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Short CA, Hahn DA. Fat enough for the winter? Does nutritional status affect diapause? JOURNAL OF INSECT PHYSIOLOGY 2023; 145:104488. [PMID: 36717056 DOI: 10.1016/j.jinsphys.2023.104488] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 01/23/2023] [Accepted: 01/25/2023] [Indexed: 06/18/2023]
Abstract
Many insects enter a dormant state termed diapause in anticipation of seasonal inhospitable conditions. Insects drastically reduce their feeding during diapause. Their reduced nutrient intake is paired with substantial nutrient costs: maintaining basal metabolism during diapause, repairing tissues damaged by adverse conditions, and resuming development after diapause. Many investigators have asked "Does nutrition affect diapause?" In this review, we survey the studies that have attempted to address this question. We propose the term nutritional status, a holistic view of nutrition that explicitly includes the perception, intake, and storage of the great breadth of nutrients. We examine the studies that have sought to test if nutrition affects diapause, trying to identify specific facets of nutritional status that affect diapause phenotypes. Curiously, low quality host plants during the diapause induction phase generally induce diapause, but food deprivation during the same phase generally averts diapause. Using the geometric framework of nutrition to identify specific dietary components that affect diapause may reconcile these contrasting findings. This framework can establish nutritionally permissive space, distinguishing nutrient changes that affect diapause from changes that induce other dormancies. Refeeding is another important experimental technique that distinguishes between diapause and quiescence, a non-diapause dormancy. We also find insufficient evidence for the hypothesis that nutrient stores regulate diapause length and suggest manipulations to investigate the role of nutrient stores in diapause termination. Finally, we propose mechanisms that could interface nutritional status with the diapause program, focusing on combined action of the nutritional axis between the gut, fat body, and brain.
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Affiliation(s)
- Clancy A Short
- Department of Entomology and Nematology, The University of Florida, Gainesville, FL, United States.
| | - Daniel A Hahn
- Department of Entomology and Nematology, The University of Florida, Gainesville, FL, United States
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2
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Srinivasan AR, Tran TT, Bonini NM. Loss of miR-34 in Drosophila dysregulates protein translation and protein turnover in the aging brain. Aging Cell 2022; 21:e13559. [PMID: 35166006 PMCID: PMC8920459 DOI: 10.1111/acel.13559] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 12/20/2021] [Accepted: 01/11/2022] [Indexed: 12/27/2022] Open
Abstract
Aging is a risk factor for neurodegenerative disease, but precise mechanisms that influence this relationship are still under investigation. Work in Drosophila melanogaster identified the microRNA miR‐34 as a modifier of aging and neurodegeneration in the brain. MiR‐34 mutants present aspects of early aging, including reduced lifespan, neurodegeneration, and a buildup of the repressive histone mark H3K27me3. To better understand how miR‐34 regulated pathways contribute to age‐associated phenotypes in the brain, here we transcriptionally profiled the miR‐34 mutant brain. This identified that genes associated with translation are dysregulated in the miR‐34 mutant. The brains of these animals show increased translation activity, accumulation of protein aggregation markers, and altered autophagy activity. To determine if altered H3K27me3 was responsible for this proteostasis dysregulation, we studied the effects of increased H3K27me3 by mutating the histone demethylase Utx. Reduced Utx activity enhanced neurodegeneration and mimicked the protein accumulation seen in miR‐34 mutant brains. However, unlike the miR‐34 mutant, Utx mutant brains did not show similar altered autophagy or translation activity, suggesting that additional miR‐34‐targeted pathways are involved. Transcriptional analysis of predicted miR‐34 targets identified Lst8, a subunit of Tor Complex 1 (TORC1), as a potential target. We confirmed that miR‐34 regulates the 3’ UTR of Lst8 and identified several additional predicted miR‐34 targets that may be critical for maintaining proteostasis and brain health. Together, these results present novel understanding of the brain and the role of the conserved miRNA miR‐34 in impacting proteostasis in the brain with age.
