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Chen Y, Li P, Chen X, Yan R, Zhang Y, Wang M, Qin X, Li S, Zheng C, You F, Li T, Liu Y. Endoplasmic reticulum-mitochondrial calcium transport contributes to soft extracellular matrix-triggered mitochondrial dynamics and mitophagy in breast carcinoma cells. Acta Biomater 2023; 169:192-208. [PMID: 37541606 DOI: 10.1016/j.actbio.2023.07.060] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 07/03/2023] [Accepted: 07/28/2023] [Indexed: 08/06/2023]
Abstract
Although mitochondrial morphology and function are considered to be closely related to matrix stiffness-driven tumor progression, it remains poorly understood how extracellular matrix (ECM) stiffness affects mitochondrial dynamics and mitophagy. Here, we found that soft substrate triggered calcium transport by increasing endoplasmic reticulum (ER) calcium release and mitochondrial (MITO) calcium uptake. ER-MITO calcium transport promoted the recruitment of dynamin-related protein 1 (Drp1) to mitochondria and phosphorylation at the serine 616 site, which induced mitochondrial fragmentation and Parkin/PINK1-mediated mitophagy. Furthermore, in vivo experiments demonstrated that soft ECM enhanced calcium levels in tumor tissue, Drp1 activity was required for soft ECM-induced mitochondrial dynamics impairment, and inhibition of Drp1 activity enhanced soft ECM-induced tumor necrosis. In conclusion, we revealed a new mechanism whereby ER-MITO calcium transport regulated mitochondrial dynamics and mitophagy through Drp1 translocation in response to soft substrates. These findings provide valuable insights into ECM stiffness as a potential target for antitumor therapy. STATEMENT OF SIGNIFICANCE: Here, we examined the relationship between substrate stiffness and mitochondrial dynamics by using polyacrylamide (PAA) substrates to simulate the stages of breast cancer or BAPN to reduce tumor tissue stiffness. The results elucidated that soft substrate triggered the recruitment of DRP1 and subsequent mitochondrial fission and mitophagy by ER-MITO calcium transport. Furthermore, mitophagy partly attenuated soft ECM-mediated tumor tissue necrosis and contributed to tumor survival in vivo. Our discoveries revealed the molecular mechanisms by which mechanical stimulation regulates mitochondrial dynamics, providing valuable insights into ECM stiffness as a target for anti-tumor approaches, which could be beneficial for both biomechanics research and clinical applications.
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Affiliation(s)
- Yu Chen
- Department of Pharmacy, Personalized Drug Therapy Key Laboratory of Sichuan Province, Sichuan Provincial People's Hospital, and School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, PR China
| | - Ping Li
- Department of Pharmacy, Personalized Drug Therapy Key Laboratory of Sichuan Province, Sichuan Provincial People's Hospital, and School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, PR China
| | - Xiangyan Chen
- Department of Pharmacy, Personalized Drug Therapy Key Laboratory of Sichuan Province, Sichuan Provincial People's Hospital, and School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, PR China
| | - Ran Yan
- Department of Pharmacy, Personalized Drug Therapy Key Laboratory of Sichuan Province, Sichuan Provincial People's Hospital, and School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, PR China
| | - Yixi Zhang
- Department of Pharmacy, Personalized Drug Therapy Key Laboratory of Sichuan Province, Sichuan Provincial People's Hospital, and School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, PR China
| | - Meng Wang
- Department of Pharmacy, Personalized Drug Therapy Key Laboratory of Sichuan Province, Sichuan Provincial People's Hospital, and School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, PR China
| | - Xiang Qin
- Department of Pharmacy, Personalized Drug Therapy Key Laboratory of Sichuan Province, Sichuan Provincial People's Hospital, and School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, PR China
| | - Shun Li
- Department of Pharmacy, Personalized Drug Therapy Key Laboratory of Sichuan Province, Sichuan Provincial People's Hospital, and School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, PR China
| | - Chuan Zheng
- TCM Regulating Metabolic Diseases Key Laboratory of Sichuan Province, Hospital of Chengdu University of Traditional Chinese Medicine, No. 39 Shi-er-qiao Road, Chengdu 610072, Sichuan, PR China
| | - Fengming You
- TCM Regulating Metabolic Diseases Key Laboratory of Sichuan Province, Hospital of Chengdu University of Traditional Chinese Medicine, No. 39 Shi-er-qiao Road, Chengdu 610072, Sichuan, PR China
| | - Tingting Li
- Department of Pharmacy, Personalized Drug Therapy Key Laboratory of Sichuan Province, Sichuan Provincial People's Hospital, and School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, PR China.
