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Lin TY, Cheng AC, Chuang HC, Yao JY. Resveratrol Ameliorates Hyperglycemic Cultured Cells and Inhibits the Rheb/mTOR Interaction. Nat Prod Commun 2023. [DOI: 10.1177/1934578x221147376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Resveratrol (RSV) is a natural polyphenol with anti-diabetic effects and has been reported to ameliorate diabetes-induced metabolic disorders through regulating activities of the mTOR signaling pathway. To delineate the effects of RSV treatment on the mTOR signaling pathway, hyperglycemic HepG2 cells were used for the following experiments. Cellular glucose uptake assays showed that high-glucose levels in the culture medium decelerate the glucose uptake of cultured cells. Co-immunoprecipitation showed that high-glucose culture promotes the interaction between mTOR and Rheb-GTP, which is the active form of Rheb. RSV treatment of the cells suppressed this interaction and accelerated the glucose uptake. Western blotting revealed that RSV down-regulated members of the mTOR signaling pathway, namely SREBP1, p70, and S6. Additionally, RSV ameliorated the metabolic disorders, including the decreased levels of AMPK, glycogen synthase, and glucose-6-phosphatase, in hyperglycemic HepG2 cells. These results indicate that RSV inhibits the Rheb/mTOR interaction and ameliorates metabolic disorders associated with high-glucose levels.
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Affiliation(s)
- Tzu-Yung Lin
- Key Laboratory of Functional and Clinical Translational Medicine, Fujian Province University, Xiamen Medical College, Xiamen, Fujian, China
- Department and Graduate Institute of Aquaculture, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
| | - Ann-Chang Cheng
- Department and Graduate Institute of Aquaculture, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
| | - Hsiang-Chieh Chuang
- Department and Graduate Institute of Aquaculture, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
| | - Jeng-Yuan Yao
- Key Laboratory of Functional and Clinical Translational Medicine, Fujian Province University, Xiamen Medical College, Xiamen, Fujian, China
- Department of Preventive Medicine, Public Health School, Fujian Medical University, Fuzhou, Fujian, China
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de la Monte SM. Malignant Brain Aging: The Formidable Link Between Dysregulated Signaling Through Mechanistic Target of Rapamycin Pathways and Alzheimer's Disease (Type 3 Diabetes). J Alzheimers Dis 2023; 95:1301-1337. [PMID: 37718817 PMCID: PMC10896181 DOI: 10.3233/jad-230555] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
Malignant brain aging corresponds to accelerated age-related declines in brain functions eventually derailing the self-sustaining forces that govern independent vitality. Malignant brain aging establishes the path toward dementing neurodegeneration, including Alzheimer's disease (AD). The full spectrum of AD includes progressive dysfunction of neurons, oligodendrocytes, astrocytes, microglia, and the microvascular systems, and is mechanistically driven by insulin and insulin-like growth factor (IGF) deficiencies and resistances with accompanying deficits in energy balance, increased cellular stress, inflammation, and impaired perfusion, mimicking the core features of diabetes mellitus. The underlying pathophysiological derangements result in mitochondrial dysfunction, abnormal protein aggregation, increased oxidative and endoplasmic reticulum stress, aberrant autophagy, and abnormal post-translational modification of proteins, all of which are signature features of both AD and dysregulated insulin/IGF-1-mechanistic target of rapamycin (mTOR) signaling. This article connects the dots from benign to malignant aging to neurodegeneration by reviewing the salient pathologies associated with initially adaptive and later dysfunctional mTOR signaling in the brain. Effective therapeutic and preventive measures must be two-pronged and designed to 1) address complex and shifting impairments in mTOR signaling through the re-purpose of effective anti-diabetes therapeutics that target the brain, and 2) minimize the impact of extrinsic mediators of benign to malignant aging transitions, e.g., inflammatory states, obesity, systemic insulin resistance diseases, and repeated bouts of general anesthesia, by minimizing exposures or implementing neuroprotective measures.
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Affiliation(s)
- Suzanne M. de la Monte
- Departments of Pathology and Laboratory Medicine, Medicine, Neurology and Neurosurgery, Rhode Island Hospital, Lifespan Academic Institutions, and the Warren Alpert Medical School of Brown University, Providence, RI, USA
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Huang J, Chen L, Wu J, Ai D, Zhang JQ, Chen TG, Wang L. Targeting the PI3K/AKT/mTOR Signaling Pathway in the Treatment of Human Diseases: Current Status, Trends, and Solutions. J Med Chem 2022; 65:16033-16061. [PMID: 36503229 DOI: 10.1021/acs.jmedchem.2c01070] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway is one of the most important intracellular pathways involved in cell proliferation, growth, differentiation, and survival. Therefore, this route is a prospective biological target for treating various human diseases, such as tumors, neurodegenerative diseases, pulmonary fibrosis, and diabetes. An increasing number of clinical studies emphasize the necessity of developing novel molecules targeting the PI3K/AKT/mTOR pathway. This review focuses on recent advances in ATP-competitive inhibitors, allosteric inhibitors, covalent inhibitors, and proteolysis-targeting chimeras against the PI3K/AKT/mTOR pathway, and highlights possible solutions for overcoming the toxicities and acquired drug resistance of currently available drugs. We also provide recommendations for the future design and development of promising drugs targeting this pathway.
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Affiliation(s)
- Jindi Huang
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, Joint International Research Laboratory of Synthetic Biology and Medicine, Guangdong Provincial Engineering and Technology Research Center of Biopharmaceuticals, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Liye Chen
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, Joint International Research Laboratory of Synthetic Biology and Medicine, Guangdong Provincial Engineering and Technology Research Center of Biopharmaceuticals, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Jiangxia Wu
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, Joint International Research Laboratory of Synthetic Biology and Medicine, Guangdong Provincial Engineering and Technology Research Center of Biopharmaceuticals, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Daiqiao Ai
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, Joint International Research Laboratory of Synthetic Biology and Medicine, Guangdong Provincial Engineering and Technology Research Center of Biopharmaceuticals, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Ji-Quan Zhang
- College of Pharmacy, Guizhou Medical University, Guiyang 550004, China
| | - Tie-Gen Chen
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Room 109, Building C, SSIP Healthcare and Medicine Demonstration Zone, Zhongshan Tsuihang New District, Zhongshan, Guangdong 528400, China
| | - Ling Wang
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, Joint International Research Laboratory of Synthetic Biology and Medicine, Guangdong Provincial Engineering and Technology Research Center of Biopharmaceuticals, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
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4
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Amar-Schwartz A, Ben Hur V, Jbara A, Cohen Y, Barnabas GD, Arbib E, Siegfried Z, Mashahreh B, Hassouna F, Shilo A, Abu-Odeh M, Berger M, Wiener R, Aqeilan R, Geiger T, Karni R. S6K1 phosphorylates Cdk1 and MSH6 to regulate DNA repair. eLife 2022; 11:79128. [PMID: 36189922 PMCID: PMC9529248 DOI: 10.7554/elife.79128] [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: 04/08/2022] [Accepted: 08/26/2022] [Indexed: 11/22/2022] Open
Abstract
The mTORC1 substrate, S6 Kinase 1 (S6K1), is involved in the regulation of cell growth, ribosome biogenesis, glucose homeostasis, and adipogenesis. Accumulating evidence has suggested a role for mTORC1 signaling in the DNA damage response. This is mostly based on the findings that mTORC1 inhibitors sensitized cells to DNA damage. However, a direct role of the mTORC1-S6K1 signaling pathway in DNA repair and the mechanism by which this signaling pathway regulates DNA repair is unknown. In this study, we discovered a novel role for S6K1 in regulating DNA repair through the coordinated regulation of the cell cycle, homologous recombination (HR) DNA repair (HRR) and mismatch DNA repair (MMR) mechanisms. Here, we show that S6K1 orchestrates DNA repair by phosphorylation of Cdk1 at serine 39, causing G2/M cell cycle arrest enabling homologous recombination and by phosphorylation of MSH6 at serine 309, enhancing MMR. Moreover, breast cancer cells harboring RPS6KB1 gene amplification show increased resistance to several DNA damaging agents and S6K1 expression is associated with poor survival of breast cancer patients treated with chemotherapy. Our findings reveal an unexpected function of S6K1 in the DNA repair pathway, serving as a tumorigenic barrier by safeguarding genomic stability. Damage to the DNA in our cells can cause harmful changes that, if unchecked, can lead to the development of cancer. To help prevent this, cellular mechanisms are in place to repair defects in the DNA. A particular process, known as the mTORC1-S6K1 pathway is suspected to be important for repair because when this pathway is blocked, cells become more sensitive to DNA damage. It is still unknown how the various proteins involved in the mTORC1-S6K1 pathway contribute to repairing DNA. One of these proteins, S6K1, is an enzyme involved in coordinating cell growth and survival. The tumor cells in some forms of breast cancer produce more of this protein than normal, suggesting that S6K1 benefits these cells’ survival. However, it is unclear exactly how the enzyme does this. Amar-Schwartz, Ben-Hur, Jbara et al. studied the role of S6K1 using genetically manipulated mouse cells and human cancer cells. These experiments showed that the protein interacts with two other proteins involved in DNA repair and activates them, regulating two different repair mechanisms and protecting cells against damage. These results might explain why some breast cancer tumors are resistant to radiotherapy and chemotherapy treatments, which aim to kill tumor cells by damaging their DNA. If this is the case, these findings could help clinicians choose more effective treatment options for people with cancers that produce additional S6K1. In the future, drugs that block the activity of the enzyme could make cancer cells more susceptible to chemotherapy.
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Affiliation(s)
- Adi Amar-Schwartz
- Department of Biochemistry and Molecular Biology, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Vered Ben Hur
- Department of Biochemistry and Molecular Biology, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Amina Jbara
- Department of Biochemistry and Molecular Biology, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Yuval Cohen
- Department of Biochemistry and Molecular Biology, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Georgina D Barnabas
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Eliran Arbib
- Lautenberg Center for Immunology and Cancer Research, Department of Immunology and Cancer Research, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Zahava Siegfried
- Department of Biochemistry and Molecular Biology, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Bayan Mashahreh
- Department of Biochemistry and Molecular Biology, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Fouad Hassouna
- Department of Biochemistry and Molecular Biology, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Asaf Shilo
- Department of Biochemistry and Molecular Biology, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Mohammad Abu-Odeh
- Lautenberg Center for Immunology and Cancer Research, Department of Immunology and Cancer Research, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Michael Berger
- Lautenberg Center for Immunology and Cancer Research, Department of Immunology and Cancer Research, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Reuven Wiener
- Department of Biochemistry and Molecular Biology, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Rami Aqeilan
- Lautenberg Center for Immunology and Cancer Research, Department of Immunology and Cancer Research, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Tamar Geiger
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Rotem Karni
- Department of Biochemistry and Molecular Biology, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
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Fazil WFWM, Amanah A, Abduraman MA, Sulaiman SF, Wahab HA, Tan ML. The Effects of Deoxyelephantopin on the Akt/mTOR/P70S6K Signaling Pathway in MCF-7 Breast Carcinoma Cells In Vitro. J Pharmacol Pharmacother 2022. [DOI: 10.1177/0976500x221114003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Objective To determine the effects of deoxyelephantopin on mTOR and its related target molecules (Akt/mTOR/P70S6K) in the ER-positive breast cancer cell line. Materials and Methods Primary in silico simulations were determined, and the effects of deoxyelephantopin on the phosphorylation of the Akt/mTOR/P70S6K molecules were evaluated using AlphaScreen-based assays and western blot analysis, respectively. Results Based on the estimated FEB and K i values, deoxyelephantopin appeared to have a stronger affinity toward P70S6K as compared with Akt and mTOR. Both deoxyelephantopin and control inhibitors were observed to form hydrogen bonds with the same key residue, Leu175 of the P70S6K molecule. Deoxyelephantopin downregulated the p-P70S6K protein expression significantly from 18 µM ( P < .05) and onward. Based on the AlphaScreen assay, deoxyelephantopin produced a concentration-dependent inhibition on the phosphorylation of P70S6K with an IC50 value of 7.13 µM. Conclusion Deoxyelephantopin induced cell death in MCF-7 cells, possibly via DNA fragmentation, inhibition of the phosphorylation of P70SK6, and downregulation of the relative p-p70S6K protein expression levels.
