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Luu AZ, Chowdhury B, Al-Omran M, Teoh H, Hess DA, Verma S. Role of Endothelium in Doxorubicin-Induced Cardiomyopathy. JACC Basic Transl Sci 2018; 3:861-870. [PMID: 30623145 PMCID: PMC6314956 DOI: 10.1016/j.jacbts.2018.06.005] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 06/19/2018] [Indexed: 12/29/2022]
Abstract
The clinical use of doxorubicin in cancer is limited by cardiotoxic effects that can lead to heart failure. Whereas earlier work focused on the direct impact of doxorubicin on cardiomyocytes, recent studies have turned to the endothelium, because doxorubicin-damaged endothelial cells can trigger the development and progression of cardiomyopathy by decreasing the release and activity of key endothelial factors and inducing endothelial cell death. Thus, the endothelium represents a novel target for improving the detection, management, and prevention of doxorubicin-induced cardiomyopathy.
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Key Words
- AKT, protein kinase B
- Bcl-2, B-cell lymphoma-2
- DNA, deoxyribonucleic acid
- ERK1/2, extracellular signal-regulated kinase 1/2
- ET, endothelin
- LV, left ventricular
- MRP, multidrug resistance protein
- NADPH, nicotinamide adenine dinucleotide phosphate
- NO, nitric oxide
- NOS, nitric oxide synthase
- NRG-1, neuregulin-1
- PGI2, prostaglandin I2
- PI3K, phosphoinositide 3-kinase
- RNS, reactive nitrogen species
- ROS, reactive oxygen species
- ZO, zona occludens
- cardiomyopathy
- doxorubicin
- endothelium
- heart failure
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Affiliation(s)
- Albert Z Luu
- Division of Cardiac Surgery, Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.,Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Biswajit Chowdhury
- Division of Cardiac Surgery, Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada
| | - Mohammed Al-Omran
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada.,Division of Vascular Surgery, Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.,Department of Surgery, University of Toronto, Toronto, Ontario, Canada.,Department of Surgery, King Saud University, Riyadh, Kingdom of Saudi Arabia
| | - Hwee Teoh
- Division of Cardiac Surgery, Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.,Division of Endocrinology and Metabolism, Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada
| | - David A Hess
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada.,Division of Vascular Surgery, Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.,Molecular Medicine Research Laboratories, Krembil Centre for Stem Cell Biology, Robarts Research Institute, London, Ontario, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Subodh Verma
- Division of Cardiac Surgery, Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.,Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada.,Department of Surgery, University of Toronto, Toronto, Ontario, Canada
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Doh JH, Lutz S, Curcio MJ. Co-translational localization of an LTR-retrotransposon RNA to the endoplasmic reticulum nucleates virus-like particle assembly sites. PLoS Genet 2014; 10:e1004219. [PMID: 24603646 PMCID: PMC3945221 DOI: 10.1371/journal.pgen.1004219] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 01/18/2014] [Indexed: 11/18/2022] Open
Abstract
The transcript of retrovirus-like transposons functions as an mRNA for synthesis of capsid and replication proteins and as the genomic RNA of virus-like particles (VLPs), wherein the genome is replicated. Retrotransposon RNA and proteins coalesce in a cytoplasmic focus, or retrosome, to initiate VLP assembly, but it is not known how the retrosome is nucleated. We determined how the RNA and Gag protein of the Saccharomyces cerevisiae Ty1 retrotransposon are directed to the retrosome. We found that Ty1 RNA is translated in association with signal recognition particle (SRP), a universally conserved chaperone that binds specific ribosome-nascent chain (RNC) complexes and targets the nascent peptide to the endoplasmic reticulum (ER). Gag is translocated to the ER lumen; yet, it is also found in the cytoplasm, associated with SRP-RNC complexes. In the absence of ER translocation, Gag is synthesized but rapidly degraded, and Ty1 RNA does not coalesce in retrosomes. These findings suggest that Gag adopts a stable conformation in the ER lumen, is retrotranslocated to the cytoplasm, binds to Ty1 RNA on SRP-RNC complexes and multimerizes to nucleate retrosomes. Consistent with this model, we show that slowing the rate of co-translational ER translocation by limiting SRP increases the prevalence of retrosomes, while suppressing the translocation defect of srp hypomorphs by slowing translational elongation rapidly decreases retrosome formation. Thus, retrosomes are dynamic foci of Ty1 RNA-RNC complexes whose formation is modulated by the rate of co-translational ER translocation. Together, these findings suggest that translating Ty1 mRNA and the genomic RNA of VLPs originate in a single pool and moreover, that co-translational localization of Ty1 RNA nucleates the presumptive VLP assembly site. The separation of nascent Gag from its RNA template by transit through the ER allows Gag to bind translating Ty1 RNA without displaying a cis-preference for its encoding RNA. Retrotransposons are mobile elements that have invaded the genomes of organisms from bacteria to humans. Facilitated by host co-factors, retrotransposon proteins copy their RNA genomes into DNA that integrates into the host genome, causing mutations and genome instability. The yeast Ty1 element belongs to a family of retrotransposons that are related to infectious retroviruses. Ty1 RNA and its coat protein, Gag, assemble into virus-like particles, wherein the RNA is copied into DNA. It was not previously known how Ty1 RNA and Gag are concentrated in a specific cellular location to initiate the assembly of virus-like particles. In this study, we show that Ty1 RNA is brought to the presumptive assembly site during translation by the protein chaperone, signal recognition particle. As Ty1 RNA is translated, the nascent Gag polypeptide enters the lumen of the endoplasmic reticulum, where Gag adopts a stable conformation before returning to the cytoplasm to bind to translating Ty1 RNA. An interaction between Gag molecules bound to translating Ty1 RNA results in the nucleation of the virus-like particle assembly site. Our findings identify new host co-factors in retrotransposon mobility and suggest potential approaches to controlling retrotransposon-associated genome instability in aging and cancer.