| | - Yiyao Liu
- Department of Pharmacy, Personalized Drug Therapy Key Laboratory of Sichuan Province, Sichuan Provincial People's Hospital, and School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, PR China; TCM Regulating Metabolic Diseases Key Laboratory of Sichuan Province, Hospital of Chengdu University of Traditional Chinese Medicine, No. 39 Shi-er-qiao Road, Chengdu 610072, Sichuan, PR China.
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Ali ES, Chakrabarty B, Ramproshad S, Mondal B, Kundu N, Sarkar C, Sharifi-Rad J, Calina D, Cho WC. TRPM2-mediated Ca 2+ signaling as a potential therapeutic target in cancer treatment: an updated review of its role in survival and proliferation of cancer cells. Cell Commun Signal 2023; 21:145. [PMID: 37337283 DOI: 10.1186/s12964-023-01149-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 04/28/2023] [Indexed: 06/21/2023] Open
Abstract
The transient receptor potential melastatin subfamily member 2 (TRPM2), a thermo and reactive oxygen species (ROS) sensitive Ca2+-permeable cation channel has a vital role in surviving the cell as well as defending the adaptability of various cell groups during and after oxidative stress. It shows higher expression in several cancers involving breast, pancreatic, prostate, melanoma, leukemia, and neuroblastoma, indicating it raises the survivability of cancerous cells. In various cancers including gastric cancers, and neuroblastoma, TRPM2 is known to conserve viability, and several underlying mechanisms of action have been proposed. Transcription factors are thought to activate TRPM2 channels, which is essential for cell proliferation and survival. In normal physiological conditions with an optimal expression of TRPM2, mitochondrial ROS is produced in optimal amounts while regulation of antioxidant expression is carried on. Depletion of TRPM2 overexpression or activity has been shown to improve ischemia-reperfusion injury in organ levels, reduce tumor growth and/or viability of various malignant cancers like breast, gastric, pancreatic, prostate, head and neck cancers, melanoma, neuroblastoma, T-cell and acute myelogenous leukemia. This updated and comprehensive review also analyzes the mechanisms by which TRPM2-mediated Ca2+ signaling can regulate the growth and survival of different types of cancer cells. Based on the discussion of the available data, it can be concluded that TRPM2 may be a unique therapeutic target in the treatment of several types of cancer. Video Abstract.
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Affiliation(s)
- Eunus S Ali
- College of Medicine and Public Health, Flinders University, Bedford Park, 5042, Australia
- Gaco Pharmaceuticals, Dhaka, 1000, Bangladesh
- Present Address: Department of Biochemistry and Molecular Genetics, and Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, 303 E Superior St, Chicago, IL, 60611, USA
| | | | - Sarker Ramproshad
- Department of Pharmacy, Ranada Prasad Shaha University, Narayanganj, 1400, Bangladesh
| | - Banani Mondal
- Department of Pharmacy, Ranada Prasad Shaha University, Narayanganj, 1400, Bangladesh
| | - Neloy Kundu
- Pharmacy Discipline, Khulna University, Khulna, 9208, Bangladesh
| | - Chandan Sarkar
- Department of Pharmacy, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, 8100, Bangladesh
| | | | - Daniela Calina
- Department of Clinical Pharmacy, University of Medicine and Pharmacy of Craiova, Craiova, 200349, Romania.
| | - William C Cho
- Department of Clinical Oncology, Queen Elizabeth Hospital, Kowloon, Hong Kong, China.
