1
|
Kalinin A, Zubkova E, Menshikov M. Integrated Stress Response (ISR) Pathway: Unraveling Its Role in Cellular Senescence. Int J Mol Sci 2023; 24:17423. [PMID: 38139251 PMCID: PMC10743681 DOI: 10.3390/ijms242417423] [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: 11/02/2023] [Revised: 12/11/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
Cellular senescence is a complex process characterized by irreversible cell cycle arrest. Senescent cells accumulate with age, promoting disease development, yet the absence of specific markers hampers the development of selective anti-senescence drugs. The integrated stress response (ISR), an evolutionarily highly conserved signaling network activated in response to stress, globally downregulates protein translation while initiating the translation of specific protein sets including transcription factors. We propose that ISR signaling plays a central role in controlling senescence, given that senescence is considered a form of cellular stress. Exploring the intricate relationship between the ISR pathway and cellular senescence, we emphasize its potential as a regulatory mechanism in senescence and cellular metabolism. The ISR emerges as a master regulator of cellular metabolism during stress, activating autophagy and the mitochondrial unfolded protein response, crucial for maintaining mitochondrial quality and efficiency. Our review comprehensively examines ISR molecular mechanisms, focusing on ATF4-interacting partners, ISR modulators, and their impact on senescence-related conditions. By shedding light on the intricate relationship between ISR and cellular senescence, we aim to inspire future research directions and advance the development of targeted anti-senescence therapies based on ISR modulation.
Collapse
Affiliation(s)
- Alexander Kalinin
- National Medical Research Centre of Cardiology Named after Academician E.I. Chazov, 121552 Moscow, Russia; (A.K.); (E.Z.)
- Faculty of Fundamental Medicine, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Ekaterina Zubkova
- National Medical Research Centre of Cardiology Named after Academician E.I. Chazov, 121552 Moscow, Russia; (A.K.); (E.Z.)
| | - Mikhail Menshikov
- National Medical Research Centre of Cardiology Named after Academician E.I. Chazov, 121552 Moscow, Russia; (A.K.); (E.Z.)
| |
Collapse
|
2
|
Payea MJ, Dar SA, Anerillas CA, Martindale JL, Belair C, Munk R, Malla S, Fan J, Piao Y, Yang X, Rehman A, Banskota N, Abdelmohsen K, Gorospe M, Maragkakis M. Senescence suppresses the integrated stress response and activates a stress-enhanced secretory phenotype. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.12.536613. [PMID: 37609272 PMCID: PMC10441410 DOI: 10.1101/2023.04.12.536613] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Senescence is a state of indefinite cell cycle arrest associated with aging, cancer, and age-related diseases. Here, using label-based mass spectrometry, ribosome profiling and nanopore direct RNA sequencing, we explore the coordinated interaction of translational and transcriptional programs of human cellular senescence. We find that translational deregulation and a corresponding maladaptive integrated stress response (ISR) is a hallmark of senescence that desensitizes senescent cells to stress. We present evidence that senescent cells maintain high levels of eIF2α phosphorylation, typical of ISR activation, but translationally repress production of the stress response transcription factor 4 (ATF4) by ineffective bypass of the inhibitory upstream open reading frames. Surprisingly, ATF4 translation remains inhibited even after acute proteotoxic and amino acid starvation stressors, resulting in a highly diminished stress response. Furthermore, absent a response, stress augments the senescence secretory phenotype, thus intensifying a proinflammatory state that exacerbates disease. Our results reveal a novel mechanism that senescent cells exploit to evade an adaptive stress response and remain viable.
Collapse
|
3
|
Wek RC, Anthony TG, Staschke KA. Surviving and Adapting to Stress: Translational Control and the Integrated Stress Response. Antioxid Redox Signal 2023; 39:351-373. [PMID: 36943285 PMCID: PMC10443206 DOI: 10.1089/ars.2022.0123] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 02/16/2023] [Accepted: 02/20/2023] [Indexed: 03/23/2023]
Abstract
Significance: Organisms adapt to changing environments by engaging cellular stress response pathways that serve to restore proteostasis and enhance survival. A primary adaptive mechanism is the integrated stress response (ISR), which features phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (eIF2). Four eIF2α kinases respond to different stresses, enabling cells to rapidly control translation to optimize management of resources and reprogram gene expression for stress adaptation. Phosphorylation of eIF2 blocks its guanine nucleotide exchange factor, eIF2B, thus lowering the levels of eIF2 bound to GTP that is required to deliver initiator transfer RNA (tRNA) to ribosomes. While bulk messenger RNA (mRNA) translation can be sharply lowered by heightened phosphorylation of eIF2α, there are other gene transcripts whose translation is unchanged or preferentially translated. Among the preferentially translated genes is ATF4, which directs transcription of adaptive genes in the ISR. Recent Advances and Critical Issues: This review focuses on how eIF2α kinases function as first responders of stress, the mechanisms by which eIF2α phosphorylation and other stress signals regulate the exchange activity of eIF2B, and the processes by which the ISR triggers differential mRNA translation. To illustrate the synergy between stress pathways, we describe the mechanisms and functional significance of communication between the ISR and another key regulator of translation, mammalian/mechanistic target of rapamycin complex 1 (mTORC1), during acute and chronic amino acid insufficiency. Finally, we discuss the pathological conditions that stem from aberrant regulation of the ISR, as well as therapeutic strategies targeting the ISR to alleviate disease. Future Directions: Important topics for future ISR research are strategies for modulating this stress pathway in disease conditions and drug development, molecular processes for differential translation and the coordinate regulation of GCN2 and other stress pathways during physiological and pathological conditions. Antioxid. Redox Signal. 39, 351-373.
Collapse
Affiliation(s)
- Ronald C. Wek
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, USA
| | - Tracy G. Anthony
- Department of Nutritional Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Kirk A. Staschke
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, USA
| |
Collapse
|
4
|
Takahashi M, Okamoto Y, Kato Y, Shirahama H, Tsukahara S, Sugimoto Y, Tomida A. Activating mutations in EGFR and PI3K promote ATF4 induction for NSCLC cell survival during amino acid deprivation. Heliyon 2023; 9:e14799. [PMID: 37025861 PMCID: PMC10070656 DOI: 10.1016/j.heliyon.2023.e14799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 03/17/2023] [Accepted: 03/17/2023] [Indexed: 03/29/2023] Open
Abstract
Some oncoproteins along with stress kinase general control non-derepressible 2 (GCN2) can ensure the induction of activating transcription factor 4 (ATF4) to counteract amino acid deprivation; however, little is known regarding the role of the oncogenic EGFR-PI3K pathway. In this study, we demonstrate that both mutated EGFR and PIK3CA contribute to ATF4 induction following GCN2 activation in NSCLC cells. The inhibition of EGFR or PI3K mutant proteins, pharmacologically or through genetic knockdown, inhibited ATF4 induction without affecting GCN2 activation. A downstream analysis revealed that the oncogenic EGFR-PI3K pathway may utilize mTOR-mediated translation control mechanisms for ATF4 induction. Furthermore, in NSCLC cells harboring co-mutations in EGFR and PIK3CA, the combined inhibition of these oncoproteins markedly suppressed ATF4 induction and the subsequent gene expression program as well as cell viability during amino acid deprivation. Our findings establish a role for the oncogenic EGFR-PI3K pathway in the adaptive stress response and provide a strategy to improve EGFR-targeted NSCLC therapy.
Collapse
|
5
|
Yamada Y, Saito H, Araki M, Tsuchimoto Y, Muroi SI, Suzuki K, Toume K, Kim JD, Matsuzaka T, Sone H, Shimano H, Nakagawa Y. Wogonin, a Compound in Scutellaria baicalensis, Activates ATF4–FGF21 Signaling in Mouse Hepatocyte AML12 Cells. Nutrients 2022; 14:nu14193920. [PMID: 36235573 PMCID: PMC9572861 DOI: 10.3390/nu14193920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/13/2022] [Accepted: 09/17/2022] [Indexed: 11/29/2022] Open
Abstract
Fibroblast growth factor 21 (FGF21), which is mainly synthesized and secreted by the liver, plays a crucial role in systemic glucose and lipid metabolism, ameliorating metabolic diseases. In this study, we screened the WAKANYAKU library derived from medicinal herbs to identify compounds that can activate Fgf21 expression in mouse hepatocyte AML12 cells. We identified Scutellaria baicalensis root extract and one of its components, wogonin, as an activator of Fgf21 expression. Wogonin also enhanced the expression of activating transcription factor 4 (ATF4) by a mechanism other than ER stress. Knockdown of ATF4 by siRNA suppressed wogonin-induced Fgf21 expression, highlighting its essential role in wogonin’s mode of action. Thus, our results indicate that wogonin would be a strong candidate for a therapeutic to improve metabolic diseases by enhancing hepatic FGF21 production.
