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Ghosh A, Singh J. Translation initiation or elongation inhibition triggers contrasting effects on Caenorhabditis elegans survival during pathogen infection. mBio 2024:e0248524. [PMID: 39347574 DOI: 10.1128/mbio.02485-24] [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: 08/15/2024] [Accepted: 09/11/2024] [Indexed: 10/01/2024] Open
Abstract
Diverse microbial pathogens are known to attenuate host protein synthesis. Consequently, the host mounts a defense response against protein translation inhibition, leading to increased transcript levels of immune genes. The seemingly paradoxical upregulation of immune gene transcripts in response to blocked protein synthesis suggests that the defense mechanism against translation inhibition may not universally benefit host survival. However, a comprehensive assessment of host survival on pathogens upon blockage of different stages of protein synthesis is currently lacking. Here, we investigate the impact of knockdown of various translation initiation and elongation factors on the survival of Caenorhabditis elegans exposed to Pseudomonas aeruginosa. Intriguingly, we observe opposing effects on C. elegans survival depending on whether translation initiation or elongation is inhibited. While translation initiation inhibition enhances survival, elongation inhibition decreases it. Transcriptomic studies reveal that translation initiation inhibition activates a bZIP transcription factor ZIP-2-dependent innate immune response that protects C. elegans from P. aeruginosa infection. In contrast, inhibiting translation elongation triggers both ZIP-2-dependent and ZIP-2-independent immune responses that, while effective in clearing the infection, are detrimental to the host. Thus, our findings reveal the opposing roles of translation initiation and elongation inhibition in C. elegans survival during P. aeruginosa infection, highlighting distinct transcriptional reprogramming that may underlie these differences. IMPORTANCE Several microbial pathogens target host protein synthesis machinery, potentially limiting the innate immune responses of the host. In response, hosts trigger a defensive response, elevating immune gene transcripts. This counterintuitive response can have either beneficial or harmful effects on host survival. In this study, we conduct a comprehensive analysis of the impact of knocking down various translation initiation and elongation factors on the survival of Caenorhabditis elegans exposed to Pseudomonas aeruginosa. Intriguingly, inhibiting initiation and elongation factors has contrasting effects on C. elegans survival. Inhibiting translation initiation activates immune responses that protect the host from bacterial infection, while inhibiting translation elongation induces aberrant immune responses that, although clear the infection, are detrimental to the host. Our study reveals divergent roles of translation initiation and elongation inhibition in C. elegans survival during P. aeruginosa infection and identifies differential transcriptional reprogramming that could underlie these differences.
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Affiliation(s)
- Annesha Ghosh
- Department of Biological Sciences, Indian Institute of Science Education and Research, Mohali, Punjab, India
| | - Jogender Singh
- Department of Biological Sciences, Indian Institute of Science Education and Research, Mohali, Punjab, India
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Kubra S, Sun M, Dion W, Catak A, Luong H, Wang H, Pan Y, Liu JJ, Ponna A, Sipula I, Jurczak MJ, Liu S, Zhu B. Epigenetic regulation of global proteostasis dynamics by RBBP5 ensures mammalian organismal health. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.13.612812. [PMID: 39314427 PMCID: PMC11419162 DOI: 10.1101/2024.09.13.612812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 09/25/2024]
Abstract
Proteostasis is vital for cellular health, with disruptions leading to pathologies including aging, neurodegeneration and metabolic disorders. Traditionally, proteotoxic stress responses were studied as acute reactions to various noxious factors; however, recent evidence reveals that many proteostasis stress-response genes exhibit ~12-hour ultradian rhythms under physiological conditions in mammals. These rhythms, driven by an XBP1s-dependent 12h oscillator, are crucial for managing proteostasis. By exploring the chromatin landscape of the murine 12h hepatic oscillator, we identified RBBP5, a key subunit of the COMPASS complex writing H3K4me3, as an essential epigenetic regulator of proteostasis. RBBP5 is indispensable for regulating both the hepatic 12h oscillator and transcriptional response to acute proteotoxic stress, acting as a co-activator for proteostasis transcription factor XBP1s. RBBP5 ablation leads to increased sensitivity to proteotoxic stress, chronic inflammation, and hepatic steatosis in mice, along with impaired autophagy and reduced cell survival in vitro. In humans, lower RBBP5 expression is associated with reduced adaptive stress-response gene expression and hepatic steatosis. Our findings establish RBBP5 as a central regulator of proteostasis, essential for maintaining mammalian organismal health.
