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Navals P, Rangaswamy AMM, Kasyanchyk P, Berezovski MV, Keillor JW. Conformational Modulation of Tissue Transglutaminase via Active Site Thiol Alkylating Agents: Size Does Not Matter. Biomolecules 2024; 14:496. [PMID: 38672511 PMCID: PMC11048362 DOI: 10.3390/biom14040496] [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: 03/03/2024] [Revised: 04/02/2024] [Accepted: 04/17/2024] [Indexed: 04/28/2024] Open
Abstract
TG2 is a unique member of the transglutaminase family as it undergoes a dramatic conformational change, allowing its mutually exclusive function as either a cross-linking enzyme or a G-protein. The enzyme's dysregulated activity has been implicated in a variety of pathologies (e.g., celiac disease, fibrosis, cancer), leading to the development of a wide range of inhibitors. Our group has primarily focused on the development of peptidomimetic targeted covalent inhibitors, the nature and size of which were thought to be important features to abolish TG2's conformational dynamism and ultimately inhibit both its activities. However, we recently demonstrated that the enzyme was unable to bind guanosine triphosphate (GTP) when catalytically inactivated by small molecule inhibitors. In this study, we designed a library of models targeting covalent inhibitors of progressively smaller sizes (15 to 4 atoms in length). We evaluated their ability to inactivate TG2 by measuring their respective kinetic parameters kinact and KI. Their impact on the enzyme's ability to bind GTP was then evaluated and subsequently correlated to the conformational state of the enzyme, as determined via native PAGE and capillary electrophoresis. All irreversible inhibitors evaluated herein locked TG2 in its open conformation and precluded GTP binding. Therefore, we conclude that steric bulk and structural complexity are not necessary factors to consider when designing TG2 inhibitors to abolish G-protein activity.
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Affiliation(s)
| | | | | | | | - Jeffrey W. Keillor
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (P.N.); (A.M.M.R.); (P.K.); (M.V.B.)
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2
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Wodtke R, Laube M, Hauser S, Meister S, Ludwig FA, Fischer S, Kopka K, Pietzsch J, Löser R. Preclinical evaluation of an 18F-labeled N ε-acryloyllysine piperazide for covalent targeting of transglutaminase 2. EJNMMI Radiopharm Chem 2024; 9:1. [PMID: 38165538 PMCID: PMC10761660 DOI: 10.1186/s41181-023-00231-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 12/15/2023] [Indexed: 01/03/2024] Open
Abstract
BACKGROUND Transglutaminase 2 (TGase 2) is a multifunctional protein and has a prominent role in various (patho)physiological processes. In particular, its transamidase activity, which is rather latent under physiological conditions, gains importance in malignant cells. Thus, there is a great need of theranostic probes for targeting tumor-associated TGase 2, and targeted covalent inhibitors appear to be particularly attractive as vector molecules. Such an inhibitor, equipped with a radionuclide suitable for noninvasive imaging, would be supportive for answering the general question on the possibility for functional characterization of tumor-associated TGase 2. For this purpose, the recently developed 18F-labeled Nε-acryloyllysine piperazide [18F]7b, which is a potent and selective irreversible inhibitor of TGase 2, was subject to a detailed radiopharmacological characterization herein. RESULTS An alternative radiosynthesis of [18F]7b is presented, which demands less than 300 µg of the respective trimethylammonio precursor per synthesis and provides [18F]7b in good radiochemical yields (17 ± 7%) and high (radio)chemical purities (≥ 99%). Ex vivo biodistribution studies in healthy mice at 5 and 60 min p.i. revealed no permanent enrichment of 18F-activity in tissues with the exception of the bone tissue. In vivo pretreatment with ketoconazole and in vitro murine liver microsome studies complemented by mass spectrometric analysis demonstrated that bone uptake originates from metabolically released [18F]fluoride. Further metabolic transformations of [18F]7b include mono-hydroxylation and glucuronidation. Based on blood sampling data and liver microsome experiments, pharmacokinetic parameters such as plasma and intrinsic clearance were derived, which substantiated the apparently rapid distribution of [18F]7b in and elimination from the organisms. A TGase 2-mediated uptake of [18F]7b in different tumor cell lines could not be proven. Moreover, evaluation of [18F]7b in melanoma tumor xenograft models based on A375-hS100A4 (TGase 2 +) and MeWo (TGase 2 -) cells by ex vivo biodistribution and PET imaging studies were not indicative for a specific targeting. CONCLUSION [18F]7b is a valuable radiometric tool to study TGase 2 in vitro under various conditions. However, its suitability for targeting tumor-associated TGase 2 is strongly limited due its unfavorable pharmacokinetic properties as demonstrated in rodents. Consequently, from a radiochemical perspective [18F]7b requires appropriate structural modifications to overcome these limitations.
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Affiliation(s)
- Robert Wodtke
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany.
| | - Markus Laube
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Sandra Hauser
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Sebastian Meister
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Friedrich-Alexander Ludwig
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, 04318, Leipzig, Germany
| | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, 04318, Leipzig, Germany
| | - Klaus Kopka
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, 04318, Leipzig, Germany
- School of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069, Dresden, Germany
| | - Jens Pietzsch
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany
- School of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069, Dresden, Germany
| | - Reik Löser
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany.
- School of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069, Dresden, Germany.
