The Experts below are selected from a list of 5238 Experts worldwide ranked by ideXlab platform
Steven C. Borkan - One of the best experts on this subject based on the ideXlab platform.
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Cross organelle stress response disruption promotes gentamicin-induced Proteotoxicity
Cell Death & Disease, 2020Co-Authors: Chinaemere Igwebuike, Julia Yaglom, Leah Huiting, Hui Feng, Joshua D. Campbell, Zhiyong Wang, Andrea Havasi, David Pimentel, Michael Y. Sherman, Steven C. BorkanAbstract:Gentamicin is a nephrotoxic antibiotic that causes acute kidney injury (AKI) primarily by targeting the proximal tubule epithelial cell. The development of an effective therapy for gentamicin-induced renal cell injury is limited by incomplete mechanistic insight. To address this challenge, we propose that RNAi signal pathway screening could identify a unifying mechanism of gentamicin-induced cell injury and suggest a therapeutic strategy to ameliorate it. Computational analysis of RNAi signal screens in gentamicin-exposed human proximal tubule cells suggested the cross-organelle stress response (CORE), the unfolded protein response (UPR), and cell chaperones as key targets of gentamicin-induced injury. To test this hypothesis, we assessed the effect of gentamicin on the CORE, UPR, and cell chaperone function, and tested the therapeutic efficacy of enhancing cell chaperone content. Early gentamicin exposure disrupted the CORE, evidenced by a rise in the ATP:ADP ratio, mitochondrial-specific H_2O_2 accumulation, Drp-1-mediated mitochondrial fragmentation, and endoplasmic reticulum–mitochondrial dissociation. CORE disruption preceded measurable increases in whole-cell oxidative stress, misfolded protein content, transcriptional UPR activation, and its untoward downstream effects: CHOP expression, PARP cleavage, and cell death. Geranylgeranylacetone, a therapeutic that increases cell chaperone content, prevented mitochondrial H_2O_2 accumulation, preserved the CORE, reduced the burden of misfolded proteins and CHOP expression, and significantly improved survival in gentamicin-exposed cells. We identify CORE disruption as an early and remediable cause of gentamicin Proteotoxicity that precedes downstream UPR activation and cell death. Preserving the CORE significantly improves renal cell survival likely by reducing organelle-specific Proteotoxicity during gentamicin exposure.
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Cross organelle stress response disruption promotes gentamicin-induced Proteotoxicity.
Cell Death & Disease, 2020Co-Authors: Chinaemere Igwebuike, Julia Yaglom, Leah Huiting, Hui Feng, Joshua D. Campbell, Zhiyong Wang, Andrea Havasi, Michael Y. Sherman, David R. Pimentel, Steven C. BorkanAbstract:Gentamicin is a nephrotoxic antibiotic that causes acute kidney injury (AKI) primarily by targeting the proximal tubule epithelial cell. The development of an effective therapy for gentamicin-induced renal cell injury is limited by incomplete mechanistic insight. To address this challenge, we propose that RNAi signal pathway screening could identify a unifying mechanism of gentamicin-induced cell injury and suggest a therapeutic strategy to ameliorate it. Computational analysis of RNAi signal screens in gentamicin-exposed human proximal tubule cells suggested the cross-organelle stress response (CORE), the unfolded protein response (UPR), and cell chaperones as key targets of gentamicin-induced injury. To test this hypothesis, we assessed the effect of gentamicin on the CORE, UPR, and cell chaperone function, and tested the therapeutic efficacy of enhancing cell chaperone content. Early gentamicin exposure disrupted the CORE, evidenced by a rise in the ATP:ADP ratio, mitochondrial-specific H2O2 accumulation, Drp-1-mediated mitochondrial fragmentation, and endoplasmic reticulum-mitochondrial dissociation. CORE disruption preceded measurable increases in whole-cell oxidative stress, misfolded protein content, transcriptional UPR activation, and its untoward downstream effects: CHOP expression, PARP cleavage, and cell death. Geranylgeranylacetone, a therapeutic that increases cell chaperone content, prevented mitochondrial H2O2 accumulation, preserved the CORE, reduced the burden of misfolded proteins and CHOP expression, and significantly improved survival in gentamicin-exposed cells. We identify CORE disruption as an early and remediable cause of gentamicin Proteotoxicity that precedes downstream UPR activation and cell death. Preserving the CORE significantly improves renal cell survival likely by reducing organelle-specific Proteotoxicity during gentamicin exposure.
