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Rodriguez-Colman MJ, Dansen TB, Burgering BMT. FOXO transcription factors as mediators of stress adaptation. Nat Rev Mol Cell Biol 2024; 25:46-64. [PMID: 37710009 DOI: 10.1038/s41580-023-00649-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2023] [Indexed: 09/16/2023]
Abstract
The forkhead box protein O (FOXO, consisting of FOXO1, FOXO3, FOXO4 and FOXO6) transcription factors are the mammalian orthologues of Caenorhabditis elegans DAF-16, which gained notoriety for its capability to double lifespan in the absence of daf-2 (the gene encoding the worm insulin receptor homologue). Since then, research has provided many mechanistic details on FOXO regulation and FOXO activity. Furthermore, conditional knockout experiments have provided a wealth of data as to how FOXOs control development and homeostasis at the organ and organism levels. The lifespan-extending capabilities of DAF-16/FOXO are highly correlated with their ability to induce stress response pathways. Exogenous and endogenous stress, such as cellular redox stress, are considered the main drivers of the functional decline that characterizes ageing. Functional decline often manifests as disease, and decrease in FOXO activity indeed negatively impacts on major age-related diseases such as cancer and diabetes. In this context, the main function of FOXOs is considered to preserve cellular and organismal homeostasis, through regulation of stress response pathways. Paradoxically, the same FOXO-mediated responses can also aid the survival of dysfunctional cells once these eventually emerge. This general property to control stress responses may underlie the complex and less-evident roles of FOXOs in human lifespan as opposed to model organisms such as C. elegans.
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Affiliation(s)
| | - Tobias B Dansen
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, Netherlands
| | - Boudewijn M T Burgering
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, Netherlands.
- Oncode Institute, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, Netherlands.
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Moore XTR, Gheghiani L, Fu Z. The Role of Polo-Like Kinase 1 in Regulating the Forkhead Box Family Transcription Factors. Cells 2023; 12:cells12091344. [PMID: 37174744 PMCID: PMC10177174 DOI: 10.3390/cells12091344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 05/01/2023] [Accepted: 05/05/2023] [Indexed: 05/15/2023] Open
Abstract
Polo-like kinase 1 (PLK1) is a serine/threonine kinase with more than 600 phosphorylation substrates through which it regulates many biological processes, including mitosis, apoptosis, metabolism, RNA processing, vesicle transport, and G2 DNA-damage checkpoint recovery, among others. Among the many PLK1 targets are members of the FOX family of transcription factors (FOX TFs), including FOXM1, FOXO1, FOXO3, and FOXK1. FOXM1 and FOXK1 have critical oncogenic roles in cancer through their antagonism of apoptotic signals and their promotion of cell proliferation, metastasis, angiogenesis, and therapeutic resistance. In contrast, FOXO1 and FOXO3 have been identified to have broad functions in maintaining cellular homeostasis. In this review, we discuss PLK1-mediated regulation of FOX TFs, highlighting the effects of PLK1 on the activity and stability of these proteins. In addition, we review the prognostic and clinical significance of these proteins in human cancers and, more importantly, the different approaches that have been used to disrupt PLK1 and FOX TF-mediated signaling networks. Furthermore, we discuss the therapeutic potential of targeting PLK1-regulated FOX TFs in human cancers.
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Affiliation(s)
- Xavier T R Moore
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284, USA
| | - Lilia Gheghiani
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Zheng Fu
- Department of Human and Molecular Genetics, VCU Institute of Molecular Medicine, Massey Cancer Center, Virginia Commonwealth University, School of Medicine, Richmond, VA 23298, USA
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Ostalé CM, Esteban N, López-Varea A, de Celis JF. Functional requirements of protein kinases and phosphatases in the development of the Drosophila melanogaster wing. G3-GENES GENOMES GENETICS 2021; 11:6380433. [PMID: 34599799 PMCID: PMC8664455 DOI: 10.1093/g3journal/jkab348] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 09/06/2021] [Indexed: 11/14/2022]
Abstract
Protein kinases and phosphatases constitute a large family of conserved enzymes that control a variety of biological processes by regulating the phosphorylation state of target proteins. They play fundamental regulatory roles during cell cycle progression and signaling, among other key aspects of multicellular development. The complement of protein kinases and phosphatases includes approximately 326 members in Drosophila, and they have been the subject of several functional screens searching for novel components of signaling pathways and regulators of cell division and survival. These approaches have been carried out mostly in cell cultures using RNA interference to evaluate the contribution of each protein in different functional assays, and have contributed significantly to assign specific roles to the corresponding genes. In this work we describe the results of an evaluation of the Drosophila complement of kinases and phosphatases using the wing as a system to identify their functional requirements in vivo. We also describe the results of several modifying screens aiming to identify among the set of protein kinases and phosphatases additional components or regulators of the activities of the Epidermal Growth Factor and Insulin receptors signaling pathways.
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Affiliation(s)
- Cristina M Ostalé
- Centro de Biología Molecular "Severo Ochoa", CSIC and Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Nuria Esteban
- Centro de Biología Molecular "Severo Ochoa", CSIC and Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Ana López-Varea
- Centro de Biología Molecular "Severo Ochoa", CSIC and Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Jose F de Celis
- Centro de Biología Molecular "Severo Ochoa", CSIC and Universidad Autónoma de Madrid, Madrid 28049, Spain
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Recovery of muscle mass and muscle oxidative phenotype following disuse does not require GSK-3 inactivation. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165740. [PMID: 32087280 DOI: 10.1016/j.bbadis.2020.165740] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/24/2020] [Accepted: 02/18/2020] [Indexed: 12/22/2022]
Abstract
BACKGROUND Physical inactivity contributes to muscle wasting and reductions in mitochondrial oxidative phenotype (OXPHEN), reducing physical performance and quality of life during aging and in chronic disease. Previously, it was shown that inactivation of glycogen synthase kinase (GSK)-3β stimulates muscle protein accretion, myogenesis, and mitochondrial biogenesis. Additionally, GSK-3β is inactivated during recovery of disuse-induced muscle atrophy. AIM Therefore, we hypothesize that GSK-3 inhibition is required for reloading-induced recovery of skeletal muscle mass and OXPHEN. METHODS Wild-type (WT) and whole-body constitutively active (C.A.) Ser21/9 GSK-3α/β knock-in mice were subjected to a 14-day hind-limb suspension/14-day reloading protocol. Soleus muscle mass, fiber cross-sectional area (CSA), OXPHEN (abundance of sub-units of oxidative phosphorylation (OXPHOS) complexes and fiber-type composition), as well as expression levels of their main regulators (respectively protein synthesis/degradation, myogenesis and peroxisome proliferator-activated receptor-γ co-activator-1α (PGC-1α) signaling) were monitored. RESULTS Subtle but consistent differences suggesting suppression of protein turnover signaling and decreased expression of several OXPHOS sub-units and PGC-1α signaling constituents were observed at baseline in C.A. GSK-3 versus WT mice. Although soleus mass recovery during reloading occurred more rapidly in C.A. GSK-3 mice, this was not accompanied by a parallel increased CSA. The OXPHEN response to reloading was not distinct between C.A. GSK-3 and WT mice. No consistent or significant differences in reloading-induced changes in the regulatory steps of protein turnover, myogenesis or muscle OXPHEN were observed in C.A. GSK-3 compared to WT muscle. CONCLUSION This study indicates that GSK-3 inactivation is dispensable for reloading-induced recovery of muscle mass and OXPHEN.
