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Wang M, Yang N, Guo W, Yang Y, Bao B, Zhang X, Zhang D. RNAi-mediated glucose transporter 4 (Glut4) silencing inhibits ovarian development and enhances deltamethrin-treated energy depletion in Locusta migratoria. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2024; 203:106014. [PMID: 39084805 DOI: 10.1016/j.pestbp.2024.106014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 06/22/2024] [Accepted: 07/02/2024] [Indexed: 08/02/2024]
Abstract
Energy metabolism is essential for insect development, reproduction and detoxification. Insects often reallocate energy and resources to manage external stress, balancing the demands of detoxification and reproduction. Glucose transport 4 (Glut4), a glucose transporter, is involved in glucose and lipid metabolism. However, the specific molecular mechanism of Glut4 in insect reproduction, and its role in the response to insecticide-induced oxidative stress remain unclear. In this study, LmGlut4 was identified and analyzed in Locusta migratoria. Silencing of LmGlut4 significantly reduced vitellogenin (Vg) biosynthesis in the fat body and Vg absorption by oocytes, ultimately hindering ovarian development and oocyte maturation. Knockdown of LmGlut4 also inhibited the biosynthesis of key insect hormones, such as juvenile hormone (JH), 20-hydroxyecdysone (20E) and insulin. Furthermore, LmGlut4 knockdown led to reduced triglyceride (TG) and glycogen content in the fat body and ovary, as well as decreased capacity for trehalose biosynthesis in adipocytes. Additionally, dsLmGlut4-treated locusts showed heightened sensitivity to deltamethrin, leading to increased triglyceride depletion during detoxification. This study sheds light on the biological function of LmGlut4 in the ovary and provides potential target genes for exploring biological pest management strategies.
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Affiliation(s)
- Mingjun Wang
- Key Laboratory of Zoological Systematics and Application of Hebei Province, Institute of Life Sciences and Green Development, College of Life Sciences, Hebei University, Baoding 071002, China
| | - Ningxin Yang
- Key Laboratory of Zoological Systematics and Application of Hebei Province, Institute of Life Sciences and Green Development, College of Life Sciences, Hebei University, Baoding 071002, China
| | - Wenhui Guo
- Key Laboratory of Zoological Systematics and Application of Hebei Province, Institute of Life Sciences and Green Development, College of Life Sciences, Hebei University, Baoding 071002, China
| | - Yong Yang
- Key Laboratory of Zoological Systematics and Application of Hebei Province, Institute of Life Sciences and Green Development, College of Life Sciences, Hebei University, Baoding 071002, China
| | - Bowen Bao
- Key Laboratory of Zoological Systematics and Application of Hebei Province, Institute of Life Sciences and Green Development, College of Life Sciences, Hebei University, Baoding 071002, China
| | - Xiaohong Zhang
- Key Laboratory of Zoological Systematics and Application of Hebei Province, Institute of Life Sciences and Green Development, College of Life Sciences, Hebei University, Baoding 071002, China.
| | - Daochuan Zhang
- Key Laboratory of Zoological Systematics and Application of Hebei Province, Institute of Life Sciences and Green Development, College of Life Sciences, Hebei University, Baoding 071002, China; Hebei Basic Science Center for Biotic Interaction, Hebei University, Baoding 071002, China.