Jianxing Song - One of the best experts on this subject based on the ideXlab platform.
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Environment-transformable sequence–structure relationship: a general mechanism for Proteotoxicity
Biophysical Reviews, 2017Co-Authors: Jianxing SongAbstract:In his Nobel Lecture, Anfinsen stated “the native conformation is determined by the totality of interatomic interactions and hence by the amino acid sequence, in a given environment.” As aqueous solutions and membrane systems co-exist in cells, proteins are classified into membrane and non-membrane proteins, but whether one can transform one into the other remains unknown. Intriguingly, many well-folded non-membrane proteins are converted into “insoluble” and toxic forms by aging- or disease-associated factors, but the underlying mechanisms remain elusive. In 2005, we discovered a previously unknown regime of proteins seemingly inconsistent with the classic “Salting-in” dogma: “insoluble” proteins including the integral membrane fragments could be solubilized in the ion-minimized water. We have thus successfully studied “insoluble” forms of ALS-causing P56S-MSP, L126Z-SOD1, nascent SOD1 and C71G-Profilin1, as well as E. coli S1 fragments. The results revealed that these “insoluble” forms are either unfolded or co-exist with their unfolded states. Most unexpectedly, these unfolded states acquire a novel capacity of interacting with membranes energetically driven by the formation of helices/loops over amphiphilic/hydrophobic regions which universally exit in proteins but are normally locked away in their folded native states. Our studies suggest that most, if not all, proteins contain segments which have the dual ability to fold into distinctive structures in aqueous and membrane environments. The abnormal membrane interaction might initiate disease and/or aging processes; and its further coupling with protein aggregation could result in radical Proteotoxicity by forming inclusions composed of damaged membranous organelles and protein aggregates. Therefore, environment-transformable sequence–structure relationship may represent a general mechanism for Proteotoxicity.
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Environment-transformable sequence-structure relationship: a general mechanism for Proteotoxicity.
Biophysical Reviews, 2017Co-Authors: Jianxing SongAbstract:In his Nobel Lecture, Anfinsen stated “the native conformation is determined by the totality of interatomic interactions and hence by the amino acid sequence, in a given environment.” As aqueous solutions and membrane systems co-exist in cells, proteins are classified into membrane and non-membrane proteins, but whether one can transform one into the other remains unknown. Intriguingly, many well-folded non-membrane proteins are converted into “insoluble” and toxic forms by aging- or disease-associated factors, but the underlying mechanisms remain elusive. In 2005, we discovered a previously unknown regime of proteins seemingly inconsistent with the classic “Salting-in” dogma: “insoluble” proteins including the integral membrane fragments could be solubilized in the ion-minimized water. We have thus successfully studied “insoluble” forms of ALS-causing P56S-MSP, L126Z-SOD1, nascent SOD1 and C71G-Profilin1, as well as E. coli S1 fragments. The results revealed that these “insoluble” forms are either unfolded or co-exist with their unfolded states. Most unexpectedly, these unfolded states acquire a novel capacity of interacting with membranes energetically driven by the formation of helices/loops over amphiphilic/hydrophobic regions which universally exit in proteins but are normally locked away in their folded native states. Our studies suggest that most, if not all, proteins contain segments which have the dual ability to fold into distinctive structures in aqueous and membrane environments. The abnormal membrane interaction might initiate disease and/or aging processes; and its further coupling with protein aggregation could result in radical Proteotoxicity by forming inclusions composed of damaged membranous organelles and protein aggregates. Therefore, environment-transformable sequence–structure relationship may represent a general mechanism for Proteotoxicity.