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Affiliation(s)
| | - Tracy T. Tran
- Department of Biology University of Pennsylvania Philadelphia Pennsylvania USA
| | - Nancy M. Bonini
- Department of Biology University of Pennsylvania Philadelphia Pennsylvania USA
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3
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Kaldun JC, Sprecher SG. Initiated by CREB: Resolving Gene Regulatory Programs in Learning and Memory. Bioessays 2019; 41:e1900045. [DOI: 10.1002/bies.201900045] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 04/29/2019] [Indexed: 12/29/2022]
Affiliation(s)
- Jenifer C. Kaldun
- Department of BiologyUniversity of Fribourg1700 Fribourg Switzerland
| | - Simon G. Sprecher
- Department of BiologyUniversity of Fribourg1700 Fribourg Switzerland
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4
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Veeran S, Cui G, Shu B, Yi X, Zhong G. Curcumin-induced autophagy and nucleophagy in Spodoptera frugiperda Sf9 insect cells occur via PI3K/AKT/TOR pathways. J Cell Biochem 2019; 120:2119-2137. [PMID: 30242882 DOI: 10.1002/jcb.27520] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 07/30/2018] [Indexed: 01/24/2023]
Abstract
Compounds from plants or microbes are important resources for new natural pesticides against a wide variety of pests. The growing attention on the role of autophagy (type II cell death) in regulation of insect toxicology has propelled researchers to investigate autophagic cell death pathways. Our previous study proved that the cytotoxic effect of curcumin in Spodoptera frugiperda cells is regulated by autophagy. However, the signaling pathways and molecular mechanisms had not been determined. The current study elucidates curcumin inhibition of survival signaling by blocking the activation of PI3K/AKT/TOR pathways to induce autophagy in S. frugiperda cells. The result demonstrates that nucleophagy associated with cell death following the curcumin treatment. Following the curcumin treatment, Atg8/LC3 immunostaining in both nucleus and cytoplasm was markedly increased. Further, messenger RNA expression level of Atg8 and Atg1 genes regulation by curcumin was examined using quantitative reverse transcription polymerase chain reaction, and the result exhibited increased level of expression after curcumin treatment in a time-dependent manner. Our current study provides new insights to the autophagy occurring via PI3K/AKT/TOR pathways in S. frugiperda Sf9 insect cells induced by curcumin. Taken together, our results show for the first time that curcumin induced nucleophagy in lepidopteron insect cell line.
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Affiliation(s)
- Sethuraman Veeran
- Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture, South China Agricultural University, Guangzhou, China.,Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, China
| | - Gaofeng Cui
- Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture, South China Agricultural University, Guangzhou, China.,Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, China
| | - Benshui Shu
- Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture, South China Agricultural University, Guangzhou, China.,Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, China
| | - Xin Yi
- Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture, South China Agricultural University, Guangzhou, China.,Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, China
| | - Guohua Zhong
- Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture, South China Agricultural University, Guangzhou, China.,Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, China
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5
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Wen JK, Wang YT, Chan CC, Hsieh CW, Liao HM, Hung CC, Chen GC. Atg9 antagonizes TOR signaling to regulate intestinal cell growth and epithelial homeostasis in Drosophila. eLife 2017; 6:29338. [PMID: 29144896 PMCID: PMC5690286 DOI: 10.7554/elife.29338] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 10/29/2017] [Indexed: 02/06/2023] Open
Abstract
Autophagy is essential for maintaining cellular homeostasis and survival under various stress conditions. Autophagy-related gene 9 (Atg9) encodes a multipass transmembrane protein thought to act as a membrane carrier for forming autophagosomes. However, the molecular regulation and physiological importance of Atg9 in animal development remain largely unclear. Here, we generated Atg9 null mutant flies and found that loss of Atg9 led to shortened lifespan, locomotor defects, and increased susceptibility to stress. Atg9 loss also resulted in aberrant adult midgut morphology with dramatically enlarged enterocytes. Interestingly, inhibiting the TOR signaling pathway rescued the midgut defects of the Atg9 mutants. In addition, Atg9 interacted with PALS1-associated tight junction protein (Patj), which associates with TSC2 to regulate TOR activity. Depletion of Atg9 caused a marked decrease in TSC2 levels. Our findings revealed an antagonistic relationship between Atg9 and TOR signaling in the regulation of cell growth and tissue homeostasis.