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2
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Rabah Y, Francés R, Minatchy J, Guédon L, Desnous C, Plaçais PY, Preat T. Glycolysis-derived alanine from glia fuels neuronal mitochondria for memory in Drosophila. Nat Metab 2023; 5:2002-2019. [PMID: 37932430 PMCID: PMC10663161 DOI: 10.1038/s42255-023-00910-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 09/20/2023] [Indexed: 11/08/2023]
Abstract
Glucose is the primary source of energy for the brain; however, it remains controversial whether, upon neuronal activation, glucose is primarily used by neurons for ATP production or if it is partially oxidized in astrocytes, as proposed by the astrocyte-neuron lactate shuttle model for glutamatergic neurons. Thus, an in vivo picture of glucose metabolism during cognitive processes is missing. Here, we uncover in Drosophila melanogaster a glia-to-neuron alanine transfer involving alanine aminotransferase that sustains memory formation. Following associative conditioning, glycolysis in glial cells produces alanine, which is back-converted into pyruvate in cholinergic neurons of the olfactory memory center to uphold their increased mitochondrial needs. Alanine, as a mediator of glia-neuron coupling, could be an alternative to lactate in cholinergic systems. In parallel, a dedicated glial glucose transporter imports glucose specifically for long-term memory, by directly transferring it to neurons for use by the pentose phosphate pathway. Our results demonstrate in vivo the compartmentalization of glucose metabolism between neurons and glial cells during memory formation.
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Affiliation(s)
- Yasmine Rabah
- Energy & Memory, Brain Plasticity Unit, CNRS, ESPCI Paris, PSL Research University, Paris, France
| | - Raquel Francés
- Energy & Memory, Brain Plasticity Unit, CNRS, ESPCI Paris, PSL Research University, Paris, France
| | - Julia Minatchy
- Energy & Memory, Brain Plasticity Unit, CNRS, ESPCI Paris, PSL Research University, Paris, France
| | - Laura Guédon
- Energy & Memory, Brain Plasticity Unit, CNRS, ESPCI Paris, PSL Research University, Paris, France
| | - Coraline Desnous
- Energy & Memory, Brain Plasticity Unit, CNRS, ESPCI Paris, PSL Research University, Paris, France
| | - Pierre-Yves Plaçais
- Energy & Memory, Brain Plasticity Unit, CNRS, ESPCI Paris, PSL Research University, Paris, France.
| | - Thomas Preat
- Energy & Memory, Brain Plasticity Unit, CNRS, ESPCI Paris, PSL Research University, Paris, France.
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3
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Ugrankar-Banerjee R, Tran S, Bowerman J, Kovalenko A, Paul B, Henne WM. The fat body cortical actin network regulates Drosophila inter-organ nutrient trafficking, signaling, and adipose cell size. eLife 2023; 12:e81170. [PMID: 37144872 PMCID: PMC10202455 DOI: 10.7554/elife.81170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 04/25/2023] [Indexed: 05/06/2023] Open
Abstract
Defective nutrient storage and adipocyte enlargement (hypertrophy) are emerging features of metabolic syndrome and type 2 diabetes. Within adipose tissues, how the cytoskeletal network contributes to adipose cell size, nutrient uptake, fat storage, and signaling remain poorly understood. Utilizing the Drosophila larval fat body (FB) as a model adipose tissue, we show that a specific actin isoform-Act5C-forms the cortical actin network necessary to expand adipocyte cell size for biomass storage in development. Additionally, we uncover a non-canonical role for the cortical actin cytoskeleton in inter-organ lipid trafficking. We find Act5C localizes to the FB cell surface and cell-cell boundaries, where it intimately contacts peripheral LDs (pLDs), forming a cortical actin network for cell architectural support. FB-specific loss of Act5C perturbs FB triglyceride (TG) storage and LD morphology, resulting in developmentally delayed larvae that fail to develop into flies. Utilizing temporal RNAi-depletion approaches, we reveal that Act5C is indispensable post-embryogenesis during larval feeding as FB cells expand and store fat. Act5C-deficient FBs fail to grow, leading to lipodystrophic larvae unable to accrue sufficient biomass for complete metamorphosis. In line with this, Act5C-deficient larvae display blunted insulin signaling and reduced feeding. Mechanistically, we also show this diminished signaling correlates with decreased lipophorin (Lpp) lipoprotein-mediated lipid trafficking, and find Act5C is required for Lpp secretion from the FB for lipid transport. Collectively, we propose that the Act5C-dependent cortical actin network of Drosophila adipose tissue is required for adipose tissue size-expansion and organismal energy homeostasis in development, and plays an essential role in inter-organ nutrient transport and signaling.
