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Lee DJW, Hodzic Kuerec A, Maier AB. Targeting ageing with rapamycin and its derivatives in humans: a systematic review. THE LANCET. HEALTHY LONGEVITY 2024; 5:e152-e162. [PMID: 38310895 DOI: 10.1016/s2666-7568(23)00258-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 11/22/2023] [Accepted: 11/24/2023] [Indexed: 02/06/2024] Open
Abstract
Rapamycin and its derivatives (rapalogs) are inhibitors of mTOR, a major regulator of the ageing process. We aimed to summarise the effects of rapamycin and its derivatives on the severity of ageing-related physiological changes and disease in adults. A search across five databases yielded 18 400 unique articles, resulting in 19 included studies. Rapamycin and its derivatives improved physiological parameters associated with ageing in the immune, cardiovascular, and integumentary systems of healthy individuals or individuals with ageing-related diseases. Overall, no significant effects on the endocrine, muscular, or neurological systems were found. The effects of rapamycin or its derivatives on the respiratory, digestive, renal, and reproductive systems were not assessed. No serious adverse events attributed to rapamycin and its derivatives were reported in healthy individuals; however, there were increased numbers of infections and increases in total cholesterol, LDL cholesterol, and triglycerides in individuals with ageing-related diseases. Future studies should assess the remaining unexamined systems and test the effects of long-term exposure to rapamycin and its derivatives.
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Affiliation(s)
- Deborah J W Lee
- Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Ajla Hodzic Kuerec
- Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Centre for Healthy Longevity, @AgeSingapore National University Health System, Singapore
| | - Andrea B Maier
- Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Centre for Healthy Longevity, @AgeSingapore National University Health System, Singapore; Department of Human Movement Sciences, @AgeAmsterdam, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, Netherlands.
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2
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Foltman M, Sanchez-Diaz A. TOR Complex 1: Orchestrating Nutrient Signaling and Cell Cycle Progression. Int J Mol Sci 2023; 24:15745. [PMID: 37958727 PMCID: PMC10647266 DOI: 10.3390/ijms242115745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/26/2023] [Accepted: 10/27/2023] [Indexed: 11/15/2023] Open
Abstract
The highly conserved TOR signaling pathway is crucial for coordinating cellular growth with the cell cycle machinery in eukaryotes. One of the two TOR complexes in budding yeast, TORC1, integrates environmental cues and promotes cell growth. While cells grow, they need to copy their chromosomes, segregate them in mitosis, divide all their components during cytokinesis, and finally physically separate mother and daughter cells to start a new cell cycle apart from each other. To maintain cell size homeostasis and chromosome stability, it is crucial that mechanisms that control growth are connected and coordinated with the cell cycle. Successive periods of high and low TORC1 activity would participate in the adequate cell cycle progression. Here, we review the known molecular mechanisms through which TORC1 regulates the cell cycle in the budding yeast Saccharomyces cerevisiae that have been extensively used as a model organism to understand the role of its mammalian ortholog, mTORC1.
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Affiliation(s)
- Magdalena Foltman
- Mechanisms and Regulation of Cell Division Research Unit, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, 39011 Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, 39011 Santander, Spain
| | - Alberto Sanchez-Diaz
- Mechanisms and Regulation of Cell Division Research Unit, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, 39011 Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, 39011 Santander, Spain
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3
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Foltman M, Mendez I, Bech-Serra JJ, de la Torre C, Brace JL, Weiss EL, Lucas M, Queralt E, Sanchez-Diaz A. TOR complex 1 negatively regulates NDR kinase Cbk1 to control cell separation in budding yeast. PLoS Biol 2023; 21:e3002263. [PMID: 37647291 PMCID: PMC10468069 DOI: 10.1371/journal.pbio.3002263] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 07/19/2023] [Indexed: 09/01/2023] Open
Abstract
The target of rapamycin (TOR) signalling pathway plays a key role in the coordination between cellular growth and the cell cycle machinery in eukaryotes. The underlying molecular mechanisms by which TOR might regulate events after anaphase remain unknown. We show for the first time that one of the 2 TOR complexes in budding yeast, TORC1, blocks the separation of cells following cytokinesis by phosphorylation of a member of the NDR (nuclear Dbf2-related) protein-kinase family, the protein Cbk1. We observe that TORC1 alters the phosphorylation pattern of Cbk1 and we identify a residue within Cbk1 activation loop, T574, for which a phosphomimetic substitution makes Cbk1 catalytically inactive and, indeed, reproduces TORC1 control over cell separation. In addition, we identify the exocyst component Sec3 as a key substrate of Cbk1, since Sec3 activates the SNARE complex to promote membrane fusion. TORC1 activity ultimately compromises the interaction between Sec3 and a t-SNARE component. Our data indicate that TORC1 negatively regulates cell separation in budding yeast by participating in Cbk1 phosphorylation, which in turn controls the fusion of secretory vesicles transporting hydrolase at the site of division.
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Affiliation(s)
- Magdalena Foltman
- Mechanisms and Regulation of Cell Division Research Unit, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Iván Mendez
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
- Structural Biology of Macromolecular Complexes Research Unit, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, Santander, Spain
| | - Joan J. Bech-Serra
- Josep Carreras Leukaemia Research Institute, IJC Building, Campus ICO-Germans Trias i Pujol, Barcelona, Spain
| | - Carolina de la Torre
- Josep Carreras Leukaemia Research Institute, IJC Building, Campus ICO-Germans Trias i Pujol, Barcelona, Spain
| | - Jennifer L. Brace
- Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, Evanston, Illinois, United States of America
| | - Eric L. Weiss
- Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, Evanston, Illinois, United States of America
| | - María Lucas
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
- Structural Biology of Macromolecular Complexes Research Unit, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, Santander, Spain
| | - Ethel Queralt
- Instituto de Biomedicina de Valencia (IBV-CSIC), Valencia, Spain
| | - Alberto Sanchez-Diaz
- Mechanisms and Regulation of Cell Division Research Unit, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
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4
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Gąssowska-Dobrowolska M, Czapski GA, Cieślik M, Zajdel K, Frontczak-Baniewicz M, Babiec L, Adamczyk A. Microtubule Cytoskeletal Network Alterations in a Transgenic Model of Tuberous Sclerosis Complex: Relevance to Autism Spectrum Disorders. Int J Mol Sci 2023; 24:7303. [PMID: 37108467 PMCID: PMC10138344 DOI: 10.3390/ijms24087303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 04/11/2023] [Accepted: 04/13/2023] [Indexed: 04/29/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is a rare genetic multisystem disorder caused by loss-of-function mutations in the tumour suppressors TSC1/TSC2, both of which are negative regulators of the mammalian target of rapamycin (mTOR) kinase. Importantly, mTOR hyperactivity seems to be linked with the pathobiology of autism spectrum disorders (ASD). Recent studies suggest the potential involvement of microtubule (MT) network dysfunction in the neuropathology of "mTORopathies", including ASD. Cytoskeletal reorganization could be responsible for neuroplasticity disturbances in ASD individuals. Thus, the aim of this work was to study the effect of Tsc2 haploinsufficiency on the cytoskeletal pathology and disturbances in the proteostasis of the key cytoskeletal proteins in the brain of a TSC mouse model of ASD. Western-blot analysis indicated significant brain-structure-dependent abnormalities in the microtubule-associated protein Tau (MAP-Tau), and reduced MAP1B and neurofilament light (NF-L) protein level in 2-month-old male B6;129S4-Tsc2tm1Djk/J mice. Alongside, pathological irregularities in the ultrastructure of both MT and neurofilament (NFL) networks as well as swelling of the nerve endings were demonstrated. These changes in the level of key cytoskeletal proteins in the brain of the autistic-like TSC mice suggest the possible molecular mechanisms responsible for neuroplasticity alterations in the ASD brain.
