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Bhat M, Nambiar A, Edakkandiyil L, Abraham IM, Sen R, Negi M, Manjithaya R. A genetically-encoded fluorescence-based reporter to spatiotemporally investigate mannose-6-phosphate pathway. Mol Biol Cell 2024; 35:mr6. [PMID: 38888935 DOI: 10.1091/mbc.e23-09-0344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024] Open
Abstract
Maintenance of a pool of active lysosomes with acidic pH and degradative hydrolases is crucial for cell health. Abnormalities in lysosomal function are closely linked to diseases, such as lysosomal storage disorders, neurodegeneration, intracellular infections, and cancer among others. Emerging body of research suggests the malfunction of lysosomal hydrolase trafficking pathway to be a common denominator of several disease pathologies. However, available conventional tools to assess lysosomal hydrolase trafficking are insufficient and fail to provide a comprehensive picture about the trafficking flux and location of lysosomal hydrolases. To address some of the shortcomings, we designed a genetically-encoded fluorescent reporter containing a lysosomal hydrolase tandemly tagged with pH sensitive and insensitive fluorescent proteins, which can spatiotemporally trace the trafficking of lysosomal hydrolases. As a proof of principle, we demonstrate that the reporter can detect perturbations in hydrolase trafficking, that are induced by pharmacological manipulations and pathophysiological conditions like intracellular protein aggregates. This reporter can effectively serve as a probe for mapping the mechanistic intricacies of hydrolase trafficking pathway in health and disease and is a utilitarian tool to identify genetic and pharmacological modulators of this pathway, with potential therapeutic implications.
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Affiliation(s)
- Mallika Bhat
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru 560064, India
| | - Akshaya Nambiar
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru 560064, India
| | | | - Irine Maria Abraham
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru 560064, India
| | - Ritoprova Sen
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru 560064, India
| | - Mamta Negi
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru 560064, India
| | - Ravi Manjithaya
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru 560064, India
- Professor and chair, Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru 560064, India
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Rachubik P, Rogacka D, Audzeyenka I, Typiak M, Wysocka M, Szrejder M, Lesner A, Piwkowska A. Role of lysosomes in insulin signaling and glucose uptake in cultured rat podocytes. Biochem Biophys Res Commun 2023; 679:145-159. [PMID: 37696068 DOI: 10.1016/j.bbrc.2023.09.012] [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: 07/07/2023] [Revised: 08/30/2023] [Accepted: 09/05/2023] [Indexed: 09/13/2023]
Abstract
Podocytes are sensitive to insulin, which governs the functional and structural integrity of podocytes that are essential for proper function of the glomerular filtration barrier. Lysosomes are acidic organelles that are implicated in regulation of the insulin signaling pathway. Cathepsin D (CTPD) and lysosome-associated membrane protein 1 (LAMP1) are major lysosomal proteins that reflect the functional state of lysosomes. However, the effect of insulin on lysosome activity and role of lysosomes in the regulation of insulin-dependent glucose uptake in podocytes are unknown. Our studies showed that the short-term incubation of podocytes with insulin decreased LAMP1 and CTPD mRNA levels. Insulin and bafilomycin A1 reduced both the amounts of LAMP1 and CTPD proteins and activity of CTPD, which were associated with a decrease in the fluorescence intensity of lysosomes that were labeled with LysoTracker. Bafilomycin A1 inhibited insulin-dependent endocytosis of the insulin receptor and increased the amounts of the insulin receptor and glucose transporter 4 on the cell surface of podocytes. Bafilomycin A1 also inhibited insulin-dependent glucose uptake despite an increase in the amount of glucose transporter 4 in the plasma membrane of podocytes. These results suggest that lysosomes are signaling hubs that may be involved in the coupling of insulin signaling with the regulation of glucose uptake in podocytes. The dysregulation of this mechanism can lead to the dysfunction of podocytes and development of insulin resistance.
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Affiliation(s)
- Patrycja Rachubik
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza 63 St, Gdansk, 80-308, Poland.
| | - Dorota Rogacka
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza 63 St, Gdansk, 80-308, Poland; Faculty of Chemistry, University of Gdansk, Wita Stwosza 63 St, Gdansk, 80-308, Poland.
| | - Irena Audzeyenka
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza 63 St, Gdansk, 80-308, Poland; Faculty of Chemistry, University of Gdansk, Wita Stwosza 63 St, Gdansk, 80-308, Poland.
| | - Marlena Typiak
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59 St, Gdansk, 80-308, Poland.
| | - Magdalena Wysocka
- Faculty of Chemistry, University of Gdansk, Wita Stwosza 63 St, Gdansk, 80-308, Poland.
| | - Maria Szrejder
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza 63 St, Gdansk, 80-308, Poland.
| | - Adam Lesner
- Faculty of Chemistry, University of Gdansk, Wita Stwosza 63 St, Gdansk, 80-308, Poland.
| | - Agnieszka Piwkowska
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza 63 St, Gdansk, 80-308, Poland; Faculty of Chemistry, University of Gdansk, Wita Stwosza 63 St, Gdansk, 80-308, Poland.
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Bhattacharya S, Yin J, Huo W, Chaum E. Modeling of mitochondrial bioenergetics and autophagy impairment in MELAS-mutant iPSC-derived retinal pigment epithelial cells. Stem Cell Res Ther 2022; 13:260. [PMID: 35715869 PMCID: PMC9205099 DOI: 10.1186/s13287-022-02937-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 04/30/2022] [Indexed: 11/13/2022] Open
Abstract
Background Mitochondrial dysfunction and mitochondrial DNA (mtDNA) damage in the retinal pigment epithelium (RPE) have been implicated in the pathogenesis of age-related macular degeneration (AMD). However, a deeper understanding is required to determine the contribution of mitochondrial dysfunction and impaired mitochondrial autophagy (mitophagy) to RPE damage and AMD pathobiology. In this study, we model the impact of a prototypical systemic mitochondrial defect, mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), in RPE health and homeostasis as an in vitro model for impaired mitochondrial bioenergetics. Methods We used induced pluripotent stem cells (iPSCs) derived from skin biopsies of MELAS patients (m.3243A > G tRNA leu mutation) with different levels of mtDNA heteroplasmy and differentiated them into RPE cells. Mitochondrial depletion of ARPE-19 cells (p0 cells) was also performed using 50 ng/mL ethidium bromide (EtBr) and 50 mg/ml uridine. Cell fusion of the human platelets with the p0 cells performed using polyethylene glycol (PEG)/suspension essential medium (SMEM) mixture to generate platelet/RPE “cybrids.” Confocal microscopy, FLowSight Imaging cytometry, and Seahorse XF Mito Stress test were used to analyze mitochondrial function. Western Blotting was used to analyze expression of autophagy and mitophagy proteins. Results We found that MELAS iPSC-derived RPE cells exhibited key characteristics of native RPE. We observed heteroplasmy-dependent impairment of mitochondrial bioenergetics and reliance on glycolysis for generating energy in the MELAS iPSC-derived RPE. The degree of heteroplasmy was directly associated with increased activation of signal transducer and activator of transcription 3 (STAT3), reduced adenosine monophosphate-activated protein kinase α (AMPKα) activation, and decreased autophagic activity. In addition, impaired autophagy was associated with aberrant lysosomal function, and failure of mitochondrial recycling. The mitochondria-depleted p0 cells replicated the effects on autophagy impairment and aberrant STAT3/AMPKα signaling and showed reduced mitochondrial respiration, demonstrating phenotypic similarities between p0 and MELAS iPSC-derived RPE cells. Conclusions Our studies demonstrate that the MELAS iPSC-derived disease models are powerful tools for dissecting the molecular mechanisms by which mitochondrial DNA alterations influence RPE function in aging and macular degeneration, and for testing novel therapeutics in patients harboring the MELAS genotype. Supplementary Information The online version contains supplementary material available at 10.1186/s13287-022-02937-6.
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Affiliation(s)
- Sujoy Bhattacharya
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, 2311 Pierce Avenue, Nashville, TN, 37232, USA
| | - Jinggang Yin
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, 2311 Pierce Avenue, Nashville, TN, 37232, USA
| | - Weihong Huo
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, 2311 Pierce Avenue, Nashville, TN, 37232, USA
| | - Edward Chaum
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, 2311 Pierce Avenue, Nashville, TN, 37232, USA.
