases in animals and plants, uncovered aspects of how V-ATPases are assembled and regulated by reversible dissociation, and shown how V-ATPase activity can be modulated by proteins and small molecule inhibitors. In this review, we highlight these recent developments.
Collapse
Affiliation(s)
- Hanlin Wang
- Molecular Medicine Program, The Hospital for Sick Children, M5G 0A4, Toronto, Canada; Department of Biochemistry, The University of Toronto, M5G 1L7, Toronto, Canada
| | - John L Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children, M5G 0A4, Toronto, Canada; Department of Biochemistry, The University of Toronto, M5G 1L7, Toronto, Canada; Department of Medical Biophysics, The University of Toronto, M5S 1A8, Toronto, Canada.
| |
Collapse
|
16
|
Barone S, Brooks M, Zahedi K, Holliday LS, Bissler J, Yu JJ, Soleimani M. Identification of an Electrogenic 2Cl -/H + Exchanger, ClC5, as a Chloride-Secreting Transporter Candidate in Kidney Cyst Epithelium in Tuberous Sclerosis. THE AMERICAN JOURNAL OF PATHOLOGY 2023; 193:191-200. [PMID: 36336066 PMCID: PMC9926528 DOI: 10.1016/j.ajpath.2022.10.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/23/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022]
Abstract
Kidney cyst expansion in tuberous sclerosis complex (TSC) or polycystic kidney disease (PKD) requires active secretion of chloride (Cl-) into the cyst lumen. In PKD, Cl- secretion is primarily mediated via the cystic fibrosis transmembrane conductance regulator (CFTR) in principal cells. Kidney cystogenesis in TSC is predominantly composed of type A intercalated cells, which do not exhibit noticeable expression of CFTR. The identity of the Cl--secreting molecule(s) in TSC cyst epithelia remains speculative. RNA-sequencing analysis results were used to examine the expression of FOXi1, the chief regulator of acid base transporters in intercalated cells, along with localization of Cl- channel 5 (ClC5), in various models of TSC. Results from Tsc2+/- mice showed that the expansion of kidney cysts corresponded to the induction of Foxi1 and correlated with the appearance of ClC5 and H+-ATPase on the apical membrane of cyst epithelia. In various mouse models of TSC, Foxi1 was robustly induced in the kidney, and ClC5 and H+-ATPase were expressed on the apical membrane of cyst epithelia. Expression of ClC5 was also detected on the apical membrane of cyst epithelia in humans with TSC but was absent in humans with autosomal dominant PKD or in a mouse model of PKD. These results indicate that ClC5 is expressed on the apical membrane of cyst epithelia and is a likely candidate mediating Cl- secretion into the kidney cyst lumen in TSC.
Collapse
Affiliation(s)
- Sharon Barone
- Research Services, Veterans Health Care Medical Center, Albuquerque, New Mexico; Department of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Marybeth Brooks
- Research Services, Veterans Health Care Medical Center, Albuquerque, New Mexico; Department of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Kamyar Zahedi
- Research Services, Veterans Health Care Medical Center, Albuquerque, New Mexico; Department of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | | | - John Bissler
- Department of Pediatrics, University of Tennessee Health Science Center and Le Bonheur Children's Hospital, Memphis, Tennessee; Department of Pediatrics, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Jane J Yu
- Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Manoocher Soleimani
- Research Services, Veterans Health Care Medical Center, Albuquerque, New Mexico; Department of Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico.
| |
Collapse
|
17
|
Lardelli M. An Alternative View of Familial Alzheimer's Disease Genetics. J Alzheimers Dis 2023; 96:13-39. [PMID: 37718800 DOI: 10.3233/jad-230313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
Probabilistic and parsimony-based arguments regarding available genetics data are used to propose that Hardy and Higgin's amyloid cascade hypothesis is valid but is commonly interpreted too narrowly to support, incorrectly, the primacy of the amyloid-β peptide (Aβ) in driving Alzheimer's disease pathogenesis. Instead, increased activity of the βCTF (C99) fragment of AβPP is the critical pathogenic determinant altered by mutations in the APP gene. This model is consistent with the regulation of APP mRNA translation via its 5' iron responsive element. Similar arguments support that the pathological effects of familial Alzheimer's disease mutations in the genes PSEN1 and PSEN2 are not exerted directly via changes in AβPP cleavage to produce different ratios of Aβ length. Rather, these mutations likely act through effects on presenilin holoprotein conformation and function, and possibly the formation and stability of multimers of presenilin holoprotein and/or of the γ-secretase complex. All fAD mutations in APP, PSEN1, and PSEN2 likely find unity of pathological mechanism in their actions on endolysosomal acidification and mitochondrial function, with detrimental effects on iron homeostasis and promotion of "pseudo-hypoxia" being of central importance. Aβ production is enhanced and distorted by oxidative stress and accumulates due to decreased lysosomal function. It may act as a disease-associated molecular pattern enhancing oxidative stress-driven neuroinflammation during the cognitive phase of the disease.
Collapse
Affiliation(s)
- Michael Lardelli
- Alzheimer's Disease Genetics Laboratory, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| |
Collapse
|
18
|
Tan YZ, Abbas YM, Wu JZ, Wu D, Keon KA, Hesketh GG, Bueler SA, Gingras AC, Robinson CV, Grinstein S, Rubinstein JL. CryoEM of endogenous mammalian V-ATPase interacting with the TLDc protein mEAK-7. Life Sci Alliance 2022; 5:e202201527. [PMID: 35794005 PMCID: PMC9263379 DOI: 10.26508/lsa.202201527] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/17/2022] [Accepted: 06/21/2022] [Indexed: 12/18/2022] Open
Abstract
V-ATPases are rotary proton pumps that serve as signaling hubs with numerous protein binding partners. CryoEM with exhaustive focused classification allowed detection of endogenous proteins associated with porcine kidney V-ATPase. An extra C subunit was found in ∼3% of complexes, whereas ∼1.6% of complexes bound mEAK-7, a protein with proposed roles in dauer formation in nematodes and mTOR signaling in mammals. High-resolution cryoEM of porcine kidney V-ATPase with recombinant mEAK-7 showed that mEAK-7's TLDc domain interacts with V-ATPase's stator, whereas its C-terminal α helix binds V-ATPase's rotor. This crosslink would be expected to inhibit rotary catalysis. However, unlike the yeast TLDc protein Oxr1p, exogenous mEAK-7 does not inhibit V-ATPase and mEAK-7 overexpression in cells does not alter lysosomal or phagosomal pH. Instead, cryoEM suggests that the mEAK-7:V-ATPase interaction is disrupted by ATP-induced rotation of the rotor. Comparison of Oxr1p and mEAK-7 binding explains this difference. These results show that V-ATPase binding by TLDc domain proteins can lead to effects ranging from strong inhibition to formation of labile interactions that are sensitive to the enzyme's activity.
Collapse
Affiliation(s)
- Yong Zi Tan
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, Canada
| | - Yazan M Abbas
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, Canada
| | - Jing Ze Wu
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Di Wu
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK
| | - Kristine A Keon
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, Canada
| | - Geoffrey G Hesketh
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Canada
| | - Stephanie A Bueler
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, Canada
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Carol V Robinson
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK
| | - Sergio Grinstein
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - John L Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
| |
Collapse
|
19
|
Su K, Collins MP, McGuire CM, Alshagawi MA, Alamoudi MK, Li Z, Forgac M. Isoform a4 of the vacuolar ATPase a subunit promotes 4T1-12B breast cancer cell-dependent tumor growth and metastasis in vivo. J Biol Chem 2022; 298:102395. [PMID: 35988642 PMCID: PMC9508560 DOI: 10.1016/j.jbc.2022.102395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 08/11/2022] [Accepted: 08/15/2022] [Indexed: 12/24/2022] Open
Abstract
The vacuolar H+-ATPase (V-ATPase) is an ATP-dependent proton pump that governs the pH of various intracellular compartments and also functions at the plasma membrane in certain cell types, including cancer cells. Membrane targeting of the V-ATPase is controlled by isoforms of subunit a, and we have previously shown that isoforms a3 and a4 are important for the migration and invasion of several breast cancer cell lines in vitro. Using CRISPR-mediated genome editing to selectively disrupt each of the four a subunit isoforms, we also recently showed that a4 is critical to plasma membrane V-ATPase localization, as well as in vitro migration and invasion of 4T1-12B murine breast cancer cells. We now report that a4 is important for the growth of 4T1-12B tumors in vivo. We found that BALB/c mice bearing a4-/- 4T1-12B allografts had significantly smaller tumors than mice in the control group. In addition, we determined that a4-/- allografts showed dramatically reduced metastases to the lung and reduced luminescence intensity of metastases to bone relative to the control group. Taken together, these results suggest that the a4 isoform of the V-ATPase represents a novel potential therapeutic target to limit breast cancer growth and metastasis.