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Affiliation(s)
- Jung H. Doh
- Laboratory of Molecular Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Sheila Lutz
- Laboratory of Molecular Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - M. Joan Curcio
- Laboratory of Molecular Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, New York, United States of America
- * E-mail:
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Hrabe T, Chen Y, Pfeffer S, Cuellar LK, Mangold AV, Förster F. PyTom: a python-based toolbox for localization of macromolecules in cryo-electron tomograms and subtomogram analysis. J Struct Biol 2011; 178:177-88. [PMID: 22193517 DOI: 10.1016/j.jsb.2011.12.003] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 11/25/2011] [Accepted: 12/05/2011] [Indexed: 10/14/2022]
Abstract
Cryo-electron tomography (CET) is a three-dimensional imaging technique for structural studies of macromolecules under close-to-native conditions. In-depth analysis of macromolecule populations depicted in tomograms requires identification of subtomograms corresponding to putative particles, averaging of subtomograms to enhance their signal, and classification to capture the structural variations among them. Here, we introduce the open-source platform PyTom that unifies standard tomogram processing steps in a python toolbox. For subtomogram averaging, we implemented an adaptive adjustment of scoring and sampling that clearly improves the resolution of averages compared to static strategies. Furthermore, we present a novel stochastic classification method that yields significantly more accurate classification results than two deterministic approaches in simulations. We demonstrate that the PyTom workflow yields faithful results for alignment and classification of simulated and experimental subtomograms of ribosomes and GroEL(14)/GroEL(14)GroES(7), respectively, as well as for the analysis of ribosomal 60S subunits in yeast cell lysate. PyTom enables parallelized processing of large numbers of tomograms, but also provides a convenient, sustainable environment for algorithmic development.
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Affiliation(s)
- Thomas Hrabe
- Max-Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
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Nepliouev I, Zhang ZS, Stiber JA. Effect of oxidative stress on homer scaffolding proteins. PLoS One 2011; 6:e26128. [PMID: 22043307 PMCID: PMC3197146 DOI: 10.1371/journal.pone.0026128] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Accepted: 09/20/2011] [Indexed: 01/29/2023] Open
Abstract
Homer proteins are a family of multifaceted scaffolding proteins that participate in the organization of signaling complexes at the post-synaptic density and in a variety of tissues including striated muscle. Homer isoforms form multimers via their C-terminal coiled coil domains, which allows for the formation of a polymeric network in combination with other scaffolding proteins. We hypothesized that the ability of Homer isoforms to serve as scaffolds would be influenced by oxidative stress. We have found by standard SDS-PAGE of lysates from adult mouse skeletal muscle exposed to air oxidation that Homer migrates as both a dimer and monomer in the absence of reducing agents and solely as a monomer in the presence of a reducing agent, suggesting that Homer dimers exposed to oxidation could be modified by the presence of an inter-molecular disulfide bond. Analysis of the peptide sequence of Homer 1b revealed the presence of only two cysteine residues located adjacent to the C-terminal coiled-coil domain. HEK 293 cells were transfected with wild-type and cysteine mutant forms of Homer 1b and exposed to oxidative stress by addition of menadione, which resulted in the formation of disulfide bonds except in the double mutant (C246G, C365G). Exposure of myofibers from adult mice to oxidative stress resulted in decreased solubility of endogenous Homer isoforms. This change in solubility was dependent on disulfide bond formation. In vitro binding assays revealed that cross-linking of Homer dimers enhanced the ability of Homer 1b to bind Drebrin, a known interacting partner. Our results show that oxidative stress results in disulfide cross-linking of Homer isoforms and loss of solubility of Homer scaffolds. This suggests that disulfide cross-linking of a Homer polymeric network may contribute to the pathophysiology seen in neurodegenerative diseases and myopathies characterized by oxidative stress.
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Affiliation(s)
- Igor Nepliouev
- Ion Channel Research Unit and Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Zhu-Shan Zhang
- Ion Channel Research Unit and Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Jonathan A. Stiber
- Ion Channel Research Unit and Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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