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Carro SD, Cherry S. Beyond the Surface: Endocytosis of Mosquito-Borne Flaviviruses. Viruses 2020; 13:E13. [PMID: 33374822 PMCID: PMC7824540 DOI: 10.3390/v13010013] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/16/2020] [Accepted: 12/19/2020] [Indexed: 02/06/2023] Open
Abstract
Flaviviruses are a group of positive-sense RNA viruses that are primarily transmitted through arthropod vectors and are capable of causing a broad spectrum of diseases. Many of the flaviviruses that are pathogenic in humans are transmitted specifically through mosquito vectors. Over the past century, many mosquito-borne flavivirus infections have emerged and re-emerged, and are of global importance with hundreds of millions of infections occurring yearly. There is a need for novel, effective, and accessible vaccines and antivirals capable of inhibiting flavivirus infection and ameliorating disease. The development of therapeutics targeting viral entry has long been a goal of antiviral research, but most efforts are hindered by the lack of broad-spectrum potency or toxicities associated with on-target effects, since many host proteins necessary for viral entry are also essential for host cell biology. Mosquito-borne flaviviruses generally enter cells by clathrin-mediated endocytosis (CME), and recent studies suggest that a subset of these viruses can be internalized through a specialized form of CME that has additional dependencies distinct from canonical CME pathways, and antivirals targeting this pathway have been discovered. In this review, we discuss the role and contribution of endocytosis to mosquito-borne flavivirus entry as well as consider past and future efforts to target endocytosis for therapeutic interventions.
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Affiliation(s)
| | - Sara Cherry
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA;
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5
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Bond M, Chu L, Nalawansha DA, Li K, Crews CM. Targeted Degradation of Oncogenic KRAS G12C by VHL-Recruiting PROTACs. ACS CENTRAL SCIENCE 2020; 6:1367-1375. [PMID: 32875077 PMCID: PMC7453568 DOI: 10.1021/acscentsci.0c00411] [Citation(s) in RCA: 218] [Impact Index Per Article: 54.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Indexed: 05/16/2023]
Abstract
KRAS is mutated in ∼20% of human cancers and is one of the most sought-after targets for pharmacological modulation, despite having historically been considered "undruggable." The discovery of potent covalent inhibitors of the KRASG12C mutant in recent years has sparked a new wave of interest in small molecules targeting KRAS. While these inhibitors have shown promise in the clinic, we wanted to explore PROTAC-mediated degradation as a complementary strategy to modulate mutant KRAS. Herein, we report the development of LC-2, the first PROTAC capable of degrading endogenous KRASG12C. LC-2 covalently binds KRASG12C with a MRTX849 warhead and recruits the E3 ligase VHL, inducing rapid and sustained KRASG12C degradation leading to suppression of MAPK signaling in both homozygous and heterozygous KRASG12C cell lines. LC-2 demonstrates that PROTAC-mediated degradation is a viable option for attenuating oncogenic KRAS levels and downstream signaling in cancer cells.
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Affiliation(s)
- Michael
J. Bond
- Department
of Pharmacology, Yale University, New Haven, Connecticut 06511, United States
| | - Ling Chu
- Department
of Molecular, Cellular, and Developmental Biology, Yale University, 260 Whitney Avenue, New Haven, Connecticut 06511, United States
| | - Dhanusha A. Nalawansha
- Department
of Molecular, Cellular, and Developmental Biology, Yale University, 260 Whitney Avenue, New Haven, Connecticut 06511, United States
| | - Ke Li
- Department
of Molecular, Cellular, and Developmental Biology, Yale University, 260 Whitney Avenue, New Haven, Connecticut 06511, United States
| | - Craig M. Crews
- Department
of Pharmacology, Yale University, New Haven, Connecticut 06511, United States
- Department
of Molecular, Cellular, and Developmental Biology, Yale University, 260 Whitney Avenue, New Haven, Connecticut 06511, United States
- Department
of Chemistry, Yale University, New Haven, Connecticut 06511, United States
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6
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Song X, Akasaka H, Wang H, Abbasgholizadeh R, Shin JH, Zang F, Chen J, Logsdon CD, Maitra A, Bean AJ, Wang H. Hematopoietic progenitor kinase 1 down-regulates the oncogenic receptor tyrosine kinase AXL in pancreatic cancer. J Biol Chem 2020; 295:2348-2358. [PMID: 31959629 DOI: 10.1074/jbc.ra119.012186] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 01/14/2020] [Indexed: 12/23/2022] Open
Abstract
The oncogenic receptor tyrosine kinase AXL is overexpressed in cancer and plays an important role in carcinomas of multiple organs. However, the mechanisms of AXL overexpression in cancer remain unclear. In this study, using HEK293T, Panc-1, and Panc-28 cells and samples of human pancreatic intraepithelial neoplasia (PanIN), along with several biochemical approaches and immunofluorescence microscopy analyses, we sought to investigate the mechanisms that regulate AXL over-expression in pancreatic ductal adenocarcinoma (PDAC). We found that AXL interacts with hematopoietic progenitor kinase 1 (HPK1) and demonstrate that HPK1 down-regulates AXL and decreases its half-life. The HPK1-mediated AXL degradation was inhibited by the endocytic pathway inhibitors leupeptin, bafilomycin A1, and monensin. HPK1 accelerated the movement of AXL from the plasma membrane to endosomes in pancreatic cancer cells treated with the AXL ligand growth arrest-specific 6 (GAS6). Moreover, HPK1 increased the binding of AXL to the Cbl proto-oncogene (c-Cbl); promoted AXL ubiquitination; decreased AXL-mediated signaling, including phospho-AKT and phospho-ERK signaling; and decreased the invasion capability of PDAC cells. Importantly, we show that AXL expression inversely correlates with HPK1 expression in human PanINs and that patients whose tumors have low HPK1 and high AXL expression levels have shorter survival than those with low AXL or high HPK1 expression (p < 0.001). Our results suggest that HPK1 is a tumor suppressor that targets AXL for degradation via the endocytic pathway. HPK1 loss of function may contribute to AXL overexpression and thereby enhance AXL-dependent downstream signaling and tumor invasion in PDAC.
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Affiliation(s)
- Xianzhou Song
- Department of Anatomical Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Hironari Akasaka
- Department of Anatomical Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Hua Wang
- Department of Gastrointestinal Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Reza Abbasgholizadeh
- Department of Anatomical Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Ji-Hyun Shin
- Department of Anatomical Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Fenglin Zang
- Department of Anatomical Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Jiayi Chen
- Department of Anatomical Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Craig D Logsdon
- Department of Cancer Biology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Anirban Maitra
- Department of Anatomical Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030; Department of Translational Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Andrew J Bean
- Department of Neurobiology and Anatomy, University of Texas McGovern Medical School, Houston, Texas 77030
| | - Huamin Wang
- Department of Anatomical Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030; Department of Translational Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030.
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7
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Tan HWS, Anjum B, Shen HM, Ghosh S, Yen PM, Sinha RA. Lysosomal inhibition attenuates peroxisomal gene transcription via suppression of PPARA and PPARGC1A levels. Autophagy 2019; 15:1455-1459. [PMID: 31032705 DOI: 10.1080/15548627.2019.1609847] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Lysosomes influence dynamic cellular processes such as nutrient sensing and transcriptional regulation. To explore novel transcriptional pathways regulated by lysosomes, we performed microarray analysis followed by qPCR validation in a mouse hepatocyte cell line, AML12, treated with bafilomycin A1 (lysosomal v-type H+-translocating ATPase inhibitor). Pathway enrichment analysis revealed significant downregulation of gene sets related to peroxisomal biogenesis and peroxisomal lipid oxidation upon lysosomal inhibition. Mechanistically, pharmacological inhibition of lysosomes as well as genetic knockdown of Tfeb led to downregulation of the peroxisomal master regulator PPARA and its coactivator PPARGC1A/PGC1α. Consistently, ectopic induction of PPARA transcriptional activity rescues the effects of lysosomal inhibition on peroxisomal gene expression. Collectively, our results uncover a novel metabolic regulation of peroxisomes by lysosomes via PPARA-PPARGC1A transcriptional signalling. Abbreviations: Acox1: acyl-Coenzyme A oxidase 1, palmitoyl; Acot: acyl-CoA thioesterase; ACAA: acetyl-Coenzyme A acyltransferase; ABCD3/PMP70: ATP-binding cassette, sub-family D (ALD), member 3; BafA1: bafilomycin A1; Crot: carnitine O-octanoyltransferase; CTSB: cathepsin B; Decr2: 2-4-dienoyl-Coenzyme A reductase 2, peroxisomal; Ech1: enoyl coenzyme A hydratase 1, peroxisomal; Ehhadh: enoyl-Coenzyme A, hydratase/3-hydroxyacyl Coenzyme A dehydrogenase; FDR: false discovery rate; Hsd17b4: hydroxysteroid (17-beta) dehydrogenase 4; NES: normalized enrichment score; NOM: nominal; Pex: peroxin; PPARA: peroxisome proliferator activated receptor alpha; PPARGC1A: peroxisome proliferator activated receptor, gamma, coactivator 1 alpha; TFEB: transcription factor EB.
