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Ma G, Gasser RB, Wang T, Korhonen PK, Young ND. Toward integrative 'omics of the barber's pole worm and related parasitic nematodes. INFECTION GENETICS AND EVOLUTION 2020; 85:104500. [PMID: 32795511 DOI: 10.1016/j.meegid.2020.104500] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 08/05/2020] [Accepted: 08/07/2020] [Indexed: 12/15/2022]
Abstract
Advances in nucleic acid sequencing, mass spectrometry and computational biology have facilitated the identification, annotation and analysis of genes, transcripts, proteins and metabolites in model nematodes (Caenorhabditis elegans and Pristionchus pacificus) and socioeconomically important parasitic nematodes (Clades I, III, IV and V). Significant progress has been made in genomics and transcriptomics as well as in the proteomics and lipidomics of Haemonchus contortus (the barber's pole worm) - one of the most pathogenic representatives of the order Strongylida. Here, we review salient aspects of genomics, transcriptomics, proteomics, lipidomics, glycomics and functional genomics, and discuss the rise of integrative 'omics of this economically important parasite. Although our knowledge of the molecular biology, genetics and biochemistry of H. contortus and related species has progressed significantly, much remains to be explored, particularly in areas such as drug resistance, unique/unknown genes, host-parasite interactions, parasitism and the pathogenesis of disease, by integrating the use of multiple 'omics methods. This approach should lead to a better understanding of H. contortus and its relatives at a 'systems biology' level, and should assist in developing new interventions against these parasites.
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Affiliation(s)
- Guangxu Ma
- College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, China; Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia.
| | - Robin B Gasser
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia.
| | - Tao Wang
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia.
| | - Pasi K Korhonen
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia.
| | - Neil D Young
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia.
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Otarigho B, Aballay A. Cholesterol Regulates Innate Immunity via Nuclear Hormone Receptor NHR-8. iScience 2020; 23:101068. [PMID: 32361270 PMCID: PMC7195545 DOI: 10.1016/j.isci.2020.101068] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 03/09/2020] [Accepted: 04/13/2020] [Indexed: 02/06/2023] Open
Abstract
Cholesterol is an essential nutrient for the function of diverse biological processes and for steroid biosynthesis across metazoans. However, the role of cholesterol in immune function remains understudied. Using the nematode Caenorhabditis elegans, which depends on the external environment for cholesterol, we studied the relationship between cholesterol and innate immunity. We found that the transporter CHUP-1 is required for the effect of cholesterol in the development of innate immunity and that the cholesterol-mediated immune response requires the nuclear hormone receptor NHR-8. Cholesterol acts through NHR-8 to transcriptionally regulate immune genes that are controlled by conserved immune pathways, including a p38/PMK-1 MAPK pathway, a DAF-2/DAF-16 insulin pathway, and an Nrf/SKN-1 pathway. Our results indicate that cholesterol plays a key role in the activation of conserved microbicidal pathways that are essential for survival against bacterial infections.
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Affiliation(s)
- Benson Otarigho
- Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, OR 97239, USA
| | - Alejandro Aballay
- Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, OR 97239, USA.
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Park S, Park JY, Paik YK. A Molecular Basis for Reciprocal Regulation between Pheromones and Hormones in Response to Dietary Cues in C. elegans. Int J Mol Sci 2020; 21:ijms21072366. [PMID: 32235409 PMCID: PMC7177881 DOI: 10.3390/ijms21072366] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 03/27/2020] [Accepted: 03/27/2020] [Indexed: 01/31/2023] Open
Abstract
Under stressful conditions, the early larvae of C. elegans enter dauer diapause, a non-aging period, driven by the seemingly opposite influence of ascaroside pheromones (ASCRs) and steroid hormone dafachronic acids (DAs). However, the molecular basis of how these small molecules engage in competitive crosstalk in coordination with insulin/IGF-1 signaling (IIS) remains elusive. Here we report a novel transcriptional regulatory pathway that seems to operate between the ASCR and DA biosynthesis under ad libitum (AL) feeding conditions or bacterial deprivation (BD). Although expression of the ASCR and DA biosynthetic genes reciprocally inhibit each other, ironically and interestingly, such dietary cue-mediated modulation requires the presence of the competitors. Under BD, induction of ASCR biosynthetic gene expression required DA, while ASCR suppresses the expression of the DA biosynthetic gene daf-36. The negative regulation of DA by ASCR was IIS-dependent, whereas daf-36 regulation appeared to be independent of IIS. These observations suggest that the presence of ASCR determines the IIS-dependency of DA gene expression regardless of dietary conditions. Thus, our work defines a molecular basis for a novel reciprocal gene regulation of pheromones and hormones to cope with stressful conditions during development and aging.
