1
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Öz-Arslan D, Durer ZA, Kan B. G protein-coupled receptor-mediated autophagy in health and disease. Br J Pharmacol 2024. [PMID: 38501194 DOI: 10.1111/bph.16345] [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: 09/01/2023] [Revised: 01/05/2024] [Accepted: 01/27/2024] [Indexed: 03/20/2024] Open
Abstract
G protein-coupled receptors (GPCRs) constitute the largest and most diverse superfamily of mammalian transmembrane proteins. These receptors are involved in a wide range of physiological functions and are targets for more than a third of available drugs in the market. Autophagy is a cellular process involved in degrading damaged proteins and organelles and in recycling cellular components. Deficiencies in autophagy are involved in a variety of pathological conditions. Both GPCRs and autophagy are essential in preserving homeostasis and cell survival. There is emerging evidence suggesting that GPCRs are direct regulators of autophagy. Additionally, autophagic machinery is involved in the regulation of GPCR signalling. The interplay between GPCR and autophagic signalling mechanisms significantly impacts on health and disease; however, there is still an incomplete understanding of the underlying mechanisms and therapeutic implications in different tissues and disease contexts. This review aims to discuss the interactions between GPCR and autophagy signalling. Studies on muscarinic receptors, beta-adrenoceptors, taste receptors, purinergic receptors and adhesion GPCRs are summarized, in relation to autophagy.
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Affiliation(s)
- Devrim Öz-Arslan
- Department of Biophysics, Acibadem MAA University, School of Medicine, Istanbul, Turkey
| | - Zeynep Aslıhan Durer
- Department of Biophysics, Acibadem MAA University, School of Medicine, Istanbul, Turkey
- Department of Biochemistry, Acibadem MAA University, School of Pharmacy, Istanbul, Turkey
| | - Beki Kan
- Department of Biophysics, Acibadem MAA University, School of Medicine, Istanbul, Turkey
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2
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Petratou D, Gjikolaj M, Kaulich E, Schafer W, Tavernarakis N. A proton-inhibited DEG/ENaC ion channel maintains neuronal ionstasis and promotes neuronal survival under stress. iScience 2023; 26:107117. [PMID: 37416472 PMCID: PMC10320524 DOI: 10.1016/j.isci.2023.107117] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 03/28/2023] [Accepted: 06/09/2023] [Indexed: 07/08/2023] Open
Abstract
The nervous system participates in the initiation and modulation of systemic stress. Ionstasis is of utmost importance for neuronal function. Imbalance in neuronal sodium homeostasis is associated with pathologies of the nervous system. However, the effects of stress on neuronal Na+ homeostasis, excitability, and survival remain unclear. We report that the DEG/ENaC family member DEL-4 assembles into a proton-inactivated sodium channel. DEL-4 operates at the neuronal membrane and synapse to modulate Caenorhabditis elegans locomotion. Heat stress and starvation alter DEL-4 expression, which in turn alters the expression and activity of key stress-response transcription factors and triggers appropriate motor adaptations. Similar to heat stress and starvation, DEL-4 deficiency causes hyperpolarization of dopaminergic neurons and affects neurotransmission. Using humanized models of neurodegenerative diseases in C. elegans, we showed that DEL-4 promotes neuronal survival. Our findings provide insights into the molecular mechanisms by which sodium channels promote neuronal function and adaptation under stress.
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Affiliation(s)
- Dionysia Petratou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, 70013 Crete, Greece
- Department of Basic Sciences, Medical School, University of Crete, Heraklion, 71003 Crete, Greece
| | - Martha Gjikolaj
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, 70013 Crete, Greece
- Department of Basic Sciences, Medical School, University of Crete, Heraklion, 71003 Crete, Greece
| | - Eva Kaulich
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, CB2 0QH Cambridge, UK
| | - William Schafer
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, CB2 0QH Cambridge, UK
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, 70013 Crete, Greece
- Department of Basic Sciences, Medical School, University of Crete, Heraklion, 71003 Crete, Greece
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3
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The unfolded protein response reverses the effects of glucose on lifespan in chemically-sterilized C. elegans. Nat Commun 2022; 13:5889. [PMID: 36261415 PMCID: PMC9582010 DOI: 10.1038/s41467-022-33630-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 09/27/2022] [Indexed: 12/02/2022] Open
Abstract
Metabolic diseases often share common traits, including accumulation of unfolded proteins in the endoplasmic reticulum (ER). Upon ER stress, the unfolded protein response (UPR) is activated to limit cellular damage which weakens with age. Here, we show that Caenorhabditis elegans fed a bacterial diet supplemented high glucose at day 5 of adulthood (HGD-5) extends their lifespan, whereas exposed at day 1 (HGD-1) experience shortened longevity. We observed a metabolic shift only in HGD-1, while glucose and infertility synergistically prolonged the lifespan of HGD-5, independently of DAF-16. Notably, we identified that UPR stress sensors ATF-6 and PEK-1 contributed to the longevity of HGD-5 worms, while ire-1 ablation drastically increased HGD-1 lifespan. Together, we postulate that HGD activates the otherwise quiescent UPR in aged worms to overcome ageing-related stress and restore ER homeostasis. In contrast, young animals subjected to HGD provokes unresolved ER stress, conversely leading to a detrimental stress response. Endoplasmic reticulum stress activates the unfolded protein response (UPR). The authors show that glucose extends the lifespan of aged animals by activating the otherwise quiescent UPR while causing a UPR-dependent reduced longevity in young animals
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4
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Bonnard E, Liu J, Zjacic N, Alvarez L, Scholz M. Automatically tracking feeding behavior in populations of foraging C. elegans. eLife 2022; 11:e77252. [PMID: 36083280 PMCID: PMC9462848 DOI: 10.7554/elife.77252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 08/15/2022] [Indexed: 11/13/2022] Open
Abstract
Caenorhabditis elegans feeds on bacteria and other small microorganisms which it ingests using its pharynx, a neuromuscular pump. Currently, measuring feeding behavior requires tracking a single animal, indirectly estimating food intake from population-level metrics, or using restrained animals. To enable large throughput feeding measurements of unrestrained, crawling worms on agarose plates at a single worm resolution, we developed an imaging protocol and a complementary image analysis tool called PharaGlow. We image up to 50 unrestrained crawling worms simultaneously and extract locomotion and feeding behaviors. We demonstrate the tool's robustness and high-throughput capabilities by measuring feeding in different use-case scenarios, such as through development, with genetic and chemical perturbations that result in faster and slower pumping, and in the presence or absence of food. Finally, we demonstrate that our tool is capable of long-term imaging by showing behavioral dynamics of mating animals and worms with different genetic backgrounds. The low-resolution fluorescence microscopes required are readily available in C. elegans laboratories, and in combination with our python-based analysis workflow makes this methodology easily accessible. PharaGlow therefore enables the observation and analysis of the temporal dynamics of feeding and locomotory behaviors with high-throughput and precision in a user-friendly system.
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Affiliation(s)
- Elsa Bonnard
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
| | - Jun Liu
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
| | - Nicolina Zjacic
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
- Institute of Medical Genetics, University of ZurichZurichSwitzerland
| | - Luis Alvarez
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
| | - Monika Scholz
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
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5
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Hughes K, Shah A, Bai X, Adams J, Bauer R, Jackson J, Harris E, Ficca A, Freebairn P, Mohammed S, Fernández EM, Bainbridge C, Brocco M, Stein W, Vidal-Gadea AG. Distinct mechanoreceptor pezo-1 isoforms modulate food intake in the nematode Caenorhabditis elegans. G3 (BETHESDA, MD.) 2022; 12:jkab429. [PMID: 35100363 PMCID: PMC9210275 DOI: 10.1093/g3journal/jkab429] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 12/08/2021] [Indexed: 11/13/2022]
Abstract
Two PIEZO mechanosensitive cation channels, PIEZO1 and PIEZO2, have been identified in mammals, where they are involved in numerous sensory processes. While structurally similar, PIEZO channels are expressed in distinct tissues and exhibit unique properties. How different PIEZOs transduce force, how their transduction mechanism varies, and how their unique properties match the functional needs of the tissues they are expressed in remain all-important unanswered questions. The nematode Caenorhabditis elegans has a single PIEZO ortholog (pezo-1) predicted to have 12 isoforms. These isoforms share many transmembrane domains but differ in those that distinguish PIEZO1 and PIEZO2 in mammals. We used transcriptional and translational reporters to show that putative promoter sequences immediately upstream of the start codon of long pezo-1 isoforms predominantly drive green fluorescent protein (GFP) expression in mesodermally derived tissues (such as muscle and glands). In contrast, sequences upstream of shorter pezo-1 isoforms resulted in GFP expression primarily in neurons. Putative promoters upstream of different isoforms drove GFP expression in different cells of the same organs of the digestive system. The observed unique pattern of complementary expression suggests that different isoforms could possess distinct functions within these organs. We used mutant analysis to show that pharyngeal muscles and glands require long pezo-1 isoforms to respond appropriately to the presence of food. The number of pezo-1 isoforms in C. elegans, their putative differential pattern of expression, and roles in experimentally tractable processes make this an attractive system to investigate the molecular basis for functional differences between members of the PIEZO family of mechanoreceptors.
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Affiliation(s)
- Kiley Hughes
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Ashka Shah
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Xiaofei Bai
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jessica Adams
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Rosemary Bauer
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Janelle Jackson
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Emily Harris
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Alyson Ficca
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Ploy Freebairn
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Shawn Mohammed
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Eliana M Fernández
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (UNSAM), Buenos Aires 1650, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) San Martín, Buenos Aires 1650, Argentina
| | - Chance Bainbridge
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Marcela Brocco
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (UNSAM), Buenos Aires 1650, Argentina
| | - Wolfgang Stein
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
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6
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Hou W, Hao Y, Sun L, Zhao Y, Zheng X, Song L. The dual roles of autophagy and the GPCRs-mediating autophagy signaling pathway after cerebral ischemic stroke. Mol Brain 2022; 15:14. [PMID: 35109896 PMCID: PMC8812204 DOI: 10.1186/s13041-022-00899-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 01/20/2022] [Indexed: 12/17/2022] Open
Abstract
Ischemic stroke, caused by a lack of blood supply in brain tissues, is the third leading cause of human death and disability worldwide, and usually results in sensory and motor dysfunction, cognitive impairment, and in severe cases, even death. Autophagy is a highly conserved lysosome-dependent process in which eukaryotic cells removal misfolded proteins and damaged organelles in cytoplasm, which is critical for energy metabolism, organelle renewal, and maintenance of intracellular homeostasis. Increasing evidence suggests that autophagy plays important roles in pathophysiological mechanisms under ischemic conditions. However, there are still controversies about whether autophagy plays a neuroprotective or damaging role after ischemia. G-protein-coupled receptors (GPCRs), one of the largest protein receptor superfamilies in mammals, play crucial roles in various physiological and pathological processes. Statistics show that GPCRs are the targets of about one-fifth of drugs known in the world, predicting potential values as targets for drug research. Studies have demonstrated that nutritional deprivation can directly or indirectly activate GPCRs, mediating a series of downstream biological processes, including autophagy. It can be concluded that there are interactions between autophagy and GPCRs signaling pathway, which provides research evidence for regulating GPCRs-mediated autophagy. This review aims to systematically discuss the underlying mechanism and dual roles of autophagy in cerebral ischemia, and describe the GPCRs-mediated autophagy, hoping to probe promising therapeutic targets for ischemic stroke through in-depth exploration of the GPCRs-mediated autophagy signaling pathway.