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Affiliation(s)
- Hayden Weng Siong Tan
- a Department of Physiology , Yong Loo Lin School of Medicine, National University of Singapore , Singapore , Singapore.,b Program of Cardiovascular and Metabolic Disorders , Duke-NUS Medical School , Singapore , Singapore.,c School for Integrative Sciences and Engineering, National University of Singapore , Singapore , Singapore
| | - B Anjum
- d Department of Endocrinology , Sanjay Gandhi Postgraduate Institute of Medical Sciences , Lucknow , India
| | - Han-Ming Shen
- a Department of Physiology , Yong Loo Lin School of Medicine, National University of Singapore , Singapore , Singapore.,c School for Integrative Sciences and Engineering, National University of Singapore , Singapore , Singapore
| | - Sujoy Ghosh
- b Program of Cardiovascular and Metabolic Disorders , Duke-NUS Medical School , Singapore , Singapore
| | - Paul M Yen
- b Program of Cardiovascular and Metabolic Disorders , Duke-NUS Medical School , Singapore , Singapore
| | - Rohit A Sinha
- d Department of Endocrinology , Sanjay Gandhi Postgraduate Institute of Medical Sciences , Lucknow , India
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Tsujita N, Kuwahara H, Koyama H, Yanaka N, Arakawa K, Kuniyoshi H. Molecular characterization of aspartylglucosaminidase, a lysosomal hydrolase upregulated during strobilation in the moon jellyfish, Aurelia aurita. Biosci Biotechnol Biochem 2017; 81:938-950. [PMID: 28388360 DOI: 10.1080/09168451.2017.1285686] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The life cycle of the moon jellyfish, Aurelia aurita, alternates between a benthic asexual polyp stage and a planktonic sexual medusa (jellyfish) stage. Transition from polyp to medusa is called strobilation. To investigate the molecular mechanisms of strobilation, we screened for genes that are upregulated during strobilation using the differential display method and we identified aspartylglucosaminidase (AGA), which encodes a lysosomal hydrolase. Similar to AGAs from other species, Aurelia AGA possessed an N-terminal signal peptide and potential N-glycosylation sites. The genomic region of Aurelia AGA was approximately 9.8 kb in length and contained 12 exons and 11 introns. Quantitative RT-PCR analysis revealed that AGA expression increased during strobilation, and was then decreased in medusae. To inhibit AGA function, we administered the lysosomal acidification inhibitors, chloroquine or bafilomycin A1, to animals during strobilation. Both inhibitors disturbed medusa morphogenesis at the oral end, suggesting involvement of lysosomal hydrolases in strobilation.
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Affiliation(s)
- Natsumi Tsujita
- a Graduate School of Biosphere Science , Hiroshima University , Higashi-Hiroshima , Japan
| | - Hiroyuki Kuwahara
- a Graduate School of Biosphere Science , Hiroshima University , Higashi-Hiroshima , Japan
| | - Hiroki Koyama
- a Graduate School of Biosphere Science , Hiroshima University , Higashi-Hiroshima , Japan
| | - Noriyuki Yanaka
- a Graduate School of Biosphere Science , Hiroshima University , Higashi-Hiroshima , Japan
| | - Kenji Arakawa
- b Graduate School of Advanced Sciences of Matter , Hiroshima University , Higashi-Hiroshima , Japan
| | - Hisato Kuniyoshi
- a Graduate School of Biosphere Science , Hiroshima University , Higashi-Hiroshima , Japan
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Neurovirulent Murine Coronavirus JHM.SD Uses Cellular Zinc Metalloproteases for Virus Entry and Cell-Cell Fusion. J Virol 2017; 91:JVI.01564-16. [PMID: 28148786 DOI: 10.1128/jvi.01564-16] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 01/24/2017] [Indexed: 12/27/2022] Open
Abstract
The coronavirus (CoV) S protein requires cleavage by host cell proteases to mediate virus-cell and cell-cell fusion. Many strains of the murine coronavirus mouse hepatitis virus (MHV) have distinct, S-dependent organ and tissue tropisms despite using a common receptor, suggesting that they employ different cellular proteases for fusion. In support of this hypothesis, we found that inhibition of endosomal acidification only modestly decreased entry, and overexpression of the cell surface protease TMPRSS2 greatly enhanced entry, of the highly neurovirulent MHV strain JHM.SD relative to their effects on the reference strain, A59. However, TMPRSS2 overexpression decreased MHV structural protein expression, release of infectious particles, and syncytium formation, and endogenous serine protease activity did not contribute greatly to infection. We therefore investigated the importance of other classes of cellular proteases and found that inhibition of matrix metalloproteinase (MMP)- and a disintegrin and metalloprotease (ADAM)-family zinc metalloproteases markedly decreased both entry and cell-cell fusion. Suppression of virus by metalloprotease inhibition varied among tested cell lines and MHV S proteins, suggesting a role for metalloprotease use in strain-dependent tropism. We conclude that zinc metalloproteases must be considered potential contributors to coronavirus fusion.IMPORTANCE The family Coronaviridae includes viruses that cause two emerging diseases of humans, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), as well as a number of important animal pathogens. Because coronaviruses depend on host protease-mediated cleavage of their S proteins for entry, a number of protease inhibitors have been proposed as antiviral agents. However, it is unclear which proteases mediate in vivo infection. For example, SARS-CoV infection of cultured cells depends on endosomal acid pH-dependent proteases rather than on the cell surface acid pH-independent serine protease TMPRSS2, but Zhou et al. (Antiviral Res 116:76-84, 2015, doi:10.1016/j.antiviral.2015.01.011) found that a serine protease inhibitor was more protective than a cathepsin inhibitor in SARS-CoV-infected mice. This paper explores the contributions of endosomal acidification and various proteases to coronavirus infection and identifies an unexpected class of proteases, the matrix metalloproteinase and ADAM families, as potential targets for anticoronavirus therapy.
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Yamasaki T, Suzuki A, Hasebe R, Horiuchi M. Comparison of the anti-prion mechanism of four different anti-prion compounds, anti-PrP monoclonal antibody 44B1, pentosan polysulfate, chlorpromazine, and U18666A, in prion-infected mouse neuroblastoma cells. PLoS One 2014; 9:e106516. [PMID: 25181483 PMCID: PMC4152300 DOI: 10.1371/journal.pone.0106516] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 08/04/2014] [Indexed: 01/07/2023] Open
Abstract
Molecules that inhibit the formation of an abnormal isoform of prion protein (PrPSc) in prion-infected cells are candidate therapeutic agents for prion diseases. Understanding how these molecules inhibit PrPSc formation provides logical basis for proper evaluation of their therapeutic potential. In this study, we extensively analyzed the effects of the anti-PrP monoclonal antibody (mAb) 44B1, pentosan polysulfate (PPS), chlorpromazine (CPZ) and U18666A on the intracellular dynamics of a cellular isoform of prion protein (PrPC) and PrPSc in prion-infected mouse neuroblastoma cells to re-evaluate the effects of those agents. MAb 44B1 and PPS rapidly reduced PrPSc levels without altering intracellular distribution of PrPSc. PPS did not change the distribution and levels of PrPC, whereas mAb 44B1 appeared to inhibit the trafficking of cell surface PrPC to organelles in the endocytic-recycling pathway that are thought to be one of the sites for PrPSc formation. In contrast, CPZ and U18666A initiated the redistribution of PrPSc from organelles in the endocytic-recycling pathway to late endosomes/lysosomes without apparent changes in the distribution of PrPC. The inhibition of lysosomal function by monensin or bafilomycin A1 after the occurrence of PrPSc redistribution by CPZ or U18666A partly antagonized PrPSc degradation, suggesting that the transfer of PrPSc to late endosomes/lysosomes, possibly via alteration of the membrane trafficking machinery of cells, leads to PrPSc degradation. This study revealed that precise analysis of the intracellular dynamics of PrPC and PrPSc provides important information for understanding the mechanism of anti-prion agents.
