151
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Smith SL, Pitt AR, Spickett CM. Approaches to Investigating the Protein Interactome of PTEN. J Proteome Res 2020; 20:60-77. [PMID: 33074689 DOI: 10.1021/acs.jproteome.0c00570] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The tumor suppressor phosphatase and tensin homologue (PTEN) is a redox-sensitive dual specificity phosphatase with an essential role in the negative regulation of the PI3K-AKT signaling pathway, affecting metabolic and cell survival processes. PTEN is commonly mutated in cancer, and dysregulation in the metabolism of PIP3 is implicated in other diseases such as diabetes. PTEN interactors are responsible for some functional roles of PTEN beyond the negative regulation of the PI3K pathway and are thus of great importance in cell biology. Both high-data content proteomics-based approaches and low-data content PPI approaches have been used to investigate the interactome of PTEN and elucidate further functions of PTEN. While low-data content approaches rely on co-immunoprecipitation and Western blotting, and as such require previously generated hypotheses, high-data content approaches such as affinity pull-down proteomic assays or the yeast 2-hybrid system are hypothesis generating. This review provides an overview of the PTEN interactome, including redox effects, and critically appraises the methods and results of high-data content investigations into the global interactome of PTEN. The biological significance of findings from recent studies is discussed and illustrates the breadth of cellular functions of PTEN that can be discovered by these approaches.
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Affiliation(s)
- Sarah L Smith
- School of Life and Health Sciences, Aston Triangle, Aston University, B4 7ET, Birmingham, U.K
| | - Andrew R Pitt
- School of Life and Health Sciences, Aston Triangle, Aston University, B4 7ET, Birmingham, U.K.,Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN, U.K
| | - Corinne M Spickett
- School of Life and Health Sciences, Aston Triangle, Aston University, B4 7ET, Birmingham, U.K
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152
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Alao JP, Johansson-Sjölander J, Rallis C, Sunnerhagen P. Caffeine Stabilises Fission Yeast Wee1 in a Rad24-Dependent Manner but Attenuates Its Expression in Response to DNA Damage. Microorganisms 2020; 8:microorganisms8101512. [PMID: 33008060 PMCID: PMC7600152 DOI: 10.3390/microorganisms8101512] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 09/17/2020] [Accepted: 09/24/2020] [Indexed: 12/12/2022] Open
Abstract
The widely consumed neuroactive compound caffeine has generated much interest due to its ability to override the DNA damage and replication checkpoints. Previously Rad3 and its homologues was thought to be the target of caffeine’s inhibitory activity. Later findings indicate that the Target of Rapamycin Complex 1 (TORC1) is the preferred target of caffeine. Effective Cdc2 inhibition requires both the activation of the Wee1 kinase and inhibition of the Cdc25 phosphatase. The TORC1, DNA damage, and environmental stress response pathways all converge on Cdc25 and Wee1. We previously demonstrated that caffeine overrides DNA damage checkpoints by modulating Cdc25 stability. The effect of caffeine on cell cycle progression resembles that of TORC1 inhibition. Furthermore, caffeine activates the Sty1 regulated environmental stress response. Caffeine may thus modulate multiple signalling pathways that regulate Cdc25 and Wee1 levels, localisation and activity. Here we show that the activity of caffeine stabilises both Cdc25 and Wee1. The stabilising effect of caffeine and genotoxic agents on Wee1 was dependent on the Rad24 chaperone. Interestingly, caffeine inhibited the accumulation of Wee1 in response to DNA damage. Caffeine may modulate cell cycle progression through increased Cdc25 activity and Wee1 repression following DNA damage via TORC1 inhibition, as TORC1 inhibition increased DNA damage sensitivity.
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Affiliation(s)
- John P Alao
- School of Health, Sports and Bioscience, University of East London, Stratford Campus, London E15 4LZ, UK
- Department of Chemistry and Molecular Biology, University of Gothenburg, P.O. Box 462, SE-405 30 Gothenburg, Sweden
| | - Johanna Johansson-Sjölander
- Department of Chemistry and Molecular Biology, University of Gothenburg, P.O. Box 462, SE-405 30 Gothenburg, Sweden
| | - Charalampos Rallis
- School of Health, Sports and Bioscience, University of East London, Stratford Campus, London E15 4LZ, UK
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Per Sunnerhagen
- Department of Chemistry and Molecular Biology, University of Gothenburg, P.O. Box 462, SE-405 30 Gothenburg, Sweden
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153
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Kouloulia S, Hallin EI, Simbriger K, Amorim IS, Lach G, Amvrosiadis T, Chalkiadaki K, Kampaite A, Truong VT, Hooshmandi M, Jafarnejad SM, Skehel P, Kursula P, Khoutorsky A, Gkogkas CG. Raptor-Mediated Proteasomal Degradation of Deamidated 4E-BP2 Regulates Postnatal Neuronal Translation and NF-κB Activity. Cell Rep 2020; 29:3620-3635.e7. [PMID: 31825840 PMCID: PMC6915327 DOI: 10.1016/j.celrep.2019.11.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 09/06/2019] [Accepted: 11/06/2019] [Indexed: 12/14/2022] Open
Abstract
The translation initiation repressor 4E-BP2 is deamidated in the brain on asparagines N99/N102 during early postnatal brain development. This post-translational modification enhances 4E-BP2 association with Raptor, a central component of mTORC1 and alters the kinetics of excitatory synaptic transmission. We show that 4E-BP2 deamidation is neuron specific, occurs in the human brain, and changes 4E-BP2 subcellular localization, but not its disordered structure state. We demonstrate that deamidated 4E-BP2 is ubiquitinated more and degrades faster than the unmodified protein. We find that enhanced deamidated 4E-BP2 degradation is dependent on Raptor binding, concomitant with increased association with a Raptor-CUL4B E3 ubiquitin ligase complex. Deamidated 4E-BP2 stability is promoted by inhibiting mTORC1 or glutamate receptors. We further demonstrate that deamidated 4E-BP2 regulates the translation of a distinct pool of mRNAs linked to cerebral development, mitochondria, and NF-κB activity, and thus may be crucial for postnatal brain development in neurodevelopmental disorders, such as ASD. Deamidated 4E-BP2 occurs in neurons and is susceptible to ubiquitination/degradation mTORC1 or glutamate receptor inhibition stabilizes deamidated 4E-BP2 A Raptor-CUL4B ubiquitin ligase complex binds to deamidated 4E-BP2 Deamidated 4E-BP2 regulates postnatal brain translation and NF-κB activity
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Affiliation(s)
- Stella Kouloulia
- Centre for Discovery Brain Sciences and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Erik I Hallin
- Department of Biomedicine, University of Bergen, Bergen N-5020, Norway
| | - Konstanze Simbriger
- Centre for Discovery Brain Sciences and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Inês S Amorim
- Centre for Discovery Brain Sciences and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Gilliard Lach
- Centre for Discovery Brain Sciences and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Theoklitos Amvrosiadis
- Centre for Discovery Brain Sciences and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Kleanthi Chalkiadaki
- Centre for Discovery Brain Sciences and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Agniete Kampaite
- Centre for Discovery Brain Sciences and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Vinh Tai Truong
- Department of Anesthesia and Alan Edwards Centre for Research on Pain, McGill University, Montréal H3A 0G1, QC, Canada
| | - Mehdi Hooshmandi
- Department of Anesthesia and Alan Edwards Centre for Research on Pain, McGill University, Montréal H3A 0G1, QC, Canada
| | - Seyed Mehdi Jafarnejad
- Centre for Cancer Research and Cell Biology, Queen's University of Belfast, Belfast BT9 7AE, UK
| | - Paul Skehel
- Centre for Discovery Brain Sciences and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Petri Kursula
- Department of Biomedicine, University of Bergen, Bergen N-5020, Norway; Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu FI-90014, Finland
| | - Arkady Khoutorsky
- Department of Anesthesia and Alan Edwards Centre for Research on Pain, McGill University, Montréal H3A 0G1, QC, Canada.
| | - Christos G Gkogkas
- Centre for Discovery Brain Sciences and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK; Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, UK.
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154
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Xu D, Zhao H, Jin M, Zhu H, Shan B, Geng J, Dziedzic SA, Amin P, Mifflin L, Naito MG, Najafov A, Xing J, Yan L, Liu J, Qin Y, Hu X, Wang H, Zhang M, Manuel VJ, Tan L, He Z, Sun ZJ, Lee VMY, Wagner G, Yuan J. Modulating TRADD to restore cellular homeostasis and inhibit apoptosis. Nature 2020; 587:133-138. [PMID: 32968279 DOI: 10.1038/s41586-020-2757-z] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Accepted: 07/01/2020] [Indexed: 01/26/2023]
Abstract
Cell death in human diseases is often a consequence of disrupted cellular homeostasis. If cell death is prevented without restoring cellular homeostasis, it may lead to a persistent dysfunctional and pathological state. Although mechanisms of cell death have been thoroughly investigated1-3, it remains unclear how homeostasis can be restored after inhibition of cell death. Here we identify TRADD4-6, an adaptor protein, as a direct regulator of both cellular homeostasis and apoptosis. TRADD modulates cellular homeostasis by inhibiting K63-linked ubiquitination of beclin 1 mediated by TRAF2, cIAP1 and cIAP2, thereby reducing autophagy. TRADD deficiency inhibits RIPK1-dependent extrinsic apoptosis and proteasomal stress-induced intrinsic apoptosis. We also show that the small molecules ICCB-19 and Apt-1 bind to a pocket on the N-terminal TRAF2-binding domain of TRADD (TRADD-N), which interacts with the C-terminal domain (TRADD-C) and TRAF2 to modulate the ubiquitination of RIPK1 and beclin 1. Inhibition of TRADD by ICCB-19 or Apt-1 blocks apoptosis and restores cellular homeostasis by activating autophagy in cells with accumulated mutant tau, α-synuclein, or huntingtin. Treatment with Apt-1 restored proteostasis and inhibited cell death in a mouse model of proteinopathy induced by mutant tau(P301S). We conclude that pharmacological targeting of TRADD may represent a promising strategy for inhibiting cell death and restoring homeostasis to treat human diseases.
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Affiliation(s)
- Daichao Xu
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA.,Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Heng Zhao
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Minzhi Jin
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Hong Zhu
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Bing Shan
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Jiefei Geng
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | | | - Palak Amin
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Lauren Mifflin
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | | | - Ayaz Najafov
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Jing Xing
- Department of Pediatrics and Human Development, Michigan State University, Grand Rapids, MI, USA
| | - Lingjie Yan
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Jianping Liu
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Ying Qin
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Xinqian Hu
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Huibing Wang
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Mengmeng Zhang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Vica Jean Manuel
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Li Tan
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Zhuohao He
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.,Center for Neurodegenerative Disease Research, Institute on Aging, Department of Pathology and Laboratory, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Zhenyu J Sun
- Department of Cancer Biology, Dana Farber Cancer Institute, Boston, MA, USA
| | - Virginia M Y Lee
- Center for Neurodegenerative Disease Research, Institute on Aging, Department of Pathology and Laboratory, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Gerhard Wagner
- Department of Biochemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Junying Yuan
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
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155
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Pharmacological and nutritional modulation of autophagy in a rainbow trout (Oncorhynchus mykiss) gill cell line, RTgill-W1. In Vitro Cell Dev Biol Anim 2020; 56:659-669. [PMID: 32901427 DOI: 10.1007/s11626-020-00490-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 08/06/2020] [Indexed: 12/12/2022]
Abstract
Autophagy is involved in the modulation of nutrition, immunity, and disease in humans and animals. To understand the impact of autophagy modulation on a rainbow trout gill cell line, RTgill-W1, treatments including reduced nutrition (2% fetal bovine serum compared with 10% control), rapamycin, 3-methyladenine, deoxynivalenol, and chloroquine were tested. Western blot and immunofluorescence were used to detect microtubule-associated protein 1A/1B-light chain protein and quantitative polymerase chain reaction was used to detect the expression of 10 autophagy-related genes. At 3-d post-treatment, reduced nutrition significantly (p < 0.05) increased autophagy while deoxynivalenol significantly (p < 0.01) suppressed it compared to controls. These phenomena were confirmed by using immunofluorescence to detect the number of autophagosomes in RTgill-W1. Chloroquine is critical to allow observation of microtubule-associated protein 1A/1B-light chain protein in this model. The commonly used autophagy-modulating chemicals rapamycin and 3-methyladenine either activated or suppressed microtubule-associated protein 1A/1B-light chain protein, respectively, as expected from the literature, but did not act in a consistently significant manner. Expression of five of the 10 Atg genes, including lc3, gabarap, atg4, atg7, and atg12, were altered in a similar pattern to microtubule-associated protein 1A/1B-light chain protein. The consistent trend of autophagy-related gene upregulation including becn1, lc3, gabarap, and atg9 following treatment with 3-methyladenine and chloroquine is suggestive of a novel feedback regulation in the autophagy machinery.
