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Liu CC, Khan A, Seban N, Littlejohn N, Shah A, Srinivasan S. A homeostatic gut-to-brain insulin antagonist restrains neuronally stimulated fat loss. Nat Commun 2024; 15:6869. [PMID: 39127676 PMCID: PMC11316803 DOI: 10.1038/s41467-024-51077-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 07/29/2024] [Indexed: 08/12/2024] Open
Abstract
In C. elegans mechanisms by which peripheral organs relay internal state information to the nervous system remain unknown, although strong evidence suggests that such signals do exist. Here we report the discovery of a peptide of the ancestral insulin superfamily called INS-7 that functions as an enteroendocrine peptide and is secreted from specialized cells of the intestine. INS-7 secretion is stimulated by food withdrawal, increases during fasting and acts as a bona fide gut-to-brain peptide that attenuates the release of a neuropeptide that drives fat loss in the periphery. Thus, INS-7 functions as a homeostatic signal from the intestine that gates the neuronal drive to stimulate fat loss during food shortage. Mechanistically, INS-7 functions as an antagonist at the canonical DAF-2 receptor and functions via FOXO and AMPK signaling in ASI neurons. Phylogenetic analysis suggests that INS-7 bears greater resemblance to members of the broad insulin/relaxin superfamily than to conventional mammalian insulin and IGF peptides. The discovery of an endogenous insulin antagonist secreted by specialized intestinal cells with enteroendocrine functions suggests unexpected and important properties of the intestine and its role in directing neuronal functions.
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Affiliation(s)
- Chung-Chih Liu
- Department of Neuroscience and Dorris Neuroscience Center, The Scripps Research Institute, San Diego, CA, USA
- The Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, San Diego, CA, USA
| | - Ayub Khan
- Department of Neuroscience and Dorris Neuroscience Center, The Scripps Research Institute, San Diego, CA, USA
| | - Nicolas Seban
- Department of Neuroscience and Dorris Neuroscience Center, The Scripps Research Institute, San Diego, CA, USA
| | - Nicole Littlejohn
- Department of Neuroscience and Dorris Neuroscience Center, The Scripps Research Institute, San Diego, CA, USA
| | - Aayushi Shah
- Department of Neuroscience and Dorris Neuroscience Center, The Scripps Research Institute, San Diego, CA, USA
| | - Supriya Srinivasan
- Department of Neuroscience and Dorris Neuroscience Center, The Scripps Research Institute, San Diego, CA, USA.
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Liu CC, Khan A, Seban N, Littlejohn N, Srinivasan S. A homeostatic gut-to-brain insulin antagonist restrains neuronally stimulated fat loss. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.20.563330. [PMID: 37961386 PMCID: PMC10634694 DOI: 10.1101/2023.10.20.563330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
In C. elegans mechanisms by which peripheral organs relay internal state information to the nervous system remain unknown, although strong evidence suggests that such signals do exist. Here we report the discovery of a peptide of the ancestral insulin superfamily called INS-7 that functions as an enteroendocrine peptide and is secreted from specialized cells of the intestine. INS-7 secretion increases during fasting, and acts as a bona fide gut-to-brain homeostatic signal that attenuates neuronally induced fat loss during food shortage. INS-7 functions as an antagonist at the canonical DAF-2 receptor in the nervous system, and phylogenetic analysis suggests that INS-7 bears greater resemblance to members of the broad insulin/relaxin superfamily than to conventional mammalian insulin and IGF peptides. The discovery of an endogenous insulin antagonist secreted by specialized intestinal cell with enteroendocrine functions suggests that much remains to be learned about the intestine and its role in directing neuronal functions.
