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Navabi SP, Badreh F, Khombi Shooshtari M, Hajipour S, Moradi Vastegani S, Khoshnam SE. Microglia-induced neuroinflammation in hippocampal neurogenesis following traumatic brain injury. Heliyon 2024; 10:e35869. [PMID: 39220913 PMCID: PMC11365414 DOI: 10.1016/j.heliyon.2024.e35869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 07/25/2024] [Accepted: 08/05/2024] [Indexed: 09/04/2024] Open
Abstract
Traumatic brain injury (TBI) is one of the most causes of death and disability among people, leading to a wide range of neurological deficits. The important process of neurogenesis in the hippocampus, which includes the production, maturation and integration of new neurons, is affected by TBI due to microglia activation and the inflammatory response. During brain development, microglia are involved in forming or removing synapses, regulating the number of neurons, and repairing damage. However, in response to injury, activated microglia release a variety of pro-inflammatory cytokines, chemokines and other neurotoxic mediators that exacerbate post-TBI injury. These microglia-related changes can negatively affect hippocampal neurogenesis and disrupt learning and memory processes. To date, the intracellular signaling pathways that trigger microglia activation following TBI, as well as the effects of microglia on hippocampal neurogenesis, are poorly understood. In this review article, we discuss the effects of microglia-induced neuroinflammation on hippocampal neurogenesis following TBI, as well as the intracellular signaling pathways of microglia activation.
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Affiliation(s)
- Seyedeh Parisa Navabi
- Persian Gulf Physiology Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | | | - Maryam Khombi Shooshtari
- Persian Gulf Physiology Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Somayeh Hajipour
- Persian Gulf Physiology Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Sadegh Moradi Vastegani
- Persian Gulf Physiology Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Seyed Esmaeil Khoshnam
- Persian Gulf Physiology Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
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2
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Radford RAW, Rayner SL, Szwaja P, Morsch M, Cheng F, Zhu T, Widagdo J, Anggono V, Pountney DL, Chung R, Lee A. Identification of phosphorylated tau protein interactors in progressive supranuclear palsy (PSP) reveals networks involved in protein degradation, stress response, cytoskeletal dynamics, metabolic processes, and neurotransmission. J Neurochem 2023; 165:563-586. [PMID: 36847488 PMCID: PMC10953353 DOI: 10.1111/jnc.15796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/27/2023] [Accepted: 02/21/2023] [Indexed: 03/01/2023]
Abstract
Progressive supranuclear palsy (PSP) is a late-onset neurodegenerative disease defined pathologically by the presence of insoluble phosphorylated-Tau (p-Tau) in neurons and glia. Identifying co-aggregating proteins within p-Tau inclusions may reveal important insights into processes affected by the aggregation of Tau. We used a proteomic approach, which combines antibody-mediated biotinylation and mass spectrometry (MS) to identify proteins proximal to p-Tau in PSP. Using this proof-of-concept workflow for identifying interacting proteins of interest, we characterized proteins proximal to p-Tau in PSP cases, identifying >84% of previously identified interaction partners of Tau and known modifiers of Tau aggregation, while 19 novel proteins not previously found associated with Tau were identified. Furthermore, our data also identified confidently assigned phosphorylation sites that have been previously reported on p-Tau. Additionally, using ingenuity pathway analysis (IPA) and human RNA-seq datasets, we identified proteins previously associated with neurological disorders and pathways involved in protein degradation, stress responses, cytoskeletal dynamics, metabolism, and neurotransmission. Together, our study demonstrates the utility of biotinylation by antibody recognition (BAR) approach to answer a fundamental question to rapidly identify proteins in proximity to p-Tau from post-mortem tissue. The application of this workflow opens up the opportunity to identify novel protein targets to give us insight into the biological process at the onset and progression of tauopathies.
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Affiliation(s)
- Rowan A. W. Radford
- Centre for Motor Neuron Disease ResearchMacquarie Medical SchoolFaculty of Medicine, Health and Human SciencesMacquarie UniversityNew South WalesNorth RydeAustralia
| | - Stephanie L. Rayner
- Centre for Motor Neuron Disease ResearchMacquarie Medical SchoolFaculty of Medicine, Health and Human SciencesMacquarie UniversityNew South WalesNorth RydeAustralia
| | - Paulina Szwaja
- Centre for Motor Neuron Disease ResearchMacquarie Medical SchoolFaculty of Medicine, Health and Human SciencesMacquarie UniversityNew South WalesNorth RydeAustralia
| | - Marco Morsch
- Centre for Motor Neuron Disease ResearchMacquarie Medical SchoolFaculty of Medicine, Health and Human SciencesMacquarie UniversityNew South WalesNorth RydeAustralia
| | - Flora Cheng
- Centre for Motor Neuron Disease ResearchMacquarie Medical SchoolFaculty of Medicine, Health and Human SciencesMacquarie UniversityNew South WalesNorth RydeAustralia
| | - Tianyi Zhu
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain InstituteThe University of QueenslandQueenslandBrisbaneAustralia
| | - Jocelyn Widagdo
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain InstituteThe University of QueenslandQueenslandBrisbaneAustralia
| | - Victor Anggono
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain InstituteThe University of QueenslandQueenslandBrisbaneAustralia
| | - Dean L. Pountney
- School of Pharmacy and Medical SciencesGriffith UniversityQueenslandGold CoastAustralia
| | - Roger Chung
- Centre for Motor Neuron Disease ResearchMacquarie Medical SchoolFaculty of Medicine, Health and Human SciencesMacquarie UniversityNew South WalesNorth RydeAustralia
| | - Albert Lee
- Centre for Motor Neuron Disease ResearchMacquarie Medical SchoolFaculty of Medicine, Health and Human SciencesMacquarie UniversityNew South WalesNorth RydeAustralia
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3
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Suhda S, Yamamoto Y, Wisesa S, Sada R, Sakisaka T. The 14-3-3γ isoform binds to and regulates the localization of endoplasmic reticulum (ER) membrane protein TMCC3 for the reticular network of the ER. J Biol Chem 2022; 299:102813. [PMID: 36549645 PMCID: PMC9860497 DOI: 10.1016/j.jbc.2022.102813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 12/07/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022] Open
Abstract
The reticular network of the endoplasmic reticulum (ER) is formed by connecting ER tubules through three-way junctions and undergoes constant remodeling through formation and loss of the three-way junctions. Transmembrane and coiled-coil domain family 3 (TMCC3), an ER membrane protein localizing at three-way junctions, has been shown to positively regulate formation of the reticular ER network. However, elements that negatively regulate TMCC3 localization have not been characterized. In this study, we report that 14-3-3γ, a phospho-serine/phospho-threonine-binding protein involved in various signal transduction pathways, is a negative regulator of TMCC3. We demonstrate that overexpression of 14-3-3γ reduced localization of TMCC3 to three-way junctions and decreased the number of three-way junctions. TMCC3 bound to 14-3-3γ through the N terminus and had deduced 14-3-3 binding motifs. Additionally, we determined that a TMCC3 mutant substituting alanine for serine to be phosphorylated in the binding motif reduced binding to 14-3-3γ. The TMCC3 mutant was more prone than wildtype TMCC3 to localize at three-way junctions in the cells overexpressing 14-3-3γ. Furthermore, the TMCC3 mutant rescued the ER sheet expansion caused by TMCC3 knockdown less than wild-type TMCC3. Taken together, these results indicate that 14-3-3γ binding negatively regulates localization of TMCC3 to the three-way junctions for the proper reticular ER network, implying that the negative regulation of TMCC3 by 14-3-3γ would underlie remodeling of the reticular network of the ER.
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Affiliation(s)
- Saihas Suhda
- Division of Membrane Dynamics, Department of Physiology and Cell Biology, Kobe University School of Medicine, Kobe, Japan
| | - Yasunori Yamamoto
- Division of Membrane Dynamics, Department of Physiology and Cell Biology, Kobe University School of Medicine, Kobe, Japan
| | - Sindhu Wisesa
- Division of Membrane Dynamics, Department of Physiology and Cell Biology, Kobe University School of Medicine, Kobe, Japan
| | - Risa Sada
- Division of Membrane Dynamics, Department of Physiology and Cell Biology, Kobe University School of Medicine, Kobe, Japan
| | - Toshiaki Sakisaka
- Division of Membrane Dynamics, Department of Physiology and Cell Biology, Kobe University School of Medicine, Kobe, Japan.
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4
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Rajendra J, Ghorai A, Dutt S. 14-3-3ζ negatively regulates mitochondrial biogenesis in GBM residual cells. Heliyon 2021; 7:e08371. [PMID: 34825085 PMCID: PMC8605068 DOI: 10.1016/j.heliyon.2021.e08371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/25/2021] [Accepted: 11/10/2021] [Indexed: 11/29/2022] Open
Abstract
Glioblastoma (GBM) is the most lethal primary brain tumour with a median survival of only 15 months. We have previously demonstrated the generation of an in vitro therapy resistance model that captures the residual resistant (RR) disease cells of GBM post-radiation. We also reported the proteomic landscape of parent, residual, and relapse cells using iTRAQ based quantitative proteomics of glioma cells. The proteomics data revealed significant up-regulation (fold change >1.5) of 14-3-3ζ, specifically in GBM RR cells. This was further confirmed by western blots in residual cells generated from GBM cell lines and patient sample-derived short-term primary culture. ShRNA-mediated knockdown of 14-3-3ζ radio-sensitized GBM cells and further stimulated therapy-induced senescence (TIS) and multinucleated giant cells (MNGCs) phenotype in RR cells. Intriguingly, 14-3-3ζ knockdown residual cells also showed a significantly higher number of mitochondria and increased mtDNA content. Indeed, in vitro GST pull-down mass spectrometry analysis of GST tagged 14-3-3ζ from RR cells identified novel interacting partners of 14-3-3ζ involved in cellular metabolism. Taken together, here we identified novel interacting partners of 14-3-3ζ and proposed an unconventional function of 14-3-3ζ as a negative regulator of TIS and mitochondrial biogenesis in residual resistant cells and loss of which also radio-sensitize GBM cells. 14-3-3ζ is up-regulated in residual disease cells of GBM. 14-3-3ζ knockdown radiosensitizes GBM cells. 14-3-3ζ knockdown increases MNGCs formation and senescence in residual cells. 14-3-3ζ negatively regulates mitochondrial biogenesis of residual disease cells. Novel interacting partners of 14-3-3ζ from residual cells are involved in cellular metabolism.