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156
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Navarro I Batista K, Schraner M, Riediger T. Brainstem prolactin-releasing peptide contributes to cancer anorexia-cachexia syndrome in rats. Neuropharmacology 2020; 180:108289. [PMID: 32890590 DOI: 10.1016/j.neuropharm.2020.108289] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 08/05/2020] [Accepted: 08/25/2020] [Indexed: 11/26/2022]
Abstract
Up to 80% of cancer patients are affected by the cancer anorexia-cachexia syndrome (CACS), which leads to excessive body weight loss, reduced treatment success and increased lethality. The area postrema/nucleus of the solitary tract (AP/NTS) region emerged as a central nervous key structure in this multi-factorial process. Neurons in this area are targeted by cytokines and signal to downstream sites involved in energy homeostasis. NTS neurons expressing prolactin-releasing peptide (PrRP) are implicated in the control of energy intake and hypothalamus-pituitary-adrenal (HPA) axis activation, which contributes to muscle wasting. To explore if brainstem PrRP neurons contribute to CACS, we selectively knocked down PrRP expression in the NTS of hepatoma tumor-bearing rats by an AAV/shRNA gene silencing approach. PrRP knockdown reduced body weight loss and anorexia compared to tumor-bearing controls treated with a non-silencing AAV. Gastrocnemius and total hind limb muscle weight was higher in PrPR knockdown rats. Corticosterone levels were increased in the early phase after tumor induction at day 6 in both groups but returned to baseline levels at day 21 in the PrRP knockdown group. While we did not detect significant changes in gene expression of markers for muscle protein metabolism (MuRF-1, myostatin, mTOR and REDD1), mTOR and REDD1 tended to be lower after disruption PrRP signalling. In conclusion, we identified brainstem PrRP as a possible neuropeptide mediator of CACS in hepatoma tumor-bearing rats. The central and peripheral downstream mechanisms require further investigation and might involve HPA axis activation.
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Affiliation(s)
| | - Marissa Schraner
- University of Zurich, Institute of Veterinary Physiology, Zurich, Switzerland
| | - Thomas Riediger
- University of Zurich, Institute of Veterinary Physiology, Zurich, Switzerland.
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157
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Tundo GR, Sbardella D, Santoro AM, Coletta A, Oddone F, Grasso G, Milardi D, Lacal PM, Marini S, Purrello R, Graziani G, Coletta M. The proteasome as a druggable target with multiple therapeutic potentialities: Cutting and non-cutting edges. Pharmacol Ther 2020; 213:107579. [PMID: 32442437 PMCID: PMC7236745 DOI: 10.1016/j.pharmthera.2020.107579] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 05/05/2020] [Indexed: 01/10/2023]
Abstract
Ubiquitin Proteasome System (UPS) is an adaptable and finely tuned system that sustains proteostasis network under a large variety of physiopathological conditions. Its dysregulation is often associated with the onset and progression of human diseases; hence, UPS modulation has emerged as a promising new avenue for the development of treatments of several relevant pathologies, such as cancer and neurodegeneration. The clinical interest in proteasome inhibition has considerably increased after the FDA approval in 2003 of bortezomib for relapsed/refractory multiple myeloma, which is now used in the front-line setting. Thereafter, two other proteasome inhibitors (carfilzomib and ixazomib), designed to overcome resistance to bortezomib, have been approved for treatment-experienced patients, and a variety of novel inhibitors are currently under preclinical and clinical investigation not only for haematological malignancies but also for solid tumours. However, since UPS collapse leads to toxic misfolded proteins accumulation, proteasome is attracting even more interest as a target for the care of neurodegenerative diseases, which are sustained by UPS impairment. Thus, conceptually, proteasome activation represents an innovative and largely unexplored target for drug development. According to a multidisciplinary approach, spanning from chemistry, biochemistry, molecular biology to pharmacology, this review will summarize the most recent available literature regarding different aspects of proteasome biology, focusing on structure, function and regulation of proteasome in physiological and pathological processes, mostly cancer and neurodegenerative diseases, connecting biochemical features and clinical studies of proteasome targeting drugs.
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Affiliation(s)
- G R Tundo
- Department of Clinical Sciences and Translational Medicine, University of Rome Tor Vergata, Rome, Italy.
| | | | - A M Santoro
- CNR, Institute of Crystallography, Catania, Italy
| | - A Coletta
- Department of Chemistry, University of Aarhus, Aarhus, Denmark
| | - F Oddone
- IRCCS-Fondazione Bietti, Rome, Italy
| | - G Grasso
- Department of Chemical Sciences, University of Catania, Catania, Italy
| | - D Milardi
- CNR, Institute of Crystallography, Catania, Italy
| | - P M Lacal
- Laboratory of Molecular Oncology, IDI-IRCCS, Rome, Italy
| | - S Marini
- Department of Clinical Sciences and Translational Medicine, University of Rome Tor Vergata, Rome, Italy
| | - R Purrello
- Department of Chemical Sciences, University of Catania, Catania, Italy
| | - G Graziani
- Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy.
| | - M Coletta
- Department of Clinical Sciences and Translational Medicine, University of Rome Tor Vergata, Rome, Italy.
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158
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Qin G, Xu D, Lou B, Chen R, Wang L, Tan P. iTRAQ-based quantitative phosphoproteomics provides insights into the metabolic and physiological responses of a carnivorous marine fish (Nibea albiflora) fed a linseed oil-rich diet. J Proteomics 2020; 228:103917. [DOI: 10.1016/j.jprot.2020.103917] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 06/04/2020] [Accepted: 07/20/2020] [Indexed: 02/01/2023]
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159
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Multiple myeloma cells are exceptionally sensitive to heat shock, which overwhelms their proteostasis network and induces apoptosis. Proc Natl Acad Sci U S A 2020; 117:21588-21597. [PMID: 32817432 DOI: 10.1073/pnas.2001323117] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Proteasome inhibitors, such as bortezomib (BTZ), are highly effective and widely used treatments for multiple myeloma. One proposed reason for myeloma cells' exceptional sensitivity to proteasome inhibition is that they produce and continually degrade unusually large amounts of abnormal immunoglobulins. We, therefore, hypothesized that, heat shock may also be especially toxic to myeloma cells by causing protein unfolding, increasing further the substrate load on proteasomes, and, thus, putting further stress on their capacity for protein homeostasis. After a shift from 37 to 43 °C, all four myeloma lines studied underwent extensive apoptosis in 4 h, unlike 13 nonmyeloma cell lines, even though the myeloma cells induced heat-shock proteins and increased protein degradation similar to other cells. Furthermore, two myeloma lines resistant to proteasome inhibitors were also more resistant to 43 °C. Shifting myeloma cells to 43, 41, or 39 °C (which was not cytotoxic) dramatically increased their killing by proteasome inhibitors and inhibitors of ubiquitination or p97/VCP. Combining increased temperature with BTZ increased the accumulation of misfolded proteins and substrate load on the 26S proteasome. The apoptosis seen at 43 °C and at 39 °C with BTZ was mediated by caspase-9 and was linked to an accumulation of the proapoptotic Bcl-2-family member Noxa. Thus, myeloma cells are exceptionally sensitive to increased temperatures, which greatly increase substrate load on the ubiquitin-proteasome system and eventually activate the intrinsic apoptotic pathway. Consequently, for myeloma, mild hyperthermia may be a beneficial approach to enhance the therapeutic efficacy of proteasome inhibitors.
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160
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Colella B, Colardo M, Iannone G, Contadini C, Saiz-Ladera C, Fuoco C, Barilà D, Velasco G, Segatto M, Di Bartolomeo S. mTOR Inhibition Leads to Src-Mediated EGFR Internalisation and Degradation in Glioma Cells. Cancers (Basel) 2020; 12:E2266. [PMID: 32823532 PMCID: PMC7464593 DOI: 10.3390/cancers12082266] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 08/06/2020] [Accepted: 08/11/2020] [Indexed: 12/16/2022] Open
Abstract
Epidermal Growth Factor receptor (EGFR) is a tyrosine kinase receptor widely expressed on the surface of numerous cell types, which activates several downstream signalling pathways involved in cell proliferation, migration and survival. EGFR alterations, such as overexpression or mutations, have been frequently observed in several cancers, including glioblastoma (GBM), and are associated to uncontrolled cell proliferation. Here we show that the inhibition of mammalian target of Rapamycin (mTOR) mediates EGFR delivery to lysosomes for degradation in GBM cells, independently of autophagy activation. Coherently with EGFR internalisation and degradation, mTOR blockade negatively affects the mitogen activated protein/extracellular signal-regulated kinase (MAPK)/ERK pathway. Furthermore, we provide evidence that Src kinase activation is required for EGFR internaliation upon mTOR inhibition. Our results further support the hypothesis that mTOR targeting may represent an effective therapeutic strategy in GBM management, as its inhibition results in EGFR degradation and in proliferative signal alteration.
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Affiliation(s)
- Barbara Colella
- Department of Biosciences and Territory, University of Molise, 86090 Pesche (IS), Italy; (B.C.); (M.C.); (G.I.); (M.S.)
| | - Mayra Colardo
- Department of Biosciences and Territory, University of Molise, 86090 Pesche (IS), Italy; (B.C.); (M.C.); (G.I.); (M.S.)
| | - Gianna Iannone
- Department of Biosciences and Territory, University of Molise, 86090 Pesche (IS), Italy; (B.C.); (M.C.); (G.I.); (M.S.)
| | - Claudia Contadini
- Department of Biology, University of RomeTor Vergata, 00133 Rome, Italy; (C.C.); (C.F.); (D.B.)
- Laboratory of Cell Signaling, Istituto di Ricovero e Cura a carattere Scientifico (IRCSS) Fondazione Santa Lucia, 00179 Rome, Italy
| | - Cristina Saiz-Ladera
- Department of Biochemistry and Molecular Biology, School of Biology, Complutense University and Instituto de Investigaciones Sanitarias San Carlos (IdISSC), 28040 Madrid, Spain; (C.S.-L.); (G.V.)
| | - Claudia Fuoco
- Department of Biology, University of RomeTor Vergata, 00133 Rome, Italy; (C.C.); (C.F.); (D.B.)
| | - Daniela Barilà
- Department of Biology, University of RomeTor Vergata, 00133 Rome, Italy; (C.C.); (C.F.); (D.B.)
- Laboratory of Cell Signaling, Istituto di Ricovero e Cura a carattere Scientifico (IRCSS) Fondazione Santa Lucia, 00179 Rome, Italy
| | - Guillermo Velasco
- Department of Biochemistry and Molecular Biology, School of Biology, Complutense University and Instituto de Investigaciones Sanitarias San Carlos (IdISSC), 28040 Madrid, Spain; (C.S.-L.); (G.V.)
| | - Marco Segatto
- Department of Biosciences and Territory, University of Molise, 86090 Pesche (IS), Italy; (B.C.); (M.C.); (G.I.); (M.S.)
| | - Sabrina Di Bartolomeo
- Department of Biosciences and Territory, University of Molise, 86090 Pesche (IS), Italy; (B.C.); (M.C.); (G.I.); (M.S.)
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161
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Wolff CA, Reid JJ, Musci RV, Linden MA, Konopka AR, Peelor FF, Miller BF, Hamilton KL, Bruns DR. Differential Effects of Rapamycin and Metformin in Combination With Rapamycin on Mechanisms of Proteostasis in Cultured Skeletal Myotubes. J Gerontol A Biol Sci Med Sci 2020; 75:32-39. [PMID: 30820523 DOI: 10.1093/gerona/glz058] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 02/23/2019] [Indexed: 12/12/2022] Open
Abstract
mTOR inhibition extends life span in multiple organisms. In mice, when metformin treatment (Met) is added to the mTOR inhibitor rapamycin (Rap), median and maximal life span is extended to a greater degree than with Rap or Met alone. Treatments that extend life span often maintain proteostasis. However, it is less clear how individual tissues, such as skeletal muscle, maintain proteostasis with life span-extending treatments. In C2C12 myotubes, we used deuterium oxide (D2O) to directly measure two primary determinants of proteostasis, protein synthesis, and degradation rates, with Rap or Met+Rap treatments. We accounted for the independent effects of cell growth and loss, and isolated the contribution of autophagy and mitochondrial fission to obtain a comprehensive assessment of protein turnover. Compared with control, both Rap and Met+Rap treatments lowered mitochondrial protein synthesis rates (p < .001) and slowed cellular proliferation (p < .01). These changes resulted in greater activation of mechanisms promoting proteostasis for Rap, but not Met+Rap. Compared with control, both Rap and Met+Rap slowed protein breakdown. Autophagy and mitochondrial fission differentially influenced the proteostatic effects of Rap and Met+Rap in C2C12 myotubes. In conclusion, we demonstrate that Met+Rap did not increase protein turnover and that these treatments do not seem to promote proteostasis through increased autophagy.
