1
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Bourne CM, Taabazuing CY. Harnessing Pyroptosis for Cancer Immunotherapy. Cells 2024; 13:346. [PMID: 38391959 PMCID: PMC10886719 DOI: 10.3390/cells13040346] [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: 12/31/2023] [Revised: 02/09/2024] [Accepted: 02/13/2024] [Indexed: 02/24/2024] Open
Abstract
Cancer immunotherapy is a novel pillar of cancer treatment that harnesses the immune system to fight tumors and generally results in robust antitumor immunity. Although immunotherapy has achieved remarkable clinical success for some patients, many patients do not respond, underscoring the need to develop new strategies to promote antitumor immunity. Pyroptosis is an immunostimulatory type of regulated cell death that activates the innate immune system. A hallmark of pyroptosis is the release of intracellular contents such as cytokines, alarmins, and chemokines that can stimulate adaptive immune activation. Recent studies suggest that pyroptosis promotes antitumor immunity. Here, we review the mechanisms by which pyroptosis can be induced and highlight new strategies to induce pyroptosis in cancer cells for antitumor defense. We discuss how pyroptosis modulates the tumor microenvironment to stimulate adaptive immunity and promote antitumor immunity. We also suggest research areas to focus on for continued development of pyroptosis as an anticancer treatment. Pyroptosis-based anticancer therapies offer a promising new avenue for treating immunologically 'cold' tumors.
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Affiliation(s)
| | - Cornelius Y. Taabazuing
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA;
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2
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Exconde PM, Hernandez-Chavez C, Bourne CM, Richards RM, Bray MB, Lopez JL, Srivastava T, Egan MS, Zhang J, Yoo W, Shin S, Discher BM, Taabazuing CY. The tetrapeptide sequence of IL-18 and IL-1β regulates their recruitment and activation by inflammatory caspases. Cell Rep 2023; 42:113581. [PMID: 38103201 DOI: 10.1016/j.celrep.2023.113581] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 08/24/2023] [Accepted: 11/29/2023] [Indexed: 12/18/2023] Open
Abstract
Inflammasomes are multiprotein signaling complexes that activate the innate immune system. Canonical inflammasomes recruit and activate caspase-1, which then cleaves and activates IL-1β and IL-18, as well as gasdermin D (GSDMD) to induce pyroptosis. In contrast, non-canonical inflammasomes, caspases-4/-5 (CASP4/5) in humans and caspase-11 (CASP11) in mice, are known to cleave GSDMD, but their role in direct processing of other substrates besides GSDMD has remained unknown. Here, we show that CASP4/5 but not CASP11 can directly cleave and activate IL-18. However, CASP4/5/11 can all cleave IL-1β to generate a 27-kDa fragment that deactivates IL-1β signaling. Mechanistically, we demonstrate that the sequence identity of the tetrapeptide sequence adjacent to the caspase cleavage site regulates IL-18 and IL-1β recruitment and activation. Altogether, we have identified new substrates of the non-canonical inflammasomes and reveal key mechanistic details regulating inflammation that may aid in developing new therapeutics for immune-related disorders.
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Affiliation(s)
- Patrick M Exconde
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Claudia Hernandez-Chavez
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Christopher M Bourne
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Rachel M Richards
- Department of Microbiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Mark B Bray
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Jan L Lopez
- Department of Biology, Boston University, Boston, MA, USA
| | - Tamanna Srivastava
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Marisa S Egan
- Department of Microbiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Jenna Zhang
- Department of Microbiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - William Yoo
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Sunny Shin
- Department of Microbiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Bohdana M Discher
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Cornelius Y Taabazuing
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
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3
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Martin CB, Taabazuing CY, Knapp MJ. Dynamic Domain Links Substrate Binding and Catalysis in the Factor-Inhibiting-HIF-1. Biochemistry 2023; 62:2442-2449. [PMID: 37526986 DOI: 10.1021/acs.biochem.3c00231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023]
Abstract
The interplay between active-site chemistry and functionally relevant enzyme motions can provide useful insights into selective enzyme modulation. Modulation of the hypoxia-sensing function of factor-inhibiting-HIF-1 (FIH) enzyme is a potential therapeutic strategy in disease states such as ischemia and cancer. The hypoxia-sensing function of FIH relies in major part on the tight coupling of the first half of the catalytic mechanism which involves O2 activation and eventual succinate production to the second half which involves HIF-1α/CTAD substrate hydroxylation. In this study, we demonstrate the role of a loop hinge domain in FIH (FIH102-118) called the 100s loop in maintaining this particular tight coupling. Molecular dynamics patterns from Gaussian Network Model (iGNM) database analysis of FIH identified the 100s loop as one dynamic domain containing a hinge residue (Tyr102) with a potential substrate positioning role. Enzymological and biophysical studies of the 100s loop point mutants revealed altered enzyme kinetics with the exception of the conservative FIH mutant Y102F, which suggests a sterics-related role for this residue. Removal of the bulk of Tyr102 (Y102A) resulted in succinate production, autohydroxylation, and an O2 binding environment comparable to wild-type FIH. However, the HIF-1α/CTAD substrate hydroxylation of this mutant was significantly reduced which implies that (1) the FIH loop hinge residue Tyr102 does not affect O2 activation, (2) the stacking steric interaction of Tyr102 is important in substrate positioning for productive hydroxylation, and (3) Tyr102 is important for the synchronization of O2 activation and substrate hydroxylation.