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Elucidating the molecular and developmental biology of parasitic nematodes: Moving to a multiomics paradigm. ADVANCES IN PARASITOLOGY 2020; 108:175-229. [PMID: 32291085 DOI: 10.1016/bs.apar.2019.12.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In the past two decades, significant progress has been made in the sequencing, assembly, annotation and analyses of genomes and transcriptomes of parasitic worms of socioeconomic importance. This progress has somewhat improved our knowledge and understanding of these pathogens at the molecular level. However, compared with the free-living nematode Caenorhabditis elegans, the areas of functional genomics, transcriptomics, proteomics and metabolomics of parasitic nematodes are still in their infancy, and there are major gaps in our knowledge and understanding of the molecular biology of parasitic nematodes. The information on signalling molecules, molecular pathways and microRNAs (miRNAs) that are known to be involved in developmental processes in C. elegans and the availability of some molecular resources (draft genomes, transcriptomes and some proteomes) for selected parasitic nematodes provide a basis to start exploring the developmental biology of parasitic nematodes. Indeed, some studies have identified molecules and pathways that might associate with developmental processes in related, parasitic nematodes, such as Haemonchus contortus (barber's pole worm). However, detailed information is often scant and 'omics resources are limited, preventing a proper integration of 'omic data sets and comprehensive analyses. Moreover, little is known about the functional roles of pheromones, hormones, signalling pathways and post-transcriptional/post-translational regulations in the development of key parasitic nematodes throughout their entire life cycles. Although C. elegans is an excellent model to assist molecular studies of parasitic nematodes, its use is limited when it comes to explorations of processes that are specific to parasitism within host animals. A deep understanding of parasitic nematodes, such as H. contortus, requires substantially enhanced resources and the use of integrative 'omics approaches for analyses. The improved genome and well-established in vitro larval culture system for H. contortus provide unprecedented opportunities for comprehensive studies of the transcriptomes (mRNA and miRNA), proteomes (somatic, excretory/secretory and phosphorylated proteins) and lipidomes (e.g., polar and neutral lipids) of this nematode. Such resources should enable in-depth explorations of its developmental biology at a level, not previously possible. The main aims of this review are (i) to provide a background on the development of nematodes, with a particular emphasis on the molecular aspects involved in the dauer formation and exit in C. elegans; (ii) to critically appraise the current state of knowledge of the developmental biology of parasitic nematodes and identify key knowledge gaps; (iii) to cover salient aspects of H. contortus, with a focus on the recent advances in genomics, transcriptomics, proteomics and lipidomics as well as in vitro culturing systems; (iv) to review recent advances in our knowledge and understanding of the molecular and developmental biology of H. contortus using an integrative multiomics approach, and discuss the implications of this approach for detailed explorations of signalling molecules, molecular processes and pathways likely associated with nematode development, adaptation and parasitism, and for the identification of novel intervention targets against these pathogens. Clearly, the multiomics approach established recently is readily applicable to exploring a wide range of interesting and socioeconomically significant parasitic worms (including also trematodes and cestodes) at the molecular level, and to elucidate host-parasite interactions and disease processes.
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Selection and gene flow shape niche-associated variation in pheromone response. Nat Ecol Evol 2019; 3:1455-1463. [PMID: 31548647 PMCID: PMC6764921 DOI: 10.1038/s41559-019-0982-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 08/14/2019] [Indexed: 11/18/2022]
Abstract
From quorum sensing in bacteria to pheromone signaling in social insects, chemical communication mediates interactions among individuals in a local population. In Caenorhabditis elegans, ascaroside pheromones can dictate local population density, in which high levels of pheromones inhibit the reproductive maturation of individuals. Little is known about how natural genetic diversity affects the pheromone responses of individuals from diverse habitats. Here, we show that a niche-associated variation in pheromone receptor genes contributes to natural differences in pheromone responses. We identified putative loss-of-function deletions that impair duplicated pheromone receptor genes (srg-36 and srg-37), which were shown previously to be lost in population-dense laboratory cultures. A common natural deletion in srg-37 arose recently from a single ancestral population that spread throughout the world and underlies reduced pheromone sensitivity across the global C. elegans population. We found that many local populations harbor individuals with wild-type or a deletion allele of srg-37, suggesting that balancing selection has maintained the recent variation in this pheromone receptor gene. The two srg-37 genotypes are associated with niche diversity underlying boom-and-bust population dynamics. We hypothesize that human activities likely contributed to the gene flow and balancing selection of srg-37 variation through facilitating migration of species and providing favorable niche for recently arose srg-37 deletion.
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Ma G, Wang T, Korhonen PK, Young ND, Nie S, Ang CS, Williamson NA, Reid GE, Gasser RB. Dafachronic acid promotes larval development in Haemonchus contortus by modulating dauer signalling and lipid metabolism. PLoS Pathog 2019; 15:e1007960. [PMID: 31335899 PMCID: PMC6677322 DOI: 10.1371/journal.ppat.1007960] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 08/02/2019] [Accepted: 07/04/2019] [Indexed: 02/07/2023] Open
Abstract
Here, we discovered an endogenous dafachronic acid (DA) in the socioeconomically important parasitic nematode Haemonchus contortus. We demonstrate that DA promotes larval exsheathment and development in this nematode via a relatively conserved nuclear hormone receptor (DAF-12). This stimulatory effect is dose- and time-dependent, and relates to a modulation of dauer-like signalling, and glycerolipid and glycerophospholipid metabolism, likely via a negative feedback loop. Specific chemical inhibition of DAF-9 (cytochrome P450) was shown to significantly reduce the amount of endogenous DA in H. contortus; compromise both larval exsheathment and development in vitro; and modulate lipid metabolism. Taken together, this evidence shows that DA plays a key functional role in the developmental transition from the free-living to the parasitic stage of H. contortus by modulating the dauer-like signalling pathway and lipid metabolism. Understanding the intricacies of the DA-DAF-12 system and associated networks in H. contortus and related parasitic nematodes could pave the way to new, nematode-specific treatments. In the present study, using an integrative multi-omics approach, we show that dafachronic acid (DA) plays a critical functional role in the developmental transition in larvae of the parasitic nematode Haemonchus contortus (barber’s pole worm) by modulating the dauer-like signalling pathway and lipid metabolism. The DA-DAF-12 signalling module in H. contortus provides a paradigm to explore its developmental and reproductive biology at the molecular level, to study physiochemical cross-talk between the parasite and its hosts, and to discover novel anthelmintic targets.