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Affiliation(s)
- Magdalena Gąssowska-Dobrowolska
- Department of Cellular Signalling, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland
| | - Grzegorz A. Czapski
- Department of Cellular Signalling, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland
| | - Magdalena Cieślik
- Department of Cellular Signalling, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland
| | - Karolina Zajdel
- Electron Microscopy Research Unit, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland
| | - Małgorzata Frontczak-Baniewicz
- Electron Microscopy Research Unit, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland
| | - Lidia Babiec
- Department of Cellular Signalling, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland
| | - Agata Adamczyk
- Department of Cellular Signalling, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego 5, 02-106 Warsaw, Poland
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Yamada C, Morooka A, Miyazaki S, Nagai M, Mase S, Iemura K, Tasnin MN, Takuma T, Nakamura S, Morshed S, Koike N, Mostofa MG, Rahman MA, Sharmin T, Katsuta H, Ohara K, Tanaka K, Ushimaru T. TORC1 inactivation promotes APC/C-dependent mitotic slippage in yeast and human cells. iScience 2022; 25:103675. [PMID: 35141499 PMCID: PMC8814761 DOI: 10.1016/j.isci.2021.103675] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 10/20/2021] [Accepted: 12/20/2021] [Indexed: 12/31/2022] Open
Abstract
Unsatisfied kinetochore-microtubule attachment activates the spindle assembly checkpoint to inhibit the metaphase-anaphase transition. However, some cells eventually override mitotic arrest by mitotic slippage. Here, we show that inactivation of TORC1 kinase elicits mitotic slippage in budding yeast and human cells. Yeast mitotic slippage was accompanied with aberrant aspects, such as degradation of the nucleolar protein Net1, release of phosphatase Cdc14, and anaphase-promoting complex/cyclosome (APC/C)-Cdh1-dependent degradation of securin and cyclin B in metaphase. This mitotic slippage caused chromosome instability. In human cells, mammalian TORC1 (mTORC1) inactivation also invoked mitotic slippage, indicating that TORC1 inactivation-induced mitotic slippage is conserved from yeast to mammalian cells. However, the invoked mitotic slippage in human cells was not dependent on APC/C-Cdh1. This study revealed an unexpected involvement of TORC1 in mitosis and provides information on undesirable side effects of the use of TORC1 inhibitors as immunosuppressants and anti-tumor drugs. Yeast TORC1 inhibition promotes Net1 degradation and Cdc14 release Yeast TORC1 inhibition invokes mitotic slippage in an APC/C-Cdh1-dependent manner Human mTORC1 inhibition also elicits mitotic slippage
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Affiliation(s)
- Chihiro Yamada
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka 422-8021, Japan
| | - Aya Morooka
- Department of Biological Science, Faculty of Science, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Seira Miyazaki
- Department of Biological Science, Faculty of Science, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Masayoshi Nagai
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka 422-8021, Japan.,Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Satoru Mase
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka 422-8021, Japan
| | - Kenji Iemura
- Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Most Naoshia Tasnin
- Graduate School of Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan
| | - Tsuneyuki Takuma
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka 422-8021, Japan
| | - Shotaro Nakamura
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka 422-8021, Japan
| | - Shamsul Morshed
- Graduate School of Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan
| | - Naoki Koike
- Graduate School of Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan
| | - Md Golam Mostofa
- Graduate School of Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan
| | - Muhammad Arifur Rahman
- Graduate School of Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan
| | - Tasnuva Sharmin
- Graduate School of Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan
| | - Haruko Katsuta
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka 422-8021, Japan
| | - Kotaro Ohara
- Department of Biological Science, Faculty of Science, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Kozo Tanaka
- Department of Molecular Oncology, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Takashi Ushimaru
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka 422-8021, Japan.,Department of Biological Science, Faculty of Science, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.,Graduate School of Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka 422-8021, Japan
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6
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Ramaian Santhaseela A, Jayavelu T. Does mTORC1 inhibit autophagy at dual stages?: A possible role of mTORC1 in late-stage autophagy inhibition in addition to its known early-stage autophagy inhibition. Bioessays 2020; 43:e2000187. [PMID: 33165974 DOI: 10.1002/bies.202000187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 10/13/2020] [Accepted: 10/13/2020] [Indexed: 11/09/2022]
Abstract
Extensive studies have attributed the lysosomal localization of the mechanistic target of rapamycin complex 1 (mTORC1) during its activation. However, the exact biological significance of this lysosomal localization of mTORC1 remains ill-defined. Interestingly, findings have shown that localization of the lysosome itself is altered under conditions influencing mTORC1 activity. In this perspective, we hypothesize that the localization of mTORC1 and lysosome could be interconnected in a way that manifests regulation of autophagy that is already under progression at the time of mTORC1 activation. This provides a new possibility for autophagy regulation whose complete mechanistic insights remain to be determined.
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7
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Mitochondrial Stress Tests Using Seahorse Respirometry on Intact Dictyostelium discoideum Cells. Methods Mol Biol 2017; 1407:41-61. [PMID: 27271893 DOI: 10.1007/978-1-4939-3480-5_4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Mitochondria not only play a critical and central role in providing metabolic energy to the cell but are also integral to the other cellular processes such as modulation of various signaling pathways. These pathways affect many aspects of cell physiology, including cell movement, growth, division, differentiation, and death. Mitochondrial dysfunction which affects mitochondrial bioenergetics and causes oxidative phosphorylation defects can thus lead to altered cellular physiology and manifest in disease. The assessment of the mitochondrial bioenergetics can thus provide valuable insights into the physiological state, and the alterations to the state of the cells. Here, we describe a method to successfully use the Seahorse XF(e)24 Extracellular Flux Analyzer to assess the mitochondrial respirometry of the cellular slime mold Dictyostelium discoideum.
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8
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van der Vaart B, Fischböck J, Mieck C, Pichler P, Mechtler K, Medema RH, Westermann S. TORC1 signaling exerts spatial control over microtubule dynamics by promoting nuclear export of Stu2. J Cell Biol 2017; 216:3471-3484. [PMID: 28972103 PMCID: PMC5674874 DOI: 10.1083/jcb.201606080] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 02/14/2017] [Accepted: 08/02/2017] [Indexed: 12/30/2022] Open
Abstract
TORC1 regulates microtubule (MT) dynamics in budding yeast, but the key downstream effectors are unknown. van der Vaart et al. show that TORC1 activity before mitosis promotes phosphorylation of the MT polymerase Stu2 near a nuclear export signal, which leads to the nuclear export of Stu2 and reduced nuclear MT growth. The target of rapamycin complex 1 (TORC1) is a highly conserved multiprotein complex that functions in many cellular processes, including cell growth and cell cycle progression. In this study, we define a novel role for TORC1 as a critical regulator of nuclear microtubule (MT) dynamics in the budding yeast Saccharomyces cerevisiae. This activity requires interactions between EB1 and CLIP-170 plus end–tracking protein (+TIP) family members with the TORC1 subunit Kog1/Raptor, which in turn allow the TORC1 proximal kinase Sch9/S6K1 to regulate the MT polymerase Stu2/XMAP215. Sch9-dependent phosphorylation of Stu2 adjacent to a nuclear export signal prevents nuclear accumulation of Stu2 before cells enter mitosis. Mutants impaired in +TIP–TORC1 interactions or Stu2 nuclear export show increased nuclear but not cytoplasmic MT length and display nuclear fusion, spindle positioning, and elongation kinetics defects. Our results reveal key mechanisms by which TORC1 signaling controls Stu2 localization and thereby contributes to proper MT cytoskeletal organization in interphase and mitosis.
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Affiliation(s)
- Babet van der Vaart
- Research Institute of Molecular Pathology, Vienna Biocenter, Vienna, Austria .,Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam, Netherlands
| | - Josef Fischböck
- Research Institute of Molecular Pathology, Vienna Biocenter, Vienna, Austria
| | - Christine Mieck
- Research Institute of Molecular Pathology, Vienna Biocenter, Vienna, Austria
| | - Peter Pichler
- Research Institute of Molecular Pathology, Vienna Biocenter, Vienna, Austria
| | - Karl Mechtler
- Research Institute of Molecular Pathology, Vienna Biocenter, Vienna, Austria
| | - René H Medema
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam, Netherlands
| | - Stefan Westermann
- Research Institute of Molecular Pathology, Vienna Biocenter, Vienna, Austria .,Department of Molecular Genetics, Faculty of Biology, Center for Medical Biotechnology, University of Duisburg-Essen, Essen, Germany
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9
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Global analysis of serine/threonine and tyrosine protein phosphatase catalytic subunit genes in Neurospora crassa reveals interplay between phosphatases and the p38 mitogen-activated protein kinase. G3-GENES GENOMES GENETICS 2014; 4:349-65. [PMID: 24347630 PMCID: PMC3931568 DOI: 10.1534/g3.113.008813] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Protein phosphatases are integral components of the cellular signaling machinery in eukaryotes, regulating diverse aspects of growth and development. The genome of the filamentous fungus and model organism Neurospora crassa encodes catalytic subunits for 30 protein phosphatase genes. In this study, we have characterized 24 viable N. crassa phosphatase catalytic subunit knockout mutants for phenotypes during growth, asexual development, and sexual development. We found that 91% of the mutants had defects in at least one of these traits, whereas 29% possessed phenotypes in all three. Chemical sensitivity screens were conducted to reveal additional phenotypes for the mutants. This resulted in the identification of at least one chemical sensitivity phenotype for 17 phosphatase knockout mutants, including novel chemical sensitivities for two phosphatase mutants lacking a growth or developmental phenotype. Hence, chemical sensitivity or growth/developmental phenotype was observed for all 24 viable mutants. We investigated p38 mitogen-activated protein kinase (MAPK) phosphorylation profiles in the phosphatase mutants and identified nine potential candidates for regulators of the p38 MAPK. We demonstrated that the PP2C class phosphatase pph-8 (NCU04600) is an important regulator of female sexual development in N. crassa. In addition, we showed that the Δcsp-6 (ΔNCU08380) mutant exhibits a phenotype similar to the previously identified conidial separation mutants, Δcsp-1 and Δcsp-2, that lack transcription factors important for regulation of conidiation and the circadian clock.
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Kogasaka Y, Hoshino Y, Hiradate Y, Tanemura K, Sato E. Distribution and association of mTOR with its cofactors, raptor and rictor, in cumulus cells and oocytes during meiotic maturation in mice. Mol Reprod Dev 2013; 80:334-48. [DOI: 10.1002/mrd.22166] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 02/12/2013] [Indexed: 01/26/2023]
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11
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Malik AR, Urbanska M, Macias M, Skalecka A, Jaworski J. Beyond control of protein translation: what we have learned about the non-canonical regulation and function of mammalian target of rapamycin (mTOR). BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1834:1434-48. [PMID: 23277194 DOI: 10.1016/j.bbapap.2012.12.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Accepted: 12/15/2012] [Indexed: 12/19/2022]
Abstract
Mammalian target of rapamycin (mTOR) is a serine-threonine kinase involved in almost every aspect of mammalian cell function. This kinase was initially believed to control protein translation in response to amino acids and trophic factors, and this function has become a canonical role for mTOR. However, mTOR can form two separate protein complexes (mTORCs). Recent advances clearly demonstrate that both mTORCs can respond to various stimuli and change myriad cellular processes. Therefore, our current view of the cellular roles of TORCs has rapidly expanded and cannot be fully explained without appreciating recent findings about the new modes of mTOR regulation and identification of non-canonical effectors of mTOR that contribute to transcription, cytoskeleton dynamics, and membrane trafficking. This review discusses the molecular details of these newly discovered non-canonical functions that allow mTORCs to control the cellular environment at multiple levels. This article is part of a Special Issue entitled: Inhibitors of Protein Kinases (2012).