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Affiliation(s)
| | - Son Tran
- Department of Cell Biology, UT Southwestern Medical CenterDallasUnited States
| | - Jade Bowerman
- Department of Cell Biology, UT Southwestern Medical CenterDallasUnited States
| | | | - Blessy Paul
- Department of Cell Biology, UT Southwestern Medical CenterDallasUnited States
| | - W Mike Henne
- Department of Cell Biology, UT Southwestern Medical CenterDallasUnited States
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4
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Ollinger N, Neuhauser C, Schwarzinger B, Wallner M, Schwarzinger C, Blank‐Landeshammer B, Hager R, Sadova N, Drotarova I, Mathmann K, Karamouzi E, Panopoulos P, Rimbach G, Lüersen K, Weghuber J, Röhrl C. Anti-Hyperglycemic Effects of Oils and Extracts Derived from Sea Buckthorn - A Comprehensive Analysis Utilizing In Vitro and In Vivo Models. Mol Nutr Food Res 2022; 66:e2101133. [PMID: 35426970 PMCID: PMC9285508 DOI: 10.1002/mnfr.202101133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 03/14/2022] [Indexed: 12/15/2022]
Abstract
SCOPE Sea buckthorn (Hippophaes rhamnoides) is capable of ameliorating disturbed glucose metabolism in animal models and human subjects. Here, the effect of sea buckthorn oil as well as of extracts of fruits, leaves, and press cake on postprandial glucose metabolism is systematically investigated. METHODS AND RESULTS Sea buckthorn did neither exert decisive effects in an in vitro model of intestinal glucose absorption nor did it alter insulin secretion. However, sea buckthorn stimulates GLUT4 translocation to the plasma membrane comparable to insulin, indicative of increased glucose clearance from the circulation. Isorhamnetin is identified in all sea buckthorn samples investigated and is biologically active in triggering GLUT4 cell surface localization. Consistently, sea buckthorn products lower circulating glucose by ≈10% in a chick embryo model. Moreover, sea buckthorn products fully revert hyperglycemia in the nematode Caenorhabditis elegans while they are ineffective in Drosophila melanogaster under euglycemic conditions. CONCLUSION These data indicate that edible sea buckthorn products as well as by-products are promising resources for hypoglycemic nutrient supplements that increase cellular glucose clearance into target tissues.
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Affiliation(s)
- Nicole Ollinger
- FFoQSI – Austrian Competence Centre for Feed and Food QualitySafety & InnovationFFoQSI GmbHTechnopark 1DTulln3430Austria
| | - Cathrina Neuhauser
- University of Applied Sciences Upper AustriaStelzhamerstrasse 23Wels4600Austria
| | - Bettina Schwarzinger
- FFoQSI – Austrian Competence Centre for Feed and Food QualitySafety & InnovationFFoQSI GmbHTechnopark 1DTulln3430Austria
- University of Applied Sciences Upper AustriaStelzhamerstrasse 23Wels4600Austria
| | - Melanie Wallner
- FFoQSI – Austrian Competence Centre for Feed and Food QualitySafety & InnovationFFoQSI GmbHTechnopark 1DTulln3430Austria
| | - Clemens Schwarzinger
- Johannes Kepler UniversityInstitute for Chemical Technology of Organic MaterialsLinz4040Austria
| | - Bernhard Blank‐Landeshammer
- FFoQSI – Austrian Competence Centre for Feed and Food QualitySafety & InnovationFFoQSI GmbHTechnopark 1DTulln3430Austria
| | - Roland Hager
- University of Applied Sciences Upper AustriaStelzhamerstrasse 23Wels4600Austria
| | - Nadiia Sadova
- University of Applied Sciences Upper AustriaStelzhamerstrasse 23Wels4600Austria
| | - Ivana Drotarova
- University of Applied Sciences Upper AustriaStelzhamerstrasse 23Wels4600Austria
| | - Katrin Mathmann
- University of Applied Sciences Upper AustriaStelzhamerstrasse 23Wels4600Austria
| | - Eugenia Karamouzi
- European Research & Development Rezos Brands196 New National Road Patras‐AthensPatras26443Greece
| | - Panagiotis Panopoulos
- European Research & Development Rezos Brands196 New National Road Patras‐AthensPatras26443Greece
| | - Gerald Rimbach
- Institute of Human Nutrition and Food ScienceUniversity of KielHermann‐Rodewald‐Strasse 6Kiel24118Germany
| | - Kai Lüersen
- Institute of Human Nutrition and Food ScienceUniversity of KielHermann‐Rodewald‐Strasse 6Kiel24118Germany
| | - Julian Weghuber
- FFoQSI – Austrian Competence Centre for Feed and Food QualitySafety & InnovationFFoQSI GmbHTechnopark 1DTulln3430Austria