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Affiliation(s)
- Jacinth Rajendra
- Shilpee Dutt Laboratory, Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Navi Mumbai, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai, 400085, India
| | - Atanu Ghorai
- Shilpee Dutt Laboratory, Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Navi Mumbai, India
| | - Shilpee Dutt
- Shilpee Dutt Laboratory, Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Navi Mumbai, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai, 400085, India
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5
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Wang X, Liu X, An YQC, Zhang H, Meng D, Jin Y, Huo H, Yu L, Zhang J. Identification of Glutathione Peroxidase Gene Family in Ricinus communis and Functional Characterization of RcGPX4 in Cold Tolerance. FRONTIERS IN PLANT SCIENCE 2021; 12:707127. [PMID: 34804079 PMCID: PMC8602854 DOI: 10.3389/fpls.2021.707127] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 09/30/2021] [Indexed: 06/13/2023]
Abstract
Glutathione peroxidases (GPXs) protect cells against damage caused by reactive oxygen species (ROS) and play key roles in regulating many biological processes. Here, five GPXs were identified in the Ricinus communis genome. Phylogenetic analysis displayed that the GPXs were categorized into five groups. Conserved domain and gene structure analyses showed that the GPXs from different plant species harbored four highly similar motifs and conserved exon-intron arrangement patterns, indicating that their structure and function may have been conserved during evolution. Several abiotic stresses and hormone-responsive cis-acting elements existed in the promoters of the RcGPXs. The expression profiles indicated that the RcGPXs varied substantially, and some RcGPXs were coordinately regulated under abiotic stresses. Overexpression of RcGPX4 in Arabidopsis enhanced cold tolerance at seed germination but reduced freezing tolerance at seedlings. The expression of abscisic acid (ABA) signaling genes (AtABI4 and AtABI5), ABA catabolism genes (AtCYP707A1 and AtCYP707A2), gibberellin acid (GA) catabolism gene (AtGA2ox7), and cytokinin (CTK)-inducible gene (AtARR6) was regulated in the seeds of transgenic lines under cold stress. Overexpression of RcGPX4 can disturb the hydrogen peroxide (H2O2) homeostasis through the modulation of some antioxidant enzymes and compounds involved in the GSH-ascorbate cycle in transgenic plants. Additionally, RcGPX4 depended on the MAPK3-ICE1-C-repeat-binding factor (CBF)-COR signal transduction pathway and ABA-dependent pathway to negatively regulate the freezing tolerance of transgenic plants. This study provides valuable information for understanding the potential function of RcGPXs in regulating the abiotic stress responses of castor beans.
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Affiliation(s)
- Xiaoyu Wang
- College of Life Science and Food Engineering, Inner Mongolia Minzu University, Tongliao, China
- Horqin Plant Stress Biology Research Institute of Inner Mongolia Minzu University, Tongliao, China
| | - Xuming Liu
- College of Life Science and Food Engineering, Inner Mongolia Minzu University, Tongliao, China
- Horqin Plant Stress Biology Research Institute of Inner Mongolia Minzu University, Tongliao, China
| | - Yong-qiang Charles An
- U.S. Department of Agriculture-Agricultural Research Service, Plant Genetics Research Unit, Donald Danforth Plant Science Center, Saint Louis, MO, United States
| | - Hongyu Zhang
- College of Life Science and Food Engineering, Inner Mongolia Minzu University, Tongliao, China
- Horqin Plant Stress Biology Research Institute of Inner Mongolia Minzu University, Tongliao, China
| | - Di Meng
- College of Life Science and Food Engineering, Inner Mongolia Minzu University, Tongliao, China
- Horqin Plant Stress Biology Research Institute of Inner Mongolia Minzu University, Tongliao, China
| | - Yanan Jin
- College of Life Science and Food Engineering, Inner Mongolia Minzu University, Tongliao, China
- Horqin Plant Stress Biology Research Institute of Inner Mongolia Minzu University, Tongliao, China
| | - Hongyan Huo
- College of Life Science and Food Engineering, Inner Mongolia Minzu University, Tongliao, China
- Horqin Plant Stress Biology Research Institute of Inner Mongolia Minzu University, Tongliao, China
| | - Lili Yu
- College of Life Science and Food Engineering, Inner Mongolia Minzu University, Tongliao, China
| | - Jixing Zhang
- College of Life Science and Food Engineering, Inner Mongolia Minzu University, Tongliao, China
- Horqin Plant Stress Biology Research Institute of Inner Mongolia Minzu University, Tongliao, China
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6
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Xu F, Tautenhahn HM, Dirsch O, Dahmen U. Modulation of Autophagy: A Novel "Rejuvenation" Strategy for the Aging Liver. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:6611126. [PMID: 33628363 PMCID: PMC7889356 DOI: 10.1155/2021/6611126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/08/2020] [Accepted: 01/23/2021] [Indexed: 12/11/2022]
Abstract
Aging is a natural life process which leads to a gradual decline of essential physiological processes. For the liver, it leads to alterations in histomorphology (steatosis and fibrosis) and function (protein synthesis and energy generation) and affects central hepatocellular processes (autophagy, mitochondrial respiration, and hepatocyte proliferation). These alterations do not only impair the metabolic capacity of the liver but also represent important factors in the pathogenesis of malignant liver disease. Autophagy is a recycling process for eukaryotic cells to degrade dysfunctional intracellular components and to reuse the basic substances. It plays a crucial role in maintaining cell homeostasis and in resisting environmental stress. Emerging evidence shows that modulating autophagy seems to be effective in improving the age-related alterations of the liver. However, autophagy is a double-edged sword for the aged liver. Upregulating autophagy alleviates hepatic steatosis and ROS-induced cellular stress and promotes hepatocyte proliferation but may aggravate hepatic fibrosis. Therefore, a well-balanced autophagy modulation strategy might be suitable to alleviate age-related liver dysfunction. Conclusion. Modulation of autophagy is a promising strategy for "rejuvenation" of the aged liver. Detailed knowledge regarding the most devastating processes in the individual patient is needed to effectively counteract aging of the liver without causing obvious harm.
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Affiliation(s)
- Fengming Xu
- Department of General, Visceral and Vascular Surgery, Jena University Hospital, Jena 07747, Germany
| | - Hans-Michael Tautenhahn
- Department of General, Visceral and Vascular Surgery, Jena University Hospital, Jena 07747, Germany
| | - Olaf Dirsch
- Institute of Pathology, Klinikum Chemnitz gGmbH, Chemnitz 09111, Germany
| | - Uta Dahmen
- Department of General, Visceral and Vascular Surgery, Jena University Hospital, Jena 07747, Germany
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7
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Natarajan N, Thiruvenkatam V. An Insight of Scientific Developments in TSC for Better Therapeutic Strategy. Curr Top Med Chem 2020; 20:2080-2093. [PMID: 32842942 DOI: 10.2174/1568026620666200825170355] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/15/2020] [Accepted: 07/20/2020] [Indexed: 11/22/2022]
Abstract
Tuberous sclerosis complex (TSC) is a rare genetic disease, which is characterized by noncancerous tumors in multi-organ systems in the body. Mutations in the TSC1 or TSC2 genes are known to cause the disease. The resultant mutant proteins TSC1 (hamartin) and TSC2 (tuberin) complex evade its normal tumor suppressor function, which leads to abnormal cell growth and proliferation. Both TSC1 and TSC2 are involved in several protein-protein interactions, which play a significant role in maintaining cellular homeostasis. The recent biochemical, genetic, structural biology, clinical and drug discovery advancements on TSC give a useful insight into the disease as well as the molecular aspects of TSC1 and TSC2. The complex nature of TSC disease, a wide range of manifestations, mosaicism and several other factors limits the treatment choices. This review is a compilation of the course of TSC, starting from its discovery to the current findings that would take us a step ahead in finding a cure for TSC.
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Affiliation(s)
- Nalini Natarajan
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gujarat-382355, India
| | - Vijay Thiruvenkatam
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gujarat-382355, India
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8
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Abstract
A complex molecular machinery converges on the surface of lysosomes to ensure that the growth-promoting signaling mediated by mechanistic target of rapamycin complex 1 (mTORC1) is tightly controlled by the availability of nutrients and growth factors. The final step in this activation process is dependent on Rheb, a small GTPase that binds to mTOR and allosterically activates its kinase activity. Here we review the mechanisms that determine the subcellular localization of Rheb (and the closely related RhebL1 protein) as well as the significance of these mechanisms for controlling mTORC1 activation. In particular, we explore how the relatively weak membrane interactions conferred by C-terminal farnesylation are critical for the ability of Rheb to activate mTORC1. In addition to supporting transient membrane interactions, Rheb C-terminal farnesylation also supports an interaction between Rheb and the δ subunit of phosphodiesterase 6 (PDEδ). This interaction provides a potential mechanism for targeting Rheb to membranes that contain Arl2, a small GTPase that triggers the release of prenylated proteins from PDEδ. The minimal membrane targeting conferred by C-terminal farnesylation of Rheb and RhebL1 distinguishes them from other members of the Ras superfamily that possess additional membrane interaction motifs that work with farnesylation for enrichment on the specific subcellular membranes where they engage key effectors. Finally, we highlight diversity in Rheb membrane targeting mechanisms as well as the potential for alternative mTORC1 activation mechanisms across species.