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Affiliation(s)
- Anna R Malik
- Laboratory of Molecular and Cellular Neurobiology, International Institute of Molecular and Cell Biology in Warsaw, 4 Ks. Trojdena St., 02-109 Warsaw, Poland
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12
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Alonso A, D'Silva S, Rahman M, Meluh PB, Keeling J, Meednu N, Hoops HJ, Miller RK. The yeast homologue of the microtubule-associated protein Lis1 interacts with the sumoylation machinery and a SUMO-targeted ubiquitin ligase. Mol Biol Cell 2012; 23:4552-66. [PMID: 23034179 PMCID: PMC3510017 DOI: 10.1091/mbc.e12-03-0195] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The two yeast members of the CLIP-170/Bik1p and Lis1/Pac1p families of microtubule-associated proteins are shown to interact with the sumoylation machinery and the STUbL complex Ris1p–Nis1p. Pac1p can be modified by both SUMO and ubiquitin. The She1 regulator of dynactin is identified as a novel inhibitor of Pac1p modification. Microtubules and microtubule-associated proteins are fundamental for multiple cellular processes, including mitosis and intracellular motility, but the factors that control microtubule-associated proteins (MAPs) are poorly understood. Here we show that two MAPs—the CLIP-170 homologue Bik1p and the Lis1 homologue Pac1p—interact with several proteins in the sumoylation pathway. Bik1p and Pac1p interact with Smt3p, the yeast SUMO; Ubc9p, an E2; and Nfi1p, an E3. Bik1p interacts directly with SUMO in vitro, and overexpression of Smt3p and Bik1p results in its in vivo sumoylation. Modified Pac1p is observed when the SUMO protease Ulp1p is inactivated. Both ubiquitin and Smt3p copurify with Pac1p. In contrast to ubiquitination, sumoylation does not directly tag the substrate for degradation. However, SUMO-targeted ubiquitin ligases (STUbLs) can recognize a sumoylated substrate and promote its degradation via ubiquitination and the proteasome. Both Pac1p and Bik1p interact with the STUbL Nis1p-Ris1p and the protease Wss1p. Strains deleted for RIS1 or WSS1 accumulate Pac1p conjugates. This suggests a novel model in which the abundance of these MAPs may be regulated via STUbLs. Pac1p modification is also altered by Kar9p and the dynein regulator She1p. This work has implications for the regulation of dynein's interaction with various cargoes, including its off-loading to the cortex.
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Affiliation(s)
- Annabel Alonso
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
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13
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Abstract
Cell migration is a fundamental process in a wide array of biological and
pathological responses. It is regulated by complex signal transduction pathways
in response to external cues that couple to growth factor and chemokine
receptors. In recent years, the target of rapamycin (TOR) kinase, as part of
either TOR complex 1 (TORC1) or TOR complex 2 (TORC2), has been shown to be an
important signaling component linking external signals to the cytoskeletal
machinery in a variety of cell types and organisms. Thus, these complexes have
emerged as key regulators of cell migration and chemotaxis.
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Affiliation(s)
- Lunhua Liu
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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14
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Tran LT, Wang'ondu RW, Weng JB, Wanjiku GW, Fong CM, Kile AC, Koepp DM, Hood-DeGrenier JK. TORC1 kinase and the S-phase cyclin Clb5 collaborate to promote mitotic spindle assembly and DNA replication in S. cerevisiae. Curr Genet 2010; 56:479-93. [PMID: 20697716 DOI: 10.1007/s00294-010-0316-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 07/26/2010] [Accepted: 07/27/2010] [Indexed: 11/25/2022]
Abstract
The Target of Rapamycin complex 1 (TORC1) is a central regulator of eukaryotic cell growth that is inhibited by the drug rapamycin. In the budding yeast Saccharomyces cerevisiae, translational defects associated with TORC1 inactivation inhibit cell cycle progression at an early stage in G1, but little is known about the possible roles for TORC1 later in the cell cycle. We investigated the rapamycin-hypersensitivity phenotype of cells lacking the S phase cyclin Clb5 (clb5Δ) as a basis for uncovering novel connections between TORC1 and the cell cycle regulatory machinery. Dosage suppression experiments suggested that the clb5Δ rapamycin hypersensitivity reflects a unique Clb5-associated cyclin-dependent kinase (CDK) function that cannot be performed by mitotic cyclins and that also involves motor proteins, particularly the kinesin-like protein Kip3. Synchronized cell experiments revealed rapamycin-induced defects in pre-anaphase spindle assembly and S phase progression that were more severe in clb5Δ than in wild-type cells but no apparent activation of Rad53-dependent checkpoint pathways. Some rapamycin-treated cells had aberrant spindle morphologies, but rapamycin did not cause gross defects in the microtubule cytoskeleton. We propose a model in which TORC1 and Clb5/CDK act coordinately to promote both spindle assembly via a pathway involving Kip3 and S phase progression.
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Affiliation(s)
- Lieu T Tran
- Department of Biological Sciences, Wellesley College, Wellesley, MA 02481, USA
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15
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Doghman M, Wakil AEL, Cardinaud B, Thomas E, Wang J, Zhao W, Peralta-Del Valle MHC, Figueiredo BC, Zambetti GP, Lalli E. Regulation of insulin-like growth factor-mammalian target of rapamycin signaling by microRNA in childhood adrenocortical tumors. Cancer Res 2010; 70:4666-75. [PMID: 20484036 PMCID: PMC2880211 DOI: 10.1158/0008-5472.can-09-3970] [Citation(s) in RCA: 163] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
MicroRNAs (miRNAs) act at the posttranscriptional level to control gene expression in virtually every biological process, including oncogenesis. Here, we report the identification of a set of miRNAs that are differentially regulated in childhood adrenocortical tumors (ACT), including miR-99a and miR-100. Functional analysis of these miRNAs in ACT cell lines showed that they coordinately regulate expression of the insulin-like growth factor-mammalian target of rapamycin (mTOR)-raptor signaling pathway through binding sites in their 3'-untranslated regions. In these cells, the active Ser(2448)-phosphorylated form of mTOR is present only in mitotic cells in association with the mitotic spindle and midbody in the G(2)-M phases of the cell cycle. Pharmacologic inhibition of mTOR signaling by everolimus greatly reduces tumor cell growth in vitro and in vivo. Our results reveal a novel mechanism of regulation of mTOR signaling by miRNAs, and they lay the groundwork for clinical evaluation of drugs inhibiting the mTOR pathway for treatment of adrenocortical cancer.
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Affiliation(s)
- Mabrouka Doghman
- Institut de Pharmacologie Moléculaire et Cellulaire CNRS UMR 6097
- Université de Nice - Sophia Antipolis, Valbonne, France
| | - Abeer EL Wakil
- Institut de Pharmacologie Moléculaire et Cellulaire CNRS UMR 6097
- Université de Nice - Sophia Antipolis, Valbonne, France
| | - Bruno Cardinaud
- Institut de Pharmacologie Moléculaire et Cellulaire CNRS UMR 6097
- Université de Nice - Sophia Antipolis, Valbonne, France
| | - Emilie Thomas
- Programme Carte d’Identité des Tumeurs, Ligue Nationale Contre Le Cancer, Paris, France
| | - Jinling Wang
- Department of Biochemistry, St. Jude Children’s Research Hospital, Memphis TN, USA
| | - Wei Zhao
- Department of Biostatistics, St. Jude Children’s Research Hospital, Memphis TN, USA
| | | | - Bonald C. Figueiredo
- Instituto de Pesquisa Pelé Pequeno Principe and Faculdades Pequeno Principe, Curitiba PR, Brazil
| | - Gerard P. Zambetti
- Department of Biochemistry, St. Jude Children’s Research Hospital, Memphis TN, USA
| | - Enzo Lalli
- Institut de Pharmacologie Moléculaire et Cellulaire CNRS UMR 6097
- Université de Nice - Sophia Antipolis, Valbonne, France
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16
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Gouveia SM, Akhmanova A. Cell and Molecular Biology of Microtubule Plus End Tracking Proteins. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 285:1-74. [DOI: 10.1016/b978-0-12-381047-2.00001-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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17
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Yaba A, Bianchi V, Borini A, Johnson J. A putative mitotic checkpoint dependent on mTOR function controls cell proliferation and survival in ovarian granulosa cells. Reprod Sci 2008; 15:128-38. [PMID: 18276949 DOI: 10.1177/1933719107312037] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The conserved target of rapamycin (TOR) proteins are involved in sensing nutrient levels and/or stress and the resultant control of cell growth, size, and survival. The authors assess mammalian TOR (mTOR) kinase expression in the mouse ovary and also the expression of its cofactors, Raptor, Rictor, and LST8. In granulosa cells, mTOR demonstrates high cytoplasmic/perinuclear expression. The kinase-active serine 2448-phosphorylated form of mTOR (P-mTOR) is present at very high levels during the M-phase. P-mTOR was enriched on or near the mitotic spindle and also near the contractile ring during cytokinesis. Rapamycin inhibition of mTOR resulted in both reduced granulosa cell proliferation and reduced follicle growth in vitro, each in a dose-dependent fashion. Follicles cultured in rapamycin did not undergo atresia. mTOR inhibition results in a reduction in granulosa cell proliferation, supporting a model in which stress and nutritional cues may directly influence ovarian follicle growth.