- University of Applied Sciences Upper AustriaStelzhamerstrasse 23Wels4600Austria
| | - Clemens Röhrl
- University of Applied Sciences Upper AustriaStelzhamerstrasse 23Wels4600Austria
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5
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Liguori F, Mascolo E, Vernì F. The Genetics of Diabetes: What We Can Learn from Drosophila. Int J Mol Sci 2021; 22:ijms222011295. [PMID: 34681954 PMCID: PMC8541427 DOI: 10.3390/ijms222011295] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/12/2021] [Accepted: 10/16/2021] [Indexed: 12/14/2022] Open
Abstract
Diabetes mellitus is a heterogeneous disease characterized by hyperglycemia due to impaired insulin secretion and/or action. All diabetes types have a strong genetic component. The most frequent forms, type 1 diabetes (T1D), type 2 diabetes (T2D) and gestational diabetes mellitus (GDM), are multifactorial syndromes associated with several genes’ effects together with environmental factors. Conversely, rare forms, neonatal diabetes mellitus (NDM) and maturity onset diabetes of the young (MODY), are caused by mutations in single genes. Large scale genome screenings led to the identification of hundreds of putative causative genes for multigenic diabetes, but all the loci identified so far explain only a small proportion of heritability. Nevertheless, several recent studies allowed not only the identification of some genes as causative, but also as putative targets of new drugs. Although monogenic forms of diabetes are the most suited to perform a precision approach and allow an accurate diagnosis, at least 80% of all monogenic cases remain still undiagnosed. The knowledge acquired so far addresses the future work towards a study more focused on the identification of diabetes causal variants; this aim will be reached only by combining expertise from different areas. In this perspective, model organism research is crucial. This review traces an overview of the genetics of diabetes and mainly focuses on Drosophila as a model system, describing how flies can contribute to diabetes knowledge advancement.
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Affiliation(s)
- Francesco Liguori
- Preclinical Neuroscience, IRCCS Santa Lucia Foundation, 00143 Rome, Italy;
| | - Elisa Mascolo
- Department of Biology and Biotechnology “Charles Darwin”, Sapienza University, 00185 Rome, Italy;
| | - Fiammetta Vernì
- Department of Biology and Biotechnology “Charles Darwin”, Sapienza University, 00185 Rome, Italy;
- Correspondence:
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6
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Glial glucose fuels the neuronal pentose phosphate pathway for long-term memory. Cell Rep 2021; 36:109620. [PMID: 34433052 PMCID: PMC8411112 DOI: 10.1016/j.celrep.2021.109620] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 07/22/2021] [Accepted: 08/05/2021] [Indexed: 01/10/2023] Open
Abstract
Brain function relies almost solely on glucose as an energy substrate. The main model of brain metabolism proposes that glucose is taken up and converted into lactate by astrocytes to fuel the energy-demanding neuronal activity underlying plasticity and memory. Whether direct neuronal glucose uptake is required for memory formation remains elusive. We uncover, in Drosophila, a mechanism of glucose shuttling to neurons from cortex glia, an exclusively perisomatic glial subtype, upon formation of olfactory long-term memory (LTM). In vivo imaging reveals that, downstream of cholinergic activation of cortex glia, autocrine insulin signaling increases glucose concentration in glia. Glucose is then transferred from glia to the neuronal somata in the olfactory memory center to fuel the pentose phosphate pathway and allow LTM formation. In contrast, our results indicate that the increase in neuronal glucose metabolism, although crucial for LTM formation, is not routed to glycolysis. Neuronal glucose metabolism is increased upon long-term memory formation Glial cells shuttle glucose to neurons following insulin signaling activation Glucose fuels the neuronal pentose phosphate pathway
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7
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Ramond E, Dudzic JP, Lemaitre B. Comparative RNA-Seq analyses of Drosophila plasmatocytes reveal gene specific signatures in response to clean injury and septic injury. PLoS One 2020; 15:e0235294. [PMID: 32598400 PMCID: PMC7323993 DOI: 10.1371/journal.pone.0235294] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 06/11/2020] [Indexed: 12/27/2022] Open