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Affiliation(s)
- Jung-Kun Wen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.,Genome and Systems Biology Program, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Yi-Ting Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.,Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Chih-Chiang Chan
- Graduate Institute of Physiology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Cheng-Wen Hsieh
- Graduate Institute of Physiology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Hsiao-Man Liao
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Chin-Chun Hung
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Guang-Chao Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.,Genome and Systems Biology Program, College of Life Science, National Taiwan University, Taipei, Taiwan.,Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
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6
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Conceptual framework of the eco-physiological phases of insect diapause development justified by transcriptomic profiling. Proc Natl Acad Sci U S A 2017; 114:8532-8537. [PMID: 28720705 DOI: 10.1073/pnas.1707281114] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Insects often overcome unfavorable seasons in a hormonally regulated state of diapause during which their activity ceases, development is arrested, metabolic rate is suppressed, and tolerance of environmental stress is bolstered. Diapausing insects pass through a stereotypic succession of eco-physiological phases termed "diapause development." The phasing is varied in the literature, and the whole concept is sometimes criticized as being too artificial. Here we present the results of transcriptional profiling using custom microarrays representing 1,042 genes in the drosophilid fly, Chymomyza costata Fully grown, third-instar larvae programmed for diapause by a photoperiodic (short-day) signal were assayed as they traversed the diapause developmental program. When analyzing the gradual dynamics in the transcriptomic profile, we could readily distinguish distinct diapause developmental phases associated with induction/initiation, maintenance, cold acclimation, and termination by cold or by photoperiodic signal. Accordingly, each phase is characterized by a specific pattern of gene expression, supporting the physiological relevance of the concept of diapause phasing. Further, we have dissected in greater detail the changes in transcript levels of elements of several signaling pathways considered critical for diapause regulation. The phase of diapause termination is associated with enhanced transcript levels in several positive elements stimulating direct development (the 20-hydroxyecdysone pathway: Ecr, Shd, Broad; the Wnt pathway: basket, c-jun) that are countered by up-regulation in some negative elements (the insulin-signaling pathway: Ilp8, PI3k, Akt; the target of rapamycin pathway: Tsc2 and 4EBP; the Wnt pathway: shaggy). We speculate such up-regulations may represent the early steps linked to termination of diapause programming.
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7
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Shao X, Lai D, Zhang L, Xu H. Induction of Autophagy and Apoptosis via PI3K/AKT/TOR Pathways by Azadirachtin A in Spodoptera litura Cells. Sci Rep 2016; 6:35482. [PMID: 27752103 PMCID: PMC5067515 DOI: 10.1038/srep35482] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Accepted: 09/13/2016] [Indexed: 12/09/2022] Open
Abstract
Azadirachtin is one of the most effective botanical insecticides and has been widely used in pest control. Toxicological reports show that azadirachtin can induce apoptosis in various insect cell lines. However, studies of azadirachtin-induced autophagy in cultured insect cells are lacking. This study reports that azadirachtin A significantly inhibits cell proliferation by inducing autophagic and apoptotic cell death in Spodoptera litura cultured cell line (SL-1 cell). Characteristic autophagolysosome and Atg8-PE (phosphatidylethanolamine) accumulation were observed by electron microscopy and western blotting, indicating that azadirachtin triggered autophagy in SL-1 cell. Furthermore, azadirachtin inhibited survival signaling by blocking the activation of PI3K, AKT and the down-stream target of rapamycin. Similar to the positive control of starvation, azadirachtin induced the activation of insulin receptor (InR) via a cellular feedback mechanism. In addition, the autophagy-related 5 (Atg5), a molecular switch of autophagy and apoptosis, was truncated (tAtg5) to trigger cytochrome c release into the cytoplasm under azadirachtin stress, which indicated that azadirachtin induced apoptosis through autophagy. Our findings suggest that azadirachtin primarily induced autophagy in SL-1 cell by dysregulating InR- and PI3K/AKT/TOR pathways, then stimulated apoptosis by activating tAtg5.
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Affiliation(s)
- Xuehua Shao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Key Laboratory of Natural Pesticide and Chemical Biology of the Ministry of Education, South China Agricultural University, Guangzhou 510642, China
| | - Duo Lai
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Key Laboratory of Natural Pesticide and Chemical Biology of the Ministry of Education, South China Agricultural University, Guangzhou 510642, China
- Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
| | - Ling Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Key Laboratory of Natural Pesticide and Chemical Biology of the Ministry of Education, South China Agricultural University, Guangzhou 510642, China
- College of Life Science and Technology, Jinan University, Guangzhou 510642, China
| | - Hanhong Xu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Key Laboratory of Natural Pesticide and Chemical Biology of the Ministry of Education, South China Agricultural University, Guangzhou 510642, China
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8
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Booth DG, Takagi M, Sanchez-Pulido L, Petfalski E, Vargiu G, Samejima K, Imamoto N, Ponting CP, Tollervey D, Earnshaw WC, Vagnarelli P. Ki-67 is a PP1-interacting protein that organises the mitotic chromosome periphery. eLife 2014; 3:e01641. [PMID: 24867636 PMCID: PMC4032110 DOI: 10.7554/elife.01641] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Accepted: 04/27/2014] [Indexed: 12/23/2022] Open
Abstract
When the nucleolus disassembles during open mitosis, many nucleolar proteins and RNAs associate with chromosomes, establishing a perichromosomal compartment coating the chromosome periphery. At present nothing is known about the function of this poorly characterised compartment. In this study, we report that the nucleolar protein Ki-67 is required for the assembly of the perichromosomal compartment in human cells. Ki-67 is a cell-cycle regulated protein phosphatase 1-binding protein that is involved in phospho-regulation of the nucleolar protein B23/nucleophosmin. Following siRNA depletion of Ki-67, NIFK, B23, nucleolin, and four novel chromosome periphery proteins all fail to associate with the periphery of human chromosomes. Correlative light and electron microscopy (CLEM) images suggest a near-complete loss of the entire perichromosomal compartment. Mitotic chromosome condensation and intrinsic structure appear normal in the absence of the perichromosomal compartment but significant differences in nucleolar reassembly and nuclear organisation are observed in post-mitotic cells.DOI: http://dx.doi.org/10.7554/eLife.01641.001.