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Affiliation(s)
- Aylin Yaba
- Department of Obstetrics, Gynecology, & Reproductive Sciences, Yale School of Medicine, New Haven, Connecticut 06510, SA
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18
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Swiech L, Perycz M, Malik A, Jaworski J. Role of mTOR in physiology and pathology of the nervous system. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:116-32. [PMID: 17913600 DOI: 10.1016/j.bbapap.2007.08.015] [Citation(s) in RCA: 257] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2007] [Revised: 08/09/2007] [Accepted: 08/10/2007] [Indexed: 01/04/2023]
Abstract
Mammalian target of rapamycin (mTOR) is a serine-threonine protein kinase that regulates several intracellular processes in response to extracellular signals, nutrient availability, energy status of the cell and stress. mTOR regulates survival, differentiation and development of neurons. Axon growth and navigation, dendritic arborization, as well as synaptogenesis, depend on proper mTOR activity. In adult brain mTOR is crucial for synaptic plasticity, learning and memory formation, and brain control of food uptake. Recent studies reveal that mTOR activity is modified in various pathologic states of the nervous system, including brain tumors, tuberous sclerosis, cortical displasia and neurodegenerative disorders such as Alzheimer's, Parkinson's and Huntington's diseases. This review presents current knowledge about the role of mTOR in the physiology and pathology of the nervous system, with special focus on molecular targets acting downstream of mTOR that potentially contribute to neuronal development, plasticity and neuropathology.
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Affiliation(s)
- Lukasz Swiech
- Laboratory of Molecular and Cellular Neurobiology, International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
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19
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Disruption of Esrom and Ryk identifies the roof plate boundary as an intermediate target for commissure formation. Mol Cell Neurosci 2007; 37:271-83. [PMID: 18060805 DOI: 10.1016/j.mcn.2007.10.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Accepted: 10/10/2007] [Indexed: 01/14/2023] Open
Abstract
Growth cones are guided to their final destination by intermediate targets. Here, we identify intermediate targets and signaling components acting on zebrafish habenula commissural axons. Live imaging establishes that axons pause at the medial habenula before and after crossing the roof plate. esrom mutants axons fail to advance beyond the ipsilateral medial habenula. Tsc2 function is reduced in mutant axons, indicating cell autonomous defects in signaling. Consistent with signaling properties changing outside the roof plate, EphB is surface localized on axon segments within a zone demarcated by the medial habenula. wnt4a is expressed in the medial habenula and morpholino knockdown causes loss of the commissure. Electroporation of truncated Ryk causes axons to reenter the midline after reaching the contralateral habenula. These data identify Esrom as a mediator of growth cone navigation at an intermediate target and underscore the importance of midline boundaries as signaling centers for commissure formation.
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20
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Wang BD, Butylin P, Strunnikov A. Condensin function in mitotic nucleolar segregation is regulated by rDNA transcription. Cell Cycle 2006; 5:2260-7. [PMID: 16969110 PMCID: PMC3225123 DOI: 10.4161/cc.5.19.3292] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Chromosome condensation is established and maintained by the condensin complex. The mechanisms governing loading of condensin onto specific chromosomal sites remain unknown. To elucidate the molecular pathways that determine condensin binding to the nucleolar organizer, a key condensin binding site, we analyzed the properties of condensin-bound sites within the rDNA repeat in budding yeast and demonstrated that the bulk of mitotic condensin binding to rDNA is reduced or eliminated when Pol I transcription is elevated. Conversely, when Pol I transcription is repressed either by rapamycin treatment or by promoter shut-off, condensin binding to rDNA is increased. This novel potential role for constitutive and/or periodic repression of Pol I transcription in rDNA condensin loading is an important factor in determining the segregation proficiency of NOR-containing chromosomes.
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Affiliation(s)
| | | | - Alexander Strunnikov
- Correspondence to: Alexander V. Strunnikov; NIH, NICHD, LGRD; 18T Library Drive, Room 106; Bethesda, Maryland 20892 USA; Tel.: 301.402.8384; Fax: 301.402.1323;
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21
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Strawn LA, True HL. Deletion of RNQ1 gene reveals novel functional relationship between divergently transcribed Bik1p/CLIP-170 and Sfi1p in spindle pole body separation. Curr Genet 2006; 50:347-66. [PMID: 16972090 DOI: 10.1007/s00294-006-0098-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Revised: 08/17/2006] [Accepted: 08/19/2006] [Indexed: 02/03/2023]
Abstract
Spindle pole body (SPB; the microtubule organizing center in yeast) duplication is essential to form a bipolar spindle. The duplicated SPBs must then separate and migrate to opposite sides of the nucleus. We identified a novel functional relationship in SPB separation between the microtubule stabilizing protein Bik1p/CLIP-170 and the SPB half-bridge protein Sfi1p. A genetic interaction between BIK1 and SFI1 was discovered in a synthetic lethal screen using a strain deficient in the prion protein gene RNQ1. RNQ1 deletion reduced expression from the divergently transcribed BIK1, allowing us to identify genetic interactors with bik1. The sfi1-1 bik1 synthetic lethality was suppressed by over-expression of CIK1, KAR1, and PPH21. Genetic analysis indicated that the sfi1-1 bik1 synthetic lethality was unlikely related to the function of Bik1p in the dynein pathway or to defects in spindle position. Furthermore, a sfi1-1 Deltakip2 mutant was viable, suggesting that the Bik1p pool at the cytoplasmic microtubule plus-ends may not be required in sfi1-1. Microscopic examination indicated the sfi1-1 mutant was delayed in SPB duplication, SPB separation, or spindle elongation and the sfi-1 Deltabik1 double mutant arrested with duplicated but unseparated SPBs. These results suggest that Bik1p has a previously uncharacterized function in the separation of duplicated SPBs.
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Affiliation(s)
- Lisa A Strawn
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 S Euclid Ave, Campus Box 8228, St Louis, MO, 63110, USA.
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22
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Jiang X, Yeung RS. Regulation of Microtubule-Dependent Protein Transport by the TSC2/Mammalian Target of Rapamycin Pathway. Cancer Res 2006; 66:5258-69. [PMID: 16707451 DOI: 10.1158/0008-5472.can-05-4510] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Protein transport plays a critical role in the interaction of the cell with its environment. Recent studies have identified TSC1 and TSC2, two tumor suppressor genes involved in tuberous sclerosis complex, as regulators of the mammalian target of rapamycin (mTOR) pathway. Cells deficient in TSC1 or TSC2 possess high levels of Rheb-GTP resulting in constitutive mTOR activation. We have shown previously that the TSC1/TSC2 complex is involved in post-Golgi transport of VSVG and caveolin-1 in mammalian cells. Here, we show that modulation of mTOR activity affects caveolin-1 localization and that this effect is independent of p70S6K. Tsc1- and Tsc2-null cells exhibit abnormal caveolin-1 localization that is accompanied by disorganized microtubules in the subcortical region. Analyses of green fluorescent protein-EB1 and tubulin in live mutant cells suggest a failure of the plus-ends to sense cortical signals and to halt microtubule growth. Down-regulation of CLIP-170, a putative mTOR substrate with microtubule-binding properties, rescued the abnormal microtubule arrangement and caveolin-1 localization in Tsc2-/- cells. Together, these findings highlight a novel role of the TSC2/mTOR pathway in regulating microtubule-dependent protein transport.
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Affiliation(s)
- Xiuyun Jiang
- Department of Surgery, University of Washington, Seattle, Washington 98195, USA
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23
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Miller RK, D'Silva S, Moore JK, Goodson HV. The CLIP-170 orthologue Bik1p and positioning the mitotic spindle in yeast. Curr Top Dev Biol 2006; 76:49-87. [PMID: 17118263 DOI: 10.1016/s0070-2153(06)76002-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Bik1p is the yeast Saccharomyces cerevisiae representative of the CLIP-170 family of microtubule plus-end tracking proteins. Bik1p shares a number of similarities with its mammalian counterpart CLIP-170, including an important role in dynein function. However, Bik1p and CLIP-170 differ in several significant ways, including the mechanisms utilized to track microtubule plus ends. In addition to presenting functional comparisons between Bik1p and CLIP-170, we provide sequence analyses that reveal previously unrecognized similarities between Bik1p and its animal counterparts. We examine in detail what is known about the functions of Bik1p and consider the various roles that Bik1p plays in positioning the yeast mitotic spindle. This chapter also highlights several recent findings, including the contribution of Bik1p to the yeast mating pathway.
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Affiliation(s)
- Rita K Miller
- Department of Biology, University of Rochester Rochester, New York 14627, USA
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24
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Abstract
The dynamic properties of microtubules are regulated by plus-end tracking proteins (+TIPs), which associate with the distal ends of microtubules. Among the +TIPs are cytoplasmic linker proteins (CLIPs), which promote microtubule growth and regulate dynein-dynactin localization, and CLIP-associating proteins (CLASPs), which stabilize specific subsets of microtubules on reception of signalling cues. CLIPs and CLASPs interact and cooperate to direct the microtubule network, thereby regulating cellular asymmetry.
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Affiliation(s)
- Niels Galjart
- Department of Cell Biology and Genetics, Erasmus Medical Centre, P.O. Box 1738, 3000 DR, Rotterdam, The Netherlands.
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25
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Inoki K, Ouyang H, Li Y, Guan KL. Signaling by target of rapamycin proteins in cell growth control. Microbiol Mol Biol Rev 2005; 69:79-100. [PMID: 15755954 PMCID: PMC1082789 DOI: 10.1128/mmbr.69.1.79-100.2005] [Citation(s) in RCA: 251] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Target of rapamycin (TOR) proteins are members of the phosphatidylinositol kinase-related kinase (PIKK) family and are highly conserved from yeast to mammals. TOR proteins integrate signals from growth factors, nutrients, stress, and cellular energy levels to control cell growth. The ribosomal S6 kinase 1 (S6K) and eukaryotic initiation factor 4E binding protein 1(4EBP1) are two cellular targets of TOR kinase activity and are known to mediate TOR function in translational control in mammalian cells. However, the precise molecular mechanism of TOR regulation is not completely understood. One of the recent breakthrough studies in TOR signaling resulted in the identification of the tuberous sclerosis complex gene products, TSC1 and TSC2, as negative regulators for TOR signaling. Furthermore, the discovery that the small GTPase Rheb is a direct downstream target of TSC1-TSC2 and a positive regulator of the TOR function has significantly advanced our understanding of the molecular mechanism of TOR activation. Here we review the current understanding of the regulation of TOR signaling and discuss its function as a signaling nexus to control cell growth during normal development and tumorigenesis.