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Affiliation(s)
- Cristina B Martin
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Cornelius Y Taabazuing
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Michael J Knapp
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
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4
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Ransey E, Brookens S, Beasley HK, Marshall A, Marlin BJ, Rodriguez-Aliaga P, Headley CA, Wanjalla C, Vazquez AD, Murray S, Damo S, Taabazuing CY, Hinton A. A Practical Guide to Graduate School Interviewing for Historically Excluded Individuals. Am J Physiol Heart Circ Physiol 2023; 324:H786-H790. [PMID: 37027327 DOI: 10.1152/ajpheart.00123.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
Affiliation(s)
- Elizabeth Ransey
- Dept. of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, United States
| | - Shawna Brookens
- Department of Pharmacology, University of Pennsylvania, Philadephia, PA, United States
| | - Heather K Beasley
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, United States
| | - Andrea Marshall
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, United States
| | - Bianca J Marlin
- Mortimer B. Zuckerman Mind Brain and Behavior Institute, Columbia University, New York, NY, United States
- Department of Psychology, Columbia University, New York, NY, United States
- Department of Neuroscience, Columbia University, New York, NY, United States
| | | | - Colwyn Ansel Headley
- Department of Cardiovascular Medicine, Stanford University, Stanford, CA, United States
| | - Celestine Wanjalla
- Department of Medicine, Division of Infectious Diseases, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Arnaldo Diaz Vazquez
- Department of Biomedical Sciences, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Sandra Murray
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Steven Damo
- Department of Life and Physical Sciences, Fisk University, Nashville, TN, United States
- Center for Structural Biology, Vanderbilt University, Nashville, TN, United States
| | - Cornelius Y Taabazuing
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA, United States
| | - Antentor Hinton
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, United States
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5
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Exconde PM, Hernandez-Chavez C, Bray MB, Lopez JL, Srivastava T, Egan MS, Zhang J, Shin S, Discher BM, Taabazuing CY. The tetrapeptide sequence of IL-1β regulates its recruitment and activation by inflammatory caspases. bioRxiv 2023:2023.02.16.528859. [PMID: 36824844 PMCID: PMC9949112 DOI: 10.1101/2023.02.16.528859] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
The mammalian innate immune system uses germline-encoded cytosolic pattern-recognition receptors (PRRs) to detect intracellular danger signals. At least six of these PRRs are known to form multiprotein complexes called inflammasomes which activate cysteine proteases known as caspases. Canonical inflammasomes recruit and activate caspase-1 (CASP1), which in turn cleaves and activates inflammatory cytokines such as IL-1β and IL-18, as well as the pore forming protein, gasdermin D (GSDMD), to induce pyroptotic cell death. In contrast, non-canonical inflammasomes, caspases-4/-5 (CASP4/5) in humans and caspase-11 (CASP11) in mice, are activated by intracellular LPS to cleave GSDMD, but their role in direct processing of inflammatory cytokines has not been established. Here we show that active CASP4/5 directly cleave IL-18 to generate the active species. Surprisingly, we also discovered that CASP4/5/11 cleave IL-1β at D27 to generate a 27 kDa fragment that is predicted to be inactive and cannot signal to the IL-1 receptor. Mechanistically, we discovered that the sequence identity of the P4-P1 tetrapeptide sequence adjacent to the caspase cleavage site (D116) regulates the recruitment and processing of IL-1β by inflammatory caspases to generate the bioactive species. Thus, we have identified new substrates of the non-canonical inflammasomes and reveal key mechanistic details regulating inflammation.