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Affiliation(s)
- Brittany Angarola
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Shawn M Ferguson
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, 06510, USA
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9
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Xu F, Hua C, Tautenhahn HM, Dirsch O, Dahmen U. The Role of Autophagy for the Regeneration of the Aging Liver. Int J Mol Sci 2020; 21:ijms21103606. [PMID: 32443776 PMCID: PMC7279469 DOI: 10.3390/ijms21103606] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/15/2020] [Accepted: 05/18/2020] [Indexed: 02/07/2023] Open
Abstract
Age is one of the key risk factors to develop malignant diseases leading to a high incidence of hepatic tumors in the elderly population. The only curative treatment for hepatic tumors is surgical removal, which initiates liver regeneration. However, liver regeneration is impaired with aging, leading to an increased surgical risk for the elderly patient. Due to the increased risk, those patients are potentially excluded from curative surgery. Aging impairs autophagy via lipofuscin accumulation and inhibition of autophagosome formation. Autophagy is a recycling mechanism for eukaryotic cells to maintain homeostasis. Its principal function is to degrade endogenous bio-macromolecules for recycling cellular substances. A number of recent studies have shown that the reduced regenerative capacity of the aged remnant liver can be restored by promoting autophagy. Autophagy can be activated via multiple mTOR-dependent and mTOR-independent pathways. However, inducing autophagy through the mTOR-dependent pathway alone severely impairs liver regeneration. In contrast, recent observations suggest that inducing autophagy via mTOR-independent pathways might be promising in promoting liver regeneration. Conclusion: Activation of autophagy via an mTOR-independent autophagy inducer is a potential therapy for promoting liver regeneration, especially in the elderly patients at risk.
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Affiliation(s)
- Fengming Xu
- Department of General, Visceral and Vascular Surgery, Jena University Hospital, 07747 Jena, Germany; (F.X.); (C.H.); (H.-M.T.)
| | - Chuanfeng Hua
- Department of General, Visceral and Vascular Surgery, Jena University Hospital, 07747 Jena, Germany; (F.X.); (C.H.); (H.-M.T.)
| | - Hans-Michael Tautenhahn
- Department of General, Visceral and Vascular Surgery, Jena University Hospital, 07747 Jena, Germany; (F.X.); (C.H.); (H.-M.T.)
| | - Olaf Dirsch
- Institute of Pathology, Klinikum Chemnitz gGmbH, 09111 Chemnitz, Germany;
| | - Uta Dahmen
- Department of General, Visceral and Vascular Surgery, Jena University Hospital, 07747 Jena, Germany; (F.X.); (C.H.); (H.-M.T.)
- Correspondence: ; Tel.: +49-03641-9325350
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10
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Pennington KL, Chan TY, Torres MP, Andersen JL. The dynamic and stress-adaptive signaling hub of 14-3-3: emerging mechanisms of regulation and context-dependent protein-protein interactions. Oncogene 2018; 37:5587-5604. [PMID: 29915393 PMCID: PMC6193947 DOI: 10.1038/s41388-018-0348-3] [Citation(s) in RCA: 224] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 05/07/2018] [Accepted: 05/07/2018] [Indexed: 12/14/2022]
Abstract
14-3-3 proteins are a family of structurally similar phospho-binding proteins that regulate essentially every major cellular function. Decades of research on 14-3-3s have revealed a remarkable network of interacting proteins that demonstrate how 14-3-3s integrate and control multiple signaling pathways. In particular, these interactions place 14-3-3 at the center of the signaling hub that governs critical processes in cancer, including apoptosis, cell cycle progression, autophagy, glucose metabolism, and cell motility. Historically, the majority of 14-3-3 interactions have been identified and studied under nutrient-replete cell culture conditions, which has revealed important nutrient driven interactions. However, this underestimates the reach of 14-3-3s. Indeed, the loss of nutrients, growth factors, or changes in other environmental conditions (e.g., genotoxic stress) will not only lead to the loss of homeostatic 14-3-3 interactions, but also trigger new interactions, many of which are likely stress adaptive. This dynamic nature of the 14-3-3 interactome is beginning to come into focus as advancements in mass spectrometry are helping to probe deeper and identify context-dependent 14-3-3 interactions-providing a window into adaptive phosphorylation-driven cellular mechanisms that orchestrate the tumor cell's response to a variety of environmental conditions including hypoxia and chemotherapy. In this review, we discuss emerging 14-3-3 regulatory mechanisms with a focus on post-translational regulation of 14-3-3 and dynamic protein-protein interactions that illustrate 14-3-3's role as a stress-adaptive signaling hub in cancer.
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Affiliation(s)
- K L Pennington
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - T Y Chan
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - M P Torres
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - J L Andersen
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA.
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11
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Zhang L, Wang H. Autophagy in Traumatic Brain Injury: A New Target for Therapeutic Intervention. Front Mol Neurosci 2018; 11:190. [PMID: 29922127 PMCID: PMC5996030 DOI: 10.3389/fnmol.2018.00190] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Accepted: 05/15/2018] [Indexed: 11/23/2022] Open
Abstract
Traumatic brain injury (TBI) is one of the most devastating forms of brain injury. Many pathological mechanisms such as oxidative stress, apoptosis and inflammation all contribute to the secondary brain damage and poor outcomes of TBI. Current therapies are often ineffective and poorly tolerated, which drive the explore of new therapeutic targets for TBI. Autophagy is a highly conserved intracellular mechanism during evolution. It plays an important role in elimination abnormal intracellular proteins or organelles to maintain cell stability. Besides, autophagy has been researched in various models including TBI. Previous studies have deciphered that regulation of autophagy by different molecules and pathways could exhibit anti-oxidative stress, anti-apoptosis and anti-inflammation effects in TBI. Hence, autophagy is a promising target for further therapeutic development in TBI. The present review provides an overview of current knowledge about the mechanism of autophagy, the frequently used methods to monitor autophagy, the functions of autophagy in TBI as well as its potential molecular mechanisms based on the pharmacological regulation of autophagy.
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Affiliation(s)
- Li Zhang
- Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, China
| | - Handong Wang
- Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, China
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12
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Kane MS, Paris A, Codron P, Cassereau J, Procaccio V, Lenaers G, Reynier P, Chevrollier A. Current mechanistic insights into the CCCP-induced cell survival response. Biochem Pharmacol 2017; 148:100-110. [PMID: 29277693 DOI: 10.1016/j.bcp.2017.12.018] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 12/20/2017] [Indexed: 01/13/2023]
Abstract
The ring-substituted derivatives of carbonyl cyanide phenylhydrazone, CCCP and FCCP, are routinely used for the analysis of the mitochondrial function in living cells, tissues, and isolated mitochondrial preparations. CCCP and FCCP are now being increasingly used for investigating the mechanisms of autophagy by inducing mitochondrial degradation through the disruption of the mitochondrial membrane potential (ΔΨm). Sustained perturbation of ΔΨm, which is normally tightly controlled to ensure cell proliferation and survival, triggers various stress pathways as part of the cellular adaptive response, the main components of which are mitophagy and autophagy. We here review current mechanistic insights into the induction of mitophagy and autophagy by CCCP and FCCP. In particular, we analyze the cellular modifications produced by the activation of two major pathways involving the signaling of the nuclear factor erythroid 2-related factor 2 (Nrf2) and the transcription factor EB (TFEB), and discuss the contribution of these pathways to the integrated cellular stress response.
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Affiliation(s)
- Mariame Selma Kane
- MitoLab, Mitochondrial Medicine Research Centre, UMR CNRS 6015-INSERM 1083, Institut MitoVasc, University of Angers, 49933 Angers, France
| | - Aurelien Paris
- MitoLab, Mitochondrial Medicine Research Centre, UMR CNRS 6015-INSERM 1083, Institut MitoVasc, University of Angers, 49933 Angers, France
| | - Philippe Codron
- MitoLab, Mitochondrial Medicine Research Centre, UMR CNRS 6015-INSERM 1083, Institut MitoVasc, University of Angers, 49933 Angers, France
| | - Julien Cassereau
- MitoLab, Mitochondrial Medicine Research Centre, UMR CNRS 6015-INSERM 1083, Institut MitoVasc, University of Angers, 49933 Angers, France
| | - Vincent Procaccio
- MitoLab, Mitochondrial Medicine Research Centre, UMR CNRS 6015-INSERM 1083, Institut MitoVasc, University of Angers, 49933 Angers, France
| | - Guy Lenaers
- MitoLab, Mitochondrial Medicine Research Centre, UMR CNRS 6015-INSERM 1083, Institut MitoVasc, University of Angers, 49933 Angers, France
| | - Pascal Reynier
- MitoLab, Mitochondrial Medicine Research Centre, UMR CNRS 6015-INSERM 1083, Institut MitoVasc, University of Angers, 49933 Angers, France
| | - Arnaud Chevrollier
- MitoLab, Mitochondrial Medicine Research Centre, UMR CNRS 6015-INSERM 1083, Institut MitoVasc, University of Angers, 49933 Angers, France.
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13
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Ikhlas S, Ahmad M. Metformin: Insights into its anticancer potential with special reference to AMPK dependent and independent pathways. Life Sci 2017; 185:53-62. [DOI: 10.1016/j.lfs.2017.07.029] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 07/15/2017] [Accepted: 07/26/2017] [Indexed: 12/19/2022]
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14
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Down-regulation of adenylate kinase 5 in temporal lobe epilepsy patients and rat model. J Neurol Sci 2016; 366:20-26. [DOI: 10.1016/j.jns.2016.04.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/01/2016] [Accepted: 04/19/2016] [Indexed: 11/19/2022]
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15
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Heras-Sandoval D, Pérez-Rojas JM, Hernández-Damián J, Pedraza-Chaverri J. The role of PI3K/AKT/mTOR pathway in the modulation of autophagy and the clearance of protein aggregates in neurodegeneration. Cell Signal 2014; 26:2694-701. [DOI: 10.1016/j.cellsig.2014.08.019] [Citation(s) in RCA: 646] [Impact Index Per Article: 64.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 08/18/2014] [Indexed: 12/13/2022]
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16
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Takei N, Nawa H. mTOR signaling and its roles in normal and abnormal brain development. Front Mol Neurosci 2014; 7:28. [PMID: 24795562 PMCID: PMC4005960 DOI: 10.3389/fnmol.2014.00028] [Citation(s) in RCA: 218] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 03/30/2014] [Indexed: 11/15/2022] Open
Abstract
Target of rapamycin (TOR) was first identified in yeast as a target molecule of rapamycin, an anti-fugal and immunosuppressant macrolide compound. In mammals, its orthologue is called mammalian TOR (mTOR). mTOR is a serine/threonine kinase that converges different extracellular stimuli, such as nutrients and growth factors, and diverges into several biochemical reactions, including translation, autophagy, transcription, and lipid synthesis among others. These biochemical reactions govern cell growth and cause cells to attain an anabolic state. Thus, the disruption of mTOR signaling is implicated in a wide array of diseases such as cancer, diabetes, and obesity. In the central nervous system, the mTOR signaling cascade is activated by nutrients, neurotrophic factors, and neurotransmitters that enhances protein (and possibly lipid) synthesis and suppresses autophagy. These processes contribute to normal neuronal growth by promoting their differentiation, neurite elongation and branching, and synaptic formation during development. Therefore, disruption of mTOR signaling may cause neuronal degeneration and abnormal neural development. While reduced mTOR signaling is associated with neurodegeneration, excess activation of mTOR signaling causes abnormal development of neurons and glia, leading to brain malformation. In this review, we first introduce the current state of molecular knowledge of mTOR complexes and signaling in general. We then describe mTOR activation in neurons, which leads to translational enhancement, and finally discuss the link between mTOR and normal/abnormal neuronal growth during development.