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Affiliation(s)
- Ken Inoki
- Life Science Institute, University of Michigan Medical School, 5450 Medical Science I Bldg., Ann Arbor, MI 48109-0606, USA
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26
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Linde J, Strauss BH. Pharmacological treatment for prevention of restenosis. Expert Opin Emerg Drugs 2005; 6:281-302. [PMID: 15989527 DOI: 10.1517/14728214.6.2.281] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Coronary artery disease (CAD) is the leading cause of mortality and morbidity among adults in the Western world. Coronary artery bypass grafting and percutaneous coronary interventions (PCI) have gained widespread acceptance for the treatment of symptomatic CAD. There has been an explosive growth worldwide in the utilisation of PCI, such as balloon angioplasty and stenting, which now accounts for over 50% of coronary revascularisation. Despite the popularity of PCI, the problem of recurrent narrowing of the dilated artery (restenosis) continues to vex investigators. In recent years, significant advances have occurred in the understanding of restenosis. Two processes seem to contribute to restenosis: remodelling (vessel size changes) and intimal hyperplasia (vascular smooth muscle cell [VSMC] proliferation and extracellular matrix [ECM] deposition). Despite considerable efforts, pharmacological approaches to decrease restenosis have been largely unsuccessful and the only currently applied modality to reduce the restenosis rate is stenting. However, stenting only prevents remodelling and does not inhibit intimal hyperplasia. Several potential targets for inhibiting restenosis are currently under investigation including platelet activation, the coagulation cascade, VSMC proliferation and migration, and ECM synthesis. In addition, new approaches for local drug therapy, such as drug eluting stents, are currently being evaluated in preclinical and clinical studies. In this article, we critically review the current status of drugs that are being evaluated for restenosis at various stages of development (in vitro, preclinical animal models and human trials).
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Affiliation(s)
- J Linde
- The Roy and Ann Foss Interventional Cardiology Research Program, Terrence Donnelly Heart Center, 30 Bond Street, St. Michael's Hospital, Toronto, Ontario, M5B 1W8, Canada
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27
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Lamas-Maceiras M, Cerdán ME, Lloret A, Freire-Picos MA. Characterization of a gene similar to BIK1 in the yeast Kluyveromyces lactis. Yeast 2004; 21:1067-75. [PMID: 15484289 DOI: 10.1002/yea.1140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
In Saccharomyces cerevisiae, Bik1p is a microtubule plus-end-tracking protein that plays several roles in mitosis and ploidy. KlBik1p (from Kluyveromyces lactis) maintains the same structural-domain organization as does S. cerevisiae Bik1p. As part of its characterization, we constructed a stable klbik1 mutant which is sensitive to benomyl only at 14 degrees C and has a higher frequency of crescent-shaped nuclei than S. cerevisiae bik1 mutants. This phenotype is partially rescued by S. cerevisiae BIK1. Other phenotypes associated with bik1 are not present in the K. lactis mutant. By fusion to GFP we were able to show the functionality of the KlBik1p CAP-Gly domain and found that the fusion protein changes its cellular location during the cell cycle.
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Affiliation(s)
- M Lamas-Maceiras
- Facultad de Ciencias, Dpto. de Biología Celular y Molecular, Universidad de A Coruña, Campus de A Zapateira s/n, 15071 A Coruña, Spain
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28
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Abstract
The study of hereditary tumor syndromes has laid a solid foundation toward understanding the genetic basis of cancer. One of the latest examples comes from the study of tuberous sclerosis complex (TSC). As a member of the phakomatoses, TSC is characterized by the appearance of benign tumors, most notably in the central nervous system, kidney, heart, lung, and skin. While classically described as "hamartomas," the pathology of the lesions has features suggestive of abnormal cellular proliferation, size, differentiation, and migration. Occasionally, tumors progress to become malignant (i.e., renal cell carcinoma). The genetic basis of this disease has been attributed to mutations in one of two unlinked genes, TSC1 and TSC2. Cells undergo bi-allelic inactivation of either gene to give rise to tumors in a classic tumor suppressor "two-hit" paradigm. The functions of the TSC1 and TSC2 gene products, hamartin and tuberin, respectively, have remained ill defined until recently. Genetic, biochemical, and biologic analyses have highlighted their role as negative regulators of the mTOR signaling pathway. Tuberin, serving as a substrate of AKT and AMPK, mediates mTOR activity by coordinating inputs from growth factors and energy availability in the control of cell growth, proliferation, and survival. Emerging evidence also suggests that the TSC 1/2 complex may play a role in modulating the activity of beta-catenin and TGFbeta. These findings provide novel functional links between the TSC genes and other tumor suppressors responsible for Cowden's disease (PTEN), Peutz-Jeghers syndrome (LKB1), and familial polyposis (APC). Common sporadic cancers such as prostate, lung, colon, endometrium, and breast have ties to these genes, highlighting the potential role of the TSC proteins in human cancers. Rapamycin, a specific mTOR inhibitor, has potent antitumoral activities in preclinical models of TSC and is currently undergoing phase I/II clinical studies.
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Affiliation(s)
- Baldwin C Mak
- Department of Surgery, University of Washington, Seattle, Washington 98195, USA
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29
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Tsang CK, Bertram PG, Ai W, Drenan R, Zheng XFS. Chromatin-mediated regulation of nucleolar structure and RNA Pol I localization by TOR. EMBO J 2004; 22:6045-56. [PMID: 14609951 PMCID: PMC275436 DOI: 10.1093/emboj/cdg578] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The target of rapamycin (TOR) protein is a conserved regulator of ribosome biogenesis, an important process for cell growth and proliferation. However, how TOR is involved remains poorly understood. In this study, we find that rapamycin and nutrient starvation, conditions inhibiting TOR, lead to significant nucleolar size reduction in both yeast and mammalian cells. In yeast, this morphological change is accompanied by release of RNA polymerase I (Pol I) from the nucleolus and inhibition of ribosomal DNA (rDNA) transcription. We also present evidence that TOR regulates association of Rpd3-Sin3 histone deacetylase (HDAC) with rDNA chromatin, leading to site-specific deacetylation of histone H4. Moreover, histone H4 hypoacetylation mutations cause nucleolar size reduction and Pol I delocalization, while rpd3Delta and histone H4 hyperacetylation mutations block the nucleolar changes as a result of TOR inhibition. Taken together, our results suggest a chromatin-mediated mechanism by which TOR modulates nucleolar structure, RNA Pol I localization and rRNA gene expression in response to nutrient availability.
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Affiliation(s)
- Chi Kwan Tsang
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110, USA
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30
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Abstract
The mammalian target of rapamycin, mTOR, is a protein Ser-Thr kinase that functions as a central element in a signaling pathway involved in the control of cell growth and proliferation. The activity of mTOR is controlled not only by amino acids, but also by hormones and growth factors that activate the protein kinase Akt. The signaling pathway downstream of Akt leading to mTOR involves the protein products of the genes mutated in tuberous sclerosis, TSC1 and TSC2, and the small guanosine triphosphatase, Rheb. In cells, mTOR is found in a complex with two other proteins, raptor and mLST8. In this review, we describe recent progress in understanding the control of the mTOR signaling pathway and the role of mTOR-interacting proteins.
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Affiliation(s)
- Thurl E Harris
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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31
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Gururaja T, Li W, Catalano S, Bogenberger J, Zheng J, Keller B, Vialard J, Janicot M, Li L, Hitoshi Y, Payan DG, Anderson DC. Cellular Interacting Proteins of Functional Screen-Derived Antiproliferative and Cytotoxic Peptides Discovered Using Shotgun Peptide Sequencing. ACTA ACUST UNITED AC 2003; 10:927-37. [PMID: 14583259 DOI: 10.1016/j.chembiol.2003.09.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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32
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Mason MRJ, Lieberman AR, Latchman DS, Anderson PN. FKBP12 mRNA expression is upregulated by intrinsic CNS neurons regenerating axons into peripheral nerve grafts in the brain. Exp Neurol 2003; 181:181-9. [PMID: 12781991 DOI: 10.1016/s0014-4886(03)00038-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have examined the expression of the immunophilin FKBP12 in adult rat intrinsic CNS neurons stimulated to regenerate axons by the implantation of segments of autologous tibial nerve into the thalamus or cerebellum. After survival times of 3 days to 6 weeks, the brains were fresh-frozen. In some animals the regenerating neurons were retrogradely labelled with cholera toxin subunit B 1 day before they were killed. Sections through the thalamus or cerebellum were used for in situ hybridization with digoxygenin-labelled riboprobes for FKBP12 or immunohistochemistry to detect cholera toxin subunit B-labelled neurons. FKBP12 was constitutively expressed by many neurons, and was very strongly expressed in the hippocampus and by Purkinje cells. Regenerating neurons were found in the thalamic reticular nucleus and deep cerebellar nuclei of animals that received living grafts. Neurons in these nuclei upregulated FKBP12 mRNA; such neurons were most numerous at 3 days post grafting but were most strongly labelled at 2 weeks post grafting. Regenerating neurons identified by retrograde labelling were found to have upregulated FKBP12 mRNA. No upregulation was seen in neurons in animals that received freeze-killed grafts, which do not support axonal regeneration. We conclude that FKBP12 is a regeneration-associated gene in intrinsic CNS neurons.