Collapse
Affiliation(s)
- Yasunari Yamada
- Division of Complex Biosystem Research, Department of Research and Development, Institute of Natural Medicine, University of Toyama, Toyama 930-0194, Japan
| | - Hodaka Saito
- Division of Complex Biosystem Research, Department of Research and Development, Institute of Natural Medicine, University of Toyama, Toyama 930-0194, Japan
| | - Masaya Araki
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan
| | - Yuhei Tsuchimoto
- Division of Complex Biosystem Research, Department of Research and Development, Institute of Natural Medicine, University of Toyama, Toyama 930-0194, Japan
| | - Shin-ichi Muroi
- Division of Complex Biosystem Research, Department of Research and Development, Institute of Natural Medicine, University of Toyama, Toyama 930-0194, Japan
| | - Kyohei Suzuki
- Division of Complex Biosystem Research, Department of Research and Development, Institute of Natural Medicine, University of Toyama, Toyama 930-0194, Japan
| | - Kazufumi Toume
- Section of Pharmacognosy, Institute of Natural Medicine, University of Toyama, Toyama 930-0194, Japan
| | - Jun-Dal Kim
- Division of Complex Biosystem Research, Department of Research and Development, Institute of Natural Medicine, University of Toyama, Toyama 930-0194, Japan
- Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba 305-8577, Japan
| | - Takashi Matsuzaka
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan
- Transborder Medical Research Center (TMRC), University of Tsukuba, Tsukuba 305-8575, Japan
| | - Hirohito Sone
- Department of Hematology, Endocrinology and Metabolism, Niigata University Faculty of Medicine, Niigata 951-8510, Japan
| | - Hitoshi Shimano
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan
- Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba 305-8577, Japan
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba 305-8575, Japan
| | - Yoshimi Nakagawa
- Division of Complex Biosystem Research, Department of Research and Development, Institute of Natural Medicine, University of Toyama, Toyama 930-0194, Japan
- Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba 305-8577, Japan
- Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Tokyo 100-0004, Japan
- Correspondence: ; Tel.: +81-76-434-7610
| |
Collapse
|
6
|
Staklinski SJ, Chang MC, Yu F, Collins Ruff K, Franz DN, Qian Z, Bloom LB, Merritt ME, McKenna R, Kilberg MS. Cellular and molecular characterization of two novel asparagine synthetase gene mutations linked to asparagine synthetase deficiency. J Biol Chem 2022; 298:102385. [PMID: 35985424 PMCID: PMC9478401 DOI: 10.1016/j.jbc.2022.102385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 08/04/2022] [Accepted: 08/05/2022] [Indexed: 11/22/2022] Open
Abstract
Asparagine synthetase (ASNS) catalyzes synthesis of asparagine (Asn) and Glu from Asp and Gln in an ATP-dependent reaction. Asparagine synthetase deficiency (ASNSD) results from biallelic mutations in the ASNS gene. Affected children exhibit congenital microcephaly, continued brain atrophy, seizures, and often premature mortality. However, the underlying mechanisms are unclear. This report describes a compound heterozygotic ASNSD child with two novel mutations in the ASNS gene, c.1118G>T (paternal) and c.1556G>A (maternal), that lead to G373V or R519H ASNS variants. Structural mapping suggested that neither variant participates directly in catalysis. Growth of cultured fibroblasts from either parent was unaffected in Asn-free medium, whereas growth of the child's cells was suppressed by about 50%. Analysis of Asn levels unexpectedly revealed that extracellular rather than intracellular Asn correlated with the reduced proliferation during incubation of the child's cells in Asn-free medium. Our attempts to ectopically express the G373V variant in either HEK293T or JRS cells resulted in minimal protein production, suggesting instability. Protein expression and purification from HEK293T cells revealed reduced activity for the R519H variant relative to WT ASNS. Expression of WT ASNS in ASNS-null JRS cells resulted in nearly complete rescue of growth in Asn-free medium, whereas we observed no proliferation for the cells expressing either the G373V or R519H variant. These results support the conclusion that the coexpression of the G373V and R519H ASNS variants leads to significantly reduced Asn synthesis, which negatively impacts cellular growth. These observations are consistent with the ASNSD phenotype.
Collapse
Affiliation(s)
- Stephen J Staklinski
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Mario C Chang
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Fang Yu
- Department of Medicine, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Kathleen Collins Ruff
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - David N Franz
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Zhijian Qian
- Department of Medicine, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Linda B Bloom
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Robert McKenna
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Michael S Kilberg
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, USA.
| |
Collapse
|
7
|
Sawa R, Ohnishi A, Ohno M, Nagata M, Wake I, Okimura Y. Specific amino acids regulate Sestrin2 mRNA and protein levels in an ATF4-dependent manner in C2C12 myocytes. Biochim Biophys Acta Gen Subj 2022; 1866:130174. [PMID: 35597502 DOI: 10.1016/j.bbagen.2022.130174] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 04/29/2022] [Accepted: 05/16/2022] [Indexed: 10/18/2022]
Abstract
BACKGROUND Sestrin2 is a conserved protein in several species, and its expression is upregulated in cells under various environmental stresses. Sestrin2 content is involved in the function of mechanistic target of rapamycin complex 1 (mTORC1) in mouse embryonic fibroblasts and C2C12 cells. METHODS C2C12 cells were treated with amino acid-free DMEM (AF-DMEM) for 5 h. The effects of the addition of specific amino acids to AF-DMEM on Sestrin2 mRNA and protein expression were examined using RT-qPCR and western blotting, respectively. The mechanism by which amino acids regulate Sestrin2 mRNA expression was examined using blocking and siRNA experiments. RESULTS AF-DMEM increased the mRNA and protein levels of both Sestrin2 and activating transcription factor 4 (ATF4). The addition of a specific amino acid changed Sestrin2 mRNA and protein levels. The response pattern of Sestrin2 to specific amino acids was similar to that of ATF4. ATF4 siRNA reduced Sestrin2 mRNA levels. AF-DMEM increased eukaryotic initiation factor 2α (eIF2α) phosphorylation as early as 10 min after the treatment; however, ATF4 and Sestrin2 were increased 300 min after the treatment. Nuclear factor erythroid 2-related factor 2 and pancreatic and duodenal homeobox 1 siRNA did not affect ATF4 and Sestrin2 mRNA expression. CONCLUSIONS Specific Amino acids regulate Sestrin2 levels in an ATF4-dependent manner in C2C12 cells. GENERAL SIGNIFICANCE The results of the present study indicate that amino acids regulate levels of Sestrin2, which might cause phenotypic alterations, including mTORC1 activity, in C2C12 cells.
Collapse
Affiliation(s)
- Ran Sawa
- Department of Nutrition and Food Science, Kobe Women's University Graduate School of Life Sciences, 2-1 Higashisuma-aoyama, Suma-ku, Kobe 654-8585, Japan
| | - Ayaka Ohnishi
- Department of Nutrition and Food Science, Kobe Women's University Graduate School of Life Sciences, 2-1 Higashisuma-aoyama, Suma-ku, Kobe 654-8585, Japan
| | - Maya Ohno
- Department of Nutrition and Food Science, Kobe Women's University Graduate School of Life Sciences, 2-1 Higashisuma-aoyama, Suma-ku, Kobe 654-8585, Japan
| | - Maika Nagata
- Department of Nutrition and Food Science, Kobe Women's University Graduate School of Life Sciences, 2-1 Higashisuma-aoyama, Suma-ku, Kobe 654-8585, Japan
| | - Ikumi Wake
- Department of Nutrition and Food Science, Kobe Women's University Graduate School of Life Sciences, 2-1 Higashisuma-aoyama, Suma-ku, Kobe 654-8585, Japan
| | - Yasuhiko Okimura
- Department of Nutrition and Food Science, Kobe Women's University Graduate School of Life Sciences, 2-1 Higashisuma-aoyama, Suma-ku, Kobe 654-8585, Japan.
| |
Collapse
|
8
|
Lee DM, Seo MJ, Lee HJ, Jin HJ, Choi KS. ISRIB plus bortezomib triggers paraptosis in breast cancer cells via enhanced translation and subsequent proteotoxic stress. Biochem Biophys Res Commun 2022; 596:56-62. [PMID: 35114585 DOI: 10.1016/j.bbrc.2022.01.082] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 01/22/2022] [Indexed: 12/29/2022]
Abstract
Despite the success of proteasome inhibitors (PIs) in treating hematopoietic malignancies, including multiple myeloma (MM), their clinical efficacy is limited in solid tumors. In this study, we investigated the involvement of the integrated stress response (ISR), a central cellular adaptive program that responds to proteostatic defects by tuning protein synthesis rates, in determining the fates of cells treated with PI, bortezomib (Bz). We found that Bz induces ISR, and this can be reversed by ISRIB, a small molecule that restores eIF2B-mediated translation during ISR, in both Bz-sensitive MM cells and Bz-insensitive breast cancer cells. Interestingly, while ISRIB protected MM cells from Bz-induced apoptosis, it enhanced Bz sensitivity in breast cancer cells by inducing paraptosis, the cell death mode that is accompanied by dilation of the endoplasmic reticulum (ER) and mitochondria. Combined treatment with ISRIB and Bz may shift the fate of Bz-insensitive cancer cells toward paraptosis by inducing translational rescue, leading to irresolvable proteotoxic stress.
