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Brown EB, Klok J, Keene AC. Measuring metabolic rate in single flies during sleep and waking states via indirect calorimetry. J Neurosci Methods 2022; 376:109606. [PMID: 35483506 PMCID: PMC9310448 DOI: 10.1016/j.jneumeth.2022.109606] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 04/13/2022] [Accepted: 04/18/2022] [Indexed: 11/23/2022]
Abstract
BACKGROUND Drosophila melanogaster is a leading genetic model for studying the neural regulation of sleep. Sleep is associated with changes in behavior and physiological state that are largely conserved across species. The investigation of sleep in flies has predominantly focused on behavioral readouts of sleep because physiological measurements, including changes in brain activity and metabolic rate, are less accessible. We have previously used stop-flow indirect calorimetry to measure whole body metabolic rate in single flies and have shown that in flies, like mammals, metabolic rate is reduced during sleep. NEW METHOD Here, we describe a modified version of this system that allows for efficient and highly sensitive acquisition of CO2 output from single flies. RESULTS In this modified system, we show that sleep-dependent changes in metabolic rate are diminished in aging flies, supporting the notion that sleep quality is reduced as flies age. We also describe a modification that allows for simultaneous acquisition of CO2 and O2 levels, providing a respiratory quotient that quantifies how metabolic stores are utilized. We find that the respiratory quotient identified in flies on an all-sugar diet is suggestive of lipogenesis, where the dietary sugar provided to the flies is being converted to fat. COMPARISON WITH EXISTING METHODS AND CONCLUSIONS Taken together, the measurement of metabolic rate via indirect calorimetry not only provides a physiological readout of sleep depth, but also provides insight the metabolic regulation of nutrient utilization, with broad applications to genetic studies in flies.
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Affiliation(s)
- Elizabeth B Brown
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Jaco Klok
- Sable Systems International, Las Vegas, NV 89032, USA
| | - Alex C Keene
- Department of Biology, Texas A&M University, College Station, TX 77843, USA.
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2
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Krycer JR, Lor M, Fitzsimmons RL, Hudson JE. A cell culture platform for quantifying metabolic substrate oxidation in bicarbonate-buffered medium. J Biol Chem 2021; 298:101547. [PMID: 34971704 PMCID: PMC8819040 DOI: 10.1016/j.jbc.2021.101547] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/21/2021] [Accepted: 12/23/2021] [Indexed: 12/21/2022] Open
Abstract
Complex diseases such as cancer and diabetes are underpinned by changes in metabolism, specifically by which and how nutrients are catabolized. Substrate utilization can be directly examined by measuring a metabolic endpoint rather than an intermediate (such as tricarboxylic cycle metabolite). For instance, oxidation of specific substrates can be measured in vitro by incubation of live cultures with substrates containing radiolabeled carbon and measuring radiolabeled carbon dioxide. To increase throughput, we previously developed a miniaturized platform to measure substrate oxidation of both adherent and suspension cells using multiwell plates rather than flasks. This enabled multiple conditions to be examined simultaneously, ideal for drug screens and mechanistic studies. However, like many metabolic assays, this was not compatible with bicarbonate-buffered media, which is susceptible to alkalinization upon exposure to gas containing little carbon dioxide such as air. While other buffers such as HEPES can overcome this problem, bicarbonate has additional biological roles as a metabolic substrate and in modulating hormone signaling. Here, we create a bicarbonate-buffered well-plate platform to measure substrate oxidation. This was achieved by introducing a sealed environment within each well that was equilibrated with carbon dioxide, enabling bicarbonate buffering. As proof of principle, we assessed metabolic flux in cultured adipocytes, demonstrating that bicarbonate-buffered medium increased lipogenesis, glucose oxidation, and sensitivity to insulin in comparison to HEPES-buffered medium. This convenient and high-throughput method facilitates the study and screening of metabolic activity under more physiological conditions to aid biomedical research.
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Affiliation(s)
- James R Krycer
- QIMR Berghofer Medical Research Institute; School of Biomedical Sciences, Faculty of Health, Queensland University of Technology
| | - Mary Lor
- QIMR Berghofer Medical Research Institute
| | | | - James E Hudson
- QIMR Berghofer Medical Research Institute; School of Biomedical Sciences, Faculty of Health, Queensland University of Technology; School of Biomedical Sciences, Faculty of Medicine, The University of Queensland.