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Affiliation(s)
- Christopher A Wolff
- Department of Health and Exercise Science, Colorado State University, Fort Collins
| | - Justin J Reid
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City
| | - Robert V Musci
- Department of Health and Exercise Science, Colorado State University, Fort Collins
| | - Melissa A Linden
- Department of Health and Exercise Science, Colorado State University, Fort Collins
| | - Adam R Konopka
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign
| | - Frederick F Peelor
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City
| | - Benjamin F Miller
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City
| | - Karyn L Hamilton
- Department of Health and Exercise Science, Colorado State University, Fort Collins
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162
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Johri MK, Lashkari HV, Gupta D, Vedagiri D, Harshan KH. mTORC1 restricts hepatitis C virus RNA replication through ULK1-mediated suppression of miR-122 and facilitates post-replication events. J Gen Virol 2020; 101:86-95. [PMID: 31821132 DOI: 10.1099/jgv.0.001356] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR), an important kinase that assimilates several upstream signals, associates into two functional complexes, mTORC1 and mTORC2. In this study, we demonstrate that HCV infection activates mTORC1 that functions in important antiviral response. Pharmacological inhibition of mTOR complexes augmented cellular HCV RNA levels, the observation confirmed further by Raptor depletion, indicating antiviral roles of mTORC1. ULK1 depletion phenocopied mTOR inhibition and thus suggested that mTORC1 restricts HCV replication through ULK1. We reveal that ULK1 depletion augmented the levels of miR-122, a critical host factor for HCV replication, thus possibly regulating HCV replication. The increase in HCV RNA levels, however, failed to augment intracellular infectious virion production, reflecting a lower rate of virion assembly. Higher intracellular HCV RNA levels, however, did not result in a corresponding increase in HCV RNA and infectious titres in mTOR inhibited supernatants, but in contrast showed a consistent drop, confirming defective viral assembly caused by the inhibition. Consistent with this, the mTOR activator caused a significant drop in HCV RNA levels both in infected cells and in the supernatant. Our results demonstrate that ULK1 depletion did not affect autophagy, suggesting that ULK1-mediated HCV regulation is autophagy independent. Together, our data demonstrate that mTORC1 functions to suppress HCV RNA replication, but facilitates the virion packaging and release. Our studies reveal that the activation of mTOR by HCV infection is an antiviral measure by the cells.
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Affiliation(s)
- Manish Kumar Johri
- Academy of Scientific and Innovative Research (AcSIR), CSIR-CCMB Campus, Hyderabad, India.,CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad-500007, India
| | | | - Divya Gupta
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad-500007, India
| | - Dhiviya Vedagiri
- Academy of Scientific and Innovative Research (AcSIR), CSIR-CCMB Campus, Hyderabad, India.,CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad-500007, India
| | - Krishnan Harinivas Harshan
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad-500007, India.,Academy of Scientific and Innovative Research (AcSIR), CSIR-CCMB Campus, Hyderabad, India
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163
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Lynch GM, Murphy CH, Castro EDM, Roche HM. Inflammation and metabolism: the role of adiposity in sarcopenic obesity. Proc Nutr Soc 2020; 79:1-13. [PMID: 32669148 DOI: 10.1017/s0029665120007119] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Sarcopenic obesity is characterised by the double burden of diminished skeletal muscle mass and the presence of excess adiposity. From a mechanistic perspective, both obesity and sarcopenia are associated with sub-acute, chronic pro-inflammatory states that impede metabolic processes, disrupting adipose and skeletal functionality, which may potentiate disease. Recent evidence suggests that there is an important cross-talk between metabolism and inflammation, which has shifted focus upon metabolic-inflammation as a key emerging biological interaction. Dietary intake, physical activity and nutritional status are important environmental factors that may modulate metabolic-inflammation. This paradigm will be discussed within the context of sarcopenic obesity risk. There is a paucity of data in relation to the nature and the extent to which nutritional status affects metabolic-inflammation in sarcopenic obesity. Research suggests that there may be scope for the modulation of sarcopenic obesity with alterations in diet. The potential impact of increasing protein consumption and reconfiguration of dietary fat composition in human dietary interventions are evaluated. This review will explore emerging data with respect to if and how different dietary components may modulate metabolic-inflammation, particularly with respect to adiposity, within the context of sarcopenic obesity.
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Affiliation(s)
- G M Lynch
- Nutrigenomics Research Group, School of Public Health, Physiotherapy and Sports Science, UCD Institute of Food and Health, Diabetes Complications Research Centre, University College Dublin, Dublin, Ireland
| | - C H Murphy
- Nutrigenomics Research Group, School of Public Health, Physiotherapy and Sports Science, UCD Institute of Food and Health, Diabetes Complications Research Centre, University College Dublin, Dublin, Ireland
| | - E de Marco Castro
- Nutrigenomics Research Group, School of Public Health, Physiotherapy and Sports Science, UCD Institute of Food and Health, Diabetes Complications Research Centre, University College Dublin, Dublin, Ireland
| | - H M Roche
- Nutrigenomics Research Group, School of Public Health, Physiotherapy and Sports Science, UCD Institute of Food and Health, Diabetes Complications Research Centre, University College Dublin, Dublin, Ireland
- Institute for Global Food Security, Queen's University Belfast, Belfast, UK
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164
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Peroxisome Proliferator-Activated Receptors and Caloric Restriction-Common Pathways Affecting Metabolism, Health, and Longevity. Cells 2020; 9:cells9071708. [PMID: 32708786 PMCID: PMC7407644 DOI: 10.3390/cells9071708] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/14/2020] [Accepted: 07/14/2020] [Indexed: 02/06/2023] Open
Abstract
Caloric restriction (CR) is a traditional but scientifically verified approach to promoting health and increasing lifespan. CR exerts its effects through multiple molecular pathways that trigger major metabolic adaptations. It influences key nutrient and energy-sensing pathways including mammalian target of rapamycin, Sirtuin 1, AMP-activated protein kinase, and insulin signaling, ultimately resulting in reductions in basic metabolic rate, inflammation, and oxidative stress, as well as increased autophagy and mitochondrial efficiency. CR shares multiple overlapping pathways with peroxisome proliferator-activated receptors (PPARs), particularly in energy metabolism and inflammation. Consequently, several lines of evidence suggest that PPARs might be indispensable for beneficial outcomes related to CR. In this review, we present the available evidence for the interconnection between CR and PPARs, highlighting their shared pathways and analyzing their interaction. We also discuss the possible contributions of PPARs to the effects of CR on whole organism outcomes.
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165
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Tyagi A, Kamal MA, Poddar NK. Integrated Pathways of COX-2 and mTOR: Roles in Cell Sensing and Alzheimer's Disease. Front Neurosci 2020; 14:693. [PMID: 32742252 PMCID: PMC7364283 DOI: 10.3389/fnins.2020.00693] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 06/08/2020] [Indexed: 12/12/2022] Open
Abstract
Cyclooxygenases (COX) are enzymes catalyzing arachidonic acid into prostanoids. COX exists in three isoforms: COX-1, 2, and 3. COX-1 and COX-2 have been widely studied in order to explore and understand their involvement in Alzheimer’s disease (AD), a progressive neuroinflammatory dementia. COX-2 was traditionally viewed to be expressed only under pathological conditions and to have detrimental effects in AD pathophysiology and neurodegeneration. However, an increasing number of reports point to much more complex roles of COX-2 in AD. Mammalian/mechanistic target of rapamycin (mTOR) has been considered as a hub which integrates multiple signaling cascades, some of which are also involved in AD progression. COX-2 and mTOR are both involved in environmental sensing, growth, and metabolic processes of the cell. They are also known to act in cooperation in many different cancers and thus, their role together in normal cellular functions as well as AD has been explored in this review. Some of the therapeutic approaches targeting COX-2 and mTOR in AD and cancer are also discussed.
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Affiliation(s)
- Arti Tyagi
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, New Delhi, India
| | - Mohammad A Kamal
- King Fahad Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.,Enzymoics, Hebersham, NSW, Australia
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166
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Vainshtein A, Sandri M. Signaling Pathways That Control Muscle Mass. Int J Mol Sci 2020; 21:ijms21134759. [PMID: 32635462 PMCID: PMC7369702 DOI: 10.3390/ijms21134759] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 06/23/2020] [Accepted: 07/01/2020] [Indexed: 12/12/2022] Open
Abstract
The loss of skeletal muscle mass under a wide range of acute and chronic maladies is associated with poor prognosis, reduced quality of life, and increased mortality. Decades of research indicate the importance of skeletal muscle for whole body metabolism, glucose homeostasis, as well as overall health and wellbeing. This tissue’s remarkable ability to rapidly and effectively adapt to changing environmental cues is a double-edged sword. Physiological adaptations that are beneficial throughout life become maladaptive during atrophic conditions. The atrophic program can be activated by mechanical, oxidative, and energetic distress, and is influenced by the availability of nutrients, growth factors, and cytokines. Largely governed by a transcription-dependent mechanism, this program impinges on multiple protein networks including various organelles as well as biosynthetic and quality control systems. Although modulating muscle function to prevent and treat disease is an enticing concept that has intrigued research teams for decades, a lack of thorough understanding of the molecular mechanisms and signaling pathways that control muscle mass, in addition to poor transferability of findings from rodents to humans, has obstructed efforts to develop effective treatments. Here, we review the progress made in unraveling the molecular mechanisms responsible for the regulation of muscle mass, as this continues to be an intensive area of research.
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Affiliation(s)
| | - Marco Sandri
- Veneto Institute of Molecular Medicine, via Orus 2, 35129 Padua, Italy
- Department of Biomedical Science, University of Padua, via G. Colombo 3, 35100 Padua, Italy
- Myology Center, University of Padua, via G. Colombo 3, 35100 Padova, Italy
- Department of Medicine, McGill University, Montreal, QC H3A 0G4, Canada
- Correspondence:
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167
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An H, Ordureau A, Körner M, Paulo JA, Harper JW. Systematic quantitative analysis of ribosome inventory during nutrient stress. Nature 2020; 583:303-309. [PMID: 32612236 PMCID: PMC7351614 DOI: 10.1038/s41586-020-2446-y] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Accepted: 05/07/2020] [Indexed: 12/14/2022]
Abstract
Mammalian cells reorganize their proteomes in response to nutrient stress through translational suppression and degradative mechanisms using the proteasome and autophagy systems1,2. Ribosomes are central targets of this response, as they are responsible for translation and subject to lysosomal turnover during nutrient stress3-5. The abundance of ribosomal (r)-proteins (around 6% of the proteome; 107 copies per cell)6,7 and their high arginine and lysine content has led to the hypothesis that they are selectively used as a source of basic amino acids during nutrient stress through autophagy4,7. However, the relative contributions of translational and degradative mechanisms to the control of r-protein abundance during acute stress responses is poorly understood, as is the extent to which r-proteins are used to generate amino acids when specific building blocks are limited7. Here, we integrate quantitative global translatome and degradome proteomics8 with genetically encoded Ribo-Keima5 and Ribo-Halo reporters to interrogate r-protein homeostasis with and without active autophagy. In conditions of acute nutrient stress, cells strongly suppress the translation of r-proteins, but, notably, r-protein degradation occurs largely through non-autophagic pathways. Simultaneously, the decrease in r-protein abundance is compensated for by a reduced dilution of pre-existing ribosomes and a reduction in cell volume, thereby maintaining the density of ribosomes within single cells. Withdrawal of basic or hydrophobic amino acids induces translational repression without differential induction of ribophagy, indicating that ribophagy is not used to selectively produce basic amino acids during acute nutrient stress. We present a quantitative framework that describes the contributions of biosynthetic and degradative mechanisms to r-protein abundance and proteome remodelling in conditions of nutrient stress.
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Affiliation(s)
- Heeseon An
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Alban Ordureau
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Maria Körner
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Department of Biochemistry, University of Würzburg, Würzburg, Germany
| | - Joao A Paulo
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - J Wade Harper
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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168
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Kubra KT, Akhter MS, Uddin MA, Barabutis N. Unfolded protein response in cardiovascular disease. Cell Signal 2020; 73:109699. [PMID: 32592779 DOI: 10.1016/j.cellsig.2020.109699] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 06/20/2020] [Accepted: 06/21/2020] [Indexed: 12/21/2022]
Abstract
The unfolded protein response (UPR) is a highly conserved molecular machinery, which protects the cells against a diverse variety of stimuli. Activation of this element has been associated with both human health and disease. The purpose of the current manuscript is to provide the most updated information on the involvement of UPR towards the improvement; or deterioration of cardiovascular functions. Since UPR is consisted of three distinct elements, namely the activating transcription factor 6, the protein kinase RNA-like endoplasmic reticulum kinase; and the inositol-requiring enzyme-1α, a highly orchestrated manipulation of those molecular branches may provide new therapeutic possibilities against the severe outcomes of cardiovascular disease.