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Cis- and trans-acting variants contribute to survivorship in a naïve Drosophila melanogaster population exposed to ryanoid insecticides. Proc Natl Acad Sci U S A 2019; 116:10424-10429. [PMID: 31064874 PMCID: PMC6535026 DOI: 10.1073/pnas.1821713116] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Around the world insecticides are being deregistered and banned, as their environmental costs are deemed too great or their efficacy against pest insects is reduced through the evolution of insecticide resistance. With the introduction of replacement insecticides comes the responsibility to assess the way new insecticides perturb various levels of biological systems, from insect physiology to ecosystems. We used a systems genetics approach to identify genetic variants affecting survivorship of Drosophila melanogaster exposed to chlorantraniliprole. The study population was completely naïve to this insecticide chemistry and yet we find associations with variants in neuromuscular genes and coregulated detoxification genes. We predict that these variants will increase in populations of this “sentinel species” as these insecticides are applied in the environment. Insecticide resistance is a paradigm of microevolution, and insecticides are responsible for the strongest cases of recent selection in the genome of Drosophila melanogaster. Here we use a naïve population and a novel insecticide class to examine the ab initio genetic architecture of a potential selective response. Genome-wide association studies (GWAS) of chlorantraniliprole susceptibility reveal variation in a gene of major effect, Stretchin Myosin light chain kinase (Strn-Mlck), which we validate with linkage mapping and transgenic manipulation of gene expression. We propose that allelic variation in Strn-Mlck alters sensitivity to the calcium depletion attributable to chlorantraniliprole’s mode of action. GWAS also reveal a network of genes involved in neuromuscular biology. In contrast, phenotype to transcriptome associations identify differences in constitutive levels of multiple transcripts regulated by cnc, the homolog of mammalian Nrf2. This suggests that genetic variation acts in trans to regulate multiple metabolic enzymes in this pathway. The most outstanding association is with the transcription level of Cyp12d1 which is also affected in cis by copy number variation. Transgenic overexpression of Cyp12d1 reduces susceptibility to both chlorantraniliprole and the closely related insecticide cyantraniliprole. This systems genetics study reveals multiple allelic variants segregating at intermediate frequency in a population that is completely naïve to this new insecticide chemistry and it foreshadows a selective response among natural populations to these chemicals.
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Role of Forkhead Box O Transcription Factors in Oxidative Stress-Induced Chondrocyte Dysfunction: Possible Therapeutic Target for Osteoarthritis? Int J Mol Sci 2018. [PMID: 30487470 DOI: 10.3390/ijms19123794.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Chondrocyte dysfunction occurs during the development of osteoarthritis (OA), typically resulting from a deleterious increase in oxidative stress. Accordingly, strategies for arresting oxidative stress-induced chondrocyte dysfunction may lead to new potential therapeutic targets for OA treatment. Forkhead box O (FoxO) transcription factors have recently been shown to play a protective role in chondrocyte dysfunction through the regulation of inflammation, autophagy, aging, and oxidative stress. They also regulate growth, maturation, and matrix synthesis in chondrocytes. In this review, we discuss the recent progress made in the field of oxidative stress-induced chondrocyte dysfunction. We also discuss the protective role of FoxO transcription factors as potential molecular targets for the treatment of OA. Understanding the function of FoxO transcription factors in the OA pathology may provide new insights that will facilitate the development of next-generation therapies to prevent OA development and to slow OA progression.
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Wang R, Zhang S, Previn R, Chen D, Jin Y, Zhou G. Role of Forkhead Box O Transcription Factors in Oxidative Stress-Induced Chondrocyte Dysfunction: Possible Therapeutic Target for Osteoarthritis? Int J Mol Sci 2018; 19:ijms19123794. [PMID: 30487470 PMCID: PMC6321605 DOI: 10.3390/ijms19123794] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 11/22/2018] [Accepted: 11/24/2018] [Indexed: 12/11/2022] Open
Abstract
Chondrocyte dysfunction occurs during the development of osteoarthritis (OA), typically resulting from a deleterious increase in oxidative stress. Accordingly, strategies for arresting oxidative stress-induced chondrocyte dysfunction may lead to new potential therapeutic targets for OA treatment. Forkhead box O (FoxO) transcription factors have recently been shown to play a protective role in chondrocyte dysfunction through the regulation of inflammation, autophagy, aging, and oxidative stress. They also regulate growth, maturation, and matrix synthesis in chondrocytes. In this review, we discuss the recent progress made in the field of oxidative stress-induced chondrocyte dysfunction. We also discuss the protective role of FoxO transcription factors as potential molecular targets for the treatment of OA. Understanding the function of FoxO transcription factors in the OA pathology may provide new insights that will facilitate the development of next-generation therapies to prevent OA development and to slow OA progression.
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Affiliation(s)
- Rikang Wang
- Shenzhen Key Laboratory for Anti-ageing and Regenerative Medicine, Guangdong Key Laboratory for Genome Stability and Disease Prevention, Department of Medical Cell Biology and Genetics, Shenzhen University Health Science Center, Shenzhen 518060, China.
- National Pharmaceutical Engineering Center for Solid Preparation in Chinese Herbal Medicine, Jiangxi University of Traditional Chinese Medicine, Nanchang 330006, China.
| | - Shuai Zhang
- Shenzhen Key Laboratory for Anti-ageing and Regenerative Medicine, Guangdong Key Laboratory for Genome Stability and Disease Prevention, Department of Medical Cell Biology and Genetics, Shenzhen University Health Science Center, Shenzhen 518060, China.
| | - Rahul Previn
- Shenzhen Key Laboratory for Anti-ageing and Regenerative Medicine, Guangdong Key Laboratory for Genome Stability and Disease Prevention, Department of Medical Cell Biology and Genetics, Shenzhen University Health Science Center, Shenzhen 518060, China.
| | - Di Chen
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612, USA.
| | - Yi Jin
- National Pharmaceutical Engineering Center for Solid Preparation in Chinese Herbal Medicine, Jiangxi University of Traditional Chinese Medicine, Nanchang 330006, China.
| | - Guangqian Zhou
- Shenzhen Key Laboratory for Anti-ageing and Regenerative Medicine, Guangdong Key Laboratory for Genome Stability and Disease Prevention, Department of Medical Cell Biology and Genetics, Shenzhen University Health Science Center, Shenzhen 518060, China.
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8
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You S, Li H, Hu Z, Zhang W. eIF2α kinases PERK and GCN2 act on FOXO to potentiate FOXO activity. Genes Cells 2018; 23:786-793. [PMID: 30043468 DOI: 10.1111/gtc.12625] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 06/04/2018] [Accepted: 06/21/2018] [Indexed: 12/12/2022]
Abstract
PERK and GCN2 are eIF2α kinases known to mediate the effects of ER stress and respond to an array of diverse stress stimuli. Previously, we reported that ER stress potentiates insulin resistance through PERK-mediated FOXO phosphorylation. Inhibition of PERK improves cellular insulin responsiveness at the level of FOXO activity. Here we provide further evidence that FOXO is required for the functional output of PERK by showing that lowering FOXO activity ameliorates a PERK gain-of-function phenotype in Drosophila. More importantly, we present results demonstrating that GCN2 acts similarly to PERK to promote FOXO activity. Regulation of FOXO by GCN2 is evolutionarily conserved and can be compensated for by PERK. The combination of these mechanisms may contribute to the complex regulatory network between PERK, GCN2, and FOXO, which has been implicated in the development and progression of a variety of diseases.