Xuejun Wang - One of the best experts on this subject based on the ideXlab platform.
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Priming the Proteasome to Protect against Proteotoxicity
Trends in Molecular Medicine, 2020Co-Authors: Xuejun Wang, Hongmin WangAbstract:Increased proteotoxic stress (IPTS) resulting from the increased production or decreased removal of abnormally folded proteins is recognized as an important pathogenic factor for a large group of highly disabling and life-threatening human diseases, such as neurodegenerative disorders and many heart diseases. The proteasome is pivotal to the timely removal of abnormal proteins but its functional capacity often becomes inadequate in the disease conditions; consequently, proteasome functional insufficiency in return exacerbates IPTS. Recent research in proteasome biology reveals that the proteasome can be activated by endogenous protein kinases, making it possible to pharmacologically prime the proteasome for treating diseases with IPTS.
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tfeb activation protects against cardiac Proteotoxicity via increasing autophagic flux
Journal of Molecular and Cellular Cardiology, 2017Co-Authors: Hanming Zhang, Xuejun WangAbstract:Abstract Insufficient lysosomal removal of autophagic cargoes in cardiomyocytes has been suggested as a main cause for the impairment of the autophagic-lysosomal pathway (ALP) in many forms of heart disease including cardiac proteinopathy and may play an important pathogenic role; however, the molecular basis and the correcting strategy for the cardiac ALP insufficiency require further investigation. The present study was sought to determine whether myocardial expression and activity of TFEB, the recently identified ALP master regulator, are impaired in a cardiac proteinopathy mouse model and to determine the effect of genetic manipulation of TFEB expression on autophagy and Proteotoxicity in a cardiomyocyte model of proteinopathy. We found that increased myocardial TFEB mRNA levels and a TFEB protein isoform switch were associated with marked decreases in the mRNA levels of representative TFEB target genes and increased mTORC1 activation, in mice with cardiac transgenic expression of a missense (R120G) mutant αB-crystallin (CryAB R120G ), a well-established model of cardiac proteinopathy. Using neonatal rat ventricular cardiomyocyte cultures, we demonstrated that downregulation of TFEB decreased autophagic flux in cardiomyocytes both at baseline and during CryAB R120G overexpression and increased CryAB R120G protein aggregates. Conversely, forced TFEB overexpression increased autophagic flux and remarkably attenuated the CryABR 120G overexpression-induced accumulation of ubiquitinated proteins, caspase 3 cleavage, LDH leakage, and decreases in cell viability. Moreover, these protective effects of TFEB were dramatically diminished by inhibiting autophagy. We conclude that myocardial TFEB signaling is impaired in cardiac proteinopathy and forced TFEB overexpression protects against Proteotoxicity in cardiomyocytes through improving ALP activity.
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tfeb activation protects against cardiac Proteotoxicity via increasing autophagic flux
Journal of Molecular and Cellular Cardiology, 2017Co-Authors: Hanming Zhang, Xuejun WangAbstract:Abstract Insufficient lysosomal removal of autophagic cargoes in cardiomyocytes has been suggested as a main cause for the impairment of the autophagic-lysosomal pathway (ALP) in many forms of heart disease including cardiac proteinopathy and may play an important pathogenic role; however, the molecular basis and the correcting strategy for the cardiac ALP insufficiency require further investigation. The present study was sought to determine whether myocardial expression and activity of TFEB, the recently identified ALP master regulator, are impaired in a cardiac proteinopathy mouse model and to determine the effect of genetic manipulation of TFEB expression on autophagy and Proteotoxicity in a cardiomyocyte model of proteinopathy. We found that increased myocardial TFEB mRNA levels and a TFEB protein isoform switch were associated with marked decreases in the mRNA levels of representative TFEB target genes and increased mTORC1 activation, in mice with cardiac transgenic expression of a missense (R120G) mutant αB-crystallin (CryAB R120G ), a well-established model of cardiac proteinopathy. Using neonatal rat ventricular cardiomyocyte cultures, we demonstrated that downregulation of TFEB decreased autophagic flux in cardiomyocytes both at baseline and during CryAB R120G overexpression and increased CryAB R120G protein aggregates. Conversely, forced TFEB overexpression increased autophagic flux and remarkably attenuated the CryABR 120G overexpression-induced accumulation of ubiquitinated proteins, caspase 3 cleavage, LDH leakage, and decreases in cell viability. Moreover, these protective effects of TFEB were dramatically diminished by inhibiting autophagy. We conclude that myocardial TFEB signaling is impaired in cardiac proteinopathy and forced TFEB overexpression protects against Proteotoxicity in cardiomyocytes through improving ALP activity.
