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Rai M, Carter SM, Shefali SA, Chawla G, Tennessen JM. Characterization of genetic and molecular tools for studying the endogenous expression of Lactate dehydrogenase in Drosophila melanogaster. PLoS One 2024; 19:e0287865. [PMID: 38170735 PMCID: PMC10763966 DOI: 10.1371/journal.pone.0287865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 12/18/2023] [Indexed: 01/05/2024] Open
Abstract
Drosophila melanogaster larval development relies on a specialized metabolic state that utilizes carbohydrates and other dietary nutrients to promote rapid growth. One unique feature of the larval metabolic program is that Lactate Dehydrogenase (Ldh) activity is highly elevated during this growth phase when compared to other stages of the fly life cycle, indicating that Ldh serves a key role in promoting juvenile development. Previous studies of larval Ldh activity have largely focused on the function of this enzyme at the whole animal level, however, Ldh expression varies significantly among larval tissues, raising the question of how this enzyme promotes tissue-specific growth programs. Here we characterize two transgene reporters and an antibody that can be used to study Ldh expression in vivo. We find that all three tools produce similar Ldh expression patterns. Moreover, these reagents demonstrate that the larval Ldh expression pattern is complex, suggesting the purpose of this enzyme varies across cell types. Overall, our studies validate a series of genetic and molecular reagents that can be used to study glycolytic metabolism in the fly.
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Affiliation(s)
- Madhulika Rai
- Department of Biology, Indiana University, Bloomington, IN, United States of America
| | - Sarah M. Carter
- Department of Biology, Indiana University, Bloomington, IN, United States of America
| | - Shefali A. Shefali
- Department of Biology, Indiana University, Bloomington, IN, United States of America
| | - Geetanjali Chawla
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar Institute of Eminence (SNIoE), Dadri, Uttar Pradesh, India
| | - Jason M. Tennessen
- Department of Biology, Indiana University, Bloomington, IN, United States of America
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Rai M, Carter SM, Shefali SA, Chawla G, Tennessen JM. Characterization of genetic and molecular tools for studying the endogenous expression of Lactate dehydrogenase in Drosophila melanogaster. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.15.545165. [PMID: 37398276 PMCID: PMC10312709 DOI: 10.1101/2023.06.15.545165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Drosophila melanogaster larval development relies on a specialized metabolic state that utilizes carbohydrates and other dietary nutrients to promote rapid growth. One unique feature of the larval metabolic program is that Lactate Dehydrogenase (Ldh) activity is highly elevated during this growth phase when compared to other stages of the fly life cycle, indicating that Ldh serves a key role in promoting juvenile development. Previous studies of larval Ldh activity have largely focused on the function of this enzyme at the whole animal level, however, Ldh expression varies significantly among larval tissues, raising the question of how this enzyme promotes tissue-specific growth programs. Here we characterize two transgene reporters and an antibody that can be used to study Ldh expression in vivo . We find that all three tools produce similar Ldh expression patterns. Moreover, these reagents demonstrate that the larval Ldh expression pattern is complex, suggesting the purpose of this enzyme varies across cell types. Overall, our studies validate a series of genetic and molecular reagents that can be used to study glycolytic metabolism in the fly.
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Affiliation(s)
- Madhulika Rai
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Sarah M. Carter
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | | | - Geetanjali Chawla
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar Institute of Eminence (SNIoE), Dadri, Uttar Pradesh 201314, India
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Heidarian Y, Tourigny JP, Fasteen TD, Mahmoudzadeh NH, Hurlburt AJ, Nemkov T, Reisz JA, D'Alessandro A, Tennessen JM. Metabolomic analysis of Drosophila melanogaster larvae lacking Pyruvate kinase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.05.543743. [PMID: 37333180 PMCID: PMC10274742 DOI: 10.1101/2023.06.05.543743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Pyruvate kinase (Pyk) is a rate-limiting enzyme that catalyzes the final metabolic reaction in glycolysis. The importance of this enzyme, however, extends far beyond ATP production, as Pyk is also known to regulate tissue growth, cell proliferation, and development. Studies of this enzyme in Drosophila melanogaster , however, are complicated by the fact that the fly genome encodes six Pyk paralogs whose functions remain poorly defined. To address this issue, we used sequence distance and phylogenetic approaches to demonstrate that the gene Pyk encodes the enzyme most similar to the mammalian Pyk orthologs, while the other five Drosophila Pyk paralogs have significantly diverged from the canonical enzyme. Consistent with this observation, metabolomic studies of two different Pyk mutant backgrounds revealed that larvae lacking Pyk exhibit a severe block in glycolysis, with a buildup of glycolytic intermediates upstream of pyruvate. However, our analysis also unexpectedly reveals that steady state pyruvate levels are unchanged in Pyk mutants, indicating that larval metabolism maintains pyruvate pool size despite severe metabolic limitations. Consistent with our metabolomic findings, a complementary RNA-seq analysis revealed that genes involved in lipid metabolism and peptidase activity are elevated in Pyk mutants, again indicating that loss of this glycolytic enzyme induces compensatory changes in other aspects of metabolism. Overall, our study provides both insight into how Drosophila larval metabolism adapts to disruption of glycolytic metabolism as well as immediate clinical relevance, considering that Pyk deficiency is the most common congenital enzymatic defect in humans.
