1
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Kamińska D, Skrzycki M. Lipid droplets, autophagy, and ER stress as key (survival) pathways during ischemia-reperfusion of transplanted grafts. Cell Biol Int 2024; 48:253-279. [PMID: 38178581 DOI: 10.1002/cbin.12114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 11/30/2023] [Accepted: 12/14/2023] [Indexed: 01/06/2024]
Abstract
Ischemia-reperfusion injury is an event concerning any organ under a procedure of transplantation. The early result of ischemia is hypoxia, which causes malfunction of mitochondria and decrease in cellular ATP. This leads to disruption of cellular metabolism. Reperfusion also results in cell damage due to reoxygenation and increased production of reactive oxygen species, and later by induced inflammation. In damaged and hypoxic cells, the endoplasmic reticulum (ER) stress pathway is activated by increased amount of damaged or misfolded proteins, accumulation of free fatty acids and other lipids due to inability of their oxidation (lipotoxicity). ER stress is an adaptive response and a survival pathway, however, its prolonged activity eventually lead to induction of apoptosis. Sustaining cell functionality in stress conditions is a great challenge for transplant surgeons as it is crucial for maintaining a desired level of graft vitality. Pathways counteracting negative consequences of ischemia-reperfusion are autophagy and lipid droplets (LD) metabolism. Autophagy remove damaged organelles and molecules driving them to lysosomes, digested simpler compounds are energy source for the cell. Mitophagy and ER-phagy results in improvement of cell energetic balance and alleviation of ER stress. This is important in sustaining metabolic homeostasis and thus cell survival. LD metabolism is connected with autophagy as LD are degraded by lipophagy, a source of free fatty acids and glycerol-thus autophagy and LD can readily remove lipotoxic compounds in the cell. In conclusion, monitoring and pharmaceutic regulation of those pathways during transplantation procedure might result in increased/improved vitality of transplanted organ.
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Affiliation(s)
- Daria Kamińska
- Department of Radiotherapy, Maria Sklodowska-Curie National Research Institute of Oncology, Warszawa, Poland
| | - Michał Skrzycki
- Chair and Department of Biochemistry, Medical University of Warsaw, Warszawa, Poland
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2
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Kern J, Schilling D, Schneeweis C, Schmid RM, Schneider G, Combs SE, Dobiasch S. Identification of the unfolded protein response pathway as target for radiosensitization in pancreatic cancer. Radiother Oncol 2024; 191:110059. [PMID: 38135186 DOI: 10.1016/j.radonc.2023.110059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 12/12/2023] [Accepted: 12/15/2023] [Indexed: 12/24/2023]
Abstract
BACKGROUND AND PURPOSE Due to the high intrinsic radioresistance of pancreatic ductal adenocarcinoma (PDAC), radiotherapy (RT) is only beneficial in 30% of patients. Therefore, this study aimed to identify targets to improve the efficacy of RT in PDAC. MATERIALS AND METHODS Alamar Blue proliferation and colony formation assay (CFA) were used to determine the radioresponse of a cohort of 38 murine PDAC cell lines. A gene set enrichment analysis was performed to reveal differentially expressed pathways. CFA, cell cycle distribution, γH2AX FACS analysis, and Caspase 3/7 SYTOX assay were used to examine the effect of a combination treatment using KIRA8 as an IRE1α-inhibitor and Ceapin-A7 as an inhibitor against ATF6. RESULTS The unfolded protein response (UPR) was identified as a pathway highly expressed in radioresistant cell lines. Using the IRE1α-inhibitor KIRA8 or the ATF6-inhibitor Ceapin-A7 in combination with radiation, a radiosensitizing effect was observed in radioresistant cell lines, but no substantial alteration of the radioresponse in radiosensitive cell lines. Mechanistically, increased apoptosis by KIRA8 in combination with radiation and a cell cycle arrest in the G1 phase after ATF6 inhibition and radiation have been observed in radioresistant cell lines. CONCLUSION So, our data show evidence that the UPR is involved in radioresistance of PDAC. Increased apoptosis and a G1 cell cycle arrest seem to be responsible for the radiosensitizing effect of UPR inhibition. These findings are supportive for developing novel combination treatment concepts in PDAC to overcome radioresistance.
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Affiliation(s)
- Jana Kern
- Department of Radiation Oncology, School of Medicine, Klinikum rechts der Isar, Technical University Munich (TUM), Munich, Germany
| | - Daniela Schilling
- Department of Radiation Oncology, School of Medicine, Klinikum rechts der Isar, Technical University Munich (TUM), Munich, Germany; Institute of Radiation Medicine (IRM), Department of Radiation Sciences, Helmholtz Zentrum Munich, Neuherberg, Germany
| | - Christian Schneeweis
- Department of Medicine II, School of Medicine, Klinikum rechts der Isar, Technical University Munich (TUM), Munich, Germany
| | - Roland M Schmid
- Department of Medicine II, School of Medicine, Klinikum rechts der Isar, Technical University Munich (TUM), Munich, Germany
| | - Günter Schneider
- Department of Medicine II, School of Medicine, Klinikum rechts der Isar, Technical University Munich (TUM), Munich, Germany; Department of General Visceral and Pediatric Surgery, University Medical Center Göttingen, Germany
| | - Stephanie E Combs
- Department of Radiation Oncology, School of Medicine, Klinikum rechts der Isar, Technical University Munich (TUM), Munich, Germany; Institute of Radiation Medicine (IRM), Department of Radiation Sciences, Helmholtz Zentrum Munich, Neuherberg, Germany; German Cancer Consortium (DKTK), Partner Site Munich, Munich, Germany
| | - Sophie Dobiasch
- Department of Radiation Oncology, School of Medicine, Klinikum rechts der Isar, Technical University Munich (TUM), Munich, Germany; Institute of Radiation Medicine (IRM), Department of Radiation Sciences, Helmholtz Zentrum Munich, Neuherberg, Germany; German Cancer Consortium (DKTK), Partner Site Munich, Munich, Germany.
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3
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He J, Zhou Y, Sun L. Emerging mechanisms of the unfolded protein response in therapeutic resistance: from chemotherapy to Immunotherapy. Cell Commun Signal 2024; 22:89. [PMID: 38297380 PMCID: PMC10832166 DOI: 10.1186/s12964-023-01438-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 12/12/2023] [Indexed: 02/02/2024] Open
Abstract
The accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) causes ER stress and activates the unfolded protein response (UPR). As an adaptive cellular response to hostile microenvironments, such as hypoxia, nutrient deprivation, oxidative stress, and chemotherapeutic drugs, the UPR is activated in diverse cancer types and functions as a dynamic tumour promoter in cancer development; this role of the UPR indicates that regulation of the UPR can be utilized as a target for tumour treatment. T-cell exhaustion mainly refers to effector T cells losing their effector functions and expressing inhibitory receptors, leading to tumour immune evasion and the loss of tumour control. Emerging evidence suggests that the UPR plays a crucial role in T-cell exhaustion, immune evasion, and resistance to immunotherapy. In this review, we summarize the molecular basis of UPR activation, the effect of the UPR on immune evasion, the emerging mechanisms of the UPR in chemotherapy and immunotherapy resistance, and agents that target the UPR for tumour therapeutics. An understanding of the role of the UPR in immune evasion and therapeutic resistance will be helpful to identify new therapeutic modalities for cancer treatment. Video Abstract.
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Affiliation(s)
- Jiang He
- Xiangya Cancer Center, Xiangya Hospital, Central South University, Changsha, 410008, China.
- Key Laboratory of Molecular Radiation Oncology Hunan Province, Changsha, 410008, China.
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, 410008, Huan, China.
- Hunan International Science and Technology Collaboration Base of Precision Medicine for Cancer, Changsha, 410008, China.
- Center for Molecular Imaging of Central, South University, Xiangya Hospital, Changsha, 410008, China.
| | - You Zhou
- Department of Pathology, Tongji Medical College Union Hospital, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Lunquan Sun
- Xiangya Cancer Center, Xiangya Hospital, Central South University, Changsha, 410008, China.
- Key Laboratory of Molecular Radiation Oncology Hunan Province, Changsha, 410008, China.
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, 410008, Huan, China.
- Hunan International Science and Technology Collaboration Base of Precision Medicine for Cancer, Changsha, 410008, China.
- Center for Molecular Imaging of Central, South University, Xiangya Hospital, Changsha, 410008, China.
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4
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Zhang SX, Wang JJ, Starr CR, Lee EJ, Park KS, Zhylkibayev A, Medina A, Lin JH, Gorbatyuk M. The endoplasmic reticulum: Homeostasis and crosstalk in retinal health and disease. Prog Retin Eye Res 2024; 98:101231. [PMID: 38092262 PMCID: PMC11056313 DOI: 10.1016/j.preteyeres.2023.101231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 12/05/2023] [Accepted: 12/06/2023] [Indexed: 12/19/2023]
Abstract
The endoplasmic reticulum (ER) is the largest intracellular organelle carrying out a broad range of important cellular functions including protein biosynthesis, folding, and trafficking, lipid and sterol biosynthesis, carbohydrate metabolism, and calcium storage and gated release. In addition, the ER makes close contact with multiple intracellular organelles such as mitochondria and the plasma membrane to actively regulate the biogenesis, remodeling, and function of these organelles. Therefore, maintaining a homeostatic and functional ER is critical for the survival and function of cells. This vital process is implemented through well-orchestrated signaling pathways of the unfolded protein response (UPR). The UPR is activated when misfolded or unfolded proteins accumulate in the ER, a condition known as ER stress, and functions to restore ER homeostasis thus promoting cell survival. However, prolonged activation or dysregulation of the UPR can lead to cell death and other detrimental events such as inflammation and oxidative stress; these processes are implicated in the pathogenesis of many human diseases including retinal disorders. In this review manuscript, we discuss the unique features of the ER and ER stress signaling in the retina and retinal neurons and describe recent advances in the research to uncover the role of ER stress signaling in neurodegenerative retinal diseases including age-related macular degeneration, inherited retinal degeneration, achromatopsia and cone diseases, and diabetic retinopathy. In some chapters, we highlight the complex interactions between the ER and other intracellular organelles focusing on mitochondria and illustrate how ER stress signaling regulates common cellular stress pathways such as autophagy. We also touch upon the integrated stress response in retinal degeneration and diabetic retinopathy. Finally, we provide an update on the current development of pharmacological agents targeting the UPR response and discuss some unresolved questions and knowledge gaps to be addressed by future research.