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Ma T, Pan X, Wang T, Li X, Luo Y. Toxicity of Per- and Polyfluoroalkyl Substances to Nematodes. TOXICS 2023; 11:593. [PMID: 37505559 PMCID: PMC10385831 DOI: 10.3390/toxics11070593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 06/27/2023] [Accepted: 07/06/2023] [Indexed: 07/29/2023]
Abstract
Per- and polyfluoroalkyl substances (PFASs) are a class of compounds that persist in the environment globally. Besides being transported to the soil and sediments, which act as their sinks, PFASs can be transferred to several species of higher organisms directly or via bacteria, eliciting a wide range of adverse effects. Caenorhabditis elegans has been widely used in toxicological studies and life science research owing to its numerous advantages over traditional vertebrate models; notably, C. elegans has 65% conserved human-disease-associated genes and does not require ethical approvals for experimental use. This review covers a range of topics, from reported accumulation characteristics and lethal concentrations of PFAS in C. elegans to the mechanisms underlying the toxicity of PFAS at different levels, including reproductive, developmental, cellular, neurologic, oxidative, metabolic, immune, and endocrine toxicities. Additionally, the toxicity levels of some PFAS substitutes are summarized. Lastly, we discuss the toxicological mechanisms of these PFAS substitutes and the importance and promising potential of nematodes as in vivo models for life science research, epidemiological studies (obesity, aging, and Alzheimer's disease research), and toxicological investigations of PFASs and other emerging pollutants compared with other soil animals or model organisms.
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Affiliation(s)
- Tingting Ma
- Wenzhou Key Laboratory of Soil Pollution Prevention and Control, Zhejiang Industry and Trade Vocation College, Wenzhou 325002, China
- College of Resource Environment and Tourism, Hubei University of Arts and Science, Xiangyang 441053, China
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Xia Pan
- Wenzhou Key Laboratory of Soil Pollution Prevention and Control, Zhejiang Industry and Trade Vocation College, Wenzhou 325002, China
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Tiantian Wang
- College of Resource Environment and Tourism, Hubei University of Arts and Science, Xiangyang 441053, China
| | - Xiuhua Li
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Yongming Luo
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
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Application of Caenorhabditis elegans in Lipid Metabolism Research. Int J Mol Sci 2023; 24:ijms24021173. [PMID: 36674689 PMCID: PMC9860639 DOI: 10.3390/ijms24021173] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/01/2023] [Accepted: 01/05/2023] [Indexed: 01/11/2023] Open
Abstract
Over the last decade, the development and prevalence of obesity have posed a serious public health risk, which has prompted studies on the regulation of adiposity. With the ease of genetic manipulation, the diversity of the methods for characterizing body fat levels, and the observability of feeding behavior, Caenorhabditis elegans (C. elegans) is considered an excellent model for exploring energy homeostasis and the regulation of the cellular fat storage. In addition, the homology with mammals in the genes related to the lipid metabolism allows many aspects of lipid modulation by the regulators of the central nervous system to be conserved in this ideal model organism. In recent years, as the complex network of genes that maintain an energy balance has been gradually expanded and refined, the regulatory mechanisms of lipid storage have become clearer. Furthermore, the development of methods and devices to assess the lipid levels has become a powerful tool for studies in lipid droplet biology and the regulation of the nematode lipid metabolism. Herein, based on the rapid progress of C. elegans lipid metabolism-related studies, this review outlined the lipid metabolic processes, the major signaling pathways of fat storage regulation, and the primary experimental methods to assess the lipid content in nematodes. Therefore, this model system holds great promise for facilitating the understanding, management, and therapies of human obesity and other metabolism-related diseases.