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Affiliation(s)
- Nobuyuki Takei
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University Niigata, Japan
| | - Hiroyuki Nawa
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University Niigata, Japan
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17
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Min S, Liang X, Zhang M, Zhang Y, Mei S, Liu J, Liu J, Su X, Cao S, Zhong X, Li Y, Sun J, Liu Q, Jiang X, Che Y, Yang R. Multiple Tumor-Associated MicroRNAs Modulate the Survival and Longevity of Dendritic Cells by Targeting YWHAZ and Bcl2 Signaling Pathways. THE JOURNAL OF IMMUNOLOGY 2013; 190:2437-46. [DOI: 10.4049/jimmunol.1202282] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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18
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Brennan GP, Jimenez-Mateos EM, McKiernan RC, Engel T, Tzivion G, Henshall DC. Transgenic overexpression of 14-3-3 zeta protects hippocampus against endoplasmic reticulum stress and status epilepticus in vivo. PLoS One 2013; 8:e54491. [PMID: 23359526 PMCID: PMC3554740 DOI: 10.1371/journal.pone.0054491] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 12/12/2012] [Indexed: 01/05/2023] Open
Abstract
14-3-3 proteins are ubiquitous molecular chaperones that are abundantly expressed in the brain where they regulate cell functions including metabolism, the cell cycle and apoptosis. Brain levels of several 14-3-3 isoforms are altered in diseases of the nervous system, including epilepsy. The 14-3-3 zeta (ζ) isoform has been linked to endoplasmic reticulum (ER) function in neurons, with reduced levels provoking ER stress and increasing vulnerability to excitotoxic injury. Here we report that transgenic overexpression of 14-3-3ζ in mice results in selective changes to the unfolded protein response pathway in the hippocampus, including down-regulation of glucose-regulated proteins 78 and 94, activating transcription factors 4 and 6, and Xbp1 splicing. No differences were found between wild-type mice and transgenic mice for levels of other 14-3-3 isoforms or various other 14-3-3 binding proteins. 14-3-3ζ overexpressing mice were potently protected against cell death caused by intracerebroventricular injection of the ER stressor tunicamycin. 14-3-3ζ overexpressing mice were also potently protected against neuronal death caused by prolonged seizures. These studies demonstrate that increased 14-3-3ζ levels protect against ER stress and seizure-damage despite down-regulation of the unfolded protein response. Delivery of 14-3-3ζ may protect against pathologic changes resulting from prolonged or repeated seizures or where injuries provoke ER stress.
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Affiliation(s)
- Gary P. Brennan
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Eva M. Jimenez-Mateos
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Ross C. McKiernan
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Tobias Engel
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Guri Tzivion
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - David C. Henshall
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
- * E-mail:
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Hoogeveen-Westerveld M, van Unen L, van den Ouweland A, Halley D, Hoogeveen A, Nellist M. The TSC1-TSC2 complex consists of multiple TSC1 and TSC2 subunits. BMC BIOCHEMISTRY 2012; 13:18. [PMID: 23006675 PMCID: PMC3517901 DOI: 10.1186/1471-2091-13-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 09/21/2012] [Indexed: 01/05/2023]
Abstract
Background Mutations to the TSC1 and TSC2 genes cause the disease tuberous sclerosis complex. The TSC1 and TSC2 gene products form a protein complex that integrates multiple metabolic signals to regulate the activity of the target of rapamycin (TOR) complex 1 (TORC1) and thereby control cell growth. Here we investigate the quaternary structure of the TSC1-TSC2 complex by gel filtration and coimmunoprecipitation. Results TSC1 and TSC2 co-eluted in high molecular weight fractions by gel filtration. Coimmunoprecipitation of distinct tagged TSC1 and TSC2 isoforms demonstrated that TSC1-TSC2 complexes contain multiple TSC1 and TSC2 subunits. Conclusions TSC1 and TSC2 interact to form large complexes containing multiple TSC1 and TSC2 subunits.
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20
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Wang H, Zhang Q, Wen Q, Zheng Y, Lazarovici P, Philip L, Jiang H, Lin J, Zheng W. Proline-rich Akt substrate of 40kDa (PRAS40): a novel downstream target of PI3k/Akt signaling pathway. Cell Signal 2011; 24:17-24. [PMID: 21906675 DOI: 10.1016/j.cellsig.2011.08.010] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 08/19/2011] [Accepted: 08/20/2011] [Indexed: 01/09/2023]
Abstract
Modifications in signaling of the proline-rich Akt substrate of 40-kDa (PRAS40) pathway is implicated in type 2 diabetes and melanoma. PRAS40 is known for its ability to regulate the mammalian target of rapamycin complex 1 (mTORC1) kinase activity, possessing a key regulatory role at the cross point of signal transduction pathways activated by growth factor receptors. Recently it has been found that PRAS40 is regulated by its upstream phosphatidylinositol 3-kinase/Akt (PI3K/Akt) which is activated by many tyrosine kinase receptors growth factors including insulin-like growth factor 1. Also, PRAS40 functions downstream of mTORC1 and upstream from its effectors ribosomal protein S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E binding protein 1 (4E-BP1). Phosphorylation of PRAS40 by Akt and mTORC1 disrupts the binding between mTORC1 and PRAS40, and relieves the inhibitory constraint of PRAS40 on mTORC1 activity. This review summarizes the signaling regulating PRAS40 phosphorylation, as well as the dual function of PRAS40 as substrate and inhibitor of mTORC1 upon growth factor stimulation and under pathophysiological conditions.
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Affiliation(s)
- Haitao Wang
- Neuropharmacology, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China
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21
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Neal CL, Yu D. 14-3-3ζ as a prognostic marker and therapeutic target for cancer. Expert Opin Ther Targets 2011; 14:1343-54. [PMID: 21058923 DOI: 10.1517/14728222.2010.531011] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
IMPORTANCE OF THE FIELD The ubiquitously expressed 14-3-3ζ protein is involved in numerous important cellular pathways involved in cancer. Recent research suggests 14-3-3ζ may play a central role regulating multiple pathways responsible for cancer initiation and progression. This review will provide an overview of 14-3-3 proteins and address the role of 14-3-3ζ overexpression in cancer. AREAS COVERED IN THIS REVIEW The review covers the basic role of 14-3-3 in regulation of multiple pathways with a focus on 14-3-3ζ as a clinically relevant biomarker for cancer recurrence. WHAT THE READER WILL GAIN 14-3-3ζ overexpression has been found in multiple cancers; however, the clinical implications were unclear. Recently, 14-3-3ζ has been identified as a biomarker for poor prognosis and chemoresistance in multiple tumor types, indicating a potential clinical application for using 14-3-3ζ in selecting treatment options and predicting cancer patients' outcome. TAKE HOME MESSAGE 14-3-3ζ is a potential prognostic marker of cancer recurrence and predictive marker for therapeutic resistance. The overexpression of 14-3-3ζ in multiple cancers suggests that it may be a common target to intervene tumor progression; therefore, more efforts are needed for the development of 14-3-3 inhibitors.
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Affiliation(s)
- Christopher L Neal
- The University of Texas M. D. Anderson Cancer Center, Department of Molecular and Cellular Oncology, Houston, TX 77030, USA
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22
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Functional phosphoproteomic analysis reveals cold-shock domain protein A to be a Bcr-Abl effector-regulating proliferation and transformation in chronic myeloid leukemia. Cell Death Dis 2010; 1:e93. [PMID: 21368869 PMCID: PMC3032323 DOI: 10.1038/cddis.2010.72] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
One proposed strategy to suppress the proliferation of imatinib-resistant cells in chronic myeloid leukemia (CML) is to inhibit key proteins downstream of Bcr-Abl. The PI3K/Akt pathway is activated by Bcr-Abl and is specifically required for the growth of CML cells. To identify targets of this pathway, we undertook a proteomic screen and identified several proteins that differentially bind 14-3-3, dependent on Bcr-Abl kinase activity. An siRNA screen of candidates selected by bioinformatics analysis reveals cold-shock domain protein A (CSDA), shown previously to regulate cell cycle progression in epithelial cells, to be a positive regulator of proliferation in a CML cell line. We show that Akt can phosphorylate the serine 134 residue of CSDA but, downstream of Bcr-Abl activity, this modification is mediated through the activation of MEK/p90 ribosomal S6 kinase (RSK) signaling. Inhibition of RSK, similarly to treatment with imatinib, blocked proliferation specifically in Bcr-Abl-positive leukemia cell lines, as well as cells from CML patients. Furthermore, these primary CML cells showed an increase in CSDA phosphorylation. Expression of a CSDA phospho-deficient mutant resulted in the decrease of Bcr-Abl-dependent transformation in Rat1 cells. Our results support a model whereby phosphorylation of CSDA downstream of Bcr-Abl enhances proliferation in CML cells to drive leukemogenesis.