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Affiliation(s)
- Khadeja-Tul Kubra
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201, USA
| | - Mohammad S Akhter
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201, USA
| | - Mohammad A Uddin
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201, USA
| | - Nektarios Barabutis
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201, USA.
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169
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Asrani K, Murali S, Lam B, Na CH, Phatak P, Sood A, Kaur H, Khan Z, Noë M, Anchoori RK, Talbot CC, Smith B, Skaro M, Lotan TL. mTORC1 feedback to AKT modulates lysosomal biogenesis through MiT/TFE regulation. J Clin Invest 2020; 129:5584-5599. [PMID: 31527310 DOI: 10.1172/jci128287] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 09/10/2019] [Indexed: 01/02/2023] Open
Abstract
The microphthalmia family of transcription factors (MiT/TFEs) controls lysosomal biogenesis and is negatively regulated by the nutrient sensor mTORC1. However, the mechanisms by which cells with constitutive mTORC1 signaling maintain lysosomal catabolism remain to be elucidated. Using the murine epidermis as a model system, we found that epidermal Tsc1 deletion resulted in a phenotype characterized by wavy hair and curly whiskers, and was associated with increased EGFR and HER2 degradation. Unexpectedly, constitutive mTORC1 activation with Tsc1 loss increased lysosomal content via upregulated expression and activity of MiT/TFEs, whereas genetic deletion of Rheb or Rptor or prolonged pharmacologic mTORC1 inactivation had the reverse effect. This paradoxical increase in lysosomal biogenesis by mTORC1 was mediated by feedback inhibition of AKT, and a resulting suppression of AKT-induced MiT/TFE downregulation. Thus, inhibiting hyperactive AKT signaling in the context of mTORC1 loss-of-function fully restored MiT/TFE expression and activity. These data suggest that signaling feedback loops work to restrain or maintain cellular lysosomal content during chronically inhibited or constitutively active mTORC1 signaling, respectively, and reveal a mechanism by which mTORC1 regulates upstream receptor tyrosine kinase signaling.
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Affiliation(s)
| | | | | | - Chan-Hyun Na
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Pornima Phatak
- Baltimore Veteran Affairs Medical Center, Baltimore, Maryland, USA
| | | | | | | | | | | | | | - Barbara Smith
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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170
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cGMP via PKG activates 26S proteasomes and enhances degradation of proteins, including ones that cause neurodegenerative diseases. Proc Natl Acad Sci U S A 2020; 117:14220-14230. [PMID: 32513741 PMCID: PMC7321992 DOI: 10.1073/pnas.2003277117] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Most studies of the regulation of proteolysis by the ubiquitin proteasome system have focused on the control of ubiquitination. However, it is now clear that the activity of the 26S proteasome and rates of protein degradation in cells are also tightly regulated through proteasome phosphorylation. Here we demonstrate that agents that raise cGMP and activate cGMP-dependent protein kinase (e.g., widely used phosphodiesterase 5 inhibitors) stimulate proteasome activities and intracellular proteolysis without affecting autophagy. Furthermore, we showed that raising cGMP reduced the levels of the disease-causing mutant tau in a zebrafish model by increasing its degradation, and also decreased the associated morphological abnormalities. Thus, activating the proteasome via cGMP is a promising strategy to prevent the progression of neurodegenerative diseases. Because raising cAMP enhances 26S proteasome activity and the degradation of cell proteins, including the selective breakdown of misfolded proteins, we investigated whether agents that raise cGMP may also regulate protein degradation. Treating various cell lines with inhibitors of phosphodiesterase 5 or stimulators of soluble guanylyl cyclase rapidly enhanced multiple proteasome activities and cellular levels of ubiquitinated proteins by activating protein kinase G (PKG). PKG stimulated purified 26S proteasomes by phosphorylating a different 26S component than is modified by protein kinase A. In cells and cell extracts, raising cGMP also enhanced within minutes ubiquitin conjugation to cell proteins. Raising cGMP, like raising cAMP, stimulated the degradation of short-lived cell proteins, but unlike cAMP, also markedly increased proteasomal degradation of long-lived proteins (the bulk of cell proteins) without affecting lysosomal proteolysis. We also tested if raising cGMP, like cAMP, can promote the degradation of mutant proteins that cause neurodegenerative diseases. Treating zebrafish models of tauopathies or Huntington’s disease with a PDE5 inhibitor reduced the levels of the mutant huntingtin and tau proteins, cell death, and the resulting morphological abnormalities. Thus, PKG rapidly activates cytosolic proteasomes, protein ubiquitination, and overall protein degradation, and agents that raise cGMP may help combat the progression of neurodegenerative diseases.
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171
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Limanaqi F, Busceti CL, Biagioni F, Cantini F, Lenzi P, Fornai F. Cell-Clearing Systems Bridging Repeat Expansion Proteotoxicity and Neuromuscular Junction Alterations in ALS and SBMA. Int J Mol Sci 2020; 21:ijms21114021. [PMID: 32512809 PMCID: PMC7312203 DOI: 10.3390/ijms21114021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 05/29/2020] [Accepted: 06/03/2020] [Indexed: 12/12/2022] Open
Abstract
The coordinated activities of autophagy and the ubiquitin proteasome system (UPS) are key to preventing the aggregation and toxicity of misfold-prone proteins which manifest in a number of neurodegenerative disorders. These include proteins which are encoded by genes containing nucleotide repeat expansions. In the present review we focus on the overlapping role of autophagy and the UPS in repeat expansion proteotoxicity associated with chromosome 9 open reading frame 72 (C9ORF72) and androgen receptor (AR) genes, which are implicated in two motor neuron disorders, amyotrophic lateral sclerosis (ALS) and spinal-bulbar muscular atrophy (SBMA), respectively. At baseline, both C9ORF72 and AR regulate autophagy, while their aberrantly-expanded isoforms may lead to a failure in both autophagy and the UPS, further promoting protein aggregation and toxicity within motor neurons and skeletal muscles. Besides proteotoxicity, autophagy and UPS alterations are also implicated in neuromuscular junction (NMJ) alterations, which occur early in both ALS and SBMA. In fact, autophagy and the UPS intermingle with endocytic/secretory pathways to regulate axonal homeostasis and neurotransmission by interacting with key proteins which operate at the NMJ, such as agrin, acetylcholine receptors (AChRs), and adrenergic beta2 receptors (B2-ARs). Thus, alterations of autophagy and the UPS configure as a common hallmark in both ALS and SBMA disease progression. The findings here discussed may contribute to disclosing overlapping molecular mechanisms which are associated with a failure in cell-clearing systems in ALS and SBMA.
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Affiliation(s)
- Fiona Limanaqi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via Roma 55, 56126 Pisa, Italy; (F.L.); (F.C.); (P.L.)
| | | | - Francesca Biagioni
- I.R.C.C.S. Neuromed, Via Atinense, 18, 86077 Pozzilli, Italy; (C.L.B.); (F.B.)
| | - Federica Cantini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via Roma 55, 56126 Pisa, Italy; (F.L.); (F.C.); (P.L.)
| | - Paola Lenzi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via Roma 55, 56126 Pisa, Italy; (F.L.); (F.C.); (P.L.)
| | - Francesco Fornai
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via Roma 55, 56126 Pisa, Italy; (F.L.); (F.C.); (P.L.)
- I.R.C.C.S. Neuromed, Via Atinense, 18, 86077 Pozzilli, Italy; (C.L.B.); (F.B.)
- Correspondence:
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172
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Ogasawara R, Jensen TE, Goodman CA, Hornberger TA. Resistance Exercise-Induced Hypertrophy: A Potential Role for Rapamycin-Insensitive mTOR. Exerc Sport Sci Rev 2020; 47:188-194. [PMID: 30870215 DOI: 10.1249/jes.0000000000000189] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The mechanistic target of rapamycin (mTOR) exerts both rapamycin-sensitive and rapamycin-insensitive signaling events, and the rapamycin-sensitive components of mTOR signaling have been widely implicated in the pathway through which resistance exercise induces skeletal muscle hypertrophy. This review explores the hypothesis that rapamycin-insensitive components of mTOR signaling also contribute to this highly important process.
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Affiliation(s)
- Riki Ogasawara
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan.,Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
| | - Thomas E Jensen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
| | - Craig A Goodman
- Institute of Health and Sport, Victoria University, Melbourne.,Australian Institute for Musculoskeletal Science, Victoria University, St. Albans, Victoria, Australia
| | - Troy A Hornberger
- Department of Comparative Biosciences, and.,School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI
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173
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Römermann D, Ansari N, Schultz-Moreira AR, Michael A, Marhenke S, Hardtke-Wolenski M, Longerich T, Manns MP, Wedemeyer H, Vogel A, Buitrago-Molina LE. Absence of Atg7 in the liver disturbed hepatic regeneration after liver injury. Liver Int 2020; 40:1225-1238. [PMID: 32141704 DOI: 10.1111/liv.14425] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 02/25/2020] [Accepted: 02/27/2020] [Indexed: 12/22/2022]
Abstract
BACKGROUND AND AIMS Autophagy is a critical process in cell survival and the maintenance of homeostasis. However, the implementation of therapeutic approaches based on autophagy mechanisms after liver damage is still challenging. METHODS We used a hepatospecific Atg7-deficient murine model to address this question. RESULTS We showed that the proliferation and regeneration capacity of Atg7-deficient hepatocytes was impaired. On the one hand, Atg7-deficient hepatocytes showed steady-state hyperproliferation. On the other hand, external triggers such as partial hepatectomy (PHx) or cell transplantation did not induce hepatocellular proliferation or liver repopulation. After PHx, hepatocyte proliferation was strongly decreased, accompanied by high mortality. This increase in mortality could be overcome by pharmacological mTOR inhibition. In accordance with hepatocyte hypoproliferation after damage, Atg7-deficient hepatocytes failed to repopulate the liver in a hepatic injury model. Atg7-deficient mice showed hepatic hypertrophy, transient cellular hypertrophy, and high transaminase levels followed by strong perisinusoidal/pericellular fibrosis with age. Their elevated modified hepatic activity index (mHAI) was almost exclusively due to apoptosis without any inflammation. These parameters were associated with variations in the triglyceride content and compromised lipid droplet formation after PHx. Mechanistically, we also observed a modulation of HGF, PAK4, NOTCH3 and YES1, which are proteins involved in cell cycle regulation. CONCLUSION We demonstrated the important role of autophagy in the regeneration capacity of hepatocytes. We showed the causative relationship between autophagy and triglycerides that is essential for promoting liver recovery. Finally, pharmacological mTOR inhibition overcame the impact of autophagy deficiency after liver damage and prevented mortality.
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Affiliation(s)
- Dorothee Römermann
- Department of Gastroenterology, Hepatology & Endocrinology, Hannover Medical School, Hannover, Germany
| | - Nadiea Ansari
- Department of Gastroenterology, Hepatology & Endocrinology, Hannover Medical School, Hannover, Germany
| | - Adriana Rita Schultz-Moreira
- Department of Gastroenterology and Hepatology, Essen University Hospital, University Duisburg-Essen, Essen, Germany
| | - Alina Michael
- Department of Gastroenterology, Hepatology & Endocrinology, Hannover Medical School, Hannover, Germany
| | - Silke Marhenke
- Department of Gastroenterology, Hepatology & Endocrinology, Hannover Medical School, Hannover, Germany
| | - Matthias Hardtke-Wolenski
- Department of Gastroenterology, Hepatology & Endocrinology, Hannover Medical School, Hannover, Germany.,Department of Gastroenterology and Hepatology, Essen University Hospital, University Duisburg-Essen, Essen, Germany
| | - Thomas Longerich
- Institute of Pathology, University of Heidelberg, Heidelberg, Germany
| | - Michael P Manns
- Department of Gastroenterology, Hepatology & Endocrinology, Hannover Medical School, Hannover, Germany
| | - Heiner Wedemeyer
- Department of Gastroenterology, Hepatology & Endocrinology, Hannover Medical School, Hannover, Germany.,Department of Gastroenterology and Hepatology, Essen University Hospital, University Duisburg-Essen, Essen, Germany
| | - Arndt Vogel
- Department of Gastroenterology, Hepatology & Endocrinology, Hannover Medical School, Hannover, Germany
| | - Laura Elisa Buitrago-Molina
- Department of Gastroenterology, Hepatology & Endocrinology, Hannover Medical School, Hannover, Germany.,Department of Gastroenterology and Hepatology, Essen University Hospital, University Duisburg-Essen, Essen, Germany
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174
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Promiscuous Roles of Autophagy and Proteasome in Neurodegenerative Proteinopathies. Int J Mol Sci 2020; 21:ijms21083028. [PMID: 32344772 PMCID: PMC7215558 DOI: 10.3390/ijms21083028] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 12/12/2022] Open
Abstract
Alterations in autophagy and the ubiquitin proteasome system (UPS) are commonly implicated in protein aggregation and toxicity which manifest in a number of neurological disorders. In fact, both UPS and autophagy alterations are bound to the aggregation, spreading and toxicity of the so-called prionoid proteins, including alpha synuclein (α-syn), amyloid-beta (Aβ), tau, huntingtin, superoxide dismutase-1 (SOD-1), TAR-DNA-binding protein of 43 kDa (TDP-43) and fused in sarcoma (FUS). Recent biochemical and morphological studies add to this scenario, focusing on the coordinated, either synergistic or compensatory, interplay that occurs between autophagy and the UPS. In fact, a number of biochemical pathways such as mammalian target of rapamycin (mTOR), transcription factor EB (TFEB), Bcl2-associated athanogene 1/3 (BAG3/1) and glycogen synthase kinase beta (GSk3β), which are widely explored as potential targets in neurodegenerative proteinopathies, operate at the crossroad between autophagy and UPS. These biochemical steps are key in orchestrating the specificity and magnitude of the two degradation systems for effective protein homeostasis, while intermingling with intracellular secretory/trafficking and inflammatory pathways. The findings discussed in the present manuscript are supposed to add novel viewpoints which may further enrich our insight on the complex interactions occurring between cell-clearing systems, protein misfolding and propagation. Discovering novel mechanisms enabling a cross-talk between the UPS and autophagy is expected to provide novel potential molecular targets in proteinopathies.