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Affiliation(s)
- Sarah X Zhang
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States; Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States.
| | - Josh J Wang
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Christopher R Starr
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Eun-Jin Lee
- Department of Ophthalmology and Byers Eye Institute, Stanford University, Stanford, CA, United States; VA Palo Alto Healthcare System, Palo Alto, CA, United States; Department of Pathology, Stanford University, Stanford, CA, United States
| | - Karen Sophia Park
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Assylbek Zhylkibayev
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Andy Medina
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Jonathan H Lin
- Department of Ophthalmology and Byers Eye Institute, Stanford University, Stanford, CA, United States; VA Palo Alto Healthcare System, Palo Alto, CA, United States; Department of Pathology, Stanford University, Stanford, CA, United States
| | - Marina Gorbatyuk
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
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5
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Kubra KT, Barabutis N. Ceapin-A7 potentiates lipopolysaccharide-induced endothelial injury. J Biochem Mol Toxicol 2023; 37:e23460. [PMID: 37431958 PMCID: PMC10782819 DOI: 10.1002/jbt.23460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 06/14/2023] [Accepted: 07/04/2023] [Indexed: 07/12/2023]
Abstract
Barrier dysfunction is the hallmark of severe lung injury, including acute respiratory distress syndrome. Efficient medical countermeasures to counteract endothelial hyperpermeability do not exist, hence the mortality rates of disorders related to barrier abnormalities are unacceptable high. The unfolded protein response is a highly conserved mechanism, which aims to support the cells against endoplasmic reticulum stress, and ATF6 is a protein sensor that triggers its activation. In the current study, we investigate the effects of ATF6 suppression in LPS-induced endothelial inflammation. Our observations suggest that Ceapin-A7, which is an ATF6 suppressor, potentiates LPS-induced STAT3 and JAK2 activation. Hence ATF6 activation may serve as a new therapeutic possibility toward diseases related to barrier dysfunction.
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Affiliation(s)
- Khadeja-Tul Kubra
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, Louisiana 71201, USA
| | - Nektarios Barabutis
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, Louisiana 71201, USA
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6
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Pu S, Pan Y, Zhang Q, You T, Yue T, Zhang Y, Wang M. Endoplasmic Reticulum Stress and Mitochondrial Stress in Drug-Induced Liver Injury. Molecules 2023; 28:molecules28073160. [PMID: 37049925 PMCID: PMC10095764 DOI: 10.3390/molecules28073160] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 03/26/2023] [Accepted: 03/29/2023] [Indexed: 04/05/2023] Open
Abstract
Drug-induced liver injury (DILI) is a widespread and harmful disease closely linked to mitochondrial and endoplasmic reticulum stress (ERS). Globally, severe drug-induced hepatitis, cirrhosis, and liver cancer are the primary causes of liver-related morbidity and mortality. A hallmark of DILI is ERS and changes in mitochondrial morphology and function, which increase the production of reactive oxygen species (ROS) in a vicious cycle of mutually reinforcing stress responses. Several pathways are maladapted to maintain homeostasis during DILI. Here, we discuss the processes of liver injury caused by several types of drugs that induce hepatocyte stress, focusing primarily on DILI by ERS and mitochondrial stress. Importantly, both ERS and mitochondrial stress are mediated by the overproduction of ROS, destruction of Ca2+ homeostasis, and unfolded protein response (UPR). Additionally, we review new pathways and potential pharmacological targets for DILI to highlight new possibilities for DILI treatment and mitigation.
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Affiliation(s)
- Sisi Pu
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China
| | - Yangyang Pan
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China
| | - Qian Zhang
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China
| | - Ting You
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China
| | - Tao Yue
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China
| | - Yuxing Zhang
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China
| | - Meng Wang
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China
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7
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Zhou H, Zhang T, Chen L, Cui F, Xu C, Peng J, Ma W, Huang J, Sheng X, Liu M, Zhao F. The functional implication of ATF6α in castration-resistant prostate cancer cells. FASEB J 2023; 37:e22758. [PMID: 36607288 DOI: 10.1096/fj.202201347r] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/30/2022] [Accepted: 12/22/2022] [Indexed: 01/07/2023]
Abstract
Stress in the endoplasmic reticulum (ER) may perturb proteostasis and activates the unfolded protein response (UPR). UPR activation is frequently observed in cancer cells and is believed to fuel cancer progression. Here, we report that one of the three UPR sensors, ATF6α, was associated with prostate cancer (PCa) development, while both genetic and pharmacological inhibition of ATF6α impaired the survival of castration-resistance PCa (CRPC) cells. Transcriptomic analyses identified the molecular pathways deregulated upon ATF6α depletion, and also discovered considerable disparity in global gene expression between ATF6α knockdown and Ceapin-A7 treatment. In addition, combined analyses of human CRPC bulk RNA-seq and single-cell RNA-seq (scRNA-seq) public datasets confirmed that CRPC tumors with higher ATF6α activity displayed higher androgen receptor (AR) activity, proliferative and neuroendocrine (NE) like phenotypes, as well as immunosuppressive features. Lastly, we identified a 14-gene set as ATF6α NE gene signature with encouraging prognostic power. In conclusion, our results indicate that ATF6α is correlated with PCa progression and is functionally relevant to CRPC cell survival. Both specificity and efficacy of ATF6α inhibitors require further refinement and evaluation.
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Affiliation(s)
- Hongqing Zhou
- The Second Ward of Urology, Qujing Affiliated Hospital of Kunming Medical University, Qujing, China
| | - Tingting Zhang
- Key Laboratory of Environmental Health, Ministry of Education & Ministry of Environmental Protection, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Liang Chen
- Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Fengzhen Cui
- Key Laboratory of Environmental Health, Ministry of Education & Ministry of Environmental Protection, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chenxiang Xu
- The Second Ward of Urology, Qujing Affiliated Hospital of Kunming Medical University, Qujing, China
| | - Jiaxi Peng
- The Second Ward of Urology, Qujing Affiliated Hospital of Kunming Medical University, Qujing, China
| | - Weixiang Ma
- Department of Pharmacology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Jirong Huang
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xia Sheng
- Key Laboratory of Environmental Health, Ministry of Education & Ministry of Environmental Protection, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Mingsheng Liu
- The Second Ward of Urology, Qujing Affiliated Hospital of Kunming Medical University, Qujing, China
| | - Faming Zhao
- Key Laboratory of Environmental Health, Ministry of Education & Ministry of Environmental Protection, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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8
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Di Cara F, Savary S, Kovacs WJ, Kim P, Rachubinski RA. The peroxisome: an up-and-coming organelle in immunometabolism. Trends Cell Biol 2023; 33:70-86. [PMID: 35788297 DOI: 10.1016/j.tcb.2022.06.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/31/2022] [Accepted: 06/03/2022] [Indexed: 12/27/2022]
Abstract
Peroxisomes are essential metabolic organelles, well known for their roles in the metabolism of complex lipids and reactive ionic species. In the past 10 years, peroxisomes have also been cast as central regulators of immunity. Lipid metabolites of peroxisomes, such as polyunsaturated fatty acids (PUFAs), are precursors for important immune mediators, including leukotrienes (LTs) and resolvins. Peroxisomal redox metabolism modulates cellular immune signaling such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation. Additionally, peroxisomal β-oxidation and ether lipid synthesis control the development and aspects of the activation of both innate and adaptive immune cells. Finally, peroxisome number and metabolic activity have been linked to inflammatory diseases. These discoveries have opened avenues of investigation aimed at targeting peroxisomes for therapeutic intervention in immune disorders, inflammation, and cancer.