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Affiliation(s)
- Guangxu Ma
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia
| | - Tao Wang
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia
| | - Pasi K. Korhonen
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia
| | - Neil D. Young
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia
| | - Shuai Nie
- Bio21 Mass Spectrometry and Proteomics Facility, The University of Melbourne, Parkville, Victoria, Australia
| | - Ching-Seng Ang
- Bio21 Mass Spectrometry and Proteomics Facility, The University of Melbourne, Parkville, Victoria, Australia
| | - Nicholas A. Williamson
- Bio21 Mass Spectrometry and Proteomics Facility, The University of Melbourne, Parkville, Victoria, Australia
| | - Gavin E. Reid
- School of Chemistry, The University of Melbourne, Parkville, Victoria, Australia
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Robin B. Gasser
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia
- * E-mail:
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Ma G, Wang T, Korhonen PK, Stroehlein AJ, Young ND, Gasser RB. Dauer signalling pathway model for Haemonchus contortus. Parasit Vectors 2019; 12:187. [PMID: 31036054 PMCID: PMC6489264 DOI: 10.1186/s13071-019-3419-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 03/28/2019] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Signalling pathways have been extensively investigated in the free-living nematode Caenorhabditis elegans, but very little is known about these pathways in parasitic nematodes. Here, we constructed a model for the dauer-associated signalling pathways in an economically highly significant parasitic worm, Haemonchus contortus. METHODS Guided by data and information available for C. elegans, we used extensive genomic and transcriptomic datasets to infer gene homologues in the dauer-associated pathways, explore developmental transcriptomic, proteomic and phosphoproteomic profiles in H. contortus and study selected molecular structures. RESULTS The canonical cyclic guanosine monophosphate (cGMP), transforming growth factor-β (TGF-β), insulin-like growth factor 1 (IGF-1) and steroid hormone signalling pathways of H. contortus were inferred to represent a total of 61 gene homologues. Compared with C. elegans, H. contortus has a reduced set of genes encoding insulin-like peptides, implying evolutionary and biological divergences between the parasitic and free-living nematodes. Similar transcription profiles were found for all gene homologues between the infective stage of H. contortus and dauer stage of C. elegans. High transcriptional levels for genes encoding G protein-coupled receptors (GPCRs), TGF-β, insulin-like ligands (e.g. ins-1, ins-17 and ins-18) and transcriptional factors (e.g. daf-16) in the infective L3 stage of H. contortus were suggestive of critical functional roles in this stage. Conspicuous protein expression patterns and extensive phosphorylation of some components of these pathways suggested marked post-translational modifications also in the L3 stage. The high structural similarity in the DAF-12 ligand binding domain among nematodes indicated functional conservation in steroid (i.e. dafachronic acid) signalling linked to worm development. CONCLUSIONS Taken together, this pathway model provides a basis to explore hypotheses regarding biological processes and regulatory mechanisms (via particular microRNAs, phosphorylation events and/or lipids) associated with the development of H. contortus and related nematodes as well as parasite-host cross talk, which could aid the discovery of new therapeutic targets.
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Affiliation(s)
- Guangxu Ma
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, VIC 3010 Australia
| | - Tao Wang
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, VIC 3010 Australia
| | - Pasi K. Korhonen
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, VIC 3010 Australia
| | - Andreas J. Stroehlein
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, VIC 3010 Australia
| | - Neil D. Young
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, VIC 3010 Australia
| | - Robin B. Gasser
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, VIC 3010 Australia
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Ma G, Wang T, Korhonen PK, Nie S, Reid GE, Stroehlein AJ, Koehler AV, Chang BCH, Hofmann A, Young ND, Gasser RB. Comparative bioinformatic analysis suggests that specific dauer-like signalling pathway components regulate Toxocara canis development and migration in the mammalian host. Parasit Vectors 2019; 12:32. [PMID: 30642380 PMCID: PMC6332619 DOI: 10.1186/s13071-018-3265-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 12/12/2018] [Indexed: 01/28/2023] Open
Abstract
Background Toxocara canis is quite closely related to Ascaris suum but its biology is more complex, involving a phase of arrested development (diapause or hypobiosis) in tissues as well as transplacental and transmammary transmission routes. In the present study, we explored and compared dauer-like signalling pathways of T. canis and A. suum to infer which components in these pathways might associate with, or regulate, this added complexity in T. canis. Methods Guided by information for Caenorhabditis elegans, we bioinformatically inferred and compared components of dauer-like signalling pathways in T. canis and A. suum using genomic and transcriptomic data sets. In these two ascaridoids, we also explored endogenous dafachronic acids (DAs), which are known to be critical in regulating larval developmental processes in C. elegans and other nematodes, by liquid chromatography-mass spectrometry (LC-MS). Results Orthologues of C. elegans dauer signalling genes were identified in T. canis (n = 55) and A. suum (n = 51), inferring the presence of a dauer-like signalling pathway in both species. Comparisons showed clear differences between C. elegans and these ascaridoids as well as between T. canis and A. suum, particularly in the transforming growth factor-β (TGF-β) and insulin-like signalling pathways. Specifically, in both A. suum and T. canis, there was a paucity of genes encoding SMAD transcription factor-related protein (daf-3, daf-5, daf-8 and daf-14) and insulin/insulin-like peptide (daf-28, ins-4, ins-6 and ins-7) homologues, suggesting an evolution and adaptation of the signalling pathway in these parasites. In T. canis, there were more orthologues coding for homologues of antagonist insulin-like peptides (Tc-ins-1 and Tc-ins-18), an insulin receptor substrate (Tc-ist-1) and a serine/threonine kinase (Tc-akt-1) than in A. suum, suggesting potentiated functional roles for these molecules in regulating larval diapause and reactivation. A relatively conserved machinery was proposed for DA synthesis in the two ascaridoids, and endogenous Δ4- and Δ7-DAs were detected in them by LC-MS analysis. Differential transcription analysis between T. canis and A. suum suggests that ins-17 and ins-18 homologues are specifically involved in regulating development and migration in T. canis larvae in host tissues. Conclusion The findings of this study provide a basis for functional explorations of insulin-like peptides, signalling hormones (i.e. DAs) and related nuclear receptors, proposed to link to development and/or parasite-host interactions in T. canis. Elucidating the functional roles of these molecules might contribute to the discovery of novel anthelmintic targets in ascaridoids. Electronic supplementary material The online version of this article (10.1186/s13071-018-3265-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Guangxu Ma
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Tao Wang
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Pasi K Korhonen
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Shuai Nie
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Gavin E Reid
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Andreas J Stroehlein
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Anson V Koehler
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Bill C H Chang
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Andreas Hofmann
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland, 4111, Australia
| | - Neil D Young
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Robin B Gasser
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, 3010, Australia.