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Affiliation(s)
- M R J Mason
- Department of Anatomy and Developmental Biology, University College London, Gower Street, UK.
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33
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Abstract
A crowd of proteins seems to have gathered around the plus-ends of microtubules. A rapidly expanding group of proteins known as plus-end tracking proteins (+TIPs) have been identified that seem to be able to 'surf' the dynamic ends of microtubules. Microtubule plus-ends exist in multiple conformational and chemical states. In principle, altering this plus-end microenvironment is an appealing way for regulators such as the +TIPS to control microtubule dynamics; however, specific mechanisms are poorly defined. Here, we focus on new findings addressing the underlying mechanisms of plus-end tracking and the mechanisms by which +TIPS control microtubule dynamics. We review the evidence that plus-end-binding and the control of microtubule dynamics are mechanistically linked. We also consider the possibility that, by studying +TIPs, we might learn more about the dynamic structural changes at the microtubule ends that are at the heart of dynamic instability.
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Affiliation(s)
- Pedro Carvalho
- Departments of Pediatric Oncology, Dana-Farber Cancer Institute and Pediatric Hematology/Oncology, Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
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Choi JH, Bertram PG, Drenan R, Carvalho J, Zhou HH, Zheng XS. The FKBP12-rapamycin-associated protein (FRAP) is a CLIP-170 kinase. EMBO Rep 2002; 3:988-94. [PMID: 12231510 PMCID: PMC1307618 DOI: 10.1093/embo-reports/kvf197] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
CLIP-170/Restin belongs to a family of conserved microtubule (MT)-associated proteins, which are important for MT organization and functions. CLIP-170 is a phosphoprotein and phosphorylation is thought to regulate the binding of CLIP-170 to MTs. However, little is known about the kinase(s) involved. In this study, we show that FKBP12-rapamycin-associated protein (FRAP, also called mTOR/RAFT) interacts with CLIP-170. CLIP-170 is phosphorylated in vivo at multiple sites, including rapamycin-sensitive and -insensitive sites, and is phosphorylated by FRAP in vitro at the rapamycin-sensitive sites. In addition, rapamycin inhibited the ability of CLIP-170 to bind to MTs. Our observations suggest that multiple CLIP-170 kinases are involved in positive and negative control of CLIP-170, and FRAP is a CLIP-170 kinase positively regulating the MT-binding behavior of CLIP-170.
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Affiliation(s)
- Jae H. Choi
- Myriad Proteomics, Inc., 2150 West Dauntless Avenue, Salt Lake City, UT 84116, USA
| | - Paula G. Bertram
- Department of Pathology and Immunology, Washington University School of Medicine, 660 S. Euclid Avenue, St Louis, MO 63110, USA
| | - Ryan Drenan
- Department of Pathology and Immunology, Washington University School of Medicine, 660 S. Euclid Avenue, St Louis, MO 63110, USA
| | - John Carvalho
- Department of Pathology and Immunology, Washington University School of Medicine, 660 S. Euclid Avenue, St Louis, MO 63110, USA
| | - Heather H. Zhou
- Cardiovascular Metabolic Disease Genomics, Pharmacia Corp., Chesterfield, MO 63017, USA
| | - X.F. Steven Zheng
- Department of Pathology and Immunology, Washington University School of Medicine, 660 S. Euclid Avenue, St Louis, MO 63110, USA
- Tel: +1 314 747 1884; Fax: +1 314 747 1887;
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Castedo M, Roumier T, Blanco J, Ferri KF, Barretina J, Tintignac LA, Andreau K, Perfettini JL, Amendola A, Nardacci R, Leduc P, Ingber DE, Druillennec S, Roques B, Leibovitch SA, Vilella-Bach M, Chen J, Este JA, Modjtahedi N, Piacentini M, Kroemer G. Sequential involvement of Cdk1, mTOR and p53 in apoptosis induced by the HIV-1 envelope. EMBO J 2002; 21:4070-80. [PMID: 12145207 PMCID: PMC126138 DOI: 10.1093/emboj/cdf391] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Syncytia arising from the fusion of cells expressing the HIV-1-encoded Env gene with cells expressing the CD4/CXCR4 complex undergo apoptosis following the nuclear translocation of mammalian target of rapamycin (mTOR), mTOR-mediated phosphorylation of p53 on Ser15 (p53(S15)), p53-dependent upregulation of Bax and activation of the mitochondrial death pathway. p53(S15) phosphorylation is only detected in syncytia in which nuclear fusion (karyogamy) has occurred. Karyogamy is secondary to a transient upregulation of cyclin B and a mitotic prophase-like dismantling of the nuclear envelope. Inhibition of cyclin-dependent kinase-1 (Cdk1) prevents karyogamy, mTOR activation, p53(S15) phosphorylation and apoptosis. Neutralization of p53 fails to prevent karyogamy, yet suppresses apoptosis. Peripheral blood mononuclear cells from HIV-1-infected patients exhibit an increase in cyclin B and mTOR expression, correlating with p53(S15) phosphorylation and viral load. Cdk1 inhibition prevents the death of syncytia elicited by HIV-1 infection of primary CD4 lymphoblasts. Thus, HIV-1 elicits a pro-apoptotic signal transduction pathway relying on the sequential action of cyclin B-Cdk1, mTOR and p53.
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Affiliation(s)
| | | | - Julià Blanco
- Centre National de la Recherche Scientifique, UMR1599, Institut Gustave Roussy, 39 rue Camille-Desmoulins, F-94805 Villejuif,
Unité de Pharmacochimie Moléculaire et Structurale, INSERM U266–CNRS UMR860, Université René Descartes (Paris V), F-75005 Paris, France, Institut de Recerca de la SIDA-Caixa, Laboratori de Retrovirologia, Hospital Universitari Germans Trias i Pujol, Universitat Autónoma de Barcelona, Ctra Canyet s/n, 08916 Badalona, Catalonia, Spain, Istituto Nazionale Malattie Infettive ‘L. Spallanzani’, Rome 00149, Department of Biology, University of Rome Tor Vergata, Rome 00133, Italy, Departments of Surgery and Pathology, Children’s Hospital and Harvard Medical School, Enders 1007, 300 Longwood Avenue, Boston, MA 02115 and Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA Corresponding author e-mail:
| | | | - Jordi Barretina
- Centre National de la Recherche Scientifique, UMR1599, Institut Gustave Roussy, 39 rue Camille-Desmoulins, F-94805 Villejuif,
Unité de Pharmacochimie Moléculaire et Structurale, INSERM U266–CNRS UMR860, Université René Descartes (Paris V), F-75005 Paris, France, Institut de Recerca de la SIDA-Caixa, Laboratori de Retrovirologia, Hospital Universitari Germans Trias i Pujol, Universitat Autónoma de Barcelona, Ctra Canyet s/n, 08916 Badalona, Catalonia, Spain, Istituto Nazionale Malattie Infettive ‘L. Spallanzani’, Rome 00149, Department of Biology, University of Rome Tor Vergata, Rome 00133, Italy, Departments of Surgery and Pathology, Children’s Hospital and Harvard Medical School, Enders 1007, 300 Longwood Avenue, Boston, MA 02115 and Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA Corresponding author e-mail:
| | | | | | | | - Alessandra Amendola
- Centre National de la Recherche Scientifique, UMR1599, Institut Gustave Roussy, 39 rue Camille-Desmoulins, F-94805 Villejuif,
Unité de Pharmacochimie Moléculaire et Structurale, INSERM U266–CNRS UMR860, Université René Descartes (Paris V), F-75005 Paris, France, Institut de Recerca de la SIDA-Caixa, Laboratori de Retrovirologia, Hospital Universitari Germans Trias i Pujol, Universitat Autónoma de Barcelona, Ctra Canyet s/n, 08916 Badalona, Catalonia, Spain, Istituto Nazionale Malattie Infettive ‘L. Spallanzani’, Rome 00149, Department of Biology, University of Rome Tor Vergata, Rome 00133, Italy, Departments of Surgery and Pathology, Children’s Hospital and Harvard Medical School, Enders 1007, 300 Longwood Avenue, Boston, MA 02115 and Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA Corresponding author e-mail:
| | - Roberta Nardacci
- Centre National de la Recherche Scientifique, UMR1599, Institut Gustave Roussy, 39 rue Camille-Desmoulins, F-94805 Villejuif,
Unité de Pharmacochimie Moléculaire et Structurale, INSERM U266–CNRS UMR860, Université René Descartes (Paris V), F-75005 Paris, France, Institut de Recerca de la SIDA-Caixa, Laboratori de Retrovirologia, Hospital Universitari Germans Trias i Pujol, Universitat Autónoma de Barcelona, Ctra Canyet s/n, 08916 Badalona, Catalonia, Spain, Istituto Nazionale Malattie Infettive ‘L. Spallanzani’, Rome 00149, Department of Biology, University of Rome Tor Vergata, Rome 00133, Italy, Departments of Surgery and Pathology, Children’s Hospital and Harvard Medical School, Enders 1007, 300 Longwood Avenue, Boston, MA 02115 and Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA Corresponding author e-mail:
| | - Philip Leduc
- Centre National de la Recherche Scientifique, UMR1599, Institut Gustave Roussy, 39 rue Camille-Desmoulins, F-94805 Villejuif,