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Affiliation(s)
- Shiqiu You
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Huifang Li
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Zhubing Hu
- College of Life Science, Nanjing Agricultural University, Nanjing, China
| | - Wei Zhang
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
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9
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Tsakiri EN, Gaboriaud-Kolar N, Iliaki KK, Tchoumtchoua J, Papanagnou ED, Chatzigeorgiou S, Tallas KD, Mikros E, Halabalaki M, Skaltsounis AL, Trougakos IP. The Indirubin Derivative 6-Bromoindirubin-3'-Oxime Activates Proteostatic Modules, Reprograms Cellular Bioenergetic Pathways, and Exerts Antiaging Effects. Antioxid Redox Signal 2017; 27:1027-1047. [PMID: 28253732 PMCID: PMC5651956 DOI: 10.1089/ars.2016.6910] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
AIMS Organismal aging can be delayed by mutations that either activate stress responses or reduce the nutrient-sensing pathway signaling; thus, by using Drosophila melanogaster as an in vivo experimental screening platform, we searched for compounds that modulate these pathways. RESULTS We noted that oral administration of the glycogen synthase kinase 3 (Gsk-3) inhibitor 6-bromoindirubin-3'-oxime (6BIO) in Drosophila flies extended healthy life span. 6BIO is not metabolized in fly tissues, modulated bioenergetic pathways, decreased lipid and glucose tissue load, activated antioxidant and proteostatic modules, and enhanced resistance to stressors. Mechanistically, we found that the effects on the stress-responsive pathways were largely dependent on the activity of the transcription factor nuclear factor erythroid 2-related factor (Nrf-2). Genetic inhibition of Gsk-3 largely phenocopied the 6BIO-mediated effects, while high levels of Gsk-3 expression and/or kinase activity suppressed proteostatic modules and reduced flies' longevity; these effects were partially rescued by 6BIO. Also, 6BIO was found to partially reduce the 3-phosphoinositide-dependent protein kinase-1 (Pdpk1) activity, a major effector of the insulin/insulin-like growth factor-1 cell signaling pathways. INNOVATION 6BIO exerts the unique property of increasing stress tolerance and in parallel partially suppressing the nutrient-sensing pathway signaling. CONCLUSION Our findings suggest that the 6BIO scaffold can be used for the development of novel antiaging compounds. Antioxid. Redox Signal. 27, 1027-1047.
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Affiliation(s)
- Eleni N Tsakiri
- 1 Department of Cell Biology and Biophysics, Faculty of Biology, National and Kapodistrian University of Athens , Athens, Greece
| | - Nicolas Gaboriaud-Kolar
- 2 Department of Pharmacognosy and Natural Products Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens , Athens, Greece
| | - Kalliopi K Iliaki
- 1 Department of Cell Biology and Biophysics, Faculty of Biology, National and Kapodistrian University of Athens , Athens, Greece
| | - Job Tchoumtchoua
- 2 Department of Pharmacognosy and Natural Products Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens , Athens, Greece
| | - Eleni-Dimitra Papanagnou
- 1 Department of Cell Biology and Biophysics, Faculty of Biology, National and Kapodistrian University of Athens , Athens, Greece
| | - Sofia Chatzigeorgiou
- 1 Department of Cell Biology and Biophysics, Faculty of Biology, National and Kapodistrian University of Athens , Athens, Greece
| | - Konstantinos D Tallas
- 1 Department of Cell Biology and Biophysics, Faculty of Biology, National and Kapodistrian University of Athens , Athens, Greece
| | - Emmanuel Mikros
- 3 Department of Pharmaceutical Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens , Athens, Greece
| | - Maria Halabalaki
- 2 Department of Pharmacognosy and Natural Products Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens , Athens, Greece
| | - Alexios-Leandros Skaltsounis
- 2 Department of Pharmacognosy and Natural Products Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens , Athens, Greece
| | - Ioannis P Trougakos
- 1 Department of Cell Biology and Biophysics, Faculty of Biology, National and Kapodistrian University of Athens , Athens, Greece
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10
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Alfa RW, Kim SK. Using Drosophila to discover mechanisms underlying type 2 diabetes. Dis Model Mech 2016; 9:365-76. [PMID: 27053133 PMCID: PMC4852505 DOI: 10.1242/dmm.023887] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mechanisms of glucose homeostasis are remarkably well conserved between the fruit flyDrosophila melanogasterand mammals. From the initial characterization of insulin signaling in the fly came the identification of downstream metabolic pathways for nutrient storage and utilization. Defects in these pathways lead to phenotypes that are analogous to diabetic states in mammals. These discoveries have stimulated interest in leveraging the fly to better understand the genetics of type 2 diabetes mellitus in humans. Type 2 diabetes results from insulin insufficiency in the context of ongoing insulin resistance. Although genetic susceptibility is thought to govern the propensity of individuals to develop type 2 diabetes mellitus under appropriate environmental conditions, many of the human genes associated with the disease in genome-wide association studies have not been functionally studied. Recent advances in the phenotyping of metabolic defects have positionedDrosophilaas an excellent model for the functional characterization of large numbers of genes associated with type 2 diabetes mellitus. Here, we examine results from studies modeling metabolic disease in the fruit fly and compare findings to proposed mechanisms for diabetic phenotypes in mammals. We provide a systematic framework for assessing the contribution of gene candidates to insulin-secretion or insulin-resistance pathways relevant to diabetes pathogenesis.
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Affiliation(s)
- Ronald W Alfa
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA Neuroscience Program, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Seung K Kim
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA Department of Medicine (Oncology), Stanford University School of Medicine, Stanford, CA 94305, USA
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11
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Wu C, Chen Y, Wang F, Chen C, Zhang S, Li C, Li W, Wu S, Xue L. Pelle Modulates dFoxO-Mediated Cell Death in Drosophila. PLoS Genet 2015; 11:e1005589. [PMID: 26474173 PMCID: PMC4608839 DOI: 10.1371/journal.pgen.1005589] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 09/17/2015] [Indexed: 12/31/2022] Open
Abstract
Interleukin-1 receptor-associated kinases (IRAKs) are crucial mediators of the IL-1R/TLR signaling pathways that regulate the immune and inflammation response in mammals. Recent studies also suggest a critical role of IRAKs in tumor development, though the underlying mechanism remains elusive. Pelle is the sole Drosophila IRAK homolog implicated in the conserved Toll pathway that regulates Dorsal/Ventral patterning, innate immune response, muscle development and axon guidance. Here we report a novel function of pll in modulating apoptotic cell death, which is independent of the Toll pathway. We found that loss of pll results in reduced size in wing tissue, which is caused by a reduction in cell number but not cell size. Depletion of pll up-regulates the transcription of pro-apoptotic genes, and triggers caspase activation and cell death. The transcription factor dFoxO is required for loss-of-pll induced cell death. Furthermore, loss of pll activates dFoxO, promotes its translocation from cytoplasm to nucleus, and up-regulates the transcription of its target gene Thor/4E-BP. Finally, Pll physically interacts with dFoxO and phosphorylates dFoxO directly. This study not only identifies a previously unknown physiological function of pll in cell death, but also shed light on the mechanism of IRAKs in cell survival/death during tumorigenesis.