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Affiliation(s)
- Daniel G Booth
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Masatoshi Takagi
- Cellular Dynamics Laboratory, Riken Advanced Science Institute, Wako Saitama, Japan
| | - Luis Sanchez-Pulido
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Elizabeth Petfalski
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Giulia Vargiu
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Kumiko Samejima
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Naoko Imamoto
- Cellular Dynamics Laboratory, Riken Advanced Science Institute, Wako Saitama, Japan
| | - Chris P Ponting
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - William C Earnshaw
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
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9
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Koyama T, Mendes CC, Mirth CK. Mechanisms regulating nutrition-dependent developmental plasticity through organ-specific effects in insects. Front Physiol 2013; 4:263. [PMID: 24133450 PMCID: PMC3783933 DOI: 10.3389/fphys.2013.00263] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 09/06/2013] [Indexed: 12/25/2022] Open
Abstract
Nutrition, via the insulin/insulin-like growth factor (IIS)/Target of Rapamycin (TOR) signaling pathway, can provide a strong molding force for determining animal size and shape. For instance, nutrition induces a disproportionate increase in the size of male horns in dung and rhinoceros beetles, or mandibles in staghorn or horned flour beetles, relative to body size. In these species, well-fed male larvae produce adults with greatly enlarged horns or mandibles, whereas males that are starved or poorly fed as larvae bear much more modest appendages. Changes in IIS/TOR signaling plays a key role in appendage development by regulating growth in the horn and mandible primordia. In contrast, changes in the IIS/TOR pathway produce minimal effects on the size of other adult structures, such as the male genitalia in fruit flies and dung beetles. The horn, mandible and genitalia illustrate that although all tissues are exposed to the same hormonal environment within the larval body, the extent to which insulin can induce growth is organ specific. In addition, the IIS/TOR pathway affects body size and shape by controlling production of metamorphic hormones important for regulating developmental timing, like the steroid molting hormone ecdysone and sesquiterpenoid hormone juvenile hormone. In this review, we discuss recent results from Drosophila and other insects that highlight mechanisms allowing tissues to differ in their sensitivity to IIS/TOR and the potential consequences of these differences on body size and shape.