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Anh NH, Yoon YC, Min YJ, Long NP, Jung CW, Kim SJ, Kim SW, Lee EG, Wang D, Wang X, Kwon SW. Caenorhabditis elegans deep lipidome profiling by using integrative mass spectrometry acquisitions reveals significantly altered lipid networks. J Pharm Anal 2022; 12:743-754. [PMID: 36320604 PMCID: PMC9615529 DOI: 10.1016/j.jpha.2022.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 06/14/2022] [Accepted: 06/15/2022] [Indexed: 12/02/2022] Open
Abstract
Lipidomics coverage improvement is essential for functional lipid and pathway construction. A powerful approach to discovering organism lipidome is to combine various data acquisitions, such as full scan mass spectrometry (full MS), data-dependent acquisition (DDA), and data-independent acquisition (DIA). Caenorhabditis elegans (C. elegans) is a useful model for discovering toxic-induced metabolism, high-throughput drug screening, and a variety of human disease pathways. To determine the lipidome of C. elegans and investigate lipid disruption from the molecular level to the system biology level, we used integrative data acquisition. The methyl-tert-butyl ether method was used to extract L4 stage C. elegans after exposure to triclosan (TCS), perfluorooctanoic acid, and nanopolystyrene (nPS). Full MS, DDA, and DIA integrations were performed to comprehensively profile the C. elegans lipidome by Q-Exactive Plus MS. All annotated lipids were then analyzed using lipid ontology and pathway analysis. We annotated up to 940 lipids from 20 lipid classes involved in various functions and pathways. The biological investigations revealed that when C. elegans were exposed to nPS, lipid droplets were disrupted, whereas plasma membrane-functionalized lipids were likely to be changed in the TCS treatment group. The nPS treatment caused a significant disruption in lipid storage. Triacylglycerol, glycerophospholipid, and ether class lipids were those primarily hindered by toxicants. Finally, toxicant exposure frequently involved numerous lipid-related pathways, including the phosphoinositide 3-kinase/protein kinase B pathway. In conclusion, an integrative data acquisition strategy was used to characterize the C. elegans lipidome, providing valuable biological insights into hypothesis generation and validation. Multiple data acquisitions were used to profile the lipidome of C. elegans. 940 detected lipids of 20 main classes involved in various pathways. Relevant hypotheses were generated using high-coverable lipidomics and pathways analysis.
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Bhat US, Shahi N, Surendran S, Babu K. Neuropeptides and Behaviors: How Small Peptides Regulate Nervous System Function and Behavioral Outputs. Front Mol Neurosci 2021; 14:786471. [PMID: 34924955 PMCID: PMC8674661 DOI: 10.3389/fnmol.2021.786471] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/11/2021] [Indexed: 11/13/2022] Open
Abstract
One of the reasons that most multicellular animals survive and thrive is because of the adaptable and plastic nature of their nervous systems. For an organism to survive, it is essential for the animal to respond and adapt to environmental changes. This is achieved by sensing external cues and translating them into behaviors through changes in synaptic activity. The nervous system plays a crucial role in constantly evaluating environmental cues and allowing for behavioral plasticity in the organism. Multiple neurotransmitters and neuropeptides have been implicated as key players for integrating sensory information to produce the desired output. Because of its simple nervous system and well-established neuronal connectome, C. elegans acts as an excellent model to understand the mechanisms underlying behavioral plasticity. Here, we critically review how neuropeptides modulate a wide range of behaviors by allowing for changes in neuronal and synaptic signaling. This review will have a specific focus on feeding, mating, sleep, addiction, learning and locomotory behaviors in C. elegans. With a view to understand evolutionary relationships, we explore the functions and associated pathophysiology of C. elegans neuropeptides that are conserved across different phyla. Further, we discuss the mechanisms of neuropeptidergic signaling and how these signals are regulated in different behaviors. Finally, we attempt to provide insight into developing potential therapeutics for neuropeptide-related disorders.
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Affiliation(s)
- Umer Saleem Bhat
- Centre for Neuroscience, Indian Institute of Science, Bengaluru, India
- Department of Biological Sciences, Indian Institute of Science Education and Research, Mohali, India
| | - Navneet Shahi
- Centre for Neuroscience, Indian Institute of Science, Bengaluru, India
| | - Siju Surendran
- Centre for Neuroscience, Indian Institute of Science, Bengaluru, India
| | - Kavita Babu
- Centre for Neuroscience, Indian Institute of Science, Bengaluru, India
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Caenorhabditis elegans as a model for obesity research. Curr Res Food Sci 2021; 4:692-697. [PMID: 34647034 PMCID: PMC8501670 DOI: 10.1016/j.crfs.2021.09.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 09/21/2021] [Accepted: 09/22/2021] [Indexed: 02/07/2023] Open
Abstract
Caenorhabditis elegans, a free-living nematode, is an animal model that has been extensively employed in a variety of research fields, including in the study of obesity. Its favorable features include its compact size, short life cycle, large brood size, easy handling, low cost, availability of complete genetic information, 65% conserved human diseases-associated genes, relatively easy genetic manipulation, and research using Caenorhabditis elegans does not require approvals by the Institutional Animal Care and Use Committee. These advantages make Caenorhabditis elegans a great in vivo model for life science research including obesity research. In this review, we provide graphic overviews of Caenorhabditis elegans' basic anatomy, growth conditions, routes of compound delivery, and fat metabolism, both synthesis and degradation pathways, including major signaling pathways involved. Our aim is to provide an overview for researchers interested in applying C. elegans as an in vivo model for the screening and identification of anti-obesity bioactive compounds prior to testing in vertebrate animal models.