Collapse
Affiliation(s)
- Dong Min Lee
- Department of Biochemistry, Ajou University School of Medicine, Suwon, South Korea
| | - Min Ji Seo
- Department of Biochemistry, Ajou University School of Medicine, Suwon, South Korea
| | - Hong Jae Lee
- Department of Biochemistry, Ajou University School of Medicine, Suwon, South Korea
| | - Hyo Joon Jin
- Department of Biochemistry, Ajou University School of Medicine, Suwon, South Korea
| | - Kyeong Sook Choi
- Department of Biochemistry, Ajou University School of Medicine, Suwon, South Korea.
| |
Collapse
|
9
|
Bahamondes Lorca VA, Bastidas Mayorga BD, Tong L, Wu S. UVB-induced eIF2α phosphorylation in keratinocytes depends on decreased ATF4, GADD34 and CReP expression levels. Life Sci 2021; 286:120044. [PMID: 34637792 DOI: 10.1016/j.lfs.2021.120044] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 10/05/2021] [Accepted: 10/06/2021] [Indexed: 02/05/2023]
Abstract
AIM To elucidate the mechanism behind the sustained high levels of phosphorylated eIF2α in HaCaT cells post-UVB. MAIN METHODS In this study, expression levels of the machinery involved in the dephosphorylation of eIF2α (GADD34, CReP and PP1), as well as the PERK-eIF2α-ATF4-CHOP, IRE1α/XBP1s and ATF6α signaling cascades, were analyzed by western blot and fluorescence microscope. KEY FINDINGS Our data showed that UVB induces the phosphorylation of eIF2α, which induces the translation of ATF4 and consequently the expression of CHOP and GADD34. Nevertheless, UVB also suppresses the translation of ATF4 and GADD34 in HaCaT cells via a p-eIF2α independent mechanism. Therefore, the lack of ATF4, GADD34 and CReP is responsible for the sustained phosphorylation of eIF2α. Finally, our data also showed that UVB selectively modifies PERK and downregulates ATF6α expression but does not induce activation of the IRE1α/XBP1s pathway in HaCaT cells. SIGNIFICANCE Novel mechanism to explain the prolonged phosphorylation of eIF2α post-UVB irradiation.
Collapse
Affiliation(s)
- Verónica A Bahamondes Lorca
- Edison Biotechnology Institute, Ohio University, Athens, OH 45701, USA; Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA; Departamento de Tecnología Médica, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Bernardo D Bastidas Mayorga
- Edison Biotechnology Institute, Ohio University, Athens, OH 45701, USA; Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA
| | - Lingying Tong
- Edison Biotechnology Institute, Ohio University, Athens, OH 45701, USA; Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA.
| | - Shiyong Wu
- Edison Biotechnology Institute, Ohio University, Athens, OH 45701, USA; Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA.
| |
Collapse
|
10
|
Kaspar S, Oertlin C, Szczepanowska K, Kukat A, Senft K, Lucas C, Brodesser S, Hatzoglou M, Larsson O, Topisirovic I, Trifunovic A. Adaptation to mitochondrial stress requires CHOP-directed tuning of ISR. SCIENCE ADVANCES 2021; 7:eabf0971. [PMID: 34039602 PMCID: PMC8153728 DOI: 10.1126/sciadv.abf0971] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 04/07/2021] [Indexed: 05/03/2023]
Abstract
In response to disturbed mitochondrial gene expression and protein synthesis, an adaptive transcriptional response sharing a signature of the integrated stress response (ISR) is activated. We report an intricate interplay between three transcription factors regulating the mitochondrial stress response: CHOP, C/EBPβ, and ATF4. We show that CHOP acts as a rheostat that attenuates prolonged ISR, prevents unfavorable metabolic alterations, and postpones the onset of mitochondrial cardiomyopathy. Upon mitochondrial dysfunction, CHOP interaction with C/EBPβ is needed to adjust ATF4 levels, thus preventing overactivation of the ATF4-regulated transcriptional program. Failure of this interaction switches ISR from an acute to a chronic state, leading to early respiratory chain deficiency, energy crisis, and premature death. Therefore, contrary to its previously proposed role as a transcriptional activator of mitochondrial unfolded protein response, our results highlight a role of CHOP in the fine-tuning of mitochondrial ISR in mammals.
Collapse
Affiliation(s)
- Sophie Kaspar
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD), Medical Faculty, University of Cologne, D-50931 Cologne, Germany
- Institute for Mitochondrial Diseases and Ageing, Medical Faculty and Center for Molecular Medicine Cologne (CMMC) , University of Cologne, D-50931 Cologne, Germany
| | - Christian Oertlin
- Department of Oncology-Pathology, Science for Life Laboratory, Karolinska Institute, Stockholm, Sweden
| | - Karolina Szczepanowska
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD), Medical Faculty, University of Cologne, D-50931 Cologne, Germany
- Institute for Mitochondrial Diseases and Ageing, Medical Faculty and Center for Molecular Medicine Cologne (CMMC) , University of Cologne, D-50931 Cologne, Germany
| | - Alexandra Kukat
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD), Medical Faculty, University of Cologne, D-50931 Cologne, Germany
- Institute for Mitochondrial Diseases and Ageing, Medical Faculty and Center for Molecular Medicine Cologne (CMMC) , University of Cologne, D-50931 Cologne, Germany
| | - Katharina Senft
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD), Medical Faculty, University of Cologne, D-50931 Cologne, Germany
- Institute for Mitochondrial Diseases and Ageing, Medical Faculty and Center for Molecular Medicine Cologne (CMMC) , University of Cologne, D-50931 Cologne, Germany
| | - Christina Lucas
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD), Medical Faculty, University of Cologne, D-50931 Cologne, Germany
| | - Susanne Brodesser
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD), Medical Faculty, University of Cologne, D-50931 Cologne, Germany
| | - Maria Hatzoglou
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ola Larsson
- Department of Oncology-Pathology, Science for Life Laboratory, Karolinska Institute, Stockholm, Sweden
| | - Ivan Topisirovic
- Lady Davis Institute, SMBD Jewish General Hospital, Gerald Bronfman Department of Oncology and Departments of Experimental Medicine and Biochemistry, McGill University, Montreal, Canada
| | - Aleksandra Trifunovic
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD), Medical Faculty, University of Cologne, D-50931 Cologne, Germany.
- Institute for Mitochondrial Diseases and Ageing, Medical Faculty and Center for Molecular Medicine Cologne (CMMC) , University of Cologne, D-50931 Cologne, Germany
| |
Collapse
|
11
|
Kitajima S, Sun W, Lee KL, Ho JC, Oyadomari S, Okamoto T, Masai H, Poellinger L, Kato H. A KDM6 inhibitor potently induces ATF4 and its target gene expression through HRI activation and by UTX inhibition. Sci Rep 2021; 11:4538. [PMID: 33633164 PMCID: PMC7907191 DOI: 10.1038/s41598-021-83857-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 02/01/2021] [Indexed: 01/31/2023] Open
Abstract
UTX/KDM6A encodes a major histone H3 lysine 27 (H3K27) demethylase, and is frequently mutated in various types of human cancers. Although UTX appears to play a crucial role in oncogenesis, the mechanisms involved are still largely unknown. Here we show that a specific pharmacological inhibitor of H3K27 demethylases, GSK-J4, induces the expression of transcription activating factor 4 (ATF4) protein as well as the ATF4 target genes (e.g. PCK2, CHOP, REDD1, CHAC1 and TRIB3). ATF4 induction by GSK-J4 was due to neither transcriptional nor post-translational regulation. In support of this view, the ATF4 induction was almost exclusively dependent on the heme-regulated eIF2α kinase (HRI) in mouse embryonic fibroblasts (MEFs). Gene expression profiles with UTX disruption by CRISPR-Cas9 editing and the following stable re-expression of UTX showed that UTX specifically suppresses the expression of the ATF4 target genes, suggesting that UTX inhibition is at least partially responsible for the ATF4 induction. Apoptosis induction by GSK-J4 was partially and cell-type specifically correlated with the activation of ATF4-CHOP. These findings highlight that the anti-cancer drug candidate GSK-J4 strongly induces ATF4 and its target genes via HRI activation and raise a possibility that UTX might modulate cancer formation by regulating the HRI-ATF4 axis.