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Affiliation(s)
- Takeshi Yamasaki
- Laboratory of Veterinary Hygiene, Graduate School of Veterinary Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Akio Suzuki
- Laboratory of Veterinary Hygiene, Graduate School of Veterinary Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Rie Hasebe
- Laboratory of Veterinary Hygiene, Graduate School of Veterinary Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Motohiro Horiuchi
- Laboratory of Veterinary Hygiene, Graduate School of Veterinary Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
- * E-mail:
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Katayama K, Noguchi K, Sugimoto Y. FBXO15 regulates P-glycoprotein/ABCB1 expression through the ubiquitin--proteasome pathway in cancer cells. Cancer Sci 2013; 104:694-702. [PMID: 23465077 DOI: 10.1111/cas.12145] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 02/27/2013] [Accepted: 03/01/2013] [Indexed: 12/25/2022] Open
Abstract
Expression of P-glycoprotein (P-gp)/ABCB1 on cancer cell surfaces is a critical determinant of anticancer drug resistance. Regulators of P-gp expression and function are key molecules controlling drug resistance. Here we report the mechanism underlying the ubiquitin-proteasome pathway-mediated degradation of P-gp. The proteasome inhibitor MG132 increased the P-gp level, enhanced its ubiquitination, and delayed the disappearance of the ubiquitinated P-gp. To search for regulators of P-gp ubiquitination, MALDI-time of flight mass spectrometry analyses were carried out, and 22 candidates were identified as P-gp binding partners. Among them, FBXO15/Fbx15 is known as an F-box protein in the ubiquitin E3 ligase complex, Skp1-Cullin1-FBXO15 (SCF(Fbx15) ); therefore, we further studied the involvement of FBXO15 on P-gp degradation. Coprecipitation assays revealed that FBXO15 bound to P-gp. We screened ubiquitin-conjugating enzyme E2s that bind to FBXO15 and P-gp; Ube2r1/Cdc34/Ubc3 was found to be a binding partner. Exogenous FBXO15 expression enhanced P-gp ubiquitination, but FBXO15 knockdown suppressed it. FBXO15 knockdown increased P-gp expression without affecting its mRNA level. Ube2r1 knockdown decreased P-gp ubiquitination, and simultaneous knockdown of Ube2r1 with FBXO15 further suppressed the ubiquitination. Ube2r1 knockdown increased P-gp expression, suggesting that Ube2r1 is a partner of FBXO15 in P-gp ubiquitination. FBXO15 knockdown enhanced vincristine resistance and lowered intracellular levels of rhodamine 123. These data suggest that FBXO15 and Ube2r1 regulate P-gp expression through the ubiquitin-proteasome pathway.
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Affiliation(s)
- Kazuhiro Katayama
- Division of Chemotherapy, Faculty of Pharmacy, Keio University, Tokyo, Japan
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12
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Dysfunction of autophagy participates in vacuole formation and cell death in cells replicating hepatitis C virus. J Virol 2011; 85:13185-94. [PMID: 21994453 DOI: 10.1128/jvi.06099-11] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Hepatitis C virus (HCV) is a major cause of chronic liver diseases. A high risk of chronicity is the major concern of HCV infection, since chronic HCV infection often leads to liver cirrhosis and hepatocellular carcinoma. Infection with the HCV genotype 1 in particular is considered a clinical risk factor for the development of hepatocellular carcinoma, although the molecular mechanisms of the pathogenesis are largely unknown. Autophagy is involved in the degradation of cellular organelles and the elimination of invasive microorganisms. In addition, disruption of autophagy often leads to several protein deposition diseases. Although recent reports suggest that HCV exploits the autophagy pathway for viral propagation, the biological significance of the autophagy to the life cycle of HCV is still uncertain. Here, we show that replication of HCV RNA induces autophagy to inhibit cell death. Cells harboring an HCV replicon RNA of genotype 1b strain Con1 but not of genotype 2a strain JFH1 exhibited an incomplete acidification of the autolysosome due to a lysosomal defect, leading to the enhanced secretion of immature cathepsin B. The suppression of autophagy in the Con1 HCV replicon cells induced severe cytoplasmic vacuolation and cell death. These results suggest that HCV harnesses autophagy to circumvent the harmful vacuole formation and to maintain a persistent infection. These findings reveal a unique survival strategy of HCV and provide new insights into the genotype-specific pathogenicity of HCV.
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Yasir M, Pachikara ND, Bao X, Pan Z, Fan H. Regulation of chlamydial infection by host autophagy and vacuolar ATPase-bearing organelles. Infect Immun 2011; 79:4019-28. [PMID: 21807906 PMCID: PMC3187247 DOI: 10.1128/iai.05308-11] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 07/20/2011] [Indexed: 11/20/2022] Open
Abstract
As arguably the most successful parasite, Chlamydia is an obligate intracellular bacterium replicating inside a vacuole of eukaryotic host cells. The chlamydial vacuole does not fuse with the defense cell organelle lysosome. We previously showed that chlamydial infection increases markers of autophagy, an innate antimicrobial activity requiring lysosomal function. However, the work presented here demonstrates that p62, an autophagy protein that is degraded in lysosomes, either remained unchanged or increased in chlamydia-infected human epithelial, mouse fibroblast, and mouse macrophage cell lines. In addition, the activities of three lysosomal enzymes analyzed were diminished in chlamydia-infected macrophages. Bafilomycin A1 (BafA), a specific inhibitor of vacuolar ATPase (vATPase) required for lysosomal function, increased the growth of the human pathogen Chlamydia trachomatis (L2) in wild-type murine fibroblasts and macrophages but inhibited growth in the autophagy-deficient ATG5(-/-) fibroblasts. BafA exhibited only slight inhibition or no effect on L2 growth in multiple human genital epithelial cell lines. In contrast to L2, the mouse pathogen Chlamydia muridarum (MoPn) was consistently inhibited by BafA in all cell lines examined, regardless of species origin and autophagy status. Finally, L2 but not MoPn grew more efficiently in the ATG5(-/-) cells than in wild-type cells. These results suggest that there are two types of vATPase-bearing organelles that regulate chlamydial infection: one supports chlamydial infection, while the other plays a defensive role through autophagy when cells are artificially infected with certain chlamydiae that have not been adapted to the host species.
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Affiliation(s)
| | | | | | - Zui Pan
- Department of Physiology and Biophysics, Robert Wood Johnson Medical School, 683 Hoes Lane, Piscataway, New Jersey 08854
| | - Huizhou Fan
- Department of Physiology and Biophysics, Robert Wood Johnson Medical School, 683 Hoes Lane, Piscataway, New Jersey 08854
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Gillis JM, Benckhuijsen W, van Veen H, Sanz AS, Drijfhout JW, Reits EA. Aminopeptidase-Resistant Peptides Are Targeted to Lysosomes and Subsequently Degraded. Traffic 2011; 12:1897-910. [DOI: 10.1111/j.1600-0854.2011.01270.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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15
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Wei Z, Biswas N, Wang L, Courel M, Zhang K, Soler-Jover A, Taupenot L, O'Connor DT. A common genetic variant in the 3'-UTR of vacuolar H+-ATPase ATP6V0A1 creates a micro-RNA motif to alter chromogranin A processing and hypertension risk. ACTA ACUST UNITED AC 2011; 4:381-9. [PMID: 21558123 DOI: 10.1161/circgenetics.111.959767] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND The catecholamine release-inhibitor catestatin and its precursor chromogranin A (CHGA) may constitute "intermediate phenotypes" in the analysis of genetic risk for cardiovascular disease such as hypertension. Previously, the vacuolar H(+)-ATPase subunit gene ATP6V0A1 was found within the confidence interval for linkage with catestatin secretion in a genome-wide study, and its 3'-UTR polymorphism T+3246C (rs938671) was associated with both catestatin processing from CHGA and population blood pressure. We explored the molecular mechanism of this effect by experiments with transfected chimeric photoproteins in chromaffin cells. METHODS AND RESULTS Placing the ATP6V0A1 3'-UTR downstream of a luciferase reporter, we found that the C (variant) allele decreased overall gene expression. The 3'-UTR effect was verified by coupled in vitro transcription/translation of the entire/intact human ATP6V0A1 mRNA. Chromaffin granule pH, monitored by fluorescence of CHGA/EGFP chimera during vesicular H(+)-ATPase inhibition by bafilomycin A1, was more easily perturbed during coexpression of the ATP6V0A1 3'-UTR C-allele than the T-allele. After bafilomycin A1 treatment, the ratio of CHGA precursor to its catestatin fragments in PC12 cells was substantially diminished, though the qualitative composition of such fragments was not affected (on immunoblot or matrix-assisted laser desorption ionization (MALDI) mass spectrometry). Bafilomycin A1 treatment also decreased exocytotic secretion from the regulated pathway, monitored by a CHGA chimera tagged with embryonic alkaline phosphatase. 3'-UTR T+3246C created a binding motif for micro-RNA hsa-miR-637; cotransfection of hsa-miR-637 precursor or antagomir/inhibitor oligonucleotides yielded the predicted changes in expression of luciferase reporter/ATP6V0A1-3'-UTR plasmids varying at T+3246C. CONCLUSIONS The results suggest a series of events whereby ATP6V0A1 3'-UTR variant T+3246C functioned: ATP6V0A1 expression probably was affected through differential micro-RNA effects, altering vacuolar pH and consequently CHGA processing and exocytotic secretion.