Collapse
Affiliation(s)
- Kevin Su
- Department of Pharmacology and Drug Development, Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts, USA
| | - Michael P Collins
- Department of Cellular, Molecular and Developmental Biology, Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts, USA
| | - Christina M McGuire
- Department of Biochemistry, Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts, USA
| | - Mohammed A Alshagawi
- Department of Pharmacology and Drug Development, Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts, USA
| | - Mariam K Alamoudi
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Zhen Li
- Department of Pharmacology and Drug Development, Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts, USA
| | - Michael Forgac
- Department of Pharmacology and Drug Development, Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts, USA; Department of Cellular, Molecular and Developmental Biology, Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts, USA; Department of Biochemistry, Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts, USA; Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA.
| |
Collapse
|
20
|
Hebert KA, Bonnen MD, Ghebre YT. Proton pump inhibitors and sensitization of cancer cells to radiation therapy. Front Oncol 2022; 12:937166. [PMID: 35992826 PMCID: PMC9388769 DOI: 10.3389/fonc.2022.937166] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 06/30/2022] [Indexed: 12/23/2022] Open
Abstract
This review article outlines six molecular pathways that confer resistance of cancer cells to ionizing radiation, and describes how proton pump inhibitors (PPIs) may be used to overcome radioresistance induced by alteration of one or more of these signaling pathways. The inflammatory, adaptive, hypoxia, DNA damage repair, cell adhesion, and developmental pathways have all been linked to the resistance of cancer cells to ionizing radiation. Here we describe the molecular link between alteration of these pathways in cancer cells and development of resistance to ionizing radiation, and discuss emerging data on the use of PPIs to favorably modify one or more components of these pathways to sensitize cancer cells to ionizing radiation. Understanding the relationship between altered signaling pathways, radioresistance, and biological activity of PPIs may serve as a basis to repurpose PPIs to restore key biological processes that are involved in cancer progression and to sensitize cancer cells to radiation therapy.
Collapse
Affiliation(s)
- Kassidy A. Hebert
- Department of Radiation Oncology, Baylor College of Medicine, Houston, TX, United States
- Interdepartmental Graduate Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX, United States
| | - Mark D. Bonnen
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, Long School of Medicine, San Antonio, TX, United States
| | - Yohannes T. Ghebre
- Department of Radiation Oncology, Baylor College of Medicine, Houston, TX, United States
- Department of Medicine, Section on Pulmonary and Critical Care Medicine, Baylor College of Medicine, Houston, TX, United States
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, United States
- *Correspondence: Yohannes T. Ghebre,
| |
Collapse
|
21
|
Vasanthakumar T, Keon KA, Bueler SA, Jaskolka MC, Rubinstein JL. Coordinated conformational changes in the V 1 complex during V-ATPase reversible dissociation. Nat Struct Mol Biol 2022; 29:430-439. [PMID: 35469063 DOI: 10.1038/s41594-022-00757-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 03/03/2022] [Indexed: 11/10/2022]
Abstract
Vacuolar-type ATPases (V-ATPases) are rotary enzymes that acidify intracellular compartments in eukaryotic cells. These multi-subunit complexes consist of a cytoplasmic V1 region that hydrolyzes ATP and a membrane-embedded VO region that transports protons. V-ATPase activity is regulated by reversible dissociation of the two regions, with the isolated V1 and VO complexes becoming autoinhibited on disassembly and subunit C subsequently detaching from V1. In yeast, assembly of the V1 and VO regions is mediated by the regulator of the ATPase of vacuoles and endosomes (RAVE) complex through an unknown mechanism. We used cryogenic-electron microscopy of yeast V-ATPase to determine structures of the intact enzyme, the dissociated but complete V1 complex and the V1 complex lacking subunit C. On separation, V1 undergoes a dramatic conformational rearrangement, with its rotational state becoming incompatible for reassembly with VO. Loss of subunit C allows V1 to match the rotational state of VO, suggesting how RAVE could reassemble V1 and VO by recruiting subunit C.
Collapse
Affiliation(s)
- Thamiya Vasanthakumar
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Biochemistry, The University of Toronto, Toronto, Ontario, Canada
| | - Kristine A Keon
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, The University of Toronto, Toronto, Ontario, Canada
| | - Stephanie A Bueler
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Michael C Jaskolka
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - John L Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada. .,Department of Biochemistry, The University of Toronto, Toronto, Ontario, Canada. .,Department of Medical Biophysics, The University of Toronto, Toronto, Ontario, Canada.
| |
Collapse
|
22
|
Cuesta-Casanovas L, Delgado-Martínez J, Cornet-Masana JM, Carbó JM, Clément-Demange L, Risueño RM. Lysosome-mediated chemoresistance in acute myeloid leukemia. CANCER DRUG RESISTANCE (ALHAMBRA, CALIF.) 2022; 5:233-244. [PMID: 35582535 PMCID: PMC8992599 DOI: 10.20517/cdr.2021.122] [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: 11/12/2022]
Abstract
Despite the outstanding advances in understanding the biology underlying the pathophysiology of acute myeloid leukemia (AML) and the promising preclinical data published lastly, AML treatment still relies on a classic chemotherapy regimen largely unchanged for the past five decades. Recently, new drugs have been approved for AML, but the real clinical benefit is still under evaluation. Nevertheless, primary refractory and relapse AML continue to represent the main clinical challenge, as the majority of AML patients will succumb to the disease despite achieving a complete remission during the induction phase. As such, treatments for chemoresistant AML represent an unmet need in this disease. Although great efforts have been made to decipher the biological basis for leukemogenesis, the mechanism by which AML cells become resistant to chemotherapy is largely unknown. The identification of the signaling pathways involved in resistance may lead to new combinatory therapies or new therapeutic approaches suitable for this subset of patients. Several mechanisms of chemoresistance have been identified, including drug transporters, key secondary messengers, and metabolic regulators. However, no therapeutic approach targeting chemoresistance has succeeded in clinical trials, especially due to broad secondary effects in healthy cells. Recent research has highlighted the importance of lysosomes in this phenomenon. Lysosomes' key role in resistance to chemotherapy includes the potential to sequester drugs, central metabolic signaling role, and gene expression regulation. These results provide further evidence to support the development of new therapeutic approaches that target lysosomes in AML.
Collapse
Affiliation(s)
- Laia Cuesta-Casanovas
- Josep Carreras Leukaemia Research Institute (IJC), Barcelona 08916, Spain
- Faculty of Biosciences, Autonomous University of Barcelona, Bellaterra (Cerdanyola del Vallès) 08193, Spain
| | - Jennifer Delgado-Martínez
- Josep Carreras Leukaemia Research Institute (IJC), Barcelona 08916, Spain
- Faculty of Pharmacy, University of Barcelona, Barcelona 08028, Spain
| | | | - José M. Carbó
- Leukos Biotech, Muntaner, 383, Barcelona 08036, Spain
| | | | - Ruth M. Risueño
- Josep Carreras Leukaemia Research Institute (IJC), Barcelona 08916, Spain
| |
Collapse
|
23
|
Cho NH, Cheveralls KC, Brunner AD, Kim K, Michaelis AC, Raghavan P, Kobayashi H, Savy L, Li JY, Canaj H, Kim JY, Stewart EM, Gnann C, McCarthy F, Cabrera JP, Brunetti RM, Chhun BB, Dingle G, Hein MY, Huang B, Mehta SB, Weissman JS, Gómez-Sjöberg R, Itzhak DN, Royer LA, Mann M, Leonetti MD. OpenCell: Endogenous tagging for the cartography of human cellular organization. Science 2022; 375:eabi6983. [PMID: 35271311 PMCID: PMC9119736 DOI: 10.1126/science.abi6983] [Citation(s) in RCA: 184] [Impact Index Per Article: 92.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Elucidating the wiring diagram of the human cell is a central goal of the postgenomic era. We combined genome engineering, confocal live-cell imaging, mass spectrometry, and data science to systematically map the localization and interactions of human proteins. Our approach provides a data-driven description of the molecular and spatial networks that organize the proteome. Unsupervised clustering of these networks delineates functional communities that facilitate biological discovery. We found that remarkably precise functional information can be derived from protein localization patterns, which often contain enough information to identify molecular interactions, and that RNA binding proteins form a specific subgroup defined by unique interaction and localization properties. Paired with a fully interactive website (opencell.czbiohub.org), our work constitutes a resource for the quantitative cartography of human cellular organization.