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Schoonover MG, Chilson EC, Strome ED. Heterozygous Mutations in Aromatic Amino Acid Synthesis Genes Trigger TOR Pathway Activation in Saccharomyces cerevisiae.. MICROPUBLICATION BIOLOGY 2022; 2022:10.17912/micropub.biology.000685. [PMID: 36468155 PMCID: PMC9713580 DOI: 10.17912/micropub.biology.000685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/02/2022] [Accepted: 11/15/2022] [Indexed: 01/25/2023]
Abstract
The highly conserved complexes of Target of Rapamycin (TORC1 and TORC2) are central regulators to many vital cellular processes including growth and autophagy in response to nutrient availability. Previous research has extensively elucidated exogenous nutrient control on TORC1/TORC2; however, little is known about the potential alteration of nutrient pools from mutations in biosynthesis pathways and their impact on Tor pathway activity. Here, we analyze the impacts of heterozygous mutations in aromatic amino acid biosynthesis genes on TOR signaling via differential expression of genes downstream of TORC1 and autophagy induction for TORC1 and TORC2 activity.
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TOR complex 2 is a master regulator of plasma membrane homeostasis. Biochem J 2022; 479:1917-1940. [PMID: 36149412 PMCID: PMC9555796 DOI: 10.1042/bcj20220388] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 11/17/2022]
Abstract
As first demonstrated in budding yeast (Saccharomyces cerevisiae), all eukaryotic cells contain two, distinct multi-component protein kinase complexes that each harbor the TOR (Target Of Rapamycin) polypeptide as the catalytic subunit. These ensembles, dubbed TORC1 and TORC2, function as universal, centrally important sensors, integrators, and controllers of eukaryotic cell growth and homeostasis. TORC1, activated on the cytosolic surface of the lysosome (or, in yeast, on the cytosolic surface of the vacuole), has emerged as a primary nutrient sensor that promotes cellular biosynthesis and suppresses autophagy. TORC2, located primarily at the plasma membrane, plays a major role in maintaining the proper levels and bilayer distribution of all plasma membrane components (sphingolipids, glycerophospholipids, sterols, and integral membrane proteins). This article surveys what we have learned about signaling via the TORC2 complex, largely through studies conducted in S. cerevisiae. In this yeast, conditions that challenge plasma membrane integrity can, depending on the nature of the stress, stimulate or inhibit TORC2, resulting in, respectively, up-regulation or down-regulation of the phosphorylation and thus the activity of its essential downstream effector the AGC family protein kinase Ypk1. Through the ensuing effect on the efficiency with which Ypk1 phosphorylates multiple substrates that control diverse processes, membrane homeostasis is maintained. Thus, the major focus here is on TORC2, Ypk1, and the multifarious targets of Ypk1 and how the functions of these substrates are regulated by their Ypk1-mediated phosphorylation, with emphasis on recent advances in our understanding of these processes.
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Kaur J, Goldsmith J, Tankka A, Bustamante Eguiguren S, Gimenez AA, Vick L, Debnath J, Vlahakis A. Atg32-dependent mitophagy sustains spermidine and nitric oxide required for heat-stress tolerance in Saccharomycescerevisiae. J Cell Sci 2021; 134:jcs253781. [PMID: 34096604 PMCID: PMC8214763 DOI: 10.1242/jcs.253781] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 05/06/2021] [Indexed: 11/20/2022] Open
Abstract
In Saccharomyces cerevisiae, the selective autophagic degradation of mitochondria, termed mitophagy, is critically regulated by the adapter protein Atg32. Despite our knowledge about the molecular mechanisms by which Atg32 controls mitophagy, its physiological roles in yeast survival and fitness remains less clear. Here, we demonstrate a requirement for Atg32 in promoting spermidine production during respiratory growth and heat-induced mitochondrial stress. During respiratory growth, mitophagy-deficient yeast exhibit profound heat-stress induced defects in growth and viability due to impaired biosynthesis of spermidine and its biosynthetic precursor S-adenosyl methionine. Moreover, spermidine production is crucial for the induction of cytoprotective nitric oxide (NO) during heat stress. Hence, the re-addition of spermidine to Atg32 mutant yeast is sufficient to both enhance NO production and restore respiratory growth during heat stress. Our findings uncover a previously unrecognized physiological role for yeast mitophagy in spermidine metabolism and illuminate new interconnections between mitophagy, polyamine biosynthesis and NO signaling.