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Affiliation(s)
- Francesca Di Cara
- Dalhousie University, Department of Microbiology and Immunology, Halifax, NS B3K 6R8, Canada.
| | - Stéphane Savary
- Lab. Bio-PeroxIL EA7270, University of Bourgogne Franche-Comté, 6 Bd Gabriel, 21000 Dijon, France
| | - Werner J Kovacs
- Institute of Molecular Health Sciences, Swiss Federal Institute of Technology in Zurich (ETH Zürich), Zurich, Switzerland
| | - Peter Kim
- Cell Biology Program, Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, Canada; Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, South Korea
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9
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Kubra KT, Akhter MS, Saini Y, Kousoulas KG, Barabutis N. Activating transcription factor 6 protects against endothelial barrier dysfunction. Cell Signal 2022; 99:110432. [PMID: 35933031 PMCID: PMC10413362 DOI: 10.1016/j.cellsig.2022.110432] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 07/30/2022] [Accepted: 08/01/2022] [Indexed: 12/17/2022]
Abstract
BACKGROUND Endothelial hyperpermeability is associated with sepsis and acute respiratory distress syndrome (ARDS). The identification of molecular pathways involved in barrier dysfunction; may reveal promising therapeutic targets to combat ARDS. Unfolded protein response (UPR) is a highly conserved molecular pathway, which ameliorates endoplasmic reticulum stress. The present work focuses on the effects of ATF6, which is a UPR sensor, in lipopolysaccharides (LPS)-induced endothelial hyperpermeability. METHODS The in vitro effects of AA147 and Ceapin-A7 in LPS-induced endothelial barrier dysfunction were investigated in bovine pulmonary artery endothelial cells (BPAEC). Small interfering (si) RNA was utilized to "silence" ATF6, and electric cell-substrate impedance sensing (ECIS) measured transendothelial resistance. Fluorescein isothiocyanate (FITC)-dextran assay was utilized to assess paracellular permeability. Protein expression levels were evaluated with Western blotting, and cell viability with MTT assay. RESULTS We demonstrated that AA147 prevents LPS-induced barrier disruption by counteracting Cofilin and myosin light chain 2 (MLC2) activation, as well as VE-Cadherin phosphorylation. Moreover, this ATF6 inducer opposed LPS-triggered decrease in transendothelial resistance (TEER), as well as LPS-induced paracellular hyperpermeability. On the other hand, ATF6 suppression due to Ceapin-A7 or small interfering RNA exerted the opposite effects, and potentiated LPS-induced endothelial barrier disruption. Moderate concentrations of both ATF6 modulators did not affect cell viability. CONCLUSIONS ATF6 activation protects against endothelial barrier function, suggesting that this UPR sensor may serve as a therapeutic target for sepsis and ARDS.
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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
| | - Yogesh Saini
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Konstantin G Kousoulas
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, 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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10
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Jin X, Liu J, Wang W, Li J, Liu G, Qiu R, Yang M, Liu M, Yang L, Du X, Lei B. Identification of Age-associated Proteins and Functional Alterations in Human Retinal Pigment Epithelium. GENOMICS, PROTEOMICS & BIOINFORMATICS 2022; 20:633-647. [PMID: 35752290 PMCID: PMC9880895 DOI: 10.1016/j.gpb.2022.06.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 05/15/2022] [Accepted: 06/13/2022] [Indexed: 01/31/2023]
Abstract
Retinal pigment epithelium (RPE) has essential functions, such as nourishing and supporting the neural retina, and is of vital importance in the pathogenesis of age-related retinal degeneration. However, the exact molecular changes of RPE during aging remain poorly understood. Here, we isolated human primary RPE (hRPE) cells from 18 eye donors distributed over a wide age range (10-67 years old). A quantitative proteomic analysis was performed to analyze changes in their intracellular and secreted proteins. Age-group related subtypes and age-associated proteins were revealed and potential age-associated mechanisms were validated in ARPE-19 and hRPE cells. The results of proteomic data analysis and verifications suggest that RNF123- and RNF149-related protein ubiquitination plays an important role in protecting hRPE cells from oxidative damage during aging. In older hRPE cells, apoptotic signaling-related pathways were up-regulated, and endoplasmic reticulum organization was down-regulated both in the intracellular and secreted proteomes. Our work paints a detailed molecular picture of hRPE cells during the aging process and provides new insights into the molecular characteristics of RPE during aging and under other related clinical retinal conditions.
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Affiliation(s)
- Xiuxiu Jin
- Henan Eye Institute, Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou 450003, China,Branch of National Clinical Research Center for Ocular Disease, Henan Provincial People’s Hospital, Zhengzhou 450003, China,School of Medicine, Henan Provincial People’s Hospital, Henan University, Zhengzhou 450003, China
| | - Jingyang Liu
- Henan Eye Institute, Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou 450003, China,Branch of National Clinical Research Center for Ocular Disease, Henan Provincial People’s Hospital, Zhengzhou 450003, China
| | - Weiping Wang
- Henan Eye Institute, Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou 450003, China,Branch of National Clinical Research Center for Ocular Disease, Henan Provincial People’s Hospital, Zhengzhou 450003, China
| | - Jiangfeng Li
- School of Basic Medical Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Guangming Liu
- Henan Eye Institute, Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou 450003, China,Branch of National Clinical Research Center for Ocular Disease, Henan Provincial People’s Hospital, Zhengzhou 450003, China
| | - Ruiqi Qiu
- Henan Eye Institute, Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou 450003, China,Branch of National Clinical Research Center for Ocular Disease, Henan Provincial People’s Hospital, Zhengzhou 450003, China
| | - Mingzhu Yang
- Henan Eye Institute, Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou 450003, China,Branch of National Clinical Research Center for Ocular Disease, Henan Provincial People’s Hospital, Zhengzhou 450003, China
| | - Meng Liu
- Henan Eye Institute, Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou 450003, China,Academy of Medical Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Lin Yang
- Henan Eye Institute, Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou 450003, China,Academy of Medical Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Xiaofeng Du
- Henan Eye Institute, Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou 450003, China,Branch of National Clinical Research Center for Ocular Disease, Henan Provincial People’s Hospital, Zhengzhou 450003, China
| | - Bo Lei
- Henan Eye Institute, Henan Eye Hospital, People’s Hospital of Zhengzhou University, Henan Provincial People’s Hospital, Zhengzhou 450003, China,Branch of National Clinical Research Center for Ocular Disease, Henan Provincial People’s Hospital, Zhengzhou 450003, China,Academy of Medical Sciences, Zhengzhou University, Zhengzhou 450001, China,Corresponding author.
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11
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Domostegui A, Nieto-Barrado L, Perez-Lopez C, Mayor-Ruiz C. Chasing molecular glue degraders: screening approaches. Chem Soc Rev 2022; 51:5498-5517. [PMID: 35723413 DOI: 10.1039/d2cs00197g] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Protein-protein interactions (PPIs) govern all biological processes. Some small molecules modulate PPIs through induced protein proximity. In particular, molecular glue degraders are monovalent compounds that orchestrate interactions between a target protein and an E3 ubiquitin ligase, prompting the proteasomal degradation of the former. This and other pharmacological strategies of targeted protein degradation (e.g. proteolysis-targeting chimeras - PROTACs) overcome some limitations of traditional occupancy-based therapeutics. Here, we provide an overview of the "molecular glue" concept, with a special focus on natural and synthetic inducers of proximity to E3s. We then briefly highlight the serendipitous discoveries of some clinical and preclinical molecular glue degraders, and discuss the first examples of intentional discoveries. Specifically, we outline the different screening strategies reported in this rapidly evolving arena and our thoughts on future perspectives. By mastering the ability to influence PPIs, molecular glue degraders can induce the degradation of unligandable proteins, thus providing an exciting path forward to broaden the targetable proteome.
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Affiliation(s)
- Ana Domostegui
- IRB Barcelona - Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac, 10, 08028 Barcelona, Spain.
| | - Luis Nieto-Barrado
- IRB Barcelona - Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac, 10, 08028 Barcelona, Spain.
| | - Carles Perez-Lopez
- IRB Barcelona - Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac, 10, 08028 Barcelona, Spain.
| | - Cristina Mayor-Ruiz
- IRB Barcelona - Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac, 10, 08028 Barcelona, Spain.
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12
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Wang M, Cotter E, Wang YJ, Fu X, Whittsette AL, Lynch JW, Wiseman RL, Kelly JW, Keramidas A, Mu TW. Pharmacological activation of ATF6 remodels the proteostasis network to rescue pathogenic GABA A receptors. Cell Biosci 2022; 12:48. [PMID: 35477478 PMCID: PMC9044816 DOI: 10.1186/s13578-022-00783-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 04/05/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genetic variants in the subunits of the gamma-aminobutyric acid type A (GABAA) receptors are implicated in the onset of multiple pathologic conditions including genetic epilepsy. Previous work showed that pathogenic GABAA subunits promote misfolding and inefficient assembly of the GABAA receptors, limiting receptor expression and activity at the plasma membrane. However, GABAA receptors containing variant subunits can retain activity, indicating that enhancing the folding, assembly, and trafficking of these variant receptors offers a potential opportunity to mitigate pathology associated with genetic epilepsy. RESULTS Here, we demonstrate that pharmacologically enhancing endoplasmic reticulum (ER) proteostasis using small molecule activators of the ATF6 (Activating Transcription Factor 6) signaling arm of the unfolded protein response (UPR) increases the assembly, trafficking, and surface expression of variant GABAA receptors. These improvements are attributed to ATF6-dependent remodeling of the ER proteostasis environment, which increases protein levels of pro-folding ER proteostasis factors including the ER chaperone BiP (Immunoglobulin Binding Protein) and trafficking receptors, such as LMAN1 (Lectin Mannose-Binding 1) and enhances their interactions with GABAA receptors. Importantly, we further show that pharmacologic ATF6 activators increase the activity of GABAA receptors at the cell surface, revealing the potential for this strategy to restore receptor activity to levels that could mitigate disease pathogenesis. CONCLUSIONS These results indicate that pharmacologic ATF6 activators offer an opportunity to restore GABAA receptor activity in diseases including genetic epilepsy and point to the potential for similar pharmacologic enhancement of ER proteostasis to improve trafficking of other disease-associated variant ion channels implicated in etiologically-diverse diseases.