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Ma G, Wang T, Korhonen PK, Ang CS, Williamson NA, Young ND, Stroehlein AJ, Hall RS, Koehler AV, Hofmann A, Gasser RB. Molecular alterations during larval development of Haemonchus contortus in vitro are under tight post-transcriptional control. Int J Parasitol 2018; 48:763-772. [PMID: 29792880 DOI: 10.1016/j.ijpara.2018.03.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/20/2018] [Accepted: 03/26/2018] [Indexed: 12/23/2022]
Abstract
In this study, we explored the molecular alterations in the developmental switch from the L3 to the exsheathed L3 (xL3) and to the L4 stage of Haemonchus contortus in vitro using an integrated transcriptomic, proteomic and bioinformatic approach. Totals of 9,754 mRNAs, 88 microRNAs (miRNAs) and 1,591 proteins were identified, and 6,686 miRNA-mRNA pairs inferred in all larval stages studied. Approximately 16% of transcripts in the combined transcriptome (representing all three larval stages) were expressed as proteins, and there were positive correlations (r = 0.39-0.44) between mRNA transcription and protein expression in the three distinct developmental stages of the parasite. Of the predicted targets, 1,019 (27.0%) mRNA transcripts were expressed as proteins, and there was a negative correlation (r = -0.60 to -0.50) in the differential mRNA transcription and protein expression between developmental stages upon pairwise comparison. The changes in transcription (mRNA and miRNA) and protein expression from the free-living to the parasitic life cycle phase of H. contortus related to enrichments in biological pathways associated with metabolism (e.g., carbohydrate and lipid degradation, and amino acid metabolism), environmental information processing (e.g., signal transduction, signalling molecules and interactions) and/or genetic information processing (e.g., transcription and translation). Specifically, fatty acid degradation, steroid hormone biosynthesis and the Rap1 signalling pathway were suppressed, whereas transcription, translation and protein processing in the endoplasmic reticulum were upregulated during the transition from the free-living L3 to the parasitic xL3 and L4 stages of the nematode in vitro. Dominant post-transcriptional regulation was inferred to elicit these changes, and particular miRNAs (e.g., hco-miR-34 and hco-miR-252) appear to play roles in stress responses and/or environmental adaptations during developmental transitions of H. contortus. Taken together, these integrated results provide a comprehensive insight into the developmental biology of this important parasite at the molecular level in vitro. The approach applied here to H. contortus can be readily applied to other parasitic nematodes.
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Affiliation(s)
- Guangxu Ma
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Tao Wang
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Pasi K Korhonen
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Ching-Seng Ang
- The Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Nicholas A Williamson
- The Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Neil D Young
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Andreas J Stroehlein
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Ross S Hall
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Anson V Koehler
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Andreas Hofmann
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia; Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland 4111, Australia
| | - Robin B Gasser
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia.
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Larval crowding accelerates C. elegans development and reduces lifespan. PLoS Genet 2017; 13:e1006717. [PMID: 28394895 PMCID: PMC5402976 DOI: 10.1371/journal.pgen.1006717] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 04/24/2017] [Accepted: 03/27/2017] [Indexed: 11/25/2022] Open
Abstract
Environmental conditions experienced during animal development are thought to have sustained impact on maturation and adult lifespan. Here we show that in the model organism C. elegans developmental rate and adult lifespan depend on larval population density, and that this effect is mediated by excreted small molecules. By using the time point of first egg laying as a marker for full maturity, we found that wildtype hermaphrodites raised under high density conditions developed significantly faster than animals raised in isolation. Population density-dependent acceleration of development (Pdda) was dramatically enhanced in fatty acid β-oxidation mutants that are defective in the biosynthesis of ascarosides, small-molecule signals that induce developmental diapause. In contrast, Pdda is abolished by synthetic ascarosides and steroidal ligands of the nuclear hormone receptor DAF-12. We show that neither ascarosides nor any known steroid hormones are required for Pdda and that another chemical signal mediates this phenotype, in part via the nuclear hormone receptor NHR-8. Our results demonstrate that C. elegans development is regulated by a push-pull mechanism, based on two antagonistic chemical signals: chemosensation of ascarosides slows down development, whereas population-density dependent accumulation of a different chemical signal accelerates development. We further show that the effects of high larval population density persist through adulthood, as C. elegans larvae raised at high densities exhibit significantly reduced adult lifespan and respond differently to exogenous chemical signals compared to larvae raised at low densities, independent of density during adulthood. Our results demonstrate how inter-organismal signaling during development regulates reproductive maturation and longevity. The nematode C. elegans is one of the most highly developed models for the elucidation of conserved mechanisms connecting environmental cues to the regulation of animal lifespan and development. Surprisingly, the effects of larval population density on developmental timing and adult lifespan have not been investigated, although population density is known to affect developmental dynamics and survival in many species. We here describe a novel phenotype in C. elegans: population density-dependent acceleration of development. That high population density would accelerate development is unexpected, since at high population density accumulation of dauer pheromone, a developmental arrest signal, would be expected to slow down development. However, we found that C. elegans development is regulated by a pull-push mechanism, based on at least two different types of pheromone-like signals: the developmental acceleration signal we first describe in this manuscript, and its antagonist, the dauer pheromone, whose chemical make-up has gradually emerged over the past 10 years. We further show that both developmental acceleration and deceleration are mediated by two nuclear hormone receptors that have close mammalian homologs. Finally we demonstrate that larval population density predetermines adult lifespan in C. elegans hermaphrodites, including responses to hormonal stimuli during adulthood.