Abstract
Drosophila melanogaster's blood cells (hemocytes) play essential roles in wound healing and are involved in clearing microbial infections. Here, we report the transcriptional changes of larval plasmatocytes after clean injury or infection with the Gram-negative bacterium Escherichia coli or the Gram-positive bacterium Staphylococcus aureus compared to hemocytes recovered from unchallenged larvae via RNA-Sequencing. This study reveals 676 differentially expressed genes (DEGs) in hemocytes from clean injury samples compared to unchallenged samples, and 235 and 184 DEGs in E. coli and S. aureus samples respectively compared to clean injury samples. The clean injury samples showed enriched DEGs for immunity, clotting, cytoskeleton, cell migration, hemocyte differentiation, and indicated a metabolic reprogramming to aerobic glycolysis, a well-defined metabolic adaptation observed in mammalian macrophages. Microbial infections trigger significant transcription of immune genes, with significant differences between the E. coli and S. aureus samples suggesting that hemocytes have the ability to engage various programs upon infection. Collectively, our data bring new insights on Drosophila hemocyte function and open the route to post-genomic functional analysis of the cellular immune response.
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Affiliation(s)
- Elodie Ramond
- Global Health Institute, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Jan Paul Dudzic
- Global Health Institute, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Bruno Lemaitre
- Global Health Institute, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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8
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Gupta HP, Jha RR, Ahmad H, Patel DK, Ravi Ram K. Xenobiotic mediated diabetogenesis: Developmental exposure to dichlorvos or atrazine leads to type 1 or type 2 diabetes in Drosophila. Free Radic Biol Med 2019; 141:461-474. [PMID: 31319158 DOI: 10.1016/j.freeradbiomed.2019.07.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 07/14/2019] [Accepted: 07/14/2019] [Indexed: 12/18/2022]
Abstract
The increased incidence of diabetes to the magnitude of a global epidemic is attributed to non-traditional risk factors, including exposure to environmental chemicals. However, the contribution of xenobiotic exposure during the development of an organism to the etiology of diabetes is not fully addressed. Developing stages are more susceptible to chemical insult, but knowledge on the consequence of the same to the onset of diabetes is residual. In this context, by using Drosophila melanogaster having conserved Insulin/Insulin growth factor-like signaling (IIS) as well as glucose homeostasis as a model, we evaluated the potential of developmental exposure to dichlorvos (DDVP, an organophosphorus pesticide) or atrazine (herbicide) to cause diabetes in exposed organisms. Flies exposed to DDVP during their development display insulin deficiency or type 1 diabetes (T1D) while those exposed to atrazine show insulin resistance or type 2 diabetes (T2D), suggesting that exposure to these xenobiotics during organismal development can result in diabetes and that different mechanisms underlie pesticide mediated diabetes. We show that oxidative stress-mediated c-Jun N-terminal kinase (JNK) signaling activation underlies insulin resistance in flies exposed to atrazine during their development while DDVP-mediated T1D involves activation of caspase-mediated cell death pathway. Mitigation of oxidative stress through over-expression of SOD2 in atrazine (20μg/ml) exposed flies, revealed significantly decreased oxidative stress levels and reduced phosphorylation of JNK. Moreover, glucose and Akt phosphorylation levels in SOD2 over-expression flies exposed to atrazine were comparable to those in controls, suggesting restoration in insulin sensitivity. Therefore, exposure to xenobiotics during development is a common risk factor for the development of type 1 or type 2 diabetes. Accordingly, the present study cautions against the use of such diabetogenic pesticides. Also, mitigation of oxidative stress or anti-oxidant supplementation could be a potential therapy for xenobiotic mediated type 2 diabetes.