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Affiliation(s)
- Patrick M. Exconde
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Claudia Hernandez-Chavez
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Mark B. Bray
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Jan L. Lopez
- Present address: Department of Biology, Boston University, Boston, Massachusetts, USA
| | - Tamanna Srivastava
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Marisa S. Egan
- Department of Microbiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Jenna Zhang
- Department of Microbiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Sunny Shin
- Department of Microbiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Bohdana M. Discher
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Cornelius Y. Taabazuing
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
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6
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Chui AJ, Griswold AR, Taabazuing CY, Orth EL, Gai K, Rao SD, Ball DP, Hsiao JC, Bachovchin DA. Activation of the CARD8 Inflammasome Requires a Disordered Region. Cell Rep 2020; 33:108264. [PMID: 33053349 PMCID: PMC7594595 DOI: 10.1016/j.celrep.2020.108264] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 06/25/2020] [Accepted: 09/22/2020] [Indexed: 12/23/2022] Open
Abstract
Several cytosolic pattern-recognition receptors (PRRs) form multiprotein complexes called canonical inflammasomes in response to intracellular danger signals. Canonical inflammasomes recruit and activate caspase-1 (CASP1), which in turn cleaves and activates inflammatory cytokines and gasdermin D (GSDMD), inducing pyroptotic cell death. Inhibitors of the dipeptidyl peptidases DPP8 and DPP9 (DPP8/9) activate both the human NLRP1 and CARD8 inflammasomes. NLRP1 and CARD8 have different N-terminal regions but have similar C-terminal regions that undergo autoproteolysis to generate two non-covalently associated fragments. Here, we show that DPP8/9 inhibition activates a proteasomal degradation pathway that targets disordered and misfolded proteins for destruction. CARD8’s N terminus contains a disordered region of ~160 amino acids that is recognized and destroyed by this degradation pathway, thereby freeing its C-terminal fragment to activate CASP1 and induce pyroptosis. Thus, CARD8 serves as an alarm to signal the activation of a degradation pathway for disordered and misfolded proteins. Inflammasomes are multiprotein complexes that detect intracellular danger signals and stimulate powerful immune responses. DPP8/9 inhibitors activate the CARD8 inflammasome through an unknown mechanism. Here, Chui et al. show that DPP8/9 inhibitors induce the degradation of many disordered and misfolded proteins. CARD8 has an N-terminal disordered region that is degraded upon DPP8/9 inhibition, triggering inflammasome formation.
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Affiliation(s)
- Ashley J Chui
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Andrew R Griswold
- Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10065, USA
| | - Cornelius Y Taabazuing
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Elizabeth L Orth
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Kuo Gai
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Sahana D Rao
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Daniel P Ball
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Jeffrey C Hsiao
- Pharmacology Program of the Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Daniel A Bachovchin
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Pharmacology Program of the Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
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7
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Abstract
Inflammasomes are multiprotein complexes that activate inflammatory cytokines and induce pyroptosis in response to intracellular danger-associated signals. NLRP1 and CARD8 are related germline-encoded pattern recognition receptors that form inflammasomes, but their activation mechanisms and biological purposes have not yet been fully established. Both NLRP1 and CARD8 undergo post-translational autoproteolysis to generate two non-covalently associated polypeptide chains. NLRP1 and CARD8 activators induce the proteasome-mediated destruction of the N-terminal fragment, liberating the C-terminal fragment to form an inflammasome. Here, we review the danger-associated stimuli that have been reported to activate NLRP1 and/or CARD8, including anthrax lethal toxin, Toxoplasma gondii, Shigella flexneri and the small molecule DPP8/9 inhibitor Val-boroPro, focusing on recent mechanistic insights and highlighting unresolved questions. In addition, we discuss the recently identified disease-associated mutations in NLRP1 and CARD8, the potential role that DPP9's protein structure plays in inflammasome regulation, and the emerging link between NLRP1 and metabolism. Finally, we summarize all of this latest research and consider the possible biological purposes of these enigmatic inflammasomes.