Collapse
Affiliation(s)
| | | | - Andreas-David Brunner
- Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Kibeom Kim
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - André C. Michaelis
- Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | | | | | - Laura Savy
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Jason Y. Li
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Hera Canaj
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | | | | | - Christian Gnann
- Chan Zuckerberg Biohub, San Francisco, CA, USA
- Science for Life Laboratory, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH-Royal Institute of Technology, Stockholm, Sweden
| | | | | | - Rachel M. Brunetti
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA
| | | | - Greg Dingle
- Chan Zuckerberg Initiative, Redwood City, CA, USA
| | | | - Bo Huang
- Chan Zuckerberg Biohub, San Francisco, CA, USA
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
| | | | - Jonathan S. Weissman
- Whitehead Institute, Koch Institute, Howard Hughes Medical Institute, and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA
| | | | | | | | - Matthias Mann
- Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
- NNF Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | |
Collapse
|
24
|
Liu XJ, Liang XY, Guo J, Shi XK, Merzendorfer H, Zhu KY, Zhang JZ. V-ATPase subunit a is required for survival and midgut development of Locusta migratoria. INSECT MOLECULAR BIOLOGY 2022; 31:60-72. [PMID: 34528734 DOI: 10.1111/imb.12738] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 08/30/2021] [Accepted: 09/13/2021] [Indexed: 06/13/2023]
Abstract
The vacuolar-type H+ -ATPase (V-ATPase) is an ATP-dependent proton pump, which regulates various cellular processes. To date, most functional studies on V-ATPases of insects have focused on subunits of the V1 complex, and there is little information on the VO genes. In this study, two cDNA sequences of LmV-ATPase a were identified in Locusta migratoria. RT-qPCR analysis revealed that LmV-ATPase a1 and LmV-ATPase a2 are differentially expressed in various tissues and developmental stages. Injection of dsRNA for the common region of LmV-ATPase a1 and LmV-ATPase a2 into third-instar nymphs resulted in a significant suppression of LmV-ATPase a. The injected nymphs ceased feeding, lost body weight and finally died at a mortality of 98.6%. Furthermore, aberrations of midgut epithelial cells, the accumulation of electron-lucent vesicles in the cytoplasm, and a partially damaged brush border were observed in dsLmV-ATPase a-injected nymphs using transmission electron microscopy. Especially, the mRNA level of wingles, and notch genes were dramatically down-regulated in the dsLmV-ATPase a-injected nymphs. Taken together, our results suggest that LmV-ATPase a is required for survival and midgut development of L. migratoria. Hence, this gene could be a good target for RNAi-based control against locusts.
Collapse
Affiliation(s)
- X-J Liu
- Research Institute of Applied Biology, Shanxi University, Taiyuan, Shanxi, China
| | - X-Y Liang
- Research Institute of Applied Biology, Shanxi University, Taiyuan, Shanxi, China
| | - J Guo
- Research Institute of Applied Biology, Shanxi University, Taiyuan, Shanxi, China
| | - X-K Shi
- Research Institute of Applied Biology, Shanxi University, Taiyuan, Shanxi, China
| | - H Merzendorfer
- Institute of Biology, University of Siegen, Siegen, Germany
| | - K Y Zhu
- Department of Entomology, Kansas State University, Manhattan, KS, USA
| | - J-Z Zhang
- Research Institute of Applied Biology, Shanxi University, Taiyuan, Shanxi, China
| |
Collapse
|
25
|
Ion Channels and Pumps in Autophagy: A Reciprocal Relationship. Cells 2021; 10:cells10123537. [PMID: 34944044 PMCID: PMC8700256 DOI: 10.3390/cells10123537] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/07/2021] [Accepted: 12/08/2021] [Indexed: 12/24/2022] Open
Abstract
Autophagy, the process of cellular self-degradation, is intrinsically tied to the degradative function of the lysosome. Several diseases have been linked to lysosomal degradative defects, including rare lysosomal storage disorders and neurodegenerative diseases. Ion channels and pumps play a major regulatory role in autophagy. Importantly, calcium signaling produced by TRPML1 (transient receptor potential cation channel, mucolipin subfamily) has been shown to regulate autophagic progression through biogenesis of autophagic-lysosomal organelles, activation of mTORC1 (mechanistic target of rapamycin complex 1) and degradation of autophagic cargo. ER calcium channels such as IP3Rs supply calcium for the lysosome, and lysosomal function is severely disrupted in the absence of lysosomal calcium replenishment by the ER. TRPML1 function is also regulated by LC3 (microtubule-associated protein light chain 3) and mTORC1, two critical components of the autophagic network. Here we provide an overview of the current knowledge about ion channels and pumps-including lysosomal V-ATPase (vacuolar proton-ATPase), which is required for acidification and hence proper enzymatic activity of lysosomal hydrolases-in the regulation of autophagy, and discuss how functional impairment of some of these leads to diseases.
Collapse
|
26
|
|
27
|
Hoffmann N, Peters J. Functions of the (pro)renin receptor (Atp6ap2) at molecular and system levels: pathological implications in hypertension, renal and brain development, inflammation, and fibrosis. Pharmacol Res 2021; 173:105922. [PMID: 34607004 DOI: 10.1016/j.phrs.2021.105922] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/16/2021] [Accepted: 09/29/2021] [Indexed: 12/13/2022]
Abstract
The (pro)renin receptor [(P)RR, Atp6ap2] was initially discovered as a membrane-bound binding partner of prorenin and renin. A soluble (P)RR has additional paracrine effects and is involved in metabolic syndrome and kidney damage. Meanwhile it is clear that most of the effects of the (P)RR are independent of prorenin. In the kidney, (P)RR plays an important role in renal dysfunction by activating proinflammatory and profibrotic molecules. In the brain, (P)RR is expressed in cardiovascular regulatory nuclei and is linked to hypertension. (P)RR is known to be an essential component of the v-ATPase as a key accessory protein and plays an important role in kidney, brain and heart via regulating the pH of the extracellular space and intracellular compartments. V-ATPase and (P)RR together act on WNT and mTOR signalling pathways, which are responsible for cellular homeostasis and autophagy. (P)RR through its role in v-ATPase assembly and function is also important for fast recycling endocytosis by megalin. In the kidney, megalin together with v-ATPase and (P)RR is crucial for endocytic uptake of components of the RAS and their intracellular processing. In the brain, (P)RR, v-ATPases and megalin are important regulators both during development and in the adult. All three proteins are associated with diseases such as XLMR, XMRE, X-linked parkinsonism and epilepsy, cognitive disorders with Parkinsonism, spasticity, intellectual disability, and Alzheimer's Disease which are characterized by impaired neuronal function and/or neuronal loss. The present review focusses on the relevant effects of Atp6ap2 without assigning them necessarily to the RAS. Mechanistically, many effects can be well explained by the role of Atp6ap2 for v-ATPase assembly and function. Furthermore, application of a soluble (P)RR analogue as new therapeutic option is discussed.