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Affiliation(s)
- Takashi Koyama
- Development, Evolution and the Environment Laboratory, Instituto Gulbenkian de Ciência Oeiras, Portugal
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10
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Narasimhan M, Rathinam M, Riar A, Patel D, Mummidi S, Yang HS, Colburn NH, Henderson GI, Mahimainathan L. Programmed cell death 4 (PDCD4): a novel player in ethanol-mediated suppression of protein translation in primary cortical neurons and developing cerebral cortex. Alcohol Clin Exp Res 2012; 37:96-109. [PMID: 22757755 DOI: 10.1111/j.1530-0277.2012.01850.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Accepted: 04/03/2012] [Indexed: 01/25/2023]
Abstract
BACKGROUND Prenatal exposure to ethanol (EtOH) elicits a range of neuro-developmental abnormalities, microcephaly to behavioral deficits. Impaired protein synthesis has been connected to pathogenesis of EtOH-induced brain damage and abnormal neuron development. However, mechanisms underlying these impairments of protein synthesis are not known. In this study, we illustrate the effects of EtOH on programmed cell death protein 4 (PDCD4), a tumor and translation repressor. METHODS Primary cortical neurons (PCNs) were treated with 2.5 and 4 mg/ml EtOH for different time points (4 to 24 hours), and PDCD4 expression was detected by Western blotting. Protein synthesis was determined using [(35) S] methionine incorporation assay. Methyl cap pull-down assay was performed to establish the effect of EtOH on association of eukaryotic initiation factor 4A (eIF4A) with capped mRNA. Luciferase assay was performed to determine the in vivo translation. A 2-day acute 5-dose binge model with EtOH (4 g/kg body wt, 25% v/v) was performed in Sprague-Dawley rats at 12-hour intervals and analyzed for PDCD4, eIF4A, and eIF4A-methyl cap association. RESULTS EtOH increased PDCD4 expression in a time- and dose-dependent manner in PCNs, which inhibited the association of eIF4A with methyl cap. EtOH and ectopic PDCD4 expression suppressed in vivo translation in PCNs and RNAi targeting of PDCD4 blocked the inhibitory effect of EtOH on protein synthesis. In utero exposure of pregnant rats to EtOH resulted in a significant increase in PDCD4 in fetal cerebral cortex along with the inhibition of methyl cap-associated eIF4A, compared with isocaloric controls. Increased PDCD4 also occurred in pooled fractions of remaining brain regions. CONCLUSIONS Our data, for the first time, illustrate that PDCD4 mediates inhibitory effects of EtOH on protein synthesis in PCNs and developing brain.
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Affiliation(s)
- Madhusudhanan Narasimhan
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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11
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Age-specific variation in immune response in Drosophila melanogaster has a genetic basis. Genetics 2012; 191:989-1002. [PMID: 22554890 DOI: 10.1534/genetics.112.140640] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Immunosenescence, the age-related decline in immune system function, is a general hallmark of aging. While much is known about the cellular and physiological changes that accompany immunosenescence, we know little about the genetic influences on this phenomenon. In this study we combined age-specific measurements of bacterial clearance ability following infection with whole-genome measurements of the transcriptional response to infection and wounding to identify genes that contribute to the natural variation in immunosenescence, using Drosophila melanogaster as a model system. Twenty inbred lines derived from nature were measured for their ability to clear an Escherichia coli infection at 1 and 4 weeks of age. We used microarrays to simultaneously determine genome-wide expression profiles in infected and wounded flies at each age for 12 of these lines. Lines exhibited significant genetically based variation in bacterial clearance at both ages; however, the genetic basis of this variation changed dramatically with age. Variation in gene expression was significantly correlated with bacterial clearance ability only in the older age group. At 4 weeks of age variation in the expression of 247 genes following infection was associated with genetic variation in bacterial clearance. Functional annotation analyses implicate genes involved in energy metabolism including those in the insulin signaling/TOR pathway as having significant associations with bacterial clearance in older individuals. Given the evolutionary conservation of the genes involved in energy metabolism, our results could have important implications for understanding immunosenescence in other organisms, including humans.
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12
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Bracho-Valdés I, Moreno-Alvarez P, Valencia-Martínez I, Robles-Molina E, Chávez-Vargas L, Vázquez-Prado J. mTORC1- and mTORC2-interacting proteins keep their multifunctional partners focused. IUBMB Life 2011; 63:896-914. [PMID: 21905202 DOI: 10.1002/iub.558] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 07/14/2011] [Indexed: 12/11/2022]
Abstract
The mammalian target of rapamycin, best known as mTOR, is a phylogenetically conserved serine/threonine kinase that controls life-defining cellular processes such as growth, metabolism, survival, and migration under the influence of multiple interacting proteins. Historically, the cellular activities blocked by rapamycin in mammalian cells were considered the only events controlled by mTOR. However, this paradigm changed with the discovery of two signaling complexes differentially sensitive to rapamycin, whose catalytic component is mTOR. The one sensitive to rapamycin, known as mTORC1, promotes protein synthesis in response to growth factors and nutrients via the phosphorylation of p70S6K and 4EBP1; while the other, known as mTORC2, promotes cell migration and survival via the activation of Rho GTPases and the phosphorylation of AKT, respectively. Although mTORC2 kinase activity is not inhibited by rapamycin, hours of incubation with this antibiotic can impede the assembly of this signaling complex. The direct mechanism by which mTORC2 leads to cell migration depends on its interaction with P-Rex1, a Rac-specific guanine nucleotide exchange factor, while additional indirect pathways involve the intervention of PKC or AKT, multifunctional ubiquitous serine/threonine kinases that activate effectors of cell migration upon being phosphorylated by mTORC2 in response to chemotactic signals. These mTORC2 effectors are altered in metastatic cancer. Numerous clinical trials are testing mTOR inhibitors as potential antineoplasic drugs. Here, we briefly review the actions of mTOR with emphasis on the controlling role of mTORC1 and mTORC2-interacting proteins and highlight the mechanisms linked to cell migration.