Collapse
Affiliation(s)
- Shojiro Kitajima
- grid.4280.e0000 0001 2180 6431Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore, 117599 Republic of Singapore ,grid.26091.3c0000 0004 1936 9959Institute for Advanced Biosciences, Keio University, Kakuganji 246-2, Mizukami, Tsuruoka, Yamagata 997-0052 Japan
| | - Wendi Sun
- grid.4280.e0000 0001 2180 6431Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore, 117599 Republic of Singapore
| | - Kian Leong Lee
- grid.4280.e0000 0001 2180 6431Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore, 117599 Republic of Singapore ,grid.428397.30000 0004 0385 0924Cancer & Stem Cell Biology Programme, Duke-NUS Medical School, 8 College Road, Singapore, 169857 Republic of Singapore
| | - Jolene Caifeng Ho
- grid.4280.e0000 0001 2180 6431Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore, 117599 Republic of Singapore
| | - Seiichi Oyadomari
- grid.267335.60000 0001 1092 3579Institute of Advanced Medical Sciences, Tokushima University, Tokushima, 770-8503 Japan
| | - Takashi Okamoto
- grid.260433.00000 0001 0728 1069Department of Molecular and Cellular Biology, Nagoya City University Graduate School of Medical Science, Mizuho-ku, Nagoya, 467-8601 Japan
| | - Hisao Masai
- grid.272456.0Genome Dynamics Project, Department of Basic Medical Sciences, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506 Japan
| | - Lorenz Poellinger
- grid.4280.e0000 0001 2180 6431Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore, 117599 Republic of Singapore ,Department of Cell and Molecular Biology, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Hiroyuki Kato
- grid.4280.e0000 0001 2180 6431Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore, 117599 Republic of Singapore ,grid.260433.00000 0001 0728 1069Department of Molecular and Cellular Biology, Nagoya City University Graduate School of Medical Science, Mizuho-ku, Nagoya, 467-8601 Japan ,grid.272456.0Genome Dynamics Project, Department of Basic Medical Sciences, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506 Japan
| |
Collapse
|
12
|
Dymkowska D. The involvement of autophagy in the maintenance of endothelial homeostasis: The role of mitochondria. Mitochondrion 2021; 57:131-147. [PMID: 33412335 DOI: 10.1016/j.mito.2020.12.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/22/2020] [Accepted: 12/30/2020] [Indexed: 02/06/2023]
Abstract
Endothelial mitochondria play important signaling roles critical for the regulation of various cellular processes, including calcium signaling, ROS generation, NO synthesis or inflammatory response. Mitochondrial stress or disturbances in mitochondrial function may participate in the development and/or progression of endothelial dysfunction and could precede vascular diseases. Vascular functions are also strictly regulated by properly functioning degradation machinery, including autophagy and mitophagy, and tightly coordinated by mitochondrial and endoplasmic reticulum responses to stress. Within this review, current knowledge related to the development of cardiovascular disorders and the importance of mitochondria, endoplasmic reticulum and degradation mechanisms in vascular endothelial functions are summarized.
Collapse
Affiliation(s)
- Dorota Dymkowska
- The Laboratory of Cellular Metabolism, Nencki Institute of Experimental Biology PAS, 3 Pasteur str. 02-093 Warsaw, Poland.
| |
Collapse
|
13
|
Ceder MM, Lekholm E, Klaesson A, Tripathi R, Schweizer N, Weldai L, Patil S, Fredriksson R. Glucose Availability Alters Gene and Protein Expression of Several Newly Classified and Putative Solute Carriers in Mice Cortex Cell Culture and D. melanogaster. Front Cell Dev Biol 2020; 8:579. [PMID: 32733888 PMCID: PMC7358622 DOI: 10.3389/fcell.2020.00579] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 06/15/2020] [Indexed: 12/16/2022] Open
Abstract
Many newly identified solute carriers (SLCs) and putative transporters have the possibility to be intricately involved in glucose metabolism. Here we show that many transporters of this type display a high degree of regulation at both mRNA and protein level following no or low glucose availability in mouse cortex cultures. We show that this is also the case in Drosophila melanogaster subjected to starvation or diets with different sugar content. Interestingly, re-introduction of glucose to media, or refeeding flies, normalized the gene expression of a number of the targets, indicating a fast and highly dynamic control. Our findings demonstrate high conservation of these transporters and how dependent both cell cultures and organisms are on gene and protein regulation during metabolic fluctuations. Several transporter genes were regulated simultaneously maybe to initiate alternative metabolic pathways as a response to low glucose levels, both in the cell cultures and in D. melanogaster. Our results display that newly identified SLCs of Major Facilitator Superfamily type, as well as the putative transporters included in our study, are regulated by glucose availability and could be involved in several cellular aspects dependent of glucose and/or its metabolites. Recently, a correlation between dysregulation of glucose in the central nervous system and numerous diseases such as obesity, type 2 diabetes mellitus as well as neurological disease such as Alzheimer’s and Parkinson’s diseases indicate a complex regulation and fine tuning of glucose levels in the brain. The fact that almost one third of transporters and transporter-related proteins remain orphans with unknown or contradictive substrate profile, location and function, pinpoint the need for further research about them to fully understand their mechanistic role and their impact on cellular metabolism.
Collapse
Affiliation(s)
- Mikaela M Ceder
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Emilia Lekholm
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Axel Klaesson
- Pharmaceutical Cell Biology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Rekha Tripathi
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Nadine Schweizer
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Lydia Weldai
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Sourabh Patil
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Robert Fredriksson
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| |
Collapse
|
14
|
da Silva DC, Valentão P, Andrade PB, Pereira DM. Endoplasmic reticulum stress signaling in cancer and neurodegenerative disorders: Tools and strategies to understand its complexity. Pharmacol Res 2020; 155:104702. [PMID: 32068119 DOI: 10.1016/j.phrs.2020.104702] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 02/10/2020] [Accepted: 02/13/2020] [Indexed: 12/12/2022]
Abstract
The endoplasmic reticulum (ER) comprises a network of tubules and vesicles that constitutes the largest organelle of the eukaryotic cell. Being the location where most proteins are synthesized and folded, it is crucial for the upkeep of cellular homeostasis. Disturbed ER homeostasis triggers the activation of a conserved molecular machinery, termed the unfolded protein response (UPR), that comprises three major signaling branches, initiated by the protein kinase RNA-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1 (IRE1) and the activating transcription factor 6 (ATF6). Given the impact of this intricate signaling network upon an extensive list of cellular processes, including protein turnover and autophagy, ER stress is involved in the onset and progression of multiple diseases, including cancer and neurodegenerative disorders. There is, for this reason, an increasing number of publications focused on characterizing and/or modulating ER stress, which have resulted in a wide array of techniques employed to study ER-related molecular events. This review aims to sum up the essentials on the current knowledge of the molecular biology of endoplasmic reticulum stress, while highlighting the available tools used in studies of this nature.
Collapse
Affiliation(s)
- Daniela Correia da Silva
- REQUIMTE/LAQV, Laboratório de Farmacognosia, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-213, Porto, Portugal
| | - Patrícia Valentão
- REQUIMTE/LAQV, Laboratório de Farmacognosia, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-213, Porto, Portugal
| | - Paula B Andrade
- REQUIMTE/LAQV, Laboratório de Farmacognosia, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-213, Porto, Portugal
| | - David M Pereira
- REQUIMTE/LAQV, Laboratório de Farmacognosia, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-213, Porto, Portugal.
| |
Collapse
|
15
|
Wek RC. Role of eIF2α Kinases in Translational Control and Adaptation to Cellular Stress. Cold Spring Harb Perspect Biol 2018; 10:a032870. [PMID: 29440070 PMCID: PMC6028073 DOI: 10.1101/cshperspect.a032870] [Citation(s) in RCA: 294] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A central mechanism regulating translation initiation in response to environmental stress involves phosphorylation of the α subunit of eukaryotic initiation factor 2 (eIF2α). Phosphorylation of eIF2α causes inhibition of global translation, which conserves energy and facilitates reprogramming of gene expression and signaling pathways that help to restore protein homeostasis. Coincident with repression of protein synthesis, many gene transcripts involved in the stress response are not affected or are even preferentially translated in response to increased eIF2α phosphorylation by mechanisms involving upstream open reading frames (uORFs). This review highlights the mechanisms regulating eIF2α kinases, the role that uORFs play in translational control, and the impact that alteration of eIF2α phosphorylation by gene mutations or small molecule inhibitors can have on health and disease.