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Aghayeva U, Bhattacharya A, Sural S, Jaeger E, Churgin M, Fang-Yen C, Hobert O. DAF-16/FoxO and DAF-12/VDR control cellular plasticity both cell-autonomously and via interorgan signaling. PLoS Biol 2021; 19:e3001204. [PMID: 33891586 PMCID: PMC8099054 DOI: 10.1371/journal.pbio.3001204] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 05/05/2021] [Accepted: 03/23/2021] [Indexed: 01/08/2023] Open
Abstract
Many cell types display the remarkable ability to alter their cellular phenotype in response to specific external or internal signals. Such phenotypic plasticity is apparent in the nematode Caenorhabditis elegans when adverse environmental conditions trigger entry into the dauer diapause stage. This entry is accompanied by structural, molecular, and functional remodeling of a number of distinct tissue types of the animal, including its nervous system. The transcription factor (TF) effectors of 3 different hormonal signaling systems, the insulin-responsive DAF-16/FoxO TF, the TGFβ-responsive DAF-3/SMAD TF, and the steroid nuclear hormone receptor, DAF-12/VDR, a homolog of the vitamin D receptor (VDR), were previously shown to be required for entering the dauer arrest stage, but their cellular and temporal focus of action for the underlying cellular remodeling processes remained incompletely understood. Through the generation of conditional alleles that allowed us to spatially and temporally control gene activity, we show here that all 3 TFs are not only required to initiate tissue remodeling upon entry into the dauer stage, as shown before, but are also continuously required to maintain the remodeled state. We show that DAF-3/SMAD is required in sensory neurons to promote and then maintain animal-wide tissue remodeling events. In contrast, DAF-16/FoxO or DAF-12/VDR act cell-autonomously to control anatomical, molecular, and behavioral remodeling events in specific cell types. Intriguingly, we also uncover non-cell autonomous function of DAF-16/FoxO and DAF-12/VDR in nervous system remodeling, indicating the presence of several insulin-dependent interorgan signaling axes. Our findings provide novel perspectives into how hormonal systems control tissue remodeling.
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Affiliation(s)
- Ulkar Aghayeva
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York, United States of America
| | - Abhishek Bhattacharya
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York, United States of America
| | - Surojit Sural
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York, United States of America
| | - Eliza Jaeger
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York, United States of America
| | - Matthew Churgin
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Christopher Fang-Yen
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York, United States of America
- * E-mail:
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Alcedo J, Prahlad V. Neuromodulators: an essential part of survival. J Neurogenet 2020; 34:475-481. [PMID: 33170042 PMCID: PMC7811185 DOI: 10.1080/01677063.2020.1839066] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/15/2020] [Indexed: 10/23/2022]
Abstract
The coordination between the animal's external environment and internal state requires constant modulation by chemicals known as neuromodulators. Neuromodulators, such as biogenic amines, neuropeptides and cytokines, promote organismal homeostasis. Over the past several decades, Caenorhabditiselegans has grown into a powerful model organism that allows the elucidation of the mechanisms of action of neuromodulators that are conserved across species. In this perspective, we highlight a collection of articles in this issue that describe how neuromodulators optimize C. elegans survival.
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Affiliation(s)
- Joy Alcedo
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - Veena Prahlad
- Department of Biology, Aging Mind and Brain Initiative, and Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, USA
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