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Affiliation(s)
- Chenxi Wu
- Department of Interventional Radiology, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Yujun Chen
- Department of Interventional Radiology, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Feng Wang
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin, China
| | - Changyan Chen
- Department of Interventional Radiology, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Shiping Zhang
- Department of Interventional Radiology, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Chaojie Li
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin, China
| | - Wenzhe Li
- Department of Interventional Radiology, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Shian Wu
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin, China
| | - Lei Xue
- Department of Interventional Radiology, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai, China
- * E-mail:
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12
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The drosophila T-box transcription factor midline functions within Insulin/Akt and c-Jun-N terminal kinase stress-reactive signaling pathways to regulate interommatial bristle formation and cell survival. Mech Dev 2015; 136:8-29. [PMID: 25748605 DOI: 10.1016/j.mod.2015.02.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 02/16/2015] [Accepted: 02/17/2015] [Indexed: 02/04/2023]
Abstract
We recently reported that the T-box transcription factor midline (mid) functions within the Notch-Delta signaling pathway to specify sensory organ precursor (SOP) cell fates in early-staged pupal eye imaginal discs and to suppress apoptosis (Das et al.). From genetic and allelic modifier screens, we now report that mid interacts with genes downstream of the insulin receptor(InR)/Akt, c-Jun-N-terminal kinase (JNK) and Notch signaling pathways to regulate interommatidial bristle (IOB) formation and cell survival. One of the most significant mid-interacting genes identified from the modifier screen is dFOXO, a transcription factor exhibiting a nucleocytoplasmic subcellular distribution pattern. In common with dFOXO, we show that Mid exhibits a nucleocytoplasmic distribution pattern within WT third-instar larval (3(o)L) tissue homogenates. Because dFOXO is a stress-responsive factor, we assayed the effects of either oxidative or metabolic stress responses on modifying the mid mutant phenotype which is characterized by a 50% loss of IOBs within the adult compound eye. While metabolic starvation stress does not affect the mid mutant phenotype, either 1 mM paraquat or 20% coconut oil, oxidative stress inducers, partially suppresses the mid mutant phenotype resulting in a significant recovery of IOBs. Another significant mid-interacting gene we identified is groucho (gro). Mid and Gro are predicted to act as corepressors of the enhancer-of-split gene complex downstream of Notch. Immunolabeling WT and dFOXO null 3(o)L eye-antennal imaginal discs with anti-Mid and anti-Engrailed (En) antibodies indicate that dFOXO is required to activate Mid and En expression within photoreceptor neurons of the eye disc. Taken together, these studies show that Mid and dFOXO serve as critical effectors of cell fate specification and survival within integrated Notch, InR/dAkt, and JNK signaling pathways during 3(o)L and pupal eye imaginal disc development.
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13
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Yuan C, Wang L, Zhou L, Fu Z. The function of FOXO1 in the late phases of the cell cycle is suppressed by PLK1-mediated phosphorylation. Cell Cycle 2014; 13:807-19. [PMID: 24407358 PMCID: PMC3979917 DOI: 10.4161/cc.27727] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Revised: 12/30/2013] [Accepted: 01/03/2014] [Indexed: 12/12/2022] Open
Abstract
Polo-like kinase 1 (PLK1) plays crucial roles in multiple stages of cell division. Our previous studies suggest that global transcriptional regulation by PLK1 may contribute to its multiple functions. PLK1 depletion is associated with a decrease in cell viability and the induction of apoptosis; however, the underlying mechanisms are not completely understood. Here, we report that forkhead box protein O1 (FOXO1) is a novel physiological substrate of PLK1. FOXO1 is at the interface of crucial cellular processes, orchestrating programs of gene expression that regulate apoptosis, cell cycle progression, and oxidative-stress resistance. PLK1 interacts with and phosphorylates FOXO1, mainly at the G 2/M phase of the cell cycle. PLK1-mediated phosphorylation leads to the impairment of FOXO1's transcriptional activity in an Akt-independent manner. By immunofluorescence staining and subcellular fractionation, we demonstrate that PLK1-induced FOXO1 phosphorylation causes its nuclear exclusion. Furthermore, PLK1-mediated phosphorylation of FOXO1 negatively regulates its pro-apoptotic function and abrogates its ability to delay entry into and progression through G 2/M transition. Therefore, our results suggest that PLK1 abrogates the inhibitory effects of FOXO1 on cell growth and survival to ensure timely cell cycle progression. This study not only reveals a novel and major regulatory mechanism of FOXO1 at the late phases of the cell cycle, but also provides new insight into the molecular mechanisms by which PLK1 inhibition leads to growth arrest and cell death.
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Affiliation(s)
- Chengfu Yuan
- Department of Human and Molecular Genetics; VCU Institute of Molecular Genetics; VCU Massey Cancer Center; Virginia Commonwealth University School of Medicine; Richmond, VA USA
| | - Lei Wang
- Department of Human and Molecular Genetics; VCU Institute of Molecular Genetics; VCU Massey Cancer Center; Virginia Commonwealth University School of Medicine; Richmond, VA USA
- Sun Yat-Sen University; Guangzhou, PR China
| | - Liang Zhou
- Department of Human and Molecular Genetics; VCU Institute of Molecular Genetics; VCU Massey Cancer Center; Virginia Commonwealth University School of Medicine; Richmond, VA USA
| | - Zheng Fu
- Department of Human and Molecular Genetics; VCU Institute of Molecular Genetics; VCU Massey Cancer Center; Virginia Commonwealth University School of Medicine; Richmond, VA USA
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14
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Dutriaux A, Godart A, Brachet A, Silber J. The insulin receptor is required for the development of the Drosophila peripheral nervous system. PLoS One 2013; 8:e71857. [PMID: 24069139 PMCID: PMC3772016 DOI: 10.1371/journal.pone.0071857] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 07/09/2013] [Indexed: 01/12/2023] Open
Abstract
The Insulin Receptor (InR) in Drosophila presents features conserved in its mammalian counterparts. InR is required for growth; it is expressed in the central and embryonic nervous system and modulates the time of differentiation of the eye photoreceptor without altering cell fate. We show that the InR is required for the formation of the peripheral nervous system during larval development and more particularly for the formation of sensory organ precursors (SOPs) on the fly notum and scutellum. SOPs arise in the proneural cluster that expresses high levels of the proneural proteins Achaete (Ac) and Scute (Sc). The other cells will become epidermis due to lateral inhibition induced by the Notch (N) receptor signal that prevents its neighbors from adopting a neural fate. In addition, misexpression of the InR or of other components of the pathway (PTEN, Akt, FOXO) induces the development of an abnormal number of macrochaetes that are Drosophila mechanoreceptors. Our data suggest that InR regulates the neural genes ac, sc and sens. The FOXO transcription factor which is localized in the cytoplasm upon insulin uptake, displays strong genetic interaction with the InR and is involved in Ac regulation. The genetic interactions between the epidermal growth factor receptor (EGFR), Ras and InR/FOXO suggest that these proteins cooperate to induce neural gene expression. Moreover, InR/FOXO is probably involved in the lateral inhibition process, since genetic interactions with N are highly significant. These results show that the InR can alter cell fate, independently of its function in cell growth and proliferation.