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Phosphorylated glycosphingolipids essential for cholesterol mobilization in Caenorhabditis elegans. Nat Chem Biol 2017; 13:647-654. [PMID: 28369040 DOI: 10.1038/nchembio.2347] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 01/12/2017] [Indexed: 11/08/2022]
Abstract
The nematode Caenorhabditis elegans requires exogenous cholesterol to survive and its depletion leads to early developmental arrest. Thus, tight regulation of cholesterol storage and distribution within the organism is indispensable. Here, we present a novel class of C. elegans phosphorylated glycosphingolipids, phosphoethanolamine glucosylceramides (PEGCs), capable of rescuing larval arrest induced by sterol starvation. We describe the total synthesis of a major PEGC species and demonstrate that the PEGC synthetic counterpart suppresses the dauer-constitutive phenotype of Niemann-Pick C1 (NPC1) and DAF-7/TGF-β mutant worms caused by impaired intracellular sterol trafficking. PEGC biosynthesis depends on functional NPC1 and TGF-β, indicating that these proteins control larval development at least partly through PEGC. Furthermore, glucosylceramide deficiency dramatically reduced PEGC amounts. However, the resulting developmental arrest could be rescued by oversaturation of food with cholesterol. Taken together, these data show that PEGC is essential for C. elegans development through its regulation of sterol mobilization.
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Gomez-Perez A, Kyryakov P, Burstein MT, Asbah N, Noohi F, Iouk T, Titorenko VI. Empirical Validation of a Hypothesis of the Hormetic Selective Forces Driving the Evolution of Longevity Regulation Mechanisms. Front Genet 2016; 7:216. [PMID: 27999589 PMCID: PMC5138192 DOI: 10.3389/fgene.2016.00216] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 11/24/2016] [Indexed: 12/27/2022] Open
Abstract
Exogenously added lithocholic bile acid and some other bile acids slow down yeast chronological aging by eliciting a hormetic stress response and altering mitochondrial functionality. Unlike animals, yeast cells do not synthesize bile acids. We therefore hypothesized that bile acids released into an ecosystem by animals may act as interspecies chemical signals that generate selective pressure for the evolution of longevity regulation mechanisms in yeast within this ecosystem. To empirically verify our hypothesis, in this study we carried out a three-step process for the selection of long-lived yeast species by a long-term exposure to exogenous lithocholic bile acid. Such experimental evolution yielded 20 long-lived mutants, three of which were capable of sustaining their considerably prolonged chronological lifespans after numerous passages in medium without lithocholic acid. The extended longevity of each of the three long-lived yeast species was a dominant polygenic trait caused by mutations in more than two nuclear genes. Each of the three mutants displayed considerable alterations to the age-related chronology of mitochondrial respiration and showed enhanced resistance to chronic oxidative, thermal, and osmotic stresses. Our findings empirically validate the hypothesis suggesting that hormetic selective forces can drive the evolution of longevity regulation mechanisms within an ecosystem.
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Affiliation(s)
| | - Pavlo Kyryakov
- Department of Biology, Concordia University Montreal, QC, Canada
| | | | - Nimara Asbah
- Department of Biology, Concordia University Montreal, QC, Canada
| | - Forough Noohi
- Department of Biology, Concordia University Montreal, QC, Canada
| | - Tania Iouk
- Department of Biology, Concordia University Montreal, QC, Canada
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Albarqi MMY, Stoltzfus JD, Pilgrim AA, Nolan TJ, Wang Z, Kliewer SA, Mangelsdorf DJ, Lok JB. Regulation of Life Cycle Checkpoints and Developmental Activation of Infective Larvae in Strongyloides stercoralis by Dafachronic Acid. PLoS Pathog 2016; 12:e1005358. [PMID: 26727267 PMCID: PMC4703199 DOI: 10.1371/journal.ppat.1005358] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 12/02/2015] [Indexed: 12/11/2022] Open
Abstract
The complex life cycle of the parasitic nematode Strongyloides stercoralis leads to either developmental arrest of infectious third-stage larvae (iL3) or growth to reproductive adults. In the free-living nematode Caenorhabditis elegans, analogous determination between dauer arrest and reproductive growth is governed by dafachronic acids (DAs), a class of steroid hormones that are ligands for the nuclear hormone receptor DAF-12. Biosynthesis of DAs requires the cytochrome P450 (CYP) DAF-9. We tested the hypothesis that DAs also regulate S. stercoralis development via DAF-12 signaling at three points. First, we found that 1 μM Δ7-DA stimulated 100% of post-parasitic first-stage larvae (L1s) to develop to free-living adults instead of iL3 at 37°C, while 69.4±12.0% (SD) of post-parasitic L1s developed to iL3 in controls. Second, we found that 1 μM Δ7-DA prevented post-free-living iL3 arrest and stimulated 85.2±16.9% of larvae to develop to free-living rhabditiform third- and fourth-stages, compared to 0% in the control. This induction required 24-48 hours of Δ7-DA exposure. Third, we found that the CYP inhibitor ketoconazole prevented iL3 feeding in host-like conditions, with only 5.6±2.9% of iL3 feeding in 40 μM ketoconazole, compared to 98.8±0.4% in the positive control. This inhibition was partially rescued by Δ7-DA, with 71.2±16.4% of iL3 feeding in 400 nM Δ7-DA and 35 μM ketoconazole, providing the first evidence of endogenous DA production in S. stercoralis. We then characterized the 26 CYP-encoding genes in S. stercoralis and identified a homolog with sequence and developmental regulation similar to DAF-9. Overall, these data demonstrate that DAF-12 signaling regulates S. stercoralis development, showing that in the post-parasitic generation, loss of DAF-12 signaling favors iL3 arrest, while increased DAF-12 signaling favors reproductive development; that in the post-free-living generation, absence of DAF-12 signaling is crucial for iL3 arrest; and that endogenous DA production regulates iL3 activation.