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Bulk autophagy induction and life extension is achieved when iron is the only limited nutrient in Saccharomyces cerevisiae. Biochem J 2021; 478:811-837. [DOI: 10.1042/bcj20200849] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 01/21/2023]
Abstract
We have investigated the effects that iron limitation provokes in Saccharomyces cerevisiae exponential cultures. We have demonstrated that one primary response is the induction of bulk autophagy mediated by TORC1. Coherently, Atg13 became dephosphorylated whereas Atg1 appeared phosphorylated. The signal of iron deprivation requires Tor2/Ypk1 activity and the inactivation of Tor1 leading to Atg13 dephosphorylation, thus triggering the autophagy process. Iron replenishment in its turn, reduces autophagy flux through the AMPK Snf1 and the subsequent activity of the iron-responsive transcription factor, Aft1. This signalling converges in Atg13 phosphorylation mediated by Tor1. Iron limitation promotes accumulation of trehalose and the increase in stress resistance leading to a quiescent state in cells. All these effects contribute to the extension of the chronological life, in a manner totally dependent on autophagy activation.
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Amino acid starvation inhibits autophagy in lipid droplet-deficient cells through mitochondrial dysfunction. Biochem J 2021; 477:3613-3623. [PMID: 32886124 DOI: 10.1042/bcj20200551] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 09/03/2020] [Accepted: 09/04/2020] [Indexed: 12/18/2022]
Abstract
Lipid droplets are ubiquitous organelles in eukaryotes that act as storage sites for neutral lipids. Under normal growth conditions, they are not required in the yeast Saccharomyces cerevisiae. However, recent works have shown that lipid droplets are required for autophagy to proceed in response to nitrogen starvation and that they play an essential role in maintaining ER homeostasis. Autophagy is a major catabolic pathway that helps degradation and recycling of potentially harmful proteins and organelles. It can be pharmacologically induced by rapamycin even in the absence of lipid droplets. Here, we show that amino acid starvation is responsible for autophagy failure in lipid droplet-deficient yeast. It not only fails to induce autophagy but also inhibits rapamycin-induced autophagy. The general amino acid control pathway is not involved in this paradoxical effect of amino acid shortage. We correlate the autophagy failure with mitochondria aggregation and we show that amino acid starvation-induced autophagy is restored in lipid droplet-deficient yeast by increasing mitochondrial biomass physiologically (respiration) or genetically (REG1 deletion). Our results establish a new functional link between lipid droplets, ER and mitochondria during nitrogen starvation-induced autophagy.
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TMBIM6/BI-1 contributes to cancer progression through assembly with mTORC2 and AKT activation. Nat Commun 2020; 11:4012. [PMID: 32782388 PMCID: PMC7419509 DOI: 10.1038/s41467-020-17802-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 07/16/2020] [Indexed: 01/09/2023] Open
Abstract
Transmembrane B cell lymphoma 2-associated X protein inhibitor motif-containing (TMBIM) 6, a Ca2+ channel-like protein, is highly up-regulated in several cancer types. Here, we show that TMBIM6 is closely associated with survival in patients with cervical, breast, lung, and prostate cancer. TMBIM6 deletion or knockdown suppresses primary tumor growth. Further, mTORC2 activation is up-regulated by TMBIM6 and stimulates glycolysis, protein synthesis, and the expression of lipid synthesis genes and glycosylated proteins. Moreover, ER-leaky Ca2+ from TMBIM6, a unique characteristic, is shown to affect mTORC2 assembly and its association with ribosomes. In addition, we identify that the BIA compound, a potentialTMBIM6 antagonist, prevents TMBIM6 binding to mTORC2, decreases mTORC2 activity, and also regulates TMBIM6-leaky Ca2+, further suppressing tumor formation and progression in cancer xenograft models. This previously unknown signaling cascade in which mTORC2 activity is enhanced via the interaction with TMBIM6 provides potential therapeutic targets for various malignancies. TMBIM6, a member of the transmembrane BI-1 motif-containing family of proteins, is overexpressed in many cancer types. Here, the authors show that TMBIM6 regulates AKT activation through mTORC2 assembly and ribosome association and identify an antagonist of TMBIM6 with anti-tumor properties.