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Affiliation(s)
- Weichen Hou
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Xinmin Street 71#, Changchun, 130021, China
| | - Yulei Hao
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Xinmin Street 71#, Changchun, 130021, China
| | - Li Sun
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Xinmin Street 71#, Changchun, 130021, China
| | - Yang Zhao
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Xinmin Street 71#, Changchun, 130021, China
| | - Xiangyu Zheng
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Xinmin Street 71#, Changchun, 130021, China.
| | - Lei Song
- Department of Respiratory Medicine, Center for Pathogen Biology and Infectious Diseases, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, The First Hospital of Jilin University, Xinmin Street 71#, Changchun, 130021, China.
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7
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Zjacic N, Scholz M. The role of food odor in invertebrate foraging. GENES, BRAIN, AND BEHAVIOR 2022; 21:e12793. [PMID: 34978135 PMCID: PMC9744530 DOI: 10.1111/gbb.12793] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 12/01/2021] [Accepted: 12/18/2021] [Indexed: 11/30/2022]
Abstract
Foraging for food is an integral part of animal survival. In small insects and invertebrates, multisensory information and optimized locomotion strategies are used to effectively forage in patchy and complex environments. Here, the importance of olfactory cues for effective invertebrate foraging is discussed in detail. We review how odors are used by foragers to move toward a likely food source and the recent models that describe this sensory-driven behavior. We argue that smell serves a second function by priming an organism for the efficient exploitation of food. By appraising food odors, invertebrates can establish preferences and better adapt to their ecological niches, thereby promoting survival. The smell of food pre-prepares the gastrointestinal system and primes feeding motor programs for more effective ingestion as well. Optimizing resource utilization affects longevity and reproduction as a result, leading to drastic changes in survival. We propose that models of foraging behavior should include odor priming, and illustrate this with a simple toy model based on the marginal value theorem. Lastly, we discuss the novel techniques and assays in invertebrate research that could investigate the interactions between odor sensing and food intake. Overall, the sense of smell is indispensable for efficient foraging and influences not only locomotion, but also organismal physiology, which should be reflected in behavioral modeling.
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Affiliation(s)
- Nicolina Zjacic
- Max Planck Research Group Neural Information FlowCenter of Advanced European Studies and Research (Caesar)BonnGermany
| | - Monika Scholz
- Max Planck Research Group Neural Information FlowCenter of Advanced European Studies and Research (Caesar)BonnGermany
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8
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Kang C, Avery L. The FMRFamide Neuropeptide FLP-20 Acts as a Systemic Signal for Starvation Responses in Caenorhabditis elegans. Mol Cells 2021; 44:529-537. [PMID: 34140426 PMCID: PMC8334353 DOI: 10.14348/molcells.2021.0051] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/26/2021] [Accepted: 04/08/2021] [Indexed: 02/07/2023] Open
Abstract
Most animals face frequent periods of starvation throughout their entire life and thus need to appropriately adjust their behavior and metabolism during starvation for their survival. Such adaptive responses are regulated by a complex set of systemic signals, including hormones and neuropeptides. While much progress has been made in identifying pathways that regulate nutrient-excessive states, it is still incompletely understood how animals systemically signal their nutrient-deficient states. Here, we showed that the FMRFamide neuropeptide FLP-20 modulates a systemic starvation response in Caenorhabditis elegans. We found that mutation of flp-20 rescued the starvation hypersensitivity of the G protein β-subunit gpb-2 mutants by suppressing excessive autophagy. FLP-20 acted in AIB neurons, where the metabotropic glutamate receptor MGL-2 also functions to modulate a systemic starvation response. Furthermore, FLP-20 modulated starvation-induced fat degradation in a manner dependent on the receptor-type guanylate cyclase GCY-28. Collectively, our results reveal a circuit that senses and signals nutrient-deficient states to modulate a systemic starvation response in multicellular organisms.
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Affiliation(s)
- Chanhee Kang
- School of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | - Leon Avery
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
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9
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Baugh LR, Hu PJ. Starvation Responses Throughout the Caenorhabditiselegans Life Cycle. Genetics 2020; 216:837-878. [PMID: 33268389 PMCID: PMC7768255 DOI: 10.1534/genetics.120.303565] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/17/2020] [Indexed: 02/07/2023] Open
Abstract
Caenorhabditis elegans survives on ephemeral food sources in the wild, and the species has a variety of adaptive responses to starvation. These features of its life history make the worm a powerful model for studying developmental, behavioral, and metabolic starvation responses. Starvation resistance is fundamental to life in the wild, and it is relevant to aging and common diseases such as cancer and diabetes. Worms respond to acute starvation at different times in the life cycle by arresting development and altering gene expression and metabolism. They also anticipate starvation during early larval development, engaging an alternative developmental program resulting in dauer diapause. By arresting development, these responses postpone growth and reproduction until feeding resumes. A common set of signaling pathways mediates systemic regulation of development in each context but with important distinctions. Several aspects of behavior, including feeding, foraging, taxis, egg laying, sleep, and associative learning, are also affected by starvation. A variety of conserved signaling, gene regulatory, and metabolic mechanisms support adaptation to starvation. Early life starvation can have persistent effects on adults and their descendants. With its short generation time, C. elegans is an ideal model for studying maternal provisioning, transgenerational epigenetic inheritance, and developmental origins of adult health and disease in humans. This review provides a comprehensive overview of starvation responses throughout the C. elegans life cycle.
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Affiliation(s)
- L Ryan Baugh
- Department of Biology, Center for Genomic and Computational Biology, Duke University, Durham, North Carolina 27708 and
| | - Patrick J Hu
- Departments of Medicine and Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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10
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Qu Z, Ji S, Zheng S. Glucose and cholesterol induce abnormal cell divisions via DAF-12 and MPK-1 in C. elegans. Aging (Albany NY) 2020; 12:16255-16269. [PMID: 32857726 PMCID: PMC7485695 DOI: 10.18632/aging.103647] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 06/19/2020] [Indexed: 12/26/2022]
Abstract
People exposed to starvation have a high risk of developing cancer later in life, and prior studies have shown these individuals have high insulin and cholesterol levels and are sensitive to glucose. Using C. elegans as a model, we found that glucose and cholesterol can promote survival and cause starved L1 diapause worms to undergo abnormal neuronal cell divisions. Starvation has also been shown to promote long-term survival; however, we found that the functions of glucose and cholesterol in relation to these cell divisions are distinct from their effects on survival. We demonstrate that glucose functions in a DAF-16/FOXO-independent IIS pathway to activate the MAPK ontogenetic signaling to induce neuronal Q-cell divisions, and cholesterol works through DAF-12/steroidogenic pathways to promote these cell divisions. daf-12 and mpk-1/MAPK mutants suppress the function of glucose and cholesterol in these divisions, and a fully functioning dpMPK-1 requires the steroid hormone receptor DAF-12 for these divisions to occur. These afflictions also can be passed on to the immediate progeny. This work indicates a possible link between glucose and cholesterol in starved animals and an increased risk of cancer.
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Affiliation(s)
- Zhi Qu
- School of Nursing and Health, Henan University, Kaifeng 475004, Henan Province, China.,Medical School, Henan University, Kaifeng 475004, Henan Province, China
| | - Shaoping Ji
- School of Basic Medical Sciences, Henan University, Kaifeng 475004, Henan Province, China.,Medical School, Henan University, Kaifeng 475004, Henan Province, China
| | - Shanqing Zheng
- School of Basic Medical Sciences, Henan University, Kaifeng 475004, Henan Province, China.,Medical School, Henan University, Kaifeng 475004, Henan Province, China
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11
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Rangarajan N, Kapoor I, Li S, Drossopoulos P, White KK, Madden VJ, Dohlman HG. Potassium starvation induces autophagy in yeast. J Biol Chem 2020; 295:14189-14202. [PMID: 32788210 DOI: 10.1074/jbc.ra120.014687] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 08/02/2020] [Indexed: 01/04/2023] Open
Abstract
Autophagy is a conserved process that recycles cellular contents to promote survival. Although nitrogen limitation is the canonical inducer of autophagy, recent studies have revealed several other nutrients important to this process. In this study, we used a quantitative, high-throughput assay to identify potassium starvation as a new and potent inducer of autophagy in the yeast Saccharomyces cerevisiae We found that potassium-dependent autophagy requires the core pathway kinases Atg1, Atg5, and Vps34, and other components of the phosphatidylinositol 3-kinase complex. Transmission EM revealed abundant autophagosome formation in response to both stimuli. RNA-Seq indicated distinct transcriptional responses: nitrogen affects transport of ions such as copper, whereas potassium targets the organization of other cellular components. Thus, nitrogen and potassium share the ability to influence molecular supply and demand but do so in different ways. Both inputs promote catabolism through bulk autophagy, but result in distinct mechanisms of cellular remodeling and synthesis.
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Affiliation(s)
- Nambirajan Rangarajan
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Ishani Kapoor
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Shuang Li
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Peter Drossopoulos
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Kristen K White
- Microscopy Services Laboratory, Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Victoria J Madden
- Microscopy Services Laboratory, Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Henrik G Dohlman
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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12
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Rashid S, Pho KB, Mesbahi H, MacNeil LT. Nutrient Sensing and Response Drive Developmental Progression in Caenorhabditis elegans. Bioessays 2020; 42:e1900194. [PMID: 32003906 DOI: 10.1002/bies.201900194] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/22/2019] [Indexed: 12/18/2022]
Abstract
In response to nutrient limitation, many animals, including Caenorhabditis elegans, slow or arrest their development. This process requires mechanisms that sense essential nutrients and induce appropriate responses. When faced with nutrient limitation, C. elegans can induce both short and long-term survival strategies, including larval arrest, decreased developmental rate, and dauer formation. To select the most advantageous strategy, information from many different sensors must be integrated into signaling pathways, including target of rapamycin (TOR) and insulin, that regulate developmental progression. Here, how nutrient information is sensed and integrated into developmental decisions that determine developmental rate and progression in C. elegans is reviewed.
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Affiliation(s)
- Sabih Rashid
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, L8S 4K1, Ontario, Canada
| | - Kim B Pho
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, L8S 4K1, Ontario, Canada
| | - Hiva Mesbahi
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, L8S 4K1, Ontario, Canada
| | - Lesley T MacNeil
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, L8S 4K1, Ontario, Canada.,Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, L8S 4K1, Ontario, Canada.,Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, L8S 4K1, Ontario, Canada
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13
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Shimizu K, Ashida K, Hotta K, Oka K. Food deprivation changes chemotaxis behavior in Caenorhabditis elegans. Biophys Physicobiol 2020; 16:167-172. [PMID: 31984168 PMCID: PMC6975978 DOI: 10.2142/biophysico.16.0_167] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/19/2019] [Indexed: 12/01/2022] Open
Abstract
Exploring for food is important in food-deprived condition. Chemotaxis is one of the important behaviors to search food. Although chemotactic strategies in C. elegans have been well investigated: the pirouette and the weathervane strategies, the change of the chemotactic strategy by food deprivation is largely unclear. Here, we show the change of chemotactic strategy by food deprivation, especially for isoamyl alcohol. To compare chemotaxis under different food-deprivation period, we showed that worms change their chemotactic behaviors by food deprivation. The worms with 1-h food-deprivation change the weathervane strategy. On the other hand, 6-h food deprived animals change the pirouette strategy. These results demonstrate that worms change chemotactic strategy different way depend on period of food deprivation.
