Evolutionary adaptation to environmental and endogenous microbes has shaped the immunity and physiology of multicellular organisms. Convergent genetic studies of innate immunity in mammals and in Drosophila revealed a commonality in the ancient signaling pathways of host defense, motivating me to embark on the molecular genetic analysis of innate immunity in the simple host organism Caenorhabditis elegans. The long-term goal of this project is to understand the molecular mechanisms of host defense in C. elegans, with the anticipation that studies in this simple host organism will shed light on conserved mechanisms of innate immunity and the evolution and physiology of host-microbe interactions. During the last funding period, we have continued to establish the mechanisms of innate immunity in C. elegans, while also extending our work to encompass the integrative physiology of host responses to infection. We discovered a physiological role for the Unfolded Protein Response in innate immune tolerance and defined how polymorphisms in neuronal genes can modulate the behavioral avoidance of pathogenic bacteria, underscoring the role of the nervous system in responses to microbes. We also initiated a study to understand the molecular basis of immunosenescence in C. elegans, the age-associated decline in immune function. Our studies of the C. elegans host have emphasized the influence that microbial pathogens and innate immune activation can have on host physiology. In this renewal application, we bring together a number of insights gained from these studies and turn our attention to how host-microbe interactions influence the physiology of aging and innate immunity. The basic underlying hypothesis of our proposal is that microbial pathogens can influence longevity and immunity of the C. elegans host through the modulation of neuroendocrine signaling pathways. Our preliminary studies have established a requirement for the TGF-ss signaling pathway in the neuroendocrine regulation of host defense. In addition, we observe marked pathogen-induced changes in host neuronal gene expression that we have defined quantitatively using single-molecule fluorescent in situ hybridization methods. We have three aims. First, we will define how the TGF-ss pathway promotes host defense against pathogenic bacteria and assess the role of this pathway during immunosenescence. Second, we will define the host sensory mechanisms involved in responding to changes in the microbial environment and inducing changes in neuronal TGF-ss expression. Third, we will identify the microbial molecule(s) and corresponding genetic determinants that modulate host physiology through changes in TGF-ss-dependent neuroendocrine signals. We anticipate that these studies will illuminate how the microbial environment of the host can modulate diverse aspects of physiology, including processes contributing to aging and longevity.

Public Health Relevance

This proposal describes experiments using the simple host organism, Caenorhabditis elegans, to study evolutionarily conserved mechanisms of innate immunity. Our proposal focuses on how microbial pathogens modulate host immunity and longevity by inducing changes in the expression of secreted hormonal signals by the nervous system. We anticipate that our studies will have implications for the understanding of how the interactions with microbes modulates immunity and aging in diverse hosts, including humans.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM084477-06A1
Application #
8576975
Study Section
Cellular Mechanisms in Aging and Development Study Section (CMAD)
Program Officer
Dunsmore, Sarah
Project Start
2007-09-01
Project End
2017-06-30
Budget Start
2013-08-01
Budget End
2014-06-30
Support Year
6
Fiscal Year
2013
Total Cost
$323,927
Indirect Cost
$106,276
Name
Massachusetts Institute of Technology
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
001425594
City
Cambridge
State
MA
Country
United States
Zip Code
02139
Tillman, Erik J; Richardson, Claire E; Cattie, Douglas J et al. (2018) Endoplasmic Reticulum Homeostasis Is Modulated by the Forkhead Transcription Factor FKH-9 During Infection of Caenorhabditis elegans. Genetics 210:1329-1337
Hilbert, Zoë A; Kim, Dennis H (2018) PDF-1 neuropeptide signaling regulates sexually dimorphic gene expression in shared sensory neurons of C. elegans. Elife 7:
Fletcher, Marissa; Kim, Dennis H (2017) Age-Dependent Neuroendocrine Signaling from Sensory Neurons Modulates the Effect of Dietary Restriction on Longevity of Caenorhabditis elegans. PLoS Genet 13:e1006544
Hilbert, Zoë A; Kim, Dennis H (2017) Sexually dimorphic control of gene expression in sensory neurons regulates decision-making behavior in C. elegans. Elife 6:
Kulalert, Warakorn; Sadeeshkumar, Harini; Zhang, Ying K et al. (2017) Molecular Determinants of the Regulation of Development and Metabolism by Neuronal eIF2? Phosphorylation in Caenorhabditis elegans. Genetics 206:251-263
Meisel, Joshua D; Kim, Dennis H (2016) Inhibition of Lithium-Sensitive Phosphatase BPNT-1 Causes Selective Neuronal Dysfunction in C. elegans. Curr Biol 26:1922-8
Cattie, Douglas J; Richardson, Claire E; Reddy, Kirthi C et al. (2016) Mutations in Nonessential eIF3k and eIF3l Genes Confer Lifespan Extension and Enhanced Resistance to ER Stress in Caenorhabditis elegans. PLoS Genet 12:e1006326
Pagano, Daniel J; Kingston, Elena R; Kim, Dennis H (2015) Tissue expression pattern of PMK-2 p38 MAPK is established by the miR-58 family in C. elegans. PLoS Genet 11:e1004997
Meisel, Joshua D; Panda, Oishika; Mahanti, Parag et al. (2014) Chemosensation of bacterial secondary metabolites modulates neuroendocrine signaling and behavior of C. elegans. Cell 159:267-80
Kulalert, Warakorn; Kim, Dennis H (2013) The unfolded protein response in a pair of sensory neurons promotes entry of C. elegans into dauer diapause. Curr Biol 23:2540-5

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