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Affiliation(s)
- Zhiyun Wei
- Departments of Medicine and Pharmacology, Institute for Genomic Medicine, University of California at San Diego, the VA San Diego Healthcare System, La Jolla, USA
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16
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Yamasaki K, Muto J, Taylor KR, Cogen AL, Audish D, Bertin J, Grant EP, Coyle AJ, Misaghi A, Hoffman HM, Gallo RL. NLRP3/cryopyrin is necessary for interleukin-1beta (IL-1beta) release in response to hyaluronan, an endogenous trigger of inflammation in response to injury. J Biol Chem 2009; 284:12762-71. [PMID: 19258328 DOI: 10.1074/jbc.m806084200] [Citation(s) in RCA: 216] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Inflammation under sterile conditions is a key event in autoimmunity and following trauma. Hyaluronan, a glycosaminoglycan released from the extracellular matrix after injury, acts as an endogenous signal of trauma and can trigger chemokine release in injured tissue. Here, we investigated whether NLRP3/cryopyrin, a component of the inflammasome, participates in the inflammatory response to injury or the cytokine response to hyaluronan. Mice with a targeted deletion in cryopyrin showed a normal increase in Cxcl2 in response to sterile injuries but had decreased inflammation and release of interleukin-1beta (IL-1beta). Similarly, the addition of hyaluronan to macrophages derived from cryopyrin-deficient mice increased release of Cxcl2 but did not increase IL-1beta release. To define the mechanism of hyaluronan-mediated activation of cryopyrin, elements of the hyaluronan recognition process were studied in detail. IL-1beta release was inhibited in peritoneal macrophages derived from CD44-deficient mice, in an MH-S macrophage cell line treated with antibodies to CD44, or by inhibitors of lysosome function. The requirement for CD44 binding and hyaluronan internalization could be bypassed by intracellular administration of hyaluronan oligosaccharides (10-18-mer) in lipopolysaccharide-primed macrophages. Therefore, the action of CD44 and subsequent hyaluronan catabolism trigger the intracellular cryopyrin --> IL-1beta pathway. These findings support the hypothesis that hyaluronan works through IL-1beta and the cryopyrin system to signal sterile inflammation.
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Affiliation(s)
- Kenshi Yamasaki
- Division of Dermatology, University of California, and Veterans Affairs San Diego Health Care System, San Diego, CA 92161, USA
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17
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Tu C, Ortega-Cava CF, Chen G, Fernandes ND, Cavallo-Medved D, Sloane BF, Band V, Band H. Lysosomal cathepsin B participates in the podosome-mediated extracellular matrix degradation and invasion via secreted lysosomes in v-Src fibroblasts. Cancer Res 2008; 68:9147-56. [PMID: 19010886 PMCID: PMC2764335 DOI: 10.1158/0008-5472.can-07-5127] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Podosomes mediate cell migration and invasion by coordinating the reorganization of actin cytoskeleton and focal matrix degradation. MMP and serine proteases have been found to function at podosomes. The lysosomal cysteine cathepsins, a third major class of matrix-degrading enzymes involved in tumor invasion and tissue remodeling, have yet to be linked to podosomes with the exception of cathepsin K in osteoclasts. Using inhibitors and shRNA-mediated depletion, we show that cathepsin B participates in podosomes-mediated focal matrix degradation and invasion in v-Src-transformed fibroblasts. We observed that lysosomal marker LAMP-1 localized at the center of podosome rosettes protruding into extracellular matrix using confocal microscopy. Time-lapse live-cell imaging revealed that lysosomal vesicles moved to and fused with podosomes. Disruption of lysosomal pH gradient with Bafilomycin A1, chloroquine, or ammonium chloride greatly enhanced the formation of podosomes and increased the matrix degradation. Live-cell imaging showed that actin structures, induced shortly after Bafilomycin A1 treatment, were closely associated with lysosomes. Overall, our results suggest that cathepsin B, delivered by lysosomal vesicles, is involved in the matrix degradtion of podosomes.
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Affiliation(s)
- Chun Tu
- Eppley Institute for Research in Cancer and Allied Diseases, and UNMC-Eppley Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198-6805
- This work was initiated and substantially performed while the authors were at the Divisions of Molecular Oncology and Cancer Biology, Evanston Northwestern Healthcare Research Institute, Department of Medicine, Feinberg School of Medicine; Robert H. Lurie Comprehensive Cancer Center, and Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, IL 60201
| | - Cesar F. Ortega-Cava
- Eppley Institute for Research in Cancer and Allied Diseases, and UNMC-Eppley Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198-6805
- This work was initiated and substantially performed while the authors were at the Divisions of Molecular Oncology and Cancer Biology, Evanston Northwestern Healthcare Research Institute, Department of Medicine, Feinberg School of Medicine; Robert H. Lurie Comprehensive Cancer Center, and Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, IL 60201
| | - Gengsheng Chen
- This work was initiated and substantially performed while the authors were at the Divisions of Molecular Oncology and Cancer Biology, Evanston Northwestern Healthcare Research Institute, Department of Medicine, Feinberg School of Medicine; Robert H. Lurie Comprehensive Cancer Center, and Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, IL 60201
| | | | - Dora Cavallo-Medved
- Department of Pharmacology and Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI
| | - Bonnie F. Sloane
- Department of Pharmacology and Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI
| | - Vimla Band
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, and UNMC-Eppley Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198-5805
- This work was initiated and substantially performed while the authors were at the Divisions of Molecular Oncology and Cancer Biology, Evanston Northwestern Healthcare Research Institute, Department of Medicine, Feinberg School of Medicine; Robert H. Lurie Comprehensive Cancer Center, and Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, IL 60201
| | - Hamid Band
- Eppley Institute for Research in Cancer and Allied Diseases, and UNMC-Eppley Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198-6805
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Nebraska Medical Center, Omaha, NE 68198-5805
- This work was initiated and substantially performed while the authors were at the Divisions of Molecular Oncology and Cancer Biology, Evanston Northwestern Healthcare Research Institute, Department of Medicine, Feinberg School of Medicine; Robert H. Lurie Comprehensive Cancer Center, and Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, IL 60201
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18
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Frankenberg T, Kirschnek S, Häcker H, Häcker G. Phagocytosis-induced apoptosis of macrophages is linked to uptake, killing and degradation of bacteria. Eur J Immunol 2008; 38:204-15. [DOI: 10.1002/eji.200737379] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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19
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Yamatake K, Maeda M, Kadowaki T, Takii R, Tsukuba T, Ueno T, Kominami E, Yokota S, Yamamoto K. Role for gingipains in Porphyromonas gingivalis traffic to phagolysosomes and survival in human aortic endothelial cells. Infect Immun 2007; 75:2090-100. [PMID: 17296756 PMCID: PMC1865784 DOI: 10.1128/iai.01013-06] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Gingipains are cysteine proteinases that are responsible for the virulence of Porphyromonas gingivalis. Recent studies have shown that P. gingivalis is trapped within autophagic compartments of infected cells, where it promotes survival. In this study we investigated the role of gingipains in the intracellular trafficking and survival of this bacterium in human aortic endothelial cells and any possible involvement of these enzymes in the autophagic pathway. Although autophagic events were enhanced by infection with either wild-type (WT) P. gingivalis strains (ATCC 33277, 381, and W83) or an ATCC 33277 mutant lacking gingipains (KDP136), we have found that more than 90% of intracellular WT and KDP136 colocalized with cathepsin B, a lysosome marker, and only a few of the internalized cells colocalized with LC3, an autophagosome marker, during the 0.5- to 4-h postinfection period. This was further substantiated by immunogold electron microscopic analyses, thus implying that P. gingivalis evades the autophagic pathway and instead directly traffics to the endocytic pathway to lysosomes. At the late stages after infection, WT strains in phagolysosomes retained their double-membrane structures. KDP136 in these compartments, however, lost its double-membrane structures, representing a characteristic feature of its vulnerability to rupture. Together with the ultrastructural observations, we found that the number of intracellular viable WT cells decreased more slowly than that of KDP136 cells, thus suggesting that gingipains contribute to bacterial survival, but not to trafficking, within the infected cells.