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Affiliation(s)
| | - Andrew R Griswold
- Weill Cornell, Rockefeller, Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY, USA.,Pharmacology Program of the Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Daniel A Bachovchin
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Pharmacology Program of the Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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8
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Ball DP, Taabazuing CY, Griswold AR, Orth EL, Rao SD, Kotliar IB, Vostal LE, Johnson DC, Bachovchin DA. Caspase-1 interdomain linker cleavage is required for pyroptosis. Life Sci Alliance 2020; 3:3/3/e202000664. [PMID: 32051255 PMCID: PMC7025033 DOI: 10.26508/lsa.202000664] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/03/2020] [Accepted: 02/04/2020] [Indexed: 01/02/2023] Open
Abstract
Pathogen-related signals induce a number of cytosolic pattern-recognition receptors (PRRs) to form canonical inflammasomes, which activate pro-caspase-1 and trigger pyroptotic cell death. All well-studied inflammasome-forming PRRs oligomerize with the adapter protein ASC (apoptosis-associated speck-like protein containing a CARD) to generate a large structure in the cytosol, which induces the dimerization, autoproteolysis, and activation of the pro-caspase-1 zymogen. However, several PRRs can also directly interact with pro-caspase-1 without ASC, forming smaller "ASC-independent" inflammasomes. It is currently thought that little, if any, pro-caspase-1 autoproteolysis occurs during, and is not required for, ASC-independent inflammasome signaling. Here, we show that the related human PRRs NLRP1 and CARD8 exclusively form ASC-dependent and ASC-independent inflammasomes, respectively, identifying CARD8 as the first canonical inflammasome-forming PRR that does not form an ASC-containing signaling platform. Despite their different structures, we discovered that both the NLRP1 and CARD8 inflammasomes require pro-caspase-1 autoproteolysis between the small and large catalytic subunits to induce pyroptosis. Thus, pro-caspase-1 self-cleavage is a required regulatory step for pyroptosis induced by human canonical inflammasomes.
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Affiliation(s)
- Daniel P Ball
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | | | - Andrew R Griswold
- Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY, USA
| | - Elizabeth L Orth
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Sahana D Rao
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Ilana B Kotliar
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Lauren E Vostal
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Darren C Johnson
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Daniel A Bachovchin
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA .,Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Pharmacology Program of the Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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9
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Griswold AR, Ball DP, Bhattacharjee A, Chui AJ, Rao SD, Taabazuing CY, Bachovchin DA. DPP9's Enzymatic Activity and Not Its Binding to CARD8 Inhibits Inflammasome Activation. ACS Chem Biol 2019; 14:2424-2429. [PMID: 31525884 PMCID: PMC6862324 DOI: 10.1021/acschembio.9b00462] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
![]()
Inflammasomes
are multiprotein complexes formed in response to
pathogens. NLRP1 and CARD8 are related proteins that form inflammasomes,
but the pathogen-associated signal(s) and the molecular mechanisms
controlling their activation have not been established. Inhibitors
of the serine dipeptidyl peptidases DPP8 and DPP9 (DPP8/9) activate
both NLRP1 and CARD8. Interestingly, DPP9 binds directly to NLRP1
and CARD8, and this interaction may contribute to the inhibition of
NLRP1. Here, we use activity-based probes, reconstituted inflammasome
assays, and mass spectrometry-based proteomics to further investigate
the DPP9–CARD8 interaction. We show that the DPP9–CARD8
interaction, unlike the DPP9–NLRP1 interaction, is not disrupted
by DPP9 inhibitors or CARD8 mutations that block autoproteolysis.
Moreover, wild-type, but not catalytically inactive mutant, DPP9 rescues
CARD8-mediated cell death in DPP9 knockout cells.
Together, this work reveals that DPP9’s catalytic activity
and not its binding to CARD8 restrains the CARD8 inflammasome and
thus suggests the binding interaction likely serves some other biological
purpose.