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Affiliation(s)
- Annie Dutriaux
- University Paris Diderot, Sorbonne Paris Cité, IJM, UMR 7592 CNRS, Paris, France
| | - Aurélie Godart
- University Paris Diderot, Sorbonne Paris Cité, IJM, UMR 7592 CNRS, Paris, France
| | - Anna Brachet
- University Paris Diderot, Sorbonne Paris Cité, IJM, UMR 7592 CNRS, Paris, France
| | - Joël Silber
- University Paris Diderot, Sorbonne Paris Cité, IJM, UMR 7592 CNRS, Paris, France
- * E-mail:
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15
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Chow KT, Timblin GA, McWhirter SM, Schlissel MS. MK5 activates Rag transcription via Foxo1 in developing B cells. ACTA ACUST UNITED AC 2013; 210:1621-34. [PMID: 23878308 PMCID: PMC3727319 DOI: 10.1084/jem.20130498] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The kinase MK5 phosphorylates and activates Foxo1 at serine 215, and this modification is required for Foxo1 to induce Rag transcription. Foxo1 is a critical, direct regulator of Rag (recombination activating gene) transcription during B cell development and is thus essential for the generation of a diverse repertoire of antigen receptors. Although Foxo1 regulation has been widely studied in many cell types, pathways regulating Foxo1 in B cells have not been fully elucidated. By screening a panel of Foxo1 mutants, we identified serine 215 on Foxo1 as a novel phosphorylation site that is essential for the activation of Rag transcription. Mutation of S215 strongly attenuated transactivation of Rag but did not affect most other Foxo1 target genes. We show that MK5, a MAPK-activated protein kinase, is a previously unidentified upstream regulator of Foxo1. MK5 was necessary and sufficient to activate Rag transcription in transformed and primary pro–B cells. Together, our experiments show that MK5 positively regulates Rag transcription via phosphorylation of Foxo1 in developing B cells.
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Affiliation(s)
- Kwan T Chow
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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16
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Zhang W, Hietakangas V, Wee S, Lim SC, Gunaratne J, Cohen SM. ER stress potentiates insulin resistance through PERK-mediated FOXO phosphorylation. Genes Dev 2013; 27:441-9. [PMID: 23431056 DOI: 10.1101/gad.201731.112] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Endoplasmic reticulum (ER) stress is emerging as a potential contributor to the onset of type 2 diabetes by making cells insulin-resistant. However, our understanding of the mechanisms by which ER stress affects insulin response remains fragmentary. Here we present evidence that the ER stress pathway acts via a conserved signaling mechanism involving the protein kinase PERK to modulate cellular insulin responsiveness. Insulin signaling via AKT reduces activity of FOXO transcription factors. In some cells, PERK can promote insulin responsiveness. However, we found that PERK also acts oppositely via phosphorylation of FOXO to promote FOXO activity. Inhibition of PERK improves cellular insulin responsiveness at the level of FOXO activity. We suggest that the protein kinase PERK may be a promising pharmacological target for ameliorating insulin resistance.
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Affiliation(s)
- Wei Zhang
- Institute of Molecular and Cell Biology, Singapore 138673
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17
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Gehret AU, Hinkle PM. siRNA screen identifies the phosphatase acting on the G protein-coupled thyrotropin-releasing hormone receptor. ACS Chem Biol 2013; 8:588-98. [PMID: 23215350 DOI: 10.1021/cb3004513] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
G protein-coupled receptors (GPCRs) are an ubiquitously expressed class of transmembrane proteins involved in the signal transduction of neurotransmitters, hormones and various other ligands. Their signaling output is desensitized by mechanisms involving phosphorylation, internalization, and dissociation from G proteins and resensitized by mechanisms involving dephosphorylation, but details about the phosphatases responsible are generally lacking. We describe here the use of an siRNA-based library to knock down expression of specific phosphatase subunits to identify protein phosphatase 1-α (PP1α) as important for the thyrotropin-releasing hormone (TRH) receptor. Inhibition of PP1α synthesis and overexpression of dominant negative PP1α preserved receptor phosphorylation under conditions favoring dephosphorylation, whereas overexpression of PP1α accelerated dephosphorylation. Knockdown of all three PP1 catalytic subunits inhibited TRH receptor phosphorylation much more powerfully than knockdown of PP1α alone, suggesting that different PP1 isoforms function redundantly. Knockdown of a structural subunit of PP2A, a second potential hit in the library screen, was ineffective. Calyculin A, a potent inhibitor of PP1 family phosphatases, strongly inhibited dephosphorylation of transfected TRH receptors and endogenous receptors in pituitary cells, but fostriecin, which is selective for PP2A family phosphatases, did not. We conclude that the PP1 class of phosphatases is essential for TRH receptor dephosphorylation.
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Affiliation(s)
- Austin U. Gehret
- Department of Science and Mathematics,
National Technical Institute for the Deaf, Rochester Institute of Technology, Rochester, New York 14623,
United States
| | - Patricia M. Hinkle
- Department
of Pharmacology and
Physiology, University of Rochester Medical Center, Rochester, New York 14642, United States
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18
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Sim C, Denlinger DL. Juvenile hormone III suppresses forkhead of transcription factor in the fat body and reduces fat accumulation in the diapausing mosquito, Culex pipiens. INSECT MOLECULAR BIOLOGY 2013; 22:1-11. [PMID: 23121109 DOI: 10.1111/j.1365-2583.2012.01166.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Juvenile hormone (JH) controls diverse physiological and developmental events including diapause and nutrient metabolism. The focal point of endocrine regulation in adult reproductive diapause is initiated by a halt of JH synthesis. In diapausing females of the mosquito Culex pipiens, the other key molecular event is the signalling pathway from insulin to forkhead of transcription factor (FOXO). We hypothesized that a halt of JH synthesis is related to activation of FOXO, which results in increasing lipid reserves in the fat body at the onset of the diapause programme. In this study, the full-length sequence of the foxo gene in C. pipiens was characterized, and the protein abundance pattern of the foxo gene product was analyzed by immunoblotting and immunohistochemistry. FOXO was much more abundant in the fat body of diapausing females than in the fat body of nondiapausing females; much lower levels were present in other adult tissues. When we topically applied JH III to diapause-destined females, FOXO was suppressed, and fat accumulation was reduced, suggesting an interaction between JH synthesis and FOXO that is critical for expression of the diapause phenotype.
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Affiliation(s)
- Cheolho Sim
- Department of Biology, Baylor University, Waco, TX 76798, USA.