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Affiliation(s)
- Kumiko Yamatake
- Department of Pharmacology, Graduate School of Dental Science, Kyushu University, Fukuoka 812-8582, Japan
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20
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Yanagawa M, Tsukuba T, Nishioku T, Okamoto Y, Okamoto K, Takii R, Terada Y, Nakayama KI, Kadowaki T, Yamamoto K. Cathepsin E Deficiency Induces a Novel Form of Lysosomal Storage Disorder Showing the Accumulation of Lysosomal Membrane Sialoglycoproteins and the Elevation of Lysosomal pH in Macrophages. J Biol Chem 2007; 282:1851-62. [PMID: 17095504 DOI: 10.1074/jbc.m604143200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cathepsin E, an endolysosomal aspartic proteinase predominantly expressed in cells of the immune system, has an important role in immune responses. However, little is known about the precise roles of cathepsin E in this system. Here we report that cathepsin E deficiency (CatE(-/-)) leads to a novel form of lysosome storage disorder in macrophages, exhibiting the accumulation of the two major lysosomal membrane sialoglycoproteins LAMP-1 and LAMP-2 and the elevation of lysosomal pH. These striking features were also found in wild-type macrophages treated with pepstatin A and Ascaris inhibitor. Whereas there were no obvious differences in their expression, biosynthesis, and trafficking between wild-type and CatE(-/-) macrophages, the degradation rates of these two membrane proteins were apparently decreased as a result of cathepsin E deficiency. Because there was no difference in the vacuolar-type H(+)-ATPase activity in both cell types, the elevated lysosomal pH in CatE(-/-) macrophages is most likely due to the accumulation of these lysosomal membrane glycoproteins highly modified with acidic monosaccharides, thereby leading to the disruption of non-proton factors controlling lysosomal pH. Furthermore, the selective degradation of LAMP-1 and LAMP-2, as well as LIMP-2, was also observed by treatment of the lysosomal membrane fraction isolated from wild-type macrophages with purified cathepsin E at pH 5. Our results thus suggest that cathepsin E is important for preventing the accumulation of these lysosomal membrane sialoglycoproteins that can induce a new form of lysosomal storage disorder.
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Affiliation(s)
- Michiyo Yanagawa
- Department of Pharmacology, Graduate School of Dental Science, Kyushu University, Fukuoka, Japan
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21
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Erickson HK, Park PU, Widdison WC, Kovtun YV, Garrett LM, Hoffman K, Lutz RJ, Goldmacher VS, Blättler WA. Antibody-maytansinoid conjugates are activated in targeted cancer cells by lysosomal degradation and linker-dependent intracellular processing. Cancer Res 2006; 66:4426-33. [PMID: 16618769 DOI: 10.1158/0008-5472.can-05-4489] [Citation(s) in RCA: 414] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Antibody-drug conjugates are targeted anticancer agents consisting of a cytotoxic drug covalently linked to a monoclonal antibody for tumor antigen-specific activity. Once bound to the target cell-surface antigen, the conjugate must be processed to release an active form of the drug, which can reach its intracellular target. Here, we used both biological and biochemical methods to better define this process for antibody-maytansinoid conjugates. In particular, we examined the metabolic fate in cells of huC242-maytansinoid conjugates containing either a disulfide linker (huC242-SPDB-DM4) or a thioether linker (huC242-SMCC-DM1). Using cell cycle analysis combined with lysosomal inhibitors, we showed that lysosomal processing is required for the activity of antibody-maytansinoid conjugates, irrespective of the linker. We also identified and characterized the released maytansinoid molecules from these conjugates, and measured their rate of release compared with the kinetics of cell cycle arrest. Both conjugates are efficiently degraded in lysosomes to yield metabolites consisting of the intact maytansinoid drug and linker attached to lysine. The lysine adduct is the sole metabolite from the thioether-linked conjugate. However, the lysine metabolite generated from the disulfide-linked conjugate is reduced and S-methylated to yield the lipophilic and potently cytotoxic metabolite, S-methyl-DM4. These findings provide insight into the mechanism of action of antibody-maytansinoid conjugates in general, and more specifically, identify a biochemical mechanism that may account for the significantly enhanced antitumor efficacy observed with disulfide-linked conjugates.
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Lecaille F, Muno D, Kominami E, Ishidoh K. Proteinases participating in the processing and activation of prolegumain in primary cultured rat macrophages. Biol Chem 2005; 385:511-6. [PMID: 15255183 DOI: 10.1515/bc.2004.060] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The mammalian legumain is a recently identified lysosomal cysteine proteinase belonging to the clan CD and homologous to plant legumain. This enzyme has the characteristic of specifically hydrolyzing peptide bonds after asparagine residues. As in the case of papain-type cysteine proteinases, legumain is synthesized as an inactive zymogen, and processed into a mature form localized in lysosomes. However, the mechanism of its activation remains unclear. In this study, we analyze which types of proteinases may participate in the processing of legumain in rat primary cultured macrophages using various proteinase inhibitors after 24 h treatment with Bafilomycin A1, a vacuolar ATPase inhibitor. The processing of legumain in macrophages was accomplished by papain-type cysteine proteinases other than cathepsin B.
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Affiliation(s)
- Fabien Lecaille
- Department of Biochemistry, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
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23
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Abstract
Acidification of some organelles, including the Golgi complex, lysosomes, secretory granules, and synaptic vesicles, is important for many of their biochemical functions. In addition, acidic pH in some compartments is also required for the efficient sorting and trafficking of proteins and lipids along the biosynthetic and endocytic pathways. Despite considerable study, however, our understanding of how pH modulates membrane traffic remains limited. In large part, this is due to the diversity of methods to perturb and monitor pH, as well as to the difficulties in isolating individual transport steps within the complex pathways of membrane traffic. This review summarizes old and recent evidence for the role of acidification at various steps of biosynthetic and endocytic transport in mammalian cells. We describe the mechanisms by which organelle pH is regulated and maintained, as well as how organelle pH is monitored and quantitated. General principles that emerge from these studies as well as future directions of interest are discussed.
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Affiliation(s)
- Ora A Weisz
- Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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Golabek AA, Kida E, Walus M, Wujek P, Mehta P, Wisniewski KE. Biosynthesis, glycosylation, and enzymatic processing in vivo of human tripeptidyl-peptidase I. J Biol Chem 2003; 278:7135-45. [PMID: 12488460 DOI: 10.1074/jbc.m211872200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Human tripeptidyl-peptidase I (TPP I, CLN2 protein) is a lysosomal serine protease that removes tripeptides from the free N termini of small polypeptides and also shows a minor endoprotease activity. Due to various naturally occurring mutations, an inherited deficiency of TPP I activity causes a fatal lysosomal storage disorder, classic late infantile neuronal ceroid lipofuscinosis (CLN2). In the present study, we analyzed biosynthesis, glycosylation, transport, and proteolytic processing of this enzyme in stably transfected Chinese hamster ovary cells as well as maturation of the endocytosed proenzyme in CLN2 lymphoblasts, fibroblasts, and N2a cells. Human TPP I was initially identified as a single precursor polypeptide of approximately 68 kDa, which, within a few hours, was converted to the mature enzyme of approximately 48 kDa. Compounds affecting the pH of intracellular acidic compartments, those interfering with the intracellular vesicular transport as well as inhibition of the fusion between late endosomes and lysosomes by temperature block or 3-methyladenine, hampered the conversion of TPP I proenzyme into the mature form, suggesting that this process takes place in lysosomal compartments. Digestion of immunoprecipitated TPP I proenzyme with both N-glycosidase F and endoglycosidase H as well as treatment of the cells with tunicamycin reduced the molecular mass of TPP I proenzyme by approximately 10 kDa, which indicates that all five potential N-glycosylation sites in TPP I are utilized. Mature TPP I was found to be partially resistant to endo H treatment; thus, some of its N-linked oligosaccharides are of the complex/hybrid type. Analysis of the effect of various classes of protease inhibitors and mutation of the active site Ser(475) on human TPP I maturation in cultured cells demonstrated that although TPP I zymogen is capable of autoactivation in vitro, a serine protease that is sensitive to AEBSF participates in processing of the proenzyme to the mature, active form in vivo.