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Riggi M, Kusmider B, Loewith R. The flipside of the TOR coin - TORC2 and plasma membrane homeostasis at a glance. J Cell Sci 2020; 133:133/9/jcs242040. [PMID: 32393676 DOI: 10.1242/jcs.242040] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Target of rapamycin (TOR) is a serine/threonine protein kinase conserved in most eukaryote organisms. TOR assembles into two multiprotein complexes (TORC1 and TORC2), which function as regulators of cellular growth and homeostasis by serving as direct transducers of extracellular biotic and abiotic signals, and, through their participation in intrinsic feedback loops, respectively. TORC1, the better-studied complex, is mainly involved in cell volume homeostasis through regulating accumulation of proteins and other macromolecules, while the functions of the lesser-studied TORC2 are only now starting to emerge. In this Cell Science at a Glance article and accompanying poster, we aim to highlight recent advances in our understanding of TORC2 signalling, particularly those derived from studies in yeast wherein TORC2 has emerged as a major regulator of cell surface homeostasis.
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Affiliation(s)
- Margot Riggi
- Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland.,Department of Biochemistry, University of Geneva, Geneva, Switzerland.,Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Beata Kusmider
- Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland.,Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Robbie Loewith
- Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland .,Department of Molecular Biology, University of Geneva, Geneva, Switzerland
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Pervaiz S, Bellot GL, Lemoine A, Brenner C. Redox signaling in the pathogenesis of human disease and the regulatory role of autophagy. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2020; 352:189-214. [DOI: 10.1016/bs.ircmb.2020.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Recent Insights into the Mitochondrial Role in Autophagy and Its Regulation by Oxidative Stress. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:3809308. [PMID: 31781334 PMCID: PMC6875203 DOI: 10.1155/2019/3809308] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 09/06/2019] [Accepted: 10/08/2019] [Indexed: 02/07/2023]
Abstract
Autophagy is a self-digestive process that degrades intracellular components, including damaged organelles, to maintain energy homeostasis and to cope with cellular stress. Autophagy plays a key role during development and adult tissue homeostasis, and growing evidence indicates that this catalytic process also has a direct role in modulating aging. Although autophagy is essentially protective, depending on the cellular context and stimuli, autophagy outcome can lead to either abnormal cell growth or cell death. The autophagic process requires a tight regulation, with cellular events following distinct stages and governed by a wide molecular machinery. Reactive oxygen species (ROS) have been involved in autophagy regulation through multiple signaling pathways, and mitochondria, the main source of endogenous ROS, have emerged as essential signal transducers that mediate autophagy. In the present review, we aim to summarize the regulatory function of mitochondria in the autophagic process, particularly regarding the mitochondrial role as the coordination node in the autophagy signaling pathway, involving mitochondrial oxidative stress, and their participation as membrane donors in the initial steps of autophagosome assembly.
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12
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Ariño J, Velázquez D, Casamayor A. Ser/Thr protein phosphatases in fungi: structure, regulation and function. MICROBIAL CELL 2019; 6:217-256. [PMID: 31114794 PMCID: PMC6506691 DOI: 10.15698/mic2019.05.677] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Reversible phospho-dephosphorylation of proteins is a major mechanism for the control of cellular functions. By large, Ser and Thr are the most frequently residues phosphorylated in eukar-yotes. Removal of phosphate from these amino acids is catalyzed by a large family of well-conserved enzymes, collectively called Ser/Thr protein phosphatases. The activity of these enzymes has an enormous impact on cellular functioning. In this work we pre-sent the members of this family in S. cerevisiae and other fungal species, and review the most recent findings concerning their regu-lation and the roles they play in the most diverse aspects of cell biology.