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Affiliation(s)
- Mennatallah M. Y. Albarqi
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Biology, Hollins University, Roanoke, Virginia, United States of America
| | - Jonathan D. Stoltzfus
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Biology, Hollins University, Roanoke, Virginia, United States of America
| | - Adeiye A. Pilgrim
- Department of Biology, Hollins University, Roanoke, Virginia, United States of America
| | - Thomas J. Nolan
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Zhu Wang
- Department of Pharmacology, University of Texas Southwest Medical Center, Dallas, Texas, United States of America
| | - Steven A. Kliewer
- Department of Pharmacology, University of Texas Southwest Medical Center, Dallas, Texas, United States of America
- Department of Molecular Biology, University of Texas Southwest Medical Center, Dallas, Texas, United States of America
| | - David J. Mangelsdorf
- Department of Pharmacology, University of Texas Southwest Medical Center, Dallas, Texas, United States of America
- Howard Hughes Medical Institute, University of Texas Southwest Medical Center, Dallas, Texas, United States of America
| | - James B. Lok
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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von Reuss SH, Schroeder FC. Combinatorial chemistry in nematodes: modular assembly of primary metabolism-derived building blocks. Nat Prod Rep 2015; 32:994-1006. [PMID: 26059053 PMCID: PMC4884655 DOI: 10.1039/c5np00042d] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The nematode Caenorhabditis elegans was the first animal to have its genome fully sequenced and has become an important model organism for biomedical research. However, like many other animal model systems, its metabolome remained largely uncharacterized, until recent investigations demonstrated the importance of small molecule-based signalling cascades for virtually every aspect of nematode biology. These studies have revealed that nematodes are amazingly skilled chemists: using simple building blocks from conserved primary metabolism and a strategy of modular assembly, C. elegans and other nematode species create complex molecular architectures to regulate their development and behaviour. These nematode-derived modular metabolites (NDMMs) are based on the dideoxysugars ascarylose or paratose, which serve as scaffolds for attachment of moieties from lipid, amino acid, carbohydrate, citrate, and nucleoside metabolism. Mutant screens and comparative metabolomics based on NMR spectroscopy and MS have so-far revealed several 100 different ascarylose ("ascarosides") and a few paratose ("paratosides") derivatives, many of which represent potent signalling molecules that can be active at femtomolar levels, regulating development, behaviour, body shape, and many other life history traits. NDMM biosynthesis appears to be carefully regulated as assembly of different modules proceeds with very high specificity. Preliminary biosynthetic studies have confirmed the primary metabolism origin of some NDMM building blocks, whereas the mechanisms that underlie their highly specific assembly are not understood. Considering their functions and biosynthetic origin, NDMMs represent a new class of natural products that cannot easily be classified as "primary" or "secondary". We believe that the identification of new variants of primary metabolism-derived structures that serve important signalling functions in C. elegans and other nematodes provides a strong incentive for a comprehensive re-analysis of metabolism in higher animals, including humans.
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Affiliation(s)
- Stephan H. von Reuss
- Max Planck Institute for Chemical Ecology, Department of Bioorganic Chemistry, Jena, Germany
| | - Frank C. Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
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Yim JJ, Bose N, Meyer JM, Sommer RJ, Schroeder FC. Nematode signaling molecules derived from multimodular assembly of primary metabolic building blocks. Org Lett 2015; 17:1648-51. [PMID: 25782998 PMCID: PMC4878434 DOI: 10.1021/acs.orglett.5b00329] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In the nematode model organisms Caenorhabditis elegans and Pristionchus pacificus, a new class of natural products based on modular assembly of primary-metabolism-derived building blocks control organismal development and behavior. We report identification and biological activities of the first pentamodular metabolite, pasa#9, and the 8-oxoadenine-containing npar#3 from P. pacificus. These structures suggest co-option of nucleoside and tryptophan metabolic pathways for the biosynthesis of endogenous metabolite libraries that transcend the dichotomy between "primary" and "secondary" metabolism.