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Affiliation(s)
- Syeda Kubra
- Aging Institute of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
| | - Michelle Sun
- Aging Institute of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
| | - William Dion
- Aging Institute of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
| | - Ahmet Catak
- Aging Institute of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
| | - Hannah Luong
- Aging Institute of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
| | - Haokun Wang
- Aging Institute of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
| | | | - Jia-Jun Liu
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA, U.S.A
- Organ Pathobiology and Therapeutics Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
| | - Aishwarya Ponna
- Aging Institute of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
| | - Ian Sipula
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
| | - Michael J. Jurczak
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
| | - Silvia Liu
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA, U.S.A
- Organ Pathobiology and Therapeutics Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
| | - Bokai Zhu
- Aging Institute of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA, U.S.A
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
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Hull B, Irby IM, Miller KM, Anderson A, Gardea EA, Sutphin GL. Experimental variables that impact outcomes in Caenorhabditis elegans aging stress response. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.09.574889. [PMID: 38260451 PMCID: PMC10802420 DOI: 10.1101/2024.01.09.574889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Cellular stress is a fundamental component of age-associated disease. Cells encounter various forms of stress - oxidative stress, protein misfolding, DNA damage, etc. - and respond by activating specific, well-defined stress response pathways. As we age, the burden of stress and resulting damage increases while our cells' ability to deal with the consequences becomes diminished due to dysregulation of cellular stress response pathways. Many interventions that extend lifespan activate one or more stress response pathways or allow cells to maintain normal stress response later in life. The nematode Caenorhabditis elegans is a commonly used model for both aging and stress response research. As such, stress response experiments are regularly conducted as part of studies focused on mechanisms of aging in C. elegans. However, experimental design across experiments in the field are highly variable, including stressor dose, age at exposure, culture type (liquid vs. solid), bacterial strain used as a food source, and environmental temperature. These differences can result in different experimental outcomes, making comparison of results between studies challenging. Here we evaluate several experimental variables that are variable in the published literature and find that each can meaningfully alter experimental outcomes for multiple stressors. Our goal is to raise awareness of the issue of experimental variability within the field and suggest a standardized experimental design to serve as a set of guidelines for future experiments. By adopting these guidelines as a starting point, and explicitly noting differences in specific experiments, we aim to promote rigor and reproducibility, ultimately fostering more interpretable and translatable outcomes in geroscience research.
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Zhang L, Zhang J, Ye ZW, Muhammad A, Li L, Culpepper JW, Townsend DM, Tew KD. Adaptive changes in tumor cells in response to reductive stress. Biochem Pharmacol 2024; 219:115929. [PMID: 38000559 PMCID: PMC10895707 DOI: 10.1016/j.bcp.2023.115929] [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: 09/27/2023] [Revised: 11/14/2023] [Accepted: 11/15/2023] [Indexed: 11/26/2023]
Abstract
Reductive stress is characterized by an excess of cellular electron donors and can be linked with various human pathologies including cancer. We developed melanoma cell lines resistant to reductive stress agents: rotenone (ROTR), n-acetyl-L-cysteine, (NACR), or dithiothreitol (DTTR). Resistant cells divided more rapidly and had intracellular homeostatic redox-couple ratios that were shifted towards the reduced state. Resistance caused alterations in general cell morphology, but only ROTR cells had significant changes in mitochondrial morphology with higher numbers that were more isolated, fragmented and swollen, with greater membrane depolarization and decreased numbers of networks. These changes were accompanied by lower basal oxygen consumption and maximal respiration rates. Whole cell flux analyses and mitochondrial function assays showed that NACR and DTTR preferentially utilized tricarboxylic acid (TCA) cycle intermediates, while ROTR used ketone body substrates such as D, L-β-hydroxybutyric acid. NACR and DTTR cells had constitutively decreased levels of reactive oxygen species (ROS), although this was accompanied by activation of nuclear factor erythroid 2-related factor 2 (Nrf2), with concomitant increased expression of the downstream gene products such as glutathione S-transferase P (GSTP). Further adaptations included enhanced expression of endoplasmic reticulum proteins controlling the unfolded protein response (UPR). Although expression patterns of these UPR proteins were distinct between the resistant cells, a trend implied that resistance to reductive stress is accompanied by a constitutively increased UPR phenotype in each line. Overall, tumor cells, although tolerant of oxidative stress, can adapt their energy and survival mechanisms in lethal reductive stress conditions.
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Affiliation(s)
- Leilei Zhang
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, 70 President St., DD410, Charleston, SC 29425, USA
| | - Jie Zhang
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, 70 President St., DD410, Charleston, SC 29425, USA
| | - Zhi-Wei Ye
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, 70 President St., DD410, Charleston, SC 29425, USA
| | - Aslam Muhammad
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, 70 President St., DD410, Charleston, SC 29425, USA
| | - Li Li
- Department of Drug Discovery and Experimental Sciences, Medical University of South Carolina, 274 Calhoun Street MSC 141, Charleston, S.C. 29425-1410, USA
| | - John W Culpepper
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, 70 President St., DD410, Charleston, SC 29425, USA
| | - Danyelle M Townsend
- Department of Drug Discovery and Experimental Sciences, Medical University of South Carolina, 274 Calhoun Street MSC 141, Charleston, S.C. 29425-1410, USA
| | - Kenneth D Tew
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, 70 President St., DD410, Charleston, SC 29425, USA.