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Affiliation(s)
- Kei Shimizu
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Kanagawa 223-8522, Japan
| | - Keita Ashida
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Kanagawa 223-8522, Japan
| | - Kohji Hotta
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Kanagawa 223-8522, Japan
| | - Kotaro Oka
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Kanagawa 223-8522, Japan.,Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung City 80708, Taiwan.,Waseda Research Institute for Science and Engineering, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan
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14
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Bouagnon AD, Lin L, Srivastava S, Liu CC, Panda O, Schroeder FC, Srinivasan S, Ashrafi K. Intestinal peroxisomal fatty acid β-oxidation regulates neural serotonin signaling through a feedback mechanism. PLoS Biol 2019; 17:e3000242. [PMID: 31805041 PMCID: PMC6917301 DOI: 10.1371/journal.pbio.3000242] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 12/17/2019] [Accepted: 11/15/2019] [Indexed: 02/02/2023] Open
Abstract
The ability to coordinate behavioral responses with metabolic status is fundamental to the maintenance of energy homeostasis. In numerous species including Caenorhabditis elegans and mammals, neural serotonin signaling regulates a range of food-related behaviors. However, the mechanisms that integrate metabolic information with serotonergic circuits are poorly characterized. Here, we identify metabolic, molecular, and cellular components of a circuit that links peripheral metabolic state to serotonin-regulated behaviors in C. elegans. We find that blocking the entry of fatty acyl coenzyme As (CoAs) into peroxisomal β-oxidation in the intestine blunts the effects of neural serotonin signaling on feeding and egg-laying behaviors. Comparative genomics and metabolomics revealed that interfering with intestinal peroxisomal β-oxidation results in a modest global transcriptional change but significant changes to the metabolome, including a large number of changes in ascaroside and phospholipid species, some of which affect feeding behavior. We also identify body cavity neurons and an ether-a-go-go (EAG)-related potassium channel that functions in these neurons as key cellular components of the circuitry linking peripheral metabolic signals to regulation of neural serotonin signaling. These data raise the possibility that the effects of serotonin on satiety may have their origins in feedback, homeostatic metabolic responses from the periphery.
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Affiliation(s)
- Aude D. Bouagnon
- Department of Physiology, University of California San Francisco, San Francisco, California, United States of America
| | - Lin Lin
- Department of Physiology, University of California San Francisco, San Francisco, California, United States of America
| | - Shubhi Srivastava
- Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, California, United States of America
| | - Chung-Chih Liu
- Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, California, United States of America
| | - Oishika Panda
- Boyce Thompson Institute, Cornell University, Ithaca, New York, United States of America
| | - Frank C. Schroeder
- Boyce Thompson Institute, Cornell University, Ithaca, New York, United States of America
| | - Supriya Srinivasan
- Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, California, United States of America
| | - Kaveh Ashrafi
- Department of Physiology, University of California San Francisco, San Francisco, California, United States of America
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15
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Rangarajan N, Gordy CL, Askew L, Bevill SM, Elston TC, Errede B, Hurst JH, Kelley JB, Sheetz JB, Suzuki SK, Valentin NH, Young E, Dohlman HG. Systematic analysis of F-box proteins reveals a new branch of the yeast mating pathway. J Biol Chem 2019; 294:14717-14731. [PMID: 31399514 DOI: 10.1074/jbc.ra119.010063] [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: 07/05/2019] [Revised: 08/06/2019] [Indexed: 11/06/2022] Open
Abstract
The mating pathway in yeast Saccharomyces cerevisiae has long been used to reveal new mechanisms of signal transduction. The pathway comprises a pheromone receptor, a heterotrimeric G protein, and intracellular effectors of morphogenesis and transcription. Polarized cell growth, in the direction of a potential mating partner, is accomplished by the G-protein βγ subunits and the small G-protein Cdc42. Transcription induction, needed for cell-cell fusion, is mediated by Gβγ and the mitogen-activated protein kinase (MAPK) scaffold protein Ste5. A potential third pathway is initiated by the G-protein α subunit Gpa1. Gpa1 signaling was shown previously to involve the F-box adaptor protein Dia2 and an endosomal effector protein, the phosphatidylinositol 3-kinase Vps34. Vps34 is also required for proper vacuolar sorting and autophagy. Here, using a panel of reporter assays, we demonstrate that mating pheromone stimulates vacuolar targeting of a cytoplasmic reporter protein and that this process depends on Vps34. Through a systematic analysis of F-box deletion mutants, we show that Dia2 is required to sustain pheromone-induced vacuolar targeting. We also found that other F-box proteins selectively regulate morphogenesis (Ydr306, renamed Pfu1) and transcription (Ucc1). These findings point to the existence of a new and distinct branch of the pheromone-signaling pathway, one that likely leads to vacuolar engulfment of cytoplasmic proteins and recycling of cellular contents in preparation for mating.
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Affiliation(s)
- Nambirajan Rangarajan
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Claire L Gordy
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Lauren Askew
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Samantha M Bevill
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Timothy C Elston
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Beverly Errede
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Jillian H Hurst
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Joshua B Kelley
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Joshua B Sheetz
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Sara Kimiko Suzuki
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599.,Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Natalie H Valentin
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Everett Young
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Henrik G Dohlman
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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16
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A novel gene-diet pair modulates C. elegans aging. PLoS Genet 2018; 14:e1007608. [PMID: 30125273 PMCID: PMC6117094 DOI: 10.1371/journal.pgen.1007608] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 08/30/2018] [Accepted: 08/02/2018] [Indexed: 12/26/2022] Open
Abstract
Diet profoundly affects metabolism and incidences of age-related diseases. Animals adapt their physiology to different food-types, modulating complex life-history traits like aging. The molecular mechanisms linking adaptive capacity to diet with aging are less known. We identify FLR-4 kinase as a novel modulator of aging in C. elegans, depending on bacterial diet. FLR-4 functions to prevent differential activation of the p38MAPK pathway in response to diverse food-types, thereby maintaining normal life span. In a kinase-dead flr-4 mutant, E. coli HT115 (K12 strain), but not the standard diet OP50 (B strain), is able to activate p38MAPK, elevate expression of cytoprotective genes through the nuclear hormone receptor NHR-8 and enhance life span. Interestingly, flr-4 and dietary restriction utilize similar pathways for longevity assurance, suggesting cross-talks between cellular modules that respond to diet quality and quantity. Together, our study discovers a new C. elegans gene-diet pair that controls the plasticity of aging. For animals living in the wild, being able to utilize a wide range of diet is evolutionarily advantageous as they can survive even when their optimal diet is depleted. Since diet is known to influence the rate of aging, animals seem to have evolved intricate mechanisms to maintain homeostasis and normal life span, but the molecular mechanisms are less understood. Using a small nematode, C. elegans as a model, we show that the adaptive capacity to different diet is maintained by a kinase gene. When this gene is mutated, worms start living longer on one strain of bacterial diet but not on the other. We identify the molecular cascade required for this food-type-dependent longevity. We show that this cascade of events significantly overlaps with the pathway that determine food quantity-dependent life span enhancement. Our study thus elucidates a part of the molecular monitoring system that regulates longevity dependent on the available quality and quantity of diet.
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17
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Coleman B, Topalidou I, Ailion M. Modulation of Gq-Rho Signaling by the ERK MAPK Pathway Controls Locomotion in Caenorhabditis elegans. Genetics 2018; 209:523-535. [PMID: 29615470 PMCID: PMC5972424 DOI: 10.1534/genetics.118.300977] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 03/29/2018] [Indexed: 12/17/2022] Open
Abstract
The heterotrimeric G protein Gq regulates neuronal activity through distinct downstream effector pathways. In addition to the canonical Gq effector phospholipase Cβ, the small GTPase Rho was recently identified as a conserved effector of Gq. To identify additional molecules important for Gq signaling in neurons, we performed a forward genetic screen in the nematode Caenorhabditis elegans for suppressors of the hyperactivity and exaggerated waveform of an activated Gq mutant. We isolated two mutations affecting the MAP kinase scaffold protein KSR-1 and found that KSR-1 modulates locomotion downstream of, or in parallel to, the Gq-Rho pathway. Through epistasis experiments, we found that the core ERK MAPK cascade is required for Gq-Rho regulation of locomotion, but that the canonical ERK activator LET-60/Ras may not be required. Through neuron-specific rescue experiments, we found that the ERK pathway functions in head acetylcholine neurons to control Gq-dependent locomotion. Additionally, expression of activated LIN-45/Raf in head acetylcholine neurons is sufficient to cause an exaggerated waveform phenotype and hypersensitivity to the acetylcholinesterase inhibitor aldicarb, similar to an activated Gq mutant. Taken together, our results suggest that the ERK MAPK pathway modulates the output of Gq-Rho signaling to control locomotion behavior in C. elegans.
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Affiliation(s)
- Brantley Coleman
- Department of Biochemistry, University of Washington, Seattle, Washington 98195
| | - Irini Topalidou
- Department of Biochemistry, University of Washington, Seattle, Washington 98195
| | - Michael Ailion
- Department of Biochemistry, University of Washington, Seattle, Washington 98195
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18
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Multilayered Reprogramming in Response to Persistent DNA Damage in C. elegans. Cell Rep 2018; 20:2026-2043. [PMID: 28854356 PMCID: PMC5583510 DOI: 10.1016/j.celrep.2017.08.028] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 06/30/2017] [Accepted: 08/04/2017] [Indexed: 11/23/2022] Open
Abstract
DNA damage causally contributes to aging and age-related diseases. Mutations in nucleotide excision repair (NER) genes cause highly complex congenital syndromes characterized by growth retardation, cancer susceptibility, and accelerated aging in humans. Orthologous mutations in Caenorhabditis elegans lead to growth delay, genome instability, and accelerated functional decline, thus allowing investigation of the consequences of persistent DNA damage during development and aging in a simple metazoan model. Here, we conducted proteome, lipidome, and phosphoproteome analysis of NER-deficient animals in response to UV treatment to gain comprehensive insights into the full range of physiological adaptations to unrepaired DNA damage. We derive metabolic changes indicative of a tissue maintenance program and implicate an autophagy-mediated proteostatic response. We assign central roles for the insulin-, EGF-, and AMPK-like signaling pathways in orchestrating the adaptive response to DNA damage. Our results provide insights into the DNA damage responses in the organismal context.
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19
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Dagenhardt J, Trinh A, Sumner H, Scott J, Aamodt E, Dwyer DS. Insulin Signaling Deficiency Produces Immobility in Caenorhabditis elegans That Models Diminished Motivation States in Man and Responds to Antidepressants. MOLECULAR NEUROPSYCHIATRY 2017; 3:97-107. [PMID: 29230398 DOI: 10.1159/000478049] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 06/06/2017] [Indexed: 01/05/2023]
Abstract
Defects in insulin signaling have been reported in schizophrenia and major depressive disorder, which also share certain negative symptoms such as avolition, anhedonia, and apathy. These symptoms reflect diminished motivational states, which have been modeled in rodents as increased immobility in the forced swimming test. We have discovered that loss-of-function mutations in the insulin receptor (daf-2) and syntaxin (unc-64) genes in Caenorhabditis elegans, brief food deprivation, and exposure to DMSO produce immobility and avolition in non-dauer adults. The animals remain responsive to external stimuli; however, they fail to forage and will remain in place for >12 days or until they die. Their immobility can be prevented with drugs used to treat depression and schizophrenia and that reduce immobility in the forced swimming test. This includes amitriptyline, amoxapine, clozapine, and olanzapine, but not benzodiazepines and haloperidol. Recovery experiments confirm that immobility is induced and maintained by excessive signaling via serotonergic and muscarinic cholinergic pathways. The immobility response described here represents a potential protophenotype for avolition/anhedonia in man. This work may provide clues about why there is a significant increase in depression in patients with diabetes and suggest new therapeutic pathways for disorders featuring diminished motivation as a prominent symptom.