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Affiliation(s)
- Wan Failiza Wan Mohamad Fazil
- Malaysian Institute of Pharmaceuticals and Nutraceuticals (IPharm), National Institutes of Biotechnology Malaysia (NIBM), Pulau Pinang, Malaysia
| | - Azimah Amanah
- Malaysian Institute of Pharmaceuticals and Nutraceuticals (IPharm), National Institutes of Biotechnology Malaysia (NIBM), Pulau Pinang, Malaysia
| | - Muhammad Asyraf Abduraman
- Advanced Medical and Dental Institute, Universiti Sains Malaysia, SAINS@BERTAM, Kepala Batas, Pulau Pinang, Malaysia
| | - Shaida Fariza Sulaiman
- Discipline of Clinical Pharmacy, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Pulau Pinang, Malaysia
| | - Habibah Abdul Wahab
- Discipline of Clinical Pharmacy, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Pulau Pinang, Malaysia
| | - Mei Lan Tan
- Malaysian Institute of Pharmaceuticals and Nutraceuticals (IPharm), National Institutes of Biotechnology Malaysia (NIBM), Pulau Pinang, Malaysia
- Advanced Medical and Dental Institute, Universiti Sains Malaysia, SAINS@BERTAM, Kepala Batas, Pulau Pinang, Malaysia
- Discipline of Clinical Pharmacy, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Pulau Pinang, Malaysia
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Jiang H, Zhang N, Ge H, Wei J, Xu X, Meng X, Qian K, Zheng Y, Wang J. S6K1 acts through FOXO to regulate juvenile hormone biosynthesis in the red flour beetle, Tribolium castaneum. JOURNAL OF INSECT PHYSIOLOGY 2022; 140:104405. [PMID: 35679992 DOI: 10.1016/j.jinsphys.2022.104405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 06/01/2022] [Accepted: 06/03/2022] [Indexed: 06/15/2023]
Abstract
As the downstream effector of the target of rapamycin complex 1 (TORC1) signaling pathway, the ribosomal protein S6 kinase (S6K) is an important regulator of insect reproduction, however, the underlying mechanism remains obscure. In this study, a S6K gene, named TcS6K1, was isolated from the red flour beetle, Tribolium castaneum. Analysis of temporal and spatial expression patterns revealed that TcS6K1 is expressed at the highest level in the one-day-old first instar larvae and head of 7-day-old females, respectively. RNAi-mediated knockdown of TcS6K1 in either female or male adults decreased the number of eggs laid, with a concomitant reduction of mRNA levelsof vitellogenin genes, TcVg1 and TcVg2, two male accessory gland secretory proteins, as well as the juvenile hormone (JH) biosynthesis-related gene, farnesol dehydrogenase (TcFDH). While the mRNA and protein levels of the transcription factor forkhead box O (TcFOXO) were not affected, suppression of TcS6K1 expression promoted TcFOXO nuclear translocation to exert its transcriptional action. Further RNAi and EMSA analysis revealed that TcFOXO negatively regulated the expression of TcFDH. These results indicate that S6K might regulate beetles' reproduction through FOXO/JH signaling pathway.
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Affiliation(s)
- Heng Jiang
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Nan Zhang
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Huichen Ge
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Jiaping Wei
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Xin Xu
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Xiangkun Meng
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Kun Qian
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Yang Zheng
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
| | - Jianjun Wang
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou 225009, China.
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Yi SA, Jeon YJ, Lee MG, Nam KH, Ann S, Lee J, Han JW. S6K1 controls adiponectin expression by inducing a transcriptional switch: BMAL1-to-EZH2. Exp Mol Med 2022; 54:324-333. [PMID: 35338256 PMCID: PMC8979988 DOI: 10.1038/s12276-022-00747-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 12/03/2021] [Accepted: 12/29/2021] [Indexed: 11/24/2022] Open
Abstract
Adiponectin (encoded by Adipoq), a fat-derived hormone, alleviates risk factors associated with metabolic disorders. Although many transcription factors are known to control adiponectin expression, the mechanism underlying its fluctuation with regard to metabolic status remains unclear. Here, we show that ribosomal protein S6 kinase 1 (S6K1) controls adiponectin expression by inducing a transcriptional switch between two transcriptional machineries, BMAL1 and EZH2. Active S6K1 induced a suppressive histone code cascade, H2BS36p-EZH2-H3K27me3, leading to suppression of adiponectin expression. Moreover, active S6K1 phosphorylated BMAL1, an important transcription factor regulating the circadian clock system, at serine 42, which led to its dissociation from the Adipoq promoter region. This response resulted in EZH2 recruitment and subsequent H3K27me3 modification of the Adipoq promoter. Upon fasting, inactivation of S6K1 induced the opposite transcriptional switch, EZH2-to-BMAL1, promoting adiponectin expression. Consistently, S6K1-depleted mice exhibited lower H3K27me3 levels and elevated adiponectin expression. These findings identify a novel epigenetic switch system by which S6K1 controls the production of adiponectin, which displays beneficial effects on metabolism.
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Affiliation(s)
- Sang Ah Yi
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
| | - Ye Ji Jeon
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Min Gyu Lee
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Ki Hong Nam
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Sora Ann
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Jaecheol Lee
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
- Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University, Suwon, 16419, Korea.
- Imnewrun Biosciences, Inc, Suwon, 16419, Korea.
| | - Jeung-Whan Han
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
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p70 S6 kinase as a therapeutic target in cancers: More than just an mTOR effector. Cancer Lett 2022; 535:215593. [PMID: 35176419 DOI: 10.1016/j.canlet.2022.215593] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/25/2022] [Accepted: 02/06/2022] [Indexed: 11/23/2022]
Abstract
p70 S6 kinase (p70S6K) is best-known for its regulatory roles in protein synthesis and cell growth by phosphorylating its primary substrate, ribosomal protein S6, upon mitogen stimulation. The enhanced expression/activation of p70S6K has been correlated with poor prognosis in some cancer types, suggesting that it may serve as a biomarker for disease monitoring. p70S6K is a critical downstream effector of the oncogenic PI3K/Akt/mTOR pathway and its activation is tightly regulated by an ordered cascade of Ser/Thr phosphorylation events. Nonetheless, it should be noted that other upstream mechanisms regulating p70S6K at both the post-translational and post-transcriptional levels also exist. Activated p70S6K could promote various aspects of cancer progression such as epithelial-mesenchymal transition, cancer stemness and drug resistance. Importantly, novel evidence showing that p70S6K may also regulate different cellular components in the tumor microenvironment will be discussed. Therapeutic targeting of p70S6K alone or in combination with traditional chemotherapies or other microenvironmental-based drugs such as immunotherapy may represent promising approaches against cancers with aberrant p70S6K signaling. Currently, the only clinically available p70S6K inhibitors are rapamycin analogs (rapalogs) which target mTOR. However, there are emerging p70S6K-selective drugs which are going through active preclinical or clinical trial phases. Moreover, various screening strategies have been used for the discovery of novel p70S6K inhibitors, hence bringing new insights for p70S6K-targeted therapy.
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9
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Nuclear S6K1 regulates cAMP-responsive element-dependent gene transcription through activation of mTOR signal pathway. Biochem Biophys Res Commun 2022; 594:101-108. [DOI: 10.1016/j.bbrc.2022.01.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Accepted: 01/07/2022] [Indexed: 02/03/2023]
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10
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Pottie L, Van Gool W, Vanhooydonck M, Hanisch FG, Goeminne G, Rajkovic A, Coucke P, Sips P, Callewaert B. Loss of zebrafish atp6v1e1b, encoding a subunit of vacuolar ATPase, recapitulates human ARCL type 2C syndrome and identifies multiple pathobiological signatures. PLoS Genet 2021; 17:e1009603. [PMID: 34143769 PMCID: PMC8244898 DOI: 10.1371/journal.pgen.1009603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 06/30/2021] [Accepted: 05/17/2021] [Indexed: 11/27/2022] Open
Abstract
The inability to maintain a strictly regulated endo(lyso)somal acidic pH through the proton-pumping action of the vacuolar-ATPases (v-ATPases) has been associated with various human diseases including heritable connective tissue disorders. Autosomal recessive (AR) cutis laxa (CL) type 2C syndrome is associated with genetic defects in the ATP6V1E1 gene and is characterized by skin wrinkles or loose redundant skin folds with pleiotropic systemic manifestations. The underlying pathological mechanisms leading to the clinical presentations remain largely unknown. Here, we show that loss of atp6v1e1b in zebrafish leads to early mortality, associated with craniofacial dysmorphisms, vascular anomalies, cardiac dysfunction, N-glycosylation defects, hypotonia, and epidermal structural defects. These features are reminiscent of the phenotypic manifestations in ARCL type 2C patients. Our data demonstrates that loss of atp6v1e1b alters endo(lyso)somal protein levels, and interferes with non-canonical v-ATPase pathways in vivo. In order to gain further insights into the processes affected by loss of atp6v1e1b, we performed an untargeted analysis of the transcriptome, metabolome, and lipidome in early atp6v1e1b-deficient larvae. We report multiple affected pathways including but not limited to oxidative phosphorylation, sphingolipid, fatty acid, and energy metabolism together with profound defects on mitochondrial respiration. Taken together, our results identify complex pathobiological effects due to loss of atp6v1e1b in vivo. Cutis laxa syndromes are pleiotropic disorders of the connective tissue, characterized by skin redundancy and variable systemic manifestations. Cutis laxa syndromes are caused by pathogenic variants in genes encoding structural and regulatory components of the extracellular matrix or in genes encoding components of cellular trafficking, metabolism, and mitochondrial function. Pathogenic variants in genes coding for vacuolar-ATPases, a multisubunit complex responsible for the acidification of multiple intracellular vesicles, cause type 2 cutis laxa syndromes, a group of cutis laxa subtypes further characterized by neurological, skeletal, and rarely cardiopulmonary manifestations. To investigate the pathomechanisms of vacuolar-ATPase dysfunction, we generated zebrafish models that lack a crucial subunit of the vacuolar-ATPases. The mutant zebrafish models show morphological and functional features reminiscent of the phenotypic manifestations in cutis laxa patients carrying pathogenic variants in ATP6V1E1. In-depth analysis at multiple -omic levels identified biological signatures that indicate impairment of signaling pathways, lipid metabolism, and mitochondrial respiration. We anticipate that these data will contribute to a better understanding of the pathogenesis of cutis laxa syndromes and other disorders involving defective v-ATPase function, which may eventually improve patient treatment and management.