Collapse
Affiliation(s)
- Nadin Hoffmann
- Institute of Physiology, University Medicine Greifswald, Friedrich-Ludwig-Jahn-Str. 15A, 17475, Greifswald, Germany
| | - Jörg Peters
- Institute of Physiology, University Medicine Greifswald, Friedrich-Ludwig-Jahn-Str. 15A, 17475, Greifswald, Germany.
| |
Collapse
|
28
|
Hounjet J, Vooijs M. The Role of Intracellular Trafficking of Notch Receptors in Ligand-Independent Notch Activation. Biomolecules 2021; 11:biom11091369. [PMID: 34572582 PMCID: PMC8466058 DOI: 10.3390/biom11091369] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/09/2021] [Accepted: 09/10/2021] [Indexed: 12/11/2022] Open
Abstract
Aberrant Notch signaling has been found in a broad range of human malignancies. Consequently, small molecule inhibitors and antibodies targeting Notch signaling in human cancers have been developed and tested; however, these have failed due to limited anti-tumor efficacy because of dose-limiting toxicities in normal tissues. Therefore, there is an unmet need to discover novel regulators of malignant Notch signaling, which do not affect Notch signaling in healthy tissues. This review provides a comprehensive overview of the current knowledge on the role of intracellular trafficking in ligand-independent Notch receptor activation, the possible mechanisms involved, and possible therapeutic opportunities for inhibitors of intracellular trafficking in Notch targeting.
Collapse
|
29
|
Santra P, Amack JD. Loss of vacuolar-type H+-ATPase induces caspase-independent necrosis-like death of hair cells in zebrafish neuromasts. Dis Model Mech 2021; 14:dmm048997. [PMID: 34296747 PMCID: PMC8319552 DOI: 10.1242/dmm.048997] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 06/15/2021] [Indexed: 01/24/2023] Open
Abstract
The vacuolar-type H+-ATPase (V-ATPase) is a multi-subunit proton pump that regulates cellular pH. V-ATPase activity modulates several cellular processes, but cell-type-specific functions remain poorly understood. Patients with mutations in specific V-ATPase subunits can develop sensorineural deafness, but the underlying mechanisms are unclear. Here, we show that V-ATPase mutations disrupt the formation of zebrafish neuromasts, which serve as a model to investigate hearing loss. V-ATPase mutant neuromasts are small and contain pyknotic nuclei that denote dying cells. Molecular markers and live imaging show that loss of V-ATPase induces mechanosensory hair cells in neuromasts, but not neighboring support cells, to undergo caspase-independent necrosis-like cell death. This is the first demonstration that loss of V-ATPase can lead to necrosis-like cell death in a specific cell type in vivo. Mechanistically, loss of V-ATPase reduces mitochondrial membrane potential in hair cells. Modulating the mitochondrial permeability transition pore, which regulates mitochondrial membrane potential, improves hair cell survival. These results have implications for understanding the causes of sensorineural deafness, and more broadly, reveal functions for V-ATPase in promoting survival of a specific cell type in vivo.
Collapse
Affiliation(s)
- Peu Santra
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
| | - Jeffrey D. Amack
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
- BioInspired Syracuse: Institute for Material and Living Systems, Syracuse, NY 13244, USA
| |
Collapse
|
30
|
Jaskolka MC, Winkley SR, Kane PM. RAVE and Rabconnectin-3 Complexes as Signal Dependent Regulators of Organelle Acidification. Front Cell Dev Biol 2021; 9:698190. [PMID: 34249946 PMCID: PMC8264551 DOI: 10.3389/fcell.2021.698190] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 05/28/2021] [Indexed: 12/12/2022] Open
Abstract
The yeast RAVE (Regulator of H+-ATPase of Vacuolar and Endosomal membranes) complex and Rabconnectin-3 complexes of higher eukaryotes regulate acidification of organelles such as lysosomes and endosomes by catalyzing V-ATPase assembly. V-ATPases are highly conserved proton pumps consisting of a peripheral V1 subcomplex that contains the sites of ATP hydrolysis, attached to an integral membrane Vo subcomplex that forms the transmembrane proton pore. Reversible disassembly of the V-ATPase is a conserved regulatory mechanism that occurs in response to multiple signals, serving to tune ATPase activity and compartment acidification to changing extracellular conditions. Signals such as glucose deprivation can induce release of V1 from Vo, which inhibits both ATPase activity and proton transport. Reassembly of V1 with Vo restores ATP-driven proton transport, but requires assistance of the RAVE or Rabconnectin-3 complexes. Glucose deprivation triggers V-ATPase disassembly in yeast and is accompanied by binding of RAVE to V1 subcomplexes. Upon glucose readdition, RAVE catalyzes both recruitment of V1 to the vacuolar membrane and its reassembly with Vo. The RAVE complex can be recruited to the vacuolar membrane by glucose in the absence of V1 subunits, indicating that the interaction between RAVE and the Vo membrane domain is glucose-sensitive. Yeast RAVE complexes also distinguish between organelle-specific isoforms of the Vo a-subunit and thus regulate distinct V-ATPase subpopulations. Rabconnectin-3 complexes in higher eukaryotes appear to be functionally equivalent to yeast RAVE. Originally isolated as a two-subunit complex from rat brain, the Rabconnectin-3 complex has regions of homology with yeast RAVE and was shown to interact with V-ATPase subunits and promote endosomal acidification. Current understanding of the structure and function of RAVE and Rabconnectin-3 complexes, their interactions with the V-ATPase, their role in signal-dependent modulation of organelle acidification, and their impact on downstream pathways will be discussed.
Collapse
Affiliation(s)
- Michael C Jaskolka
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Samuel R Winkley
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, United States
| |
Collapse
|
31
|
Kidney intercalated cells and the transcription factor FOXi1 drive cystogenesis in tuberous sclerosis complex. Proc Natl Acad Sci U S A 2021; 118:2020190118. [PMID: 33536341 PMCID: PMC8017711 DOI: 10.1073/pnas.2020190118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is caused by mutations in TSC1 or TSC2 gene and affects multiple organs, including the kidney, where it presents with angiomyolipomata and cysts that can result in kidney failure. The factors promoting cyst formation and tumor growth in TSC are incompletely understood. Current studies demonstrate that kidney cyst epithelia in TSC mouse models and in humans with TSC are composed of hyperproliferating intercalated cells, along with activation of H+-ATPase and carbonic anhydrase 2. Interfering with intercalated cell proliferation completely inhibited and inactivating carbonic anhydrase 2 significantly protected against cyst formation in TSC. Targeting the acid base and/or electrolyte transporters of intercalated cells may provide a therapeutic approach for the treatment of kidney cysts in TSC. Tuberous sclerosis complex (TSC) is caused by mutations in either TSC1 or TSC2 genes and affects multiple organs, including kidney, lung, and brain. In the kidney, TSC presents with the enlargement of benign tumors (angiomyolipomata) and cysts, which eventually leads to kidney failure. The factors promoting cyst formation and tumor growth in TSC are incompletely understood. Here, we report that mice with principal cell-specific inactivation of Tsc1 develop numerous cortical cysts, which are overwhelmingly composed of hyperproliferating A-intercalated (A-IC) cells. RNA sequencing and confirmatory expression studies demonstrated robust expression of Forkhead Transcription Factor 1 (Foxi1) and its downstream targets, apical H+-ATPase and cytoplasmic carbonic anhydrase 2 (CAII), in cyst epithelia in Tsc1 knockout (KO) mice but not in Pkd1 mutant mice. In addition, the electrogenic 2Cl−/H+ exchanger (CLC-5) is significantly up-regulated and shows remarkable colocalization with H+-ATPase on the apical membrane of cyst epithelia in Tsc1 KO mice. Deletion of Foxi1, which is vital to intercalated cells viability and H+-ATPase expression, completely abrogated the cyst burden in Tsc1 KO mice, as indicated by MRI images and histological analysis in kidneys of Foxi1/Tsc1 double-knockout (dKO) mice. Deletion of CAII, which is critical to H+-ATPase activation, caused significant reduction in cyst burden and increased life expectancy in CAII/Tsc1 dKO mice vs. Tsc1 KO mice. We propose that intercalated cells and their acid/base/electrolyte transport machinery (H+-ATPase/CAII/CLC-5) are critical to cystogenesis, and their inhibition or inactivation is associated with significant protection against cyst generation and/or enlargement in TSC.