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Affiliation(s)
- Julie Dagenhardt
- Department of Pharmacology, Toxicology and Neuroscience, Los Angeles, USA
| | - Angeline Trinh
- Department of Psychiatry, LSU Health Sciences Center at Shreveport, Los Angeles, USA
| | - Halen Sumner
- Department of Centenary College, Shreveport, Los Angeles, USA
| | - Jeffrey Scott
- Department of Centenary College, Shreveport, Los Angeles, USA
| | - Eric Aamodt
- Department of Biochemistry and Molecular Biology, LSU Health Sciences Center at Shreveport, Los Angeles, USA
| | - Donard S Dwyer
- Department of Pharmacology, Toxicology and Neuroscience, Los Angeles, USA.,Department of Psychiatry, LSU Health Sciences Center at Shreveport, Los Angeles, USA
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20
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Lucanic M, Garrett T, Yu I, Calahorro F, Asadi Shahmirzadi A, Miller A, Gill MS, Hughes RE, Holden‐Dye L, Lithgow GJ. Chemical activation of a food deprivation signal extends lifespan. Aging Cell 2016; 15:832-41. [PMID: 27220516 PMCID: PMC5013014 DOI: 10.1111/acel.12492] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2016] [Indexed: 12/29/2022] Open
Abstract
Model organisms subject to dietary restriction (DR) generally live longer. Accompanying this lifespan extension are improvements in overall health, based on multiple metrics. This indicates that pharmacological treatments that mimic the effects of DR could improve health in humans. To find new chemical structures that extend lifespan, we screened 30 000 synthetic, diverse drug‐like chemicals in Caenorhabditis elegans and identified several structurally related compounds that acted through DR mechanisms. The most potent of these NP1 impinges upon a food perception pathway by promoting glutamate signaling in the pharynx. This results in the overriding of a GPCR pathway involved in the perception of food and which normally acts to decrease glutamate signals. Our results describe the activation of a dietary restriction response through the pharmacological masking of a novel sensory pathway that signals the presence of food. This suggests that primary sensory pathways may represent novel targets for human pharmacology.
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Affiliation(s)
- Mark Lucanic
- Buck Institute for Research on Aging 8001 Redwood Boulevard Novato CA USA
| | - Theo Garrett
- Buck Institute for Research on Aging 8001 Redwood Boulevard Novato CA USA
| | - Ivan Yu
- Buck Institute for Research on Aging 8001 Redwood Boulevard Novato CA USA
- Dominican University of California 50 Acacia Avenue San Rafael CA USA
| | - Fernando Calahorro
- Center for Biological Sciences Institute for Life Sciences University of Southampton Southampton UK
| | - Azar Asadi Shahmirzadi
- Buck Institute for Research on Aging 8001 Redwood Boulevard Novato CA USA
- Davis School of Gerontology University of Southern California Los Angeles CA USA
| | - Aaron Miller
- Buck Institute for Research on Aging 8001 Redwood Boulevard Novato CA USA
| | - Matthew S. Gill
- Department of Metabolism & Aging The Scripps Research Institute‐Scripps Florida 130 Scripps Way Jupiter FL 33458
| | - Robert E. Hughes
- Buck Institute for Research on Aging 8001 Redwood Boulevard Novato CA USA
| | - Lindy Holden‐Dye
- Center for Biological Sciences Institute for Life Sciences University of Southampton Southampton UK
| | - Gordon J. Lithgow
- Buck Institute for Research on Aging 8001 Redwood Boulevard Novato CA USA
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21
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Gravato-Nobre MJ, Vaz F, Filipe S, Chalmers R, Hodgkin J. The Invertebrate Lysozyme Effector ILYS-3 Is Systemically Activated in Response to Danger Signals and Confers Antimicrobial Protection in C. elegans. PLoS Pathog 2016; 12:e1005826. [PMID: 27525822 PMCID: PMC4985157 DOI: 10.1371/journal.ppat.1005826] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 07/25/2016] [Indexed: 12/17/2022] Open
Abstract
Little is known about the relative contributions and importance of antibacterial effectors in the nematode C. elegans, despite extensive work on the innate immune responses in this organism. We report an investigation of the expression, function and regulation of the six ilys (invertebrate-type lysozyme) genes of C. elegans. These genes exhibited a surprising variety of tissue-specific expression patterns and responses to starvation or bacterial infection. The most strongly expressed, ilys-3, was investigated in detail. ILYS-3 protein was expressed constitutively in the pharynx and coelomocytes, and dynamically in the intestine. Analysis of mutants showed that ILYS-3 was required for pharyngeal grinding (disruption of bacterial cells) during normal growth and consequently it contributes to longevity, as well as being protective against bacterial pathogens. Both starvation and challenge with Gram-positive pathogens resulted in ERK-MAPK-dependent up-regulation of ilys-3 in the intestine. The intestinal induction by pathogens, but not starvation, was found to be dependent on MPK-1 activity in the pharynx rather than in the intestine, demonstrating unexpected communication between these two tissues. The coelomocyte expression appeared to contribute little to normal growth or immunity. Recombinant ILYS-3 protein was found to exhibit appropriate lytic activity against Gram-positive cell wall material. Innate immune defenses against bacterial pathogenesis depend on the activation of antibacterial factors. We examined the expression and relative importance of a gene family encoding six invertebrate-type lysozymes in the much-studied nematode C. elegans. The ilys genes exhibit distinct patterns of tissue-specific expression and response to pathogenic challenge and/or starvation. The most abundantly expressed, ilys-3, exhibits constitutive pharyngeal expression, which we show is essential for efficient disruption of bacteria under non-pathogenic growth conditions, and consequently it contributes to normal longevity. ilys-3 is also strongly up-regulated in intestinal cells after starvation or exposure to Gram-positive pathogens such as Microbacterium nematophilum and acts as a ‘slow-effector’ in limiting pathogenic damage from intestinal infections. We show that this induction by pathogens depends on the action of an ERK-MAPK cascade, which acts in pharyngeal rather than intestinal cells; this implies communication between pharynx and intestine. Tagged ILYS-3 protein was detected mainly in recycling endosomes of intestinal cells and in the intestinal lumen after starvation. ILYS-3 was also expressed in coelomocytes (scavenger cells) but we found that these cells make little or no contribution to defense. We examined the enzymatic properties of recombinant ILYS-3 protein, finding that it has lytic activity against M. nematophilum cell-walls.
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Affiliation(s)
| | - Filipa Vaz
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Sergio Filipe
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Ronald Chalmers
- Laboratory of Bacterial Cell Surfaces and Pathogenesis, Instituto de Tecnologia Química e Biológica and Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Jonathan Hodgkin
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
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22
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Kim J, Lee HY, Ahn J, Hyun M, Lee I, Min KJ, You YJ. NHX-5, an Endosomal Na+/H+ Exchanger, Is Associated with Metformin Action. J Biol Chem 2016; 291:18591-9. [PMID: 27435670 DOI: 10.1074/jbc.c116.744037] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Indexed: 01/18/2023] Open
Abstract
Diabetes is one of the most impactful diseases worldwide. The most commonly prescribed anti-diabetic drug is metformin. In this study, we identified an endosomal Na(+)/H(+) exchanger (NHE) as a new potential target of metformin from an unbiased screen in Caenorhabditis elegans The same NHE homolog also exists in flies, where it too mediates the effects of metformin. Our results suggest that endosomal NHEs could be a metformin target and provide an insight into a novel mechanism of action of metformin on regulating the endocytic cycle.
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Affiliation(s)
- Jeongho Kim
- From the Department of Biological Sciences, Inha University, Incheon 22212, South Korea
| | - Hye-Yeon Lee
- From the Department of Biological Sciences, Inha University, Incheon 22212, South Korea
| | - Jheesoo Ahn
- the Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia 23298, and
| | - Moonjung Hyun
- the Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia 23298, and
| | - Inhwan Lee
- the Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia 23298, and
| | - Kyung-Jin Min
- From the Department of Biological Sciences, Inha University, Incheon 22212, South Korea
| | - Young-Jai You
- the Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia 23298, and the Nagoya Research Center for Brain & Neural Circuits, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
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23
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BLIMP-1/BLMP-1 and Metastasis-Associated Protein Regulate Stress Resistant Development in Caenorhabditis elegans. Genetics 2016; 203:1721-32. [PMID: 27334271 DOI: 10.1534/genetics.116.190793] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 06/14/2016] [Indexed: 01/17/2023] Open
Abstract
Environmental stress triggers multilevel adaptations in animal development that depend in part on epigenetic mechanisms. In response to harsh environmental conditions and pheromone signals, Caenorhabditis elegans larvae become the highly stress-resistant and long-lived dauer. Despite extensive studies of dauer formation pathways that integrate specific environmental cues and appear to depend on transcriptional reprogramming, the role of epigenetic regulation in dauer development has remained unclear. Here we report that BLMP-1, the BLIMP-1 ortholog, regulates dauer formation via epigenetic pathways; in the absence of TGF-β signaling (in daf-7 mutants), lack of blmp-1 caused lethality. Using this phenotype, we screened 283 epigenetic factors, and identified lin-40, a homolog of metastasis-associate protein 1 (MTA1) as an interactor of BLMP-1 The interaction between LIN-40 and BLMP-1 is conserved because mammalian homologs for both MTA1 and BLIMP-1 could also interact. From microarray studies, we identified several downstream target genes of blmp-1: npr-3, nhr-23, ptr-4, and sams-1 Among them S-adenosyl methionine synthase (SAMS-1), is the key enzyme for production of SAM used in histone methylation. Indeed, blmp-1 is necessary for controlling histone methylation level in daf-7 mutants, suggesting BLMP-1 regulates the expression of SAMS-1, which in turn may regulate histone methylation and dauer formation. Our results reveal a new interaction between BLMP-1/BLIMP-1 and LIN-40/MTA1, as well as potential epigenetic downstream pathways, whereby these proteins cooperate to regulate stress-specific developmental adaptations.
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24
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Tao J, Ma YC, Yang ZS, Zou CG, Zhang KQ. Octopamine connects nutrient cues to lipid metabolism upon nutrient deprivation. SCIENCE ADVANCES 2016; 2:e1501372. [PMID: 27386520 PMCID: PMC4928904 DOI: 10.1126/sciadv.1501372] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 04/06/2016] [Indexed: 05/21/2023]
Abstract
Starvation is probably the most common stressful situation in nature. In vertebrates, elevation of the biogenic amine norepinephrine levels is common during starvation. However, the precise role of norepinephrine in nutrient deprivation remains largely unknown. We report that in the free-living nematode Caenorhabditis elegans, up-regulation of the biosynthesis of octopamine, the invertebrate counterpart of norepinephrine, serves as a mechanism to adapt to starvation. During nutrient deprivation, the nuclear receptor DAF-12, known to sense nutritional cues, up-regulates the expression of tbh-1 that encodes tyramine β-hydroxylase, a key enzyme for octopamine biosynthesis, in the RIC neurons. Octopamine induces the expression of the lipase gene lips-6 via its receptor SER-3 in the intestine. LIPS-6, in turn, elicits lipid mobilization. Our findings reveal that octopamine acts as an endocrine regulator linking nutrient cues to lipolysis to maintain energy homeostasis, and suggest that such a mechanism may be evolutionally conserved in diverse organisms.