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Affiliation(s)
- Lore Pottie
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Wouter Van Gool
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Michiel Vanhooydonck
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Franz-Georg Hanisch
- Institute of Biochemistry II, Medical Faculty, University of Cologne, Cologne, Germany
| | - Geert Goeminne
- VIB Metabolomics Core Ghent, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
| | - Andreja Rajkovic
- Department of Food technology, Safety and Health, Faculty of Bioscience Engineering, University of Ghent, Ghent, Belgium
| | - Paul Coucke
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Patrick Sips
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Bert Callewaert
- Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- * E-mail:
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11
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Hać A, Pierzynowska K, Herman-Antosiewicz A. S6K1 Is Indispensible for Stress-Induced Microtubule Acetylation and Autophagic Flux. Cells 2021; 10:929. [PMID: 33920542 PMCID: PMC8073773 DOI: 10.3390/cells10040929] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/09/2021] [Accepted: 04/13/2021] [Indexed: 12/19/2022] Open
Abstract
Autophagy is a specific macromolecule and organelle degradation process. The target macromolecule or organelle is first enclosed in an autophagosome, and then delivered along acetylated microtubules to the lysosome. Autophagy is triggered by stress and largely contributes to cell survival. We have previously shown that S6K1 kinase is essential for autophagic flux under stress conditions. Here, we aimed to elucidate the underlying mechanism of S6K1 involvement in autophagy. We stimulated autophagy in S6K1/2 double-knockout mouse embryonic fibroblasts by exposing them to different stress conditions. Transient gene overexpression or silencing, immunoblotting, immunofluorescence, flow cytometry, and ratiometric fluorescence analyses revealed that the perturbation of autophagic flux in S6K1-deficient cells did not stem from impaired lysosomal function. Instead, the absence of S6K1 abolished stress-induced tubulin acetylation and disrupted the acetylated microtubule network, in turn impairing the autophagosome-lysosome fusion. S6K1 overexpression restored tubulin acetylation and autophagic flux in stressed S6K1/2-deficient cells. Similar effect of S6K1 status was observed in prostate cancer cells. Furthermore, overexpression of an acetylation-mimicking, but not acetylation-resistant, tubulin variant effectively restored autophagic flux in stressed S6K1/2-deficient cells. Collectively, S6K1 controls tubulin acetylation, hence contributing to the autophagic flux induced by different stress conditions and in different cells.
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Affiliation(s)
- Aleksandra Hać
- Department of Medical Biology and Genetics, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland
| | - Karolina Pierzynowska
- Department of Molecular Biology, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland
| | - Anna Herman-Antosiewicz
- Department of Medical Biology and Genetics, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland
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12
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Li Y, Yi L, Cheng S, Wang Y, Wang J, Sun J, Zhang Q, Xu X. Inhibition of canine distemper virus replication by blocking pyrimidine nucleotide synthesis with A77 1726, the active metabolite of the anti-inflammatory drug leflunomide. J Gen Virol 2021; 102. [PMID: 33416466 DOI: 10.1099/jgv.0.001534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Canine distemper virus (CDV) is the aetiological agent that causes canine distemper (CD). Currently, no antiviral drugs have been approved for CD treatment. A77 1726 is the active metabolite of the anti-rheumatoid arthritis (RA) drug leflunomide. It inhibits the activity of Janus kinases (JAKs) and dihydroorotate dehydrogenase (DHO-DHase), a rate-limiting enzyme in de novo pyrimidine nucleotide synthesis. A77 1726 also inhibits the activity of p70 S6 kinase (S6K1), a serine/threonine kinase that phosphorylates and activates carbamoyl-phosphate synthetase (CAD), a second rate-limiting enzyme in the de novo pathway of pyrimidine nucleotide synthesis. Our present study focuses on the ability of A77 1726 to inhibit CDV replication and its underlying mechanisms. Here we report that A77 1726 decreased the levels of the N and M proteins of CDV and lowered the virus titres in the conditioned media of CDV-infected Vero cells. CDV replication was not inhibited by Ruxolitinib (Rux), a JAK-specific inhibitor, but by brequinar sodium (BQR), a DHO-DHase-specific inhibitor, and PF-4708671, an S6K1-specific inhibitor. Addition of exogenous uridine, which restores intracellular pyrimidine nucleotide levels, blocked the antiviral activity of A77 1726, BQR and PF-4708671. A77 1726 and PF-4708671 inhibited the activity of S6K1 in CDV-infected Vero cells, as evidenced by the decreased levels of CAD and S6 phosphorylation. S6K1 knockdown suppressed CDV replication and enhanced the antiviral activity of A77 1726. These observations collectively suggest that the antiviral activity of A77 1726 against CDV is mediated by targeting pyrimidine nucleotide synthesis via inhibiting DHO-DHase activity and S6K1-mediated CAD activation.
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Affiliation(s)
- Yao Li
- College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou 225009, Jiangsu Province, PR China
| | - Li Yi
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Economic Animals and Plant Science, Chinese Academy of Agricultural Sciences, Changchun, PR China
| | - Sipeng Cheng
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Economic Animals and Plant Science, Chinese Academy of Agricultural Sciences, Changchun, PR China
| | - Yongshan Wang
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Key Laboratory of Veterinary Biological Engineering and Technology, Ministry of Agriculture, National Center for Engineering Research of Veterinary Bio-products, Nanjing 210014, PR China
| | - Jiongjiong Wang
- College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou 225009, Jiangsu Province, PR China
| | - Jing Sun
- College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou 225009, Jiangsu Province, PR China
| | - Quan Zhang
- Institutes of Agricultural Science and Technology Development, Yangzhou University Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, PR China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225009, Jiangsu Province, PR China.,College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou 225009, Jiangsu Province, PR China
| | - Xiulong Xu
- College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou 225009, Jiangsu Province, PR China.,Institutes of Agricultural Science and Technology Development, Yangzhou University Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, PR China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225009, Jiangsu Province, PR China
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13
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Laribee RN, Weisman R. Nuclear Functions of TOR: Impact on Transcription and the Epigenome. Genes (Basel) 2020; 11:E641. [PMID: 32532005 PMCID: PMC7349558 DOI: 10.3390/genes11060641] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/04/2020] [Accepted: 06/09/2020] [Indexed: 12/15/2022] Open
Abstract
The target of rapamycin (TOR) protein kinase is at the core of growth factor- and nutrient-dependent signaling pathways that are well-known for their regulation of metabolism, growth, and proliferation. However, TOR is also involved in the regulation of gene expression, genomic and epigenomic stability. TOR affects nuclear functions indirectly through its activity in the cytoplasm, but also directly through active nuclear TOR pools. The mechanisms by which TOR regulates its nuclear functions are less well-understood compared with its cytoplasmic activities. TOR is an important pharmacological target for several diseases, including cancer, metabolic and neurological disorders. Thus, studies of the nuclear functions of TOR are important for our understanding of basic biological processes, as well as for clinical implications.
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Affiliation(s)
- R. Nicholas Laribee
- Department of Pathology and Laboratory Medicine, College of Medicine and Center for Cancer Research, University of Tennessee Health Science Center, 19 South Manassas, Cancer Research Building Rm 318, Memphis, TN 38163, USA
| | - Ronit Weisman
- Department of Natural and Life Sciences, The Open University of Israel, University Road 1, Ra’anana 4353701, Israel
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14
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Dumbuya JS, Chen L, Shu SY, Ma L, Luo W, Li F, Wu JY, Wang B. G-CSF attenuates neuroinflammation and neuronal apoptosis via the mTOR/p70SK6 signaling pathway in neonatal Hypoxia-Ischemia rat model. Brain Res 2020; 1739:146817. [PMID: 32246916 DOI: 10.1016/j.brainres.2020.146817] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 03/19/2020] [Accepted: 03/31/2020] [Indexed: 11/16/2022]
Abstract
BACKGROUND Hypoxic-ischemic encephalopathy (HIE) is an important cause of permanent damage to the central nervous system, associated with long-lasting neurological disabilities and neurodevelopmental impairment in neonates. Granulocyte-colony stimulating factor (G-CSF) has been shown to have neuroprotective activity in a variety of experimental brain injury models and G-CSF is a standard treatment in chemotherapeutic-induced neutropenia. The underlying mechanisms are still unclear. The mTOR (mammalian target of rapamycin) signaling pathway is a master regulator of cell growth and proliferation in the nervous system. However, the effects of G-CSF treatment on the mTOR signaling pathway have not been elucidated in neonates with hypoxic-ischemic (HI) brain injury. Our study investigated the neuroprotective effect of G-CSF on neonates with hypoxic-ischemic (HI) brain injury and the possible mechanism involving the mTOR/p70S6K pathway. METHODS Sprague-Dawley rat pups at postnatal day 7 (P7) were subjected to right unilateral carotid artery ligation followed by hypoxic (8% oxygen and balanced nitrogen) exposure for 2.5 h or sham surgery. Pups received normal saline, G-CSF, G-CSF combined with rapamycin or ethanol (vehicle for rapamycin) intraperitoneally. On postnatal day 9 (P9), TTC staining for infarct volume, and Nissl and TUNEL staining for neuronal cell injury were conducted. Activation of mTOR/p70S6K pathway, cleaved caspase-3 (CC3), Bax and Bcl-2 and cytokine expression levels were determined by western blotting. RESULTS The G-CSF treated group was associated with significantly reduced infarction volume and decreased TUNEL positive neuronal cells compared to the HI group treated with saline. The expression levels of TNF-α and IL-1ß were significantly decreased in the G-CSF treated group, while IL-10 expression level was increased. The relative immunoreactivity of p-mTOR and p-p70S6K was significantly reduced in the HI group compared to sham. The HI group treated with G-CSF showed significant upregulated protein expression for p-mTOR and p-p70S6K levels compared to the HI group treated with saline. Furthermore, G-CSF treatment increased Bcl-2 expression levels and decreased CC3 and Bax expression levels in the ipsilateral hemispheres of the HI brain. The effects induced by G-CSF were all reversed by rapamycin. CONCLUSION Treatment with G-CSF decreases inflammatory mediators and apoptotic factors, attenuating neuroinflammation and neuronal apoptosis via the mTOR/p70S6K signalling pathway, which represents a potential target for treating HI induced brain damage in neonatal HIE.
