1
|
Pancha I, Chokshi K, Tanaka K, Imamura S. Microalgal Target of Rapamycin (TOR): A Central Regulatory Hub for Growth, Stress Response and Biomass Production. Plant Cell Physiol 2020; 61:675-684. [PMID: 32105317 DOI: 10.1093/pcp/pcaa023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 02/17/2020] [Indexed: 06/10/2023]
Abstract
Target of rapamycin (TOR) is an evolutionarily conserved protein kinase that plays an important role in the regulation of cell growth and the sensing of nutrient and energy status in eukaryotes. In yeasts and mammals, the roles of TOR have been very well described and various functions of TOR signaling in plant lineages have also been revealed over the past 20 years. In the case of microalgae, the functions of TOR have been primarily studied in the model green alga Chlamydomonas reinhardtii and were summarized in an earlier single review article. However, the recent development of tools for the functional analysis of TOR has helped to reveal the involvement of TOR in various functions, including autophagy, transcription, translation, accumulation of energy storage molecules, etc., in microalgae. In the present review, we discuss recent novel findings relating to TOR signaling and its roles in microalgae along with relevant information on land plants and also provide details of topics that must be addressed in future studies to reveal how TOR regulates various physiological functions in microalgae.
Collapse
Affiliation(s)
- Imran Pancha
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503 Japan
- Department of Biology, SRM University-AP, Amaravati, Andhra Pradesh 522502, India
| | - Kaumeel Chokshi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503 Japan
| | - Kan Tanaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503 Japan
| | - Sousuke Imamura
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503 Japan
| |
Collapse
|
2
|
Krüger K, Geist K, Stuhldreier F, Schumacher L, Blümel L, Remke M, Wesselborg S, Stork B, Klöcker N, Bormann S, Roos WP, Honnen S, Fritz G. Multiple DNA damage-dependent and DNA damage-independent stress responses define the outcome of ATR/Chk1 targeting in medulloblastoma cells. Cancer Lett 2018; 430:34-46. [PMID: 29753759 DOI: 10.1016/j.canlet.2018.05.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 05/03/2018] [Accepted: 05/08/2018] [Indexed: 01/04/2023]
Abstract
Targeting of oncogene-driven replicative stress as therapeutic option for high-risk medullobastoma was assessed using a panel of medulloblastoma cells differing in their c-Myc expression [i.e. group SHH (c-Myc low) vs. group 3 (c-Myc high)]. High c-Myc levels were associated with hypersensitivity to pharmacological Chk1 and ATR inhibition but not to CDK inhibition nor to conventional (genotoxic) anticancer therapeutics. The enhanced sensitivity of group 3 medulloblastoma cells to Chk1 inhibitors likely results from enhanced damage to intracellular organelles, elevated replicative stress and DNA damage and activation of apoptosis/necrosis. Furthermore, Chk1 inhibition differentially affected c-Myc expression and functions. In c-Myc high cells, Chk1 blockage decreased c-Myc and p-GSK3α protein and increased p21 and GADD45A mRNA expression. By contrast, c-Myc low cells revealed increased p-GSK3β protein and CHOP and DUSP1 mRNA levels. Inhibition of Chk1 sensitized medulloblastoma cells to additional replication stress evoked by cisplatin independent of c-Myc. Importantly, Chk1 inhibition only caused minor toxicity in primary rat neurons in vitro. Collectively, targeting of ATR/Chk1 effectively triggers death in high-risk medulloblastoma, potentiates the anticancer efficacy of cisplatin and is well tolerated in non-cancerous neuronal cells.
Collapse
Affiliation(s)
- Katharina Krüger
- Institute of Toxicology, Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Katharina Geist
- Institute of Toxicology, Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Fabian Stuhldreier
- Institute of Molecular Medicine I, Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Lena Schumacher
- Institute of Toxicology, Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Lena Blümel
- Clinic of Pediatric Oncology/Neuro-Oncology, Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Marc Remke
- Clinic of Pediatric Oncology/Neuro-Oncology, Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Sebastian Wesselborg
- Institute of Molecular Medicine I, Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Björn Stork
- Institute of Molecular Medicine I, Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Nicolaj Klöcker
- Institute of Neurophysiology, Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Stefanie Bormann
- Institute of Toxicology, Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Wynand P Roos
- Institute of Toxicology, University Medical Center, Obere Zahlbacher Str. 67, 55131, Mainz, Germany
| | - Sebastian Honnen
- Institute of Toxicology, Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Gerhard Fritz
- Institute of Toxicology, Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany.