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Affiliation(s)
- Andrew R. Griswold
- Tri-Institutional M.D.−Ph.D. Program, Memorial Sloan Kettering Cancer Center, Rockefeller University, Weill Cornell Medical College, New York, New York 10065, United States
- Pharmacology Program, Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Daniel P. Ball
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Abir Bhattacharjee
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Ashley J. Chui
- Tri-Institutional Ph.D. Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Sahana D. Rao
- Tri-Institutional Ph.D. Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Cornelius Y. Taabazuing
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Daniel A. Bachovchin
- Pharmacology Program, Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
- Tri-Institutional Ph.D. Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
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10
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Chui AJ, Okondo MC, Rao SD, Gai K, Griswold AR, Johnson DC, Ball DP, Taabazuing CY, Orth EL, Vittimberga BA, Bachovchin DA. N-terminal degradation activates the NLRP1B inflammasome. Science 2019; 364:82-85. [PMID: 30872531 PMCID: PMC6610862 DOI: 10.1126/science.aau1208] [Citation(s) in RCA: 192] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 11/02/2018] [Accepted: 03/05/2019] [Indexed: 12/29/2022]
Abstract
Intracellular pathogens and danger signals trigger the formation of inflammasomes, which activate inflammatory caspases and induce pyroptosis. The anthrax lethal factor metalloprotease and small-molecule DPP8/9 inhibitors both activate the NLRP1B inflammasome, but the molecular mechanism of NLRP1B activation is unknown. In this study, we used genome-wide CRISPR-Cas9 knockout screens to identify genes required for NLRP1B-mediated pyroptosis. We discovered that lethal factor induces cell death via the N-end rule proteasomal degradation pathway. Lethal factor directly cleaves NLRP1B, inducing the N-end rule-mediated degradation of the NLRP1B N terminus and freeing the NLRP1B C terminus to activate caspase-1. DPP8/9 inhibitors also induce proteasomal degradation of the NLRP1B N terminus but not via the N-end rule pathway. Thus, N-terminal degradation is the common activation mechanism of this innate immune sensor.
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Affiliation(s)
- Ashley J Chui
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Marian C Okondo
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Sahana D Rao
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Kuo Gai
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Andrew R Griswold
- Pharmacology Program of the Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Darren C Johnson
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Daniel P Ball
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Cornelius Y Taabazuing
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Elizabeth L Orth
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Brooke A Vittimberga
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Daniel A Bachovchin
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
- Pharmacology Program of the Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
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11
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Johnson DC, Taabazuing CY, Okondo MC, Chui AJ, Rao SD, Brown FC, Reed C, Peguero E, de Stanchina E, Kentsis A, Bachovchin DA. DPP8/DPP9 inhibitor-induced pyroptosis for treatment of acute myeloid leukemia. Nat Med 2018; 24:1151-1156. [PMID: 29967349 PMCID: PMC6082709 DOI: 10.1038/s41591-018-0082-y] [Citation(s) in RCA: 216] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 04/30/2018] [Indexed: 12/26/2022]
Abstract
Small-molecule inhibitors of the serine dipeptidases DPP8 and DPP9 (DPP8/9) induce a lytic form of cell death called pyroptosis in mouse and human monocytes and macrophages1,2. In mouse myeloid cells, Dpp8/9 inhibition activates the inflammasome sensor Nlrp1b, which in turn activates pro-caspase-1 to mediate cell death3, but the mechanism of DPP8/9 inhibitor-induced pyroptosis in human myeloid cells is not yet known. Here we show that the CARD-containing protein CARD8 mediates DPP8/9 inhibitor-induced pro-caspase-1-dependent pyroptosis in human myeloid cells. We further show that DPP8/9 inhibitors induce pyroptosis in the majority of human acute myeloid leukemia (AML) cell lines and primary AML samples, but not in cells from many other lineages, and that these inhibitors inhibit human AML progression in mouse models. Overall, this work identifies an activator of CARD8 in human cells and indicates that its activation by small-molecule DPP8/9 inhibitors represents a new potential therapeutic strategy for AML.