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3
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Francis D, Ghazanfar S, Havula E, Krycer JR, Strbenac D, Senior A, Minard AY, Geddes T, Nelson ME, Weiss F, Stöckli J, Yang JYH, James DE. Genome-wide analysis in Drosophila reveals diet-by-gene interactions and uncovers diet-responsive genes. G3-GENES GENOMES GENETICS 2021; 11:6287063. [PMID: 34568906 PMCID: PMC8496270 DOI: 10.1093/g3journal/jkab171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 05/08/2021] [Indexed: 11/26/2022]
Abstract
Genetic and environmental factors play a major role in metabolic health. However, they do not act in isolation, as a change in an environmental factor such as diet may exert different effects based on an individual’s genotype. Here, we sought to understand how such gene–diet interactions influenced nutrient storage and utilization, a major determinant of metabolic disease. We subjected 178 inbred strains from the Drosophila genetic reference panel (DGRP) to diets varying in sugar, fat, and protein. We assessed starvation resistance, a holistic phenotype of nutrient storage and utilization that can be robustly measured. Diet influenced the starvation resistance of most strains, but the effect varied markedly between strains such that some displayed better survival on a high carbohydrate diet (HCD) compared to a high-fat diet while others had opposing responses, illustrating a considerable gene × diet interaction. This demonstrates that genetics plays a major role in diet responses. Furthermore, heritability analysis revealed that the greatest genetic variability arose from diets either high in sugar or high in protein. To uncover the genetic variants that contribute to the heterogeneity in starvation resistance, we mapped 566 diet-responsive SNPs in 293 genes, 174 of which have human orthologs. Using whole-body knockdown, we identified two genes that were required for glucose tolerance, storage, and utilization. Strikingly, flies in which the expression of one of these genes, CG4607 a putative homolog of a mammalian glucose transporter, was reduced at the whole-body level, displayed lethality on a HCD. This study provides evidence that there is a strong interplay between diet and genetics in governing survival in response to starvation, a surrogate measure of nutrient storage efficiency and obesity. It is likely that a similar principle applies to higher organisms thus supporting the case for nutrigenomics as an important health strategy.
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Affiliation(s)
- Deanne Francis
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Shila Ghazanfar
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia.,School of Mathematics and Statistics, The University of Sydney, Sydney, NSW 2006, Australia
| | - Essi Havula
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - James R Krycer
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Dario Strbenac
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia.,School of Mathematics and Statistics, The University of Sydney, Sydney, NSW 2006, Australia
| | - Alistair Senior
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Annabel Y Minard
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Thomas Geddes
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Marin E Nelson
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Fiona Weiss
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Jacqueline Stöckli
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Jean Y H Yang
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia.,School of Mathematics and Statistics, The University of Sydney, Sydney, NSW 2006, Australia
| | - David E James
- Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia.,School of Medical Sciences, The University of Sydney, Sydney, NSW 2006, Australia
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4
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Krycer JR, Quek LE, Francis D, Zadoorian A, Weiss FC, Cooke KC, Nelson ME, Diaz-Vegas A, Humphrey SJ, Scalzo R, Hirayama A, Ikeda S, Shoji F, Suzuki K, Huynh K, Giles C, Varney B, Nagarajan SR, Hoy AJ, Soga T, Meikle PJ, Cooney GJ, Fazakerley DJ, James DE. Insulin signaling requires glucose to promote lipid anabolism in adipocytes. J Biol Chem 2020; 295:13250-13266. [PMID: 32723868 DOI: 10.1074/jbc.ra120.014907] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/14/2020] [Indexed: 12/12/2022] Open
Abstract
Adipose tissue is essential for metabolic homeostasis, balancing lipid storage and mobilization based on nutritional status. This is coordinated by insulin, which triggers kinase signaling cascades to modulate numerous metabolic proteins, leading to increased glucose uptake and anabolic processes like lipogenesis. Given recent evidence that glucose is dispensable for adipocyte respiration, we sought to test whether glucose is necessary for insulin-stimulated anabolism. Examining lipogenesis in cultured adipocytes, glucose was essential for insulin to stimulate the synthesis of fatty acids and glyceride-glycerol. Importantly, glucose was dispensable for lipogenesis in the absence of insulin, suggesting that distinct carbon sources are used with or without insulin. Metabolic tracing studies revealed that glucose was required for insulin to stimulate pathways providing carbon substrate, NADPH, and glycerol 3-phosphate for lipid synthesis and storage. Glucose also displaced leucine as a lipogenic substrate and was necessary to suppress fatty acid oxidation. Together, glucose provided substrates and metabolic control for insulin to promote lipogenesis in adipocytes. This contrasted with the suppression of lipolysis by insulin signaling, which occurred independently of glucose. Given previous observations that signal transduction acts primarily before glucose uptake in adipocytes, these data are consistent with a model whereby insulin initially utilizes protein phosphorylation to stimulate lipid anabolism, which is sustained by subsequent glucose metabolism. Consequently, lipid abundance was sensitive to glucose availability, both during adipogenesis and in Drosophila flies in vivo Together, these data highlight the importance of glucose metabolism to support insulin action, providing a complementary regulatory mechanism to signal transduction to stimulate adipose anabolism.