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Affiliation(s)
- Ismael Bracho-Valdés
- Department of Pharmacology, CINVESTAV-IPN, Av. Instituto Politécnico Nacional 2508.Col. San Pedro Zacatenco, 07000 México D.F., México
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Rybina OY, Zaitsev AA, Roschina NV, Pasyukova EG. Neuroendocrine system in lifespan control of Drosophila melanogaster. ADVANCES IN GERONTOLOGY 2011. [DOI: 10.1134/s207905701103012x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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14
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LaFever L, Feoktistov A, Hsu HJ, Drummond-Barbosa D. Specific roles of Target of rapamycin in the control of stem cells and their progeny in the Drosophila ovary. Development 2010; 137:2117-26. [PMID: 20504961 PMCID: PMC2882131 DOI: 10.1242/dev.050351] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/26/2010] [Indexed: 12/21/2022]
Abstract
Stem cells depend on intrinsic and local factors to maintain their identity and activity, but they also sense and respond to changing external conditions. We previously showed that germline stem cells (GSCs) and follicle stem cells (FSCs) in the Drosophila ovary respond to diet via insulin signals. Insulin signals directly modulate the GSC cell cycle at the G2 phase, but additional unknown dietary mediators control both G1 and G2. Target of rapamycin, or TOR, is part of a highly conserved nutrient-sensing pathway affecting growth, proliferation, survival and fertility. Here, we show that optimal TOR activity maintains GSCs but does not play a major role in FSC maintenance, suggesting differential regulation of GSCs versus FSCs. TOR promotes GSC proliferation via G2 but independently of insulin signaling, and TOR is required for the proliferation, growth and survival of differentiating germ cells. We also report that TOR controls the proliferation of FSCs but not of their differentiating progeny. Instead, TOR controls follicle cell number by promoting survival, independently of either the apoptotic or autophagic pathways. These results uncover specific TOR functions in the control of stem cells versus their differentiating progeny, and reveal parallels between Drosophila and mammalian follicle growth.
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Affiliation(s)
- Leesa LaFever
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Biochemistry and Molecular Biology, Division of Reproductive Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Alexander Feoktistov
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Hwei-Jan Hsu
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Biochemistry and Molecular Biology, Division of Reproductive Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Daniela Drummond-Barbosa
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Biochemistry and Molecular Biology, Division of Reproductive Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
- Department of Environmental Health Sciences, Division of Reproductive Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
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Lee MJ, Feliers D, Mariappan MM, Sataranatarajan K, Mahimainathan L, Musi N, Foretz M, Viollet B, Weinberg JM, Choudhury GG, Kasinath BS. A role for AMP-activated protein kinase in diabetes-induced renal hypertrophy. Am J Physiol Renal Physiol 2006; 292:F617-27. [PMID: 17018841 DOI: 10.1152/ajprenal.00278.2006] [Citation(s) in RCA: 234] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We tested the hypothesis that AMP-activated protein kinase (AMPK), an energy sensor, regulates diabetes-induced renal hypertrophy. In kidney glomerular epithelial cells, high glucose (30 mM), but not equimolar mannitol, stimulated de novo protein synthesis and induced hypertrophy in association with increased phosphorylation of eukaryotic initiation factor 4E binding protein 1 and decreased phosphorylation of eukaryotic elongation factor 2, regulatory events in mRNA translation. These high-glucose-induced changes in protein synthesis were phosphatidylinositol 3-kinase, Akt, and mammalian target of rapamycin (mTOR) dependent and transforming growth factor-beta independent. High glucose reduced AMPK alpha-subunit theronine (Thr) 172 phosphorylation, which required Akt activation. Changes in AMP and ATP content could not fully account for high-glucose-induced reductions in AMPK phosphorylation. Metformin and 5-aminoimidazole-4-carboxamide-1beta-riboside (AICAR) increased AMPK phosphorylation, inhibited high-glucose stimulation of protein synthesis, and prevented high-glucose-induced changes in phosphorylation of 4E binding protein 1 and eukaryotic elongation factor 2. Expression of kinase-inactive AMPK further increased high-glucose-induced protein synthesis. Renal hypertrophy in rats with Type 1 diabetes was associated with reduction in AMPK phosphorylation and increased mTOR activity. In diabetic rats, metformin and AICAR increased renal AMPK phosphorylation, reversed mTOR activation, and inhibited renal hypertrophy, without affecting hyperglycemia. AMPK is a newly identified regulator of renal hypertrophy in diabetes.