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Affiliation(s)
- Darren C Johnson
- Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | | | - Marian C Okondo
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Ashley J Chui
- Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Sahana D Rao
- Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Fiona C Brown
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Casie Reed
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Elizabeth Peguero
- Antitumor Assessment Facility, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Elisa de Stanchina
- Antitumor Assessment Facility, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Alex Kentsis
- Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Department of Pediatrics, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Pharmacology Program of the Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Daniel A Bachovchin
- Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA. .,Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA. .,Pharmacology Program of the Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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12
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Okondo MC, Rao SD, Taabazuing CY, Chui AJ, Poplawski SE, Johnson DC, Bachovchin DA. Inhibition of Dpp8/9 Activates the Nlrp1b Inflammasome. Cell Chem Biol 2018; 25:262-267.e5. [PMID: 29396289 DOI: 10.1016/j.chembiol.2017.12.013] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 12/13/2017] [Accepted: 12/22/2017] [Indexed: 12/26/2022]
Abstract
Val-boroPro (PT-100, Talabostat) induces powerful anti-tumor immune responses in syngeneic cancer models, but its mechanism of action has not yet been established. Val-boroPro is a non-selective inhibitor of post-proline-cleaving serine proteases, and the inhibition of the highly related cytosolic serine proteases Dpp8 and Dpp9 (Dpp8/9) by Val-boroPro was recently demonstrated to trigger an immunostimulatory form of programmed cell death known as pyroptosis selectively in monocytes and macrophages. Here we show that Dpp8/9 inhibition activates the inflammasome sensor protein Nlrp1b, which in turn activates pro-caspase-1 to mediate pyroptosis. This work reveals a previously unrecognized mechanism for activating an innate immune pattern recognition receptor and suggests that Dpp8/9 serve as an intracellular checkpoint to restrain Nlrp1b and the innate immune system.
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Affiliation(s)
- Marian C Okondo
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Sahana D Rao
- Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Cornelius Y Taabazuing
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Ashley J Chui
- Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Sarah E Poplawski
- Department of Developmental, Chemical, & Molecular Biology, Tufts University Sackler School of Graduate Biomedical Sciences, Boston, MA 02111, USA
| | - Darren C Johnson
- Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Daniel A Bachovchin
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
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13
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Taabazuing CY, Okondo MC, Bachovchin DA. Pyroptosis and Apoptosis Pathways Engage in Bidirectional Crosstalk in Monocytes and Macrophages. Cell Chem Biol 2017; 24:507-514.e4. [PMID: 28392147 DOI: 10.1016/j.chembiol.2017.03.009] [Citation(s) in RCA: 374] [Impact Index Per Article: 53.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/16/2017] [Accepted: 03/13/2017] [Indexed: 12/11/2022]
Abstract
Pyroptosis is a lytic form of programmed cell death mediated by the inflammatory caspase-1, -4, and -5. We recently discovered that small-molecule inhibitors of the serine peptidases DPP8 and DPP9 (DPP8/9) induce pro-caspase-1-dependent pyroptosis in monocytes and macrophages. Notably, DPP8/9 inhibitors, unlike microbial agents, absolutely require caspase-1 to induce cell death. Therefore, DPP8/9 inhibitors are useful probes to study caspase-1 in cells. Here, we show that, in the absence of the pyroptosis-mediating substrate gasdermin D (GSDMD), caspase-1 activates caspase-3 and -7 and induces apoptosis, demonstrating that GSDMD is the only caspase-1 substrate that induces pyroptosis. Conversely, we found that, during apoptosis, caspase-3/-7 specifically block pyroptosis by cleaving GSDMD at a distinct site from the inflammatory caspases that inactivates the protein. Overall, this work reveals bidirectional crosstalk between apoptosis and pyroptosis in monocytes and macrophages, further illuminating the complex interplay between cell death pathways in the innate immune system.
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Affiliation(s)
- Cornelius Y Taabazuing
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Marian C Okondo
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Daniel A Bachovchin
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
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14
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Abstract
The Fe(2+)/α-ketoglutarate (αKG)-dependent oxygenases use molecular oxygen to conduct a wide variety of reactions with important biological implications, such as DNA base excision repair, histone demethylation, and the cellular hypoxia response. These enzymes follow a sequential mechanism in which O2 binds and reacts after the primary substrate binds, making those structural factors that promote productive O2 binding central to their chemistry. A large challenge in this field is to identify strategies that engender productive turnover. Factor inhibiting HIF (FIH) is a Fe(2+)/αKG-dependent oxygenase that forms part of the O2 sensing machinery in human cells by hydroxylating the C-terminal transactivation domain (CTAD) found within the HIF-1α protein. The structure of FIH was determined with the O2 analogue NO bound to Fe, offering the first direct insight into the gas binding geometry in this enzyme. Through a combination of density functional theory calculations, {FeNO}(7) electron paramagnetic resonance spectroscopy, and ultraviolet-visible absorption spectroscopy, we demonstrate that CTAD binding stimulates O2 reactivity by altering the orientation of the bound gas molecule. Although unliganded FIH binds NO with moderate affinity, the bound gas can adopt either of two orientations with similar stability; upon CTAD binding, NO adopts a single preferred orientation that is appropriate for supporting oxidative decarboxylation. Combined with other studies of related enzymes, our data suggest that substrate-induced reorientation of bound O2 is the mechanism utilized by the αKG oxygenases to tightly couple O2 activation to substrate hydroxylation.