Collapse
|
32
|
Schneider L, Guo Y, Birch D, Sarkies P. Network-based visualisation reveals new insights into transposable element diversity. Mol Syst Biol 2021; 17:e9600. [PMID: 34169647 PMCID: PMC8226279 DOI: 10.15252/msb.20209600] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 05/23/2021] [Accepted: 05/27/2021] [Indexed: 01/12/2023] Open
Abstract
Transposable elements (TEs) are widespread across eukaryotic genomes, yet their content varies widely between different species. Factors shaping the diversity of TEs are poorly understood. Understanding the evolution of TEs is difficult because their sequences diversify rapidly and TEs are often transferred through non-conventional means such as horizontal gene transfer. We developed a method to track TE evolution using network analysis to visualise TE sequence and TE content across different genomes. We illustrate our method by first using a monopartite network to study the sequence evolution of Tc1/mariner elements across focal species. We identify a connection between two subfamilies associated with convergent acquisition of a domain from a protein-coding gene. Second, we use a bipartite network to study how TE content across species is shaped by epigenetic silencing mechanisms. We show that the presence of Piwi-interacting RNAs is associated with differences in network topology after controlling for phylogenetic effects. Together, our method demonstrates how a network-based approach can identify hitherto unknown properties of TE evolution across species.
Collapse
Affiliation(s)
- Lisa Schneider
- MRC London Institute of Medical SciencesLondonUK
- Institute of Clinical SciencesImperial CollegeLondonUK
- Data Sciences InstituteImperial CollegeLondonUK
| | - Yi‐Ke Guo
- Data Sciences InstituteImperial CollegeLondonUK
- Present address:
Hong Kong Baptist UniversityKowloon TsaiHong Kong
| | - David Birch
- Data Sciences InstituteImperial CollegeLondonUK
| | - Peter Sarkies
- MRC London Institute of Medical SciencesLondonUK
- Institute of Clinical SciencesImperial CollegeLondonUK
| |
Collapse
|
33
|
Intracellular trafficking of Notch orchestrates temporal dynamics of Notch activity in the fly brain. Nat Commun 2021; 12:2083. [PMID: 33828096 PMCID: PMC8027629 DOI: 10.1038/s41467-021-22442-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 03/16/2021] [Indexed: 12/03/2022] Open
Abstract
While Delta non-autonomously activates Notch in neighboring cells, it autonomously inactivates Notch through cis-inhibition, the molecular mechanism and biological roles of which remain elusive. The wave of differentiation in the Drosophila brain, the ‘proneural wave’, is an excellent model for studying Notch signaling in vivo. Here, we show that strong nonlinearity in cis-inhibition reproduces the second peak of Notch activity behind the proneural wave in silico. Based on this, we demonstrate that Delta expression induces a quick degradation of Notch in late endosomes and the formation of the twin peaks of Notch activity in vivo. Indeed, the amount of Notch is upregulated and the twin peaks are fused forming a single peak when the function of Delta or late endosomes is compromised. Additionally, we show that the second Notch peak behind the wavefront controls neurogenesis. Thus, intracellular trafficking of Notch orchestrates the temporal dynamics of Notch activity and the temporal patterning of neurogenesis. During Drosophila development, two peaks of Notch activity propagate across the neuroepithelium to generate neuroblasts. Here, the authors show Notch cis-inhibition under the control of intracellular Notch trafficking establishes these two peaks, which temporally control neurogenesis in the brain.
Collapse
|
34
|
Inhibiting ATP6V0D2 Aggravates Liver Ischemia-Reperfusion Injury by Promoting NLRP3 Activation via Impairing Autophagic Flux Independent of Notch1/Hes1. J Immunol Res 2021; 2021:6670495. [PMID: 33860063 PMCID: PMC8024071 DOI: 10.1155/2021/6670495] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 02/10/2021] [Accepted: 03/10/2021] [Indexed: 02/06/2023] Open
Abstract
At present, liver ischemia-reperfusion (IR) injury is still a great challenge for clinical liver partial resection and liver transplantation. The innate immunity regulated by liver macrophages orchestrates the cascade of IR inflammation and acts as a bridge. As a specific macrophage subunit of vacuolar ATPase, ATP6V0D2 (V-ATPase D2 subunit) has been shown to promote the formation of autophagolysosome in vitro. Our research fills a gap which has existed in the study of inflammatory stress about the V-ATPase subunit ATP6V0D2 in liver macrophages. We first found that the expression of specific ATP6V0D2 in liver macrophages was upregulated with the induction of inflammatory cascade after liver IR surgery, and knockdown of ATP6V0D2 resulted in increased secretion of proinflammatory factors and chemokines, which enhanced activation of NLRP3 and aggravation of liver injury. Further studies found that the exacerbated activation of NLRP3 was related to the autophagic flux regulated by ATP6V0D2. Knocking down ATP6V0D2 impaired the formation of autophagolysosome and aggravated liver IR injury through nonspecific V-ATPase activation independent of V-ATPase-Notchl-Hesl signal axis. In general, we illustrated that the expression of ATP6V0D2 in liver macrophages was upregulated after liver IR, and by gradually promoting the formation of autophagolysosomes to increase autophagy flux to limit the activation of liver inflammation, this regulation is independent of the Notch1-Hes1 signal axis.
Collapse
|
35
|
Class II phosphatidylinositol 3-kinase-C2α is essential for Notch signaling by regulating the endocytosis of γ-secretase in endothelial cells. Sci Rep 2021; 11:5199. [PMID: 33664344 PMCID: PMC7933152 DOI: 10.1038/s41598-021-84548-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 02/16/2021] [Indexed: 01/09/2023] Open
Abstract
The class II α-isoform of phosphatidylinositol 3-kinase (PI3K-C2α) plays a crucial role in angiogenesis at least in part through participating in endocytosis and, thereby, endosomal signaling of several cell surface receptors including VEGF receptor-2 and TGFβ receptor in vascular endothelial cells (ECs). The Notch signaling cascade regulates many cellular processes including cell proliferation, cell fate specification and differentiation. In the present study, we explored a role of PI3K-C2α in Delta-like 4 (Dll4)-induced Notch signaling in ECs. We found that knockdown of PI3K-C2α inhibited Dll4-induced generation of the signaling molecule Notch intracellular domain 1 (NICD1) and the expression of Notch1 target genes including HEY1, HEY2 and NOTCH3 in ECs but not in vascular smooth muscle cells. PI3K-C2α knockdown did not inhibit Dll4-induced endocytosis of cell surface Notch1. In contrast, PI3K-C2α knockdown as well as clathrin heavy chain knockdown impaired endocytosis of Notch1-cleaving protease, γ-secretase complex, with the accumulation of Notch1 at the perinuclear endolysosomes. Pharmacological blockage of γ-secretase also induced the intracellular accumulation of Notch1. Taken together, we conclude that PI3K-C2α is required for the clathrin-mediated endocytosis of γ-secretase complex, which allows for the cleavage of endocytosed Notch1 by γ-secretase complex at the endolysosomes to generate NICD1 in ECs.
Collapse
|
36
|
Amiri M, Seidler UE, Nikolovska K. The Role of pH i in Intestinal Epithelial Proliferation-Transport Mechanisms, Regulatory Pathways, and Consequences. Front Cell Dev Biol 2021; 9:618135. [PMID: 33553180 PMCID: PMC7862550 DOI: 10.3389/fcell.2021.618135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 01/04/2021] [Indexed: 01/07/2023] Open
Abstract
During the maturation of intestinal epithelial cells along the crypt/surface axis, a multitude of acid/base transporters are differentially expressed in their apical and basolateral membranes, enabling processes of electrolyte, macromolecule, nutrient, acid/base and fluid secretion, and absorption. An intracellular pH (pHi)-gradient is generated along the epithelial crypt/surface axis, either as a consequence of the sum of the ion transport activities or as a distinctly regulated entity. While the role of pHi on proliferation, migration, and tumorigenesis has been explored in cancer cells for some time, emerging evidence suggests an important role of the pHi in the intestinal stem cells (ISCs) proliferative rate under physiological conditions. The present review highlights the current state of knowledge about the potential regulatory role of pHi on intestinal proliferation and differentiation.