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Affiliation(s)
- Joaquín Ariño
- Departament de Bioquímica i Biologia Molecular and Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain
| | - Diego Velázquez
- Departament de Bioquímica i Biologia Molecular and Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain
| | - Antonio Casamayor
- Departament de Bioquímica i Biologia Molecular and Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain
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Aufschnaiter A, Büttner S. The vacuolar shapes of ageing: From function to morphology. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:957-970. [PMID: 30796938 DOI: 10.1016/j.bbamcr.2019.02.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 02/13/2019] [Accepted: 02/15/2019] [Indexed: 12/21/2022]
Abstract
Cellular ageing results in accumulating damage to various macromolecules and the progressive decline of organelle function. Yeast vacuoles as well as their counterpart in higher eukaryotes, the lysosomes, emerge as central organelles in lifespan determination. These acidic organelles integrate enzymatic breakdown and recycling of cellular waste with nutrient sensing, storage, signalling and mobilization. Establishing physical contact with virtually all other organelles, vacuoles serve as hubs of cellular homeostasis. Studies in Saccharomyces cerevisiae contributed substantially to our understanding of the ageing process per se and the multifaceted roles of vacuoles/lysosomes in the maintenance of cellular fitness with progressing age. Here, we discuss the multiple roles of the vacuole during ageing, ranging from vacuolar dynamics and acidification as determinants of lifespan to the function of this organelle as waste bin, recycling facility, nutrient reservoir and integrator of nutrient signalling.
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Affiliation(s)
- Andreas Aufschnaiter
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010 Graz, Austria
| | - Sabrina Büttner
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010 Graz, Austria; Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrhenius väg 20C, 106 91 Stockholm, Sweden.
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Bourgoint C, Rispal D, Berti M, Filipuzzi I, Helliwell SB, Prouteau M, Loewith R. Target of rapamycin complex 2-dependent phosphorylation of the coat protein Pan1 by Akl1 controls endocytosis dynamics in Saccharomyces cerevisiae. J Biol Chem 2018; 293:12043-12053. [PMID: 29895620 PMCID: PMC6078453 DOI: 10.1074/jbc.ra117.001615] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 06/04/2018] [Indexed: 12/31/2022] Open
Abstract
Target of rapamycin complex 2 (TORC2) is a widely conserved serine/threonine protein kinase. In the yeast Saccharomyces cerevisiae, TORC2 is essential, playing a key role in plasma membrane homeostasis. In this role, TORC2 regulates diverse processes, including sphingolipid synthesis, glycerol production and efflux, polarization of the actin cytoskeleton, and endocytosis. The major direct substrate of TORC2 is the AGC-family kinase Ypk1. Ypk1 connects TORC2 signaling to actin polarization and to endocytosis via the flippase kinases Fpk1 and Fpk2. Here, we report that Fpk1 mediates TORC2 signaling to control actin polarization, but not endocytosis, via aminophospholipid flippases. To search for specific targets of these flippase kinases, we exploited the fact that Fpk1 prefers to phosphorylate Ser residues within the sequence RXS(L/Y)(D/E), which is present ∼90 times in the yeast proteome. We observed that 25 of these sequences are phosphorylated by Fpk1 in vitro We focused on one sequence hit, the Ark/Prk-family kinase Akl1, as this kinase previously has been implicated in endocytosis. Using a potent ATP-competitive small molecule, CMB4563, to preferentially inhibit TORC2, we found that Fpk1-mediated Akl1 phosphorylation inhibits Akl1 activity, which, in turn, reduces phosphorylation of Pan1 and of other endocytic coat proteins and ultimately contributes to a slowing of endocytosis kinetics. These results indicate that the regulation of actin polarization and endocytosis downstream of TORC2 is signaled through separate pathways that bifurcate at the level of the flippase kinases.
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Affiliation(s)
- Clélia Bourgoint
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), National Center for Competence in Research in Chemical Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Delphine Rispal
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), National Center for Competence in Research in Chemical Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Marina Berti
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), National Center for Competence in Research in Chemical Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Ireos Filipuzzi
- Novartis Institutes for Biomedical Research, Novartis Campus, 4056 Basel, Switzerland
| | - Stephen B Helliwell
- Novartis Institutes for Biomedical Research, Novartis Campus, 4056 Basel, Switzerland
| | - Manoël Prouteau
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), National Center for Competence in Research in Chemical Biology, University of Geneva, 1211 Geneva, Switzerland.
| | - Robbie Loewith
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), National Center for Competence in Research in Chemical Biology, University of Geneva, 1211 Geneva, Switzerland.