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Affiliation(s)
- Cornelius Y Taabazuing
- Department of Chemistry, University of Massachusetts , Amherst, Massachusetts 01003, United States
| | - Justin Fermann
- Department of Chemistry, University of Massachusetts , Amherst, Massachusetts 01003, United States
| | - Scott Garman
- Department of Biochemistry and Molecular Biology, University of Massachusetts , Amherst, Massachusetts 01003, United States
| | - Michael J Knapp
- Department of Chemistry, University of Massachusetts , Amherst, Massachusetts 01003, United States
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15
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Pektas S, Taabazuing CY, Knapp MJ. Increased Turnover at Limiting O2 Concentrations by the Thr(387) → Ala Variant of HIF-Prolyl Hydroxylase PHD2. Biochemistry 2015; 54:2851-7. [PMID: 25857330 DOI: 10.1021/bi501540c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PHD2 is a 2-oxoglutarate, non-heme Fe(2+)-dependent oxygenase that senses O2 levels in human cells by hydroxylating two prolyl residues in the oxygen-dependent degradation domain (ODD) of HIF1α. Identifying the active site contacts that determine the rate of reaction at limiting O2 concentrations is crucial for understanding how this enzyme senses pO2 and may suggest methods for chemically altering hypoxia responses. A hydrogen bonding network extends from the Fe(II) cofactor through ordered waters to the Thr(387) residue in the second coordination sphere. Here we tested the impact of the side chain of Thr(387) on the reactivity of PHD2 toward O2 through a combination of point mutagenesis, steady state kinetic experiments and {FeNO}(7) EPR spectroscopy. The steady state kinetic parameters for Thr(387) → Asn were very similar to those of wild-type (WT) PHD2, but kcat and kcat/KM(O2) for Thr(387) → Ala were increased by roughly 15-fold. X-Band electron paramagnetic resonance spectroscopy of the {FeNO}(7) centers of the (Fe+NO+2OG) enzyme forms showed the presence of a more rhombic line shape in Thr(387) → Ala than in WT PHD2, indicating an altered conformation for bound gas in this variant. Here we show that the side chain of residue Thr(387) plays a significant role in determining the rate of turnover by PHD2 at low O2 concentrations.
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Affiliation(s)
- Serap Pektas
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Cornelius Y Taabazuing
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Michael J Knapp
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
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Abstract
The ability to sense and adapt to changes in pO2 is crucial for basic metabolism in most organisms, leading to elaborate pathways for sensing hypoxia (low pO2). This review focuses on the mechanisms utilized by mammals and bacteria to sense hypoxia. While responses to acute hypoxia in mammalian tissues lead to altered vascular tension, the molecular mechanism of signal transduction is not well understood. In contrast, chronic hypoxia evokes cellular responses that lead to transcriptional changes mediated by the hypoxia inducible factor (HIF), which is directly controlled by post-translational hydroxylation of HIF by the non-heme Fe(II)/αKG-dependent enzymes FIH and PHD2. Research on PHD2 and FIH is focused on developing inhibitors and understanding the links between HIF binding and the O2 reaction in these enzymes. Sulfur speciation is a putative mechanism for acute O2-sensing, with special focus on the role of H2S. This sulfur-centered model is discussed, as are some of the directions for further refinement of this model. In contrast to mammals, bacterial O2-sensing relies on protein cofactors that either bind O2 or oxidatively decompose. The sensing modality for bacterial O2-sensors is either via altered DNA binding affinity of the sensory protein, or else due to the actions of a two-component signaling cascade. Emerging data suggests that proteins containing a hemerythrin-domain, such as FBXL5, may serve to connect iron sensing to O2-sensing in both bacteria and humans. As specific molecular machinery becomes identified, these hypoxia sensing pathways present therapeutic targets for diseases including ischemia, cancer, or bacterial infection.