Collapse
|
37
|
Pannen H, Rapp T, Klein T. The ESCRT machinery regulates retromer-dependent transcytosis of septate junction components in Drosophila. eLife 2020; 9:61866. [PMID: 33377869 PMCID: PMC7848756 DOI: 10.7554/elife.61866] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/29/2020] [Indexed: 12/30/2022] Open
Abstract
Loss of ESCRT function in Drosophila imaginal discs is known to cause neoplastic overgrowth fueled by mis-regulation of signaling pathways. Its impact on junctional integrity, however, remains obscure. To dissect the events leading to neoplasia, we used transmission electron microscopy (TEM) on wing imaginal discs temporally depleted of the ESCRT-III core component Shrub. We find a specific requirement for Shrub in maintaining septate junction (SJ) integrity by transporting the claudin Megatrachea (Mega) to the SJ. In absence of Shrub function, Mega is lost from the SJ and becomes trapped on endosomes coated with the endosomal retrieval machinery retromer. We show that ESCRT function is required for apical localization and mobility of retromer positive carrier vesicles, which mediate the biosynthetic delivery of Mega to the SJ. Accordingly, loss of retromer function impairs the anterograde transport of several SJ core components, revealing a novel physiological role for this ancient endosomal agent. Proteins are large molecules responsible for a variety of activities that cells needs to perform to survive; from respiration to copying DNA before cells divide. To perform these roles proteins need to be transported to the correct cell compartment, or to the cell membrane. This protein trafficking depends on the endosomal system, a set of membrane compartments that can travel within the cell and act as a protein sorting hub. This system needs its own proteins to work properly. In particular, there are two sets of proteins that are crucial for the endosomal systems activity: a group of proteins known as the ESCRT (endosomal sorting complex required for transport) machinery and a complex called retromer. The retromer complex regulates recycling of receptor proteins so they can be reused, while the ESCRT machinery mediates degradation of proteins that the cell does not require anymore. In the epithelia of fruit fly larvae – the tissues that form layers of cells, usually covering an organ but also making structures like wings – defects in ESCRT activity lead to a loss of tissue integrity. This loss of tissue integrity suggests that the endosomal system might be involved in transporting proteins that form cellular junctions, the multiprotein complexes that establish contacts between cells or between a cell and the extracellular space. In arthropods such as the fruit fly, the adherens junction and the septate junction are two types of cellular junctions important for the integrity of epithelia integrity. Adherens junctions allow cells to adhere to each other, while septate junctions stop nutrient molecules, ions and water from leaking into the tissue. The role of the endosomal system in trafficking the proteins that form septate junctions remains a mystery. To better understand the role of the endosomal system in regulating cell junctions and tissue integrity, Pannen et al. blocked the activity of either the ESCRT or retromer in wing imaginal discs – the future wings – of fruit fly larvae. Pannen et al. then analyzed the effects of these endosomal defects on cellular junctions using an imaging technique called transmission electron microscopy. The results showed that both ESCRT and retromer activities are necessary for the correct delivery of septate junction components to the cell membrane. However, neither retromer nor ESCRT were required for the delivery of adherens junction proteins. These findings shed light on how retromer and the ESCRT machinery are involved in the epithelial tissue integrity of fruit fly larvae through their effects on cell junctions. Humans have their own versions of the ESCRT, retromer, and cell junction proteins, all of which are very similar to their fly counterparts. Since defects in the human versions of these proteins have been associated with a variety of diseases, from infections to cancer, these results may have implications for research into treating those diseases.
Collapse
Affiliation(s)
- Hendrik Pannen
- Institute of Genetics, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Tim Rapp
- Institute of Genetics, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Thomas Klein
- Institute of Genetics, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| |
Collapse
|
38
|
Eaton AF, Merkulova M, Brown D. The H +-ATPase (V-ATPase): from proton pump to signaling complex in health and disease. Am J Physiol Cell Physiol 2020; 320:C392-C414. [PMID: 33326313 PMCID: PMC8294626 DOI: 10.1152/ajpcell.00442.2020] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A primary function of the H+-ATPase (or V-ATPase) is to create an electrochemical proton gradient across eukaryotic cell membranes, which energizes fundamental cellular processes. Its activity allows for the acidification of intracellular vesicles and organelles, which is necessary for many essential cell biological events to occur. In addition, many specialized cell types in various organ systems such as the kidney, bone, male reproductive tract, inner ear, olfactory mucosa, and more, use plasma membrane V-ATPases to perform specific activities that depend on extracellular acidification. It is, however, increasingly apparent that V-ATPases are central players in many normal and pathophysiological processes that directly influence human health in many different and sometimes unexpected ways. These include cancer, neurodegenerative diseases, diabetes, and sensory perception, as well as energy and nutrient-sensing functions within cells. This review first covers the well-established role of the V-ATPase as a transmembrane proton pump in the plasma membrane and intracellular vesicles and outlines factors contributing to its physiological regulation in different cell types. This is followed by a discussion of the more recently emerging unconventional roles for the V-ATPase, such as its role as a protein interaction hub involved in cell signaling, and the (patho)physiological implications of these interactions. Finally, the central importance of endosomal acidification and V-ATPase activity on viral infection will be discussed in the context of the current COVID-19 pandemic.
Collapse
Affiliation(s)
- Amity F Eaton
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Maria Merkulova
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Dennis Brown
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| |
Collapse
|
39
|
York HM, Coyle J, Arumugam S. To be more precise: the role of intracellular trafficking in development and pattern formation. Biochem Soc Trans 2020; 48:2051-2066. [PMID: 32915197 PMCID: PMC7609031 DOI: 10.1042/bst20200223] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 08/24/2020] [Accepted: 08/26/2020] [Indexed: 02/07/2023]
Abstract
Living cells interpret a variety of signals in different contexts to elucidate functional responses. While the understanding of signalling molecules, their respective receptors and response at the gene transcription level have been relatively well-explored, how exactly does a single cell interpret a plethora of time-varying signals? Furthermore, how their subsequent responses at the single cell level manifest in the larger context of a developing tissue is unknown. At the same time, the biophysics and chemistry of how receptors are trafficked through the complex dynamic transport network between the plasma membrane-endosome-lysosome-Golgi-endoplasmic reticulum are much more well-studied. How the intracellular organisation of the cell and inter-organellar contacts aid in orchestrating trafficking, as well as signal interpretation and modulation by the cells are beginning to be uncovered. In this review, we highlight the significant developments that have strived to integrate endosomal trafficking, signal interpretation in the context of developmental biology and relevant open questions with a few chosen examples. Furthermore, we will discuss the imaging technologies that have been developed in the recent past that have the potential to tremendously accelerate knowledge gain in this direction while shedding light on some of the many challenges.
Collapse
Affiliation(s)
- Harrison M. York
- Monash Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC 3800, Australia
| | - Joanne Coyle
- Monash Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC 3800, Australia
| | - Senthil Arumugam
- Monash Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC 3800, Australia
- European Molecular Biological Laboratory Australia (EMBL Australia), Monash University, Melbourne, VIC 3800, Australia
- ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, VIC 3800, Australia
| |
Collapse
|
40
|
Pagliaro L, Sorrentino C, Roti G. Targeting Notch Trafficking and Processing in Cancers. Cells 2020; 9:E2212. [PMID: 33003595 PMCID: PMC7600097 DOI: 10.3390/cells9102212] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/02/2020] [Accepted: 09/08/2020] [Indexed: 02/06/2023] Open
Abstract
The Notch family comprises a group of four ligand-dependent receptors that control evolutionarily conserved developmental and homeostatic processes and transmit signals to the microenvironment. NOTCH undergoes remodeling, maturation, and trafficking in a series of post-translational events, including glycosylation, ubiquitination, and endocytosis. The regulatory modifications occurring in the endoplasmic reticulum/Golgi precede the intramembrane γ-secretase proteolysis and the transfer of active NOTCH to the nucleus. Hence, NOTCH proteins coexist in different subcellular compartments and undergo continuous relocation. Various factors, including ion concentration, enzymatic activity, and co-regulatory elements control Notch trafficking. Interfering with these regulatory mechanisms represents an innovative therapeutic way to bar oncogenic Notch signaling. In this review, we briefly summarize the role of Notch signaling in cancer and describe the protein modifications required for NOTCH to relocate across different subcellular compartments. We focus on the functional relationship between these modifications and the corresponding therapeutic options, and our findings could support the development of trafficking modulators as a potential alternative to the well-known γ-secretase inhibitors.