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Affiliation(s)
- Jun Tao
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, Yunnan 650091, China
| | - Yi-Cheng Ma
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, Yunnan 650091, China
| | - Zhong-Shan Yang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, Yunnan 650091, China
- College of Basic Medicine, Yunnan University of Traditional Chinese Medicine, Kunming, Yunnan 650500, China
| | - Cheng-Gang Zou
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, Yunnan 650091, China
- Corresponding author. (C.-G.Z.); (K.-Q.Z.)
| | - Ke-Qin Zhang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, Yunnan 650091, China
- Corresponding author. (C.-G.Z.); (K.-Q.Z.)
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25
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Fat Metabolism Regulates Satiety Behavior in C. elegans. Sci Rep 2016; 6:24841. [PMID: 27097601 PMCID: PMC4838937 DOI: 10.1038/srep24841] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 04/01/2016] [Indexed: 12/27/2022] Open
Abstract
Animals change feeding behavior depending on their metabolic status; starved animals are eager to eat and satiated animals stop eating. C. elegans exhibits satiety quiescence under certain conditions that mimics many aspects of post-prandial sleep in mammals. Here we show that this feeding behavior depends on fat metabolism mediated by the SREBP-SCD pathway, an acetyl-CoA carboxylase (ACC) and certain nuclear hormone receptors (NRs). Mutations of the genes in the SREBP-SCD pathway reduce satiety quiescence. An RNA interference (RNAi) screen of the genes that regulate glucose and fatty acid metabolism identified an ACC necessary for satiety quiescence in C. elegans. ACC catalyzes the first step in de novo fatty acid biosynthesis known to be downstream of the SREBP pathway in mammals. We identified 28 NRs by microarray whose expression changes during refeeding after being starved. When individually knocked down by RNAi, 11 NRs among 28 affect both fat storage and satiety behavior. Our results show that the major fat metabolism pathway regulates feeding behavior and NRs could be the mediators to link the feeding behavior to the metabolic changes.
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26
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Lightfoot JW, Chauhan VM, Aylott JW, Rödelsperger C. Comparative transcriptomics of the nematode gut identifies global shifts in feeding mode and pathogen susceptibility. BMC Res Notes 2016; 9:142. [PMID: 26944260 PMCID: PMC4779222 DOI: 10.1186/s13104-016-1886-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 01/25/2016] [Indexed: 12/20/2022] Open
Abstract
Background The nematode Pristionchus pacificus has been established as a model for comparative studies using the well known Caenorhabditis elegans as a reference. Despite their relatedness, previous studies have revealed highly divergent development and a number of morphological differences including the lack of a pharyngal structure, the grinder, used to physically lyse the ingested bacteria in C. elegans. Results To complement current knowledge about developmental and ecological differences with a better understanding of their feeding modes, we have sequenced the intestinal transcriptomes of both nematodes. In total, we found 464 intestine-enriched genes in P. pacificus and 724 in C. elegans, of which the majority (66 %) has been identified by previous studies. Interestingly, only 15 genes could be identified with shared intestinal enrichment in both species, of which three genes are Hedgehog signaling molecules supporting a highly conserved role of this pathway for intestinal development across all metazoa. At the level of gene families, we find similar divergent trends with only five families displaying significant intestinal enrichment in both species. We compared our data with transcriptomic responses to various pathogens. Strikingly, C. elegans intestine-enriched genes showed highly significant overlaps with pathogen response genes whereas this was not the case for P. pacificus, indicating shifts in pathogen susceptibility that might be explained by altered feeding modes. Conclusions Our study reveals first insights into the evolution of feeding systems and the associated changes in intestinal gene expression that might have facilitated nematodes of the P. pacificus lineage to colonize new environments. These findings deepen our understanding about how morphological and genomic diversity is created during the course of evolution. Electronic supplementary material The online version of this article (doi:10.1186/s13104-016-1886-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- James W Lightfoot
- Department for Evolutionary Biology, Max-Planck Institute for Developmental Biology, Spemannstr. 35-39, Tübingen, Germany.
| | - Veeren M Chauhan
- Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, Boots Science Building, Nottingham, UK.
| | - Jonathan W Aylott
- Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, Boots Science Building, Nottingham, UK.
| | - Christian Rödelsperger
- Department for Evolutionary Biology, Max-Planck Institute for Developmental Biology, Spemannstr. 35-39, Tübingen, Germany.
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Palmisano NJ, Meléndez A. Detection of Autophagy in Caenorhabditis elegans by Western Blotting Analysis of LGG-1. Cold Spring Harb Protoc 2016; 2016:pdb.prot086512. [PMID: 26832685 DOI: 10.1101/pdb.prot086512] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A common way to measure the induction of autophagy in yeast and mammalian cells is to compare the amount of Atg8/LC3-I with that of Atg8-PE/LC3-II by using western blot analysis. This is because changes in the amount of LC3-II correlate closely with changes in the number of autophagosomes present in cells. Atg8/LC3 is initially synthesized as an unprocessed form, which is proteolytically processed to form Atg8/LC3-I, and then this is modified into the phosphatidylethanolamine (PE)-conjugated Atg8-PE/LC3-II form. Atg8/LC3-II is membrane bound, whereas Atg8-PE/LC3-I is cytosolic. By associating with both the inner and outer membranes of the autophagosome, Atg8-PE/LC3-II is the only autophagy reporter that is reliably associated with completed autophagosomes. In the nematode Caenorhabditis elegans, the ortholog of Atg8/LC3 is LGG-1. Here, we discuss how changes in the levels of LGG-1-II (and the paralog LGG-2) protein can, with appropriate controls, be used to monitor autophagy activity in nematodes and present a protocol for monitoring changes in the protein levels of different forms of LGG-1 by western blotting.
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Affiliation(s)
- Nicholas J Palmisano
- Department of Biology, Queens College-CUNY, Flushing, New York 11367; The Graduate Center, The City University of New York, New York 10016
| | - Alicia Meléndez
- Department of Biology, Queens College-CUNY, Flushing, New York 11367; The Graduate Center, The City University of New York, New York 10016
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28
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Zhang H, Chang JT, Guo B, Hansen M, Jia K, Kovács AL, Kumsta C, Lapierre LR, Legouis R, Lin L, Lu Q, Meléndez A, O'Rourke EJ, Sato K, Sato M, Wang X, Wu F. Guidelines for monitoring autophagy in Caenorhabditis elegans. Autophagy 2015; 11:9-27. [PMID: 25569839 PMCID: PMC4502811 DOI: 10.1080/15548627.2014.1003478] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The cellular recycling process of autophagy has been extensively characterized with standard assays in yeast and mammalian cell lines. In multicellular organisms, numerous external and internal factors differentially affect autophagy activity in specific cell types throughout the stages of organismal ontogeny, adding complexity to the analysis of autophagy in these metazoans. Here we summarize currently available assays for monitoring the autophagic process in the nematode C. elegans. A combination of measuring levels of the lipidated Atg8 ortholog LGG-1, degradation of well-characterized autophagic substrates such as germline P granule components and the SQSTM1/p62 ortholog SQST-1, expression of autophagic genes and electron microscopy analysis of autophagic structures are presently the most informative, yet steady-state, approaches available to assess autophagy levels in C. elegans. We also review how altered autophagy activity affects a variety of biological processes in C. elegans such as L1 survival under starvation conditions, dauer formation, aging, and cell death, as well as neuronal cell specification. Taken together, C. elegans is emerging as a powerful model organism to monitor autophagy while evaluating important physiological roles for autophagy in key developmental events as well as during adulthood.
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Key Words
- ASEL, ASE left
- ASER, ASE right
- ATG, autophagy-related
- C. elegans
- ER, endoplasmic reticulum
- GFP, green fluorescent protein
- LC3
- MO, membranous organelle
- PGL, P-granule abnormality
- RER, rough endoplasmic reticulum
- SQST, SeQueSTosome related protein
- SQSTM1
- TEM, transmission electron microscopy
- autophagy
- development
- epg, ectopic PGL granules
- lgg-1, LC3, GABARAP and GATE-16 family
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Affiliation(s)
- Hong Zhang
- a State Key Laboratory of Biomacromolecules; Institute of Biophysics; Chinese Academy of Sciences ; Beijing , China
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29
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Abstract
The compact nervous system of Caenorhabditis elegans and its genetic tractability are features that make this organism highly suitable for investigating energy balance in an animal system. Here, we focus on molecular components and organizational principles emerging from the investigation of pathways that largely originate in the nervous system and regulate feeding behavior but also peripheral fat regulation through neuroendocrine signaling. We provide an overview of studies aimed at understanding how C. elegans integrate internal and external cues in feeding behavior. We highlight some of the similarities and differences in energy balance between C. elegans and mammals. We also provide our perspective on unresolved issues, both conceptual and technical, that we believe have hampered critical evaluation of findings relevant to fat regulation in C. elegans.
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Affiliation(s)
- George A Lemieux
- Department of Physiology, University of California, San Francisco, California 94158;
| | - Kaveh Ashrafi
- Department of Physiology, University of California, San Francisco, California 94158;
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30
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Larance M, Pourkarimi E, Wang B, Brenes Murillo A, Kent R, Lamond AI, Gartner A. Global Proteomics Analysis of the Response to Starvation in C. elegans. Mol Cell Proteomics 2015; 14:1989-2001. [PMID: 25963834 PMCID: PMC4587315 DOI: 10.1074/mcp.m114.044289] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Indexed: 12/31/2022] Open
Abstract
Periodic starvation of animals induces large shifts in metabolism but may also influence many other cellular systems and can lead to adaption to prolonged starvation conditions. To date, there is limited understanding of how starvation affects gene expression, particularly at the protein level. Here, we have used mass-spectrometry-based quantitative proteomics to identify global changes in the Caenorhabditis elegans proteome due to acute starvation of young adult animals. Measuring changes in the abundance of over 5,000 proteins, we show that acute starvation rapidly alters the levels of hundreds of proteins, many involved in central metabolic pathways, highlighting key regulatory responses. Surprisingly, we also detect changes in the abundance of chromatin-associated proteins, including specific linker histones, histone variants, and histone posttranslational modifications associated with the epigenetic control of gene expression. To maximize community access to these data, they are presented in an online searchable database, the Encyclopedia of Proteome Dynamics (http://www.peptracker.com/epd/).
