1
|
Yan Y, Shetty M, Harding HP, George G, Zyryanova A, Labbé K, Mafi A, Hao Q, Sidrauski C, Ron D. Substrate recruitment via eIF2γ enhances catalytic efficiency of a holophosphatase that terminates the integrated stress response. Proc Natl Acad Sci U S A 2024; 121:e2320013121. [PMID: 38547060 PMCID: PMC10998612 DOI: 10.1073/pnas.2320013121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 02/16/2024] [Indexed: 04/02/2024] Open
Abstract
Dephosphorylation of pSer51 of the α subunit of translation initiation factor 2 (eIF2αP) terminates signaling in the integrated stress response (ISR). A trimeric mammalian holophosphatase comprised of a protein phosphatase 1 (PP1) catalytic subunit, the conserved C-terminally located ~70 amino acid core of a substrate-specific regulatory subunit (PPP1R15A/GADD34 or PPP1R15B/CReP) and G-actin (an essential cofactor) efficiently dephosphorylate eIF2αP in vitro. Unlike their viral or invertebrate counterparts, with whom they share the conserved 70 residue core, the mammalian PPP1R15s are large proteins of more than 600 residues. Genetic and cellular observations point to a functional role for regions outside the conserved core of mammalian PPP1R15A in dephosphorylating its natural substrate, the eIF2 trimer. We have combined deep learning technology, all-atom molecular dynamics simulations, X-ray crystallography, and biochemistry to uncover binding of the γ subunit of eIF2 to a short helical peptide repeated four times in the functionally important N terminus of human PPP1R15A that extends past its conserved core. Binding entails insertion of Phe and Trp residues that project from one face of an α-helix formed by the conserved repeats of PPP1R15A into a hydrophobic groove exposed on the surface of eIF2γ in the eIF2 trimer. Replacing these conserved Phe and Trp residues with Ala compromises PPP1R15A function in cells and in vitro. These findings suggest mechanisms by which contacts between a distant subunit of eIF2 and elements of PPP1R15A distant to the holophosphatase active site contribute to dephosphorylation of eIF2αP by the core PPP1R15 holophosphatase and to efficient termination of the ISR in mammals.
Collapse
Affiliation(s)
- Yahui Yan
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, CambridgeCB2 0XY, United Kingdom
| | - Maithili Shetty
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, CambridgeCB2 0XY, United Kingdom
| | - Heather P. Harding
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, CambridgeCB2 0XY, United Kingdom
| | - Ginto George
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, CambridgeCB2 0XY, United Kingdom
| | - Alisa Zyryanova
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, CambridgeCB2 0XY, United Kingdom
| | | | | | - Qi Hao
- Calico Life Sciences, South San Francisco, CA94080
| | | | - David Ron
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, CambridgeCB2 0XY, United Kingdom
| |
Collapse
|
2
|
Labbé K, Mookerjee S, Le Vasseur M, Gibbs E, Lerner C, Nunnari J. The modified mitochondrial outer membrane carrier MTCH2 links mitochondrial fusion to lipogenesis. J Cell Biol 2021; 220:e202103122. [PMID: 34586346 PMCID: PMC8496048 DOI: 10.1083/jcb.202103122] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 07/26/2021] [Accepted: 09/01/2021] [Indexed: 01/22/2023] Open
Abstract
Mitochondrial function is integrated with cellular status through the regulation of opposing mitochondrial fusion and division events. Here we uncover a link between mitochondrial dynamics and lipid metabolism by examining the cellular role of mitochondrial carrier homologue 2 (MTCH2). MTCH2 is a modified outer mitochondrial membrane carrier protein implicated in intrinsic cell death and in the in vivo regulation of fatty acid metabolism. Our data indicate that MTCH2 is a selective effector of starvation-induced mitochondrial hyperfusion, a cytoprotective response to nutrient deprivation. We find that MTCH2 stimulates mitochondrial fusion in a manner dependent on the bioactive lipogenesis intermediate lysophosphatidic acid. We propose that MTCH2 monitors flux through the lipogenesis pathway and transmits this information to the mitochondrial fusion machinery to promote mitochondrial elongation, enhanced energy production, and cellular survival under homeostatic and starvation conditions. These findings will help resolve the roles of MTCH2 and mitochondria in tissue-specific lipid metabolism in animals.