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Affiliation(s)
- Himanshu Pawankumar Gupta
- Embryotoxicology Laboratory, Environmental Toxicology Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhavan, 31, Mahatma Gandhi Marg, Lucknow, 226 001, Uttar Pradesh, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002, India
| | - Rakesh Roshan Jha
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002, India; Analytical Chemistry Laboratory, Regulatory Toxicology Group, CSIR-Indian Institute of Toxicology Research, Lucknow, 226001, Uttar Pradesh, India
| | - Humaira Ahmad
- Embryotoxicology Laboratory, Environmental Toxicology Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhavan, 31, Mahatma Gandhi Marg, Lucknow, 226 001, Uttar Pradesh, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002, India
| | - Devendra Kumar Patel
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002, India; Analytical Chemistry Laboratory, Regulatory Toxicology Group, CSIR-Indian Institute of Toxicology Research, Lucknow, 226001, Uttar Pradesh, India
| | - Kristipati Ravi Ram
- Embryotoxicology Laboratory, Environmental Toxicology Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhavan, 31, Mahatma Gandhi Marg, Lucknow, 226 001, Uttar Pradesh, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002, India.
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9
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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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10
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Abstract
Despite the importance of insulin signaling pathways in human disease, initial concerns that insect physiology and sugar metabolism differ enough from humans that flies would not model human disease hampered research in this area. However, during the past 10-15 years, evidence has accumulated that flies can indeed model various aspects of diabetes and related human disorders. This cluster of diseases impact insulin and insulin signaling pathways, fields which have been discussed in many excellent review articles in recent years. In this chapter, we restrict our focus to specific examples of diabetes-related disease models in Drosophila, discussing the advantages and limitations of these models in light of physiological similarities and differences between insects and mammals. We discuss features of metabolism and sugar regulation that are shared between flies and mammals, and specific Drosophila models for Type 1 and Type 2 diabetes, Metabolic syndrome, and related abnormalities including insulin resistance and heart disease. We conclude that fly models for diabetes and related disorders enhance our ability to identify genes and discern functional interactions that can be exploited for disease intervention.
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Affiliation(s)
- P Graham
- University of Maryland, College Park, MD, United States
| | - L Pick
- University of Maryland, College Park, MD, United States.
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11
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Silencing a sugar transporter gene reduces growth and fecundity in the brown planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae). Sci Rep 2015; 5:12194. [PMID: 26185058 PMCID: PMC4505327 DOI: 10.1038/srep12194] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 06/08/2015] [Indexed: 11/23/2022] Open
Abstract
The brown planthopper (BPH), Nilaparvata lugens, sugar transporter gene 6 (Nlst6) is a facilitative glucose/fructose transporter (often called a passive carrier) expressed in midgut that mediates sugar transport from the midgut lumen to hemolymph. The influence of down regulating expression of sugar transporter genes on insect growth, development, and fecundity is unknown. Nonetheless, it is reasonable to suspect that transporter-mediated uptake of dietary sugar is essential to the biology of phloem-feeding insects. Based on this reasoning, we posed the hypothesis that silencing, or reducing expression, of a BPH sugar transporter gene would be deleterious to the insects. To test our hypothesis, we examined the effects of Nlst6 knockdown on BPH biology. Reducing expression of Nlst6 led to profound effects on BPHs. It significantly prolonged the pre-oviposition period, shortened the oviposition period, decreased the number of eggs deposited and reduced body weight, compared to controls. Nlst6 knockdown also significantly decreased fat body and ovarian (particularly vitellogenin) protein content as well as vitellogenin gene expression. Experimental BPHs accumulated less fat body glucose compared to controls. We infer that Nlst6 acts in BPH growth and fecundity, and has potential as a novel target gene for control of phloem-feeding pest insects.