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Affiliation(s)
- John Sieh Dumbuya
- Department of Pediatrics, Zhujiang Hospital of Southern Medical University, Guangzhou 510282 PR China
| | - Lu Chen
- Department of Pediatrics, Zhujiang Hospital of Southern Medical University, Guangzhou 510282 PR China
| | - Si Yun Shu
- Department of Pediatrics, Zhujiang Hospital of Southern Medical University, Guangzhou 510282 PR China
| | - Lin Ma
- Department of Radiotherapy, Chinese PLA General Hospital, Beijing 100853 PR China
| | - Wei Luo
- Department of Pediatrics, Zhujiang Hospital of Southern Medical University, Guangzhou 510282 PR China
| | - Fei Li
- Department of Pediatrics, Zhujiang Hospital of Southern Medical University, Guangzhou 510282 PR China
| | - Jang-Yen Wu
- Department of Biochemical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, United States.
| | - Bin Wang
- Department of Pediatrics, Zhujiang Hospital of Southern Medical University, Guangzhou 510282 PR China.
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15
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Wang JY, Fan H. Assessing the efficacy of mammalian target of rapamycin inhibitors by phosphorylation of p70S6K in CD4-positive cells of liver transplant patients. Medicine (Baltimore) 2019; 98:e17457. [PMID: 31651849 PMCID: PMC6824824 DOI: 10.1097/md.0000000000017457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The activity of p70S6 kinase located downstream of the mammalian target of rapamycin (mTOR) pathway is sensitive to mTOR inhibitors. However, the methods of assessing p70S6 kinase activity are still unclear. This study aimed to investigate p70S6 kinase activity in CD4-positive cells of liver transplant patients.Liver transplant patients treated with mTOR inhibitors were recruited from Beijing Chaoyang Hospital between October 2014 and October 2016. The influence of mycophenolic acid (MPA) derivatives and prednisone on p70S6 kinase phosphorylation in CD4-positive cells was examined in liver transplant patients and healthy controls (HCs). The phosphorylation of p70S6K in CD4 + CD25 regulatory T cells (Treg cells) and CD4 + CD25- T effector cells was analyzed by phospho-flow cytometry.The phospho-flow technique detected a significant loss of p70S6 kinase phosphorylation in CD4-positive cells of patients treated with mTOR inhibitors compared with HCs. MPA derivatives and prednisone did not affect p70S6 kinase phosphorylation significantly. No significant difference in p70S6 kinase phosphorylation was observed when the whole blood was stored within 3 hours at room temperature. The phosphorylation of p70S6K was significantly lower in CD4 + CD25 Treg cells than in CD4 + CD25-T effector cells in HCs. After liver transplant patients were treated with mTOR inhibitors, p70S6K phosphorylation was more reduced in CD4 + CD25-T effector cells than in CD4 + CD25 Treg cells.The presence of phosphorylation of p70S6 kinase in CD4-positive cells was reduced in liver transplant patients who were treated by mTOR inhibitors.
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Affiliation(s)
- Jun-Yu Wang
- Doctor of Clinical Medicine, Emergency Department of Beijing Chaoyang Hospital of the Capital Medical University,
| | - Hua Fan
- Hepatobiliary Surgery Department of Beijing Chaoyang Hospital of the Capital Medical University, Beijing, China
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16
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Ahmed AR, Owens RJ, Stubbs CD, Parker AW, Hitchman R, Yadav RB, Dumoux M, Hawes C, Botchway SW. Direct imaging of the recruitment and phosphorylation of S6K1 in the mTORC1 pathway in living cells. Sci Rep 2019; 9:3408. [PMID: 30833605 PMCID: PMC6399282 DOI: 10.1038/s41598-019-39410-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 01/23/2019] [Indexed: 01/11/2023] Open
Abstract
Knowledge of protein signalling pathways in the working cell is seen as a primary route to identifying and developing targeted medicines. In recent years there has been a growing awareness of the importance of the mTOR pathway, making it an attractive target for therapeutic intervention in several diseases. Within this pathway we have focused on S6 kinase 1 (S6K1), the downstream phosphorylation substrate of mTORC1, and specifically identify its juxtaposition with mTORC1. When S6K1 is co-expressed with raptor we show that S6K1 is translocated from the nucleus to the cytoplasm. By developing a novel biosensor we demonstrate in real-time, that phosphorylation and de-phosphorylation of S6K1 occurs mainly in the cytoplasm of living cells. Furthermore, we show that the scaffold protein raptor, that typically recruits mTOR substrates, is not always involved in S6K1 phosphorylation. Overall, we demonstrate how FRET-FLIM imaging technology can be used to show localisation of S6K1 phosphorylation in living cells and hence a key site of action of inhibitors targeting mTOR phosphorylation.
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Affiliation(s)
- Abdullah R Ahmed
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0FA, UK
| | - Raymond J Owens
- Protein Production UK, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0FA, UK.,The Wellcome Centre for Human Genetics, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Christopher D Stubbs
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0FA, UK
| | - Anthony W Parker
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0FA, UK
| | - Richard Hitchman
- Evotec (UK) Ltd, 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire, OX14 4RZ, UK
| | - Rahul B Yadav
- Evotec (UK) Ltd, 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire, OX14 4RZ, UK
| | - Maud Dumoux
- Protein Production UK, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0FA, UK.,Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK
| | - Chris Hawes
- Oxford Brookes University, Headington Campus, Oxford, OX3 0BP, UK
| | - Stanley W Botchway
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0FA, UK.
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17
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Nam KH, Yi SA, Lee J, Lee MG, Park JH, Oh H, Lee J, Park JW, Han JW. Eudesmin impairs adipogenic differentiation via inhibition of S6K1 signaling pathway. Biochem Biophys Res Commun 2018; 505:1148-1153. [PMID: 30316515 DOI: 10.1016/j.bbrc.2018.09.188] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 09/29/2018] [Indexed: 12/25/2022]
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18
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Chen J, Sun J, Prinz RA, Li Y, Xu X. Gingerenone A Sensitizes the Insulin Receptor and Increases Glucose Uptake by Inhibiting the Activity of p70 S6 Kinase. Mol Nutr Food Res 2018; 62:e1800709. [PMID: 30296358 DOI: 10.1002/mnfr.201800709] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 09/04/2018] [Indexed: 12/26/2022]
Abstract
SCOPE The bioactive constituents in ginger extract are responsible for anti-hyperglycemic effects and the underlying mechanisms are incompletely understood. Gingerenone A (Gin A) has been identified as an inhibitor of p70 S6 (S6K1), a kinase that plays a critical role in the pathogenesis of insulin resistance. This study aims to evaluate if Gin A can sensitize the insulin receptor by inhibiting S6K1 activity. METHODS AND RESULTS Western blot analysis reveals that Gin A induces phosphatidylinositide-3 kinase (PI3K) feedback activation in murine 3T3-L1 adipocytes and rat L6 myotubes, as evidenced by increased AKTS473 and S6K1T389 but decreases S6S235/236 and insulin receptor substrate 1 (IRS-1)S1101 phosphorylation. Western blot and immunoprecipitation analysis reveal that Gin A increases insulin receptor tyrosine phosphorylation in L6 myotubes and IRS-1 binding to the PI3K in 3T3-L1 adipocytes. Confocal microscopy reveals that Gin A enhances insulin-induced translocation of glucose transporter 4 (GLUT4) into the cell membrane in L6 cells. 2-NBDG (2-N-(Nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose) Fluorescent assay reveals that Gin A enhances insulin-stimulated glucose uptake in 3T3-L1 adipocytes and L6 myotubes. CONCLUSIONS Gin A overcomes insulin resistance and increases glucose uptake by inhibiting S6K1 activity. Gin A or other plant-derived S6K1 inhibitors could be developed as novel antidiabetic agents.
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Affiliation(s)
- Junhong Chen
- Institute of Comparative Medicine, Yangzhou, 225009, Jiangsu Province, China.,College of Veterinary Medicine, Yangzhou, 225009, Jiangsu Province, China
| | - Jing Sun
- Institute of Comparative Medicine, Yangzhou, 225009, Jiangsu Province, China.,College of Veterinary Medicine, Yangzhou, 225009, Jiangsu Province, China
| | - Richard A Prinz
- Department of Surgery, NorthShore University Health System, Evanston, IL, USA
| | - Yi Li
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Xiulong Xu
- Institute of Comparative Medicine, Yangzhou, 225009, Jiangsu Province, China.,College of Veterinary Medicine, Yangzhou, 225009, Jiangsu Province, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu Province, China.,Department of Cell and Molecular Medicine, Rush University Medical Center, Chicago, IL, 60612, USA
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19
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Yi SA, Lee J, Park SK, Kim JY, Park JW, Lee MG, Nam KH, Park JH, Oh H, Kim S, Han J, Kim BK, Jo DG, Han JW. Fermented ginseng extract, BST204, disturbs adipogenesis of mesenchymal stem cells through inhibition of S6 kinase 1 signaling. J Ginseng Res 2018; 44:58-66. [PMID: 32148390 PMCID: PMC7033330 DOI: 10.1016/j.jgr.2018.08.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/26/2018] [Accepted: 08/03/2018] [Indexed: 12/12/2022] Open
Abstract
Background The biological and pharmacological effects of BST204, a fermented ginseng extract, have been reported in various disease conditions. However, its molecular action in metabolic disease remains poorly understood. In this study, we identified the antiadipogenic activity of BST204 resulting from its inhibition of the S6 kinase 1 (S6K1) signaling pathway. Methods The inhibitory effects of BST204 on S6K1 signaling were investigated by immunoblot, nuclear fractionation, immunoprecipitation analyses. The antiadipogenic effect of BST204 was evaluated by measuring mRNA levels of adipogenic genes and by chromatin immunoprecipitation and quantitative real-time polymerase chain reaction analysis. Results Treatment with BST204 inhibited activation and nuclear translocation of S6K1, further decreasing the interaction between S6K1 and histone H2B in 10T1/2 mesenchymal stem cells. Subsequently, phosphorylation of H2B at serine 36 (H2BS36p) by S6K1 was reduced by BST204, inducing an increase in the mRNA expression of Wnt6, Wnt10a, and Wnt10b, which disturbed adipogenic differentiation and promoted myogenic and early osteogenic gene expression. Consistently, BST204 treatment during adipogenic commitment suppressed the expression of adipogenic marker genes and lipid drop formation. Conclusion Our results indicate that BST204 blocks adipogenesis of mesenchymal stem cells through the inhibition of S6K1-mediated histone phosphorylation. This study suggests the potential therapeutic strategy using BST204 to combat obesity and musculoskeletal diseases.