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mTORC2 Signaling: A Path for Pancreatic β Cell's Growth and Function. J Mol Biol 2018; 430:904-918. [PMID: 29481838 DOI: 10.1016/j.jmb.2018.02.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 02/14/2018] [Accepted: 02/14/2018] [Indexed: 12/16/2022]
Abstract
The mechanistic target of rapamycin (mTOR) signaling pathway is an evolutionary conserved pathway that senses signals from nutrients and growth factors to regulate cell growth, metabolism and survival. mTOR acts in two biochemically and functionally distinct complexes, mTOR complex 1 (mTORC1) and 2 (mTORC2), which differ in terms of regulatory mechanisms, substrate specificity and functional outputs. While mTORC1 signaling has been extensively studied in islet/β-cell biology, recent findings demonstrate a distinct role for mTORC2 in the regulation of pancreatic β-cell function and mass. mTORC2, a key component of the growth factor receptor signaling, is declined in β cells under diabetogenic conditions and in pancreatic islets from patients with type 2 diabetes. β cell-selective mTORC2 inactivation leads to glucose intolerance and acceleration of diabetes as a result of reduced β-cell mass, proliferation and impaired glucose-stimulated insulin secretion. Thereby, many mTORC2 targets, such as AKT, PKC, FOXO1, MST1 and cell cycle regulators, play an important role in β-cell survival and function. This indicates mTORC2 as important pathway for the maintenance of β-cell homeostasis, particularly to sustain proper β-cell compensatory response in the presence of nutrient overload and metabolic demand. This review summarizes recent emerging advances on the contribution of mTORC2 and its associated signaling on the regulation of glucose metabolism and functional β-cell mass under physiological and pathophysiological conditions in type 2 diabetes.
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Vlahakis A, Lopez Muniozguren N, Powers T. Stress-response transcription factors Msn2 and Msn4 couple TORC2-Ypk1 signaling and mitochondrial respiration to ATG8 gene expression and autophagy. Autophagy 2017; 13:1804-1812. [PMID: 29198169 PMCID: PMC5788474 DOI: 10.1080/15548627.2017.1356949] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Macroautophagy/autophagy is a starvation and stress-induced catabolic process critical for cellular homeostasis and adaptation. Several Atg proteins are involved in the formation of the autophagosome and subsequent degradation of cytoplasmic components, a process termed autophagy flux. Additionally, the expression of several Atg proteins, in particular Atg8, is modulated transcriptionally, yet the regulatory mechanisms involved remain poorly understood. Here we demonstrate that the AGC kinase Ypk1, target of the rapamycin-insensitive TORC2 signaling pathway, controls ATG8 expression by repressing the heterodimeric Zinc-finger transcription factors Msn2 and Msn4. We find that Msn2 and Msn4 promote ATG8 expression downstream of the histone deacetylase complex (HDAC) subunit Ume6, a previously identified negative regulator of ATG8 expression. Moreover, we demonstrate that TORC2-Ypk1 signaling is functionally linked to distinct mitochondrial respiratory complexes. Surprisingly, we find that autophagy flux during amino acid starvation is also dependent upon Msn2-Msn4 activity, revealing a broad role for these transcription factors in the autophagy response.