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Affiliation(s)
- Mark Larance
- From the ‡Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dow St, Dundee, United Kingdom, DD15EH
| | - Ehsan Pourkarimi
- From the ‡Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dow St, Dundee, United Kingdom, DD15EH
| | - Bin Wang
- From the ‡Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dow St, Dundee, United Kingdom, DD15EH
| | - Alejandro Brenes Murillo
- From the ‡Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dow St, Dundee, United Kingdom, DD15EH
| | - Robert Kent
- From the ‡Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dow St, Dundee, United Kingdom, DD15EH
| | - Angus I Lamond
- From the ‡Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dow St, Dundee, United Kingdom, DD15EH
| | - Anton Gartner
- From the ‡Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dow St, Dundee, United Kingdom, DD15EH
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31
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Dillon J, Franks CJ, Murray C, Edwards RJ, Calahorro F, Ishihara T, Katsura I, Holden-Dye L, O'Connor V. Metabotropic Glutamate Receptors: MODULATORS OF CONTEXT-DEPENDENT FEEDING BEHAVIOUR IN C. ELEGANS. J Biol Chem 2015; 290:15052-65. [PMID: 25869139 DOI: 10.1074/jbc.m114.606608] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Indexed: 11/06/2022] Open
Abstract
Glutamatergic neurotransmission is evolutionarily conserved across animal phyla. A major class of glutamate receptors consists of the metabotropic glutamate receptors (mGluRs). In C. elegans, three mGluR genes, mgl-1, mgl-2, and mgl-3, are organized into three subgroups, similar to their mammalian counterparts. Cellular reporters identified expression of the mgls in the nervous system of C. elegans and overlapping expression in the pharyngeal microcircuit that controls pharyngeal muscle activity and feeding behavior. The overlapping expression of mgls within this circuit allowed the investigation of receptor signaling per se and in the context of receptor interactions within a neural network that regulates feeding. We utilized the pharmacological manipulation of neuronally regulated pumping of the pharyngeal muscle in the wild-type and mutants to investigate MGL function. This defined a net mgl-1-dependent inhibition of pharyngeal pumping that is modulated by mgl-3 excitation. Optogenetic activation of the pharyngeal glutamatergic inputs combined with electrophysiological recordings from the isolated pharyngeal preparations provided further evidence for a presynaptic mgl-1-dependent regulation of pharyngeal activity. Analysis of mgl-1, mgl-2, and mgl-3 mutant feeding behavior in the intact organism after acute food removal identified a significant role for mgl-1 in the regulation of an adaptive feeding response. Our data describe the molecular and cellular organization of mgl-1, mgl-2, and mgl-3. Pharmacological analysis identified that, in these paradigms, mgl-1 and mgl-3, but not mgl-2, can modulate the pharyngeal microcircuit. Behavioral analysis identified mgl-1 as a significant determinant of the glutamate-dependent modulation of feeding, further highlighting the significance of mGluRs in complex C. elegans behavior.
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Affiliation(s)
- James Dillon
- From the Centre for Biological Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, United Kingdom,
| | - Christopher J Franks
- From the Centre for Biological Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, United Kingdom
| | | | - Richard J Edwards
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, New South Wales 2052, Australia
| | - Fernando Calahorro
- From the Centre for Biological Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, United Kingdom
| | - Takeshi Ishihara
- the Department of Biology, Graduate School of Science, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan, and
| | - Isao Katsura
- the National Institute of Genetics, Yata 1111, Mishima, Shizuoka-ken, 411-8540, Japan
| | - Lindy Holden-Dye
- From the Centre for Biological Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, United Kingdom
| | - Vincent O'Connor
- From the Centre for Biological Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, United Kingdom,
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32
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Autophagy as a pro-death pathway. Immunol Cell Biol 2014; 93:35-42. [PMID: 25331550 DOI: 10.1038/icb.2014.85] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 09/01/2014] [Accepted: 09/08/2014] [Indexed: 12/12/2022]
Abstract
The evolutionarily conserved catabolic process of autophagy involves the degradation of cytoplasmic components through lysosomal enzymes. Basal levels of autophagy maintain cellular homeostasis and under stress conditions high levels of autophagy are induced. It is often under such stress conditions that high levels of autophagy and cell death have been observed, leading to the idea that autophagy may act as an executioner of cell death. However the notion of autophagy as a cell death mechanism has been controversial and remains mechanistically undefined. There is now growing evidence that in specific contexts autophagy can indeed facilitate cell death. The pro-death role of autophagy is however complicated due to the extensive cross-talk between different signalling pathways. This review summarises the examples of where autophagy acts as a means of cell death and discusses the association of autophagy with the different cell death pathways.
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33
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Chuang M, Chisholm AD. Insights into the functions of the death associated protein kinases from C. elegans and other invertebrates. Apoptosis 2014; 19:392-7. [PMID: 24242918 DOI: 10.1007/s10495-013-0943-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The death associated protein kinases (DAPK) are a phylogenetically widespread family of calcium-regulated serine/threonine kinases, initially identified from their roles in apoptosis. Subsequent studies, principally in vertebrate cells or models, have elucidated the functions of the DAPK family in autophagy and tumor suppression. Invertebrate genetic model organisms such as Drosophila and C. elegans have revealed additional functions for DAPK and related kinases. In the nematode C. elegans, the sole DAPK family member DAPK-1 positively regulates starvation-induced autophagy. Genetic analysis in C. elegans has revealed that DAPK-1 also acts as a negative regulator of epithelial innate immune responses in the epidermis. This negative regulatory role for DAPK in innate immunity may be analogous to the roles of mammalian DAPK in inflammatory responses.
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Affiliation(s)
- Marian Chuang
- Cell and Developmental Biology Section, Division of Biological Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
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34
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Lemieux GA, Ashrafi K. Insights and challenges in using C. elegans for investigation of fat metabolism. Crit Rev Biochem Mol Biol 2014; 50:69-84. [PMID: 25228063 DOI: 10.3109/10409238.2014.959890] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
C. elegans provides a genetically tractable system for deciphering the homeostatic mechanisms that underlie fat regulation in intact organisms. Here, we provide an overview of the recent advances in the C. elegans fat field with particular attention to studies of C. elegans lipid droplets, the complex links between lipases, autophagy, and lifespan, and analyses of key transcriptional regulatory mechanisms that coordinate lipid homeostasis. These studies demonstrate the ancient origins of mammalian and C. elegans fat regulatory pathways and highlight how C. elegans is being used to identify and analyze novel lipid pathways that are then shown to function similarly in mammals. Despite its many advantages, study of fat regulation in C. elegans is currently faced with a number of conceptual and methodological challenges. We critically evaluate some of the assumptions in the field and highlight issues that we believe should be taken into consideration when interpreting lipid content data in C. elegans.
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Affiliation(s)
- George A Lemieux
- Department of Physiology, University of California , San Francisco, CA , USA
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35
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Bio-orthogonal labeling as a tool to visualize and identify newly synthesized proteins in Caenorhabditis elegans. Nat Protoc 2014; 9:2237-55. [DOI: 10.1038/nprot.2014.150] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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36
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Autophagy protects C. elegans against necrosis during Pseudomonas aeruginosa infection. Proc Natl Acad Sci U S A 2014; 111:12480-5. [PMID: 25114220 DOI: 10.1073/pnas.1405032111] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Autophagy, a conserved pathway that delivers intracellular materials into lysosomes for degradation, is involved in development, aging, and a variety of diseases. Accumulating evidence demonstrates that autophagy plays a protective role against infectious diseases by diminishing intracellular pathogens, including bacteria, viruses, and parasites. However, the mechanism by which autophagy regulates innate immunity remains largely unknown. Here, we show that autophagy is involved in host defense against a pathogenic bacterium Pseudomonas aeruginosa in the metazoan Caenorhabditis elegans. P. aeruginosa infection induces autophagy via a conserved extracellular signal-regulated kinase (ERK). Intriguingly, impairment of autophagy does not influence the intestinal accumulation of P. aeruginosa, but instead induces intestinal necrosis. Inhibition of necrosis results in the survival of autophagy-deficient worms after P. aeruginosa infection. These findings reveal a previously unidentified role for autophagy in protection against necrosis triggered by pathogenic bacteria in C. elegans and implicate that such a function of autophagy may be conserved through the inflammatory response in diverse organisms.
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37
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Walker AJ, Ressurreição M, Rothermel R. Exploring the function of protein kinases in schistosomes: perspectives from the laboratory and from comparative genomics. Front Genet 2014; 5:229. [PMID: 25132840 PMCID: PMC4117187 DOI: 10.3389/fgene.2014.00229] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 06/30/2014] [Indexed: 01/09/2023] Open
Abstract
Eukaryotic protein kinases are well conserved through evolution. The genome of Schistosoma mansoni, which causes intestinal schistosomiasis, encodes over 250 putative protein kinases with all of the main eukaryotic groups represented. However, unraveling functional roles for these kinases is a considerable endeavor, particularly as protein kinases regulate multiple and sometimes overlapping cell and tissue functions in organisms. In this article, elucidating protein kinase signal transduction and function in schistosomes is considered from the perspective of the state-of-the-art methodologies used and comparative organismal biology, with a focus on current advances and future directions. Using the free-living nematode Caenorhabditis elegans as a comparator we predict roles for various schistosome protein kinases in processes vital for host invasion and successful parasitism such as sensory behavior, growth and development. It is anticipated that the characterization of schistosome protein kinases in the context of parasite function will catalyze cutting edge research into host-parasite interactions and will reveal new targets for developing drug interventions against human schistosomiasis.
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Affiliation(s)
- Anthony J Walker
- Laboratory of Molecular Parasitology, School of Life Sciences, Kingston University Kingston upon Thames, UK
| | - Margarida Ressurreição
- Laboratory of Molecular Parasitology, School of Life Sciences, Kingston University Kingston upon Thames, UK
| | - Rolf Rothermel
- Laboratory of Molecular Parasitology, School of Life Sciences, Kingston University Kingston upon Thames, UK
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38
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Cunningham KA, Bouagnon AD, Barros AG, Lin L, Malard L, Romano-Silva MA, Ashrafi K. Loss of a neural AMP-activated kinase mimics the effects of elevated serotonin on fat, movement, and hormonal secretions. PLoS Genet 2014; 10:e1004394. [PMID: 24921650 PMCID: PMC4055570 DOI: 10.1371/journal.pgen.1004394] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 04/07/2014] [Indexed: 12/30/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is an evolutionarily conserved master regulator of metabolism and a therapeutic target in type 2 diabetes. As an energy sensor, AMPK activity is responsive to both metabolic inputs, for instance the ratio of AMP to ATP, and numerous hormonal cues. As in mammals, each of two genes, aak-1 and aak-2, encode for the catalytic subunit of AMPK in C. elegans. Here we show that in C. elegans loss of aak-2 mimics the effects of elevated serotonin signaling on fat reduction, slowed movement, and promoting exit from dauer arrest. Reconstitution of aak-2 in only the nervous system restored wild type fat levels and movement rate to aak-2 mutants and reconstitution in only the ASI neurons was sufficient to significantly restore dauer maintenance to the mutant animals. As in elevated serotonin signaling, inactivation of AAK-2 in the ASI neurons caused enhanced secretion of dense core vesicles from these neurons. The ASI neurons are the site of production of the DAF-7 TGF-β ligand and the DAF-28 insulin, both of which are secreted by dense core vesicles and play critical roles in whether animals stay in dauer or undergo reproductive development. These findings show that elevated levels of serotonin promote enhanced secretions of systemic regulators of pro-growth and differentiation pathways through inactivation of AAK-2. As such, AMPK is not only a recipient of hormonal signals but can also be an upstream regulator. Our data suggest that some of the physiological phenotypes previously attributed to peripheral AAK-2 activity on metabolic targets may instead be due to the role of this kinase in neural serotonin signaling.