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Affiliation(s)
- Meng Wang
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Ave, Cleveland, OH, 44106, USA
| | - Edmund Cotter
- Queensland Brain Institute, the University of Queensland, Brisbane, QLD, 4072, Australia
| | - Ya-Juan Wang
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Ave, Cleveland, OH, 44106, USA
| | - Xu Fu
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Ave, Cleveland, OH, 44106, USA
| | - Angela L Whittsette
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Ave, Cleveland, OH, 44106, USA
| | - Joseph W Lynch
- Queensland Brain Institute, the University of Queensland, Brisbane, QLD, 4072, Australia
| | - R Luke Wiseman
- Department of Molecular Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Jeffery W Kelly
- Department of Molecular Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Angelo Keramidas
- Queensland Brain Institute, the University of Queensland, Brisbane, QLD, 4072, Australia.
| | - Ting-Wei Mu
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Ave, Cleveland, OH, 44106, USA.
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13
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Kim J, Bai H. Peroxisomal Stress Response and Inter-Organelle Communication in Cellular Homeostasis and Aging. Antioxidants (Basel) 2022; 11:192. [PMID: 35204075 PMCID: PMC8868334 DOI: 10.3390/antiox11020192] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/15/2022] [Accepted: 01/16/2022] [Indexed: 12/20/2022] Open
Abstract
Peroxisomes are key regulators of cellular and metabolic homeostasis. These organelles play important roles in redox metabolism, the oxidation of very-long-chain fatty acids (VLCFAs), and the biosynthesis of ether phospholipids. Given the essential role of peroxisomes in cellular homeostasis, peroxisomal dysfunction has been linked to various pathological conditions, tissue functional decline, and aging. In the past few decades, a variety of cellular signaling and metabolic changes have been reported to be associated with defective peroxisomes, suggesting that many cellular processes and functions depend on peroxisomes. Peroxisomes communicate with other subcellular organelles, such as the nucleus, mitochondria, endoplasmic reticulum (ER), and lysosomes. These inter-organelle communications are highly linked to the key mechanisms by which cells surveil defective peroxisomes and mount adaptive responses to protect them from damages. In this review, we highlight the major cellular changes that accompany peroxisomal dysfunction and peroxisomal inter-organelle communication through membrane contact sites, metabolic signaling, and retrograde signaling. We also discuss the age-related decline of peroxisomal protein import and its role in animal aging and age-related diseases. Unlike other organelle stress response pathways, such as the unfolded protein response (UPR) in the ER and mitochondria, the cellular signaling pathways that mediate stress responses to malfunctioning peroxisomes have not been systematically studied and investigated. Here, we coin these signaling pathways as "peroxisomal stress response pathways". Understanding peroxisomal stress response pathways and how peroxisomes communicate with other organelles are important and emerging areas of peroxisome research.
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Affiliation(s)
- Jinoh Kim
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Hua Bai
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
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14
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Replogle JM, Bonnar JL, Pogson AN, Liem CR, Maier NK, Ding Y, Russell BJ, Wang X, Leng K, Guna A, Norman TM, Pak RA, Ramos DM, Ward ME, Gilbert LA, Kampmann M, Weissman JS, Jost M. Maximizing CRISPRi efficacy and accessibility with dual-sgRNA libraries and optimal effectors. eLife 2022; 11:81856. [PMID: 36576240 PMCID: PMC9829409 DOI: 10.7554/elife.81856] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022] Open
Abstract
CRISPR interference (CRISPRi) enables programmable, reversible, and titratable repression of gene expression (knockdown) in mammalian cells. Initial CRISPRi-mediated genetic screens have showcased the potential to address basic questions in cell biology, genetics, and biotechnology, but wider deployment of CRISPRi screening has been constrained by the large size of single guide RNA (sgRNA) libraries and challenges in generating cell models with consistent CRISPRi-mediated knockdown. Here, we present next-generation CRISPRi sgRNA libraries and effector expression constructs that enable strong and consistent knockdown across mammalian cell models. First, we combine empirical sgRNA selection with a dual-sgRNA library design to generate an ultra-compact (1-3 elements per gene), highly active CRISPRi sgRNA library. Next, we compare CRISPRi effectors to show that the recently published Zim3-dCas9 provides an excellent balance between strong on-target knockdown and minimal non-specific effects on cell growth or the transcriptome. Finally, we engineer a suite of cell lines with stable expression of Zim3-dCas9 and robust on-target knockdown. Our results and publicly available reagents establish best practices for CRISPRi genetic screening.
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Affiliation(s)
- Joseph M Replogle
- Medical Scientist Training Program, University of California, San FranciscoSan FranciscoUnited States,Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States,Howard Hughes Medical Institute, Massachusetts Institute of TechnologyCambridgeUnited States,Whitehead Institute for Biomedical ResearchCambridgeUnited States
| | - Jessica L Bonnar
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States,Howard Hughes Medical Institute, Massachusetts Institute of TechnologyCambridgeUnited States,Whitehead Institute for Biomedical ResearchCambridgeUnited States
| | - Angela N Pogson
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States,Howard Hughes Medical Institute, Massachusetts Institute of TechnologyCambridgeUnited States,Whitehead Institute for Biomedical ResearchCambridgeUnited States
| | - Christina R Liem
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Nolan K Maier
- Department of Microbiology, Harvard Medical SchoolBostonUnited States
| | - Yufang Ding
- Department of Microbiology, Harvard Medical SchoolBostonUnited States
| | - Baylee J Russell
- Department of Microbiology, Harvard Medical SchoolBostonUnited States
| | - Xingren Wang
- Department of Microbiology, Harvard Medical SchoolBostonUnited States
| | - Kun Leng
- Medical Scientist Training Program, University of California, San FranciscoSan FranciscoUnited States,Institute for Neurodegenerative Disease, University of California, San FranciscoSan FranciscoUnited States
| | - Alina Guna
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States,Whitehead Institute for Biomedical ResearchCambridgeUnited States
| | - Thomas M Norman
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Ryan A Pak
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Daniel M Ramos
- Center for Alzheimer's Disease and Related Dementias, National Institutes of HealthBethesdaUnited States,National Institute on Aging, National Institutes of HealthBethesdaUnited States
| | - Michael E Ward
- National Institute of Neurological Disorders and Stroke, National Institutes of HealthBethesdaUnited States
| | - Luke A Gilbert
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States,Department of Urology and Helen Diller Family Comprehensive Cancer Center, University of California, San FranciscoSan FranciscoUnited States,Arc InstitutePalo AltoUnited States
| | - Martin Kampmann
- Institute for Neurodegenerative Disease, University of California, San FranciscoSan FranciscoUnited States,Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Jonathan S Weissman
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States,Howard Hughes Medical Institute, Massachusetts Institute of TechnologyCambridgeUnited States,Whitehead Institute for Biomedical ResearchCambridgeUnited States,Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States,David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Marco Jost
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States,Department of Microbiology, Harvard Medical SchoolBostonUnited States
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15
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Ramdas Nair A, Lakhiani P, Zhang C, Macchi F, Sadler KC. A permissive epigenetic landscape facilitates distinct transcriptional signatures of activating transcription factor 6 in the liver. Genomics 2021; 114:107-124. [PMID: 34863900 DOI: 10.1016/j.ygeno.2021.11.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 10/31/2021] [Accepted: 11/26/2021] [Indexed: 12/01/2022]
Abstract
Restoring homeostasis following proteostatic stress hinges on a stress-specific transcriptional signature. How these signatures are regulated is unknown. We use functional genomics to uncover how activating transcription factor 6 (ATF6), a central factor in the unfolded protein response, regulates its target genes in response to toxicant induced and physiological stress in the liver. We identified 652 conserved putative ATF6 targets (CPATs), which functioned in metabolism, development and proteostasis. Strikingly, Atf6 activation in the zebrafish liver by transgenic nAtf6 overexpression, ethanol and arsenic exposure resulted in a distinct CPAT signature for each; with only 34 CPATs differentially expressed in all conditions. In contrast, during liver regeneration in mice resulted in a dynamic differential expression pattern of 53% of CPATs. These CPATs were distinguished by residing in open chromatin, H3K4me3 occupancy and the absence of H3K27me3 on their promoters. This suggests that a permissive epigenetic landscape allows stress-specific Atf6 target gene expression.
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Affiliation(s)
- Anjana Ramdas Nair
- Program in Biology, New York University Abu Dhabi, PO Box. 129188, Abu Dhabi, United Arab Emirates
| | - Priyanka Lakhiani
- Program in Biology, New York University Abu Dhabi, PO Box. 129188, Abu Dhabi, United Arab Emirates
| | - Chi Zhang
- Program in Biology, New York University Abu Dhabi, PO Box. 129188, Abu Dhabi, United Arab Emirates
| | - Filippo Macchi
- Program in Biology, New York University Abu Dhabi, PO Box. 129188, Abu Dhabi, United Arab Emirates
| | - Kirsten C Sadler
- Program in Biology, New York University Abu Dhabi, PO Box. 129188, Abu Dhabi, United Arab Emirates.
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16
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Pharmacological targeting of endoplasmic reticulum stress in disease. Nat Rev Drug Discov 2021; 21:115-140. [PMID: 34702991 DOI: 10.1038/s41573-021-00320-3] [Citation(s) in RCA: 166] [Impact Index Per Article: 55.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/15/2021] [Indexed: 02/08/2023]
Abstract
The accumulation of misfolded proteins in the endoplasmic reticulum (ER) leads to ER stress, resulting in activation of the unfolded protein response (UPR) that aims to restore protein homeostasis. However, the UPR also plays an important pathological role in many diseases, including metabolic disorders, cancer and neurological disorders. Over the last decade, significant effort has been invested in targeting signalling proteins involved in the UPR and an array of drug-like molecules is now available. However, these molecules have limitations, the understanding of which is crucial for their development into therapies. Here, we critically review the existing ER stress and UPR-directed drug-like molecules, highlighting both their value and their limitations.