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Affiliation(s)
- Sang Ah Yi
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Jieun Lee
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Sun Kyu Park
- Research Institute, Green Cross WellBeing, Seongnam, Republic of Korea
| | - Jeom Yong Kim
- Research Institute, Green Cross WellBeing, Seongnam, Republic of Korea
| | - Jong Woo Park
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Min Gyu Lee
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Ki Hong Nam
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Jee Hun Park
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Hwamok Oh
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Saetbyul Kim
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Jihoon Han
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Bo Kyung Kim
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Dong-Gyu Jo
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Jeung-Whan Han
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
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20
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Shaw LC, Li Calzi S, Li N, Moldovan L, Sengupta-Caballero N, Quigley JL, Ivan M, Jun B, Bazan NG, Boulton ME, Busik J, Neu J, Grant MB. Enteral Arg-Gln Dipeptide Administration Increases Retinal Docosahexaenoic Acid and Neuroprotectin D1 in a Murine Model of Retinopathy of Prematurity. Invest Ophthalmol Vis Sci 2018; 59:858-869. [PMID: 29490339 PMCID: PMC5815421 DOI: 10.1167/iovs.17-23034] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Low levels of the long chain polyunsaturated fatty acid (LCPUFA) docosahexaenoic acid (DHA) have been implicated in retinopathy of prematurity (ROP). However, oral DHA suffers from poor palatability and is associated with increased bleeding in premature infants. We asked whether oral administration of the neutraceutical arginine-glutamine (Arg-Glu) could increase retinal DHA and improve outcomes in a mouse model of oxygen-induced retinopathy (OIR). Methods Postnatal day 7 (P7) pups were maintained at 75% oxygen for 5 days and then returned to room air on P12. Pups were gavaged twice daily with Arg-Gln or vehicle from P12 to P17 and eyes were harvested for analysis on P17. Vaso-obliteration and vascular density were assessed on retinal flat mounts and preretinal neovascularization was assessed on retinal cross sections. Retinas were used for measurement of DHA and 10,17S-docosatriene (neuroprotectin D1, NPD1), a key DHA-derived lipid, and for analysis by reverse-phase protein array (RPPA). Results With Arg-Gln treatment, retinal DHA and NPD1 levels were increased in OIR pups. Arg-Gln reduced preretinal neovascularization by 39 ± 6% (P < 0.05) relative to vehicle control. This was accompanied by a restoration of vascular density of the retina in the pups treated with Arg-Gln (73.0 ± 3.0%) compared to vehicle (53.1 ± 3.4%; P < 0.05). Arg-Gln dipeptide restored OIR-induced signaling changes toward normoxia and was associated with normalization of insulin-like growth factor receptor 1 signaling and reduction of apoptosis and an increase in anti-apoptosis proteins. Conclusions Arg-Gln may serve as a safer and easily tolerated nutraceutical agent for prevention or treatment of ROP.
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Affiliation(s)
- Lynn Calvin Shaw
- Department of Ophthalmology, Indiana University, Indianapolis, Indiana, United States
| | - Sergio Li Calzi
- Department of Ophthalmology, University of Alabama, Birmingham, Alabama, United States
| | - Nan Li
- Department of Pediatrics, University of Florida, Gainesville, Florida, United States
| | - Leni Moldovan
- Department of Ophthalmology, Indiana University, Indianapolis, Indiana, United States
| | | | | | - Mircea Ivan
- Department of Medicine, Indiana University, Indianapolis, Indiana, United States
| | - Bokkyoo Jun
- Department of Ophthalmology, Louisiana State University Eye Center, New Orleans, Louisiana, United States
| | - Nicolas G Bazan
- Department of Ophthalmology, Louisiana State University Eye Center, New Orleans, Louisiana, United States
| | - Michael Edwin Boulton
- Department of Ophthalmology, University of Alabama, Birmingham, Alabama, United States
| | - Julia Busik
- Department of Physiology, Michigan State University, East Lansing, Michigan, United States
| | - Josef Neu
- Department of Pediatrics, University of Florida, Gainesville, Florida, United States
| | - Maria B Grant
- Department of Ophthalmology, University of Alabama, Birmingham, Alabama, United States
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21
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Sun J, Mu Y, Jiang Y, Song R, Yi J, Zhou J, Sun J, Jiao X, Prinz RA, Li Y, Xu X. Inhibition of p70 S6 kinase activity by A77 1726 induces autophagy and enhances the degradation of superoxide dismutase 1 (SOD1) protein aggregates. Cell Death Dis 2018; 9:407. [PMID: 29540819 PMCID: PMC5851998 DOI: 10.1038/s41419-018-0441-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 02/21/2018] [Accepted: 02/22/2018] [Indexed: 12/12/2022]
Abstract
Autophagy plays a central role in degrading misfolded proteins such as mutated superoxide dismutase 1 (SOD1), which forms aggregates in motor neurons and is involved in the pathogenesis of amyotrophic lateral sclerosis (ALS). Autophagy is activated when UNC-51-like kinase 1 (ULK1) is phosphorylated at S555 and activated by AMP-activated protein kinase (AMPK). Autophagy is suppressed when ULK1 is phosphorylated at S757 by the mechanistic target of rapamycin (mTOR). Whether p70 S6 kinase 1 (S6K1), a serine/threonine kinase downstream of mTOR, can also regulate autophagy remains uncertain. Here we report that inhibition of S6K1 by A77 1726, the active metabolite of an anti-inflammatory drug leflunomide, induced mTOR feedback activation and ULK1S757 phosphorylation in NSC34 cells, a hybrid mouse motoneuron cell line. Unexpectedly, A77 1726 did not suppress but rather induced autophagy by increasing AMPKT172 and ULK1S555 phosphorylation. Similar observations were made with PF-4708671, a specific S6K1 inhibitor, or with S6K1 siRNA. Further studies showed that A77 1726 induced AMPK phosphorylation by activating the TGF-β-activated kinase 1 (TAK1). Functional studies revealed that A77 1726 induced co-localization of mutant SOD1G93A protein aggregates with autophagosomes and accelerated SOD1G93A protein degradation, which was blocked by inhibition of autophagy through autophagy-related protein 7 (ATG7) siRNA. Our study suggests that S6K1 inhibition induces autophagy through TAK1-mediated AMPK activation in NSC34 cells, and that blocking S6K1 activity by a small molecule inhibitor such as leflunomide may offer a new strategy for ALS treatment.
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Affiliation(s)
- Jing Sun
- Institute of Comparative Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu Province, China
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu Province, China
| | - Yarong Mu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu Province, China
| | - Yuanyuan Jiang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu Province, China
| | - Ruilong Song
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu Province, China
| | - Jianxin Yi
- Department of Physiology, Kansas City University of Medicine and Biosciences, Kansas City, MO, 64106, USA
| | - Jingsong Zhou
- Department of Physiology, Kansas City University of Medicine and Biosciences, Kansas City, MO, 64106, USA
| | - Jun Sun
- Department of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Xinan Jiao
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu Province, China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu Province, China
| | - Richard A Prinz
- Department of Surgery, NorthShore University Health System, Evanston, IL, 60201, USA
| | - Yi Li
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Xiulong Xu
- Institute of Comparative Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu Province, China.
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu Province, China.
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu Province, China.
- Department of Cell and Molecular Medicine Rush University Medical Center, Chicago, IL, 60612, USA.
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Xu X, Sun J, Song R, Doscas ME, Williamson AJ, Zhou J, Sun J, Jiao X, Liu X, Li Y. Inhibition of p70 S6 kinase (S6K1) activity by A77 1726, the active metabolite of leflunomide, induces autophagy through TAK1-mediated AMPK and JNK activation. Oncotarget 2018; 8:30438-30454. [PMID: 28389629 PMCID: PMC5444754 DOI: 10.18632/oncotarget.16737] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 02/03/2017] [Indexed: 12/21/2022] Open
Abstract
mTOR activation suppresses autophagy by phosphorylating ULK1 at S757 and suppressing its enzymatic activity. Here we report that feedback activation of mTOR in the PI-3 kinase pathway by two p70 S6 kinase (S6K1) inhibitors (PF-4708671 and A77 1726, the active metabolite of an immunosuppressive drug leflunomide) or by S6K1 knockdown did not suppress but rather induced autophagy. Suppression of S6K1 activity led to the phosphorylation and activation of AMPK, which then phosphorylated ULK1 at S555. While mTOR feedback activation led to increased phosphorylation of ULK1 at S757, this modification did not the disrupt ULK1-AMPK interaction nor dampen ULK1 S555 phosphorylation and the induction of autophagy. In addition, inhibition of S6K1 activity led to JNK activation, which also contributed to autophagy. 5Z-7-oxozeaenol, a specific inhibitor of TAK1, or TAK1 siRNA blocked A77 1726-induced activation of AMPK and JNK, and LC3 lipidation. Taken together, our study establishes S6K1 as a key player in the PI-3 kinase pathway to suppress autophagy through inhibiting AMPK and JNK in a TAK1-dependent manner.
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Affiliation(s)
- Xiulong Xu
- Institute of Comparative Medicine, Yangzhou University, Yangzhou 225009, Jiangsu Province, P. R. China.,College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu Province, P. R. China.,Department of Anatomy and Cell Biology Rush University Medical Center, Chicago, IL 60612, USA.,Jiangsu Key Laboratory of Zoonosis, Yangzhou University Yangzhou 225009, Jiangsu Province, China
| | - Jing Sun
- Institute of Comparative Medicine, Yangzhou University, Yangzhou 225009, Jiangsu Province, P. R. China.,College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu Province, P. R. China
| | - Ruilong Song
- Core Facility, Yangzhou University, Yangzhou 225009, Jiangsu Province, P. R. China
| | - Michelle E Doscas
- Department of Anatomy and Cell Biology Rush University Medical Center, Chicago, IL 60612, USA
| | | | - Jingsong Zhou
- Department of Physiology, Kansas City University of Medicine and Biosciences, Kansas City, MO 64106, USA
| | - Jun Sun
- Department of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Xinan Jiao
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University Yangzhou 225009, Jiangsu Province, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225009, Jiangsu Province, China
| | - Xiufan Liu
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225009, Jiangsu Province, China.,Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China
| | - Yi Li
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA
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23
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Conditional cell reprogramming involves non-canonical β-catenin activation and mTOR-mediated inactivation of Akt. PLoS One 2017; 12:e0180897. [PMID: 28700668 PMCID: PMC5507294 DOI: 10.1371/journal.pone.0180897] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 06/22/2017] [Indexed: 11/19/2022] Open
Abstract
The combination of irradiated fibroblast feeder cells and Rho kinase inhibitor, Y-267362, converts primary epithelial cells growing in vitro into an undifferentiated adult stem cell-like state that is characterized by long-term proliferation. This cell culture method also maintains the proliferation of adult epithelial stem cells from various tissues. Both primary and adult stem cells retain their tissue-specific differentiation potential upon removal of the culture conditions. Due to the ability to modulate the proliferation and differentiation of the cells, this method is referred to as conditional reprogramming and it is increasingly being used in studies of tumor heterogeneity, personalized medicine and regenerative medicine. However, little is known about the biology of these conditionally reprogrammed (CR) cells. Previously we showed that β-catenin activation, a hallmark of stem cells in vivo, occurs in CR human ectocervical cells (HECs). Here we show that β-catenin-dependent transcription is necessary for the induction of epithelial stem cell markers, and that β-catenin is activated via a non-canonical pathway that is independent of Wnt and Akt/GSK-3. Active Akt actually decreases due to increased mTOR signaling, with a consequent increase in dephosphorylated, active GSK-3. Despite the increase in active GSK-3, β-catenin associates with protein phosphatase 2A (PP2A) and is activated. Inhibition of PP2A catalytic activity reduces both the level of active β-catenin and the acute induction of stem cell markers, suggesting an important role for PP2A in the activation of β-catenin. Moreover, we demonstrate similar results using human prostate and breast cells, indicating that these changes are not restricted to ectocervical epithelial cells and may represent a more fundamental property of conditional reprogramming.