Collapse
Affiliation(s)
| | | | - Giovanni Roti
- Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy; (L.P.); (C.S.)
| |
Collapse
|
41
|
Takai A, Yamaguchi M, Yoshida H, Chiyonobu T. Investigating Developmental and Epileptic Encephalopathy Using Drosophila melanogaster. Int J Mol Sci 2020; 21:ijms21176442. [PMID: 32899411 PMCID: PMC7503973 DOI: 10.3390/ijms21176442] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 08/30/2020] [Accepted: 09/01/2020] [Indexed: 12/16/2022] Open
Abstract
Developmental and epileptic encephalopathies (DEEs) are the spectrum of severe epilepsies characterized by early-onset, refractory seizures occurring in the context of developmental regression or plateauing. Early infantile epileptic encephalopathy (EIEE) is one of the earliest forms of DEE, manifesting as frequent epileptic spasms and characteristic electroencephalogram findings in early infancy. In recent years, next-generation sequencing approaches have identified a number of monogenic determinants underlying DEE. In the case of EIEE, 85 genes have been registered in Online Mendelian Inheritance in Man as causative genes. Model organisms are indispensable tools for understanding the in vivo roles of the newly identified causative genes. In this review, we first present an overview of epilepsy and its genetic etiology, especially focusing on EIEE and then briefly summarize epilepsy research using animal and patient-derived induced pluripotent stem cell (iPSC) models. The Drosophila model, which is characterized by easy gene manipulation, a short generation time, low cost and fewer ethical restrictions when designing experiments, is optimal for understanding the genetics of DEE. We therefore highlight studies with Drosophila models for EIEE and discuss the future development of their practical use.
Collapse
Affiliation(s)
- Akari Takai
- Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan;
| | - Masamitsu Yamaguchi
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 603-8585, Japan; (M.Y.); (H.Y.)
- Kansai Gakken Laboratory, Kankyo Eisei Yakuhin Co. Ltd., Kyoto 619-0237, Japan
| | - Hideki Yoshida
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 603-8585, Japan; (M.Y.); (H.Y.)
| | - Tomohiro Chiyonobu
- Department of Pediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan;
- Correspondence:
| |
Collapse
|
42
|
Mo D, Chen Y, Jiang N, Shen J, Zhang J. Investigation of Isoform Specific Functions of the V-ATPase a Subunit During Drosophila Wing Development. Front Genet 2020; 11:723. [PMID: 32754202 PMCID: PMC7365883 DOI: 10.3389/fgene.2020.00723] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 06/15/2020] [Indexed: 12/12/2022] Open
Abstract
The vacuolar ATPases (V-ATPases) are ATP-dependent proton pumps that play vital roles in eukaryotic cells. Insect V-ATPases are required in nearly all epithelial tissues to regulate a multiplicity of processes including receptor-mediated endocytosis, protein degradation, fluid secretion, and neurotransmission. Composed of fourteen different subunits, several V-ATPase subunits exist in distinct isoforms to perform cell type specific functions. The 100 kD a subunit (Vha100) of V-ATPases are encoded by a family of five genes in Drosophila, but their assignments are not fully understood. Here we report an experimental survey of the Vha100 gene family during Drosophila wing development. A combination of CRISPR-Cas9 mutagenesis, somatic clonal analysis and in vivo RNAi assays is used to characterize the requirement of Vha100 isoforms, and mutants of Vha100-2, Vha100-3, Vha100-4, and Vha100-5 genes were generated. We show that Vha100-3 and Vha100-5 are dispensable for fly development, while Vha100-1 is not critically required in the wing. As for the other two isoforms, we find that Vha100-2 regulates wing cuticle maturation, while Vha100-4 is the single isoform involved in developmental patterning. More specifically, Vha100-4 is required for proper activation of the Wingless signaling pathway during fly wing development. Interestingly, we also find a specific genetic interaction between Vha100-1 and Vha100-4 during wing development. Our results revealed the distinct roles of Vha100 isoforms during insect wing development, providing a rationale for understanding the diverse roles of V-ATPases.
Collapse
Affiliation(s)
- Dongqing Mo
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Yao Chen
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Na Jiang
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Jie Shen
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Junzheng Zhang
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| |
Collapse
|
43
|
Collins MP, Forgac M. Regulation and function of V-ATPases in physiology and disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183341. [PMID: 32422136 DOI: 10.1016/j.bbamem.2020.183341] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/30/2020] [Accepted: 05/03/2020] [Indexed: 02/07/2023]
Abstract
The vacuolar H+-ATPases (V-ATPases) are essential, ATP-dependent proton pumps present in a variety of eukaryotic cellular membranes. Intracellularly, V-ATPase-dependent acidification functions in such processes as membrane traffic, protein degradation, autophagy and the coupled transport of small molecules. V-ATPases at the plasma membrane of certain specialized cells function in such processes as bone resorption, sperm maturation and urinary acidification. V-ATPases also function in disease processes such as pathogen entry and cancer cell invasiveness, while defects in V-ATPase genes are associated with disorders such as osteopetrosis, renal tubular acidosis and neurodegenerative diseases. This review highlights recent advances in our understanding of V-ATPase structure, mechanism, function and regulation, with an emphasis on the signaling pathways controlling V-ATPase assembly in mammalian cells. The role of V-ATPases in cancer and other human pathologies, and the prospects for therapeutic intervention, are also discussed.
Collapse
Affiliation(s)
- Michael P Collins
- Cell, Molecular and Developmental Biology, Tufts University Graduate School of Biomedical Sciences, United States of America
| | - Michael Forgac
- Cell, Molecular and Developmental Biology, Tufts University Graduate School of Biomedical Sciences, United States of America; Dept. of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, United States of America.
| |
Collapse
|
44
|
Song Q, Meng B, Xu H, Mao Z. The emerging roles of vacuolar-type ATPase-dependent Lysosomal acidification in neurodegenerative diseases. Transl Neurodegener 2020; 9:17. [PMID: 32393395 PMCID: PMC7212675 DOI: 10.1186/s40035-020-00196-0] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 04/23/2020] [Indexed: 12/15/2022] Open
Abstract
Background Lysosomes digest extracellular material from the endocytic pathway and intracellular material from the autophagic pathway. This process is performed by the resident hydrolytic enzymes activated by the highly acidic pH within the lysosomal lumen. Lysosome pH gradients are mainly maintained by the vacuolar (H+) ATPase (or V-ATPase), which pumps protons into lysosomal lumen by consuming ATP. Dysfunction of V-ATPase affects lysosomal acidification, which disrupts the clearance of substrates and leads to many disorders, including neurodegenerative diseases. Main body As a large multi-subunit complex, the V-ATPase is composed of an integral membrane V0 domain involved in proton translocation and a peripheral V1 domain catalyzing ATP hydrolysis. The canonical functions of V-ATPase rely on its H+-pumping ability in multiple vesicle organelles to regulate endocytic traffic, protein processing and degradation, synaptic vesicle loading, and coupled transport. The other non-canonical effects of the V-ATPase that are not readily attributable to its proton-pumping activity include membrane fusion, pH sensing, amino-acid-induced activation of mTORC1, and scaffolding for protein-protein interaction. In response to various stimuli, V-ATPase complex can reversibly dissociate into V1 and V0 domains and thus close ATP-dependent proton transport. Dysregulation of pH and lysosomal dysfunction have been linked to many human diseases, including neurodegenerative disorders such as Alzheimer disease, Parkinson’s disease, amyotrophic lateral sclerosis as well as neurodegenerative lysosomal storage disorders. Conclusion V-ATPase complex is a universal proton pump and plays an important role in lysosome acidification in all types of cells. Since V-ATPase dysfunction contributes to the pathogenesis of multiple neurodegenerative diseases, further understanding the mechanisms that regulate the canonical and non-canonical functions of V-ATPase will reveal molecular details of disease process and help assess V-ATPase or molecules related to its regulation as therapeutic targets.