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Affiliation(s)
- Adam A Golabek
- New York State Institute for Basic Research in Developmental Disabilities, Department of Developmental Neurobiology, Staten Island, New York 10314, USA.
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25
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Abstract
Lysosomal proteinases are translated as preproenzymes, transferred through the Golgi apparatus as proenzymes, and localized in lysosomes as the mature enzymes. Pulse-chase analyses and the immunoisolation of proenzymes or recombinant proenzymes are useful tools for analyzing this process, but the processing proteinases that participate in this pathway are largely unknown. Recently, we developed a new method for analyzing processing proteinases using Bafilomycin A1 and proteinase inhibitors. Here we summarize the recent progress including our results obtained using this method.
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Affiliation(s)
- Kazumi Ishidoh
- Department of Biochemistry, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
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26
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Yoshimoto Y, Imoto M. Induction of EGF-dependent apoptosis by vacuolar-type H(+)-ATPase inhibitors in A431 cells overexpressing the EGF receptor. Exp Cell Res 2002; 279:118-27. [PMID: 12213220 DOI: 10.1006/excr.2002.5588] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The stimulation of human tumor cells overexpressing epidermal growth factor receptor (EGFR) with EGF enhances tumor development and malignancy. Therefore, compounds that modulate the EGF-mediated signal inducing apoptosis in EGFR-overexpressing cells would represent a new class of antitumor drug and might be useful in the treatment of a subset of human tumors. In the course of screening for compounds that induce apoptosis in EGFR-overexpressing human epidermal carcinoma A431 cells from secondary metabolites of microorganisms, we found that vacuolar-type H(+)-ATPase (V-ATPase) inhibitors, such as concanamycin B and destruxin E, induced apoptosis only when the cells were stimulated with EGF. The EGF-dependent apoptosis by V-ATPase inhibitors was not observed in other types of human tumor cells which do not overexpress EGFR. The apoptosis in A431 cells was inhibited by anti-FasL antibody which neutralized the cytotoxic effect of FasL, indicating that the Fas/FasL system was involved. The expression of cell surface FasL was upregulated by stimulation with EGF and increased further by V-ATPase inhibitors. Moreover, EGF inhibited cytotoxic Fas antibody-induced apoptosis, whereas V-ATPase inhibitors disrupted the protective effect of EGF on apoptosis in A431 cells. Taken together, these results suggested that V-ATPase inhibitors induced EGF-dependent apoptosis in A431 cells, possibly through both the enhancement of EGF-induced cell surface expression of FasL and the disruption of an EGF-induced survival signal.
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Affiliation(s)
- Yuya Yoshimoto
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
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27
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Strachan GD, Rallapalli R, Pucci B, Lafond TP, Hall DJ. A transcriptionally inactive E2F-1 targets the MDM family of proteins for proteolytic degradation. J Biol Chem 2001; 276:45677-85. [PMID: 11568180 DOI: 10.1074/jbc.m103765200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
E2F-1-activated transcription promotes cell cycle progression and apoptosis. These functions are regulated by several factors including the E2F-1-binding protein MDM2 and the retinoblastoma protein pRb. Using a yeast two-hybrid screen we have identified the MDM2-related protein, MDMX, as an E2F-1-binding protein. In these studies we find that coexpression of MDMX with E2F-1 results in degradation of the MDMX protein. Although this proteolytic degradation can be blocked by the protease inhibitors bafilomycin A(1), N-acetyl-Leu-Leu-Norleu-AL, and N-acetyl-Leu-Leu-Met-AL, MDMX degradation is not inhibited by lactacystin, suggesting that degradation occurs by a proteasome-independent mechanism. Using an E2F-1 deletion mutant (E2F-1(180-437)) we show that E2F-1-targeted degradation of MDMX does not require the E2F-1 DNA binding domain and therefore is independent of E2F-1-driven transcription. We also find that this transcriptionally inactive E2F-1 mutant is capable of degrading the MDMX-related protein MDM2 and the MDMX isoform MDMX-S. Mapping of the E2F-1 C terminus reveals that neither a previously characterized C-terminal MDM2 binding domain nor the pRb binding domain on E2F-1 is required for MDMX and MDM2 degradation.
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Affiliation(s)
- G D Strachan
- Department of Orthopedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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28
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Gibson GA, Hill WG, Weisz OA. Evidence against the acidification hypothesis in cystic fibrosis. Am J Physiol Cell Physiol 2000; 279:C1088-99. [PMID: 11003589 DOI: 10.1152/ajpcell.2000.279.4.c1088] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The pleiotropic effects of cystic fibrosis (CF) result from the mislocalization or inactivity of an apical membrane chloride channel, the cystic fibrosis transmembrane conductance regulator (CFTR). CFTR may also modulate intracellular chloride conductances and thus affect organelle pH. To test the role of CFTR in organelle pH regulation, we developed a model system to selectively perturb the pH of a subset of acidified compartments in polarized cells and determined the effects on various protein trafficking steps. We then tested whether these effects were observed in cells lacking wild-type CFTR and whether reintroduction of CFTR affected trafficking in these cells. Our model system involves adenovirus-mediated expression of the influenza virus M2 protein, an acid-activated ion channel. M2 expression selectively slows traffic through the trans-Golgi network (TGN) and apical endocytic compartments in polarized Madin-Darby canine kidney (MDCK) cells. Expression of M2 or treatment with other pH perturbants also slowed protein traffic in the CF cell line CFPAC, suggesting that the TGN in this cell line is normally acidified. Expression of functional CFTR had no effect on traffic and failed to rescue the effect of M2. Our results argue against a role for CFTR in the regulation of organelle pH and protein trafficking in epithelial cells.
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Affiliation(s)
- G A Gibson
- Laboratory of Epithelial Cell Biology, Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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29
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Maquoi E, Frankenne F, Baramova E, Munaut C, Sounni NE, Remacle A, Noël A, Murphy G, Foidart JM. Membrane type 1 matrix metalloproteinase-associated degradation of tissue inhibitor of metalloproteinase 2 in human tumor cell lines. J Biol Chem 2000; 275:11368-78. [PMID: 10753951 DOI: 10.1074/jbc.275.15.11368] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Tissue inhibitor of metalloproteinase 2 (TIMP-2) is required for the membrane type 1 matrix metalloproteinase (MT1-MMP)-dependent activation of pro-MMP-2 on the cell surface. MT1-MMP-bound TIMP-2 has been shown to function as a receptor for secreted pro-MMP-2, resulting in the formation of a trimolecular complex. In the presence of uncomplexed active MT1-MMP, the prodomain of cell surface-associated MMP-2 is cleaved, and activated MMP-2 is released. However, the behavior of MT1-MMP-bound TIMP-2 during MMP-2 activation is currently unknown. In this study, (125)I-labeled recombinant TIMP-2 ((125)I-rTIMP-2) was used to investigate the fate of TIMP-2 during pro-MMP-2 activation by HT1080 and transfected A2058 cells. HT1080 and A2058 cells transfected with MT1-MMP cDNA (but not vector-transfected A2058 cells) were able to bind (125)I-rTIMP-2, to activate pro-MMP-2, and to process MT1-MMP into an inactive 43-kDa form. Under these conditions, (125)I-rTIMP-2 bound to the cell surface was rapidly internalized and degraded in intracellular organelles through a bafilomycin A(1)-sensitive mechanism, and (125)I-bearing low molecular mass fragment(s) were released in the culture medium. These different processes were inhibited by hydroxamic acid-based synthetic MMP inhibitors and rTIMP-2, but not by rTIMP-1 or cysteine, serine, or aspartic proteinase inhibitors. These results support the concept that the MT1-MMP-dependent internalization and degradation of TIMP-2 by some tumor cells might be involved in the regulation of pericellular proteolysis.