Collapse
Affiliation(s)
- Katherine Labbé
- The Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, Davis, CA
| | - Shona Mookerjee
- Touro University California, College of Pharmacy, Vallejo, CA
- The Buck Institute for Research on Aging, Novato, CA
| | - Maxence Le Vasseur
- The Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, Davis, CA
| | - Eddy Gibbs
- The Buck Institute for Research on Aging, Novato, CA
| | - Chad Lerner
- The Buck Institute for Research on Aging, Novato, CA
| | - Jodi Nunnari
- The Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, Davis, CA
| |
Collapse
|
3
|
Affiliation(s)
- Katherine Labbé
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616; , ,
| | - Andrew Murley
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616; , ,
| | - Jodi Nunnari
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616; , ,
| |
Collapse
|
4
|
Rodrigue-Gervais IG, Labbé K, Dagenais M, Dupaul-Chicoine J, Champagne C, Morizot A, Skeldon A, Brincks EL, Vidal SM, Griffith TS, Saleh M. Cellular inhibitor of apoptosis protein cIAP2 protects against pulmonary tissue necrosis during influenza virus infection to promote host survival. Cell Host Microbe 2014; 15:23-35. [PMID: 24439895 DOI: 10.1016/j.chom.2013.12.003] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 11/10/2013] [Accepted: 12/10/2013] [Indexed: 12/22/2022]
Abstract
Cellular inhibitors of apoptosis proteins (cIAPs) are essential regulators of cell death and immunity. The corresponding contributions of IAPs to infectious disease outcomes are relatively unexplored. We find that mice deficient in cIAP2 exhibit increased susceptibility and mortality to influenza A virus infection. The lethality was not due to impaired antiviral immune functions, but rather because of death-receptor-induced programmed necrosis of airway epithelial cells that led to severe bronchiole epithelial degeneration, despite control of viral replication. Pharmacological inhibition of RIPK1 or genetic deletion of Ripk3, both kinases involved in programmed necrosis, rescued cIAP2-deficient mice from influenza-induced lethality. Genetic deletion of the death receptor agonists Fas ligand or TRAIL from the hematopoietic compartment also reversed the susceptibility of cIAP2-deficient mice. Thus, cIAP2-dependent antagonism of RIPK3-mediated programmed necrosis critically protects the host from influenza infection through maintenance of pulmonary tissue homeostasis rather than through pathogen control by the immune system.
Collapse
Affiliation(s)
| | - Katherine Labbé
- Department of Microbiology and Immunology, McGill University, Montréal, QC H3A 1B1, Canada
| | - Maryse Dagenais
- Department of Biochemistry, McGill University, Montréal, QC H3A 1B1, Canada
| | | | - Claudia Champagne
- Department of Medicine, McGill University, Montréal, QC H3A 1B1, Canada
| | - Alexandre Morizot
- Department of Medicine, McGill University, Montréal, QC H3A 1B1, Canada
| | - Alexander Skeldon
- Department of Biochemistry, McGill University, Montréal, QC H3A 1B1, Canada
| | - Erik L Brincks
- Department of Urology, Center for Immunology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Silvia M Vidal
- Department of Human Genetics, McGill University, Montréal, QC H3A 1B1, Canada
| | - Thomas S Griffith
- Department of Urology, Center for Immunology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Maya Saleh
- Department of Medicine, McGill University, Montréal, QC H3A 1B1, Canada; Department of Microbiology and Immunology, McGill University, Montréal, QC H3A 1B1, Canada; Department of Biochemistry, McGill University, Montréal, QC H3A 1B1, Canada.
| |
Collapse
|
5
|
Labbé K, McIntire CR, Doiron K, Leblanc PM, Saleh M. Cellular inhibitors of apoptosis proteins cIAP1 and cIAP2 are required for efficient caspase-1 activation by the inflammasome. Immunity 2012; 35:897-907. [PMID: 22195745 DOI: 10.1016/j.immuni.2011.10.016] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 10/05/2011] [Accepted: 10/21/2011] [Indexed: 01/05/2023]
Abstract
Pathogen and danger recognition by the inflammasome activates inflammatory caspases that mediate inflammation and cell death. The cellular inhibitor of apoptosis proteins (cIAPs) function in apoptosis and innate immunity, but their role in modulating the inflammasome and the inflammatory caspases is unknown. Here we report that the cIAPs are critical effectors of the inflammasome and are required for efficient caspase-1 activation. cIAP1, cIAP2, and the adaptor protein TRAF2 interacted with caspase-1-containing complexes and mediated the activating nondegradative K63-linked polyubiquitination of caspase-1. Deficiency in cIAP1 (encoded by Birc2) or cIAP2 (Birc3) impaired caspase-1 activation after spontaneous or agonist-induced inflammasome assembly, and Birc2(-/-) or Birc3(-/-) mice or mice administered with an IAP antagonist had a dampened response to inflammasome agonists and were resistant to peritonitis. Our results describe a role for the cIAPs in innate immunity and further demonstrate the evolutionary conservation between cell death and inflammation mechanisms.