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23
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Miyazaki M, McCarthy JJ, Esser KA. Insulin like growth factor-1-induced phosphorylation and altered distribution of tuberous sclerosis complex (TSC)1/TSC2 in C2C12 myotubes. FEBS J 2010; 277:2180-91. [PMID: 20412061 DOI: 10.1111/j.1742-4658.2010.07635.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Insulin like growth factor-1 (IGF-1) is established as an anabolic factor that can induce skeletal muscle growth by activating the phosphoinositide 3-kinase/Akt/mammalian target of rapamycin (mTOR) pathway. Although this signaling pathway has been the subject of much study, the molecular mechanisms linking IGF-1 binding to mTOR activation remain poorly defined in muscle. The present study aimed to test the hypothesis that IGF-1 activation of mTOR in C2C12 myotubes requires a phosphorylation-dependent, altered distribution of the tuberous sclerosis complex (TSC)1/TSC2 complex from the membrane to the cytosol. We found that IGF-1 treatment does not affect complex formation between TSC1 and TSC2, but rather IGF-1 induces an altered distribution of the TSC1/TSC2 complex in C2C12 myotubes. In response to IGF-1 treatment, there was a relative redistribution of the TSC1/TSC2 complex, composed of TSC1 and phosphorylated TSC2, from the membrane to the cytosol. IGF-1-stimulated TSC1/TSC2 phosphorylation and redistribution were completely prevented by the phosphoinositide 3-kinase inhibitor wortmannin, but were not with the downstream mTOR inhibitor, rapamycin. When a nonphosphorylatable form of TSC2 (S939A) was overexpressed, phosphorylation-dependent binding of the scaffold protein 14-3-3 to TSC2 was diminished and no redistribution of the TSC1/TSC2 complex was observed after IGF-1 stimulation. These results indicate that TSC2 phosphorylation in response to IGF-1 treatment is necessary for the altered distribution of the TSC1/TSC2 complex to the cytosol. We suggest that this translocation is likely critical for mTOR activation by dissociating the interaction between the GTPase activating protein activity of the TSC1/TSC2 complex and its downstream target, Ras homolog enriched in brain.
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Affiliation(s)
- Mitsunori Miyazaki
- Center for Muscle Biology, Department of Physiology, University of Kentucky, Lexington, USA
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24
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The TSC1–TSC2 Complex. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/s1874-6047(10)28002-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
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25
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Miyazaki M, Esser KA. REDD2 is enriched in skeletal muscle and inhibits mTOR signaling in response to leucine and stretch. Am J Physiol Cell Physiol 2009; 296:C583-92. [PMID: 19129461 DOI: 10.1152/ajpcell.00464.2008] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The protein kinase mammalian target of rapamycin (mTOR) is well established as a key regulator of skeletal muscle size. In this study, we determined that the stress responsive gene REDD2 (regulated in development and DNA damage responses 2) is a negative regulator of mTOR signaling and is expressed predominantly in skeletal muscle. Overexpression of REDD2 in muscle cells significantly inhibited basal mTOR signaling and diminished the response of mTOR to leucine addition or mechanical stretch. The inhibitory function of REDD2 on mTOR signaling seems to be mediated downstream or independent of Akt signaling and upstream of Rheb (Ras homolog enriched in brain). Knock down of tuberous sclerosis complex 2 (TSC2) using small interfering (si)RNA potently activated mTOR signaling and was sufficient to rescue REDD2 inhibition of mTOR activity, suggesting that REDD2 functions by modulating TSC2 function. Immunoprecipitation assays demonstrated that REDD2 does not directly interact with either TSC1 or TSC2. However, we found that REDD2 forms a complex with 14-3-3 protein and that increasing expression of REDD2 acts to competitively dissociate TSC2 from 14-3-3 and inhibits mTOR signaling. These findings demonstrate that REDD2 is a skeletal muscle specific inhibitory modulator of mTOR signaling and identify TSC2 and 14-3-3 as key molecular links between REDD2 and mTOR function.
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Affiliation(s)
- Mitsunori Miyazaki
- Dept. of Physiology, College of Medicine, Univ. of Kentucky, 800 Rose St., UKMC MS508, Lexington, KY 40536, USA
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26
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Morrison DK. The 14-3-3 proteins: integrators of diverse signaling cues that impact cell fate and cancer development. Trends Cell Biol 2008; 19:16-23. [PMID: 19027299 DOI: 10.1016/j.tcb.2008.10.003] [Citation(s) in RCA: 479] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Revised: 10/28/2008] [Accepted: 10/29/2008] [Indexed: 10/21/2022]
Abstract
The highly conserved 14-3-3 protein family has risen to a position of importance in cell biology owing to its involvement in vital cellular processes, such as metabolism, protein trafficking, signal transduction, apoptosis and cell-cycle regulation. The 14-3-3 proteins are phospho-serine/phospho-threonine binding proteins that interact with a diverse array of binding partners. Because many 14-3-3 interactions are phosphorylation-dependent, 14-3-3 has been tightly integrated into the core phospho-regulatory pathways that are crucial for normal growth and development and that often become dysregulated in human disease states such as cancer. This review examines the recent advances that further elucidate the role of 14-3-3 proteins as integrators of diverse signaling cues that influence cell fate decisions and tumorigenesis.
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Affiliation(s)
- Deborah K Morrison
- Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, Frederick MD 21702, USA.
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Abstract
TSC1 and TSC2 are the tumour-suppressor genes mutated in the tumour syndrome TSC (tuberous sclerosis complex). Their gene products form a complex that has become the focus of many signal transduction researchers. The TSC1-TSC2 (hamartin-tuberin) complex, through its GAP (GTPase-activating protein) activity towards the small G-protein Rheb (Ras homologue enriched in brain), is a critical negative regulator of mTORC1 (mammalian target of rapamycin complex 1). As mTORC1 activity controls anabolic processes to promote cell growth, it is exquisitely sensitive to alterations in cell growth conditions. Through numerous phosphorylation events, the TSC1-TSC2 complex has emerged as the sensor and integrator of these growth conditions, relaying signals from diverse cellular pathways to properly modulate mTORC1 activity. In the present review we focus on the molecular details of TSC1-TSC2 complex regulation and function as it relates to the control of Rheb and mTORC1.
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28
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DeYoung MP, Horak P, Sofer A, Sgroi D, Ellisen LW. Hypoxia regulates TSC1/2-mTOR signaling and tumor suppression through REDD1-mediated 14-3-3 shuttling. Genes Dev 2008; 22:239-51. [PMID: 18198340 DOI: 10.1101/gad.1617608] [Citation(s) in RCA: 533] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hypoxia induces rapid and dramatic changes in cellular metabolism, in part through inhibition of target of rapamycin (TOR) kinase complex 1 (TORC1) activity. Genetic studies have shown the tuberous sclerosis tumor suppressors TSC1/2 and the REDD1 protein to be essential for hypoxia regulation of TORC1 activity in Drosophila and in mammalian cells. The molecular mechanism and physiologic significance of this effect of hypoxia remain unknown. Here, we demonstrate that hypoxia and REDD1 suppress mammalian TORC1 (mTORC1) activity by releasing TSC2 from its growth factor-induced association with inhibitory 14-3-3 proteins. Endogenous REDD1 is required for both dissociation of endogenous TSC2/14-3-3 and inhibition of mTORC1 in response to hypoxia. REDD1 mutants that fail to bind 14-3-3 are defective in eliciting TSC2/14-3-3 dissociation and mTORC1 inhibition, while TSC2 mutants that do not bind 14-3-3 are inactive in hypoxia signaling to mTORC1. In vitro, loss of REDD1 signaling promotes proliferation and anchorage-independent growth under hypoxia through mTORC1 dysregulation. In vivo, REDD1 loss elicits tumorigenesis in a mouse model, and down-regulation of REDD1 is observed in a subset of human cancers. Together, these findings define a molecular mechanism of signal integration by TSC1/2 that provides insight into the ability of REDD1 to function in a hypoxia-dependent tumor suppressor pathway.
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Affiliation(s)
- Maurice Phillip DeYoung
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, MA 02114, USA
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29
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The tuberous sclerosis gene products hamartin and tuberin are multifunctional proteins with a wide spectrum of interacting partners. Mutat Res 2008; 658:234-46. [PMID: 18291711 DOI: 10.1016/j.mrrev.2008.01.001] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Revised: 12/21/2007] [Accepted: 01/03/2008] [Indexed: 12/26/2022]
Abstract
Mutations in the tumor suppressor genes TSC1 and TSC2, encoding hamartin and tuberin, respectively, cause the tumor syndrome tuberous sclerosis with similar phenotypes. Until now, over 50 proteins have been demonstrated to interact with hamartin and/or tuberin. Besides tuberin, the proteins DOCK7, ezrin/radixin/moesin, FIP200, IKKbeta, Melted, Merlin, NADE(p75NTR), NF-L, Plk1 and TBC7 have been found to interact with hamartin. Whereas Plk1 and TBC7 have been demonstrated not to bind to tuberin, for all the other hamartin-interacting proteins the question, whether they can also bind to tuberin, has not been studied. Tuberin interacts with 14-3-3 beta,epsilon,gamma,eta,sigma,tau,zeta, Akt, AMPK, CaM, CRB3/PATJ, cyclin A, cyclins D1, D2, D3, Dsh, ERalpha, Erk, FoxO1, HERC1, HPV16 E6, HSCP-70, HSP70-1, MK2, NEK1, p27KIP1, Pam, PC1, PP2Ac, Rabaptin-5, Rheb, RxRalpha/VDR and SMAD2/3. 14-3-3 beta,epsilon,gamma,eta,sigma,tau,zeta, Akt, Dsh, FoxO1, HERC1, p27KIP1 and PP2Ac are known not to bind to hamartin. For the other tuberin-interacting proteins this question remains elusive. The proteins axin, Cdk1, cyclin B1, GADD34, GSK3, mTOR and RSK1 have been found to co-immunoprecipitate with both, hamartin and tuberin. The kinases Cdk1 and IKKbeta phosphorylate hamartin, Erk, Akt, MK2, AMPK and RSK1 phosphorylate tuberin, and GSK3 phosphorylates both, hamartin and tuberin. This detailed summary of protein interactions allows new insights into their relevance for the wide variety of different functions of hamartin and tuberin.