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175
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Yamaguchi I, Yoshimura SH, Katoh H. High cell density increases glioblastoma cell viability under glucose deprivation via degradation of the cystine/glutamate transporter xCT (SLC7A11). J Biol Chem 2020; 295:6936-6945. [PMID: 32265299 DOI: 10.1074/jbc.ra119.012213] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/25/2020] [Indexed: 12/12/2022] Open
Abstract
The cystine/glutamate transporter system xc - consists of the light-chain subunit xCT (SLC7A11) and the heavy-chain subunit CD98 (4F2hc or SLC3A2) and exchanges extracellular cystine for intracellular glutamate at the plasma membrane. The imported cystine is reduced to cysteine and used for synthesis of GSH, one of the most important antioxidants in cancer cells. Because cancer cells have increased levels of reactive oxygen species, xCT, responsible for cystine-glutamate exchange, is overexpressed in many cancers, including glioblastoma. However, under glucose-limited conditions, xCT overexpression induces reactive oxygen species accumulation and cell death. Here we report that cell survival under glucose deprivation depends on cell density. We found that high cell density (HD) down-regulates xCT levels and increases cell viability under glucose deprivation. We also found that growth of glioblastoma cells at HD inactivates mTOR and that treatment of cells grown at low density with the mTOR inhibitor Torin 1 down-regulates xCT and inhibits glucose deprivation-induced cell death. The lysosome inhibitor bafilomycin A1 suppressed xCT down-regulation in HD-cultured glioblastoma cells and in Torin 1-treated cells grown at low density. Additionally, bafilomycin A1 exposure or ectopic xCT expression restored glucose deprivation-induced cell death at HD. These results suggest that HD inactivates mTOR and promotes lysosomal degradation of xCT, leading to improved glioblastoma cell viability under glucose-limited conditions. Our findings provide evidence that control of xCT protein expression via lysosomal degradation is an important mechanism for metabolic adaptation in glioblastoma cells.
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Affiliation(s)
- Itsuki Yamaguchi
- Laboratory of Molecular Neurobiology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shige H Yoshimura
- Laboratory of Plasma Membrane and Nuclear Signaling, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hironori Katoh
- Laboratory of Molecular Neurobiology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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176
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Zhang B, Zhong X, Sauane M, Zhao Y, Zheng ZL. Modulation of the Pol II CTD Phosphorylation Code by Rac1 and Cdc42 Small GTPases in Cultured Human Cancer Cells and Its Implication for Developing a Synthetic-Lethal Cancer Therapy. Cells 2020; 9:cells9030621. [PMID: 32143485 PMCID: PMC7140432 DOI: 10.3390/cells9030621] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/25/2020] [Accepted: 03/02/2020] [Indexed: 12/29/2022] Open
Abstract
Rho GTPases, including Rho, Cdc42, Rac and ROP subfamilies, are key signaling molecules in RNA polymerase II (Pol II) transcriptional control. Our prior work has shown that plant ROP and yeast Cdc42 GTPases similarly modulate Ser2 and Ser5 phosphorylation status of the C-terminal domain (CTD) of the Pol II largest subunit by regulating CTD phosphatase degradation. Here, we present genetic and pharmacological evidence showing that Cdc42 and Rac1 GTPase signaling modulates a similar CTD Ser2 and Ser5 phosphorylation code in cultured human cancer cells. While siRNA knockdown of Cdc42 and Rac1, respectively, in HeLa cells increased the level of CTD Ser phosphatases RPAP2 and FCP1, they both decreased the level of CTD kinases CDK7 and CDK13. In addition, the protein degradation inhibitor MG132 reversed the effect of THZ1, a CDK7 inhibitor which could decrease the cell number and amount of CDK7 and CDK13, accompanied by a reduction in the level of CTD Ser2 and Ser5 phosphorylation and DOCK4 and DOCK9 (the activators for Rac1 and Cdc42, respectively). Conversely, treatments of Torin1 or serum deprivation, both of which promote protein degradation, could enhance the effect of THZ1, indicating the involvement of protein degradation in controlling CDK7 and CDK13. Our results support an evolutionarily conserved signaling shortcut model linking Rho GTPases to Pol II transcription across three kingdoms, Fungi, Plantae and Animalia, and could lead to the development of a potential synthetic-lethal strategy in controlling cancer cell proliferation or death.
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Affiliation(s)
- Bo Zhang
- Department of Biological Sciences, Lehman College, City University of New York, Bronx, NY 10468, USA
- Department of Biology, Wenzhou-Kean University, Wenzhou, Zhejiang 325060, China
| | - Xuelin Zhong
- Department of Biological Sciences, Lehman College, City University of New York, Bronx, NY 10468, USA
- Biology PhD Program, Graduate School and University Center, City University of New York, New York, NY 10016, USA
| | - Moira Sauane
- Department of Biological Sciences, Lehman College, City University of New York, Bronx, NY 10468, USA
- Biology PhD Program, Graduate School and University Center, City University of New York, New York, NY 10016, USA
| | - Yihong Zhao
- Center of Alcohol and Substance Use Studies and Department of Applied Psychology, Graduate School of Applied and Professional Psychology, Rutgers University, Piscataway, NJ 08854, USA
| | - Zhi-Liang Zheng
- Department of Biological Sciences, Lehman College, City University of New York, Bronx, NY 10468, USA
- Correspondence:
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177
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Abstract
PURPOSE OF REVIEW Skeletal muscle wasting during critical illness is the result of disturbed metabolism. No proven effective interventions targeting skeletal muscle mass and function during critical illness currently exist. This review summarizes recent advances regarding the complexity of metabolic factors involved and the challenge of establishing the clinical effects of metabolic interventions targeting the muscle. RECENT FINDINGS Although the catabolic state is limited to the acute phase of critical illness, its subsequent impact on muscle mass and function persists long after ICU discharge. Immobilization, inflammation and disturbed muscle energy and nutrient metabolism are key drivers of muscle protein loss. Current research focuses on the effects of enhanced protein provision, specific substrate delivery and physical exercise. Whilst some interventions have been successful at improving muscle mass, these effects do not always carry over into muscle function or strength. SUMMARY Increased understanding of metabolic derangements during critical illness provides new potential targets for treatment. The potential of dietary protein to attenuate the muscle protein catabolic state has yet to be established in clinical trials. Basic research should focus on ways to further improve the anabolic potential of nutrition by unravelling mechanisms that regulate anabolic and catabolic pathways and energy metabolism.
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Affiliation(s)
- Robert J.J. van Gassel
- Department of Intensive Care Medicine
- Department of Surgery, Maastricht University Medical Centre and NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, The Netherlands
| | | | - Marcel C.G. van de Poll
- Department of Intensive Care Medicine
- Department of Surgery, Maastricht University Medical Centre and NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, The Netherlands
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178
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mTOR-Related Cell-Clearing Systems in Epileptic Seizures, an Update. Int J Mol Sci 2020; 21:ijms21051642. [PMID: 32121250 PMCID: PMC7084443 DOI: 10.3390/ijms21051642] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/25/2020] [Accepted: 02/26/2020] [Indexed: 02/06/2023] Open
Abstract
Recent evidence suggests that autophagy impairment is implicated in the epileptogenic mechanisms downstream of mTOR hyperactivation. This holds true for a variety of genetic and acquired epileptic syndromes besides malformations of cortical development which are classically known as mTORopathies. Autophagy suppression is sufficient to induce epilepsy in experimental models, while rescuing autophagy prevents epileptogenesis, improves behavioral alterations, and provides neuroprotection in seizure-induced neuronal damage. The implication of autophagy in epileptogenesis and maturation phenomena related to seizure activity is supported by evidence indicating that autophagy is involved in the molecular mechanisms which are implicated in epilepsy. In general, mTOR-dependent autophagy regulates the proliferation and migration of inter-/neuronal cortical progenitors, synapse development, vesicular release, synaptic plasticity, and importantly, synaptic clustering of GABAA receptors and subsequent excitatory/inhibitory balance in the brain. Similar to autophagy, the ubiquitin–proteasome system is regulated downstream of mTOR, and it is implicated in epileptogenesis. Thus, mTOR-dependent cell-clearing systems are now taking center stage in the field of epilepsy. In the present review, we discuss such evidence in a variety of seizure-related disorders and models. This is expected to provide a deeper insight into the molecular mechanisms underlying seizure activity.
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179
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Autophagy Inhibition Potentiates the Anticancer Effects of a Bendamustine Derivative NL-101 in Acute T Lymphocytic Leukemia. BIOMED RESEARCH INTERNATIONAL 2020; 2020:1520651. [PMID: 32149078 PMCID: PMC7042524 DOI: 10.1155/2020/1520651] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 12/28/2019] [Accepted: 01/23/2020] [Indexed: 12/16/2022]
Abstract
Acute T lymphocytic leukemia (T-ALL) is an aggressive hematologic resulting from the malignant transformation of T-cell progenitors. Drug resistance and relapse are major difficulties in the treatment of T-ALL. Here, we report the antitumor potency of NL-101, a compound that combines the nitrogen mustard group of bendamustine with the hydroxamic acid group of vorinostat. We found NL-101 exhibited efficient antiproliferative activity in T-ALL cell lines (IC50 1.59–1.89 μM), accompanied by cell cycle arrest and apoptosis, as evidenced by the increased expression of Cyclin E1, CDK2, and CDK4 proteins and cleavage of PARP. In addition, this bendamustine-derived drug showed both a HDACi effect as demonstrated by histone hyperacetylation and p21 transcription and a DNA-damaging effect as shown by an increase in γ-H2AX. Intriguingly, we found that NL-101-induced autophagy in T-ALL cells through inhibiting Akt-mTOR signaling pathway, as indicated by an increase in LC3-I to LC3-II conversion and decrease of p62. Furthermore, inhibition of autophagy by 3-methyladenine increased apoptotic cell death by NL-101, suggesting a prosurvival role of autophagy. In summary, our finding provides rationale for investigation of NL-101 as a DNA/HDAC dual targeting drug in T-ALL, either as a single agent or in combination with autophagy inhibitors.
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180
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Hassanpour M, Hajihassani F, Hiradfar A, Aghamohammadzadeh N, Rahbarghazi R, Safaie N, Nouri M, Panahi Y. Real-state of autophagy signaling pathway in neurodegenerative disease; focus on multiple sclerosis. JOURNAL OF INFLAMMATION-LONDON 2020; 17:6. [PMID: 32082082 PMCID: PMC7014934 DOI: 10.1186/s12950-020-0237-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 01/27/2020] [Indexed: 12/12/2022]
Abstract
The occurrence of neurodegenerative disease is increasingly raised. From physiopathological aspect, the emergence of auto-reactive antibodies against the nervous system antigens contributes to de-myelination in Multiple sclerosis (MS). These features cause the nervous system dysfunction. The follow-up of molecular alterations could give us a real-state vision about intracellular status during pathological circumstances. In this review, we focus on the autophagic response during MS progression and further understand the relationship between autophagy and MS and its modulatory effect on the MS evolution. The authors reviewed studies published on the autophagy status in neurodegenerative disease and on the autophagy modulation in MS prognosis, diagnosis, and possible therapies. The inevitable role of autophagy was shown in the early-stage progression of MS. Due to critical role of autophagy in different stage of cell activity in nervous system, the distinct role of autophagy should not be neglected in the development, pathogenesis, and treatment of MS.