Collapse
Affiliation(s)
- Katherine Labbé
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3G 0B1, Canada
| | | | | | | | | |
Collapse
|
6
|
LeBlanc PM, Labbé K, Yeretssian G, Saleh M. PS3-35 Caspase-1 processes high mobility group box 1 and is required for its release during infection and septic shock. Cytokine 2010. [DOI: 10.1016/j.cyto.2010.07.374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
7
|
Labbé K, Miu J, Yeretssian G, Serghides L, Tam M, Finney CA, Erdman LK, Goulet ML, Kain KC, Stevenson MM, Saleh M. Caspase-12 dampens the immune response to malaria independently of the inflammasome by targeting NF-kappaB signaling. J Immunol 2010; 185:5495-502. [PMID: 20876354 DOI: 10.4049/jimmunol.1002517] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pathogen sensing by the inflammasome activates inflammatory caspases that mediate inflammation and cell death. Caspase-12 antagonizes the inflammasome and NF-κB and is associated with susceptibility to bacterial sepsis. A single-nucleotide polymorphism (T(125)C) in human Casp12 restricts its expression to Africa, Southeast Asia, and South America. Here, we investigated the role of caspase-12 in the control of parasite replication and pathogenesis in malaria and report that caspase-12 dampened parasite clearance in blood-stage malaria and modulated susceptibility to cerebral malaria. This response was independent of the caspase-1 inflammasome, as casp1(-/-) mice were indistinguishable from wild-type animals in response to malaria, but dependent on enhanced NF-κB activation. Mechanistically, caspase-12 competed with NEMO for association with IκB kinase-α/β, effectively preventing the formation of the IκB kinase complex and inhibiting downstream transcriptional activation by NF-κB. Systemic inhibition of NF-κB or Ab neutralization of IFN-γ reversed the increased resistance of casp12(-/-) mice to blood-stage malaria infection.
Collapse
Affiliation(s)
- Katherine Labbé
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Bertrand MJM, Doiron K, Labbé K, Korneluk RG, Barker PA, Saleh M. Cellular inhibitors of apoptosis cIAP1 and cIAP2 are required for innate immunity signaling by the pattern recognition receptors NOD1 and NOD2. Immunity 2009; 30:789-801. [PMID: 19464198 DOI: 10.1016/j.immuni.2009.04.011] [Citation(s) in RCA: 264] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 02/09/2009] [Accepted: 04/08/2009] [Indexed: 01/07/2023]
Abstract
Cellular inhibitor of apoptosis proteins (cIAPs) block apoptosis, but their physiological functions are still under investigation. Here, we report that cIAP1 and cIAP2 are E3 ubiquitin ligases that are required for receptor-interacting protein 2 (RIP2) ubiquitination and for nucleotide-binding and oligomerization (NOD) signaling. Macrophages derived from Birc2(-/-) or Birc3(-/-) mice, or colonocytes depleted of cIAP1 or cIAP2 by RNAi, were defective in NOD signaling and displayed sharp attenuation of cytokine and chemokine production. This blunted response was observed in vivo when Birc2(-/-) and Birc3(-/-) mice were challenged with NOD agonists. Defects in NOD2 signaling are associated with Crohn's disease, and muramyl dipeptide (MDP) activation of NOD2 signaling protects mice from experimental colitis. Here, we show that administration of MDP protected wild-type but not Ripk2(-/-) or Birc3(-/-) mice from colitis, confirming the role of the cIAPs in NOD2 signaling in vivo. This discovery provides therapeutic opportunities in the treatment of NOD-dependent immunologic and inflammatory diseases.
Collapse
|
9
|
Labbé K, Miu J, Tam M, Stevenson M, Saleh M. 55 Inflammatory caspases modulate host response to malaria. Cytokine 2008. [DOI: 10.1016/j.cyto.2008.07.096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
10
|
Abstract
Cell death and innate immunity are ancient evolutionary conserved processes that utilize a dazzling number of related molecular effectors and parallel signal transduction mechanisms. The investigation of the molecular mechanisms linking the sensing of a danger signal (pathogens or tissue damage) to the induction of an inflammatory response has witnessed a renaissance in the last few years. This was initiated by the identification of pattern recognition receptors (PRRs), including Toll-like receptors (TLRs) and more recently cytosolic Nod-like receptors (NLRs), that brought innate immunity to center stage and opened the field to the study of signal transduction pathways, adaptors and central effectors linked to PRRs. This led to the characterization of the inflammasome, a macromolecular complex, scaffolded by NLRs, that recruits and activates inflammatory caspases, which are essential effectors in inflammation and cell death responses. In this review, we describe the molecular pathways of cell death and innate immunity with a focus on recent advancements in both fields and an emphasis on the striking analogies between NLR innate immunity and mitochondrial apoptosis pathways.
Collapse
Affiliation(s)
- Garabet Yeretssian
- Department of Medicine, Division of Critical Care, and Centre for the Study of Host Resistance, McGill University, Montreal, Que., Canada
| | | | | |
Collapse
|