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Affiliation(s)
- Joshua J. Yim
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
- Department for Evolutionary Biology, Max Planck Institute for Developmental Biology, Tubingen 72076, Germany
| | - Neelanjan Bose
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Jan M. Meyer
- Department for Evolutionary Biology, Max Planck Institute for Developmental Biology, Tubingen 72076, Germany
| | - Ralf J. Sommer
- Department for Evolutionary Biology, Max Planck Institute for Developmental Biology, Tubingen 72076, Germany
| | - Frank C. Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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Liu W, Li X, Chen J, Li T, Dong M, Lei X. Site-Selective and Metal-Free Aliphatic CH Oxidation Enabled Synthesis of [5,24,25-D3]-(25S)-Δ7-Dafachronic acid. Chemistry 2015; 21:5345-9. [DOI: 10.1002/chem.201500324] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Indexed: 11/07/2022]
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Reichetzeder C, Chen H, Föller M, Slowinski T, Li J, Chen YP, Lang F, Hocher B. Maternal Vitamin D Deficiency and Fetal Programming - Lessons Learned from Humans and Mice. Kidney Blood Press Res 2014; 39:315-29. [DOI: 10.1159/000355809] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2014] [Indexed: 11/19/2022] Open
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Mechanisms underlying the anti-aging and anti-tumor effects of lithocholic bile acid. Int J Mol Sci 2014; 15:16522-43. [PMID: 25238416 PMCID: PMC4200844 DOI: 10.3390/ijms150916522] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 08/21/2014] [Accepted: 09/11/2014] [Indexed: 12/13/2022] Open
Abstract
Bile acids are cholesterol-derived bioactive lipids that play essential roles in the maintenance of a heathy lifespan. These amphipathic molecules with detergent-like properties display numerous beneficial effects on various longevity- and healthspan-promoting processes in evolutionarily distant organisms. Recent studies revealed that lithocholic bile acid not only causes a considerable lifespan extension in yeast, but also exhibits a substantial cytotoxic effect in cultured cancer cells derived from different tissues and organisms. The molecular and cellular mechanisms underlying the robust anti-aging and anti-tumor effects of lithocholic acid have emerged. This review summarizes the current knowledge of these mechanisms, outlines the most important unanswered questions and suggests directions for future research.
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Niwa R, Niwa YS. Enzymes for ecdysteroid biosynthesis: their biological functions in insects and beyond. Biosci Biotechnol Biochem 2014; 78:1283-92. [DOI: 10.1080/09168451.2014.942250] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Abstract
Steroid hormones are responsible for the coordinated regulation of many aspects of biological processes in multicellular organisms. Since the last century, many studies have identified and characterized steroidogenic enzymes in vertebrates, including mammals. However, much less is known about invertebrate steroidogenic enzymes. In the last 15 years, a number of steroidogenic enzymes and their functions have been characterized in ecdysozoan animals, especially in the fruit fly Drosophila melanogaster. In this review, we summarize the latest knowledge of enzymes crucial for synthesizing ecdysteroids, the principal insect steroid hormones. We also discuss the functional conservation and diversity of ecdysteroidogenic enzymes in other insects and even non-insect species, such as nematodes, vertebrates, and lower eukaryotes.
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Affiliation(s)
- Ryusuke Niwa
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
- Japan Science and Technology Agency, PRESTO, Kawaguchi, Japan
| | - Yuko S Niwa
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
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Judkins JC, Mahanti P, Hoffman J, Yim I, Antebi A, Schroeder FC. A photocleavable masked nuclear-receptor ligand enables temporal control of C. elegans development. Angew Chem Int Ed Engl 2014; 53:2110-3. [PMID: 24453122 PMCID: PMC4016105 DOI: 10.1002/anie.201307465] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Revised: 11/02/2013] [Indexed: 11/10/2022]
Abstract
The development and lifespan of C. elegans are controlled by the nuclear hormone receptor DAF-12, an important model for the vertebrate vitamin D and liver X receptors. As with its mammalian homologues, DAF-12 function is regulated by bile acid-like steroidal ligands; however, tools for investigating their biosynthesis and function in vivo are lacking. A flexible synthesis for DAF-12 ligands and masked ligand derivatives that enable precise temporal control of DAF-12 function was developed. For ligand masking, photocleavable amides of 5-methoxy-N-methyl-2-nitroaniline (MMNA) were introduced. MMNA-masked ligands are bioavailable and after incorporation into the worm, brief UV irradiation can be used to trigger the expression of DAF-12 target genes and initiate development from dauer larvae into adults. The in vivo release of DAF-12 ligands and other small-molecule signals by using photocleavable MMNA-masked ligands will enable functional studies with precise spatial and temporal resolution.
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Judkins JC, Mahanti P, Hoffman JB, Yim I, Antebi A, Schroeder FC. A Photocleavable Masked Nuclear-Receptor Ligand Enables Temporal Control ofC. elegansDevelopment. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201307465] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Flatt T, Amdam GV, Kirkwood TBL, Omholt SW. Life-history evolution and the polyphenic regulation of somatic maintenance and survival. QUARTERLY REVIEW OF BIOLOGY 2013; 88:185-218. [PMID: 24053071 DOI: 10.1086/671484] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Here we discuss life-history evolution from the perspective of adaptive phenotypic plasticity, with a focus on polyphenisms for somatic maintenance and survival. Polyphenisms are adaptive discrete alternative phenotypes that develop in response to changes in the environment. We suggest that dauer larval diapause and its associated adult phenotypes in the nematode (Caenorhabditis elegans), reproductive dormancy in the fruit fly (Drosophila melanogaster) and other insects, and the worker castes of the honey bee (Apis mellifera) are examples of what may be viewed as the polyphenic regulation of somatic maintenance and survival. In these and other cases, the same genotype can--depending upon its environment--express either of two alternative sets of life-history phenotypes that differ markedly with respect to somatic maintenance, survival ability, and thus life span. This plastic modulation of somatic maintenance and survival has traditionally been underappreciated by researchers working on aging and life history. We review the current evidence for such adaptive life-history switches and their molecular regulation and suggest that they are caused by temporally and/or spatially varying, stressful environments that impose diversifying selection, thereby favoring the evolution of plasticity of somatic maintenance and survival under strong regulatory control. By considering somatic maintenance and survivorship from the perspective of adaptive life-history switches, we may gain novel insights into the mechanisms and evolution of aging.