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Khalil A, Parker M, Mpanga R, Cevik SE, Thorburn C, Suvorov A. Developmental Exposure to 2,2',4,4'-Tetrabromodiphenyl Ether Induces Long-Lasting Changes in Liver Metabolism in Male Mice. J Endocr Soc 2017; 1:323-344. [PMID: 29264491 PMCID: PMC5686773 DOI: 10.1210/js.2016-1011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 03/09/2017] [Indexed: 12/11/2022] Open
Abstract
Polybrominated diphenyl ethers (PBDEs) were used as flame-retardant additives in a wide range of polymers. The generations born when environmental concentrations of PBDEs reached their maximum account in the United States for one-fifth of the total population. We hypothesized that exposure to PBDEs during sensitive developmental windows might result in long-lasting changes in liver metabolism. The present study was based on experiments with CD-1 mice and human hepatocellular carcinoma cells (human hepatoma cell line, HepG2). Pregnant mice were exposed to 0.2 mg/kg 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) from gestation day 8 until postnatal day 21. The metabolic health-related outcomes were analyzed on postnatal day 21 and postnatal week 20 in male offspring. Several groups of metabolic genes, including ribosomal and mitochondrial genes, were significantly upregulated in the liver at both points. Genes regulated via mechanistic target of rapamycin (mTOR) pathway, the gatekeeper of metabolic homeostasis, were whether up- or downregulated at both measurement points. On postnatal day 21, but not week 20, both mTOR complexes in the liver were activated, as measured by phosphorylation of their targets. mTOR complexes were also activated by BDE-47 in HepG2 cells in vitro. The following changes were observed at week 20: a decreased number of polyploid hepatocytes, suppressed cytoplasmic S6K1, twofold greater blood insulin-like growth factor-1 and triglycerides, and 2.5-fold lower expression of fatty acid uptake membrane receptor CD36 in liver tissue. Thus, perinatal exposure to environmentally relevant doses of BDE-47 in laboratory mice results in long-lasting changes in liver physiology. Our evidence suggests involvement of the mTOR pathway in the observed metabolic programming of the liver.
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Affiliation(s)
- Ahmed Khalil
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts Amherst, Amherst, Massachusetts 01003
- Medical Biotechnology Department, Genetic Engineering and Biotechnology Research Institute, City of Scientific Research and Technological Applications, Alexandria 21934, Egypt
| | - Mikhail Parker
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts Amherst, Amherst, Massachusetts 01003
| | - Richard Mpanga
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts Amherst, Amherst, Massachusetts 01003
| | - Sebnem E. Cevik
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts Amherst, Amherst, Massachusetts 01003
| | - Cassandra Thorburn
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts Amherst, Amherst, Massachusetts 01003
| | - Alexander Suvorov
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts Amherst, Amherst, Massachusetts 01003
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Xiao LY, Kan WM. p53 modulates the effect of ribosomal protein S6 kinase1 (S6K1) on cisplatin toxicity in chronic myeloid leukemia cells. Pharmacol Res 2017; 119:443-462. [PMID: 28315428 DOI: 10.1016/j.phrs.2017.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 02/08/2017] [Accepted: 03/05/2017] [Indexed: 12/15/2022]
Abstract
Chronic myeloid leukemia (CML) is characterized by the expression of the oncoprotein, BCR-ABL. BCR-ABL inhibitors revolutionized CML chemotherapy while blast crisis (BC) CML patients are less responsive. Since suppression of ribosomal protein S6 kinase1 (S6K1) phosphorylation reverses the resistance to BCR-ABL inhibitor in CML cells and S6K1 inhibitors augment cisplatin toxicity in lung cancer cells, we speculated that combination of S6K1 inhibitor and cisplatin may be beneficial for eliminating BC CML cells. To our surprise, S6K1 inhibition decreased cisplatin-induced DNA damage and cell death only in p53-/- BC CML cells but not in p53+/+ BC CML cells. During the progression of CML, p53 expression either decreases or mutates. Moreover, the expression of p53 affects drug response of CML cells. Our results confirmed that S6K1 inhibition reversed cisplatin toxicity is dependent on p53 expression in CML cells. Moreover, p53 attenuated the phosphorylation and localization of S6K1 via attenuating 3-phosphoinositide dependent protein kinase-1 (PDK1) phosphorylation. Furthermore, S6K1 acts via DNA-PKcs to regulate H2AX phosphorylation and PARP cleavage, respectively. Taken together, our results suggest that p53/PDK1/S6K1 is a novel pathway regulating cisplatin toxicity in BC CML cells.
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Affiliation(s)
- Ling-Yi Xiao
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, 70101 Tainan, Taiwan
| | - Wai-Ming Kan
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, 70101 Tainan, Taiwan; Department of Pharmacology, College of Medicine, National Cheng Kung University, 70101 Tainan, Taiwan.
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26
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Yi SA, Um SH, Lee J, Yoo JH, Bang SY, Park EK, Lee MG, Nam KH, Jeon YJ, Park JW, You JS, Lee SJ, Bae GU, Rhie JW, Kozma SC, Thomas G, Han JW. S6K1 Phosphorylation of H2B Mediates EZH2 Trimethylation of H3: A Determinant of Early Adipogenesis. Mol Cell 2016; 62:443-452. [PMID: 27151441 DOI: 10.1016/j.molcel.2016.03.011] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 01/12/2016] [Accepted: 03/07/2016] [Indexed: 01/23/2023]
Abstract
S6K1 has been implicated in a number of key metabolic responses, which contribute to obesity. Critical among these is the control of a transcriptional program required for the commitment of mesenchymal stem cells to the adipocytic lineage. However, in contrast to its role in the cytosol, the functions and targets of nuclear S6K1 are unknown. Here, we show that adipogenic stimuli trigger nuclear translocation of S6K1, leading to H2BS36 phosphorylation and recruitment of EZH2 to H3, which mediates H3K27 trimethylation. This blocks Wnt gene expression, inducing the upregulation of PPARγ and Cebpa and driving increased adipogenesis. Consistent with this finding, white adipose tissue from S6K1-deficient mice exhibits no detectable H2BS36 phosphorylation or H3K27 trimethylation, whereas both responses are highly elevated in obese humans or in mice fed a high-fat diet. These findings define an S6K1-dependent mechanism in early adipogenesis, contributing to the promotion of obesity.
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Affiliation(s)
- Sang Ah Yi
- Research Center for Epigenome Regulation, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Sung Hee Um
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea; Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Samsung Medical Center, Seoul 06351, Republic of Korea
| | - Jaecheol Lee
- Division of Cardiology, Department of Medicine, Stanford University School of Medicine, 265 Campus Drive, Room G1120B, Stanford, CA 94305-5454, USA
| | - Ji Hee Yoo
- Research Center for Epigenome Regulation, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - So Young Bang
- Research Center for Epigenome Regulation, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Eun Kyung Park
- Research Center for Epigenome Regulation, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Min Gyu Lee
- Research Center for Epigenome Regulation, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Ki Hong Nam
- Research Center for Epigenome Regulation, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Ye Ji Jeon
- Research Center for Epigenome Regulation, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Jong Woo Park
- Research Center for Epigenome Regulation, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Jueng Soo You
- Department of Biochemistry, School of Medicine, Konkuk University, Seoul 05029, Republic of Korea
| | - Sang-Jin Lee
- Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women's University, Seoul 04310, Republic of Korea
| | - Gyu-Un Bae
- Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women's University, Seoul 04310, Republic of Korea
| | - Jong Won Rhie
- Department of Plastic Surgery, College of Medicine, Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Sara C Kozma
- Division of Hematology and Oncology, Department of Internal Medicine, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA; Laboratory of Cancer Metabolism, Catalan Institute of Oncology (ICO), Bellvitge Biomedical Research Institute, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), 08908 Hospitalet de Llobregat, Barcelona, Spain
| | - George Thomas
- Division of Hematology and Oncology, Department of Internal Medicine, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA; Laboratory of Cancer Metabolism, Catalan Institute of Oncology (ICO), Bellvitge Biomedical Research Institute, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), 08908 Hospitalet de Llobregat, Barcelona, Spain; Unitat de Bioquímica, Dep. Ciències Fisiològiques II, Facultat de Medicina, Campus Universitari de Bellvitge - IDIBELL, Universitat de Barcelona, 08908 L'Hospitalet de Llobregat, Catalunya, Barcelona, Spain.
| | - Jeung-Whan Han
- Research Center for Epigenome Regulation, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea.
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Shum M, Bellmann K, St-Pierre P, Marette A. Pharmacological inhibition of S6K1 increases glucose metabolism and Akt signalling in vitro and in diet-induced obese mice. Diabetologia 2016; 59:592-603. [PMID: 26733005 DOI: 10.1007/s00125-015-3839-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 11/13/2015] [Indexed: 01/08/2023]
Abstract
AIMS/HYPOTHESIS The mammalian target of rapamycin complex 1 (mTORC1)/p70 ribosomal S6 kinase (S6K)1 pathway is overactivated in obesity, leading to inhibition of phosphoinositide 3-kinase (PI3K)/Akt signalling and insulin resistance. However, chronic mTORC1 inhibition by rapamycin impairs glucose homeostasis because of robust induction of liver gluconeogenesis. Here, we compared the effect of rapamycin with that of the selective S6K1 inhibitor, PF-4708671, on glucose metabolism in vitro and in vivo. METHODS We used L6 myocytes and FAO hepatocytes to explore the effect of PF-4708671 on the regulation of glucose uptake, glucose production and insulin signalling. We also treated high-fat (HF)-fed obese mice for 7 days with PF-4708671 in comparison with rapamycin to assess glucose tolerance, insulin resistance and insulin signalling in vivo. RESULTS Chronic rapamycin treatment induced insulin resistance and impaired glucose metabolism in hepatic and muscle cells. Conversely, chronic S6K1 inhibition with PF-4708671 reduced glucose production in hepatocytes and enhanced glucose uptake in myocytes. Whereas rapamycin treatment inhibited Akt phosphorylation, PF-4708671 increased Akt phosphorylation in both cell lines. These opposite effects of the mTORC1 and S6K1 inhibitors were also observed in vivo. Indeed, while rapamycin treatment induced glucose intolerance and failed to improve Akt phosphorylation in liver and muscle of HF-fed mice, PF-4708671 treatment improved glucose tolerance and increased Akt phosphorylation in metabolic tissues of these obese mice. CONCLUSIONS/INTERPRETATION Chronic S6K1 inhibition by PF-4708671 improves glucose homeostasis in obese mice through enhanced Akt activation in liver and muscle. Our results suggest that specific S6K1 blockade is a valid pharmacological approach to improve glucose disposal in obese diabetic individuals.