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17
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Ibe NU, Subramanian A, Mukherjee S. Non-canonical activation of the ER stress sensor ATF6 by Legionella pneumophila effectors. Life Sci Alliance 2021; 4:4/12/e202101247. [PMID: 34635501 PMCID: PMC8507491 DOI: 10.26508/lsa.202101247] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 09/29/2021] [Accepted: 10/01/2021] [Indexed: 12/16/2022] Open
Abstract
Legionella pneumophila secretes toxins into the host cell that induce the non-canonical processing and activation of the ER stress sensor and transcription factor ATF6 via a mechanism that is distinct from the canonical pathway activated by unfolded protein buildup. The intracellular bacterial pathogen Legionella pneumophila (L.p.) secretes ∼330 effector proteins into the host cell to sculpt an ER-derived replicative niche. We previously reported five L.p. effectors that inhibit IRE1, a key sensor of the homeostatic unfolded protein response (UPR) pathway. In this study, we discovered a subset of L.p. toxins that selectively activate the UPR sensor ATF6, resulting in its cleavage, nuclear translocation, and target gene transcription. In a deviation from the conventional model, this L.p.–dependent activation of ATF6 does not require its transport to the Golgi or its cleavage by the S1P/S2P proteases. We believe that our findings highlight the unique regulatory control that L.p. exerts upon the three UPR sensors and expand the repertoire of bacterial proteins that selectively perturb host homeostatic pathways.
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Affiliation(s)
- Nnejiuwa U Ibe
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA.,George Williams Hooper Foundation, University of California, San Francisco, San Francisco, CA, USA
| | - Advait Subramanian
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA.,George Williams Hooper Foundation, University of California, San Francisco, San Francisco, CA, USA.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Shaeri Mukherjee
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA .,George Williams Hooper Foundation, University of California, San Francisco, San Francisco, CA, USA
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18
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Zhang P, Li S, Zhang T, Cui F, Shi JH, Zhao F, Sheng X. Characterization of Molecular Subtypes in Head and Neck Squamous Cell Carcinoma With Distinct Prognosis and Treatment Responsiveness. Front Cell Dev Biol 2021; 9:711348. [PMID: 34595167 PMCID: PMC8476885 DOI: 10.3389/fcell.2021.711348] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 08/10/2021] [Indexed: 12/20/2022] Open
Abstract
Head and neck squamous cell carcinoma (HNSCC) is one of the most aggressive malignancies with complex phenotypic, etiological, biological, and clinical heterogeneities. Previous studies have proposed different clinically relevant subtypes of HNSCC, but little is known about its corresponding prognosis or suitable treatment strategy. Here, we identified 101 core genes from three prognostic pathways, including mTORC1 signaling, unfold protein response, and UV response UP, in 124 pairs of tumor and matched normal tissues of HNSCC. Moreover, we identified three robust subtypes associated with distinct molecular characteristics and clinical outcomes using consensus clustering based on the gene expression profiles of 944 HNSCC patients from four independent datasets. We then integrated the genomic information of The Cancer Genome Atlas (TCGA) HNSCC cohort to comprehensively evaluate the molecular features of different subtypes and screen for potentially effective therapeutic agents. Cluster 1 had more arrested oncogenic signaling, the highest immune cell infiltration, the highest immunotherapy and chemotherapeutic responsiveness, and the best prognosis. By contrast, Cluster 3 showed more activated oncogenic signaling, the lowest immune cell infiltration, the lowest immunotherapy and chemotherapy responsiveness, and the worst prognosis. Our findings corroborate the molecular diversity of HNSCC tumors and provide a novel classification strategy that may guide for prognosis and treatment allocation.
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Affiliation(s)
- Pei Zhang
- Department of Stomatology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Shue Li
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan, China
| | - Tingting Zhang
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubation), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Fengzhen Cui
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubation), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ji-Hua Shi
- Department of Hepatobiliary and Pancreatic Surgery, Henan Key Laboratory of Digestive Organ Transplantation, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Faming Zhao
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubation), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xia Sheng
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubation), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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19
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Abstract
The past 25 years of genomics research first revealed which genes are encoded by the human genome and then a detailed catalogue of human genome variation associated with many diseases. Despite this, the function of many genes and gene regulatory elements remains poorly characterized, which limits our ability to apply these insights to human disease. The advent of new CRISPR functional genomics tools allows for scalable and multiplexable characterization of genes and gene regulatory elements encoded by the human genome. These approaches promise to reveal mechanisms of gene function and regulation, and to enable exploration of how genes work together to modulate complex phenotypes.
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20
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Lee EJ, Chan P, Chea L, Kim K, Kaufman RJ, Lin JH. ATF6 is required for efficient rhodopsin clearance and retinal homeostasis in the P23H rho retinitis pigmentosa mouse model. Sci Rep 2021; 11:16356. [PMID: 34381136 PMCID: PMC8357971 DOI: 10.1038/s41598-021-95895-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 07/26/2021] [Indexed: 12/21/2022] Open
Abstract
Retinitis Pigmentosa (RP) is a blinding disease that arises from loss of rods and subsequently cones. The P23H rhodopsin knock-in (P23H-KI) mouse develops retinal degeneration that mirrors RP phenotype in patients carrying the orthologous variant. Previously, we found that the P23H rhodopsin protein was degraded in P23H-KI retinas, and the Unfolded Protein Response (UPR) promoted P23H rhodopsin degradation in heterologous cells in vitro. Here, we investigated the role of a UPR regulator gene, activating transcription factor 6 (Atf6), in rhodopsin protein homeostasis in heterozygous P23H rhodopsin (Rho+/P23H) mice. Significantly increased rhodopsin protein levels were found in Atf6-/-Rho+/P23H retinas compared to Atf6+/-Rho+/P23H retinas at early ages (~ P12), while rhodopsin mRNA levels were not different. The IRE1 pathway of the UPR was hyper-activated in young Atf6-/-Rho+/P23H retinas, and photoreceptor layer thickness was unchanged at this early age in Rho+/P23H mice lacking Atf6. By contrast, older Atf6-/-Rho+/P23H mice developed significantly increased retinal degeneration in comparison to Atf6+/-Rho+/P23H mice in all retinal layers, accompanied by reduced rhodopsin protein levels. Our findings demonstrate that Atf6 is required for efficient clearance of rhodopsin protein in rod photoreceptors expressing P23H rhodopsin, and that loss of Atf6 ultimately accelerates retinal degeneration in P23H-KI mice.
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Affiliation(s)
- Eun-Jin Lee
- Department of Ophthalmology, Stanford University, Palo Alto, CA, USA.,Department of Pathology, Stanford University, Palo Alto, CA, USA.,VA Palo Alto Healthcare System, Palo Alto, CA, USA.,USC ROSKI Eye Institute and Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Priscilla Chan
- Department of Neurology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Leon Chea
- Department of Ophthalmology, Stanford University, Palo Alto, CA, USA.,Department of Pathology, Stanford University, Palo Alto, CA, USA.,VA Palo Alto Healthcare System, Palo Alto, CA, USA
| | - Kyle Kim
- Department of Ophthalmology, Stanford University, Palo Alto, CA, USA.,Department of Pathology, Stanford University, Palo Alto, CA, USA.,VA Palo Alto Healthcare System, Palo Alto, CA, USA
| | - Randal J Kaufman
- Degenerative Diseases Program, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Jonathan H Lin
- Department of Ophthalmology, Stanford University, Palo Alto, CA, USA. .,Department of Pathology, Stanford University, Palo Alto, CA, USA. .,VA Palo Alto Healthcare System, Palo Alto, CA, USA. .,School of Medicine, Stanford University, 300 Pasteur Dr. L235, Palo Alto, CA, 94305, USA.
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21
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Almasy KM, Davies JP, Plate L. Comparative Host Interactomes of the SARS-CoV-2 Nonstructural Protein 3 and Human Coronavirus Homologs. Mol Cell Proteomics 2021; 20:100120. [PMID: 34186245 PMCID: PMC8236078 DOI: 10.1016/j.mcpro.2021.100120] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 06/13/2021] [Accepted: 06/22/2021] [Indexed: 01/01/2023] Open
Abstract
Human coronaviruses have become an increasing threat to global health; three highly pathogenic strains have emerged since the early 2000s, including most recently SARS-CoV-2, the cause of COVID-19. A better understanding of the molecular mechanisms of coronavirus pathogenesis is needed, including how these highly virulent strains differ from those that cause milder, common-cold-like disease. While significant progress has been made in understanding how SARS-CoV-2 proteins interact with the host cell, nonstructural protein 3 (nsp3) has largely been omitted from the analyses. Nsp3 is a viral protease with important roles in viral protein biogenesis, replication complex formation, and modulation of host ubiquitinylation and ISGylation. Herein, we use affinity purification-mass spectrometry to study the host-viral protein-protein interactome of nsp3 from five coronavirus strains: pathogenic strains SARS-CoV-2, SARS-CoV, and MERS-CoV; and endemic common-cold strains hCoV-229E and hCoV-OC43. We divide each nsp3 into three fragments and use tandem mass tag technology to directly compare the interactors across the five strains for each fragment. We find that few interactors are common across all variants for a particular fragment, but we identify shared patterns between select variants, such as ribosomal proteins enriched in the N-terminal fragment (nsp3.1) data set for SARS-CoV-2 and SARS-CoV. We also identify unique biological processes enriched for individual homologs, for instance, nuclear protein import for the middle fragment of hCoV-229E, as well as ribosome biogenesis of the MERS nsp3.2 homolog. Lastly, we further investigate the interaction of the SARS-CoV-2 nsp3 N-terminal fragment with ATF6, a regulator of the unfolded protein response. We show that SARS-CoV-2 nsp3.1 directly binds to ATF6 and can suppress the ATF6 stress response. Characterizing the host interactions of nsp3 widens our understanding of how coronaviruses co-opt cellular pathways and presents new avenues for host-targeted antiviral therapeutics.