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Affiliation(s)
- E Maquoi
- Laboratory of Tumor and Development Biology, University of Liège, Tour de Pathologie (B23), Sart Tilman, B-4000 Liège, Belgium
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30
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Henkel JR, Popovich JL, Gibson GA, Watkins SC, Weisz OA. Selective perturbation of early endosome and/or trans-Golgi network pH but not lysosome pH by dose-dependent expression of influenza M2 protein. J Biol Chem 1999; 274:9854-60. [PMID: 10092677 DOI: 10.1074/jbc.274.14.9854] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Many sorting stations along the biosynthetic and endocytic pathways are acidified, suggesting a role for pH regulation in protein traffic. However, the function of acidification in individual compartments has been difficult to examine because global pH perturbants affect all acidified organelles in the cell and also have numerous side effects. To circumvent this problem, we have developed a method to selectively perturb the pH of a subset of acidified compartments. We infected HeLa cells with a recombinant adenovirus encoding influenza virus M2 protein (an acid-activated ion channel that dissipates proton gradients across membranes) and measured the effects on various steps in protein transport. At low multiplicity of infection (m.o.i.), delivery of influenza hemagglutinin from the trans-Golgi network to the cell surface was blocked, but there was almost no effect on the rate of recycling of internalized transferrin. At higher m.o.i., transferrin recycling was inhibited, suggesting increased accumulation of M2 in endosomes. Interestingly, even at the higher m.o.i., M2 expression had no effect on lysosome morphology or on EGF degradation, suggesting that lysosomal pH was not compromised by M2 expression. However, delivery of newly synthesized cathepsin D to lysosomes was slowed in cells expressing active M2, suggesting that acidification of the TGN and endosomes is important for efficient delivery of lysosomal hydrolases. Fluorescence labeling using a pH-sensitive dye confirmed the reversible effect of M2 on the pH of a subset of acidified compartments in the cell. The ability to dissect the role of acidification in individual steps of a complex pathway should be useful for numerous other studies on protein processing and transport.
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Affiliation(s)
- J R Henkel
- Laboratory of Epithelial Cell Biology, Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
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31
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Abstract
Megalomicin (MGM) is a macrolide antibiotic which has been demonstrated previously to cause an anomalous glycosylation of viral proteins. Here we show that MGM produces profound alterations on Golgi morphology and function. The addition of MGM at 50 microM for 1 h caused a dilation of the Golgi detected by immunofluorescence staining for medial- and trans-Golgi markers. The effect of MGM was clearly more intense on the trans-side of the Golgi, as evidenced in electron microscope preparations. The effect on Golgi morphology was reversible and correlated with an impairment of glycoprotein processing in the trans-Golgi. Thus, although the vesicular stomatitis virus G protein was processed in the presence of MGM to an endoglycosidase H-resistant form, it was poorly sialylated. The sialylation of cellular proteins was also inhibited, resulting in cells with low level of sialylation on the cell surface. However MGM did not inhibit the activities of the galactosyl- or sialyltransferase as measured in vitro. MGM inhibited cis- to medial-, and more strongly, medial- to trans-Golgi transport of vesicular stomatitis virus G protein in an in vitro system, suggesting that the impairment in glycoprotein maturation observed in vivo is the result of intra-Golgi transport inhibition.
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Affiliation(s)
- P Bonay
- Centro de Biologi;a Molecular Severo Ochoa, Consejo Superior de Investigaciones Cienti;ficas-Universidad Autónoma de Madrid, Madrid 28049, Spain
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32
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Tapper H, Sundler R. Bafilomycin A1 inhibits lysosomal, phagosomal, and plasma membrane H(+)-ATPase and induces lysosomal enzyme secretion in macrophages. J Cell Physiol 1995; 163:137-44. [PMID: 7896890 DOI: 10.1002/jcp.1041630116] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Bafilomycin A1, a specific inhibitor of H(+)-ATPases of the vacuolar type, was in the present study shown, at similar concentrations, to induce secretion of lysosomal enzyme and to elevate lysosomal pH in mouse macrophages. These results lend support to the previous suggestion of a triggering role for an increase in lysosomal pH and a permissive role for cytosolic pH in the exocytosis of macrophage lysosomal enzyme. Vacuolar H(+)-ATPases are present in the macrophage plasma membrane as well as in intracellular membranes, for example, those of the lysosomal and phagosomal compartments. Phagosomal acidification was shown to be achieved in part by a mechanism with a similar sensitivity to bafilomycin A1 as lysosomal H+ transport and in part by an early, bafilomycin A1-insensitive mechanism. We found a lesser sensitivity towards bafilomycin A1 of the lysosomal and phagosomal H(+)-ATPase than that localized in the plasma membrane, indicating differences among H(+)-ATPases at the subcellular level. Also, by attempts to mobilize lysosomal H(+)-ATPase to the plasma membrane, support was obtained for the notion that subcellular H(+)-ATPase populations differ and thus possibly could be differentially regulated.
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Affiliation(s)
- H Tapper
- Department of Medical and Physiological Chemistry, Lund University, Sweden
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33
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Knops J, Suomensaari S, Lee M, McConlogue L, Seubert P, Sinha S. Cell-type and amyloid precursor protein-type specific inhibition of A beta release by bafilomycin A1, a selective inhibitor of vacuolar ATPases. J Biol Chem 1995; 270:2419-22. [PMID: 7852298 DOI: 10.1074/jbc.270.6.2419] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Treatment of human 293 cells transfected with amyloid precursor protein (APP)K595N,M596L (the "Swedish" mutation) with a specific inhibitor of the vacuolar H(+)-ATPases, bafilomycin A1 (baf A), leads to a potent inhibition of the release of the A beta peptide. This is accompanied by a selective inhibition of beta-secretase activity. Surprisingly, baf A did not inhibit the production of A beta from either wild-type APP (WT APP) or from APPv7171 (the "Hardy" mutation), expressed in the same cell type. In contrast, the robust production of A beta from a human neuroglioma-derived cell line (HS683) transfected with WT APP, or from primary human mixed brain cultures (HMBC) expressing genomic WT APP, were also effectively inhibited by baf A. The inhibition of A beta production from the HMBC was also accompanied by the inhibition of beta-s-APP release. No inhibition of alpha-s-APP release was seen in any of the cell types tested. These results indicate that intracellular acidic processes are rate-limiting for beta-secretase cleavage and A beta production from SW APP, but not WT APP, in the peripheral 293 cell line. Furthermore, such acidic processes also play a rate-limiting role in A beta release from human central nervous system-derived cells, including HMBC. Differential trafficking of the SW APP into an acidic compartment conducive to beta-secretase cleavage and A beta release could be one explanation for the increased production of A beta observed on expression of this mutation.
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Affiliation(s)
- J Knops
- Athena Neurosciences, Inc., South San Francisco, California 94080
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34
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Isidoro C, Demoz M, De Stefanis D, Mainferme F, Wattiaux R, Baccino FM. Altered intracellular processing and enhanced secretion of procathepsin D in a highly deviated rat hepatoma. Int J Cancer 1995; 60:61-4. [PMID: 7814153 DOI: 10.1002/ijc.2910600109] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Both freshly-isolated rat hepatocytes and Morris hepatoma 7777 cells synthesized cathepsin D as a precursor that was either processed intracellular to smaller mature forms or secreted into the medium. The pattern of mature enzyme forms was different in the 2 cell types. In addition, the relative amount of precursor secreted was much higher for hepatoma cells. Monensin strongly enhanced the secretion and also impaired the intracellular transport-linked maturation of procathepsin D in hepatocytes, while it markedly inhibited intracellular maturation and only slightly increased secretion of the pro-enzyme in hepatoma cells. Ammonium chloride influenced the intralysosomal segregation and maturation of procathepsin D in hepatocytes but not in hepatoma cells. Our observations indicate that (i) the lysosomal segregation of cathepsin D was less efficient and its fractional secretion higher in hepatoma cells than in hepatocytes; (ii) in the 2 cell types, delivery to lysosomes and processing of procathepsin D were differently sensitive to increases in the vacuolar pH.
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Affiliation(s)
- C Isidoro
- Dipartimento di Medicina ed Oncologia Sperimentale, Università di Torino, Italy
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35
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Active vacuolar H+ATPase is required for both endocytic and exocytic processes during viral infection of BHK-21 cells. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32480-8] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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