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Affiliation(s)
- James R Krycer
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia; Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia
| | - Lake-Ee Quek
- Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia; School of Mathematics and Statistics, University of Sydney, Sydney, New South Wales, Australia
| | - Deanne Francis
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia; Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia
| | - Armella Zadoorian
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia; Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia
| | - Fiona C Weiss
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia; Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia
| | - Kristen C Cooke
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia; Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia
| | - Marin E Nelson
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia; Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia
| | - Alexis Diaz-Vegas
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia; Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia
| | - Sean J Humphrey
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia; Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia
| | - Richard Scalzo
- Faculty of Engineering and Information Technologies, University of Sydney, Sydney, New South Wales, Australia
| | - Akiyoshi Hirayama
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, Japan; AMED-CREST, Japan Agency for Medical Research and Development (AMED), Otemachi, Chiyoda-Ku, Tokyo, Japan
| | - Satsuki Ikeda
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, Japan
| | - Futaba Shoji
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, Japan
| | - Kumi Suzuki
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, Japan
| | - Kevin Huynh
- Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Corey Giles
- Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Bianca Varney
- Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Shilpa R Nagarajan
- Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Andrew J Hoy
- Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Tomoyoshi Soga
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, Japan; AMED-CREST, Japan Agency for Medical Research and Development (AMED), Otemachi, Chiyoda-Ku, Tokyo, Japan
| | - Peter J Meikle
- Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Gregory J Cooney
- Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Daniel J Fazakerley
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia; Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia
| | - David E James
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia; Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.
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5
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Krycer JR, Quek LE, Francis D, Fazakerley DJ, Elkington SD, Diaz-Vegas A, Cooke KC, Weiss FC, Duan X, Kurdyukov S, Zhou PX, Tambar UK, Hirayama A, Ikeda S, Kamei Y, Soga T, Cooney GJ, James DE. Lactate production is a prioritized feature of adipocyte metabolism. J Biol Chem 2020; 295:83-98. [PMID: 31690627 PMCID: PMC6952601 DOI: 10.1074/jbc.ra119.011178] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 10/31/2019] [Indexed: 12/14/2022] Open
Abstract
Adipose tissue is essential for whole-body glucose homeostasis, with a primary role in lipid storage. It has been previously observed that lactate production is also an important metabolic feature of adipocytes, but its relationship to adipose and whole-body glucose disposal remains unclear. Therefore, using a combination of metabolic labeling techniques, here we closely examined lactate production of cultured and primary mammalian adipocytes. Insulin treatment increased glucose uptake and conversion to lactate, with the latter responding more to insulin than did other metabolic fates of glucose. However, lactate production did not just serve as a mechanism to dispose of excess glucose, because we also observed that lactate production in adipocytes did not solely depend on glucose availability and even occurred independently of glucose metabolism. This suggests that lactate production is prioritized in adipocytes. Furthermore, knocking down lactate dehydrogenase specifically in the fat body of Drosophila flies lowered circulating lactate and improved whole-body glucose disposal. These results emphasize that lactate production is an additional metabolic role of adipose tissue beyond lipid storage and release.
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Affiliation(s)
- James R Krycer
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Lake-Ee Quek
- Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia; School of Mathematics and Statistics, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Deanne Francis
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Daniel J Fazakerley
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia; Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, CB2 0QQ, United Kingdom
| | - Sarah D Elkington
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Alexis Diaz-Vegas
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Kristen C Cooke
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Fiona C Weiss
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Xiaowen Duan
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Sergey Kurdyukov
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Ping-Xin Zhou
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9038; School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan 453003, China
| | - Uttam K Tambar
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9038
| | - Akiyoshi Hirayama
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata 997-0052, Japan; AMED-CREST, Japan Agency for Medical Research and Development (AMED), 1-7-1 Otemachi, Chiyoda-Ku, Tokyo 100-0004, Japan
| | - Satsuki Ikeda
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata 997-0052, Japan
| | - Yushi Kamei
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata 997-0052, Japan
| | - Tomoyoshi Soga
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata 997-0052, Japan; AMED-CREST, Japan Agency for Medical Research and Development (AMED), 1-7-1 Otemachi, Chiyoda-Ku, Tokyo 100-0004, Japan
| | - Gregory J Cooney
- Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia; Sydney Medical School, The University of Sydney, Sydney, New South Wales 2006, Australia.
| | - David E James
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia; Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia; Sydney Medical School, The University of Sydney, Sydney, New South Wales 2006, Australia.
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