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Affiliation(s)
- Katherine M Almasy
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA; Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jonathan P Davies
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA; Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA.
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22
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Echavarría-Consuegra L, Cook GM, Busnadiego I, Lefèvre C, Keep S, Brown K, Doyle N, Dowgier G, Franaszek K, Moore NA, Siddell SG, Bickerton E, Hale BG, Firth AE, Brierley I, Irigoyen N. Manipulation of the unfolded protein response: A pharmacological strategy against coronavirus infection. PLoS Pathog 2021; 17:e1009644. [PMID: 34138976 PMCID: PMC8211288 DOI: 10.1371/journal.ppat.1009644] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 05/13/2021] [Indexed: 01/08/2023] Open
Abstract
Coronavirus infection induces the unfolded protein response (UPR), a cellular signalling pathway composed of three branches, triggered by unfolded proteins in the endoplasmic reticulum (ER) due to high ER load. We have used RNA sequencing and ribosome profiling to investigate holistically the transcriptional and translational response to cellular infection by murine hepatitis virus (MHV), often used as a model for the Betacoronavirus genus to which the recently emerged SARS-CoV-2 also belongs. We found the UPR to be amongst the most significantly up-regulated pathways in response to MHV infection. To confirm and extend these observations, we show experimentally the induction of all three branches of the UPR in both MHV- and SARS-CoV-2-infected cells. Over-expression of the SARS-CoV-2 ORF8 or S proteins alone is itself sufficient to induce the UPR. Remarkably, pharmacological inhibition of the UPR greatly reduced the replication of both MHV and SARS-CoV-2, revealing the importance of this pathway for successful coronavirus replication. This was particularly striking when both IRE1α and ATF6 branches of the UPR were inhibited, reducing SARS-CoV-2 virion release (~1,000-fold). Together, these data highlight the UPR as a promising antiviral target to combat coronavirus infection.
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Affiliation(s)
- Liliana Echavarría-Consuegra
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Georgia M. Cook
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Idoia Busnadiego
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Charlotte Lefèvre
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Sarah Keep
- The Pirbright Institute, Woking, Surrey, United Kingdom
| | - Katherine Brown
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Nicole Doyle
- The Pirbright Institute, Woking, Surrey, United Kingdom
| | | | - Krzysztof Franaszek
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Nathan A. Moore
- Department of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | - Stuart G. Siddell
- Department of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | | | - Benjamin G. Hale
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Andrew E. Firth
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Ian Brierley
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Nerea Irigoyen
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
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23
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Maintenance of Endoplasmic Reticulum Protein Homeostasis in Cancer: Friend or Foe. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2021. [PMID: 34050868 DOI: 10.1007/978-3-030-67696-4_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
The endoplasmic reticulum, as the site of synthesis for proteins in the secretory pathway has evolved select machineries to ensure the correct folding and modification of proteins. However, sometimes these quality control mechanisms fail and proteins are misfolded. Other factors, such as nutrient deprivation, hypoxia or an increased demand on protein synthesis can also cause the accumulation of unfolded or misfolded proteins in the endoplasmic reticulum. There are mechanisms that recognise and deal with this accumulation of protein through degradation and/or export. Many diseases are associated with aberrant quality control mechanisms, and among these, cancer has emerged as a group of diseases that rely on endoplasmic reticulum homeostasis to sustain development and growth. The knowledge of how protein quality control operates in cancer has identified opportunities for these pathways to be pharmacologically targeted, which could lead to newer or more effective treatments in the future.
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24
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Small-molecule endoplasmic reticulum proteostasis regulator acts as a broad-spectrum inhibitor of dengue and Zika virus infections. Proc Natl Acad Sci U S A 2021; 118:2012209118. [PMID: 33441483 PMCID: PMC7826409 DOI: 10.1073/pnas.2012209118] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Flaviviruses, including dengue and Zika, are widespread human pathogens; however, no broadly active therapeutics exist to fight infection. Recently, remodeling of endoplasmic reticulum (ER) proteostasis by pharmacologic regulators, such as compound 147, was shown to correct pathologic ER imbalances associated with protein misfolding diseases. Here, we establish an additional activity of compound 147 as an effective host-centered antiviral agent against flaviviruses. Compound 147 reduces infection by attenuating the infectivity of secreted virions without causing toxicity in host cells. Compound 147 is a preferential activator of the ATF6 pathway of the ER unfolded protein response, which requires targeting of cysteine residues primarily on protein disulfide isomerases (PDIs). We find that the antiviral activity of 147 is independent of ATF6 induction but does require modification of reactive thiols on protein targets. Targeting PDIs and additional non-PDI targets using RNAi and other small-molecule inhibitors was unable to recapitulate the antiviral effects, suggesting a unique polypharmacology may mediate the activity. Importantly, 147 can impair infection of multiple strains of dengue and Zika virus, indicating that it is suitable as a broad-spectrum antiviral agent.
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25
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Xue F, Lu J, Buchl SC, Sun L, Shah VH, Malhi H, Maiers JL. Coordinated signaling of activating transcription factor 6α and inositol-requiring enzyme 1α regulates hepatic stellate cell-mediated fibrogenesis in mice. Am J Physiol Gastrointest Liver Physiol 2021; 320:G864-G879. [PMID: 33728997 PMCID: PMC8202196 DOI: 10.1152/ajpgi.00453.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Liver injury and the unfolded protein response (UPR) are tightly linked, but their relationship differs with cell type and injurious stimuli. UPR initiation promotes hepatic stellate cell (HSC) activation and fibrogenesis, but the underlying mechanisms are unclear. Despite the complexity and overlap downstream of UPR transducers inositol-requiring protein 1α (IRE1α), activating transcription factor 6α (ATF6α), and protein kinase RNA-like ER kinase (PERK), previous research in HSCs primarily focused on IRE1α. Here, we investigated the fibrogenic role of ATF6α or PERK in vitro and HSC-specific UPR signaling in vivo. Overexpression of ATF6α, but not the PERK effector activating transcription factor 4 (ATF4), promoted HSC activation and fibrogenic gene transcription in immortalized HSCs. Furthermore, ATF6α inhibition through Ceapin-A7, or Atf6a deletion, disrupted transforming growth factor β (TGFβ)-mediated activation of primary human hepatic stellate cells (hHSCs) or murine hepatic stellate cells (mHSCs), respectively. We investigated the fibrogenic role of ATF6α in vivo through conditional HSC-specific Atf6a deletion. Atf6aHSCΔ/Δ mice displayed reduced fibrosis and HSC activation following bile duct ligation (BDL) or carbon tetrachloride (CCl4)-induced injury. The Atf6aHSCΔ/Δ phenotype differed from HSC-specific Ire1a deletion, as Ire1aHSCΔ/Δ mice showed reduced fibrogenic gene transcription but no changes in fibrosis compared with Ire1afl/fl mice following BDL. Interestingly, ATF6α signaling increased in Ire1aΔ/Δ HSCs, whereas IRE1α signaling was upregulated in Atf6aΔ/Δ HSCs. Finally, we asked whether co-deletion of Atf6a and Ire1a additively limits fibrosis. Unexpectedly, fibrosis worsened in Atf6aHSCΔ/ΔIre1aHSCΔ/Δ mice following BDL, and Atf6aΔ/ΔIre1aΔ/Δ mHSCs showed increased fibrogenic gene transcription. ATF6α and IRE1α individually promote fibrogenic transcription in HSCs, and ATF6α drives fibrogenesis in vivo. Unexpectedly, disruption of both pathways sensitizes the liver to fibrogenesis, suggesting that fine-tuned UPR signaling is critical for regulating HSC activation and fibrogenesis.NEW & NOTEWORTHY ATF6α is a critical driver of hepatic stellate cell (HSC) activation in vitro. HSC-specific deletion of Atf6a limits fibrogenesis in vivo despite increased IRE1α signaling. Conditional deletion of Ire1α from HSCs limits fibrogenic gene transcription without impacting overall fibrosis. This could be due in part to observed upregulation of the ATF6α pathway. Dual loss of Atf6a and Ire1a from HSCs worsens fibrosis in vivo through enhanced HSC activation.