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19
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Zanella F, Dos Santos NR, Link W. Moving to the core: spatiotemporal analysis of Forkhead box O (FOXO) and nuclear factor-κB (NF-κB) nuclear translocation. Traffic 2013; 14:247-58. [PMID: 23231504 DOI: 10.1111/tra.12034] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 12/06/2012] [Accepted: 12/10/2012] [Indexed: 12/23/2022]
Abstract
Nuclear translocation of proteins is an essential aspect of normal cell function, and defects in this process have been detected in many disease-associated conditions. The detection and quantification of nuclear translocation was significantly boosted by the association of robotized microscopy with automated image analysis, a technology designated as high-content screening. Image-based high-content screening and analysis provides the means to systematically observe cellular translocation events in time and space in response to chemical or genetic perturbation at large scale. This approach yields powerful insights into the regulation of complex signaling networks independently of preconceived notions of mechanistic relationships. In this review, we briefly overview the different mechanisms involved in nucleocytoplasmic protein trafficking. In addition, we discuss high-content approaches used to interrogate the mechanistic and spatiotemporal dynamics of cellular signaling events using Forkhead box O (FOXO) proteins and the nuclear factor-κB (NF-κB) as important and clinically relevant examples.
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Affiliation(s)
- Fabian Zanella
- School of Medicine, Cardiology Division, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0613, USA
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20
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Zhou W, Chen L, Yang S, Li F, Li X. Behavioral stress-induced activation of FoxO3a in the cerebral cortex of mice. Biol Psychiatry 2012; 71:583-92. [PMID: 21978520 PMCID: PMC3254805 DOI: 10.1016/j.biopsych.2011.08.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 08/22/2011] [Accepted: 08/25/2011] [Indexed: 01/22/2023]
Abstract
BACKGROUND The transcription factor FoxO3a is highly expressed in brain, but little is known about the response of FoxO3a to behavioral stress and its impact in the associated behavioral changes. METHODS We tested the response of brain FoxO3a in the learned helplessness (LH) paradigm and tested signaling pathways that mediate the response of FoxO3a. RESULTS A single session of inescapable shocks (IES) in mice reduced FoxO3a phosphorylation at the Akt-regulating serine/threonine residues and induced prolonged nuclear accumulation of FoxO3a in the cerebral cortex, both indicating activation of FoxO3a in brain. The response of FoxO3a is accompanied by a transient inactivation of Akt and a prolonged activation of glycogen synthase kinase-3beta (GSK3β). Noticeably, FoxO3a formed a protein complex with GSK3β in the cerebral cortex, and the interaction between the two proteins was stronger in IES-treated mice. Inhibition of glycogen synthase kinase-3 was able to abolish IES-induced LH behavior, disrupt IES-induced GSK3β-FoxO3a interaction, and reduce nuclear FoxO3a accumulation. In vitro approaches further revealed that the interaction between GSK3β and FoxO3a was strongest when both were active; FoxO3a was phosphorylated by recombinant GSK3β; and glycogen synthase kinase-3 inhibitors effectively reduced FoxO3a transcriptional activity. Importantly, IES-induced LH behavior was markedly diminished in FoxO3a-deficient mice that had minimal FoxO3a expression and reduced levels of FoxO3a-inducible genes. CONCLUSIONS FoxO3a is activated in response to IES by interacting with GSK3β, and inhibition of GSK3β or reducing FoxO3a expression promotes resistance to stress-induced behavioral disturbance by disrupting this signaling mechanism.
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Affiliation(s)
- Wenjun Zhou
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, 35294, USA
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21
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Yano H, Yamamoto-Hino M, Awano W, Aoki-Kinoshita KF, Tsuda-Sakurai K, Okano H, Goto S. Identification of proteasome components required for apical localization of Chaoptin using functional genomics. J Neurogenet 2012; 26:53-63. [PMID: 22417167 DOI: 10.3109/01677063.2012.661497] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Abstract: the distinct localization of membrane proteins with regard to cell polarity is crucial for the structure and function of various organs in multicellular organisms. However, the molecules and mechanisms that regulate protein localization to particular subcellular domains are still largely unknown. To identify the genes involved in regulation of protein localization, the authors performed a large-scale screen using a Drosophila RNA interference (RNAi) library, by which Drosophila genes could be knocked down in a tissue- and stage-specific manner. Drosophila photoreceptor cells have a morphologically distinct apicobasal polarity, along which Chaoptin (Chp), a glycosylphosphatidylinositol (GPI)-anchored membrane protein, and the Na (+) , K(+) -ATPase are localized to the apical and basolateral domains, respectively. By examining the subcellular localization of these proteins, the authors identified 106 genes whose knockdown resulted in mislocalization of Chp and Na(+) , K(+) -ATPase. Gene ontology analysis revealed that the knockdown of proteasome components resulted in mislocalization of Chp to the basolateral plasma membrane. These results suggest that the proteasome is involved, directly or indirectly, in selective localization of Chp to the apical plasma membrane of Drosophila photoreceptor cells.
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Affiliation(s)
- Hiroyuki Yano
- Research Group of Glycobiology and Glycotechnology , Tokyo , Japan
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22
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Abstract
Drosophila melanogaster has a long history as a model organism with several unique features that make it an ideal research tool for the study of the relationship between genotype and phenotype. Importantly fundamental genetic principles as well as key human disease genes have been uncovered through the use of Drosophila. The contribution of the fruit fly to science and medicine continues in the postgenomic era as cell-based Drosophila RNAi screens are a cost-effective and scalable enabling technology that can be used to quantify the contribution of different genes to diverse cellular processes. Drosophila high-throughput screens can also be used as integral part of systems-level approaches to describe the architecture and dynamics of cellular networks.
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Affiliation(s)
- Chris Bakal
- Dynamical Cell Systems Laboratory, Division of Cancer Biology, The Institute of Cancer Research, London, UK.
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23
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Puig O, Mattila J. Understanding Forkhead box class O function: lessons from Drosophila melanogaster. Antioxid Redox Signal 2011; 14:635-47. [PMID: 20618068 DOI: 10.1089/ars.2010.3407] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Drosophila melanogaster is one of the most widely used model organisms. About 77% of known human disease genes have an ortholog in Drosophila, and many of the cellular signaling pathways are common between fruit flies and mammals. For example, a key signaling pathway in the regulation of growth and metabolism, the insulin/insulin-like growth factor 1 signaling pathway, is well conserved between flies and humans. Downstream effectors of this pathway are the Forkhead box class O (FOXO) family of transcription factors, with four members in mammals and a single FOXO protein in Drosophila, dFOXO. Research in Drosophila has been critical to elucidate the molecular mechanisms by which FOXO transcription factors regulate insulin signaling. In this review, we summarize the studies leading to dFOXO identification and its characterization as a central regulator of metabolism, life span, cell cycle, growth, and stress resistance.
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Affiliation(s)
- Oscar Puig
- Molecular Profiling Research Informatics, Merck Research Laboratories, Rahway, New Jersey 07065, USA.
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24
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Abstract
Transcription factors are the common convergence points of signal transduction pathways to affect gene transcription. Signal transduction activity results in posttranslational modification (PTM) of transcription factors and the sum of these modifications at any given time point will determine the action of the transcription factor. It has been suggested that these PTMs provide a transcription factor code analogous to the histone code. However, the number and variety of these modifications and the lack of knowledge in general of their dynamics precludes at present a concise view of how combinations of PTMs affect transcription factor function. Also, a single type of PTM such as phosphorylation can have opposing effects on transcription factor activity. Transcription factors of the Forkhead box O (FOXO) class are predominantly regulated through signaling, by phosphoinositide 3-kinase/protein kinase B (also known as AKT) pathway and a reactive oxygen species/c-Jun N-terminal kinase pathway. Both pathways result in increased FOXO phosphorylation yet with opposing result. Whereas PKB-mediated phosphorylation inactivates FOXO, c-Jun N-terminal kinase-mediated phosphorylation results in activation of FOXO. Here we discuss regulation of FOXO transcription factors by phosphorylation as an example for understanding integration of signal transduction at the level of transcription activity.