Collapse
Affiliation(s)
- Ronald C Wek
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5126
| |
Collapse
|
16
|
Ceder MM, Lekholm E, Hellsten SV, Perland E, Fredriksson R. The Neuronal and Peripheral Expressed Membrane-Bound UNC93A Respond to Nutrient Availability in Mice. Front Mol Neurosci 2017; 10:351. [PMID: 29163028 PMCID: PMC5671512 DOI: 10.3389/fnmol.2017.00351] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 10/13/2017] [Indexed: 12/31/2022] Open
Abstract
Many transporters such as the solute carriers belonging to the Major facilitator superfamily Pfam clan are orphans in that their tissue and cellular localization as well as substrate profile and function are still unknown. Here we have characterized the putative solute carrier UNC93A. We aimed to investigate the expression profile on both protein and mRNA level of UNC93A in mouse since it has not been clarified. UNC93A staining was found in cortex, hippocampus and cerebellum. It was found to be expressed in many neurons, but not all, with staining located in close proximity to the plasma membrane. Furthermore, we aimed to extend the starvation data available for Unc93a in hypothalamic cell cultures from mouse. We investigated the Unc93a alterations with focus on amino acid deprivation in embryonic cortex cells from mice as well as 24 h starvation in adult male mice and compared it to recently studied putative and known solute carriers. Unc93a expression was found both in the brain and peripheral organs, in low to moderate levels in the adult mice and was affected by amino acid deprivation in embryonic cortex cultures and starvation in in vivo samples. In conclusion, the membrane-bound UNC93A is expressed in both the brain and peripheral tissues and responds to nutrient availability in mice.
Collapse
Affiliation(s)
- Mikaela M Ceder
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Emilia Lekholm
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Sofie V Hellsten
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Emelie Perland
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Robert Fredriksson
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| |
Collapse
|
17
|
A feed-forward regulation of endothelin receptors by c-Jun in human non-pigmented ciliary epithelial cells and retinal ganglion cells. PLoS One 2017; 12:e0185390. [PMID: 28938016 PMCID: PMC5609771 DOI: 10.1371/journal.pone.0185390] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 09/12/2017] [Indexed: 12/21/2022] Open
Abstract
c-Jun, c-Jun N-terminal kinase(JNK) and endothelin B (ETB) receptor have been shown to contribute to the pathogenesis of glaucoma. Previously, we reported that an increase of c-Jun and CCAAT/enhancer binding protein β (C/EBPβ) immunohistostaining is associated with upregulation of the ETB receptor within the ganglion cell layer of rats with elevated intraocular pressure (IOP). In addition, both transcription factors regulate the expression of the ETB receptor in human non-pigmented ciliary epithelial cells (HNPE). The current study addressed the mechanisms by which ET-1 produced upregulation of ET receptors in primary rat retinal ganglion cells (RGCs) and HNPE cells. Treatment of ET-1 and ET-3 increased the immunocytochemical staining of c-Jun and C/EBPβ in primary rat RGCs and co-localization of both transcription factors was observed. A marked increase in DNA binding activity of AP-1 and C/EBPβ as well as elevated protein levels of c-Jun and c-Jun-N-terminal kinase (JNK) were detected following ET-1 treatment in HNPE cells. Overexpression of ETA or ETB receptor promoted the upregulation of c-Jun and also elevated its promoter activity. In addition, upregulation of C/EBPβ augmented DNA binding and mRNA expression of c-Jun, and furthermore, the interaction of c-Jun and C/EBPβ was confirmed using co-immunoprecipitation. Apoptosis of HNPE cells was identified following ET-1 treatment, and overexpression of the ETA or ETB receptor produced enhanced apoptosis. ET-1 mediated upregulation of c-Jun and C/EBPβ and their interaction may represent a novel mechanism contributing to the regulation of endothelin receptor expression. Reciprocally, c-Jun was also found to regulate the ET receptors and C/EBPβ appeared to play a regulatory role in promoting expression of c-Jun. Taken together, the data suggests that ET-1 triggers the upregulation of c-Jun through both ETA and ETB receptors, and conversely c-Jun also upregulates endothelin receptor expression, thereby generating a positive feed-forward loop of endothelin receptor activation and expression. This feed-forward regulation may contribute to RGC death and astrocyte proliferation following ET-1 treatment.
Collapse
|
18
|
Zhou YS, Gu YX, Qi BZ, Zhang YK, Li XL, Fang WH. Porcine circovirus type 2 capsid protein induces unfolded protein response with subsequent activation of apoptosis. J Zhejiang Univ Sci B 2017; 18:316-323. [PMID: 28378569 PMCID: PMC5394096 DOI: 10.1631/jzus.b1600208] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Porcine circovirus type 2 (PCV2) has recently been reported to elicit the unfolded protein response (UPR) via activation of the PERK/eIF2α (RNA-activated protein kinase-like endoplasmic reticulum (ER) kinase/eukaryotic initiation factor 2α) pathway. This study attempted to examine which viral protein might be involved in inducing UPR and whether this cellular event would lead to apoptosis of the cells expressing the viral protein. By transient expression, we found that both replicase (Rep) and capsid (Cap) proteins of PCV2 could induce ER stress as shown by increased phosphorylation of PERK with subsequent activation of the eIF2α-ATF4 (activating transcription factor 4)-CHOP (CCAAT/enhancer-binding protein homologous protein) axis. Cap expression, but not Rep, significantly reduced anti-apoptotic B-cell lymphoma-2 (Bcl-2) and increased caspase-3 cleavage, possibly due to increased expression of CHOP. Since knockdown of PERK by RNA interference clearly reduced Cap-induced CHOP expression, caspase-3 cleavage, and apoptotic cell death possibly by partially rescuing Bcl-2 expression, we propose that there is connection between Cap-induced UPR and apoptosis via the PERK/eIF2α/ATF4/CHOP/Bcl-2 pathway. This study, together with our earlier studies, provides insight into the mechanisms underlying PCV2 pathogenesis.
Collapse
Affiliation(s)
- Ying-Shan Zhou
- College of Animal Science and Technology, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Zhejiang A&F University, Lin'an 311300, China
| | - Yuan-Xing Gu
- Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310058, China
| | - Bao-Zhu Qi
- Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310058, China
| | - Yi-Kai Zhang
- Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310058, China
| | - Xiao-Liang Li
- Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310058, China
| | - Wei-Huan Fang
- College of Animal Science and Technology, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Zhejiang A&F University, Lin'an 311300, China.,Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310058, China
| |
Collapse
|
19
|
Clayton BL, Huang A, Kunjamma RB, Solanki A, Popko B. The Integrated Stress Response in Hypoxia-Induced Diffuse White Matter Injury. J Neurosci 2017; 37:7465-7480. [PMID: 28720571 PMCID: PMC5546113 DOI: 10.1523/jneurosci.2738-16.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 06/02/2017] [Accepted: 06/25/2017] [Indexed: 12/13/2022] Open
Abstract
Currently no treatments exist for preterm infants with diffuse white matter injury (DWMI) caused by hypoxia. Due to the improved care of preterm neonates and increased recognition by advanced imaging techniques, the prevalence of DWMI is increasing. A better understanding of the pathophysiology of DWMI is therefore of critical importance. The integrated stress response (ISR), a conserved eukaryotic response to myriad stressors including hypoxia, may play a role in hypoxia-induced DWMI and may represent a novel target for much needed therapies. In this study, we use in vitro and in vivo hypoxic models of DWMI to investigate whether the ISR is involved in DWMI. We demonstrate that hypoxia activates the ISR in primary mouse oligodendrocyte precursor cells (OPCs) in vitro and that genetically inhibiting the ISR in differentiating OPCs increases their susceptibility to in vitro hypoxia. We also show that a well established in vivo mild chronic hypoxia (MCH) mouse model and a new severe acute hypoxia (SAH) mouse model of DWMI activates the initial step of the ISR. Nonetheless, genetic inhibition of the ISR has no detectable effect on either MCH- or SAH-induced DWMI. In addition, we demonstrate that genetic enhancement of the ISR does not ameliorate MCH- or SAH-induced DWMI. These studies suggest that, while the ISR protects OPCs from hypoxia in vitro, it does not appear to play a major role in either MCH- or SAH-induced DWMI and is therefore not a likely target for therapies aimed at improving neurological outcome in preterm neonates with hypoxia-induced DWMI.SIGNIFICANCE STATEMENT Diffuse white matter injury (DWMI) caused by hypoxia is a leading cause of neurological deficits following premature birth. An increased understanding of the pathogenesis of this disease is critical. The integrated stress response (ISR) is activated by hypoxia and protects oligodendrocyte lineage cells in other disease models. This has led to an interest in the potential role of the ISR in DWMI. Here we examine the ISR in hypoxia-induced DWMI and show that while the ISR protects oligodendrocyte lineage cells from hypoxia in vitro, genetic inhibition or enhancement of the ISR has no effect on hypoxia-induced DWMI in vivo, suggesting that the ISR does not play a major role in and is not a likely therapeutic target for DWMI.