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Affiliation(s)
- Mehdi Hassanpour
- 1Department of Clinical Biochemistry and Laboratory Medicine, Tabriz University of Medical Sciences, 5166614756, Imam Reza St., Golgasht St, Tabriz, Iran.,2Stem Cell And Regenerative Medicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran.,3Clinical Pharmacy Department, Faculty of Pharmacy, Baqiyatallah University of Medical Sciences, Tehran, 1435916471 Iran
| | - Fateme Hajihassani
- 4Department of Health Management, School of Management and Medical informatics, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Amirataollah Hiradfar
- 5Pediatric Health Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | - Reza Rahbarghazi
- 7Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.,8Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Nasser Safaie
- 9Cardiovascular Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mohammad Nouri
- 1Department of Clinical Biochemistry and Laboratory Medicine, Tabriz University of Medical Sciences, 5166614756, Imam Reza St., Golgasht St, Tabriz, Iran.,2Stem Cell And Regenerative Medicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Yunes Panahi
- 3Clinical Pharmacy Department, Faculty of Pharmacy, Baqiyatallah University of Medical Sciences, Tehran, 1435916471 Iran
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181
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mTOR Regulation of Metabolism in Hematologic Malignancies. Cells 2020; 9:cells9020404. [PMID: 32053876 PMCID: PMC7072383 DOI: 10.3390/cells9020404] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/02/2020] [Accepted: 02/07/2020] [Indexed: 02/06/2023] Open
Abstract
Neoplastic cells rewire their metabolism, acquiring a selective advantage over normal cells and a protection from therapeutic agents. The mammalian Target of Rapamycin (mTOR) is a serine/threonine kinase involved in a variety of cellular activities, including the control of metabolic processes. mTOR is hyperactivated in a large number of tumor types, and among them, in many hematologic malignancies. In this article, we summarized the evidence from the literature that describes a central role for mTOR in the acquisition of new metabolic phenotypes for different hematologic malignancies, in concert with other metabolic modulators (AMPK, HIF1α) and microenvironmental stimuli, and shows how these features can be targeted for therapeutic purposes.
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182
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Abstract
Autophagy in the skeletal muscle increases under catabolic conditions resulting in muscle atrophy. This study investigated the effect of inhibition of mechanistic target of rapamycin (mTOR) on autophagy in chick skeletal muscle. We examined the effects of Torin1, an mTOR inhibitor, on autophagy. Chick myotubes were incubated with Torin1 (100 nM) for 3 h. It was observed that Torin1 inhibited the phosphorylation of AKT (Ser473), p70 ribosomal S6 kinase 1 (S6K1, Thr389), S6 ribosomal protein (Ser235/236), and eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1, Thr37/46), which are used for measurement of mTOR activity. Torin1 significantly (P< 0.01) increased the LC3-II/LC3-I ratio, an index for autophagosome formation, while it did not influence the expression of autophagy-related genes (LC3B, GABARAPL1, and ATG12). In addition, Torin1 increased atrogin-1/MAFbx (a muscle-specific ubiquitin ligase) mRNA expression. Fasting for 24 h inhibited the phosphorylation of AKT (Ser473), S6K1 (Ther389), S6 ribosomal protein (Ser235/236), and 4E-BP1 (Thr37/46) in chick skeletal muscle and significantly (P<0.01) increased the LC3-II/LC3-I ratio. Fasting also increased GABARAPL1 and atrogin-1/MAFbx mRNA expression but not LC3B or ATG12 mRNA expression. These results indicate that mTOR signaling regulates autophagy and the ubiquitin-proteasome proteolytic pathway in chick skeletal muscle.
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183
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Beese CJ, Brynjólfsdóttir SH, Frankel LB. Selective Autophagy of the Protein Homeostasis Machinery: Ribophagy, Proteaphagy and ER-Phagy. Front Cell Dev Biol 2020; 7:373. [PMID: 32039200 PMCID: PMC6985035 DOI: 10.3389/fcell.2019.00373] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 12/16/2019] [Indexed: 01/06/2023] Open
Abstract
The eukaryotic cell has developed intricate machineries that monitor and maintain proteome homeostasis in order to ensure cellular functionality. This involves the carefully coordinated balance between protein synthesis and degradation pathways, which are dynamically regulated in order to meet the constantly changing demands of the cell. Ribosomes, together with the endoplasmic reticulum (ER), are the key drivers of protein synthesis, folding, maturation and sorting, while the proteasome plays a pivotal role in terminating the existence of thousands of proteins that are misfolded, damaged or otherwise obsolete. The synthesis, structure and function of these dedicated machines has been studied for decades, however, much less is understood about the mechanisms that control and execute their own turnover. Autophagy, an evolutionarily conserved catabolic pathway, mediates degradation of a large variety of cytosolic substrates, ranging from single proteins to entire organelles or multi-subunit macromolecular complexes. In this review, we focus on selective autophagy of three key components of the protein homeostasis machinery: ribosomes, ER and proteasomes, through the selective autophagy pathways of ribophagy, ER-phagy, and proteaphagy. We discuss newly discovered mechanisms for the selective clearance of these substrates, which are often stress-dependent and involve specialized signals for cargo recognition by a growing number of receptors. We further discuss the interplay between these pathways and their biological impact on key aspects of proteome homeostasis and cellular function in health and disease.
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Affiliation(s)
- Carsten J Beese
- Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark.,Danish Cancer Society Research Center, Copenhagen, Denmark
| | | | - Lisa B Frankel
- Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark.,Danish Cancer Society Research Center, Copenhagen, Denmark
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184
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Jayaraj GG, Hipp MS, Hartl FU. Functional Modules of the Proteostasis Network. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a033951. [PMID: 30833457 DOI: 10.1101/cshperspect.a033951] [Citation(s) in RCA: 109] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cells invest in an extensive network of factors to maintain protein homeostasis (proteostasis) and prevent the accumulation of potentially toxic protein aggregates. This proteostasis network (PN) comprises the machineries for the biogenesis, folding, conformational maintenance, and degradation of proteins with molecular chaperones as central coordinators. Here, we review recent progress in understanding the modular architecture of the PN in mammalian cells and how it is modified during cell differentiation. We discuss the capacity and limitations of the PN in maintaining proteome integrity in the face of proteotoxic stresses, such as aggregate formation in neurodegenerative diseases. Finally, we outline various pharmacological interventions to ameliorate proteostasis imbalance.
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Affiliation(s)
- Gopal G Jayaraj
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Mark S Hipp
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - F Ulrich Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
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185
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Finley D, Prado MA. The Proteasome and Its Network: Engineering for Adaptability. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a033985. [PMID: 30833452 DOI: 10.1101/cshperspect.a033985] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The proteasome, the most complex protease known, degrades proteins that have been conjugated to ubiquitin. It faces the unique challenge of acting enzymatically on hundreds and perhaps thousands of structurally diverse substrates, mechanically unfolding them from their native state and translocating them vectorially from one specialized compartment of the enzyme to another. Moreover, substrates are modified by ubiquitin in myriad configurations of chains. The many unusual design features of the proteasome may have evolved in part to endow this enzyme with a robust ability to process substrates regardless of their identity. The proteasome plays a major role in preserving protein homeostasis in the cell, which requires adaptation to a wide variety of stress conditions. Modulation of proteasome function is achieved through a large network of proteins that interact with it dynamically, modify it enzymatically, or fine-tune its levels. The resulting adaptability of the proteasome, which is unique among proteases, enables cells to control the output of the ubiquitin-proteasome pathway on a global scale.
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Affiliation(s)
- Daniel Finley
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
| | - Miguel A Prado
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
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186
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Kwon D, Kim SM, Correia MA. Cytochrome P450 endoplasmic reticulum-associated degradation (ERAD): therapeutic and pathophysiological implications. Acta Pharm Sin B 2020; 10:42-60. [PMID: 31993306 PMCID: PMC6976991 DOI: 10.1016/j.apsb.2019.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 10/30/2019] [Accepted: 10/31/2019] [Indexed: 02/07/2023] Open
Abstract
The hepatic endoplasmic reticulum (ER)-anchored cytochromes P450 (P450s) are mixed-function oxidases engaged in the biotransformation of physiologically relevant endobiotics as well as of myriad xenobiotics of therapeutic and environmental relevance. P450 ER-content and hence function is regulated by their coordinated hemoprotein syntheses and proteolytic turnover. Such P450 proteolytic turnover occurs through a process known as ER-associated degradation (ERAD) that involves ubiquitin-dependent proteasomal degradation (UPD) and/or autophagic-lysosomal degradation (ALD). Herein, on the basis of available literature reports and our own recent findings of in vitro as well as in vivo experimental studies, we discuss the therapeutic and pathophysiological implications of altered P450 ERAD and its plausible clinical relevance. We specifically (i) describe the P450 ERAD-machinery and how it may be repurposed for the generation of antigenic P450 peptides involved in P450 autoantibody pathogenesis in drug-induced acute hypersensitivity reactions and liver injury, or viral hepatitis; (ii) discuss the relevance of accelerated or disrupted P450-ERAD to the pharmacological and/or toxicological effects of clinically relevant P450 drug substrates; and (iii) detail the pathophysiological consequences of disrupted P450 ERAD, contributing to non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) under certain synergistic cellular conditions.
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Key Words
- 3MA, 3-methyladenine
- AAA, ATPases associated with various cellular activities
- ACC1, acetyl-CoA carboxylase 1
- ACC2, acetyl-CoA carboxylase 2
- ACHE, acetylcholinesterase
- ACOX1, acyl-CoA oxidase 1
- ALD, autophagic-lysosomal degradation
- AMPK1
- AP-1, activator protein 1
- ASK1, apoptosis signal-regulating kinase
- ATF2, activating transcription factor 2
- AdipoR1, gene of adiponectin receptor 1
- Atg14, autophagy-related 14
- CBZ, carbamazepine
- CHIP E3 ubiquitin ligase
- CHIP, carboxy-terminus of Hsc70-interacting protein
- Cytochromes P450
- Endoplasmic reticulum-associated degradation
- FOXO, forkhead box O
- Fas, fatty acid synthase
- GAPDH, glyceraldehyde 3-phosphate dehydrogenase
- INH, isoniazid
- IRS1, insulin receptor substrate 1
- Il-1β, interleukin 1 β
- Il-6, interleukin 6
- Insig1, insulin-induced gene 1
- JNK1
- Lpl, lipoprotein lipase
- Mcp1, chemokine (C–C motif) ligand 1
- Non-alcoholic fatty liver disease
- Non-alcoholic steatohepatitis
- Pgc1, peroxisome proliferator-activated receptor coactivator 1
- SREBP1c, sterol regulatory element binding transcription factor 1c
- Scd1, stearoyl-coenzyme A desaturase
- Tnf, tumor necrosis factor
- UPD, ubiquitin (Ub)-dependent proteasomal degradation
- Ub, ubiquitin
- gp78/AMFR E3 ubiquitin ligase
- gp78/AMFR, autocrine motility factor receptor
- shRNAi, shRNA interference
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187
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Chen MJ, Fu Z, Jiang SG, Wang XQ, Yan HC, Gao CQ. Targeted disruption of TORC1 retards young squab growth by inhibiting the synthesis of crop milk protein in breeding pigeon (Columba livia). Poult Sci 2020; 99:416-422. [PMID: 32416826 PMCID: PMC7587900 DOI: 10.3382/ps/pez513] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 08/22/2019] [Indexed: 12/18/2022] Open
Abstract
This study was conducted to explore the regulatory role of the target of rapamycin complex 1 (TORC1) signaling pathway in crop milk synthesis in breeding pigeons (Columba livia). Three groups of breeding pigeons in the lactation period (n = 30 pairs/group) were respectively injected with rapamycin (RAPA, a specific inhibitor of the target of rapamycin complex) at doses of 0 (vehicle, control), 0.6, or 1.2 mg/kg body weight (BW)/day via the wing vein for 7 days. The average daily feed intake (ADFI) and BW of the breeding pigeons and the BW of young squabs were respectively recorded throughout the experimental period. The breeding pigeons were sacrificed to collect their crop tissues, crop milk, and serum on the eighth day of the experiment. The results showed that neither 0.6 nor 1.2 mg/kg BW RAPA injection affected BW loss or ADFI in breeding pigeons (P > 0.05), while crop thickness and crop relative weight were significantly decreased (P < 0.05) in the 1.2 mg/kg BW rapamycin-injected group. Simultaneously, RAPA (especially at 1.2 mg/kg BW) decreased the crude protein, αs1-casein, αs2-casein, β-casein, and amino acid contents (Asp, Thr, Ser, Glu, Gly, Ala, Cys, Val, Met, Ile, Leu, Tyr, Lys, His, Arg, and Pro) of crop milk (P < 0.05) and the concentrations of albumin, total protein, and uric acid in the serum of breeding pigeons (P < 0.05). Additionally, the expression of TORC1 pathway-related proteins (TORC1, S6K1, S6, 4EBP1, and eIF4E) was downregulated in the crop tissues of breeding pigeons by 0.6 or 1.2 mg/kg BW/day RAPA injection (P < 0.05). Accordingly, the average daily gain (ADG) of young squabs declined, and the mortality rate increased significantly (P < 0.05). Together, the results showed that RAPA reduced protein and amino acid levels in the crop milk of breeding pigeons and retarded young squab growth, suggesting a crucial role of TORC1 in crop milk synthesis in breeding pigeons.