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Affiliation(s)
- Myung-Ja Lee
- Dept. of Nephrology, University of Texas Health Science Center, San Antonio, TX 78229, USA
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Mariappan MM, Senthil D, Natarajan KS, Choudhury GG, Kasinath BS. Phospholipase Cγ-Erk Axis in Vascular Endothelial Growth Factor-induced Eukaryotic Initiation Factor 4E Phosphorylation and Protein Synthesis in Renal Epithelial Cells. J Biol Chem 2005; 280:28402-11. [PMID: 15919658 DOI: 10.1074/jbc.m504861200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vascular endothelial growth factor (VEGF) increases protein synthesis and induces hypertrophy in renal tubular epithelial cells (Senthil, D., Choudhury, G. G., McLaurin, C., and Kasinath, B. S. (2003) Kidney Int. 64, 468-479). We examined the role of Erk1/2 MAP kinase in protein synthesis induced by VEGF. VEGF stimulated Erk phosphorylation that was required for induction of protein synthesis. VEGF-induced Erk activation was not dependent on phosphoinositide (PI) 3-kinase activation but required sequential phosphorylation of type 2 VEGF receptor, PLCgamma and c-Src, as demonstrated by inhibitors SU1498, U73122, and PP1, respectively. c-Src phosphorylation was inhibited by U73122, indicating it was downstream of phospholipase (PL)Cgamma. Studies with PP1/2 showed that phosphorylation of c-Src was required for tyrosine phosphorylation of Raf-1, an upstream regulator of Erk. VEGF also stimulated phosphorylation of Pyk-2; VEGF-induced phosphorylation of Pyk2, c-Src and Raf-1 could be abolished by BAPTA/AM, demonstrating requirement for induction of intracellular calcium currents. We examined the downstream events following the phosphorylation of Erk. VEGF stimulated phosphorylation of Mnk1 and eIF4E and induced Mnk1 to shift from the cytoplasm to the nucleus upon phosphorylation. VEGF-induced phosphorylation of Mnk1 and eIF4E required phosphorylation of PLCgamma, c-Src, and Erk. Expression of dominant negative Mnk1 abrogated eIF4E phosphorylation and protein synthesis induced by VEGF. VEGF-stimulated protein synthesis could be blocked by inhibition of PLCgamma by a chemical inhibitor or expression of a dominant negative construct. Our data demonstrate that VEGF-stimulated protein synthesis is Erk-dependent and requires the activation of VEGF receptor 2, PLCgamma, c-Src, Raf, and Erk pathway. VEGF also stimulates Erk-dependent phosphorylation of Mnk1 and eIF4E, crucial events in the initiation phase of protein translation.
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Affiliation(s)
- Meenalakshmi M Mariappan
- O'Brien Kidney Research Center, Department of Medicine, University of Texas Health Science Center, South Texas Veterans Healthcare System, Geriatric Research, Education, and, Clinical Center, San Antonio, Texas 78229, USA
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Rusten TE, Lindmo K, Juhász G, Sass M, Seglen PO, Brech A, Stenmark H. Programmed Autophagy in the Drosophila Fat Body Is Induced by Ecdysone through Regulation of the PI3K Pathway. Dev Cell 2004; 7:179-92. [PMID: 15296715 DOI: 10.1016/j.devcel.2004.07.005] [Citation(s) in RCA: 366] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2004] [Revised: 06/30/2004] [Accepted: 07/06/2004] [Indexed: 10/26/2022]
Abstract
Eukaryotic cells catabolize their own cytoplasm by autophagy in response to amino acid starvation and inductive signals during programmed tissue remodeling and cell death. The Tor and PI3K signaling pathways have been shown to negatively control autophagy in eukaryotes, but the mechanisms that link these effectors to overall animal development and nutritional status in multicellular organisms remain poorly understood. Here, we reveal a complex regulation of programmed and starvation-induced autophagy in the Drosophila fat body. Gain-of-function genetic analysis indicated that ecdysone receptor signaling induces programmed autophagy whereas PI3K signaling represses programmed autophagy. Genetic interaction studies showed that ecdysone signaling downregulates PI3K signaling and that this represents the effector mechanism for induction of programmed autophagy. Hence, these studies link hormonal induction of autophagy to the regulatory function of the PI3K signaling pathway in vivo.