Collapse
Affiliation(s)
- Benjamin L Clayton
- Department of Neurology, The University of Chicago Center for Peripheral Neuropathy, The University of Chicago, Chicago, Illinois 60637, and
| | - Aaron Huang
- Department of Neurology, The University of Chicago Center for Peripheral Neuropathy, The University of Chicago, Chicago, Illinois 60637, and
| | - Rejani B Kunjamma
- Department of Neurology, The University of Chicago Center for Peripheral Neuropathy, The University of Chicago, Chicago, Illinois 60637, and
| | - Ani Solanki
- Animal Resource Center, The University of Chicago, Chicago, Illinois 60637
| | - Brian Popko
- Department of Neurology, The University of Chicago Center for Peripheral Neuropathy, The University of Chicago, Chicago, Illinois 60637, and
| |
Collapse
|
20
|
Collier AE, Wek RC, Spandau DF. Human Keratinocyte Differentiation Requires Translational Control by the eIF2α Kinase GCN2. J Invest Dermatol 2017; 137:1924-1934. [PMID: 28528168 DOI: 10.1016/j.jid.2017.04.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/29/2017] [Accepted: 04/26/2017] [Indexed: 10/19/2022]
Abstract
Appropriate and sequential differentiation of keratinocytes is essential for all functions of the human epidermis. Although transcriptional regulation has proven to be important for keratinocyte differentiation, little is known about the role of translational control. A key mechanism for modulating translation is through phosphorylation of the α subunit of eukaryotic initiation factor 2 (eIF2). A family of different eIF2α kinases function in the integrative stress response to inhibit general protein synthesis coincident with preferential translation of select mRNAs that participate in stress alleviation. Here we demonstrate that translational control through eIF2α phosphorylation is required for normal keratinocyte differentiation. Analyses of polysome profiles revealed that key differentiation genes, including involucrin, are bound to heavy polysomes during differentiation, despite decreased general protein synthesis. Induced eIF2α phosphorylation by the general control nonderepressible 2 (GCN2) protein kinase facilitated translational control and differentiation-specific protein expression during keratinocyte differentiation. Furthermore, loss of GCN2 thwarted translational control, normal epidermal differentiation, and differentiation gene expression in organotypic skin culture. These findings underscore a previously unknown function for GCN2 phosphorylation of eIF2α and translational control in the formation of an intact human epidermis.
Collapse
Affiliation(s)
- Ann E Collier
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Ronald C Wek
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA.
| | - Dan F Spandau
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA; Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana, USA.
| |
Collapse
|
21
|
The NF-κB-dependent and -independent transcriptome and chromatin landscapes of human coronavirus 229E-infected cells. PLoS Pathog 2017; 13:e1006286. [PMID: 28355270 PMCID: PMC5386326 DOI: 10.1371/journal.ppat.1006286] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 04/10/2017] [Accepted: 03/09/2017] [Indexed: 12/20/2022] Open
Abstract
Coronavirus replication takes place in the host cell cytoplasm and triggers inflammatory gene expression by poorly characterized mechanisms. To obtain more insight into the signals and molecular events that coordinate global host responses in the nucleus of coronavirus-infected cells, first, transcriptome dynamics was studied in human coronavirus 229E (HCoV-229E)-infected A549 and HuH7 cells, respectively, revealing a core signature of upregulated genes in these cells. Compared to treatment with the prototypical inflammatory cytokine interleukin(IL)-1, HCoV-229E replication was found to attenuate the inducible activity of the transcription factor (TF) NF-κB and to restrict the nuclear concentration of NF-κB subunits by (i) an unusual mechanism involving partial degradation of IKKβ, NEMO and IκBα and (ii) upregulation of TNFAIP3 (A20), although constitutive IKK activity and basal TNFAIP3 expression levels were shown to be required for efficient virus replication. Second, we characterized actively transcribed genomic regions and enhancers in HCoV-229E-infected cells and systematically correlated the genome-wide gene expression changes with the recruitment of Ser5-phosphorylated RNA polymerase II and prototypical histone modifications (H3K9ac, H3K36ac, H4K5ac, H3K27ac, H3K4me1). The data revealed that, in HCoV-infected (but not IL-1-treated) cells, an extensive set of genes was activated without inducible p65 NF-κB being recruited. Furthermore, both HCoV-229E replication and IL-1 were shown to upregulate a small set of genes encoding immunomodulatory factors that bind p65 at promoters and require IKKβ activity and p65 for expression. Also, HCoV-229E and IL-1 activated a common set of 440 p65-bound enhancers that differed from another 992 HCoV-229E-specific enhancer regions by distinct TF-binding motif combinations. Taken together, the study shows that cytoplasmic RNA viruses fine-tune NF-κB signaling at multiple levels and profoundly reprogram the host cellular chromatin landscape, thereby orchestrating the timely coordinated expression of genes involved in multiple signaling, immunoregulatory and metabolic processes. Coronaviruses are major human and animal pathogens. They belong to a family of plus-strand RNA viruses that have extremely large genomes and encode a variety of proteins involved in virus-host interactions. The four common coronaviruses (HCoV-229E, NL63, OC43, HKU1) cause mainly upper respiratory tract infections, while zoonotic coronaviruses (SARS-CoV and MERS-CoV) cause severe lung disease, including acute respiratory distress syndrome (ARDS). The molecular basis for this fundamentally different pathology is incompletely understood. Our study provides a genome-wide investigation of epigenetic changes occurring in response to HCoV-229E. We identify at high resolution a large number of regulatory regions in the genome of infected cells that coordinate de novo gene transcription. Many of these genes have immunomodulatory functions and, most likely, contribute to limiting viral replication, while other factors may promote viral replication. The study provides an intriguing example of a virus that completes its entire life cycle in the cytoplasm while sending multiple signals to the nuclear chromatin compartment to adjust the host cell repertoire of transcribed genes. The approach taken in this study is expected to provide a suitable framework for future studies aimed at dissecting and comparing host responses to representative coronaviruses with different pathogenic potential in humans.
Collapse
|
22
|
Davuluri G, Krokowski D, Guan BJ, Kumar A, Thapaliya S, Singh D, Hatzoglou M, Dasarathy S. Metabolic adaptation of skeletal muscle to hyperammonemia drives the beneficial effects of l-leucine in cirrhosis. J Hepatol 2016; 65:929-937. [PMID: 27318325 PMCID: PMC5069194 DOI: 10.1016/j.jhep.2016.06.004] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 06/06/2016] [Accepted: 06/07/2016] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Increased skeletal muscle ammonia uptake with loss of muscle mass adversely affects clinical outcomes in cirrhosis. Hyperammonemia causes reduced protein synthesis and sarcopenia but the cellular responses to impaired proteostasis and molecular mechanism of l-leucine induced adaptation to ammonia induced stress were determined. METHODS Response to activation of amino acid deficiency sensor, GCN2, in the skeletal muscle from cirrhotic patients and the portacaval anastomosis (PCA) rat were quantified. During hyperammonemia and l-leucine supplementation, protein synthesis, phosphorylation of eIF2α, mTORC1 signaling, l-leucine transport and response to l-leucine supplementation were quantified. Adaptation to cellular stress via ATF4 and its target GADD34 were also determined. RESULTS Activation of the eIF2α kinase GCN2 and impaired mTORC1 signaling were observed in skeletal muscle from cirrhotic patients and PCA rats. Ammonia activated GCN2 mediated eIF2α phosphorylation (eIF2α-P) and impaired mTORC1 signaling that inhibit protein synthesis in myotubes and MEFs. Adaptation to ammonia induced stress did not involve translational reprogramming by activation transcription factor 4 (ATF4) dependent induction of the eIF2α-P phosphatase subunit GADD34. Instead, ammonia increased expression of the leucine/glutamine exchanger SLC7A5, l-leucine uptake and intracellular l-leucine levels, the latter not being sufficient to rescue the inhibition of protein synthesis, due to potentially enhanced mitochondrial sequestration of l-leucine. l-leucine supplementation rescued protein synthesis inhibition caused by hyperammonemia. CONCLUSIONS Response to hyperammonemia is reminiscent of the cellular response to amino acid starvation, but lacks the adaptive ATF4 dependent integrated stress response (ISR). Instead, hyperammonemia-induced l-leucine uptake was an adaptive response to the GCN2-mediated decreased protein synthesis. LAY SUMMARY Sarcopenia or skeletal muscle loss is the most frequent complication in cirrhosis but there are no treatments because the cause(s) of muscle loss in liver disease are not known. Results from laboratory experiments in animals and muscle cells were validated in human patients with cirrhosis to show that ammonia plays a key role in causing muscle loss in patients with cirrhosis. We identified a novel stress response to ammonia in the muscle that decreases muscle protein content that can be reversed by supplementation with the amino acid l-leucine.