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Affiliation(s)
- M J Chen
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition Control/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong 510642, China
| | - Z Fu
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition Control/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong 510642, China
| | - S G Jiang
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition Control/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong 510642, China
| | - X Q Wang
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition Control/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong 510642, China
| | - H C Yan
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition Control/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong 510642, China
| | - C Q Gao
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition Control/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong 510642, China.
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188
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Sharma S, Gangenahalli GU, Singh U. Regulation of Hematopoietic Activity Involving New Interacting Partners (RRAGC & PSMC2, CKAP4 & MANF and CTR9 & CNTNAP2). Cell 2020. [DOI: 10.4236/cellbio.2020.93007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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189
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Lessons Learned from Proteasome Inhibitors, the Paradigm for Targeting Protein Homeostasis in Cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1243:147-162. [PMID: 32297217 DOI: 10.1007/978-3-030-40204-4_10] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Targeting aberrant protein homeostasis (proteostasis) in cancer is an attractive therapeutic strategy. However, this approach has thus far proven difficult to bring to clinical practice, with one major exception: proteasome inhibition. These small molecules have dramatically transformed outcomes for patients with the blood cancer multiple myeloma. However, these agents have failed to make an impact in more common solid tumors. Major questions remain about whether this therapeutic strategy can be extended to benefit even more patients. Here we discuss the role of the proteasome in normal and tumor cells, the basic, preclinical, and clinical development of proteasome inhibitors, and mechanisms proposed to govern both intrinsic and acquired resistance to these drugs. Years of study of both the mechanism of action and modes of resistance to proteasome inhibitors reveal these processes to be surprisingly complex. Here, we attempt to draw lessons from experience with proteasome inhibitors that may be relevant for other compounds targeting proteostasis in cancer, as well as extending the reach of proteasome inhibitors beyond blood cancers.
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190
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Makanae Y, Ato S, Kido K, Fujita S. Dietary Aronia melanocarpa extract enhances mTORC1 signaling, but has no effect on protein synthesis and protein breakdown-related signaling, in response to resistance exercise in rat skeletal muscle. J Int Soc Sports Nutr 2019; 16:60. [PMID: 31829236 PMCID: PMC6907222 DOI: 10.1186/s12970-019-0328-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 11/29/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ursolic acid altered muscle protein metabolism in normal and resting conditions after acute resistance exercise, suggesting that eating fruits rich in ursolic acid could enhance muscle protein synthesis and decrease muscle degradation. Aronia melanocarpa, a member of the family Rosaceae and native to North America and Eastern Canada, is rich in ursolic acid. In this study, we examined the effects of A. melanocarpa extract (AME) supplementation on the mTORC1 signaling pathway and muscle degradation-related factors in rats, both alone and in combination with resistance exercise. METHODS Male Sprague-Dawley rats were divided into AME and normal chow (NOR) groups. AME group was fed chow providing a dose of 3 g/kg of AME and 115 mg/kg of ursolic acid for 7 days, whereas NOR rats were fed normal powder chow. The right gastrocnemius muscle of each animal was isometrically exercised (5 sets of ten 3-s contractions, with a 7-s interval between contractions and 3-min rest intervals between sets), while the left gastrocnemius muscle served as an internal control. Western blotting and real-time polymerase chain reaction were used to assess expression of factors involved in the mTORC1 signaling pathway and muscle degradation. RESULTS At 1 h after resistance exercise, phosphorylation of ERK1/2 was significantly increased by AME consumption. At 6 h after resistance exercise, AME consumption significantly increased the phosphorylation of Akt, p70S6K, rpS6, and AMPK. It also increased MAFbx expression. Furthermore, AME significantly increased the phosphorylation of p70S6K and rpS6 in response to resistance exercise. However, AME did not increase muscle protein synthesis (MPS) after resistance exercise. AME did not affect the expression of any of the mediators of protein degradation, with the exception of MAFbx. CONCLUSIONS Dietary AME enhanced mTORC1 activation in response to resistance exercise without increasing MPS. Moreover, it neither accelerated muscle protein degradation nor otherwise negatively affected protein metabolism. Further study is needed to clarify the effect of the combination of AME and chronic resistance training on muscle hypertrophy.
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Affiliation(s)
- Yuhei Makanae
- Department of Physical Education, National Defense Academy, Yokosuka, Kanagawa Japan
- Ritsumeikan Global Innovation Research Organization, Ritsumeikan University, Kusatsu, Shiga Japan
- Faculty of Sports and Health Science, Ritsumeikan University, Kusatsu, Shiga Japan
| | - Satoru Ato
- Faculty of Sports and Health Science, Ritsumeikan University, Kusatsu, Shiga Japan
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Kohei Kido
- Faculty of Sports and Health Science, Ritsumeikan University, Kusatsu, Shiga Japan
- Laboratory of Sports and Exercise Medicine, Graduate School of Human and Envionmental Studies, Kyoto University, Kyoto, Japan
| | - Satoshi Fujita
- Ritsumeikan Global Innovation Research Organization, Ritsumeikan University, Kusatsu, Shiga Japan
- Faculty of Sports and Health Science, Ritsumeikan University, Kusatsu, Shiga Japan
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191
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Cassidy KC, Lahr RM, Kaminsky JC, Mack S, Fonseca BD, Das SR, Berman AJ, Durrant JD. Capturing the Mechanism Underlying TOP mRNA Binding to LARP1. Structure 2019; 27:1771-1781.e5. [PMID: 31676287 PMCID: PMC7269035 DOI: 10.1016/j.str.2019.10.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 08/06/2019] [Accepted: 10/10/2019] [Indexed: 12/20/2022]
Abstract
The RNA-binding protein La-related protein 1 (LARP1) plays a central role in ribosome biosynthesis. Its C-terminal DM15 region binds the 7-methylguanosine (m7G) cap and 5' terminal oligopyrimidine (TOP) motif characteristic of transcripts encoding ribosomal proteins and translation factors. Under the control of mammalian target of rapamycin complex 1 (mTORC1), LARP1 regulates translation of these transcripts. Characterizing the dynamics of DM15-TOP recognition is essential to understanding this fundamental biological process. We use molecular dynamics simulations, biophysical assays, and X-ray crystallography to reveal the mechanism of DM15 binding to TOP transcripts. Residues C-terminal to the m7G-binding site play important roles in cap recognition. Furthermore, we show that the unusually static pocket that recognizes the +1 cytosine characteristic of TOP transcripts drives binding specificity. Finally, we demonstrate that the DM15 pockets involved in TOP-specific m7GpppC-motif recognition are likely druggable. Collectively, these studies suggest unique opportunities for further pharmacological development.
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Affiliation(s)
- Kevin C Cassidy
- Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, USA
| | - Roni M Lahr
- Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, USA
| | - Jesse C Kaminsky
- Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, USA
| | - Stephanie Mack
- Department of Chemistry and Center for Nucleic Acids Science & Technology, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA
| | - Bruno D Fonseca
- Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, K1H 8L1 ON, Canada
| | - Subha R Das
- Department of Chemistry and Center for Nucleic Acids Science & Technology, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA
| | - Andrea J Berman
- Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, USA.
| | - Jacob D Durrant
- Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, USA.
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192
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Stead ER, Castillo-Quan JI, Miguel VEM, Lujan C, Ketteler R, Kinghorn KJ, Bjedov I. Agephagy - Adapting Autophagy for Health During Aging. Front Cell Dev Biol 2019; 7:308. [PMID: 31850344 PMCID: PMC6892982 DOI: 10.3389/fcell.2019.00308] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 11/12/2019] [Indexed: 12/11/2022] Open
Abstract
Autophagy is a major cellular recycling process that delivers cellular material and entire organelles to lysosomes for degradation, in a selective or non-selective manner. This process is essential for the maintenance of cellular energy levels, components, and metabolites, as well as the elimination of cellular molecular damage, thereby playing an important role in numerous cellular activities. An important function of autophagy is to enable survival under starvation conditions and other stresses. The majority of factors implicated in aging are modifiable through the process of autophagy, including the accumulation of oxidative damage and loss of proteostasis, genomic instability and epigenetic alteration. These primary causes of damage could lead to mitochondrial dysfunction, deregulation of nutrient sensing pathways and cellular senescence, finally causing a variety of aging phenotypes. Remarkably, advances in the biology of aging have revealed that aging is a malleable process: a mild decrease in signaling through nutrient-sensing pathways can improve health and extend lifespan in all model organisms tested. Consequently, autophagy is implicated in both aging and age-related disease. Enhancement of the autophagy process is a common characteristic of all principal, evolutionary conserved anti-aging interventions, including dietary restriction, as well as inhibition of target of rapamycin (TOR) and insulin/IGF-1 signaling (IIS). As an emerging and critical process in aging, this review will highlight how autophagy can be modulated for health improvement.
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Affiliation(s)
- Eleanor R Stead
- UCL Cancer Institute, University College London, London, United Kingdom
| | - Jorge I Castillo-Quan
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Boston, MA, United States.,Department of Genetics, Harvard Medical School, Boston, MA, United States
| | | | - Celia Lujan
- UCL Cancer Institute, University College London, London, United Kingdom
| | - Robin Ketteler
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Kerri J Kinghorn
- Institute of Healthy Ageing, University College London, London, United Kingdom.,Department of Genetics, Evolution and Environment, University College London, London, United Kingdom.,Institute of Neurology, University College London, London, United Kingdom
| | - Ivana Bjedov
- UCL Cancer Institute, University College London, London, United Kingdom
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193
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Adegoke OAJ, Beatty BE, Kimball SR, Wing SS. Interactions of the super complexes: When mTORC1 meets the proteasome. Int J Biochem Cell Biol 2019; 117:105638. [PMID: 31678320 DOI: 10.1016/j.biocel.2019.105638] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 10/18/2019] [Accepted: 10/20/2019] [Indexed: 12/30/2022]
Abstract
Homeostatic regulation of energy and metabolic status requires that anabolic and catabolic signaling pathways be precisely regulated and coordinated. Mammalian/mechanistic target of rapamycin complex 1 (mTORC1) is a mega protein complex that promotes energy-consuming anabolic processes of protein and nucleic acid synthesis as well lipogenesis in times of energy and nutrient abundance. However, it is best characterized as the regulator of steps leading to protein synthesis. The ubiquitin-proteasome proteolytic system (UPS) is a major intracellular proteolytic system whose activity is increased during periods of nutrient scarcity and in muscle wasting conditions such as cachexia. Recent studies have examined the impact of mTORC1 on levels and functions of the 26S proteasome, the mega protease complex of the UPS. Here we first briefly review current understanding of the regulation of mTORC1, the UPS, and the 26S proteasome complex. We then review evidence of the effect of each complex on the abundance and functions of the other. Given the fact that drugs that inhibit either complex are either in clinical trials or are approved for treatment of cancer, a muscle wasting condition, we identify studying the effect of combinatory mTORC1-proteasome inhibition on skeletal muscle mass and health as a critical area requiring investigation.