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Affiliation(s)
- Fei Xue
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
| | - Jianwen Lu
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
| | - Samuel C. Buchl
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
| | - Liankang Sun
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
| | - Vijay H. Shah
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
| | - Harmeet Malhi
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
| | - Jessica L. Maiers
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
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26
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Xiong S, Chng WJ, Zhou J. Crosstalk between endoplasmic reticulum stress and oxidative stress: a dynamic duo in multiple myeloma. Cell Mol Life Sci 2021; 78:3883-3906. [PMID: 33599798 PMCID: PMC8106603 DOI: 10.1007/s00018-021-03756-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 12/19/2020] [Accepted: 01/05/2021] [Indexed: 02/07/2023]
Abstract
Under physiological and pathological conditions, cells activate the unfolded protein response (UPR) to deal with the accumulation of unfolded or misfolded proteins in the endoplasmic reticulum. Multiple myeloma (MM) is a hematological malignancy arising from immunoglobulin-secreting plasma cells. MM cells are subject to continual ER stress and highly dependent on the UPR signaling activation due to overproduction of paraproteins. Mounting evidence suggests the close linkage between ER stress and oxidative stress, demonstrated by overlapping signaling pathways and inter-organelle communication pivotal to cell fate decision. Imbalance of intracellular homeostasis can lead to deranged control of cellular functions and engage apoptosis due to mutual activation between ER stress and reactive oxygen species generation through a self-perpetuating cycle. Here, we present accumulating evidence showing the interactive roles of redox homeostasis and proteostasis in MM pathogenesis and drug resistance, which would be helpful in elucidating the still underdefined molecular pathways linking ER stress and oxidative stress in MM. Lastly, we highlight future research directions in the development of anti-myeloma therapy, focusing particularly on targeting redox signaling and ER stress responses.
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Affiliation(s)
- Sinan Xiong
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597, Republic of Singapore
| | - Wee-Joo Chng
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597, Republic of Singapore.
- Centre for Translational Medicine, Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore, 117599, Republic of Singapore.
- Department of Hematology-Oncology, National University Cancer Institute of Singapore (NCIS), The National University Health System (NUHS), 1E, Kent Ridge Road, Singapore, 119228, Republic of Singapore.
| | - Jianbiao Zhou
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597, Republic of Singapore.
- Centre for Translational Medicine, Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore, 117599, Republic of Singapore.
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27
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Almasy KM, Davies JP, Plate L. Comparative host interactomes of the SARS-CoV-2 nonstructural protein 3 and human coronavirus homologs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021:2021.03.08.434440. [PMID: 33758849 PMCID: PMC7987008 DOI: 10.1101/2021.03.08.434440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Human coronaviruses have become an increasing threat to global health; three highly pathogenic strains have emerged since the early 2000s, including most recently SARS-CoV-2, the cause of COVID-19. A better understanding of the molecular mechanisms of coronavirus pathogenesis is needed, including how these highly virulent strains differ from those that cause milder, common-cold like disease. While significant progress has been made in understanding how SARS-CoV-2 proteins interact with the host cell, non-structural protein 3 (nsp3) has largely been omitted from the analyses. Nsp3 is a viral protease with important roles in viral protein biogenesis, replication complex formation, and modulation of host ubiquitinylation and ISGylation. Herein, we use affinity purification-mass spectrometry to study the host-viral protein-protein interactome of nsp3 from five coronavirus strains: pathogenic strains SARS-CoV-2, SARS-CoV, and MERS-CoV; and endemic common-cold strains hCoV-229E and hCoV-OC43. We divide each nsp3 into three fragments and use tandem mass tag technology to directly compare the interactors across the five strains for each fragment. We find that few interactors are common across all variants for a particular fragment, but we identify shared patterns between select variants, such as ribosomal proteins enriched in the N-terminal fragment (nsp3.1) dataset for SARS-CoV-2 and SARS-CoV. We also identify unique biological processes enriched for individual homologs, for instance nuclear protein important for the middle fragment of hCoV-229E, as well as ribosome biogenesis of the MERS nsp3.2 homolog. Lastly, we further investigate the interaction of the SARS-CoV-2 nsp3 N-terminal fragment with ATF6, a regulator of the unfolded protein response. We show that SARS-CoV-2 nsp3.1 directly binds to ATF6 and can suppress the ATF6 stress response. Characterizing the host interactions of nsp3 widens our understanding of how coronaviruses co-opt cellular pathways and presents new avenues for host-targeted antiviral therapeutics.
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Affiliation(s)
- Katherine M. Almasy
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jonathan P. Davies
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
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28
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Rius B, Mesgarzadeh JS, Romine IC, Paxman RJ, Kelly JW, Wiseman RL. Pharmacologic targeting of plasma cell endoplasmic reticulum proteostasis to reduce amyloidogenic light chain secretion. Blood Adv 2021; 5:1037-1049. [PMID: 33599742 PMCID: PMC7903236 DOI: 10.1182/bloodadvances.2020002813] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 01/05/2021] [Indexed: 02/08/2023] Open
Abstract
Light chain (LC) amyloidosis (AL) involves the toxic aggregation of amyloidogenic immunoglobulin LCs secreted from a clonal expansion of diseased plasma cells. Current AL treatments use chemotherapeutics to ablate the AL plasma cell population. However, no treatments are available that directly reduce the toxic LC aggregation involved in AL pathogenesis. An attractive strategy to reduce toxic LC aggregation in AL involves enhancing endoplasmic reticulum (ER) proteostasis in plasma cells to reduce the secretion and subsequent aggregation of amyloidogenic LCs. Here, we show that the ER proteostasis regulator compound 147 reduces secretion of an amyloidogenic LC as aggregation-prone monomers and dimers in AL patient-derived plasma cells. Compound 147 was established to promote ER proteostasis remodeling by activating the ATF6 unfolded protein response signaling pathway through a mechanism involving covalent modification of ER protein disulfide isomerases (PDIs). However, we show that 147-dependent reductions in amyloidogenic LCs are independent of ATF6 activation. Instead, 147 reduces amyloidogenic LC secretion through the selective, on-target covalent modification of ER proteostasis factors, including PDIs, revealing an alternative mechanism by which this compound can influence ER proteostasis of amyloidogenic proteins. Importantly, compound 147 does not interfere with AL plasma cell toxicity induced by bortezomib, a standard chemotherapeutic used to ablate the underlying diseased plasma cells in AL. This shows that pharmacologic targeting of ER proteostasis through selective covalent modification of ER proteostasis factors is a strategy that can be used in combination with chemotherapeutics to reduce the LC toxicity associated with AL pathogenesis.
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Affiliation(s)
| | | | | | | | - Jeffery W Kelly
- Department of Chemistry, and
- Skaggs Institute for Chemical Biology, Scripps Research Institute, La Jolla, CA
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29
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Grandjean JMD, Wiseman RL. Small molecule strategies to harness the unfolded protein response: where do we go from here? J Biol Chem 2020; 295:15692-15711. [PMID: 32887796 PMCID: PMC7667976 DOI: 10.1074/jbc.rev120.010218] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/02/2020] [Indexed: 12/31/2022] Open
Abstract
The unfolded protein response (UPR) plays a central role in regulating endoplasmic reticulum (ER) and global cellular physiology in response to pathologic ER stress. The UPR is comprised of three signaling pathways activated downstream of the ER membrane proteins IRE1, ATF6, and PERK. Once activated, these proteins initiate transcriptional and translational signaling that functions to alleviate ER stress, adapt cellular physiology, and dictate cell fate. Imbalances in UPR signaling are implicated in the pathogenesis of numerous, etiologically-diverse diseases, including many neurodegenerative diseases, protein misfolding diseases, diabetes, ischemic disorders, and cancer. This has led to significant interest in establishing pharmacologic strategies to selectively modulate IRE1, ATF6, or PERK signaling to both ameliorate pathologic imbalances in UPR signaling implicated in these different diseases and define the importance of the UPR in diverse cellular and organismal contexts. Recently, there has been significant progress in the identification and characterization of UPR modulating compounds, providing new opportunities to probe the pathologic and potentially therapeutic implications of UPR signaling in human disease. Here, we describe currently available UPR modulating compounds, specifically highlighting the strategies used for their discovery and specific advantages and disadvantages in their application for probing UPR function. Furthermore, we discuss lessons learned from the application of these compounds in cellular and in vivo models to identify favorable compound properties that can help drive the further translational development of selective UPR modulators for human disease.
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Affiliation(s)
- Julia M D Grandjean
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California, USA
| | - R Luke Wiseman
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California, USA.
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30
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Giadone RM, Liberti DC, Matte TM, Rosarda JD, Torres-Arancivia C, Ghosh S, Diedrich JK, Pankow S, Skvir N, Jean JC, Yates JR, Wilson AA, Connors LH, Kotton DN, Wiseman RL, Murphy GJ. Expression of Amyloidogenic Transthyretin Drives Hepatic Proteostasis Remodeling in an Induced Pluripotent Stem Cell Model of Systemic Amyloid Disease. Stem Cell Reports 2020; 15:515-528. [PMID: 32735824 PMCID: PMC7419739 DOI: 10.1016/j.stemcr.2020.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 07/01/2020] [Accepted: 07/02/2020] [Indexed: 01/15/2023] Open
Abstract
The systemic amyloidoses are diverse disorders in which misfolded proteins are secreted by effector organs and deposited as proteotoxic aggregates at downstream tissues. Although well described clinically, the contribution of synthesizing organs to amyloid disease pathogenesis is unknown. Here, we utilize hereditary transthyretin amyloidosis (ATTR amyloidosis) induced pluripotent stem cells (iPSCs) to define the contribution of hepatocyte-like cells (HLCs) to the proteotoxicity of secreted transthyretin (TTR). To this end, we generated isogenic, patient-specific iPSCs expressing either amyloidogenic or wild-type TTR. We combined this tool with single-cell RNA sequencing to identify hepatic proteostasis factors correlating with destabilized TTR production in iPSC-derived HLCs. By generating an ATF6 inducible patient-specific iPSC line, we demonstrated that enhancing hepatic ER proteostasis preferentially reduces the secretion of amyloidogenic TTR. These data highlight the liver's capacity to chaperone misfolded TTR prior to deposition, and moreover suggest the potential for unfolded protein response modulating therapeutics in the treatment of diverse systemic amyloidoses.