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Affiliation(s)
- Ariadne Vlahakis
- a Department of Molecular and Cellular Biology , College of Biological Sciences, University of California, Davis , Davis , CA , USA.,b Department of Pathology , University of California, San Francisco , San Francisco , CA , USA
| | - Nerea Lopez Muniozguren
- a Department of Molecular and Cellular Biology , College of Biological Sciences, University of California, Davis , Davis , CA , USA
| | - Ted Powers
- a Department of Molecular and Cellular Biology , College of Biological Sciences, University of California, Davis , Davis , CA , USA
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Niedzwiecka K, Tisi R, Penna S, Lichocka M, Plochocka D, Kucharczyk R. Two mutations in mitochondrial ATP6 gene of ATP synthase, related to human cancer, affect ROS, calcium homeostasis and mitochondrial permeability transition in yeast. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1865:117-131. [PMID: 28986220 DOI: 10.1016/j.bbamcr.2017.10.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 09/15/2017] [Accepted: 10/02/2017] [Indexed: 02/06/2023]
Abstract
The relevance of mitochondrial DNA (mtDNA) mutations in cancer process is still unknown. Since the mutagenesis of mitochondrial genome in mammals is not possible yet, we have exploited budding yeast S. cerevisiae as a model to study the effects of tumor-associated mutations in the mitochondrial MTATP6 gene, encoding subunit 6 of ATP synthase, on the energy metabolism. We previously reported that four mutations in this gene have a limited impact on the production of cellular energy. Here we show that two mutations, Atp6-P163S and Atp6-K90E (human MTATP6-P136S and MTATP6-K64E, found in prostate and thyroid cancer samples, respectively), increase sensitivity of yeast cells both to compounds inducing oxidative stress and to high concentrations of calcium ions in the medium, when Om45p, the component of porin complex in outer mitochondrial membrane (OM), was fused to GFP. In OM45-GFP background, these mutations affect the activation of yeast permeability transition pore (yPTP, also called YMUC, yeast mitochondrial unspecific channel) upon calcium induction. Moreover, we show that calcium addition to isolated mitochondria heavily induced the formation of ATP synthase dimers and oligomers, recently proposed to form the core of PTP, which was slower in the mutants. We show the genetic evidence for involvement of mitochondrial ATP synthase in calcium homeostasis and permeability transition in yeast. This paper is a first to show, although in yeast model organism, that mitochondrial ATP synthase mutations, which accumulate during carcinogenesis process, may be significant for cancer cell escape from apoptosis.
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Affiliation(s)
- Katarzyna Niedzwiecka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Renata Tisi
- Dept. Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy; Milan Center for Neuroscience, Milan, Italy
| | - Sara Penna
- Dept. Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Malgorzata Lichocka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Danuta Plochocka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Roza Kucharczyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland.
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The TORC2-Dependent Signaling Network in the Yeast Saccharomyces cerevisiae. Biomolecules 2017; 7:biom7030066. [PMID: 28872598 PMCID: PMC5618247 DOI: 10.3390/biom7030066] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 08/25/2017] [Accepted: 08/28/2017] [Indexed: 12/21/2022] Open
Abstract
To grow, eukaryotic cells must expand by inserting glycerolipids, sphingolipids, sterols, and proteins into their plasma membrane, and maintain the proper levels and bilayer distribution. A fungal cell must coordinate growth with enlargement of its cell wall. In Saccharomyces cerevisiae, a plasma membrane-localized protein kinase complex, Target of Rapamicin (TOR) complex-2 (TORC2) (mammalian ortholog is mTORC2), serves as a sensor and master regulator of these plasma membrane- and cell wall-associated events by directly phosphorylating and thereby stimulating the activity of two types of effector protein kinases: Ypk1 (mammalian ortholog is SGK1), along with a paralog (Ypk2); and, Pkc1 (mammalian ortholog is PKN2/PRK2). Ypk1 is a central regulator of pathways and processes required for plasma membrane lipid and protein homeostasis, and requires phosphorylation on its T-loop by eisosome-associated protein kinase Pkh1 (mammalian ortholog is PDK1) and a paralog (Pkh2). For cell survival under various stresses, Ypk1 function requires TORC2-mediated phosphorylation at multiple sites near its C terminus. Pkc1 controls diverse processes, especially cell wall synthesis and integrity. Pkc1 is also regulated by Pkh1- and TORC2-dependent phosphorylation, but, in addition, by interaction with Rho1-GTP and lipids phosphatidylserine (PtdSer) and diacylglycerol (DAG). We also describe here what is currently known about the downstream substrates modulated by Ypk1-mediated and Pkc1-mediated phosphorylation.
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