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Affiliation(s)
- Katherine A. Cunningham
- Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - Aude D. Bouagnon
- Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - Alexandre G. Barros
- Instituto Nacional de Ciência e Tecnologia de Medicina Molecular, Faculdade de Medicina da Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Lin Lin
- Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - Leandro Malard
- Departamento de Física, Instituto de Ciências Exatas da Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Marco Aurélio Romano-Silva
- Instituto Nacional de Ciência e Tecnologia de Medicina Molecular, Faculdade de Medicina da Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Kaveh Ashrafi
- Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
- * E-mail:
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39
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Ressurreição M, De Saram P, Kirk RS, Rollinson D, Emery AM, Page NM, Davies AJ, Walker AJ. Protein kinase C and extracellular signal-regulated kinase regulate movement, attachment, pairing and egg release in Schistosoma mansoni. PLoS Negl Trop Dis 2014; 8:e2924. [PMID: 24921927 PMCID: PMC4055629 DOI: 10.1371/journal.pntd.0002924] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 04/19/2014] [Indexed: 01/22/2023] Open
Abstract
Protein kinases C (PKCs) and extracellular signal-regulated kinases (ERKs) are evolutionary conserved cell signalling enzymes that coordinate cell function. Here we have employed biochemical approaches using ‘smart’ antibodies and functional screening to unravel the importance of these enzymes to Schistosoma mansoni physiology. Various PKC and ERK isotypes were detected, and were differentially phosphorylated (activated) throughout the various S. mansoni life stages, suggesting isotype-specific roles and differences in signalling complexity during parasite development. Functional kinase mapping in adult worms revealed that activated PKC and ERK were particularly associated with the adult male tegument, musculature and oesophagus and occasionally with the oesophageal gland; other structures possessing detectable activated PKC and/or ERK included the Mehlis' gland, ootype, lumen of the vitellaria, seminal receptacle and excretory ducts. Pharmacological modulation of PKC and ERK activity in adult worms using GF109203X, U0126, or PMA, resulted in significant physiological disturbance commensurate with these proteins occupying a central position in signalling pathways associated with schistosome muscular activity, neuromuscular coordination, reproductive function, attachment and pairing. Increased activation of ERK and PKC was also detected in worms following praziquantel treatment, with increased signalling associated with the tegument and excretory system and activated ERK localizing to previously unseen structures, including the cephalic ganglia. These findings support roles for PKC and ERK in S. mansoni homeostasis, and identify these kinase groups as potential targets for chemotherapeutic treatments against human schistosomiasis, a neglected tropical disease of enormous public health significance. Parasitic blood flukes, also called schistosomes, cause human schistosomiasis, a neglected tropical disease and major public health problem in developing countries, especially sub-Saharan Africa. Sustainable control of schistosomiasis is difficult, mainly because the complex life cycle of the parasite involves a freshwater snail host, and the ability of the parasite to evade the immune response of the human host and to survive for many years. Little is yet known about the cellular mechanisms in schistosomes and how they regulate parasite homeostasis, development and behaviour. In this paper, the nature of intracellular signalling by protein kinases C (PKCs) and extracellular signal-regulated kinases (ERKs) in schistosomes is studied and these proteins are found to be vital for the coordination of processes fundamental to parasite survival, such as muscular activity and reproductive function. Our results contribute to an understanding of molecular events regulating schistosome function and identify PKCs and ERKs as possible targets for the development of new chemotherapeutic treatments against schistosomiasis.
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Affiliation(s)
- Margarida Ressurreição
- Molecular Parasitology Laboratory, School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, United Kingdom
- Wolfson Wellcome Biomedical Laboratories, Life Sciences Department, Natural History Museum, London, United Kingdom
| | - Paulu De Saram
- Molecular Parasitology Laboratory, School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, United Kingdom
- Wolfson Wellcome Biomedical Laboratories, Life Sciences Department, Natural History Museum, London, United Kingdom
| | - Ruth S. Kirk
- Molecular Parasitology Laboratory, School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, United Kingdom
| | - David Rollinson
- Wolfson Wellcome Biomedical Laboratories, Life Sciences Department, Natural History Museum, London, United Kingdom
| | - Aidan M. Emery
- Wolfson Wellcome Biomedical Laboratories, Life Sciences Department, Natural History Museum, London, United Kingdom
| | - Nigel M. Page
- Molecular Parasitology Laboratory, School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, United Kingdom
| | - Angela J. Davies
- Molecular Parasitology Laboratory, School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, United Kingdom
| | - Anthony J. Walker
- Molecular Parasitology Laboratory, School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, United Kingdom
- * E-mail:
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40
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Trojanowski NF, Padovan-Merhar O, Raizen DM, Fang-Yen C. Neural and genetic degeneracy underlies Caenorhabditis elegans feeding behavior. J Neurophysiol 2014; 112:951-61. [PMID: 24872529 DOI: 10.1152/jn.00150.2014] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Degenerate networks, in which structurally distinct elements can perform the same function or yield the same output, are ubiquitous in biology. Degeneracy contributes to the robustness and adaptability of networks in varied environmental and evolutionary contexts. However, how degenerate neural networks regulate behavior in vivo is poorly understood, especially at the genetic level. Here, we identify degenerate neural and genetic mechanisms that underlie excitation of the pharynx (feeding organ) in the nematode Caenorhabditis elegans using cell-specific optogenetic excitation and inhibition. We show that the pharyngeal neurons MC, M2, M4, and I1 form multiple direct and indirect excitatory pathways in a robust network for control of pharyngeal pumping. I1 excites pumping via MC and M2 in a state-dependent manner. We identify nicotinic and muscarinic receptors through which the pharyngeal network regulates feeding rate. These results identify two different mechanisms by which degeneracy is manifest in a neural circuit in vivo.
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Affiliation(s)
- Nicholas F Trojanowski
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Olivia Padovan-Merhar
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - David M Raizen
- Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania;
| | - Christopher Fang-Yen
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania; and Department of Physics, Korea University, Anam-dong, Seongbuk-gu, Seoul, South Korea
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Wauson EM, Dbouk HA, Ghosh AB, Cobb MH. G protein-coupled receptors and the regulation of autophagy. Trends Endocrinol Metab 2014; 25:274-82. [PMID: 24751357 PMCID: PMC4082244 DOI: 10.1016/j.tem.2014.03.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 03/14/2014] [Accepted: 03/17/2014] [Indexed: 01/06/2023]
Abstract
Autophagy is an important catabolic cellular process that eliminates damaged and unnecessary cytoplasmic proteins and organelles. Basal autophagy occurs during normal physiological conditions, but the activity of this process can be significantly altered in human diseases. Thus, defining the regulatory inputs and signals that control autophagy is essential. Nutrients are key modulators of autophagy. Although autophagy is generally accepted to be regulated in a cell-autonomous fashion, recent studies suggest that nutrients can modulate autophagy in a systemic manner by inducing the secretion of hormones and neurotransmitters that regulate G protein-coupled receptors (GPCRs). Emerging studies show that GPCRs also regulate autophagy by directly detecting extracellular nutrients. We review the role of GPCRs in autophagy regulation, highlighting their potential as therapeutic drug targets.
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Affiliation(s)
- Eric M Wauson
- Department of Physiology and Pharmacology, Des Moines University, Des Moines, IA 50312, USA.
| | - Hashem A Dbouk
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9041, USA
| | - Anwesha B Ghosh
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9041, USA
| | - Melanie H Cobb
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9041, USA.
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The C. elegans VIG-1 and FRM-1 modulate carbachol-stimulated ERK1/2 activation in chinese hamster ovary cells expressing the muscarinic acetylcholine receptor GAR-3. Neurochem Res 2014; 39:777-84. [PMID: 24604007 DOI: 10.1007/s11064-014-1268-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 02/19/2014] [Accepted: 02/25/2014] [Indexed: 01/22/2023]
Abstract
Many neurotransmitter receptors are known to interact with a variety of intracellular proteins that modulate signaling processes. In an effort to understand the molecular mechanism by which acetylcholine (ACh) signaling is modulated, we searched for proteins that interact with GAR-3, the Caenorhabditis elegans homolog of muscarinic ACh receptors. We isolated two proteins, VIG-1 and FRM-1, in a yeast two-hybrid screen of a C. elegans cDNA library using the third intracellular (i3) loop of GAR-3 as bait. To test whether these proteins regulate ACh signaling, we utilized Chinese hamster ovary (CHO) cells stably expressing GAR-3 (GAR-3/CHO cells). Previously we have shown that the cholinergic agonist carbachol stimulates extracellular signal-regulated kinases 1 and 2 (ERK1/2) activation in an atropine-sensitive manner in this cell line. When VIG-1 was transiently expressed in GAR-3/CHO cells, carbachol-stimulated ERK1/2 activation was substantially reduced. In contrast, transient expression of FRM-1 significantly enhanced carbachol-stimulated ERK1/2 activation. Neither VIG-1 nor FRM-1 expression appeared to alter the affinity between GAR-3 and carbachol. In support of this notion, expression of these proteins did not affect GAR-3-mediated phospholipase C activation. To verify the modulation of ERK1/2 activity by VIG-1 and FRM-1, we used an i3 loop deletion mutant of GAR-3 (termed GAR-3Δi3). Carbachol treatment evoked robust ERK1/2 activation in CHO cells stably expressing the deletion mutant (GAR-3Δi3/CHO cells). However, transient expression of either VIG-1 or FRM-1 had little effect on carbachol-stimulated ERK1/2 activation in GAR-3Δi3/CHO cells. Taken together, these results indicate that VIG-1 and FRM-1 regulate GAR-3-mediated ERK1/2 activation by interacting with the i3 loop of GAR-3.
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43
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Gallagher T, You YJ. Falling asleep after a big meal: Neuronal regulation of satiety. WORM 2014; 3:e27938. [PMID: 25057453 PMCID: PMC4091210 DOI: 10.4161/worm.27938] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 01/06/2014] [Accepted: 01/21/2014] [Indexed: 11/19/2022]
Abstract
C. elegans has become an ideal model to study genetics of appetite control and energy metabolism because of its robust conservation in molecular mechanisms underlying appetite control and in regulation of the relevant feeding behavior. Satiety behavior in worms in particular shows striking similarities to that in mammals, as a worm becomes quiescent after a big meal, mimicking post-prandial sleep in mammals. Here we review our recent finding regarding the neuronal regulation of the behavior and the implication of the finding such as cyclicity of behavioral states. Based on the finding, we propose a rather speculative but intriguing view of how metabolism could link to post-prandial sleep.
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Affiliation(s)
- Thomas Gallagher
- Department of Biochemistry and Molecular Biology; Virginia Commonwealth University; Richmond, VA USA
| | - Young-Jai You
- Department of Biochemistry and Molecular Biology; Virginia Commonwealth University; Richmond, VA USA
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Lemieux GA, Keiser MJ, Sassano MF, Laggner C, Mayer F, Bainton RJ, Werb Z, Roth BL, Shoichet BK, Ashrafi K. In silico molecular comparisons of C. elegans and mammalian pharmacology identify distinct targets that regulate feeding. PLoS Biol 2013; 11:e1001712. [PMID: 24260022 PMCID: PMC3833878 DOI: 10.1371/journal.pbio.1001712] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 10/04/2013] [Indexed: 11/18/2022] Open
Abstract
This paper takes advantage of similarities between the C. elegans and human pharmacopeia to identify and validate pharmacological targets that regulate C. elegans feeding rates. Phenotypic screens can identify molecules that are at once penetrant and active on the integrated circuitry of a whole cell or organism. These advantages are offset by the need to identify the targets underlying the phenotypes. Additionally, logistical considerations limit screening for certain physiological and behavioral phenotypes to organisms such as zebrafish and C. elegans. This further raises the challenge of elucidating whether compound-target relationships found in model organisms are preserved in humans. To address these challenges we searched for compounds that affect feeding behavior in C. elegans and sought to identify their molecular mechanisms of action. Here, we applied predictive chemoinformatics to small molecules previously identified in a C. elegans phenotypic screen likely to be enriched for feeding regulatory compounds. Based on the predictions, 16 of these compounds were tested in vitro against 20 mammalian targets. Of these, nine were active, with affinities ranging from 9 nM to 10 µM. Four of these nine compounds were found to alter feeding. We then verified the in vitro findings in vivo through genetic knockdowns, the use of previously characterized compounds with high affinity for the four targets, and chemical genetic epistasis, which is the effect of combined chemical and genetic perturbations on a phenotype relative to that of each perturbation in isolation. Our findings reveal four previously unrecognized pathways that regulate feeding in C. elegans with strong parallels in mammals. Together, our study addresses three inherent challenges in phenotypic screening: the identification of the molecular targets from a phenotypic screen, the confirmation of the in vivo relevance of these targets, and the evolutionary conservation and relevance of these targets to their human orthologs. Many beneficial pharmacological interventions were first discovered by observing the effects of perturbation of intact biological systems by small organic molecules without a priori knowledge of their targets. This forward pharmacological approach has the advantage of directly identifying new pharmacological agents that are active on complex biological processes. However, because of experimental feasibility, systematic application of this approach is generally limited to small animals such as the roundworm C. elegans and zebrafish, raising the question of whether use of these animals could identify compounds that act on ortholgous mammalian targets. A significant challenge in addressing this question is the determination of the molecular identities of the compounds' targets responsible for the desired phenotypic outcomes. Here we describe a computational approach for target identification based on structural similarities of newly identified compounds to known ligand interactions with mostly mammalian targets. For several of the compounds emerging from a C. elegans phenotypic screen, we predict and confirm mammalian targets using in vitro binding assays. Using genetic and pharmacological assays, we then demonstrate that a subset of these compounds alter C. elegans feeding rates through the C. elegans counterparts of the predicted mammalian targets.