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Affiliation(s)
| | - John A Hangasky
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, United States
| | - Michael J Knapp
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, United States.
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17
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Hangasky JA, Taabazuing CY, Valliere MA, Knapp MJ. Imposing function down a (cupin)-barrel: secondary structure and metal stereochemistry in the αKG-dependent oxygenases. Metallomics 2013; 5:287-301. [PMID: 23446356 PMCID: PMC4109655 DOI: 10.1039/c3mt20153h] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The Fe(ii)/αketoglutarate (αKG) dependent oxygenases catalyze a diverse range of reactions significant in biological processes such as antibiotic biosynthesis, lipid metabolism, oxygen sensing, and DNA and RNA repair. Although functionally diverse, the eight-stranded β-barrel (cupin) and HX(D/E)XnH facial triad motifs are conserved in this super-family of enzymes. Crystal structure analysis of 25 αKG oxygenases reveals two stereoisomers of the Fe cofactor, Anti and Clock, which differ in the relative position of the exchangeable ligand position and the primary substrate. Herein, we discuss the relationship between the chemical mechanism and the secondary coordination sphere of the αKG oxygenases, within the constraints of the stereochemistry of the Fe cofactor. Sequence analysis of the cupin barrel indicates that a small subset of positions constitute the second coordination sphere, which has significant ramifications for the structure of the ferryl intermediate. The competence of both Anti and Clock stereoisomers of Fe points to a ferryl intermediate that is 5 coordinate. The small number of conserved close contacts within the active sites of αKG oxygenases can be extended to chemically related enzymes, such as the αKG-dependent halogenases SyrB2 and CytC3, and the non-αKG dependent dioxygenases isopenicillin N synthase (IPNS) and cysteine dioxygenase (CDO).
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Affiliation(s)
- John A. Hangasky
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
| | | | - Meaghan A. Valliere
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
| | - Michael J. Knapp
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
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18
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Flagg SC, Martin CB, Taabazuing CY, Holmes BE, Knapp MJ. Screening chelating inhibitors of HIF-prolyl hydroxylase domain 2 (PHD2) and factor inhibiting HIF (FIH). J Inorg Biochem 2012; 113:25-30. [PMID: 22687491 DOI: 10.1016/j.jinorgbio.2012.03.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 02/04/2012] [Accepted: 03/09/2012] [Indexed: 12/12/2022]
Abstract
Two primary O(2)-sensors for humans are the HIF-hydroxylases, enzymes that hydroxylate specific residues of the hypoxia inducible factor-α (HIF). These enzymes are factor inhibiting HIF (FIH) and prolyl hydroxylase-2 (PHD2), each an α-ketoglutarate (αKG) dependent, non-heme Fe(II) dioxygenase. Although the two enzymes have similar active sites, FIH hydroxylates Asn(803) of HIF-1α while PHD2 hydroxylates Pro(402) and/or Pro(564) of HIF-1α. The similar structures but unique functions of FIH and PHD2 make them prime targets for selective inhibition leading to regulatory control of diseases such as cancer and stroke. Three classes of iron chelators were tested as inhibitors for FIH and PHD2: pyridines, hydroxypyrones/hydroxypyridinones and catechols. An initial screen of the ten small molecule inhibitors at varied [αKG] revealed a non-overlapping set of inhibitors for PHD2 and FIH. Dose response curves at moderate [αKG] ([αKG]~K(M)) showed that the hydroxypyrones/hydroxypyridinones were selective inhibitors, with IC(50) in the μM range, and that the catechols were generally strong inhibitors of both FIH and PHD2, with IC(50) in the low μM range. As support for binding at the active site of each enzyme as the mode of inhibition, electron paramagnetic resonance (EPR) spectroscopy were used to demonstrate inhibitor binding to the metal center of each enzyme. This work shows some selective inhibition between FIH and PHD2, primarily through the use of simple aromatic or pseudo-aromatic chelators, and suggests that hydroxypyrones and hydroxypyridones may be promising chelates for FIH or PHD2 inhibition.
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Affiliation(s)
- Shannon C Flagg
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
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