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Affiliation(s)
- Michael Shum
- Department of Medicine, Quebec Heart and Lung Institute, Hôpital Laval, Pavillon Marguerite d'Youville, Room Y4308, 2705 Chemin Ste-Foy, Québec, Canada, G1V 4G5
| | - Kerstin Bellmann
- Department of Medicine, Quebec Heart and Lung Institute, Hôpital Laval, Pavillon Marguerite d'Youville, Room Y4308, 2705 Chemin Ste-Foy, Québec, Canada, G1V 4G5
| | - Philippe St-Pierre
- Department of Medicine, Quebec Heart and Lung Institute, Hôpital Laval, Pavillon Marguerite d'Youville, Room Y4308, 2705 Chemin Ste-Foy, Québec, Canada, G1V 4G5
| | - André Marette
- Department of Medicine, Quebec Heart and Lung Institute, Hôpital Laval, Pavillon Marguerite d'Youville, Room Y4308, 2705 Chemin Ste-Foy, Québec, Canada, G1V 4G5.
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28
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Jerjees DA, Negm OH, Alabdullah ML, Mirza S, Alkaabi M, Hameed MR, Abduljabbar R, Muftah A, Nolan CC, Green AR, Tighe PJ, Band V, Ellis IO, Rakha EA. The mammalian target of rapamycin complex 1 (mTORC1) in breast cancer: the impact of oestrogen receptor and HER2 pathways. Breast Cancer Res Treat 2015; 150:91-103. [PMID: 25701120 DOI: 10.1007/s10549-015-3308-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 02/09/2015] [Indexed: 02/07/2023]
Abstract
The mammalian target of rapamycin complex 1 (mTORC1) is a downstream of the PI3K/Akt pathway which affects cancer development. mTORC1 has many downstream signalling effectors that can enhance different cellular responses. This study aims to investigate the expression of mTORC1 in breast cancer (BC) and correlate it with key clinicopathological and molecular features of BC especially to proteins related to oestrogen receptor (ER) and HER2 pathways in different BC classes. Moreover, mTORC1 expression was assessed in 6 BC cell lines including ER+ and ER- cell lines with and without HER2 transfection. Immunohistochemistry was used to assess the expression of phospho (p) mTORC1 in a large (n = 1300) annotated BC series prepared as tissue microarray. Reverse phase protein array (RPPA) was used to assess its expression in the different BC cell lines. The expression of p-mTORC1 was cytoplasmic with moderate/high expression noted in 44 % of BC. p-mTORC1 expression was associated with clinicopathological variables characteristic of good prognosis. Positive correlation with ER, ER-related proteins AKT, PI3K and luminal differentiation markers were observed in the whole series and in the ER+HER2- subgroup. Association with HER2 was mainly observed in the ER-negative class. RPPA indicated that p-mTORC1 expression was mainly related to ER expression and with better outcome in the Akt positive tumours. p-mTORC1 is associated with good prognostic features. Its expression is related to ER and ER related proteins in addition to AKT and PI3K. Its relation with HER2 expression is mainly seen in the absence of ER expression.
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Affiliation(s)
- Dena A Jerjees
- Division of Cancer and Stem Cells, Department of Histopathology, School of Medicine, Nottingham City Hospital, The University of Nottingham and Nottingham University Hospitals NHS Trust, Nottingham, UK,
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29
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Li Y, Zhang J, Yang C. UNC-51-like kinase 1 blocks S6k1 phosphorylation contributes to neurodegeneration in Parkinson's disease model in vitro. Biochem Biophys Res Commun 2015; 459:196-200. [PMID: 25680463 DOI: 10.1016/j.bbrc.2015.02.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 02/02/2015] [Indexed: 01/30/2023]
Abstract
OBJECTIVE This study was aim to determine the role and underling mechanism of ribosomal protein S6 kinases 1 (S6k1) phosphorylation in Parkinson's disease (PD). METHODS The dopaminergic neuron MN9D was employed and 1-methyl-4-phenylpyridium (MPP) iodide (MPP(+)) was used to generate PD model in vitro. The S6k1 phosphorylation and UNC-51-like kinase 1 (ULK1) protein levels were analyzed by western blot. The ULK1 mRNA level was evaluated by Real-time RT-PCR. The S6k1 threonine 389 (T389) site-directed mutagenesis, the phosphodeficit T389A (threonine to alanine) and the phosphomimetic T389D (threonine to aspartate) were generated to examine the phosphorylation site of S6k1. RESULTS An increase in the ULK1 mRNA and protein levels were detected in the MPP(+)-treated MN9D cells compared to control. ULK1 knockdown increased neuronal cell viability, and enhanced S6k1 phosphorylation. Further investigation demonstrated ULK1 knockdown promoted the S6k1 T389 phosphorylation in particular. T389A enhanced the viability of MPP iodide-treated MN9D, whereas T389D decreased the cell viability. CONCLUSION ULK1 acts to inhibit S6k1 phosphorylation at T389, leading to MN9D viability reduction under MPP(+) treatment. These results provide evidence for a novel mechanism by which the ULK1 inhibit S6k1 T389 phosphorylation contributes to neurodegeneration in MPP(+) treated-MN9D, and suggests a new therapeutic strategy for PD.
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Affiliation(s)
- Yongle Li
- Graduate School of Tianjin Medical University, 22 Qixiangtai Road, Tianjin 300070, China.
| | - Jun Zhang
- Department of Nerve Internal Medicine, Jingmen No.2 People's Hospital, Xiangshan Road, Jingmen 448000, China
| | - Chunxiang Yang
- Department of Nerve Internal Medicine, Jingmen No.2 People's Hospital, Xiangshan Road, Jingmen 448000, China
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Phosphorylation of ribosomal protein S6 kinase 1 at Thr421/Ser424 and dephosphorylation at Thr389 regulates SP600125-induced polyploidization of megakaryocytic cell lines. PLoS One 2014; 9:e114389. [PMID: 25486532 PMCID: PMC4259319 DOI: 10.1371/journal.pone.0114389] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Accepted: 11/07/2014] [Indexed: 11/19/2022] Open
Abstract
Megakaryocytes (MKs) are one of the few cell types that become polyploid; however, the mechanisms by which these cells are designated to become polyploid are not fully understood. In this investigation, we successfully established two relatively synchronous polyploid cell models by inducing Dami and CMK cells with SP600125. We found that SP600125 induced the polyploidization of Dami and CMK cells, concomitant with the phosphorylation of ribosomal protein S6 kinase 1 (S6K1) at Thr421/Ser424 and dephosphorylation at Thr389. The polyploidization was partially blocked by H-89, a cAMP-dependent protein kinase (PKA) inhibitor, through direct binding to S6K1, leading to dephosphorylation at Thr421/Ser424 and phosphorylation at Thr389, independent of PKA. Overexpression of a rapamycin-resistant mutant of S6K1 further enhanced the inhibitory effect of LY294002 on the SP600125-induced polyploidization of Dami and CMK cells. SP600125 also induced the polyploidization of Meg-01 cells, which are derived from a patient with chronic myelogenous leukemia, without causing a significant change in S6K1 phosphorylation. Additionally, SP600125 induced the polyploidization of HEL cells, which are derived from a patient with erythroleukemia, and phosphorylation at Thr389 of S6K1 was detected. However, the polyploidization of both Meg-01 cells and HEL cells as a result of SP600125 treatment was lower than that of SP600125-induced Dami and CMK cells, and it was not blocked by H-89 despite the increased phosphorylation of S6K1 at Thr389 in both cell lines in response to H-89. Given that the Dami and CMK cell lines were derived from patients with acute megakaryocytic leukemia (AMKL) and expressed high levels of platelet-specific antigens, our data suggested that SP600125-induced polyploidization is cell-type specific, that these cell lines were more differentiated, and that phosphorylation at Thr421/Ser424 and dephosphorylation at Thr389 of S6K1 may play an important role in the SP600125-induced polyploidization of these cell lines synergistically with other signaling pathways.
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Doscas ME, Williamson AJ, Usha L, Bogachkov Y, Rao GS, Xiao F, Wang Y, Ruby C, Kaufman H, Zhou J, Williams JW, Li Y, Xu X. Inhibition of p70 S6 kinase (S6K1) activity by A77 1726 and its effect on cell proliferation and cell cycle progress. Neoplasia 2014; 16:824-34. [PMID: 25379019 PMCID: PMC4212247 DOI: 10.1016/j.neo.2014.08.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 08/13/2014] [Accepted: 08/15/2014] [Indexed: 11/16/2022] Open
Abstract
Leflunomide is a novel immunomodulatory drug prescribed for treating rheumatoid arthritis. It inhibits the activity of protein tyrosine kinases and dihydroorotate dehydrogenase, a rate-limiting enzyme in the pyrimidine nucleotide synthesis pathway. Here, we report that A77 1726, the active metabolite of leflunomide, inhibited the phosphorylation of ribosomal protein S6 and two other substrates of S6K1, insulin receptor substrate-1 and carbamoyl phosphate synthetase 2, in an A375 melanoma cell line. A77 1726 increased the phosphorylation of AKT, p70 S6 (S6K1), ERK1/2, and MEK through the feedback activation of the IGF-1 receptor–mediated signaling pathway. Invitro kinase assay revealed that leflunomide and A77 1726 inhibited S6K1 activity with IC50 values of approximately 55 and 80 μM, respectively. Exogenous uridine partially blocked A77 1726–induced inhibition of A375 cell proliferation. S6K1 knockdown led to the inhibition of A375 cell proliferation but did not potentiate the antiproliferative effect of A77 1726. A77 1726 stimulated bromodeoxyuridine incorporation in A375 cells but arrested the cell cycle in the S phase, which was reversed by addition of exogenous uridine or by MAP kinase pathway inhibitors but not by rapamycin and LY294002 (a phosphoinositide 3-kinase inhibitor). These observations suggest that A77 1726 accelerates cell cycle entry into the S phase through MAP kinase activation and that pyrimidine nucleotide depletion halts the completion of the cell cycle. Our study identified a novel molecular target of A77 1726 and showed that the inhibition of S6K1 activity was in part responsible for its antiproliferative activity. Our study also provides a novel mechanistic insight into A77 1726–induced cell cycle arrest in the S phase.