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Affiliation(s)
- Richard M Giadone
- Center for Regenerative Medicine of Boston University and Boston Medical Center, 670 Albany Street, 2nd Floor, Boston, MA 02118, USA
| | - Derek C Liberti
- Center for Regenerative Medicine of Boston University and Boston Medical Center, 670 Albany Street, 2nd Floor, Boston, MA 02118, USA
| | - Taylor M Matte
- Center for Regenerative Medicine of Boston University and Boston Medical Center, 670 Albany Street, 2nd Floor, Boston, MA 02118, USA
| | - Jessica D Rosarda
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Celia Torres-Arancivia
- Alan and Sandra Gerry Amyloid Research Laboratory, Amyloidosis Center, Boston University School of Medicine, Boston, MA, USA
| | - Sabrina Ghosh
- Center for Regenerative Medicine of Boston University and Boston Medical Center, 670 Albany Street, 2nd Floor, Boston, MA 02118, USA
| | - Jolene K Diedrich
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Sandra Pankow
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Nicholas Skvir
- Center for Regenerative Medicine of Boston University and Boston Medical Center, 670 Albany Street, 2nd Floor, Boston, MA 02118, USA
| | - J C Jean
- Center for Regenerative Medicine of Boston University and Boston Medical Center, 670 Albany Street, 2nd Floor, Boston, MA 02118, USA; The Pulmonary Center and Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - John R Yates
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Andrew A Wilson
- Center for Regenerative Medicine of Boston University and Boston Medical Center, 670 Albany Street, 2nd Floor, Boston, MA 02118, USA; The Pulmonary Center and Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Lawreen H Connors
- Alan and Sandra Gerry Amyloid Research Laboratory, Amyloidosis Center, Boston University School of Medicine, Boston, MA, USA
| | - Darrell N Kotton
- Center for Regenerative Medicine of Boston University and Boston Medical Center, 670 Albany Street, 2nd Floor, Boston, MA 02118, USA; The Pulmonary Center and Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - R Luke Wiseman
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - George J Murphy
- Center for Regenerative Medicine of Boston University and Boston Medical Center, 670 Albany Street, 2nd Floor, Boston, MA 02118, USA; Section of Hematology and Oncology, Department of Medicine, Boston University School of Medicine, Boston, MA, USA.
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31
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Silva BSC, DiGiovanni L, Kumar R, Carmichael RE, Kim PK, Schrader M. Maintaining social contacts: The physiological relevance of organelle interactions. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118800. [PMID: 32712071 PMCID: PMC7377706 DOI: 10.1016/j.bbamcr.2020.118800] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/12/2020] [Accepted: 07/19/2020] [Indexed: 02/07/2023]
Abstract
Membrane-bound organelles in eukaryotic cells form an interactive network to coordinate and facilitate cellular functions. The formation of close contacts, termed "membrane contact sites" (MCSs), represents an intriguing strategy for organelle interaction and coordinated interplay. Emerging research is rapidly revealing new details of MCSs. They represent ubiquitous and diverse structures, which are important for many aspects of cell physiology and homeostasis. Here, we provide a comprehensive overview of the physiological relevance of organelle contacts. We focus on mitochondria, peroxisomes, the Golgi complex and the plasma membrane, and discuss the most recent findings on their interactions with other subcellular organelles and their multiple functions, including membrane contacts with the ER, lipid droplets and the endosomal/lysosomal compartment.
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Affiliation(s)
- Beatriz S C Silva
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK
| | - Laura DiGiovanni
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Rechal Kumar
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK
| | - Ruth E Carmichael
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK.
| | - Peter K Kim
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada.
| | - Michael Schrader
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK.
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32
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Chen C, Li J, Qin X, Wang W. Peroxisomal Membrane Contact Sites in Mammalian Cells. Front Cell Dev Biol 2020; 8:512. [PMID: 32714927 PMCID: PMC7344225 DOI: 10.3389/fcell.2020.00512] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Accepted: 05/28/2020] [Indexed: 12/11/2022] Open
Abstract
Peroxisomes participate in essential cellular metabolic processes, such as oxidation of fatty acids (FAs) and maintenance of reactive oxygen species (ROS) homeostasis. Peroxisomes must communicate with surrounding organelles to exchange information and metabolites. The formation of membrane contact sites (MCSs), where protein-protein or protein-lipid complexes tether the opposing membranes of two organelles, represents an essential means of organelle crosstalk. Peroxisomal MCS (PO-MCS) studies are emerging but are still in the early stages. In this review, we summarize the identified PO-MCSs with the ER, mitochondria, lipid droplets, and lysosomes in mammalian cells and discuss their tethering mechanisms and physiological roles. We also highlight several features of PO-MCSs that may help future studies.
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Affiliation(s)
- Chao Chen
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jing Li
- Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xuhui Qin
- Department of Human Anatomy, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Wang
- Department of Human Anatomy, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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33
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Kostic M, Jones LH. Critical Assessment of Targeted Protein Degradation as a Research Tool and Pharmacological Modality. Trends Pharmacol Sci 2020; 41:305-317. [PMID: 32222318 PMCID: PMC7202367 DOI: 10.1016/j.tips.2020.02.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 02/27/2020] [Accepted: 02/28/2020] [Indexed: 02/08/2023]
Abstract
Small molecules continue to dominate drug discovery because of their ease of use, lower cost of manufacturing, and access to intracellular targets. However, despite these advantages, small molecules are more likely to fail in clinical trials compared with biologicals and their development remains limited to a small subset of disease-relevant 'druggable' targets. Targeted protein degradation has recently emerged as a novel pharmacological modality that promises to overcome small molecule limitations whilst retaining their key advantages. Here, we use a Strengths-Weaknesses-Opportunities-Threats (SWOT) framework to critically assess the current status of this rapidly evolving field. We expect that degrader molecules are only the beginning of a range of novel targeting modalities that hijack existing endogenous cellular machineries to chemically redirect biological targets and pathways. Therefore, this piece may offer a roadmap for enhancing development of both degraders and related modalities.
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Affiliation(s)
- Milka Kostic
- Department of Cancer Biology and Chemical Biology Program, Dana-Farber Cancer Institute, 450 Brookline Ave, Boston, MA 02215, USA.
| | - Lyn H Jones
- Center for Protein Degradation, Dana-Farber Cancer Institute, 360 Longwood Ave, Boston, MA 02215, USA.
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Abstract
Protein folding in the cell is mediated by an extensive network of >1,000 chaperones, quality control factors, and trafficking mechanisms collectively termed the proteostasis network. While the components and organization of this network are generally well established, our understanding of how protein-folding problems are identified, how the network components integrate to successfully address challenges, and what types of biophysical issues each proteostasis network component is capable of addressing remains immature. We describe a chemical biology-informed framework for studying cellular proteostasis that relies on selection of interesting protein-folding problems and precise researcher control of proteostasis network composition and activities. By combining these methods with multifaceted strategies to monitor protein folding, degradation, trafficking, and aggregation in cells, researchers continue to rapidly generate new insights into cellular proteostasis.
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Affiliation(s)
- Rebecca M Sebastian
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA;
| | - Matthew D Shoulders
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA;
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35
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Staying in Healthy Contact: How Peroxisomes Interact with Other Cell Organelles. Trends Mol Med 2019; 26:201-214. [PMID: 31727543 DOI: 10.1016/j.molmed.2019.09.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/24/2019] [Accepted: 09/24/2019] [Indexed: 11/24/2022]
Abstract
Peroxisomes share extensive metabolic connections with other cell organelles. Membrane contact sites (MCSs) establish and maintain such interactions, and they are vital for organelle positioning and motility. In the past few years peroxisome interactions and MCSs with other cellular organelles have been explored extensively, resulting in the identification of new MCSs, the tethering molecules involved, and their functional characterization. Defective tethering and compartmental communication can lead to pathological conditions that can be termed 'organelle interaction diseases'. We review peroxisome-organelle interactions in mammals and summarize the most recent knowledge of mammalian peroxisomal organelle contacts in health and disease.
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36
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Karagöz GE, Aragón T, Acosta-Alvear D. Recent advances in signal integration mechanisms in the unfolded protein response. F1000Res 2019; 8. [PMID: 31723416 PMCID: PMC6833987 DOI: 10.12688/f1000research.19848.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/22/2019] [Indexed: 12/15/2022] Open
Abstract
Since its discovery more than 25 years ago, great progress has been made in our understanding of the unfolded protein response (UPR), a homeostatic mechanism that adjusts endoplasmic reticulum (ER) function to satisfy the physiological demands of the cell. However, if ER homeostasis is unattainable, the UPR switches to drive cell death to remove defective cells in an effort to protect the health of the organism. This functional dichotomy places the UPR at the crossroads of the adaptation versus apoptosis decision. Here, we focus on new developments in UPR signaling mechanisms, in the interconnectivity among the signaling pathways that make up the UPR in higher eukaryotes, and in the coordination between the UPR and other fundamental cellular processes.
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Affiliation(s)
- G Elif Karagöz
- Max Perutz Labs Vienna, Medical University of Vienna, Vienna, Austria
| | - Tomás Aragón
- Department of Gene Therapy and Regulation of Gene Expression, University of Navarra, Pamplona, Spain
| | - Diego Acosta-Alvear
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, Santa Barbara, CA, USA
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