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Affiliation(s)
- Yasaman Heidarian
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Jason P Tourigny
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Tess D Fasteen
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | | | | | - Travis Nemkov
- Department of Biochemistry and Molecular Genetics, Anschutz Medical Campus, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Julie A Reisz
- Department of Biochemistry and Molecular Genetics, Anschutz Medical Campus, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Angelo D'Alessandro
- Department of Biochemistry and Molecular Genetics, Anschutz Medical Campus, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Jason M Tennessen
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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Aging and memory are altered by genetically manipulating lactate dehydrogenase in the neurons or glia of flies. Aging (Albany NY) 2023; 15:947-981. [PMID: 36849157 PMCID: PMC10008500 DOI: 10.18632/aging.204565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 02/20/2023] [Indexed: 03/01/2023]
Abstract
The astrocyte-neuron lactate shuttle hypothesis posits that glial-generated lactate is transported to neurons to fuel metabolic processes required for long-term memory. Although studies in vertebrates have revealed that lactate shuttling is important for cognitive function, it is uncertain if this form of metabolic coupling is conserved in invertebrates or is influenced by age. Lactate dehydrogenase (Ldh) is a rate limiting enzyme that interconverts lactate and pyruvate. Here we genetically manipulated expression of Drosophila melanogaster lactate dehydrogenase (dLdh) in neurons or glia to assess the impact of altered lactate metabolism on invertebrate aging and long-term courtship memory at different ages. We also assessed survival, negative geotaxis, brain neutral lipids (the core component of lipid droplets) and brain metabolites. Both upregulation and downregulation of dLdh in neurons resulted in decreased survival and memory impairment with age. Glial downregulation of dLdh expression caused age-related memory impairment without altering survival, while upregulated glial dLdh expression lowered survival without disrupting memory. Both neuronal and glial dLdh upregulation increased neutral lipid accumulation. We provide evidence that altered lactate metabolism with age affects the tricarboxylic acid (TCA) cycle, 2-hydroxyglutarate (2HG), and neutral lipid accumulation. Collectively, our findings indicate that the direct alteration of lactate metabolism in either glia or neurons affects memory and survival but only in an age-dependent manner.
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Rai M, Carter SM, Shefali SA, Mahmoudzadeh NH, Pepin R, Tennessen JM. The Drosophila melanogaster enzyme glycerol-3-phosphate dehydrogenase 1 is required for oogenesis, embryonic development, and amino acid homeostasis. G3 GENES|GENOMES|GENETICS 2022; 12:6583191. [PMID: 35536221 PMCID: PMC9339270 DOI: 10.1093/g3journal/jkac115] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 05/04/2022] [Indexed: 11/22/2022]
Abstract
As the fruit fly, Drosophila melanogaster, progresses from one life stage to the next, many of the enzymes that compose intermediary metabolism undergo substantial changes in both expression and activity. These predictable shifts in metabolic flux allow the fly meet stage-specific requirements for energy production and biosynthesis. In this regard, the enzyme glycerol-3-phosphate dehydrogenase 1 (GPDH1) has been the focus of biochemical genetics studies for several decades and, as a result, is one of the most well-characterized Drosophila enzymes. Among the findings of these earlier studies is that GPDH1 acts throughout the fly lifecycle to promote mitochondrial energy production and triglyceride accumulation while also serving a key role in maintaining redox balance. Here, we expand upon the known roles of GPDH1 during fly development by examining how depletion of both the maternal and zygotic pools of this enzyme influences development, metabolism, and viability. Our findings not only confirm previous observations that Gpdh1 mutants exhibit defects in larval development, lifespan, and fat storage but also reveal that GPDH1 serves essential roles in oogenesis and embryogenesis. Moreover, metabolomics analysis reveals that a Gpdh1 mutant stock maintained in a homozygous state exhibits larval metabolic defects that significantly differ from those observed in the F1 mutant generation. Overall, our findings highlight unappreciated roles for GPDH1 in early development and uncover previously undescribed metabolic adaptations that could allow flies to survive the loss of this key enzyme.
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Affiliation(s)
- Madhulika Rai
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
| | - Sarah M Carter
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
| | - Shefali A Shefali
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
| | | | - Robert Pepin
- Department of Chemistry, Indiana University , Bloomington, IN 47405, USA
| | - Jason M Tennessen
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
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