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Affiliation(s)
- Olasunkanmi A J Adegoke
- School of Kinesiology and Health Science, and Muscle Health Research Centre, York University, 4700 Keele Street, Toronto, Ontario, M3J 1P3 Canada.
| | - Brendan E Beatty
- School of Kinesiology and Health Science, and Muscle Health Research Centre, York University, 4700 Keele Street, Toronto, Ontario, M3J 1P3 Canada
| | - Scot R Kimball
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Simon S Wing
- Department of Medicine, McGill University and the Research Institute of the McGill University Health Centre, the Montreal Diabetes Research Centre, Montréal, Quebec, H4A 3J1. Canada
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194
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Akpinar HA, Kahraman H, Yaman I. Ochratoxin A Sequentially Activates Autophagy and the Ubiquitin-Proteasome System. Toxins (Basel) 2019; 11:E615. [PMID: 31653047 PMCID: PMC6891609 DOI: 10.3390/toxins11110615] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/12/2019] [Accepted: 10/23/2019] [Indexed: 12/21/2022] Open
Abstract
Ochratoxin A (OTA) is a carcinogenic mycotoxin, which is produced by Aspergillus and Penicillium genera of fungi and commonly contaminates food and feed. We and others have previously shown that OTA causes sustained activation of PI3K/AKT and MAPK/ERK1-2 signaling pathways in different cell types and animal models. Given the close relationship between cellular signaling activity and protein stability, we were curious whether increased PI3K/AKT and MAPK/ERK1-2 signaling may be the result of OTA-stimulated alterations in proteolytic activity. We show that both of the major proteolytic systems, autophagy, and the ubiquitin-proteasome system (UPS), are activated upon OTA exposure in human kidney proximal tubule HK-2 and mouse embryonic fibroblast (MEF) cells. OTA stimulates transient autophagic activity at early time points of treatment but autophagic activity subsides after 6 h even in the sustained presence of OTA. Interestingly, OTA exposure also results in increased cell death in wild-type MEF cells but not in autophagy-halted Atg5-deficient cells, suggesting that autophagy exerts a pro-death effect on OTA-induced cytotoxicity. In addition, prolonged OTA exposure decreased ubiquitinated protein levels by increasing proteasomal activity. Using purified and cellular proteasomes, we observed enhanced chymotrypsin-, caspase-, and trypsin-like activities of the 26S but not the 20S proteasome in the presence of OTA. However, in the cellular context, increased proteasomal activity depended on prior induction of autophagy. Our results suggest that autophagy and subsequent UPS activation are responsible for sustained activation of PI3K/AKT and MAPK/ERK1-2 pathways through regulating the levels of critical phosphatases VHR/DUSP3, DUSP4, and PHLPP, which are known to be involved in OTA toxicity and carcinogenicity.
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Affiliation(s)
- Hafize Aysin Akpinar
- Molecular Toxicology and Cancer Research Laboratory, Department of Molecular Biology and Genetics, Bogazici University, Bebek-Istanbul 34342, Turkey.
| | - Hilal Kahraman
- Molecular Toxicology and Cancer Research Laboratory, Department of Molecular Biology and Genetics, Bogazici University, Bebek-Istanbul 34342, Turkey.
| | - Ibrahim Yaman
- Molecular Toxicology and Cancer Research Laboratory, Department of Molecular Biology and Genetics, Bogazici University, Bebek-Istanbul 34342, Turkey.
- Center for Life Sciences and Technologies, Bogazici University, Bebek-Istanbul 34342, Turkey.
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195
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Ryskalin L, Busceti CL, Biagioni F, Limanaqi F, Familiari P, Frati A, Fornai F. Prion Protein in Glioblastoma Multiforme. Int J Mol Sci 2019; 20:ijms20205107. [PMID: 31618844 PMCID: PMC6834196 DOI: 10.3390/ijms20205107] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/07/2019] [Accepted: 10/14/2019] [Indexed: 12/13/2022] Open
Abstract
The cellular prion protein (PrPc) is an evolutionarily conserved cell surface protein encoded by the PRNP gene. PrPc is ubiquitously expressed within nearly all mammalian cells, though most abundantly within the CNS. Besides being implicated in the pathogenesis and transmission of prion diseases, recent studies have demonstrated that PrPc contributes to tumorigenesis by regulating tumor growth, differentiation, and resistance to conventional therapies. In particular, PrPc over-expression has been related to the acquisition of a malignant phenotype of cancer stem cells (CSCs) in a variety of solid tumors, encompassing pancreatic ductal adenocarcinoma (PDAC), osteosarcoma, breast cancer, gastric cancer, and primary brain tumors, mostly glioblastoma multiforme (GBM). Thus, PrPc is emerging as a key in maintaining glioblastoma cancer stem cells’ (GSCs) phenotype, thereby strongly affecting GBM infiltration and relapse. In fact, PrPc contributes to GSCs niche’s maintenance by modulating GSCs’ stem cell-like properties while restraining them from differentiation. This is the first review that discusses the role of PrPc in GBM. The manuscript focuses on how PrPc may act on GSCs to modify their expression and translational profile while making the micro-environment surrounding the GSCs niche more favorable to GBM growth and infiltration.
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Affiliation(s)
- Larisa Ryskalin
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, via Roma 55, 56126 Pisa, Italy.
| | - Carla L Busceti
- I.R.C.C.S. Neuromed, via Atinense 18, 86077 Pozzilli, Italy.
| | | | - Fiona Limanaqi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, via Roma 55, 56126 Pisa, Italy.
| | - Pietro Familiari
- Department of Neuroscience, Mental Health and Sense Organs NESMOS, Sapienza University of Rome, 00185 Rome, Italy.
| | | | - Francesco Fornai
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, via Roma 55, 56126 Pisa, Italy.
- I.R.C.C.S. Neuromed, via Atinense 18, 86077 Pozzilli, Italy.
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196
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Abstract
Traditional animal models have been used to make seminal discoveries in biomedical research including a better understanding of the biology of the aging process. However, translation of these findings from laboratory to clinical populations has likely been hindered due to fundamental biological and physiological differences between common laboratory animals and humans. Non-human primates (NHP) may serve as an effective bridge towards translation, and short-lived NHP like the common marmoset offer many advantages as models for aging research. Here, we address these advantages and discuss what is currently understood about the changes in physiology and pathology that occur with age in the marmoset. In addition, we discuss how aging research might best utilize this model resource, and outline an ongoing study to address whether pharmaceutical intervention can slow aging in the marmoset. With this manuscript, we clarify how common marmosets might assist researchers in geroscience as a potential model for pre-clinical translation.
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Affiliation(s)
- Corinna N Ross
- Department of Science and Mathematics, Texas A&M University San Antonio, San Antonio, TX, USA.,The Sam and Ann Barshop Institute for Longevity and Aging Studies and The University of Texas Health Science Center at San Antonio, San Antonio TX, USA
| | - Adam B Salmon
- The Sam and Ann Barshop Institute for Longevity and Aging Studies and The University of Texas Health Science Center at San Antonio, San Antonio TX, USA.,Department of Molecular Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.,Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, TX, USA
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197
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Ramalingam M, Huh YJ, Lee YI. The Impairments of α-Synuclein and Mechanistic Target of Rapamycin in Rotenone-Induced SH-SY5Y Cells and Mice Model of Parkinson's Disease. Front Neurosci 2019; 13:1028. [PMID: 31611767 PMCID: PMC6769080 DOI: 10.3389/fnins.2019.01028] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 09/10/2019] [Indexed: 12/11/2022] Open
Abstract
Parkinson's disease (PD) is characterized by selective degeneration of dopaminergic (DAergic) neurons in the substantia nigra pars compacta (SNpc). α-synuclein (α-syn) is known to regulate mitochondrial function and both PINK1 and Parkin have been shown to eliminate damaged mitochondria in PD. Mechanistic target of rapamycin (mTOR) is expressed in several distinct subcellular compartments and mediates the effects of nutrients, growth factors, and stress on cell growth. However, the contributions of these various regulators to DAergic cell death have been demonstrated mainly in culture with serum, which is known to dramatically influence endogenous growth rate and toxin susceptibility through nutrient and growth factor signaling. Therefore, we compared neurotoxicity induced by the mitochondrial inhibitor rotenone (ROT, 5 or 10 μM for 24 h) in SH-SY5Y cells cultured with 10% fetal bovine serum (FBS), 1% FBS, or 1% bovine serum albumin (BSA, serum-free). In addition, C57BL/6J mice were injected with 12 μg ROT into the right striatum, and brains examined by histology and Western blotting 2 weeks later for evidence of DAergic cell death and the underlying signaling mechanisms. ROT dose-dependently reduced SH-SY5Y cell viability in all serum groups without a significant effect of serum concentration. ROT injection also significantly reduced immunoreactivity for the DAergic cell marker tyrosine hydroxylase (TH) in both the mouse striatum and SNpc. Western blotting revealed that ROT inhibited TH and Parkin expression while increasing α-syn and PINK1 expression in both SH-SY5Y cells and injected mice, consistent with disruption of mitochondrial function. Moreover, expression levels of the mTOR signaling pathway components mTORC, AMP-activated protein kinase (AMPK), ULK1, and ATG13 were altered in ROT-induced PD. Further, serum level influenced mTOR signaling in the absence of ROT and the changes in response to ROT. Signs of endoplasmic reticulum (ER) stress and altered expression of tethering proteins mediating mitochondria-associated ER contacts (MAMs) were also altered concomitant with ROT-induced neurodegeneration. Taken together, this study demonstrates that complex mechanism involving mitochondrial dysfunction, altered mTOR nutrient-sensing pathways, ER stress, and disrupted MAM protein dynamics are involved in DAergic neurodegeneration in response to ROT.
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Affiliation(s)
| | | | - Yun-Il Lee
- Well Aging Research Center, DGIST, Daegu, South Korea
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198
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Njomen E, Tepe JJ. Regulation of Autophagic Flux by the 20S Proteasome. Cell Chem Biol 2019; 26:1283-1294.e5. [PMID: 31327703 PMCID: PMC6754308 DOI: 10.1016/j.chembiol.2019.07.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 04/24/2019] [Accepted: 06/28/2019] [Indexed: 12/13/2022]
Abstract
The proteolytic arm of the protein homeostasis network is maintained by both the ubiquitin-proteasome system (UPS) and autophagy. A well-balanced crosstalk between the two catabolic pathways ensures energy-efficient maintenance of cellular function. Our current understanding of the crosstalk between the UPS and autophagy is centered around substrate ubiquitination. Herein we report an additional method of crosstalk involving ubiquitin-independent 20S proteasome regulation of autophagosome-lysosome fusion. We found that enhancement of 20S proteasome activity increased the degradation of the disordered soluble N-ethylmaleimide-sensitive factor activating protein receptor proteins, synaptosomal-associated protein 29 (SNAP29), and syntaxin 17 (STX17), but not vesicle-associated membrane protein 8. This resulted in a reduction of autophagosome-lysosome fusion, which was ameliorated upon overexpression of both SNAP29 and STX17. In all, we herein present a mechanism of crosstalk between the proteasome and autophagy pathway that is regulated by ubiquitin-independent 20S proteasome-mediated degradation of SNAP29 and STX17.
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Affiliation(s)
- Evert Njomen
- Department of Chemistry and Pharmacology & Toxicology, Michigan State University, East Lansing, MI 48824, USA
| | - Jetze J Tepe
- Department of Chemistry and Pharmacology & Toxicology, Michigan State University, East Lansing, MI 48824, USA.
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199
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Abstract
The proteasome degrades most cellular proteins in a controlled and tightly regulated manner and thereby controls many processes, including cell cycle, transcription, signalling, trafficking and protein quality control. Proteasomal degradation is vital in all cells and organisms, and dysfunction or failure of proteasomal degradation is associated with diverse human diseases, including cancer and neurodegeneration. Target selection is an important and well-established way to control protein degradation. In addition, mounting evidence indicates that cells adjust proteasome-mediated degradation to their needs by regulating proteasome abundance through the coordinated expression of proteasome subunits and assembly chaperones. Central to the regulation of proteasome assembly is TOR complex 1 (TORC1), which is the master regulator of cell growth and stress. This Review discusses how proteasome assembly and the regulation of proteasomal degradation are integrated with cellular physiology, including the interplay between the proteasome and autophagy pathways. Understanding these mechanisms has potential implications for disease therapy, as the misregulation of proteasome function contributes to human diseases such as cancer and neurodegeneration.
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200
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Kors S, Geijtenbeek K, Reits E, Schipper-Krom S. Regulation of Proteasome Activity by (Post-)transcriptional Mechanisms. Front Mol Biosci 2019; 6:48. [PMID: 31380390 PMCID: PMC6646590 DOI: 10.3389/fmolb.2019.00048] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 06/11/2019] [Indexed: 12/23/2022] Open
Abstract
Intracellular protein synthesis, folding, and degradation are tightly controlled processes to ensure proper protein homeostasis. The proteasome is responsible for the degradation of the majority of intracellular proteins, which are often targeted for degradation via polyubiquitination. However, the degradation rate of proteins is also affected by the capacity of proteasomes to recognize and degrade these substrate proteins. This capacity is regulated by a variety of proteasome modulations including (1) changes in complex composition, (2) post-translational modifications, and (3) altered transcription of proteasomal subunits and activators. Various diseases are linked to proteasome modulation and altered proteasome function. A better understanding of these modulations may offer new perspectives for therapeutic intervention. Here we present an overview of these three proteasome modulating mechanisms to give better insight into the diversity of proteasomes.
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Affiliation(s)
- Suzan Kors
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Karlijne Geijtenbeek
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Eric Reits
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Sabine Schipper-Krom
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
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