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the interplay between autophagy and the ubiquitin proteasome system in cardiac Proteotoxicity
Biochimica et Biophysica Acta, 2015Co-Authors: Changhua Wang, Xuejun WangAbstract:Abstract Proteotoxicity refers to the detrimental effects of damaged/misfolded proteins on the cell. Cardiac muscle is particularly susceptible to Proteotoxicity because sustained and severe proteotoxic stress leads to cell death and the cardiac muscle has very limited self-renewal capacity. The ubiquitin–proteasome system (UPS) and the autophagic-lysosomal pathway (ALP) are two major pathways responsible for degradation of most cellular proteins. Alterations of UPS and ALP functions are associated with the accumulation of proteotoxic species in the heart, a key pathological feature of common forms of heart disease including idiopathic, ischemic, and pressure-overloaded cardiomyopathies and a large subset of congestive heart failure. Emerging evidence suggests that proteasome inhibition or impairment activates autophagy and conversely, acute ALP inhibition may sometimes increase intrinsic proteasome peptidase activities but chronic ALP inhibition hinders UPS performance in ubiquitinated protein degradation. The exact molecular basis on which the two degradative pathways interact remains largely undefined. Here we review current understanding of the roles of the UPS and autophagy in the control of cardiac Proteotoxicity, with a specific focus on the crosstalk between the two pathways. This article is part of a Special Issue entitled: Autophagy and protein quality control in cardiometabolic diseases.
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The interplay between autophagy and the ubiquitin–proteasome system in cardiac Proteotoxicity
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, 2015Co-Authors: Changhua Wang, Xuejun WangAbstract:Abstract Proteotoxicity refers to the detrimental effects of damaged/misfolded proteins on the cell. Cardiac muscle is particularly susceptible to Proteotoxicity because sustained and severe proteotoxic stress leads to cell death and the cardiac muscle has very limited self-renewal capacity. The ubiquitin–proteasome system (UPS) and the autophagic-lysosomal pathway (ALP) are two major pathways responsible for degradation of most cellular proteins. Alterations of UPS and ALP functions are associated with the accumulation of proteotoxic species in the heart, a key pathological feature of common forms of heart disease including idiopathic, ischemic, and pressure-overloaded cardiomyopathies and a large subset of congestive heart failure. Emerging evidence suggests that proteasome inhibition or impairment activates autophagy and conversely, acute ALP inhibition may sometimes increase intrinsic proteasome peptidase activities but chronic ALP inhibition hinders UPS performance in ubiquitinated protein degradation. The exact molecular basis on which the two degradative pathways interact remains largely undefined. Here we review current understanding of the roles of the UPS and autophagy in the control of cardiac Proteotoxicity, with a specific focus on the crosstalk between the two pathways. This article is part of a Special Issue entitled: Autophagy and protein quality control in cardiometabolic diseases.
Federica Del Monte - One of the best experts on this subject based on the ideXlab platform.