Collapse
Affiliation(s)
- Gangarao Davuluri
- Departments of Pathobiology, Gastroenterology and Hepatology, Cleveland Clinic, Cleveland OH
| | - Dawid Krokowski
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland OH
| | - Bo-Jhih Guan
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland OH
| | - Avinash Kumar
- Departments of Pathobiology, Gastroenterology and Hepatology, Cleveland Clinic, Cleveland OH
| | - Samjhana Thapaliya
- Departments of Pathobiology, Gastroenterology and Hepatology, Cleveland Clinic, Cleveland OH
| | - Dharmvir Singh
- Departments of Pathobiology, Gastroenterology and Hepatology, Cleveland Clinic, Cleveland OH
| | - Maria Hatzoglou
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland OH
| | - Srinivasan Dasarathy
- Departments of Pathobiology, Gastroenterology and Hepatology, Cleveland Clinic, Cleveland OH
| |
Collapse
|
23
|
Garaeva AA, Kovaleva IE, Chumakov PM, Evstafieva AG. Mitochondrial dysfunction induces SESN2 gene expression through Activating Transcription Factor 4. Cell Cycle 2016; 15:64-71. [PMID: 26771712 DOI: 10.1080/15384101.2015.1120929] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
We found that inhibitors of mitochondrial respiratory chain complexes III (myxothiazol) and I (piericidin A) in some epithelial carcinoma cell lines induce transcription of the p53-responsive SESN2 gene that plays an important role in stress response and homeostatic regulation. However, the effect did not depend on p53 because i) there was no induction of p53 after the treatment with piericidin A; ii) after the treatment with myxothiazol the peak of SESN2 gene upregulation occurred as early as 5h, before the onset of p53 activation (13h); iii) a supplementation with uridine that abolishes the p53 activation in response to myxothiazol did not abrogate the induction of SESN2 transcripts; iv) in the p53 negative HCT116 p53 -/- cells SESN2 transcription could be also induced by myxothiazol. In response to the respiratory chain inhibitors we observed an induction of ATF4, the key transcription factor of the integrated stress response (ISR). We found that the induction of SESN2 transcripts could be prevented by the ISR inhibitory small molecule ISRIB. Also, by inhibiting or overexpressing ATF4 with specific shRNA or ATF4-expressing constructs, respectively, we have confirmed the role of ATF4 in the SESN2 gene upregulation induced by mitochondrial dysfunction. At a distance of 228 bp upstream from the SESN2 transcription start site we found a candidate sequence for the ATF4 binding site and confirmed its requirement for the induction of SESN2 in luciferase reporter experiments. We suggest that the upregulation of SESN2 by mitochondrial dysfunction provides a homeostatic feedback that attenuates biosynthetic processes during temporal losses of energy supply from mitochondria thereby assisting better adaptation and viability of cells in hostile environments.
Collapse
Affiliation(s)
- Alisa A Garaeva
- a Department of Bioengineering and Bioinformatics , Lomonosov Moscow State University , Moscow , Russia.,b Engelhardt Institute of Molecular Biology, Russian Academy of Sciences , Moscow , Russia
| | - Irina E Kovaleva
- c Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow , Russia
| | - Peter M Chumakov
- b Engelhardt Institute of Molecular Biology, Russian Academy of Sciences , Moscow , Russia
| | - Alexandra G Evstafieva
- a Department of Bioengineering and Bioinformatics , Lomonosov Moscow State University , Moscow , Russia.,c Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow , Russia
| |
Collapse
|
24
|
SHP-2 phosphatase controls aryl hydrocarbon receptor-mediated ER stress response in mast cells. Arch Toxicol 2016; 91:1739-1748. [PMID: 27709270 DOI: 10.1007/s00204-016-1861-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 09/28/2016] [Indexed: 12/17/2022]
Abstract
Previously we reported that exposure of mouse and human mast cells to aryl hydrocarbon receptor (AhR) ligands resulted in reactive oxygen species (ROS)- and calcium (Ca2+)-dependent activation of mast cells in vitro and in vivo. However, the mechanisms through which the AhR-ligand axis mediates stress response, Ca2+ signaling and subsequent mast cell activation remain to be fully elucidated. Evidence is provided herein that SHP-2 is critical in regulating AhR-mediated ER stress response and intracellular Ca2+ dynamics. We found that an AhR ligand, FICZ, induced significant reduction of intracellular GSH and an increased level of intracellular ROS. Significantly, we showed that in FICZ-treated mast cells, SHP-2 promoted, in a ROS-dependent manner, ER stress response involving primarily the PERK signaling pathway, ATF4 activation and eIF2α phosphorylation, which could be reversed by the addition of an antioxidant, NAC, and was inhibited in cells with SHP-2 knockdown. Our findings suggested that SHP-2 is critical in controlling ER stress signals in response to AhR activation, which provides a new mechanistic insight into how the AhR-ligand axis regulates cellular adaptation to the environmental insult in mast cells.
Collapse
|
25
|
Pakos-Zebrucka K, Koryga I, Mnich K, Ljujic M, Samali A, Gorman AM. The integrated stress response. EMBO Rep 2016; 17:1374-1395. [PMID: 27629041 DOI: 10.15252/embr.201642195] [Citation(s) in RCA: 1486] [Impact Index Per Article: 185.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 08/23/2016] [Indexed: 02/06/2023] Open
Abstract
In response to diverse stress stimuli, eukaryotic cells activate a common adaptive pathway, termed the integrated stress response (ISR), to restore cellular homeostasis. The core event in this pathway is the phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α) by one of four members of the eIF2α kinase family, which leads to a decrease in global protein synthesis and the induction of selected genes, including the transcription factor ATF4, that together promote cellular recovery. The gene expression program activated by the ISR optimizes the cellular response to stress and is dependent on the cellular context, as well as on the nature and intensity of the stress stimuli. Although the ISR is primarily a pro-survival, homeostatic program, exposure to severe stress can drive signaling toward cell death. Here, we review current understanding of the ISR signaling and how it regulates cell fate under diverse types of stress.
Collapse
Affiliation(s)
- Karolina Pakos-Zebrucka
- Apoptosis Research Centre, National University of Ireland Galway, Galway, Ireland School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Izabela Koryga
- Apoptosis Research Centre, National University of Ireland Galway, Galway, Ireland School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Katarzyna Mnich
- Apoptosis Research Centre, National University of Ireland Galway, Galway, Ireland School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Mila Ljujic
- Apoptosis Research Centre, National University of Ireland Galway, Galway, Ireland School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Afshin Samali
- Apoptosis Research Centre, National University of Ireland Galway, Galway, Ireland School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Adrienne M Gorman
- Apoptosis Research Centre, National University of Ireland Galway, Galway, Ireland School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| |
Collapse
|
26
|
Young SK, Wek RC. Upstream Open Reading Frames Differentially Regulate Gene-specific Translation in the Integrated Stress Response. J Biol Chem 2016; 291:16927-35. [PMID: 27358398 DOI: 10.1074/jbc.r116.733899] [Citation(s) in RCA: 243] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Translation regulation largely occurs during initiation, which features ribosome assembly onto mRNAs and selection of the translation start site. Short, upstream ORFs (uORFs) located in the 5'-leader of the mRNA can be selected for translation. Multiple transcripts associated with stress amelioration are preferentially translated through uORF-mediated mechanisms during activation of the integrated stress response (ISR) in which phosphorylation of the α subunit of eIF2 results in a coincident global reduction in translation initiation. This review presents key features of uORFs that serve to optimize translational control that is essential for regulation of cell fate in response to environmental stresses.