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Affiliation(s)
- Michelle E Doscas
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL 60612
| | | | - Lydia Usha
- Section of Hematology/Oncology, Department of Internal Medicine, Rush University Medical Center, Chicago, IL 60612
| | - Yedida Bogachkov
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL 60612
| | - Geetha S Rao
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL 60612
| | - Fei Xiao
- Cinkate Corporation, Oak Park, IL 60302
| | - Yimin Wang
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL 60612
| | - Carl Ruby
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL 60612 ; Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612
| | - Howard Kaufman
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL 60612 ; Department of Immunology/Microbiology, Rush University Medical Center, Chicago, IL 60612
| | - Jingsong Zhou
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, IL 60612
| | | | - Yi Li
- Baylor College of Medicine, Lester and Sue Smith Breast Center, Department of Molecular and Cell Biology, Houston, TX 77030
| | - Xiulong Xu
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL 60612 ; Department of General Surgery, Rush University Medical Center, Chicago, IL 60612
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Fonseca BD, Smith EM, Yelle N, Alain T, Bushell M, Pause A. The ever-evolving role of mTOR in translation. Semin Cell Dev Biol 2014; 36:102-12. [PMID: 25263010 DOI: 10.1016/j.semcdb.2014.09.014] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 09/12/2014] [Accepted: 09/15/2014] [Indexed: 02/06/2023]
Abstract
Control of translation allows for the production of stoichiometric levels of each protein in the cell. Attaining such a level of fine-tuned regulation of protein production requires the coordinated temporal and spatial control of numerous cellular signalling cascades impinging on the various components of the translational machinery. Foremost among these is the mTOR signalling pathway. The mTOR pathway regulates both the initiation and elongation steps of protein synthesis through the phosphorylation of numerous translation factors, while simultaneously ensuring adequate folding of nascent polypeptides through co-translational degradation of misfolded proteins. Perhaps most remarkably, mTOR is also a key regulator of the synthesis of ribosomal proteins and translation factors themselves. Two seminal studies have recently shown in translatome analysis that the mTOR pathway preferentially regulates the translation of mRNAs encoding ribosomal proteins and translation factors. Therefore, the role of the mTOR pathway in the control of protein synthesis extends far beyond immediate translational control. By controlling ribosome production (and ultimately ribosome availability), mTOR is a master long-term controller of protein synthesis. Herein, we review the literature spanning the early discoveries of mTOR on translation to the latest advances in our understanding of how the mTOR pathway controls the synthesis of ribosomal proteins.
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Affiliation(s)
- Bruno D Fonseca
- Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, ON K1H 8L1, Canada.
| | - Ewan M Smith
- MRC Toxicology Unit, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK
| | - Nicolas Yelle
- Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, ON K1H 8L1, Canada
| | - Tommy Alain
- Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, ON K1H 8L1, Canada
| | - Martin Bushell
- MRC Toxicology Unit, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK
| | - Arnim Pause
- Goodman Cancer Research Centre, Department of Biochemistry, McGill University, Montreal, QC H3A 1A3, Canada.
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Manlin W, Wenlei B, Xiyan H, Xu Z, Yanfeng W, Zhigang W. Molecular Characterization and Expression Analysis of S6K1 in Cashmere Goats (Capra hircus). ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2014; 26:1057-64. [PMID: 25049885 PMCID: PMC4093223 DOI: 10.5713/ajas.2012.12710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 03/07/2013] [Accepted: 02/17/2013] [Indexed: 11/27/2022]
Abstract
p70 ribosomal S6 kinase (p70S6K) can integrate nutrient and growth factor signals to promote cell growth and survival. We report our molecular characterization of the complementary DNA (cDNA) that encodes the goat p70S6K gene 40S ribosomal S6 kinase 1 (S6K1) (GenBank accession GU144017) and its 3′ noncoding sequence in Inner Mongolia Cashmere goats (Capra hircus). Goat S6K1 cDNA was 2,272 bp and include an open reading frame (ORF) of 1,578 bp, corresponding to a polypeptide of 525 amino acids, and a 694-residue 3′ noncoding sequence with a polyadenylation signal at nucleotides 2,218 to 2,223. The relative abundance of S6K1 mRNA was measured by real-time PCR in 6 tissues, and p70S6K expression was examined by immunohistochemistry in heart and testis. The phosphorylation of p70S6K is regulated by mitogen-activated protein kinase (MAPK) signaling in fetal fibroblasts.
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Affiliation(s)
- Wu Manlin
- College of Life Science, Inner Mongolia University, Hohhot, 010021, China
| | - Bao Wenlei
- College of Life Science, Inner Mongolia University, Hohhot, 010021, China
| | - Hao Xiyan
- College of Life Science, Inner Mongolia University, Hohhot, 010021, China
| | - Zheng Xu
- College of Life Science, Inner Mongolia University, Hohhot, 010021, China
| | - Wang Yanfeng
- College of Life Science, Inner Mongolia University, Hohhot, 010021, China
| | - Wang Zhigang
- College of Life Science, Inner Mongolia University, Hohhot, 010021, China
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Shrivastav A, Bruce M, Jaksic D, Bader T, Seekallu S, Penner C, Nugent Z, Watson P, Murphy L. The mechanistic target for rapamycin pathway is related to the phosphorylation score for estrogen receptor-α in human breast tumors in vivo. Breast Cancer Res 2014; 16:R49. [PMID: 24887419 PMCID: PMC4076628 DOI: 10.1186/bcr3660] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 05/02/2014] [Indexed: 01/18/2023] Open
Abstract
INTRODUCTION A phosphorylation score for estrogen receptor-alpha (ERα), called P7 score, was shown previously to be an independent prognostic factor in breast cancer patients treated with tamoxifen. Since mechanistic target of rapamycin (mTOR) activation is implicated in resistance to endocrine therapy in breast cancer we determined whether mechanistic target of rapamycin complex 1 (mTORC1) activation, measured by phosphorylation on S2448 (p-mTOR), was associated with the P7-score and/or clinical outcome in the same cohort. METHODS mTOR phosphorylation status was determined at S2448 residue in vivo by immunohistochemistry in a cohort of more than 400 well-characterized ERα positive breast tumors. MCF7 cells were treated with estrogen and activation of mTOR pathway was determined by Western blotting. RESULTS Contrary to earlier reports, p-mTOR expression, measured by immunohistochemistry, was negatively associated with size and nodal status. Additionally, p-S2448 mTOR expression was positively correlated with p-S118- ERα, p-S167-ERα and p-S282-ERα but negatively correlated with p-T311- ERα. Consistent with these, p-S2448 mTOR was negatively associated with P7-score and was significantly associated with overall survival (OS) (hazard ratio (HR) = 0.61, P = 0.028, 95% confidence interval (CI) 0.39 to 0.95, n = 337) and relapse-free survival (HR = 0.58, P = 0.0032, 95% CI 0.41 to 0.83, n = 337) following univariate but not multivariate analysis. Furthermore, we show that estrogen can regulate phosphorylation of mTOR and its down stream target p70S6 kinase. Additionally, recombinant mTOR can phosphorylate ERα in vitro. CONCLUSIONS These data suggest that in breast tumors where there is intact estrogen regulated signaling, mTOR is regulated by estrogen and therefore associated with an increased likelihood of responsiveness to endocrine therapy.
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Burkhalter MD, Fralish GB, Premont RT, Caron MG, Philipp M. Grk5l controls heart development by limiting mTOR signaling during symmetry breaking. Cell Rep 2013; 4:625-32. [PMID: 23972986 DOI: 10.1016/j.celrep.2013.07.036] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Revised: 06/27/2013] [Accepted: 07/25/2013] [Indexed: 11/29/2022] Open
Abstract
The correct asymmetric placement of inner organs is termed situs solitus and is determined early during development. Failure in symmetry breaking results in conditions ranging from randomized organ arrangement to a complete mirror image, often accompanied by severe congenital heart defects (CHDs). We found that the zebrafish homolog of mammalian G protein-coupled receptor kinase 5 (GRK5) employs noncanonical, receptor-independent functions to secure symmetry breaking. Knockdown of GRK5's closest homolog in zebrafish embryos, Grk5l, is sufficient to randomize cardiac looping and left-right asymmetry. Mechanistically, we found that loss of GRK5 increases mammalian target of rapamycin complex 1 (mTORC1) activity. This causes elongation of motile cilia in the organ of laterality, a consequence that is known to be sufficient to trigger aberrant organ arrangement. By fine-tuning mTORC1, GRK5 thus serves an unanticipated function during early development, besides its well-characterized role in the adult heart. These findings could implicate GRK5 as a susceptibility allele for certain cases of CHD.
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Affiliation(s)
- Martin D Burkhalter
- Leibniz Institute for Age Research, Fritz Lippmann Institute, 07745 Jena, Germany
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Phosphorylation of nuclear and cytoplasmic pools of ribosomal protein S6 during cell cycle progression. Amino Acids 2012; 44:1233-40. [PMID: 23255058 DOI: 10.1007/s00726-012-1445-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 12/07/2012] [Indexed: 10/27/2022]
Abstract
Of all known ribosomal proteins, the 40S ribosomal protein S6 is by far the most extensively studied. Still, little is known about some basic aspects of S6 regulation including its cell cycle-related expression and localization. Using a flow cytometric single cell approach applied to whole cells and isolated nuclei, we monitored nucleocytoplasmic expression of total and S240/4 phosphorylated S6 during unperturbed cell cycle progression, providing first evidence for a S6-specific spatiotemporal pattern and its deregulation under conditions of hyperactivated mTOR.
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Iadevaia V, Zhang Z, Jan E, Proud CG. mTOR signaling regulates the processing of pre-rRNA in human cells. Nucleic Acids Res 2011; 40:2527-39. [PMID: 22121221 PMCID: PMC3315323 DOI: 10.1093/nar/gkr1040] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Signaling through the mammalian target of rapamycin, complex 1 (mTORC1), positively regulates the transcription of ribosomal RNA (rRNA) and the synthesis of ribosomal proteins, thereby promoting the complex process of ribosome biogenesis. The major rRNAs are transcribed as a single precursor, which must be processed to create the 5.8S, 18S and 28S rRNAs. We used a new non-radioactive labeling approach to study the effects of rapamycin, an inhibitor of mTORC1, on rRNA synthesis. Rapamycin not only impaired synthesis of new 18S, 28S or 5S rRNA but also induced their decay. This prompted us to examine the effects of rapamycin on rRNA processing. We show that rapamycin also interferes with the processing events that generate 18S and 28S rRNA. rRNA transcription and processing occur in regions of the nucleus known as nucleoli. We find that the mTORC1 components raptor and mTOR are both present in nucleoli, where they may regulate rRNA maturation events. While rapamycin has no effect on overall nucleolar morphology or its proteome, it does induce loss of mTOR and raptor from them. These data show that mTORC1 is located in nucleoli where it acts to regulate events involved in ribosome biogenesis including the maturation of rRNA molecules.
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