Collapse
Affiliation(s)
- Qiaoyun Song
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Department of Reproductive Genetics, Hebei General Hospital, Shijiazhuang, Hebei Province, 050051, People's Republic of China.,Department of Neurology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Bo Meng
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Department of Neurology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Haidong Xu
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Department of Neurology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Zixu Mao
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA. .,Department of Neurology, Emory University School of Medicine, Atlanta, GA, 30322, USA.
| |
Collapse
|
45
|
Laiouar S, Berns N, Brech A, Riechmann V. RabX1 Organizes a Late Endosomal Compartment that Forms Tubular Connections to Lysosomes Consistent with a “Kiss and Run” Mechanism. Curr Biol 2020; 30:1177-1188.e5. [DOI: 10.1016/j.cub.2020.01.048] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 12/17/2019] [Accepted: 01/14/2020] [Indexed: 01/26/2023]
|
46
|
Fassio A, Falace A, Esposito A, Aprile D, Guerrini R, Benfenati F. Emerging Role of the Autophagy/Lysosomal Degradative Pathway in Neurodevelopmental Disorders With Epilepsy. Front Cell Neurosci 2020; 14:39. [PMID: 32231521 PMCID: PMC7082311 DOI: 10.3389/fncel.2020.00039] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 02/10/2020] [Indexed: 01/08/2023] Open
Abstract
Autophagy is a highly conserved degradative process that conveys dysfunctional proteins, lipids, and organelles to lysosomes for degradation. The post-mitotic nature, complex and highly polarized morphology, and high degree of specialization of neurons make an efficient autophagy essential for their homeostasis and survival. Dysfunctional autophagy occurs in aging and neurodegenerative diseases, and autophagy at synaptic sites seems to play a crucial role in neurodegeneration. Moreover, a role of autophagy is emerging for neural development, synaptogenesis, and the establishment of a correct connectivity. Thus, it is not surprising that defective autophagy has been demonstrated in a spectrum of neurodevelopmental disorders, often associated with early-onset epilepsy. Here, we discuss the multiple roles of autophagy in neurons and the recent experimental evidence linking neurodevelopmental disorders with epilepsy to genes coding for autophagic/lysosomal system-related proteins and envisage possible pathophysiological mechanisms ranging from synaptic dysfunction to neuronal death.
Collapse
Affiliation(s)
- Anna Fassio
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Antonio Falace
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy
| | - Alessandro Esposito
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Davide Aprile
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy.,IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Fabio Benfenati
- IRCCS Ospedale Policlinico San Martino, Genoa, Italy.,Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
| |
Collapse
|
47
|
Vasanthakumar T, Rubinstein JL. Structure and Roles of V-type ATPases. Trends Biochem Sci 2020; 45:295-307. [PMID: 32001091 DOI: 10.1016/j.tibs.2019.12.007] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/05/2019] [Accepted: 12/31/2019] [Indexed: 12/19/2022]
Abstract
V-ATPases are membrane-embedded protein complexes that function as ATP hydrolysis-driven proton pumps. V-ATPases are the primary source of organellar acidification in all eukaryotes, making them essential for many fundamental cellular processes. Enzymatic activity can be modulated by regulated and reversible disassembly of the complex, and several subunits of mammalian V-ATPase have multiple isoforms that are differentially localized. Although the biochemical properties of the different isoforms are currently unknown, mutations in specific subunit isoforms have been associated with various diseases, making V-ATPases potential drug targets. V-ATPase structure and activity have been best characterized in Saccharomyces cerevisiae, where recent structures have revealed details about the dynamics of the enzyme, the proton translocation pathway, and conformational changes associated with regulated disassembly and autoinhibition.
Collapse
Affiliation(s)
- Thamiya Vasanthakumar
- The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - John L Rubinstein
- The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, The University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Medical Biophysics, The University of Toronto, Toronto, ON M5G 1L7, Canada.
| |
Collapse
|
48
|
Gowrisankaran S, Milosevic I. Regulation of synaptic vesicle acidification at the neuronal synapse. IUBMB Life 2020; 72:568-576. [DOI: 10.1002/iub.2235] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Accepted: 12/29/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Sindhuja Gowrisankaran
- European Neuroscience Institute (ENI)A Joint Initiative of the University Medical Center Göttingen and the Max Planck Society Göttingen Germany
| | - Ira Milosevic
- European Neuroscience Institute (ENI)A Joint Initiative of the University Medical Center Göttingen and the Max Planck Society Göttingen Germany
| |
Collapse
|
49
|
Jaskolka MC, Kane PM. Interaction between the yeast RAVE complex and Vph1-containing V o sectors is a central glucose-sensitive interaction required for V-ATPase reassembly. J Biol Chem 2020; 295:2259-2269. [PMID: 31941791 DOI: 10.1074/jbc.ra119.011522] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/02/2020] [Indexed: 12/12/2022] Open
Abstract
The yeast vacuolar H+-ATPase (V-ATPase) of budding yeast (Saccharomyces cerevisiae) is regulated by reversible disassembly. Disassembly inhibits V-ATPase activity under low-glucose conditions by releasing peripheral V1 subcomplexes from membrane-bound Vo subcomplexes. V-ATPase reassembly and reactivation requires intervention of the conserved regulator of H+-ATPase of vacuoles and endosomes (RAVE) complex, which binds to cytosolic V1 subcomplexes and assists reassembly with integral membrane Vo complexes. Consistent with its role, the RAVE complex itself is reversibly recruited to the vacuolar membrane by glucose, but the requirements for its recruitment are not understood. We demonstrate here that RAVE recruitment to the membrane does not require an interaction with V1 Glucose-dependent RAVE localization to the vacuolar membrane required only intact Vo complexes containing the Vph1 subunit, suggesting that the RAVE-Vo interaction is glucose-dependent. We identified a short conserved sequence in the center of the RAVE subunit Rav1 that is essential for the interaction with Vph1 in vivo and in vitro Mutations in this region resulted in the temperature- and pH-dependent growth phenotype characteristic of ravΔ mutants. However, this region did not account for glucose sensitivity of the Rav1-Vph1 interaction. We quantitated glucose-dependent localization of a GFP-tagged RAVE subunit to the vacuolar membrane in several mutants previously implicated in altering V-ATPase assembly state or glucose-induced assembly. RAVE localization did not correlate with V-ATPase assembly levels reported previously in these mutants, highlighting both the catalytic nature of RAVE's role in V-ATPase assembly and the likelihood of glucose signaling to RAVE independently of V1.
Collapse
Affiliation(s)
- Michael C Jaskolka
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210.
| |
Collapse
|
50
|
Graves HK, Jangam S, Tan KL, Pignata A, Seto ES, Yamamoto S, Wangler MF. A Genetic Screen for Genes That Impact Peroxisomes in Drosophila Identifies Candidate Genes for Human Disease. G3 (BETHESDA, MD.) 2020; 10:69-77. [PMID: 31767637 PMCID: PMC6945042 DOI: 10.1534/g3.119.400803] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 11/11/2019] [Indexed: 02/06/2023]
Abstract
Peroxisomes are subcellular organelles that are essential for proper function of eukaryotic cells. In addition to being the sites of a variety of oxidative reactions, they are crucial regulators of lipid metabolism. Peroxisome loss or dysfunction leads to multi-system diseases in humans that strongly affect the nervous system. In order to identify previously unidentified genes and mechanisms that impact peroxisomes, we conducted a genetic screen on a collection of lethal mutations on the X chromosome in Drosophila Using the number, size and morphology of GFP tagged peroxisomes as a readout, we screened for mutations that altered peroxisomes based on clonal analysis and confocal microscopy. From this screen, we identified eighteen genes that cause increases in peroxisome number or altered morphology when mutated. We examined the human homologs of these genes and found that they are involved in a diverse array of cellular processes. Interestingly, the human homologs from the X-chromosome collection are under selective constraint in human populations and are good candidate genes particularly for dominant genetic disease. This in vivo screening approach for peroxisome defects allows identification of novel genes that impact peroxisomes in vivo in a multicellular organism and is a valuable platform to discover genes potentially involved in dominant disease that could affect peroxisomes.
Collapse
Affiliation(s)
| | | | - Kai Li Tan
- Department of Molecular and Human Genetics
| | | | | | - Shinya Yamamoto
- Department of Molecular and Human Genetics,
- Department of Neuroscience
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, and
- Jan and Dan Duncan Neurological Research Institute, Texas Children Hospital, Houston, TX 77030
| | - Michael F Wangler
- Department of Molecular and Human Genetics,
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, and
- Jan and Dan Duncan Neurological Research Institute, Texas Children Hospital, Houston, TX 77030
| |
Collapse
|