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Ravi, Kumar A, Bhattacharyya S, Singh J. Thiol reductive stress activates the hypoxia response pathway. EMBO J 2023; 42:e114093. [PMID: 37902464 PMCID: PMC10646554 DOI: 10.15252/embj.2023114093] [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: 03/22/2023] [Revised: 09/19/2023] [Accepted: 09/20/2023] [Indexed: 10/31/2023] Open
Abstract
Owing to their capability to disrupt the oxidative protein folding environment in the endoplasmic reticulum (ER), thiol antioxidants, such as dithiothreitol (DTT), are used as ER-specific stressors. We recently showed that thiol antioxidants modulate the methionine-homocysteine cycle by upregulating an S-adenosylmethionine-dependent methyltransferase, rips-1, in Caenorhabditis elegans. However, the changes in cellular physiology induced by thiol stress that modulate the methionine-homocysteine cycle remain uncharacterized. Here, using forward genetic screens in C. elegans, we discover that thiol stress enhances rips-1 expression via the hypoxia response pathway. We demonstrate that thiol stress activates the hypoxia response pathway. The activation of the hypoxia response pathway by thiol stress is conserved in human cells. The hypoxia response pathway enhances thiol toxicity via rips-1 expression and confers protection against thiol toxicity via rips-1-independent mechanisms. Finally, we show that DTT might activate the hypoxia response pathway by producing hydrogen sulfide. Our studies reveal an intriguing interaction between thiol-mediated reductive stress and the hypoxia response pathway and challenge the current model that thiol antioxidant DTT disrupts only the ER milieu in the cell.
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Affiliation(s)
- Ravi
- Department of Biological SciencesIndian Institute of Science Education and ResearchMohaliIndia
| | - Ajay Kumar
- Department of BiophysicsPostgraduate Institute of Medical Education and ResearchChandigarhIndia
| | - Shalmoli Bhattacharyya
- Department of BiophysicsPostgraduate Institute of Medical Education and ResearchChandigarhIndia
| | - Jogender Singh
- Department of Biological SciencesIndian Institute of Science Education and ResearchMohaliIndia
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Wang H, Zhang Y, Wang J, Chen Y, Hou T, Zhao Y, Ma Z. The sphinganine C4-hydroxylase FgSur2 regulates sensitivity to azole antifungal agents and virulence of Fusarium graminearum. Microbiol Res 2023; 271:127347. [PMID: 36907072 DOI: 10.1016/j.micres.2023.127347] [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: 01/06/2023] [Revised: 02/19/2023] [Accepted: 02/26/2023] [Indexed: 03/09/2023]
Abstract
Lipid rafts consisting of ergosterol and sphingolipids in the lipid membrane of cells play important roles in various cellular processes. However, the functions of sphingolipids and their synthetic genes in phytopathogenic fungi have not been well understood yet. In this study, we conducted genome-wide searches and carried out systematic gene deletion analysis of the sphingolipid synthesis pathway in Fusarium graminearum, a causal agent of Fusarium head blight of wheat and other cereal crops worldwide. Mycelial growth assays showed that deletion of FgBAR1, FgLAC1, FgSUR2 or FgSCS7 resulted in markedly reduced hyphal growth. Fungicide sensitivity tests showed that the sphinganine C4-hydroxylase gene FgSUR2 deletion mutant (ΔFgSUR2) exhibited significantly increased susceptibility to azole fungicides. In addition, this mutant displayed a remarkable increase in cell membrane permeability. Importantly, ΔFgSUR2 was defective in deoxynivalenol (DON) toxisome formation, leading to dramatically decreased DON biosynthesis. Moreover, the deletion of FgSUR2 resulted in dramatically decreased virulence of the pathogen on host plants. Taken together, these results indicate that FgSUR2 plays an important role in regulating the susceptibility to azoles and virulence of F. graminearum.
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Affiliation(s)
- Haixia Wang
- State Key Laboratory of Rice Biology, and Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Yueqi Zhang
- State Key Laboratory of Rice Biology, and Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Jingrui Wang
- State Key Laboratory of Rice Biology, and Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Yun Chen
- State Key Laboratory of Rice Biology, and Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Tingjun Hou
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Youfu Zhao
- Irrigated Agriculture Research and Extension Center, Department of Plant Pathology, Washington State University, Prosser, WA 99350, USA
| | - Zhonghua Ma
- State Key Laboratory of Rice Biology, and Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.
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