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12
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Kim J, Neufeld TP. Dietary sugar promotes systemic TOR activation in Drosophila through AKH-dependent selective secretion of Dilp3. Nat Commun 2015; 6:6846. [PMID: 25882208 PMCID: PMC4402654 DOI: 10.1038/ncomms7846] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 03/04/2015] [Indexed: 12/23/2022] Open
Abstract
Secreted ligands of the insulin family promote cell growth and maintain sugar homeostasis. Insulin release is tightly regulated in response to dietary conditions, but how insulin producing cells (IPCs) coordinate their responses to distinct nutrient signals is unclear. Here, we show that regulation of insulin secretion in Drosophila larvae has been segregated into distinct branches: whereas amino acids promote secretion of Drosophila insulin-like peptide 2 (Dilp2), circulating sugars promote selective release of Dilp3. Dilp3 is uniquely required for sugar-mediated activation of TOR signaling and suppression of autophagy in the larval fat body. Sugar levels are not sensed directly by the IPCs, but rather by the adipokinetic hormone (AKH)-producing cells of the corpora cardiaca, and we demonstrate that AKH signaling is required in the IPCs for sugar-dependent Dilp3 release. Thus, IPCs integrate multiple cues to regulate secretion of distinct insulin subtypes under varying nutrient conditions.
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Affiliation(s)
- Jung Kim
- Department of Genetics, Cell Biology and Development, University of Minnesota, 6-160 Jackson Hall, 321 Church St SE, Minneapolis, Minnesota 55455, USA
| | - Thomas P Neufeld
- Department of Genetics, Cell Biology and Development, University of Minnesota, 6-160 Jackson Hall, 321 Church St SE, Minneapolis, Minnesota 55455, USA
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13
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Lizunov VA, Stenkula KG, Blank PS, Troy A, Lee JP, Skarulis MC, Cushman SW, Zimmerberg J. Human adipose cells in vitro are either refractory or responsive to insulin, reflecting host metabolic state. PLoS One 2015; 10:e0119291. [PMID: 25768970 PMCID: PMC4359092 DOI: 10.1371/journal.pone.0119291] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 01/12/2015] [Indexed: 01/14/2023] Open
Abstract
While intercellular communication processes are frequently characterized by switch-like transitions, the endocrine system, including the adipose tissue response to insulin, has been characterized by graded responses. Yet here individual cells from adipose tissue biopsies are best described by a switch-like transition between the basal and insulin-stimulated states for the trafficking of the glucose transporter GLUT4. Two statistically-defined populations best describe the observed cellular heterogeneity, representing the fractions of refractive and responsive adipose cells. Furthermore, subjects exhibiting high systemic insulin sensitivity indices (SI) have high fractions of responsive adipose cells in vitro, while subjects exhibiting decreasing SI have increasing fractions of refractory cells in vitro. Thus, a two-component model best describes the relationship between cellular refractory fraction and subject SI. Since isolated cells exhibit these different response characteristics in the presence of constant culture conditions and milieu, we suggest that a physiological switching mechanism at the adipose cellular level ultimately drives systemic SI.
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Affiliation(s)
- Vladimir A. Lizunov
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States of America
| | - Karin G. Stenkula
- Experimental Diabetes, Metabolism, and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States of America
- Experimental Medical Sciences, Lund University, Lund, Sweden
| | - Paul S. Blank
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States of America
| | - Aaron Troy
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States of America
| | - Jo-Ping Lee
- Experimental Diabetes, Metabolism, and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States of America
| | - Monica C. Skarulis
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States of America
| | - Samuel W. Cushman
- Experimental Diabetes, Metabolism, and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States of America
| | - Joshua Zimmerberg
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States of America
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