Unité de Pharmacochimie Moléculaire et Structurale, INSERM U266–CNRS UMR860, Université René Descartes (Paris V), F-75005 Paris, France, Institut de Recerca de la SIDA-Caixa, Laboratori de Retrovirologia, Hospital Universitari Germans Trias i Pujol, Universitat Autónoma de Barcelona, Ctra Canyet s/n, 08916 Badalona, Catalonia, Spain, Istituto Nazionale Malattie Infettive ‘L. Spallanzani’, Rome 00149, Department of Biology, University of Rome Tor Vergata, Rome 00133, Italy, Departments of Surgery and Pathology, Children’s Hospital and Harvard Medical School, Enders 1007, 300 Longwood Avenue, Boston, MA 02115 and Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA Corresponding author e-mail:
| | - Donald E. Ingber
- Centre National de la Recherche Scientifique, UMR1599, Institut Gustave Roussy, 39 rue Camille-Desmoulins, F-94805 Villejuif,
Unité de Pharmacochimie Moléculaire et Structurale, INSERM U266–CNRS UMR860, Université René Descartes (Paris V), F-75005 Paris, France, Institut de Recerca de la SIDA-Caixa, Laboratori de Retrovirologia, Hospital Universitari Germans Trias i Pujol, Universitat Autónoma de Barcelona, Ctra Canyet s/n, 08916 Badalona, Catalonia, Spain, Istituto Nazionale Malattie Infettive ‘L. Spallanzani’, Rome 00149, Department of Biology, University of Rome Tor Vergata, Rome 00133, Italy, Departments of Surgery and Pathology, Children’s Hospital and Harvard Medical School, Enders 1007, 300 Longwood Avenue, Boston, MA 02115 and Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA Corresponding author e-mail:
| | - Sabine Druillennec
- Centre National de la Recherche Scientifique, UMR1599, Institut Gustave Roussy, 39 rue Camille-Desmoulins, F-94805 Villejuif,
Unité de Pharmacochimie Moléculaire et Structurale, INSERM U266–CNRS UMR860, Université René Descartes (Paris V), F-75005 Paris, France, Institut de Recerca de la SIDA-Caixa, Laboratori de Retrovirologia, Hospital Universitari Germans Trias i Pujol, Universitat Autónoma de Barcelona, Ctra Canyet s/n, 08916 Badalona, Catalonia, Spain, Istituto Nazionale Malattie Infettive ‘L. Spallanzani’, Rome 00149, Department of Biology, University of Rome Tor Vergata, Rome 00133, Italy, Departments of Surgery and Pathology, Children’s Hospital and Harvard Medical School, Enders 1007, 300 Longwood Avenue, Boston, MA 02115 and Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA Corresponding author e-mail:
| | - Bernard Roques
- Centre National de la Recherche Scientifique, UMR1599, Institut Gustave Roussy, 39 rue Camille-Desmoulins, F-94805 Villejuif,
Unité de Pharmacochimie Moléculaire et Structurale, INSERM U266–CNRS UMR860, Université René Descartes (Paris V), F-75005 Paris, France, Institut de Recerca de la SIDA-Caixa, Laboratori de Retrovirologia, Hospital Universitari Germans Trias i Pujol, Universitat Autónoma de Barcelona, Ctra Canyet s/n, 08916 Badalona, Catalonia, Spain, Istituto Nazionale Malattie Infettive ‘L. Spallanzani’, Rome 00149, Department of Biology, University of Rome Tor Vergata, Rome 00133, Italy, Departments of Surgery and Pathology, Children’s Hospital and Harvard Medical School, Enders 1007, 300 Longwood Avenue, Boston, MA 02115 and Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA Corresponding author e-mail:
| | | | - Montserrat Vilella-Bach
- Centre National de la Recherche Scientifique, UMR1599, Institut Gustave Roussy, 39 rue Camille-Desmoulins, F-94805 Villejuif,
Unité de Pharmacochimie Moléculaire et Structurale, INSERM U266–CNRS UMR860, Université René Descartes (Paris V), F-75005 Paris, France, Institut de Recerca de la SIDA-Caixa, Laboratori de Retrovirologia, Hospital Universitari Germans Trias i Pujol, Universitat Autónoma de Barcelona, Ctra Canyet s/n, 08916 Badalona, Catalonia, Spain, Istituto Nazionale Malattie Infettive ‘L. Spallanzani’, Rome 00149, Department of Biology, University of Rome Tor Vergata, Rome 00133, Italy, Departments of Surgery and Pathology, Children’s Hospital and Harvard Medical School, Enders 1007, 300 Longwood Avenue, Boston, MA 02115 and Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA Corresponding author e-mail:
| | - Jie Chen
- Centre National de la Recherche Scientifique, UMR1599, Institut Gustave Roussy, 39 rue Camille-Desmoulins, F-94805 Villejuif,
Unité de Pharmacochimie Moléculaire et Structurale, INSERM U266–CNRS UMR860, Université René Descartes (Paris V), F-75005 Paris, France, Institut de Recerca de la SIDA-Caixa, Laboratori de Retrovirologia, Hospital Universitari Germans Trias i Pujol, Universitat Autónoma de Barcelona, Ctra Canyet s/n, 08916 Badalona, Catalonia, Spain, Istituto Nazionale Malattie Infettive ‘L. Spallanzani’, Rome 00149, Department of Biology, University of Rome Tor Vergata, Rome 00133, Italy, Departments of Surgery and Pathology, Children’s Hospital and Harvard Medical School, Enders 1007, 300 Longwood Avenue, Boston, MA 02115 and Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA Corresponding author e-mail:
| | - José A. Este
- Centre National de la Recherche Scientifique, UMR1599, Institut Gustave Roussy, 39 rue Camille-Desmoulins, F-94805 Villejuif,
Unité de Pharmacochimie Moléculaire et Structurale, INSERM U266–CNRS UMR860, Université René Descartes (Paris V), F-75005 Paris, France, Institut de Recerca de la SIDA-Caixa, Laboratori de Retrovirologia, Hospital Universitari Germans Trias i Pujol, Universitat Autónoma de Barcelona, Ctra Canyet s/n, 08916 Badalona, Catalonia, Spain, Istituto Nazionale Malattie Infettive ‘L. Spallanzani’, Rome 00149, Department of Biology, University of Rome Tor Vergata, Rome 00133, Italy, Departments of Surgery and Pathology, Children’s Hospital and Harvard Medical School, Enders 1007, 300 Longwood Avenue, Boston, MA 02115 and Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA Corresponding author e-mail:
| | | | - Mauro Piacentini
- Centre National de la Recherche Scientifique, UMR1599, Institut Gustave Roussy, 39 rue Camille-Desmoulins, F-94805 Villejuif,
Unité de Pharmacochimie Moléculaire et Structurale, INSERM U266–CNRS UMR860, Université René Descartes (Paris V), F-75005 Paris, France, Institut de Recerca de la SIDA-Caixa, Laboratori de Retrovirologia, Hospital Universitari Germans Trias i Pujol, Universitat Autónoma de Barcelona, Ctra Canyet s/n, 08916 Badalona, Catalonia, Spain, Istituto Nazionale Malattie Infettive ‘L. Spallanzani’, Rome 00149, Department of Biology, University of Rome Tor Vergata, Rome 00133, Italy, Departments of Surgery and Pathology, Children’s Hospital and Harvard Medical School, Enders 1007, 300 Longwood Avenue, Boston, MA 02115 and Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA Corresponding author e-mail:
| | - Guido Kroemer
- Centre National de la Recherche Scientifique, UMR1599, Institut Gustave Roussy, 39 rue Camille-Desmoulins, F-94805 Villejuif,
Unité de Pharmacochimie Moléculaire et Structurale, INSERM U266–CNRS UMR860, Université René Descartes (Paris V), F-75005 Paris, France, Institut de Recerca de la SIDA-Caixa, Laboratori de Retrovirologia, Hospital Universitari Germans Trias i Pujol, Universitat Autónoma de Barcelona, Ctra Canyet s/n, 08916 Badalona, Catalonia, Spain, Istituto Nazionale Malattie Infettive ‘L. Spallanzani’, Rome 00149, Department of Biology, University of Rome Tor Vergata, Rome 00133, Italy, Departments of Surgery and Pathology, Children’s Hospital and Harvard Medical School, Enders 1007, 300 Longwood Avenue, Boston, MA 02115 and Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA Corresponding author e-mail:
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Chai B, Hsu JM, Du J, Laurent BC. Yeast RSC function is required for organization of the cellular cytoskeleton via an alternative PKC1 pathway. Genetics 2002; 161:575-84. [PMID: 12072455 PMCID: PMC1462120 DOI: 10.1093/genetics/161.2.575] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
RSC is a 15-protein ATP-dependent chromatin-remodeling complex related to Snf-Swi, the prototypical ATP-dependent nucleosome remodeler in budding yeast. Despite insight into the mechanism by which purified RSC remodels nucleosomes, little is known about the chromosomal targets or cellular pathways in which RSC acts. To better understand the cellular function of RSC, a screen was undertaken for gene dosage suppressors of sth1-3ts, a temperature-sensitive mutation in STH1, which encodes the essential ATPase subunit. Slg1p and Mid2p, two type I transmembrane stress sensors of cell wall integrity that function upstream of protein kinase C (Pkc1p), were identified as multicopy suppressors of sth1-3ts cells. Although the sth1-3ts mutant exhibits defects characteristic of PKC1 pathway mutants (caffeine and staurosporine sensitivities and an osmoremedial phenotype), only upstream components and not downstream effectors of the PKC1-MAP kinase pathway can suppress defects conferred by sth1-3ts, suggesting that RSC functions in an alternative PKC1-dependent pathway. Moreover, sth1-3ts cells display defects in actin cytoskeletal rearrangements and are hypersensitive to the microtubule depolymerizing drug, TBZ; both of these defects can be corrected by the high-copy suppressors. Together, these data reveal an important functional connection between the RSC remodeler and PKC1-dependent signaling in regulating the cellular architecture.