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corrigendum pre amyloid oligomers budding a metastatic mechanism of Proteotoxicity
Scientific Reports, 2017Co-Authors: Fabrizio Bernini, Daniele Malferrari, Marcello Pignataro, Carlo Augusto Bortolotti, Giulia Di Rocco, Lidia Lancellotti, Maria Franca Brigatti, Rakez Kayed, Marco Borsari, Federica Del MonteAbstract:Scientific Reports 6: Article number: 35865; published online: 24 October 2016; updated: 19 January 2017. The Author Contributions statement in this Article is incomplete: F.B., D.M., M.P., L.L., F.d.M. and E.C. acquired and analyzed the data; C.A.B., G.D.R., M.F.B. and M.B. provided critical input to the analyzed data and to the manuscript; R.
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Pre-amyloid oligomers budding: A metastatic mechanism of Proteotoxicity
Scientific Reports, 2016Co-Authors: Fabrizio Bernini, Daniele Malferrari, Marcello Pignataro, Carlo Augusto Bortolotti, Giulia Di Rocco, Lidia Lancellotti, Maria Franca Brigatti, Rakez Kayed, Marco Borsari, Federica Del MonteAbstract:The pathological hallmark of misfolded protein diseases and aging is the accumulation of proteotoxic aggregates. However, the mechanisms of Proteotoxicity and the dynamic changes in fiber formation and dissemination remain unclear, preventing a cure. Here we adopted a reductionist approach and used atomic force microscopy to define the temporal and spatial changes of amyloid aggregates, their modes of dissemination and the biochemical changes that may influence their growth. We show that pre-amyloid oligomers (PAO) mature to form linear and circular protofibrils, and amyloid fibers, and those can break reforming PAO that can migrate invading neighbor structures. Simulating the effect of immunotherapy modifies the dynamics of PAO formation. Anti-fibers as well as anti-PAO antibodies fragment the amyloid fibers, however the fragmentation using anti-fibers antibodies favored the migration of PAO. In conclusion, we provide evidence for the mechanisms of misfolded protein maturation and propagation and the effects of interventions on the resolution and dissemination of amyloid pathology.
George M Church - One of the best experts on this subject based on the ideXlab platform.
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programmable transcriptional repression in mycobacteria using an orthogonal crispr interference platform
Nature microbiology, 2017Co-Authors: Jeremy M Rock, Forrest F Hopkins, Marieme Diallo, Elias R Gerrick, Justin R Pritchard, Michael R Chase, Alejandro Chavez, George M ChurchAbstract:The development of new drug regimens that allow rapid, sterilizing treatment of tuberculosis has been limited by the complexity and time required for genetic manipulations in Mycobacterium tuberculosis. CRISPR interference (CRISPRi) promises to be a robust, easily engineered and scalable platform for regulated gene silencing. However, in M. tuberculosis, the existing Streptococcus pyogenes Cas9-based CRISPRi system is of limited utility because of relatively poor knockdown efficiency and Proteotoxicity. To address these limitations, we screened eleven diverse Cas9 orthologues and identified four that are broadly functional for targeted gene knockdown in mycobacteria. The most efficacious of these proteins, the CRISPR1 Cas9 from Streptococcus thermophilus (dCas9Sth1), typically achieves 20- to 100-fold knockdown of endogenous gene expression with minimal Proteotoxicity. In contrast to other CRISPRi systems, dCas9Sth1-mediated gene knockdown is robust when targeted far from the transcriptional start site, thereby allowing high-resolution dissection of gene function in the context of bacterial operons. We demonstrate the utility of this system by addressing persistent controversies regarding drug synergies in the mycobacterial folate biosynthesis pathway. We anticipate that the dCas9Sth1 CRISPRi system will have broad utility for functional genomics, genetic interaction mapping and drug-target profiling in M. tuberculosis. Screening Cas9 orthologues to improve CRISPR interference in mycobacteria identified four that are broadly functional for targeted gene knockdown, one of which (dCas9Sth1) achieves a 20–100-fold knockdown of endogenous gene expression with minimal Proteotoxicity.