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Rosner M, Freilinger A, Hanneder M, Fujita N, Lubec G, Tsuruo T, Hengstschläger M. p27
Kip1
localization depends on the tumor suppressor protein tuberin. Hum Mol Genet 2007; 16:1541-56. [PMID: 17470459 DOI: 10.1093/hmg/ddm103] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
p27(Kip1) plays an important role in cell cycle regulation by inhibiting cyclin-CDK complex activity in the nucleus. p27(Kip1) is regulated by its concentration as well as by its subcellular localization. Tuberin, encoded by the tuberous sclerosis tumor suppressor gene TSC2, is a potent negative cell cycle regulator. We show herein, that tuberin induces nuclear p27 localization by inhibiting its 14-3-3-mediated cytoplasmic retention. Tuberin interferes with 14-3-3's counteracting effects on p27-mediated cell cycle arrest. Akt-mediated phosphorylation of p27, but not of tuberin, negatively regulates tuberin's potential to trigger p27 nuclear localization. In G0 cells, tuberin binds p27 triggering downregulation of p27's binding to 14-3-3 and of its cytoplasmic retention. At transition to S phase p27 is phosphorylated by Akt, tuberin/p27 complex levels are downregulated and binding of p27 to 14-3-3 increases triggering cytoplasmic retention of p27. These findings demonstrate p27 localization during the mammalian cell cycle to be under the control of the tumor suppressor tuberin.
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Affiliation(s)
- Margit Rosner
- Medical Genetics, Obstetrics and Gynecology, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
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31
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Nobukuni T, Kozma SC, Thomas G. hvps34, an ancient player, enters a growing game: mTOR Complex1/S6K1 signaling. Curr Opin Cell Biol 2007; 19:135-41. [PMID: 17321123 DOI: 10.1016/j.ceb.2007.02.019] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Accepted: 02/12/2007] [Indexed: 10/23/2022]
Abstract
Recent studies have shown that the nutrient input to the mTOR Complex1/S6K1 signaling pathway is mediated by class 3 PI3K or hVps34, the oldest member of the PI3K family. Moreover, studies to date would suggest that during the evolution of multicellular organisms this ancient branch of the pathway was merged with the growth-factor-hormone-controlled class 1 PI3K pathway at the level of mTOR Complex1 to control the development and growth of the organism. However, hVps34 also plays a role in the regulation of macroautophagy - the mechanism by which cells generate nutrients, such as amino acids, through the degradation of intracellular complexes, including mitochondria and ribosomes. These functions of hVps34 initially appear contradictory, since increased mTOR Complex1 activation is triggered by increased amino acid levels, while autophagy is triggered when cells are faced with amino acid deprivation.
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Affiliation(s)
- Takahiro Nobukuni
- Genome Research Institute, University of Cincinnati, 2180 E Galbraith Rd, Cincinnati, OH 45237, USA
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Wu EHT, Wu KKH, Wong YH. Tuberin: a stimulus-regulated tumor suppressor protein controlled by a diverse array of receptor tyrosine kinases and G protein-coupled receptors. Neurosignals 2007; 15:217-27. [PMID: 17389815 DOI: 10.1159/000101333] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2006] [Accepted: 02/09/2007] [Indexed: 02/02/2023] Open
Abstract
Tuberin, a tumor suppressor protein, is involved in various cellular functions including survival, proliferation, and growth. It has emerged as an important effector regulated by receptor tyrosine kinases (RTKs) and G protein-coupled receptors (GPCRs). Regulation of tuberin by RTKs and GPCRs is highly complex and dependent on the type of receptors and their associated signaling molecules. Apart from Akt, the first kinase recognized to phosphorylate and inactivate tuberin upon growth factor stimulation, an increasing number of kinases upstream of tuberin have been identified. Furthermore, recruitment of different scaffolding adaptor components to the activated receptors appears to play an important role in the regulation of tuberin activity. More recently, the differential regulation of tuberin by various G protein family members have also been intensively studied, it appears that G proteins can both facilitate (e.g., G(i/o)) as well as inhibit (e.g., G(q)) tuberin phosphorylation. In the present review, we attempt to summarize our emerging understandings of the roles of RTKs, GPCRs, and their cross-talk on the regulation of tuberin.
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Affiliation(s)
- Eddy H T Wu
- Department of Biochemistry, Molecular Neuroscience Center, and Biotechnology Research Institute, Hong Kong University of Science and Technology, Hong Kong, SAR, China
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33
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Yasui S, Tsuzaki K, Ninomiya H, Floricel F, Asano Y, Maki H, Takamura A, Nanba E, Higaki K, Ohno K. The TSC1 gene product hamartin interacts with NADE. Mol Cell Neurosci 2007; 35:100-8. [PMID: 17355907 DOI: 10.1016/j.mcn.2007.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Revised: 01/30/2007] [Accepted: 02/06/2007] [Indexed: 01/06/2023] Open
Abstract
Hamartomatous brain lesions are a hallmark of brain pathology of tuberous sclerosis complex (TSC). To elucidate the mechanism of tumor development in the brain of TSC, we identified NADE (p75NTR-associated cell death executor) as an interactor for TSC1 gene product hamartin using a yeast two-hybrid system. In a pull-down assay, endogenous NADE was purified with the immobilized coiled-coil domain (CCD) of hamartin from the PC12h cell lysate. Immunofluorescence and immunoprecipitation confirmed the interaction of hamartin and NADE in cultured neurons and mouse brain lysate. Hamartin constitutively associated with NADE to prevent its proteasomal degradation. Suppression of hamartin with TSC1 small interfering RNA (siRNA) caused reduction of NADE and failed to lead to NGF-induced apoptosis in PC12h cells. These results indicate that hamartin binds to NADE to regulate neuronal cell function and loss of this association is likely to contribute to the brain pathology in TSC.
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Affiliation(s)
- Sakiko Yasui
- Department of Neurobiology, School of Life Sciences, Tottori University Faculty of Medicine, Yonago 683-8503, Japan
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34
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Ramm G, Larance M, Guilhaus M, James DE. A role for 14-3-3 in insulin-stimulated GLUT4 translocation through its interaction with the RabGAP AS160. J Biol Chem 2006; 281:29174-80. [PMID: 16880201 DOI: 10.1074/jbc.m603274200] [Citation(s) in RCA: 171] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Translocation of the insulin-regulated glucose transporter GLUT4 to the cell surface is dependent on the phosphatidylinositol 3-kinase/Akt pathway. The RabGAP (Rab GTPase-activating protein) AS160 (Akt substrate of 160 kDa) is a direct substrate of Akt and plays an essential role in the regulation of GLUT4 trafficking. We have used liquid chromatography tandem mass spectrometry to identify several 14-3-3 isoforms as AS160-interacting proteins. 14-3-3 proteins interact with AS160 in an insulin- and Akt-dependent manner via an Akt phosphorylation site, Thr-642. This correlates with the dominant negative effect of both the AS160(T642A) and the AS160(4P) mutants on insulin-stimulated GLUT4 translocation. Introduction of a constitutive 14-3-3 binding site into AS160(4P) restored 14-3-3 binding without disrupting AS160-IRAP (insulin-responsive amino peptidase) interaction and reversed the inhibitory effect of AS160(4P) on GLUT4 translocation. These data show that the insulin-dependent association of 14-3-3 with AS160 plays an important role in GLUT4 trafficking in adipocytes.
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Affiliation(s)
- Georg Ramm
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, NSW, Australia.
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35
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Porter GW, Khuri FR, Fu H. Dynamic 14-3-3/client protein interactions integrate survival and apoptotic pathways. Semin Cancer Biol 2006; 16:193-202. [PMID: 16697216 DOI: 10.1016/j.semcancer.2006.03.003] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The serine/threonine binding protein, 14-3-3, possesses a diverse array of client proteins. It is involved in the regulation of apoptosis through multiple interactions with proteins of the core mitochondrial machinery, pro-apoptotic transcription factors, and their upstream signaling pathways. 14-3-3 coordinates with survival kinases to inhibit multiple pro-apoptotic molecules. One prominent mechanism for the suppression of apoptosis is through 14-3-3-mediated sequestration of pro-apoptotic client proteins. On the other hand, cellular stresses appear to signal through the inhibition of 14-3-3 function to exert their pro-apoptotic effect. Global inhibition of 14-3-3/client protein interaction induces apoptosis, and stands as an attractive intervention in diseases involving overactive survival signaling pathways. Because dysregulation of 14-3-3 has been associated with poor survival of cancer patients, targeting 14-3-3 may provide a novel therapeutic approach for the treatment of cancer.
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Affiliation(s)
- Gavin W Porter
- Department of Pharmacology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322, USA.
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36
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Liu H, Radisky DC, Nelson CM, Zhang H, Fata JE, Roth RA, Bissell MJ. Mechanism of Akt1 inhibition of breast cancer cell invasion reveals a protumorigenic role for TSC2. Proc Natl Acad Sci U S A 2006; 103:4134-9. [PMID: 16537497 PMCID: PMC1390746 DOI: 10.1073/pnas.0511342103] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Akt1 is frequently up-regulated in human tumors and has been shown to accelerate cell proliferation and to suppress programmed cell death; consequently, inhibition of the activity of Akt1 has been seen as an attractive target for therapeutic intervention. Paradoxically, hyperactivation of the Akt1 oncogene can also prevent the invasive behavior that underlies progression to metastasis. Here we show that overexpression of activated myr-Akt1 in human breast cancer cells phosphorylates and thereby targets the tumor suppressor tuberous sclerosis complex 2 (TSC2) for degradation, leading to reduced Rho-GTPase activity, decreased actin stress fibers and focal adhesions, and reduced motility and invasion. Overexpression of TSC2 rescues the migration phenotype of myr-Akt1-expressing tumor cells, and high levels of TSC2 in breast cancer patients correlate with increased metastasis and reduced survival. These data indicate that the functional properties of genes designated as oncogenes or tumor suppressor genes depend on the context of the cell type and the tissues studied, and suggest the need for caution in designing therapies targeting the function of individual genes in epithelial tissues.