| |
Collapse
|
3
|
Isono M, Hoffmann MJ, Pinkerneil M, Sato A, Michaelis M, Cinatl J, Niegisch G, Schulz WA. Checkpoint kinase inhibitor AZD7762 strongly sensitises urothelial carcinoma cells to gemcitabine. J Exp Clin Cancer Res 2017; 36:1. [PMID: 28049532 PMCID: PMC5209915 DOI: 10.1186/s13046-016-0473-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 12/12/2016] [Indexed: 01/22/2023]
Abstract
Background More effective chemotherapies are urgently needed for bladder cancer, a major cause of morbidity and mortality worldwide. We therefore explored the efficacy of the combination of gemcitabine and AZD7762, a checkpoint kinase 1/2 (CHK1/2) inhibitor, for bladder cancer. Methods Viability, clonogenicity, cell cycle distribution and apoptosis were assessed in urothelial cancer cell lines and various non-malignant urothelial cells treated with gemcitabine and AZD7762. DNA damage was assessed by γH2A.X and 53-BP1 staining and checkpoint activation was followed by Western blotting. Pharmacological inhibition of CHK1 and CHK2 was compared to downregulation of either CHK1 or CHK2 using siRNAs. Results Combined use of gemcitabine and AZD7762 synergistically reduced urothelial carcinoma cell viability and colony formation relative to either single treatment. Non-malignant urothelial cells were substantially less sensitive to this drug combination. Gemcitabine plus AZD7762 inhibited cell cycle progression causing cell accumulation in S-phase. Moreover, the combination induced pronounced levels of apoptosis as indicated by an increase in the fraction of sub-G1 cells, in the levels of cleaved PARP, and in caspase 3/7 activity. Mechanistic investigations showed that AZD7762 treatment inhibited the repair of gemcitabine-induced double strand breaks by interference with CHK1, since siRNA-mediated depletion of CHK1 but not of CHK2 mimicked the effects of AZD7762. Conclusions AZD7762 enhanced sensitivity of urothelial carcinoma cells to gemcitabine by inhibiting DNA repair and disturbing checkpoints. Combining gemcitabine with CHK1 inhibition holds promise for urothelial cancer therapy. Electronic supplementary material The online version of this article (doi:10.1186/s13046-016-0473-1) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Makoto Isono
- Department of Urology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Michèle J Hoffmann
- Department of Urology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Maria Pinkerneil
- Department of Urology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Akinori Sato
- Department of Urology, National Defense Medical College, Namiki 3-2, 359-8513, Tokorozawa, Japan
| | - Martin Michaelis
- Centre for Molecular Processing and School of Biosciences, University of Kent, Canterbury, CT2 7NJ, UK
| | - Jindrich Cinatl
- Institut für Medizinische Virologie, Klinikum der Goethe-Universität, Paul-Ehrlich‑Str. 40, 60596, Frankfurt am Main, Germany
| | - Günter Niegisch
- Department of Urology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Wolfgang A Schulz
- Department of Urology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany.
| |
Collapse
|
4
|
Fleck O, Vejrup-Hansen R, Watson A, Carr AM, Nielsen O, Holmberg C. Spd1 accumulation causes genome instability independently of ribonucleotide reductase activity but functions to protect the genome when deoxynucleotide pools are elevated. J Cell Sci 2013; 126:4985-94. [PMID: 23986475 DOI: 10.1242/jcs.132837] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cullin4, Ddb1 and Cdt2 are core subunits of the ubiquitin ligase complex CRL4(Cdt2), which controls genome stability by targeting Spd1 for degradation during DNA replication and repair in fission yeast. Spd1 has an inhibitory effect on ribonucleotide reductase (RNR), the activity of which is required for deoxynucleotide (dNTP) synthesis. The failure to degrade Spd1 in mutants where CRL4(Cdt2) is defective leads to DNA integrity checkpoint activation and dependency. This correlates with a lower dNTP pool. Pools are restored in a spd1-deleted background and this also suppresses checkpoint activation and dependency. We hypothesized that fission yeast with RNR hyperactivity would display a mutator phenotype on their own, but also possibly repress aspects of the phenotype associated with the inability to target Spd1 for degradation. Here, we report that a mutation in the R1 subunit of ribonucleotide reductase cdc22 (cdc22-D57N), which alleviated allosteric feedback inhibition, caused a highly elevated dNTP pool that was further increased by deleting spd1. The Δspd1 cdc22-D57N double mutant had elevated mutation rates and was sensitive to damaging agents that cause DNA strand breaks, demonstrating that Spd1 can protect the genome when dNTP pools are high. In ddb1-deleted cells, cdc22-D57N also potently elevated RNR activity, but failed to allow cell growth independently of the intact checkpoint. Our results provide evidence that excess Spd1 interferes with other functions in addition to its inhibitory effect on ribonucleotide reduction to generate replication stress and genome instability.
Collapse
Affiliation(s)
- Oliver Fleck
- Cell Cycle and Genome Stability Group, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N, Denmark
| | | | | | | | | | | |
Collapse
|