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Affiliation(s)
- Thomas Flatt
- Institut für Populationsgenetik, Vetmeduni Vienna, A-1210 Vienna, Austria.
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Bochkis IM, Shin S, Kaestner KH. Bile acid-induced inflammatory signaling in mice lacking Foxa2 in the liver leads to activation of mTOR and age-onset obesity. Mol Metab 2013; 2:447-56. [PMID: 24327960 DOI: 10.1016/j.molmet.2013.08.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 08/12/2013] [Accepted: 08/15/2013] [Indexed: 12/30/2022] Open
Abstract
Cytokine signaling has been connected to regulation of metabolism and energy balance. Numerous cytokine gene expression changes are stimulated by accumulation of bile acids in livers of young Foxa2 liver-conditional null mice. We hypothesized that bile acid-induced inflammation in young Foxa2 mutants, once chronic, affects metabolic homeostasis. We found that loss of Foxa2 in the liver results in a premature aging phenotype, including significant weight gain, reduced food intake, and decreased energy expenditure. We show that Foxa2 antagonizes the mammalian target of rapamycin (mTOR) pathway, resulting in increased hepatic lipogenesis and adiposity. While much prior work has focused on adipose tissue in obesity, we discovered a novel age-onset obesity phenotype in a model where gene deletion occurs only in the liver, underscoring the importance of the role hepatic lipogenesis plays in the development of obesity.
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Affiliation(s)
- Irina Mikhailovna Bochkis
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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Belfer SJ, Chuang HS, Freedman BL, Yuan J, Norton M, Bau HH, Raizen DM. Caenorhabditis-in-drop array for monitoring C. elegans quiescent behavior. Sleep 2013; 36:689-698G. [PMID: 23633751 DOI: 10.5665/sleep.2628] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES To develop a method, called Caenorhabditis-in-Drop (CiD), encapsulating single worms in aqueous drops, for parallel analysis of behavioral quiescence in C. elegans nematodes. DESIGN We designed, constructed, and tested a device that houses an array of aqueous droplets laden with individual worms. The droplets are separated and covered by immiscible, biocompatible oil. We modeled gas exchange across the aqueous/oil interface and tested the viability of the encapsulated animals. We studied the behavior of wild-type animals; of animals with a loss of function mutation in the cGMP-dependent protein kinase gene egl-4; of animals with a loss of function mutation in the gene kin-2, which encodes a cAMP-dependent protein kinase A regulatory subunit; of animals with a gain-of-function mutation in the gene acy-1, which encodes an adenylate cyclase; and of animals that express high levels of the EGF protein encoded by lin-3. MEASUREMENTS AND RESULTS We used CiD to simultaneously monitor the behavior of 24 worms, a nearly 5-fold improvement over the prior best methodology. In support of our gas exchange models, we found that worms remain viable on the chip for 4 days, past the 12-h period needed for observation, but show reduced longevity to that measured on an agar surface. Measurements of duration of lethargus quiescence and total leth-argus quiescence showed reduced amounts as well as reduced variability relative to prior methods. There was reduced lethargus quiescence in animals that were mutant for kin-2 and for acy-1, supporting a wake-promoting effect of PKA in C. elegans, but no change in lethargus quiescence in egl-4 mutants. There was increased quiescence in animals that expressed kin-2 in the nervous system or over-expressed EGF. CONCLUSIONS CiD is useful for the analysis of behavioral quiescence during lethargus as well as during the adult stage C. elegans. The method is expandable to parallel simultaneous monitoring of hundreds of animals and for other studies of long-term behavior. Using this method, we were successful in measuring, for the first time, quiescence in kin-2(ce179) and in acy-2(ce2) mutants, which are hyperactive. Our observations also highlight the impact of environmental conditions on quiescent behavior and show that longevity is reduced in CiD in comparison to agar surfaces.
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Affiliation(s)
- Samuel J Belfer
- Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
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Samaja GA, Castro O, Alvarez LD, Dansey MV, Escudero DS, Veleiro AS, Pecci A, Burton G. 27-Nor-Δ4-dafachronic acid is a synthetic ligand of Caenorhabditis elegans DAF-12 receptor. Bioorg Med Chem Lett 2013; 23:2893-6. [DOI: 10.1016/j.bmcl.2013.03.071] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 03/11/2013] [Accepted: 03/20/2013] [Indexed: 12/16/2022]
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Abstract
Environments can be ever-changing and stresses are commonplace. In order for organisms to survive, they need to be able to respond to change and adapt to new conditions. Fortunately, many organisms have systems in place that enable dynamic adaptation to immediate stresses and changes within the environment. Much of this cellular response is coordinated by modulating the structure and accessibility of the genome. In eukaryotic cells, the genome is packaged and rolled up by histone proteins to create a series of DNA/histone core structures known as nucleosomes; these are further condensed into chromatin. The degree and nature of the condensation can in turn determine which genes are transcribed. Histones can be modified chemically by a large number of proteins that are thereby responsible for dynamic changes in gene expression. In this Primer we discuss findings from a study published in this issue of PLoS Biology by Weiner et al. that highlight how chromatin structure and chromatin binding proteins alter transcription in response to environmental changes and stresses. Their study reveals the importance of chromatin in mediating the speed and amplitude of stress responses in cells and suggests that chromatin is a critically important component of the cellular response to stress.
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Affiliation(s)
- Karen T. Smith
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Jerry L. Workman
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
- * E-mail:
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