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Affiliation(s)
- Hong Liu
- *Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; and
| | - Derek C. Radisky
- *Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; and
| | - Celeste M. Nelson
- *Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; and
| | - Hui Zhang
- *Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; and
| | - Jimmie E. Fata
- *Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; and
| | - Richard A. Roth
- Department of Molecular Pharmacology, Stanford University School of Medicine, Stanford, CA 94305
| | - Mina J. Bissell
- *Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; and
- To whom correspondence should be addressed. E-mail:
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37
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Lesma E, Grande V, Carelli S, Brancaccio D, Canevini MP, Alfano RM, Coggi G, Di Giulio AM, Gorio A. Isolation and growth of smooth muscle-like cells derived from tuberous sclerosis complex-2 human renal angiomyolipoma: epidermal growth factor is the required growth factor. THE AMERICAN JOURNAL OF PATHOLOGY 2005; 167:1093-103. [PMID: 16192644 PMCID: PMC1603666 DOI: 10.1016/s0002-9440(10)61198-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Tuberous sclerosis complex (TSC) is a tumor suppressor gene disorder characterized by mutations in the TSC1 or TSC2 genes. These mutations lead to the development of benign tumors involving smooth muscle cells, causing life-threatening lymphangioleiomyomatosis. We isolated and characterized two types of cells bearing a mutation in TSC2 exon 18 from a renal angiomyolipoma of a TSC patient: one population of alpha-actin-positive smooth muscle-like cells with loss of heterozygosity for the TSC2 gene (A(+) cells) and another of nonloss of heterozygosity keratin 8/18-positive epithelial-like cells (R(+) cells). Unlike control aortic vascular smooth muscle cells, A(+) cells required epidermal growth factor (EGF) to grow and substituting EGF with insulin-like growth factor (IGF)-1 failed to increase the cell number; however, omission of EGF did not cause cell loss. The A(+) cells constantly released IGF-1 into the culture medium and constitutively showed a high degree of S6K phosphorylation even when grown in serum-free medium. Exposure to antibodies against EGF and IGF-1 receptors caused a rapid loss of A(+) cells: 50% by 5 days and 100% by 12 days. Signal transduction mediated by EGF and IGF-I receptors is therefore involved in A(+) cell survival. These results may offer a novel therapeutic perspective for the treatment of TSC complications and lymphangioleiomyomatosis.
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MESH Headings
- Actins/metabolism
- Adult
- Angiomyolipoma/genetics
- Angiomyolipoma/pathology
- Aorta/cytology
- Cell Culture Techniques
- Cell Proliferation
- Cell Survival/drug effects
- DNA Mutational Analysis
- Epidermal Growth Factor/pharmacology
- Epidermal Growth Factor/physiology
- Exons
- Female
- Fluorescein-5-isothiocyanate
- Fluorescent Antibody Technique, Indirect
- Fluorescent Dyes
- Genes, Tumor Suppressor
- Genetic Markers
- Humans
- Immunohistochemistry
- Insulin-Like Growth Factor I/metabolism
- Insulin-Like Growth Factor I/pharmacology
- Keratins/metabolism
- Loss of Heterozygosity
- Microsatellite Repeats
- Muscle, Smooth/chemistry
- Muscle, Smooth/cytology
- Muscle, Smooth/growth & development
- Muscle, Smooth/metabolism
- Muscle, Smooth, Vascular/chemistry
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/growth & development
- Muscle, Smooth, Vascular/metabolism
- Mutation
- Phosphorylation
- Rhodamines
- Ribosomal Protein S6 Kinases, 70-kDa/metabolism
- Tuberous Sclerosis/genetics
- Tuberous Sclerosis/pathology
- Tuberous Sclerosis Complex 1 Protein
- Tuberous Sclerosis Complex 2 Protein
- Tumor Suppressor Proteins/genetics
- Tumor Suppressor Proteins/metabolism
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Affiliation(s)
- Elena Lesma
- Laboratory of Pharmacology, Faculty of Medicine, University of Milan, Milan, Italy
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38
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Rosner M, Hengstschläger M. 14-3-3 proteins are involved in the regulation of mammalian cell proliferation. Amino Acids 2005; 30:105-9. [PMID: 16133763 DOI: 10.1007/s00726-005-0240-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2005] [Accepted: 07/15/2005] [Indexed: 11/28/2022]
Abstract
The 14-3-3 proteins are a family of abundant, widely expressed acidic polypeptides. The seven isoforms interact with over 70 different proteins. 14-3-3 isoforms have been demonstrated to be involved in the control of positive as well as negative regulators of mammalian cell proliferation. Here we used the approach of inactivating 14-3-3 protein functions via overexpression of dominant negative mutants to analyse the role of 14-3-3 proteins in mammalian cell proliferation. We found 14-3-3 dominant negative mutants to downregulate the proliferation rates of HeLa cells. Overexpression of these dominant negative mutants triggers upregulation of the protein levels of the cyclin-dependent kinase inhibitor p27, a major negative cell cycle regulator. In addition, they downregulate the protein levels of the important cell cycle promoter cyclin D1. These data provide new insights into mammalian cell proliferation control and allow a better understanding of the functions of 14-3-3 proteins.
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Affiliation(s)
- M Rosner
- Medical Genetics, Obstetrics and Gynecology, Medical University of Vienna, Vienna, Austria
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39
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Abstract
One of the most striking 'rags to riches' stories in the protein world is that of 14-3-3, originally identified in 1967 as merely an abundant brain protein. The first clues that 14-3-3 would play an important role in cell biology came almost 25 years later when it was found to interact with various proto-oncogene proteins and signaling proteins. The subsequent identification of 14-3-3 as a phosphoserine/phosphothreonine-binding protein firmly established its importance in cell signaling. 14-3-3 family members are found in all eukaryotes - from plants to mammals - and more than 100 binding partners have been identified to date. The targets of 14-3-3 are found in all subcellular compartments and their functional diversity is overwhelming - they include transcription factors, biosynthetic enzymes, cytoskeletal proteins, signaling molecules, apoptosis factors and tumor suppressors. 14-3-3 binding can alter the localization, stability, phosphorylation state, activity and/or molecular interactions of a target protein. Recent studies now indicate that the serine/threonine protein phosphatases PP1 and PP2A are important regulators of 14-3-3 binding interactions, and demonstrate a role for 14-3-3 in controlling the translocation of certain proteins from the cytoplasmic and endoplasmic reticulum to the plasma membrane. New reports also link 14-3-3 to several neoplastic and neurological disorders, where it might contribute to the pathogenesis and progression of these diseases.
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Affiliation(s)
- Michele K Dougherty
- Laboratory of Protein Dynamics and Signaling, NCI-Frederick, Frederick, MD 21702, USA
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40
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Abstract
The evolutionarily conserved checkpoint protein kinase, TOR (target of rapamycin), has emerged as a major effector of cell growth and proliferation via the regulation of protein synthesis. Work in the last decade clearly demonstrates that TOR controls protein synthesis through a stunning number of downstream targets. Some of the targets are phosphorylated directly by TOR, but many are phosphorylated indirectly. In this review, we summarize some recent developments in this fast-evolving field. We describe both the upstream components of the signaling pathway(s) that activates mammalian TOR (mTOR) and the downstream targets that affect protein synthesis. We also summarize the roles of mTOR in the control of cell growth and proliferation, as well as its relevance to cancer and synaptic plasticity.
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Affiliation(s)
- Nissim Hay
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, 60607, USA.
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41
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Meek SEM, Lane WS, Piwnica-Worms H. Comprehensive proteomic analysis of interphase and mitotic 14-3-3-binding proteins. J Biol Chem 2004; 279:32046-54. [PMID: 15161933 DOI: 10.1074/jbc.m403044200] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
14-3-3 proteins regulate the cell division cycle and play a pivotal role in blocking cell cycle advancement after activation of the DNA replication and DNA damage checkpoints. Here we describe a global proteomics analysis to identify proteins that bind to 14-3-3s during interphase and mitosis. 14-3-3-binding proteins were purified from extracts of interphase and mitotic HeLa cells using specific peptide elution from 14-3-3 zeta affinity columns. Proteins that specifically bound and eluted from the affinity columns were identified by microcapillary high pressure liquid chromatography tandem mass spectrometry analysis. Several known and novel 14-3-3-interacting proteins were identified in this screen. Identified proteins are involved in cell cycle regulation, signaling, metabolism, protein synthesis, nucleic acid binding, chromatin structure, protein folding, proteolysis, nucleolar function, and nuclear transport as well as several other cellular processes. In some cases 14-3-3 binding was cell cycle-dependent, whereas in other cases the binding was shown to be cell cycle-independent. This study adds to the growing list of human 14-3-3-binding proteins and implicates a role for 14-3-3 proteins in a plethora of essential biological processes.
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Affiliation(s)
- Sarah E M Meek
- Howard Hughes Medical Institute, Harvard University, Cambridge, Massachusetts 02138, USA
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42
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Saito A, Narasimhan P, Hayashi T, Okuno S, Ferrand-Drake M, Chan PH. Neuroprotective role of a proline-rich Akt substrate in apoptotic neuronal cell death after stroke: relationships with nerve growth factor. J Neurosci 2004; 24:1584-93. [PMID: 14973226 PMCID: PMC6730448 DOI: 10.1523/jneurosci.5209-03.2004] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The Akt signaling pathway contributes to regulation of apoptosis after a variety of cell death stimuli. A novel proline-rich Akt substrate (PRAS) was recently detected and found to be involved in apoptosis. In our study, Akt activation was modulated by growth factors, and treatment with nerve growth factor (NGF) reduced apoptotic cell death after ischemic injury. However, the role of the PRAS pathway in apoptotic neuronal cell death after ischemia remains unknown. Phosphorylated PRAS (pPRAS) and the binding of pPRAS/phosphorylated Akt (pPRAS/pAkt) to 14-3-3 (pPRAS/14-3-3) were detected, and their expression transiently decreased in mouse brains after transient focal cerebral ischemia (tFCI). Liposome-mediated pPRAS cDNA transfection induced overexpression of pPRAS, promoted pPRAS/14-3-3, and inhibited apoptotic neuronal cell death after tFCI. The expression of pPRAS, pPRAS/pAkt, and pPRAS/14-3-3 increased in NGF-treated mice but decreased with inhibition of phosphatidylinositol-3 kinase and the NGF receptor after tFCI. These results suggest that PRAS phosphorylation and its interaction with pAkt and 14-3-3 might play an important role in neuroprotection mediated by NGF in apoptotic neuronal cell death after tFCI.