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Affiliation(s)
- Bob Chai
- Department of Microbiology and Immunology and Morse Institute for Molecular Genetics, State University of New York, Brooklyn, New York 11203, USA
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37
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Calastretti A, Bevilacqua A, Ceriani C, Viganò S, Zancai P, Capaccioli S, Nicolin A. Damaged microtubules can inactivate BCL-2 by means of the mTOR kinase. Oncogene 2001; 20:6172-80. [PMID: 11593425 DOI: 10.1038/sj.onc.1204751] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2000] [Revised: 06/14/2001] [Accepted: 06/26/2001] [Indexed: 12/25/2022]
Abstract
Rapamycin, a specific inhibitor of the serine/threonine mTOR kinase, markedly inhibited both cell growth and apoptosis in human B-cell lines. Besides arresting cells in G(1) by increasing p27(kip1), rapamycin tripled the cellular level of the BCL-2 protein. The activity was dose-dependent and specific for the p27(kip1) and BCL-2 proteins. Rapamycin did not affect bcl-2 mRNA although it increased cellular BCL-2 concentration by inhibiting phosphorylation, a mechanism initiating the decay process. To add new insight, we combined rapamycin treatment with treatment by taxol, which, by damaging microtubules, can phosphorylate BCL-2 and activate apoptosis. It was found that the mTOR kinase was activated in cells treated with taxol or with nocodazole although it was inhibited in cells pre-treated with rapamycin. BCL-2 phosphorylation, apoptosis and hyperdiploidy were also inhibited by rapamycin. In contrast, taxol-induced microtubule stabilization or metaphase synchronization were not inhibited by rapamycin. Taken together, these findings indicate that mTOR belongs to the enzymatic cascade that, starting from damaged microtubules, phosphorylates BCL-2. By regulating apoptosis, in addition to the control of a multitude of growth-related pathways, mTOR plays a nodal role in signaling G(1) and G(2)-M events.
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Affiliation(s)
- A Calastretti
- Department of Pharmacology, University of Milan, Via Vanvitelli 32, Milan 20129, Italy
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Schuyler SC, Pellman D. Microtubule "plus-end-tracking proteins": The end is just the beginning. Cell 2001; 105:421-4. [PMID: 11371339 DOI: 10.1016/s0092-8674(01)00364-6] [Citation(s) in RCA: 295] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- S C Schuyler
- Department of Pediatric Oncology, The Dana-Farber Cancer Institute and Pediatric Hematology, The Children's Hospital, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA.
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39
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Liu J, Prickett TD, Elliott E, Meroni G, Brautigan DL. Phosphorylation and microtubule association of the Opitz syndrome protein mid-1 is regulated by protein phosphatase 2A via binding to the regulatory subunit alpha 4. Proc Natl Acad Sci U S A 2001; 98:6650-5. [PMID: 11371618 PMCID: PMC34408 DOI: 10.1073/pnas.111154698] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2001] [Accepted: 03/29/2001] [Indexed: 11/18/2022] Open
Abstract
Opitz syndrome (OS) is a human genetic disease characterized by deformities such as cleft palate that are attributable to defects in embryonic development at the midline. Gene mapping has identified OS mutations within a protein called Mid1. Wild-type Mid1 predominantly colocalizes with microtubules, in contrast to mutant versions of Mid1 that appear clustered in the cytosol. Using yeast two-hybrid screening, we found that the alpha4-subunit of protein phosphatases 2A/4/6 binds Mid1. Epitope-tagged alpha4 coimmunoprecipitated endogenous or coexpressed Mid1 from COS7 cells, and this required only the conserved C-terminal region of alpha4. Localization of Mid1 and alpha4 was influenced by one another in transiently transfected cells. Mid1 could recruit alpha4 onto microtubules, and high levels of alpha4 could displace Mid1 into the cytosol. Metabolic (32)P labeling of cells showed that Mid1 is a phosphoprotein, and coexpression of full-length alpha4 decreased Mid1 phosphorylation, indicative of a functional interaction. Association of green fluorescent protein-Mid1 with microtubules in living cells was perturbed by inhibitors of MAP kinase activation. The conclusion is that Mid1 association with microtubules, which seems important for normal midline development, is regulated by dynamic phosphorylation involving MAP kinase and protein phosphatase that is targeted specifically to Mid1 by alpha4. Human birth defects may result from environmental or genetic disruption of this regulatory cycle.
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Affiliation(s)
- J Liu
- Center for Cell Signaling, University of Virginia School of Medicine, P.O. Box 800577, Charlottesville, VA 22908-0577, USA
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40
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van der Merwe GK, Cooper TG, van Vuuren HJJ. Ammonia regulates VID30 expression and Vid30p function shifts nitrogen metabolism toward glutamate formation especially when Saccharomyces cerevisiae is grown in low concentrations of ammonia. J Biol Chem 2001; 276:28659-66. [PMID: 11356843 PMCID: PMC4384459 DOI: 10.1074/jbc.m102280200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The GATA family proteins Gln3p and Gat1p mediate nitrogen catabolite repression (NCR)-sensitive transcription in Saccharomyces cerevisiae. When cells are cultured with a good nitrogen source (glutamine, ammonia), Gln3p and Gat1p are restricted to the cytoplasm, whereas with a poor nitrogen source (proline), they localize to the nucleus, bind to the GATA sequences of NCR-sensitive gene promoters, and activate transcription. The target of rapamycin-signaling cascade and Ure2p participate in regulating the cellular localization of Gln3p and Gat1p. Rapamycin, a Tor protein inhibitor, like growth with a poor nitrogen source, promotes nuclear localization of Gln3p and Gat1p. gln3 Delta and ure2 Delta mutants are partially resistant and hypersensitive to growth inhibition by rapamycin, respectively. We show that a vid30 Delta is more rapamycin-sensitive than wild type but less so than a ure2 Delta. VID30 expression is modestly NCR-sensitive, responsive to deletion of URE2, and greatly increases in low ammonia medium. Patterns of gene expression in a vid30 Delta suggest that the Vid30p function shifts the balance of nitrogen metabolism toward the production of glutamate, especially when cells are grown in low ammonia. CAN1, DAL4, DAL5, MEP2, DAL1, DAL80, and GDH3 transcription is down-regulated by Vid30p function with proline as the nitrogen source. An effect, however, that could easily be indirect.
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Affiliation(s)
- George K. van der Merwe
- Wine Research Center, Faculty of Agricultural Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Terrance G. Cooper
- Department of Microbiology and Immunology, University of Tennessee, Memphis, Tennessee 38163
| | - Hennie J. J. van Vuuren
- Wine Research Center, Faculty of Agricultural Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- To whom correspondence should be addressed. Tel.: 604-822-0418; Fax: 604-822-5143;
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41
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Abstract
Recent studies have suggested that proteins found at the tips of microtubules in vertebrate cells may play an important role in intracellular membrane transport processes. Evidence from fission yeast indicates that such proteins can also regulate microtubule dynamics.
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Affiliation(s)
- K E Sawin
- Wellcome Trust Centre for Cell Biology, Institute of Cell and Molecular Biology, University of Edinburgh, UK.
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42
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Chan TF, Carvalho J, Riles L, Zheng XF. A chemical genomics approach toward understanding the global functions of the target of rapamycin protein (TOR). Proc Natl Acad Sci U S A 2000; 97:13227-32. [PMID: 11078525 PMCID: PMC27207 DOI: 10.1073/pnas.240444197] [Citation(s) in RCA: 140] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The target of rapamycin protein (TOR) is a highly conserved ataxia telangiectasia-related protein kinase essential for cell growth. Emerging evidence indicates that TOR signaling is highly complex and is involved in a variety of cellular processes. To understand its general functions, we took a chemical genomics approach to explore the genetic interaction between TOR and other yeast genes on a genomic scale. In this study, the rapamycin sensitivity of individual deletion mutants generated by the Saccharomyces Genome Deletion Project was systematically measured. Our results provide a global view of the rapamycin-sensitive functions of TOR. In contrast to conventional genetic analysis, this approach offers a simple and thorough analysis of genetic interaction on a genomic scale and measures genetic interaction at different possible levels. It can be used to study the functions of other drug targets and to identify novel protein components of a conserved core biological process such as DNA damage checkpoint/repair that is interfered with by a cell-permeable chemical compound.
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Affiliation(s)
- T F Chan
- Departments of Pathology and Immunology and Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
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43
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Zhang H, Stallock JP, Ng JC, Reinhard C, Neufeld TP. Regulation of cellular growth by the Drosophila target of rapamycin dTOR. Genes Dev 2000; 14:2712-24. [PMID: 11069888 PMCID: PMC317034 DOI: 10.1101/gad.835000] [Citation(s) in RCA: 484] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The TOR protein kinases (TOR1 and TOR2 in yeast; mTOR/FRAP/RAFT1 in mammals) promote cellular proliferation in response to nutrients and growth factors, but their role in development is poorly understood. Here, we show that the Drosophila TOR homolog dTOR is required cell autonomously for normal growth and proliferation during larval development, and for increases in cellular growth caused by activation of the phosphoinositide 3-kinase (PI3K) signaling pathway. As in mammalian cells, the kinase activity of dTOR is required for growth factor-dependent phosphorylation of p70 S6 kinase (p70(S6K)) in vitro, and we demonstrate that overexpression of p70(S6K) in vivo can rescue dTOR mutant animals to viability. Loss of dTOR also results in cellular phenotypes characteristic of amino acid deprivation, including reduced nucleolar size, lipid vesicle aggregation in the larval fat body, and a cell type-specific pattern of cell cycle arrest that can be bypassed by overexpression of the S-phase regulator cyclin E. Our results suggest that dTOR regulates growth during animal development by coupling growth factor signaling to nutrient availability.
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Affiliation(s)
- H Zhang
- Chiron Corporation, Emeryville, California 94608, USA
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