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Affiliation(s)
- Tor Erik Rusten
- Department of Biochemistry, The Norwegian Radium Hospital, Montebello, N-0310 Oslo
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Roy G, Miron M, Khaleghpour K, Lasko P, Sonenberg N. The Drosophila poly(A) binding protein-interacting protein, dPaip2, is a novel effector of cell growth. Mol Cell Biol 2004; 24:1143-54. [PMID: 14729960 PMCID: PMC321445 DOI: 10.1128/mcb.24.3.1143-1154.2004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The 3' poly(A) tail of eukaryotic mRNAs and the poly(A) binding protein (PABP) play important roles in the regulation of translation. Recently, a human PABP-interacting protein, Paip2, which disrupts the PABP-poly(A) interaction and consequently inhibits translation, was described. To gain insight into the biological role of Paip2, we studied the Drosophila melanogaster Paip2 (dPaip2). dPaip2 is the bona fide human Paip2 homologue, as it interacts with dPABP, inhibits binding of dPABP to the mRNA poly(A) tail, and reduces translation of a reporter mRNA by approximately 80% in an S2 cell-free translation extract. Ectopic overexpression of dPaip2 in Drosophila wings and wing discs results in a size reduction phenotype, which is due to a decrease in cell number. Clones of cells overexpressing dPaip2 in wing discs also contain fewer cells than controls. This phenotype can be explained by a primary effect on cell growth. Indeed, overexpression of dPaip2 in postreplicative tissues inhibits growth, inasmuch as it reduces ommatidia size in eyes and cell size in the larval fat body. We conclude that dPaip2 inhibits cell growth primarily by inhibiting protein synthesis.
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Affiliation(s)
- Guylaine Roy
- Department of Biochemistry and McGill Cancer Centre, McGill University, Montréal, Québec H3G 1Y6, Canada
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Senthil D, Choudhury GG, McLaurin C, Kasinath BS. Vascular endothelial growth factor induces protein synthesis in renal epithelial cells: a potential role in diabetic nephropathy. Kidney Int 2003; 64:468-79. [PMID: 12846742 DOI: 10.1046/j.1523-1755.2003.00135.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Vascular endothelial growth factor (VEGF) is an important determinant of ocular complications of diabetes. Its potential role in diabetic renal disease has not been extensively studied. METHODS We employed mice with streptozotocin-induced type 1 diabetes and db/db mice with type 2 diabetes to study the regulation of renal VEGF. Studies of VEGF regulation of protein synthesis were performed using proximal tubular epithelial (MCT) cells in culture. RESULTS A nearly three-fold increase of VEGF165 expression in the renal cortex was seen, coinciding with renal hypertrophy in mice with either type 1 or type 2 diabetes. VEGF increased de novo protein synthesis and induced significant hypertrophy in MCT cells. VEGF stimulation of protein synthesis was dependent on tyrosine phosphorylation of the type 2 VEGF receptor and phosphatidylinositol 3-kinase (PI 3-kinase) activity. Activity of Akt was increased two- to three-fold by VEGF. Expression of dominant-negative Akt showed that Akt activation was also needed for VEGF-induced protein synthesis and cell hypertrophy. As PI 3-kinase-Akt axis regulates initial events in protein translation, these events were examined in the context of VEGF regulation of protein synthesis. VEGF stimulated eukaryotic initiation factor 4E-binding protein (4E-BP1) phosphorylation, which was dependent on activation of PI 3-kinase and Akt. Stable transfection with 4E-BP1 Thr37,46-Ala37,46 mutant abolished the VEGF-induced de novo protein synthesis and cell hypertrophy. CONCLUSION VEGF augments protein synthesis and induces hypertrophy in MCT cells in a PI 3-kinase- and Akt-dependent manner. Phosphorylation of Thr37,46 in 4E-BP1 is required for VEGF-induced protein synthesis and hypertrophy in MCT cells. These data suggest a role for VEGF in the pathogenesis of diabetic renal disease.
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Affiliation(s)
- Duraisamy Senthil
- South Texas Veterans' Health Care System and Department of Medicine, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA
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Barcelo H, Stewart MJ. Altering Drosophila S6 kinase activity is consistent with a role for S6 kinase in growth. Genesis 2002; 34:83-5. [PMID: 12324955 DOI: 10.1002/gene.10132] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Hélène Barcelo
- Department of Biological Sciences, North Dakota State University, Fargo, North Dakota 58105, USA
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