Collapse
Affiliation(s)
- Sara K Young
- From the Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5126
| | - Ronald C Wek
- From the Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5126
| |
Collapse
|
27
|
Zeng H, Zhang JM, Du Y, Wang J, Ren Y, Li M, Li H, Cai Z, Chu Q, Yang C. Crosstalk between ATF4 and MTA1/HDAC1 promotes osteosarcoma progression. Oncotarget 2016; 7:7329-42. [PMID: 26797758 PMCID: PMC4872789 DOI: 10.18632/oncotarget.6940] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 01/01/2016] [Indexed: 02/01/2023] Open
Abstract
The stress response gene activating transcription factor 4 (ATF4) is involved in metastatic behavior and cellular protection. Here we show that ATF4 is upregulated in osteosarcoma (OS) cell lines and patient clinical samples as compared to matched non-tumor tissue. Overexpression of ATF4 in OS cells promoted cell proliferation, migration and lung metastasis. Furthermore, the expression of ATF4 was markedly reduced in metastasis associated protein (MTA1) or histone deacetylase 1 (HDAC1) knockdown OS cells, but MTA1 overexpression increased the stability and activity of ATF4 protein via ATF4 deacetylation by HDAC1. ATF4 in turn enhanced the expression of MTA1 and HDAC1 at the transcription level, suggesting a positive feedback loop between ATF4 and MTA1/HDAC1. Clinically, the level of ATF4 was positively correlated with that of MTA1 in OS. Mice injected with ATF4-overexpressing cells exhibited a higher rate of tumor growth, and the average weight of these tumors was ~90% greater than the controls. Taken together, these data establish a direct correlation between ATF4-induced OS progression and MTA1/HDAC1-associated metastasis, and support the potential therapeutic value of targeting ATF4 in the treatment of OS.
Collapse
Affiliation(s)
- Heng Zeng
- Department of Orthopedics, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Jin-ming Zhang
- Department of Orthopedics, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Yu Du
- Department of Orthopedics, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
- Department of Orthopedic Surgery, The Second Affiliated Hospital, Chongqing Medical University, Chongqing 400016, P.R. China
| | - Jiang Wang
- Department of Orthopedics, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Ye Ren
- Department of Orthopedics, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Mi Li
- Department of Orthopedics, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Hao Li
- Department of Orthopedics, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Zhuo Cai
- Department of Orthopedics, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Qian Chu
- Department of Oncology, Tongji Hospital of Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Caihong Yang
- Department of Orthopedics, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| |
Collapse
|
28
|
Translational Repression Protects Human Keratinocytes from UVB-Induced Apoptosis through a Discordant eIF2 Kinase Stress Response. J Invest Dermatol 2015; 135:2502-2511. [PMID: 25950825 PMCID: PMC4567905 DOI: 10.1038/jid.2015.177] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 02/02/2015] [Accepted: 04/23/2015] [Indexed: 01/08/2023]
Abstract
This study delineates the mechanisms by which ultraviolet B (UVB) regulates protein synthesis in human keratinocytes and the importance of translational control in cell survival. Translation initiation is regulated by phosphorylation of eukaryotic initiation factor 2 (eIF2~P), which causes decreased global protein synthesis coincident with enhanced translation of selected stress-related transcripts, such as ATF4. ATF4 is a transcriptional activator of the Integrated Stress Response (ISR), which has cytoprotective functions as well as apoptotic signals through the downstream transcriptional regulator CHOP (GADD153/DDIT3). We determined that UVB irradiation is a potent inducer of eIF2~P in keratinocytes, leading to decreased levels of translation initiation. However, expression of ATF4 or CHOP was not induced by UVB as compared to traditional ISR activators. The rationale for this discordant response is that ATF4 mRNA is reduced by UVB, and despite its ability to be preferentially translated there are diminished levels of available transcript. Forced expression of ATF4 and CHOP protein prior to UVB irradiation significantly enhanced apoptosis, suggesting that this portion of the ISR is deleterious in keratinocytes following UVB. Inhibition of eIF2~P and translational control reduced viability following UVB, which was alleviated by cycloheximide, indicating that translation repression through eIF2~P is central to keratinocyte survival.
Collapse
|
29
|
Wei N, Zhu LQ, Liu D. ATF4: a Novel Potential Therapeutic Target for Alzheimer's Disease. Mol Neurobiol 2014; 52:1765-1770. [PMID: 25381575 DOI: 10.1007/s12035-014-8970-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 10/28/2014] [Indexed: 12/27/2022]
Abstract
Activating transcription factor 4 (ATF4) belongs to the activating transcription factor family and its expression is increased upon the stimulation of a diverse array of microenvironmental stresses. ATF4 plays a major role in the development, metabolism, and memory formation. Alzheimer's disease (AD) is a prevalent neurodegenerative disease in aged population. The dominant pathological changes in AD brain, including the neurofibrillary tangles, consist of hyperphosphorylated tau protein, senile plaques composed of β-amyloid proteins, loss of neurons in the whole brain, and dysfunction of synapses. The protein level of ATF4 is upregulated in both AD brain and AD mouse model, indicating its latent roles in the pathogenesis of this disease. In this paper, we reviewed the related literatures about the interaction of ATF4 with the different types of pathological changes in AD brain and pointed out some unsolved problems in this area. We also proposed that a fine regulation of ATF4 in separate neurons or brain regions might be benefit to the therapy of AD.
Collapse
Affiliation(s)
- Na Wei
- Institute of Brain Research, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China
| | - Ling-Qiang Zhu
- Institute of Brain Research, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China
| | - Dan Liu
- Institute of Brain Research, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China.
- Department of Medical Genetics, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China.
| |
Collapse
|
30
|
Perino A, Pols TWH, Nomura M, Stein S, Pellicciari R, Schoonjans K. TGR5 reduces macrophage migration through mTOR-induced C/EBPβ differential translation. J Clin Invest 2014; 124:5424-36. [PMID: 25365223 DOI: 10.1172/jci76289] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 09/30/2014] [Indexed: 02/06/2023] Open
Abstract
The bile acid-responsive G protein-coupled receptor TGR5 is involved in several metabolic processes, and recent studies suggest that TGR5 activation may promote pathways that are protective against diet-induced diabetes. Here, we investigated the role of macrophage-specific TGR5 signaling in protecting adipose tissue from inflammation and associated insulin resistance. Examination of adipose tissue from obese mice lacking macrophage Tgr5 revealed enhanced inflammation, increased chemokine expression, and higher macrophage numbers compared with control obese animals. Moreover, macrophage-specific deletion of Tgr5 exacerbated insulin resistance in obese animals. Conversely, pharmacological activation of TGR5 markedly decreased LPS-induced chemokine expression in primary macrophages. This reduction was mediated by AKT-dependent activation of mTOR complex 1, which in turn induced the differential translation of the dominant-negative C/EBPβ isoform, liver inhibitory protein (LIP). Overall, these studies reveal a signaling pathway downstream of TGR5 that modulates chemokine expression in response to high-fat diet and suggest that targeting this pathway has the potential to be therapeutically exploited for prevention of chronic inflammatory diseases and type 2 diabetes mellitus.
Collapse
|
31
|
Harada A, Okazaki E, Okada S, Tachibana T, Ohkawa Y. Production of a monoclonal antibody for C/EBPβ: the subnuclear localization of C/EBPβ in mouse L929 cells. Monoclon Antib Immunodiagn Immunother 2014; 33:34-7. [PMID: 24555934 DOI: 10.1089/mab.2013.0069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The CCAAT/enhancer-binding protein (C/EBP)β belongs to the C/EBP family of proteins that possesses a basic leucine zipper DNA-binding domain. These proteins bind DNA by dimerization and play a role in the transcriptional regulation of various cells. There are six different types of C/EBPs, and some form isoforms through the use of alternative translation initiation sites. The functional analysis of the C/EBP family is therefore difficult to achieve. Here we report on the production of specific monoclonal antibodies against mouse C/EBPβ using a rat medial iliac lymph node method. Immunoblotting using C/EBPβ monoclonal antibodies identified two types of isoforms, while immunostaining revealed a subnuclear localization for C/EBPβ. Use of this antibody should contribute to the further elucidation of the transcriptional regulatory function of C/EBPβ.
Collapse
Affiliation(s)
- Akihito Harada
- 1 Department of Advanced Medical Initiatives, JST-CREST, Faculty of Medicine, Kyushu University , Fukuoka, Japan
| | | | | | | | | |
Collapse
|
32
|
ATF4 and IRE1α inhibit DNA repair protein DNA-dependent protein kinase 1 induced by heat shock. Mol Cell Biochem 2012; 371:225-32. [DOI: 10.1007/s11010-012-1439-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2012] [Accepted: 08/25/2012] [Indexed: 02/06/2023]
|