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Affiliation(s)
- George A. Lemieux
- Department of Anatomy, University of California, San Francisco, California, United States of America
| | - Michael J. Keiser
- SeaChange Pharmaceuticals Inc., San Francisco, California, United States of America
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California, United States of America
| | - Maria F. Sassano
- Department of Pharmacology, University of North Carolina Medical School, Chapel Hill, North Carolina, United States of America
| | - Christian Laggner
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California, United States of America
| | - Fahima Mayer
- Department of Physiology, University of California, San Francisco, California, United States of America
| | - Roland J. Bainton
- Department of Anesthesiology, University of California, San Francisco, California, United States of America
| | - Zena Werb
- Department of Anatomy, University of California, San Francisco, California, United States of America
| | - Bryan L. Roth
- Department of Pharmacology, University of North Carolina Medical School, Chapel Hill, North Carolina, United States of America
- * E-mail: (BLR); (BKS); (KA)
| | - Brian K. Shoichet
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California, United States of America
- * E-mail: (BLR); (BKS); (KA)
| | - Kaveh Ashrafi
- Department of Physiology, University of California, San Francisco, California, United States of America
- * E-mail: (BLR); (BKS); (KA)
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Baugh LR. To grow or not to grow: nutritional control of development during Caenorhabditis elegans L1 arrest. Genetics 2013; 194:539-55. [PMID: 23824969 PMCID: PMC3697962 DOI: 10.1534/genetics.113.150847] [Citation(s) in RCA: 176] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 05/09/2013] [Indexed: 12/30/2022] Open
Abstract
It is widely appreciated that larvae of the nematode Caenorhabditis elegans arrest development by forming dauer larvae in response to multiple unfavorable environmental conditions. C. elegans larvae can also reversibly arrest development earlier, during the first larval stage (L1), in response to starvation. "L1 arrest" (also known as "L1 diapause") occurs without morphological modification but is accompanied by increased stress resistance. Caloric restriction and periodic fasting can extend adult lifespan, and developmental models are critical to understanding how the animal is buffered from fluctuations in nutrient availability, impacting lifespan. L1 arrest provides an opportunity to study nutritional control of development. Given its relevance to aging, diabetes, obesity and cancer, interest in L1 arrest is increasing, and signaling pathways and gene regulatory mechanisms controlling arrest and recovery have been characterized. Insulin-like signaling is a critical regulator, and it is modified by and acts through microRNAs. DAF-18/PTEN, AMP-activated kinase and fatty acid biosynthesis are also involved. The nervous system, epidermis, and intestine contribute systemically to regulation of arrest, but cell-autonomous signaling likely contributes to regulation in the germline. A relatively small number of genes affecting starvation survival during L1 arrest are known, and many of them also affect adult lifespan, reflecting a common genetic basis ripe for exploration. mRNA expression is well characterized during arrest, recovery, and normal L1 development, providing a metazoan model for nutritional control of gene expression. In particular, post-recruitment regulation of RNA polymerase II is under nutritional control, potentially contributing to a rapid and coordinated response to feeding. The phenomenology of L1 arrest will be reviewed, as well as regulation of developmental arrest and starvation survival by various signaling pathways and gene regulatory mechanisms.
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Affiliation(s)
- L Ryan Baugh
- Department of Biology, Duke Center for Systems Biology, Duke University, Durham, North Carolina 27708-0338, USA.
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Alterations in gene expression in Caenorhabditis elegans associated with organophosphate pesticide intoxication and recovery. BMC Genomics 2013; 14:291. [PMID: 23631360 PMCID: PMC3760450 DOI: 10.1186/1471-2164-14-291] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 04/20/2013] [Indexed: 01/13/2023] Open
Abstract
Background The principal toxicity of acute organophosphate (OP) pesticide poisoning is the disruption of neurotransmission through inhibition of acetylcholinesterase (AChE). However, other mechanisms leading to persistent effects and neurodegeneration remain controversial and difficult to detect. Because Caenorhabditis elegans is relatively resistant to OP lethality—particularly through the inhibition of AChE—studies in this nematode provide an opportunity to observe alterations in global gene expression following OP exposure that cannot be readily observed in less resistant organisms. Results We exposed cultures of worms in axenic, defined medium to dichlorvos under three exposure protocols. In the first, worms were exposed continuously throughout the experiment. In the second and third, the worms were exposed for either 2 or 8 h, the dichlorvos was washed out of the culture, and the worms were allowed to recover. We then analyzed gene expression using whole genome microarrays from RNA obtained from worms sampled at multiple time points throughout the exposure. The worms showed a time-dependent increase in the expression of genes involved in stress responses. Early in the exposure, the predominant effect was on metabolic processes, while at later times, an immune-like response and cellular repair mechanisms dominated the expression pattern. Following removal of dichlorvos, the gene expression in the worms appeared to relatively rapidly return to steady-state levels. Conclusion The changes in gene expression observed in the worms following exposure to dichlorvos point towards two potential mechanisms of toxicity: inhibition of AChE and mitochondrial disruption.
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dnc-1/dynactin 1 knockdown disrupts transport of autophagosomes and induces motor neuron degeneration. PLoS One 2013; 8:e54511. [PMID: 23408943 PMCID: PMC3567092 DOI: 10.1371/journal.pone.0054511] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 12/12/2012] [Indexed: 11/25/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive loss of motor neurons. We previously showed that the expression of dynactin 1, an axon motor protein regulating retrograde transport, is markedly reduced in spinal motor neurons of sporadic ALS patients, although the mechanisms by which decreased dynactin 1 levels cause neurodegeneration have yet to be elucidated. The accumulation of autophagosomes in degenerated motor neurons is another key pathological feature of sporadic ALS. Since autophagosomes are cargo of dynein/dynactin complexes and play a crucial role in the turnover of several organelles and proteins, we hypothesized that the quantitative loss of dynactin 1 disrupts the transport of autophagosomes and induces the degeneration of motor neuron. In the present study, we generated a Caenorhabditis elegans model in which the expression of DNC-1, the homolog of dynactin 1, is specifically knocked down in motor neurons. This model exhibited severe motor defects together with axonal and neuronal degeneration. We also observed impaired movement and increased number of autophagosomes in the degenerated neurons. Furthermore, the combination of rapamycin, an activator of autophagy, and trichostatin which facilitates axonal transport dramatically ameliorated the motor phenotype and axonal degeneration of this model. Thus, our results suggest that decreased expression of dynactin 1 induces motor neuron degeneration and that the transport of autophagosomes is a novel and substantial therapeutic target for motor neuron degeneration.
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Physiological control of germline development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 757:101-31. [PMID: 22872476 DOI: 10.1007/978-1-4614-4015-4_5] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The intersection between developmental programs and environmental conditions that alter physiology is a growing area of research interest. The C. elegans germ line is emerging as a particularly sensitive and powerful model for these studies. The germ line is subject to environmentally regulated diapause points that allow worms to withstand harsh conditions both prior to and after reproduction commences. It also responds to more subtle changes in physiological conditions. Recent studies demonstrate that different aspects of germ line development are sensitive to environmental and physiological changes and that conserved signaling pathways such as the AMPK, Insulin/IGF, TGFβ, and TOR-S6K, and nuclear hormone receptor pathways mediate this sensitivity. Some of these pathways genetically interact with but appear distinct from previously characterized mechanisms of germline cell fate control such as Notch signaling. Here, we review several aspects of hermaphrodite germline development in the context of "feasting," "food-limited," and "fasting" conditions. We also consider connections between lifespan, metabolism and the germ line, and we comment on special considerations for examining germline development under altered environmental and physiological conditions. Finally, we summarize the major outstanding questions in the field.
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Lee I, Hendrix A, Kim J, Yoshimoto J, You YJ. Metabolic rate regulates L1 longevity in C. elegans. PLoS One 2012; 7:e44720. [PMID: 22970296 PMCID: PMC3435313 DOI: 10.1371/journal.pone.0044720] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 08/09/2012] [Indexed: 12/23/2022] Open
Abstract
Animals have to cope with starvation. The molecular mechanisms by which animals survive long-term starvation, however, are not clearly understood. When they hatch without food, C. elegans arrests development at the first larval stage (L1) and survives more than two weeks. Here we show that the survival span of arrested L1s, which we call L1 longevity, is a starvation response regulated by metabolic rate during starvation. A high rate of metabolism shortens the L1 survival span, whereas a low rate of metabolism lengthens it. The longer worms are starved, the slower they grow once they are fed, suggesting that L1 arrest has metabolic costs. Furthermore, mutants of genes that regulate metabolism show altered L1 longevity. Among them, we found that AMP-dependent protein kinase (AMPK), as a key energy sensor, regulates L1 longevity by regulating this metabolic arrest. Our results suggest that L1 longevity is determined by metabolic rate and that AMPK as a master regulator of metabolism controls this arrest so that the animals survive long-term starvation.
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Affiliation(s)
- Inhwan Lee
- Departments of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Amber Hendrix
- Departments of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Jeongho Kim
- Department of Biological Science, Inha University, Incheon, Korea
| | - Jennifer Yoshimoto
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Young-Jai You
- Departments of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America
- * E-mail:
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Abstract
Food is important to any animal, and a large part of the behavioral repertoire is concerned with ensuring adequate nutrition. Two main nutritional sensations, hunger and satiety, produce opposite behaviors. Hungry animals seek food, increase exploratory behavior and continue feeding once they encounter food. Satiated animals decrease exploratory behavior, take rest, and stop feeding. The signals of hunger or satiety and their effects on physiology and behavior will depend not only on the animal's current nutritional status but also on its experience and the environment in which the animal evolved. In our novel, nutritionally rich environment, improper control of appetite contributes to diseases from anorexia to the current epidemic of obesity. Despite extraordinary recent advances, genetic contribution to appetite control is still poorly understood partly due to lack of simple genetic model systems. In this review, we will discuss current understanding of molecular and cellular mechanisms by which animals regulate food intake depending on their nutritional status. Then, focusing on relatively less known muscarinic and cGMP signals, we will discuss how the molecular and behavioral aspects of hunger and satiety are conserved in a simple invertebrate model system, C. elegans so as for us to use it to understand the genetics of appetite control.
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Affiliation(s)
- Young-Jai You
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia
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