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25
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Shahmoradgoli M, Mannherz O, Engel F, Heck S, Krämer A, Seiffert M, Pscherer A, Lichter P. Antiapoptotic function of charged multivesicular body protein 5: a potentially relevant gene in acute myeloid leukemia. Int J Cancer 2010; 128:2865-71. [PMID: 20734392 DOI: 10.1002/ijc.25632] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Accepted: 08/12/2010] [Indexed: 12/22/2022]
Abstract
In recent years, RNA interference (RNAi) has been widely used to uncover gene function or pathway context of novel genes. In our study, we describe a short-hairpin RNA-based RNAi screening of a set of functionally uncharacterized human genes for their possible capability to inhibit apoptosis. We thereby identified a new antiapoptotic function for CHMP5 (charged multivesicular body protein 5), which was confirmed by overexpression and rescue assays. Furthermore, caspase assays showed that CHMP5 silencing induced caspase cascade activation mainly through extrinsic apoptosis pathway. Based on genome-wide expression array profiling, a possible regulatory role of CHMP5 on apoptosis-associated genes and different signaling pathways including nuclear factor kappa B was revealed. In addition, we found significantly higher CHMP5 mRNA levels in acute myeloid leukemia patients. This observation together with the antiapoptotic feature of CHMP5 suggests a possible oncogenic function for this gene in leukemogenesis.
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Affiliation(s)
- Maria Shahmoradgoli
- Department of Molecular Genetics, German Cancer Research Center, Heidelberg, Germany
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26
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KRIT1 regulates the homeostasis of intracellular reactive oxygen species. PLoS One 2010; 5:e11786. [PMID: 20668652 PMCID: PMC2910502 DOI: 10.1371/journal.pone.0011786] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Accepted: 06/25/2010] [Indexed: 01/06/2023] Open
Abstract
KRIT1 is a gene responsible for Cerebral Cavernous Malformations (CCM), a major cerebrovascular disease characterized by abnormally enlarged and leaky capillaries that predispose to seizures, focal neurological deficits, and fatal intracerebral hemorrhage. Comprehensive analysis of the KRIT1 gene in CCM patients has suggested that KRIT1 functions need to be severely impaired for pathogenesis. However, the molecular and cellular functions of KRIT1 as well as CCM pathogenesis mechanisms are still research challenges. We found that KRIT1 plays an important role in molecular mechanisms involved in the maintenance of the intracellular Reactive Oxygen Species (ROS) homeostasis to prevent oxidative cellular damage. In particular, we demonstrate that KRIT1 loss/down-regulation is associated with a significant increase in intracellular ROS levels. Conversely, ROS levels in KRIT1−/− cells are significantly and dose-dependently reduced after restoration of KRIT1 expression. Moreover, we show that the modulation of intracellular ROS levels by KRIT1 loss/restoration is strictly correlated with the modulation of the expression of the antioxidant protein SOD2 as well as of the transcriptional factor FoxO1, a master regulator of cell responses to oxidative stress and a modulator of SOD2 levels. Furthermore, we show that the KRIT1-dependent maintenance of low ROS levels facilitates the downregulation of cyclin D1 expression required for cell transition from proliferative growth to quiescence. Finally, we demonstrate that the enhanced ROS levels in KRIT1−/− cells are associated with an increased cell susceptibility to oxidative DNA damage and a marked induction of the DNA damage sensor and repair gene Gadd45α, as well as with a decline of mitochondrial energy metabolism. Taken together, our results point to a new model where KRIT1 limits the accumulation of intracellular oxidants and prevents oxidative stress-mediated cellular dysfunction and DNA damage by enhancing the cell capacity to scavenge intracellular ROS through an antioxidant pathway involving FoxO1 and SOD2, thus providing novel and useful insights into the understanding of KRIT1 molecular and cellular functions.
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27
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Abstract
RNA interference (RNAi) is an effective tool for genome-scale, high-throughput analysis of gene function. In the past five years, a number of genome-scale RNAi high-throughput screens (HTSs) have been done in both Drosophila and mammalian cultured cells to study diverse biological processes, including signal transduction, cancer biology, and host cell responses to infection. Results from these screens have led to the identification of new components of these processes and, importantly, have also provided insights into the complexity of biological systems, forcing new and innovative approaches to understanding functional networks in cells. Here, we review the main findings that have emerged from RNAi HTS and discuss technical issues that remain to be improved, in particular the verification of RNAi results and validation of their biological relevance. Furthermore, we discuss the importance of multiplexed and integrated experimental data analysis pipelines to RNAi HTS.
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Affiliation(s)
- Stephanie Mohr
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
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28
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Dick O, Bading H. Synaptic activity and nuclear calcium signaling protect hippocampal neurons from death signal-associated nuclear translocation of FoxO3a induced by extrasynaptic N-methyl-D-aspartate receptors. J Biol Chem 2010; 285:19354-61. [PMID: 20404335 DOI: 10.1074/jbc.m110.127654] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Synaptic activity and the generation of nuclear calcium signals promote neuronal survival through a transcription-dependent process that is not fully understood. Here we show that one mechanism of activity-induced acquired neuroprotection involves the Forkhead transcription factor, FoxO3a, which is known to induce genomic death responses upon translocation from the cytosol to the nucleus. Depletion of endogenous FoxO3a using RNA interference renders hippocampal neurons more resistant to excitotoxic cell death. Using a FoxO3a-green fluorescent protein (GFP) fusion protein to monitor in real time the localization of FoxO3a in hippocampal neurons, we found that several cell death inducing stimuli, including the stimulation of extrasynaptic N-methyl-D-aspartate receptors, growth factor withdrawal, and oxygen-glucose deprivation, caused a swift translocation of FoxO3a-GFP from the cytosol to the cell nucleus. This translocation was inhibited in hippocampal neurons that had undergone prolonged periods of synaptic activity before exposure to cell death-inducing conditions. The activity-dependent protection from death signal-induced FoxO3a-GFP nuclear translocation required synaptic N-methyl-D-aspartate receptor activation and was dependent on nuclear calcium signaling and calcium/calmodulin-dependent protein kinase IV. The modulation of nucleo-cytoplasmic shuttling of FoxO3a may represent one mechanism through which nuclear calcium-induced genomic responses affect cell death processes.
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Affiliation(s)
- Oliver Dick
- Department of Neurobiology, Interdisciplinary Center for Neurosciences IZN, University of Heidelberg, 69120 Heidelberg, Germany
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29
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Narasimhan SD, Mukhopadhyay A, Tissenbaum HA. InAKTivation of insulin/IGF-1 signaling by dephosphorylation. Cell Cycle 2010; 8:3878-84. [PMID: 19901535 DOI: 10.4161/cc.8.23.10072] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Signal transduction pathways are tightly regulated by phosphorylation-dephosphorylation cycles and yet the mammalian genome contains far more genes that encode for protein kinases than protein phosphatases. Therefore, to target specific substrates, many phosphatases associate with distinct regulatory subunits and thereby modulate multiple cellular processes. One such example is the C. elegans PP2A regulatory subunit PPTR-1 that negatively regulates the insulin/insulin-like growth factor signaling pathway to modulate longevity, dauer diapause, fat metabolism and stress resistance. PPTR-1, as well as its mammalian homolog B56beta, specifically target the PP2A enzyme to AKT and mediate the dephosphorylation of this important kinase at a conserved threonine residue. In C. elegans, the major consequence of this modulation is activation of the FOXO transcription factor homolog DAF-16, which in turn regulates transcription of its many target genes involved in longevity and stress resistance. Understanding the function of B56 subunits may have important consequences in diseases such as Type 2 diabetes and cancer where the balance of Akt phosphorylation is deregulated.