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Affiliation(s)
- Atsushi Saito
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, California 94305-5487, USA
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43
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Affiliation(s)
- Mary-Ann Bjornsti
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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44
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Yu J, Astrinidis A, Howard S, Henske EP. Estradiol and tamoxifen stimulate LAM-associated angiomyolipoma cell growth and activate both genomic and nongenomic signaling pathways. Am J Physiol Lung Cell Mol Physiol 2004; 286:L694-700. [PMID: 12922981 DOI: 10.1152/ajplung.00204.2003] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lymphangioleiomyomatosis (LAM) is a progressive lung disease affecting almost exclusively women. The reasons for this strong gender predisposition are poorly understood. Renal angiomyolipomas occur in 50-60% of sporadic LAM patients. The smooth muscle cells of pulmonary LAM and renal angiomyolipomas are nearly indistinguishable morphologically. Here, we report the first successful cell culture of a LAM-associated renal angiomyolipoma. The cells carried inactivating mutations in both alleles of the TSC2 gene and expressed estrogen receptor , estrogen receptor , and androgen receptor. To elucidate the cellular pathways through which steroid hormones influence LAM pathogenesis, we treated the cells with both estradiol and tamoxifen. Cell growth was stimulated by estradiol, associated with phosphorylation of p44/42 MAPK at 5 min and an increase in c-myc expression at 4 h. Tamoxifen citrate also stimulated cell growth, associated with increased phosphorylation of p44/42 MAPK and expression of c-myc, indicating that tamoxifen has agonist effects on angiomyolipoma cells. This response to tamoxifen in human angiomyolipoma cells differs from prior studies of Eker rat leiomyoma cells, possibly reflecting cell type or species differences in cells lacking tuberin. Our data provide the first evidence that estradiol stimulates the growth of angiomyolipoma cells, that tamoxifen has agonist effects in angiomyolipoma cells, and that estradiol and tamoxifen impact both genomic and nongenomic signaling pathways in angiomyolipoma cells. The responsiveness of angiomyolipoma cells to estradiol may be related to the underlying reasons that LAM affects primarily women.
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Affiliation(s)
- Jane Yu
- Fox Chase Cancer Center, 7701 Burholme Ave., Philadelphia, PA 19111, USA
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45
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Abstract
Recent research has examined Akt and Akt-related serine-threonine kinases in signaling cascades that regulate cell survival and are important in the pathogenesis of degenerative diseases and in cancer. We seek to recapitulate the research that has helped to define the current understanding of the role of the Akt pathway under normal and pathologic conditions, also in view of genetic models of Akt function. In particular, we will evaluate the mechanisms of Akt regulation and the role of Akt substrates in Akt-dependent biologic responses in the decisions of cell death and cell survival. Here, we hope to establish the mechanisms of apoptosis suppression by Akt kinase as a framework for a more general understanding of growth factor-dependent regulation of cell survival.
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Affiliation(s)
- Thomas F Franke
- Department of Pharmacology, College of Physicians & Surgeons, Columbia University, 630 West 168th Street, PH7-W318, New York, NY 10032, USA.
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46
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Hengstschläger M, Rosner M, Fountoulakis M, Lubec G. Tuberous sclerosis genes regulate cellular 14-3-3 protein levels. Biochem Biophys Res Commun 2003; 312:676-83. [PMID: 14680818 DOI: 10.1016/j.bbrc.2003.10.170] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2003] [Indexed: 10/26/2022]
Abstract
The genes TSC1, encoding hamartin, and TSC2, encoding tuberin are responsible for tuberous sclerosis. This autosomal dominant tumor suppressor gene syndrome affects about 1 in 6000 individuals. A variety of tumors characteristically occur in different organs of tuberous sclerosis patients and are believed to result from defects in cell cycle/cell size control. We performed a proteomics approach of two-dimensional gel electrophoresis with subsequent mass spectrometrical identification of protein spots after ectopic overexpression of human TSC1 or TSC2. We found the cellular levels of four isoforms of the 14-3-3 protein family, 14-3-3 gamma, 14-3-3, 14-3-3 sigma, and 14-3-3 zeta, to be regulated by the two tuberous sclerosis gene products. In the same experiments the protein levels of keratin 7, capZ alpha-1 subunit, ezrin, and nedasin were not affected by ectopic TSC1 or TSC2. Western blot analyses confirmed the deregulation of 14-3-3 proteins upon ectopic overexpression of TSC1 and TSC2. A TSC1 mutant not encoding the transmembrane domain and the tuberin-binding domain but harbouring most of the coiled-coil region and the ERM protein interaction domain of hamartin did not affect 14-3-3 protein levels. The here presented findings suggest that deregulation of 14-3-3 protein amounts might contribute to the development of tumors in tuberous sclerosis patients. These data provide important new insights into the molecular development of this disease especially since both, the TSC genes and the 14-3-3 proteins, are known to be involved in mammalian cell cycle control.
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Affiliation(s)
- Markus Hengstschläger
- Obstetrics and Gynecology, University of Vienna, Prenatal Diagnosis and Therapy, Währinger Gürtel 18-20, Vienna A-1090, Austria
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47
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Shamji AF, Nghiem P, Schreiber SL. Integration of growth factor and nutrient signaling: implications for cancer biology. Mol Cell 2003; 12:271-80. [PMID: 14536067 DOI: 10.1016/j.molcel.2003.08.016] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Signaling networks that promote cell growth are frequently dysregulated in cancer. One regulatory network, which converges on effectors such as 4EBP1 and S6K1, leads to growth by promoting protein synthesis. Here, we discuss how this network is regulated by both extracellular signals, such as growth factors, and intracellular signals, such as nutrients. We discuss how mutations amplifying either type of signal can lead to tumor formation. In particular, we focus on the recent discovery that a tumor suppressor complex whose function is lost in tuberous sclerosis patients regulates the nutrient signal carried by the critical signaling protein TOR to the effectors 4EBP1 and S6K1. Finally, we describe how the small molecule rapamycin, which inhibits TOR and thereby the activation of these effectors, could be useful to treat tumors that have become dependent upon this pathway for growth.
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Affiliation(s)
- Alykhan F Shamji
- Harvard Biophysics Program, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA
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48
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Astrinidis A, Senapedis W, Coleman TR, Henske EP. Cell cycle-regulated phosphorylation of hamartin, the product of the tuberous sclerosis complex 1 gene, by cyclin-dependent kinase 1/cyclin B. J Biol Chem 2003; 278:51372-9. [PMID: 14551205 DOI: 10.1074/jbc.m303956200] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tuberous sclerosis complex is a tumor suppressor gene syndrome whose manifestations can include seizures, mental retardation, and benign tumors of the brain, skin, heart, and kidneys. Hamartin and tuberin, the products of the TSC1 and TSC2 genes, respectively, form a complex and inhibit signaling by the mammalian target of rapamycin. Here, we demonstrate that endogenous hamartin is threonine-phosphorylated during nocodazole-induced G2/M arrest and during the G2/M phase of a normal cell cycle. In vitro assays showed that cyclin-dependent kinase 1 phosphorylates hamartin at three sites, one of which (Thr417) is in the hamartin-tuberin interaction domain. Tuberin interacts with phosphohamartin, and tuberin expression attenuates the phosphorylation of exogenous hamartin. Hamartin with alanine mutations in the three cyclin-dependent kinase 1 phosphorylation sites increased the inhibition of p70S6 kinase by the hamartin-tuberin complex. These findings support a model in which phosphorylation of hamartin regulates the function of the hamartin-tuberin complex during the G2/M phase of the cell cycle.
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49
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Tee AR, Anjum R, Blenis J. Inactivation of the tuberous sclerosis complex-1 and -2 gene products occurs by phosphoinositide 3-kinase/Akt-dependent and -independent phosphorylation of tuberin. J Biol Chem 2003; 278:37288-96. [PMID: 12867426 DOI: 10.1074/jbc.m303257200] [Citation(s) in RCA: 165] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The tuberous sclerosis complex (TSC) is a genetic disorder that is caused through mutations in either one of the two tumor suppressor genes, TSC1 and TSC2, that encode hamartin and tuberin, respectively. Interaction of hamartin with tuberin forms a heterodimer that inhibits signaling by the mammalian target of rapamycin to its downstream targets: eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) and ribosomal protein S6 kinase 1 (S6K1). During mitogenic sufficiency, the phosphoinositide 3-kinase (PI3K)/Akt pathway phosphorylates tuberin on Ser-939 and Thr-1462 that inhibits the tumor suppressor function of the TSC complex. Here we show that tuberin-hamartin heterodimers block protein kinase C (PKC)/MAPK- and phosphatidic acid-mediated signaling toward mammalian target of rapamycin-dependent targets. We also show that two TSC2 mutants derived from TSC patients are defective in repressing phorbol 12-myristate 13-acetate-induced 4E-BP1 phosphorylation. PKC/MAPK signaling leads to phosphorylation of tuberin at sites that overlap with and are distinct from Akt phosphorylation sites. Phosphorylation of tuberin by phorbol 12-myristate 13-acetate was reduced by treatment of cells with either bisindolylmaleimide I or UO126, inhibitors of PKC and MAPK/MEK (MAPK/ERK kinase), respectively, but not by wortmannin (an inhibitor of PI3K). This work reveals that both PI3K-independent and -dependent mechanisms modulate tuberin phosphorylation in vivo.
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Affiliation(s)
- Andrew R Tee
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Abstract
Tumour suppressors hamartin and tuberin, encoded by tuberous sclerosis complex 1(TSC1) and TSC2 genes, respectively, are critical regulators of cell growth and proliferation. Mutations in TSC1 and TSC2 genes are the cause of an autosomal dominant disorder known as tuberous sclerosis complex (TSC). Another genetic disorder, lymphangioleiomyomatosis (LAM), is also associated with mutations in the TSC2 gene. Hamartin and tuberin control cell growth by negatively regulating S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E binding protein 1 (4E-BP1), potentially through their upstream modulator mammalian target of rapamycin (mTOR). Growth factors and insulin promote Akt/PKB-dependent phosphorylation of tuberin, which in turn, releases S6K1 from negative regulation by tuberin and results in the activation of S6K1. Although much has been written regarding the molecular genetics of TSC and LAM, which is associated with either the loss of or mutation in the TSC1 and TSC2 genes, few reviews have addressed the intracellular signalling pathways regulated by hamartin and tuberin. The current review will fill the gap in our understanding of their role in cellular signalling networks, and by improving this understanding, an integrated picture regarding the normal function of tuberin and hamartin is beginning to emerge.
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Affiliation(s)
- Vera P Krymskaya
- Pulmonary, Allergy and Critical Care Division, Department of Medicine, University of Pennsylvania, 421 Curie Boulevard, 847 BRB II/III, Philadelphia, PA 19104-6160, USA.
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