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Affiliation(s)
- Sri Devi Narasimhan
- Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, MA, USA
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30
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Mattila J, Puig O. Insights to transcriptional networks by using high throughput RNAi strategies. Brief Funct Genomics 2009; 9:43-52. [PMID: 19952073 DOI: 10.1093/bfgp/elp046] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
RNA interference (RNAi) is a powerful method to unravel the role of a given gene in eukaryotic cells. The development of high throughput assay platforms such as fluorescence plate readers and high throughput microscopy has allowed the design of genome wide RNAi screens to systemically discern members of regulatory networks around various cellular processes. Here we summarize the different strategies employed in RNAi screens to reveal regulators of transcriptional networks. We focus our discussion in experimental approaches designed to uncover regulatory interactions modulating transcription factor activity.
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Affiliation(s)
- Jaakko Mattila
- Merck Research Laboratories, Department of Molecular Profiling-Research Informatics, Rahway, NJ 07065, USA.
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31
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Adding more content to screening: reactivation of FOXO as a therapeutic strategy. Clin Transl Oncol 2009; 11:651-8. [DOI: 10.1007/s12094-009-0420-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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32
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Escribano C, Delgado-Martín C, Rodríguez-Fernández JL. CCR7-Dependent Stimulation of Survival in Dendritic Cells Involves Inhibition of GSK3β. THE JOURNAL OF IMMUNOLOGY 2009; 183:6282-95. [DOI: 10.4049/jimmunol.0804093] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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33
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Drosophila FoxO regulates organism size and stress resistance through an adenylate cyclase. Mol Cell Biol 2009; 29:5357-65. [PMID: 19651894 DOI: 10.1128/mcb.00302-09] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Forkhead box class O (FoxO) transcription factors are a family of conserved proteins that regulate the cellular responses to various stimuli, such as energy deprivation, stress, and developmental cues. FoxO proteins are important mediators of the insulin signaling pathway, adjusting growth and metabolism to nutrient availability. Insulin signaling acts together with the glucagon-stimulated cAMP signaling pathway to orchestrate the organism response to various nutritional conditions. In this study, we demonstrate that Drosophila melanogaster FoxO (dFoxO) regulates cAMP signaling by directly inducing the expression of an adenylate cyclase gene, ac76e. Interestingly, ac76e is expressed in a highly restricted pattern throughout fly development, limited to the corpus allatum (CA), gastric cecum, and malpighian tubules. dFoxO activation of AC76E in the CA increases starvation resistance and limits growth. Our results unravel a new role for dFoxO, integrating cAMP and insulin signaling to adapt organism growth to the existing nutritional conditions.
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Shan G. RNA interference as a gene knockdown technique. Int J Biochem Cell Biol 2009; 42:1243-51. [PMID: 19442757 DOI: 10.1016/j.biocel.2009.04.023] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2009] [Revised: 04/20/2009] [Accepted: 04/29/2009] [Indexed: 01/11/2023]
Abstract
Not many scientific breakthroughs bring significant advances simultaneously in both basic research and translational applications like the discovery of RNA interference. Along with the elucidation of the RNA interference pathway and the discovery of its participation in crucial biological events, a branch of science has grown to utilize the RNA interference pathway as a biotechnology for both basic and applied research. Small interference RNA, plasmid-, and virus-encoded short-hairpin RNA are now regular reagents in the tool box of biologists to knockdown the expression of specific genes posttranscriptionally. Efforts have also been made to develop RNA interference based therapeutics into reality. Many concerns about the RNA interference technique have now been answered through research and development, although hurdles are still present. In this review, the RNA interference/microRNA pathway is briefly introduced followed with a detailed summary about the design and application of the RNA interference experiments, along with examples of the utilization of the RNA interference technology in animal cells and model organisms. Recent progresses and current concerns are also highlighted. Two techniques, namely morpholino and external guide sequence, are discussed as complementary gene knockdown technology. RNA interference technology, along with several other alternative gene knockdown techniques, is now indispensable to modern biological and medical research.
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Affiliation(s)
- Ge Shan
- Department of Molecular, Cellular, and Developmental Biology, Yale University, P. O. Box 208103, New Haven, CT 06520, USA.
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Benayoun BA, Veitia RA. A post-translational modification code for transcription factors: sorting through a sea of signals. Trends Cell Biol 2009; 19:189-97. [PMID: 19328693 DOI: 10.1016/j.tcb.2009.02.003] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Revised: 02/11/2009] [Accepted: 02/19/2009] [Indexed: 11/29/2022]
Abstract
Cellular responses to environmental or physiological cues rely on transduction pathways that must ensure discrimination between different signals. These cascades 'crosstalk' and lead to a combinatorial regulation. This often results in different combinations of post-translational modifications (PTMs) on target proteins, which might act as a molecular barcode. Although appealing, the idea of the existence of such a code for transcription factors is debated. Using general arguments and recent evidence, we propose that a PTM code is not only possible but necessary in the context of transcription factors regulating multiple processes. Thus, the coding potential of PTM combinations should both provide a further layer of information integration from several transduction pathways and warrant highly specific cellular outputs.
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Affiliation(s)
- Bérénice A Benayoun
- Institut Jacques Monod, Bâtiment Buffon, 15 Rue Hélène Brion, Paris Cedex 13, France
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Brosens JJ, Wilson MSC, Lam EWF. FOXO transcription factors: from cell fate decisions to regulation of human female reproduction. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 665:227-41. [PMID: 20429428 DOI: 10.1007/978-1-4419-1599-3_17] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
All key reproductive events in the human ovary and uterus, including follicle activation, ovulation, implantation, decidualization, luteolysis and menstruation, are dependent upon profound tissue remodelling, characterised by cyclical waves of cell proliferation, differentiation, apoptosis, tissue breakdown and regeneration. FOXO transcription factors, an evolutionarily conserved subfamily of the forkhead transcription factors, have emerged as master regulators of cell fate decision capable of integrating avariety of stress, growth factor and cytokine signaling pathways with the transcription machinery. The ability of FOXOs to regulate seemingly opposing cellular responses, ranging from cell cycle arrest and oxidative stress responses to differentiation and apoptosis, renders these transcription factors indispensable for cyclic tissue remodelling in female reproduction. Conversely, perturbations in the expression or activity of FOXO transcription factors are increasingly linked to common reproductive disorders, such as pregnancy loss, endometriosis, endometrial cancer and primary ovarian insufficiency.
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Affiliation(s)
- Jan J Brosens
- Institute of Reproductive and Developmental Biology Imperial College London, Hammersmith Campus, London W12 0NN, UK.
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