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3
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Gates EWJ, Prince-Hallée A, Heidari Y, Sedighi A, Keillor JW. High-Affinity Fluorogenic Substrate for Tissue Transglutaminase Reveals Enzymatic Hysteresis. Biochemistry 2023; 62:3085-3095. [PMID: 37856791 DOI: 10.1021/acs.biochem.3c00337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
Transglutaminases (TGases) are a family of calcium-dependent enzymes primarily known for their ability to cross-link proteins. Transglutaminase 2 (TG2) is one isozyme in this family whose role is multifaceted. TG2 can act not only as a typical transamidase through its catalytic core but also as a G-protein via its GTP binding site. These two discrete activities are tightly regulated by both environmental stimuli and redox reactions. Ubiquitously expressed in humans, TG2 has been implicated in numerous disease pathologies that require extensive investigation. The catalytic activity of TG2 can be monitored through various mechanisms, including hydrolysis, transamidation, or cleavage of isopeptide bonds. Activity assays are required to monitor the activity of this isozyme not only for studying its transamidation reaction but also for validation of therapeutics designed to abolish this activity. Herein, we present the design, synthesis, and evaluation of a new TG2 activity substrate based on a previously optimized inhibitor scaffold. The substrate APH7 exhibits excellent affinity, selectivity, and reactivity with TG2 (KM = 3.0 μM). Furthermore, its application also allowed the discovery of unique hysteresis at play within the catalytic activity and inhibition reactivity of TG2.
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Affiliation(s)
- Eric W J Gates
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Adrien Prince-Hallée
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Yasaman Heidari
- Dalriada Drug Discovery, Mississauga, Ontario L5N 8G4, Canada
| | | | - Jeffrey W Keillor
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
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4
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Gallo M, Ferrari E, Terrazzan A, Brugnoli F, Spisni A, Taccioli C, Aguiari G, Trentini A, Volinia S, Keillor JW, Bergamini CM, Bianchi N, Pertinhez TA. Metabolic characterisation of transglutaminase 2 inhibitor effects in breast cancer cell lines. FEBS J 2023; 290:5411-5433. [PMID: 37597264 DOI: 10.1111/febs.16931] [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: 12/08/2022] [Revised: 07/04/2023] [Accepted: 08/09/2023] [Indexed: 08/21/2023]
Abstract
Transglutaminase 2 (TG2), which mediates post-translational modifications of multiple intracellular enzymes, is involved in the pathogenesis and progression of cancer. We used 1 H-NMR metabolomics to study the effects of AA9, a novel TG2 inhibitor, on two breast cancer cell lines with distinct phenotypes, MCF-7 and MDA-MB-231. AA9 can promote apoptosis in both cell lines, but it is particularly effective in MD-MB-231, inhibiting transamidation reactions and decreasing cell migration and invasiveness. This metabolomics study provides evidence of a major effect of AA9 on MDA-MB-231 cells, impacting glutamate and aspartate metabolism, rather than on MCF-7 cells, characterised by choline and O-phosphocholine decrease. Interestingly, AA9 treatment induces myo-inositol alteration in both cell lines, indicating action on phosphatidylinositol metabolism, likely modulated by the G protein activity of TG2 on phospholipase C. Considering the metabolic deregulations that characterise various breast cancer subtypes, the existence of a metabolic pathway affected by AA9 further points to TG2 as a promising hot spot. The metabolomics approach provides a powerful tool to monitor the effectiveness of inhibitors and better understand the role of TG2 in cancer.
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Affiliation(s)
- Mariana Gallo
- Department of Medicine and Surgery, University of Parma, Italy
| | - Elena Ferrari
- Department of Medicine and Surgery, University of Parma, Italy
| | - Anna Terrazzan
- Department of Translational Medicine, University of Ferrara, Italy
| | | | - Alberto Spisni
- Department of Medicine and Surgery, University of Parma, Italy
| | - Cristian Taccioli
- Department of Animal Medicine, Production and Health (MAPS), University of Padua, Italy
| | - Gianluca Aguiari
- Department of Neuroscience and Rehabilitation, University of Ferrara, Italy
| | - Alessandro Trentini
- Department of Environmental Sciences and Prevention, University of Ferrara, Italy
| | - Stefano Volinia
- Department of Translational Medicine, University of Ferrara, Italy
| | - Jeffrey W Keillor
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Canada
| | - Carlo M Bergamini
- Department of Neuroscience and Rehabilitation, University of Ferrara, Italy
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5
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Gates EWJ, Calvert ND, Cundy NJ, Brugnoli F, Navals P, Kirby A, Bianchi N, Adhikary G, Shuhendler AJ, Eckert RL, Keillor JW. Cell-Impermeable Inhibitors Confirm That Intracellular Human Transglutaminase 2 Is Responsible for the Transglutaminase-Associated Cancer Phenotype. Int J Mol Sci 2023; 24:12546. [PMID: 37628729 PMCID: PMC10454375 DOI: 10.3390/ijms241612546] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/24/2023] [Accepted: 07/31/2023] [Indexed: 08/27/2023] Open
Abstract
Transglutaminase 2 (TG2) is a multifunctional enzyme primarily responsible for crosslinking proteins. Ubiquitously expressed in humans, TG2 can act either as a transamidase by crosslinking two substrates through formation of an Nε(ɣ-glutaminyl)lysine bond or as an intracellular G-protein. These discrete roles are tightly regulated by both allosteric and environmental stimuli and are associated with dramatic changes in the conformation of the enzyme. The pleiotropic nature of TG2 and multi-faceted activities have resulted in TG2 being implicated in numerous disease pathologies including celiac disease, fibrosis, and cancer. Targeted TG2 therapies have not been selective for subcellular localization, such that currently no tools exist to selectively target extracellular over intracellular TG2. Herein, we have designed novel TG2-selective inhibitors that are not only highly potent and irreversible, but also cell impermeable, targeting only extracellular TG2. We have also further derivatized the scaffold to develop probes that are intrinsically fluorescent or bear an alkyne handle, which target both intra- and extracellular TG2, in order to facilitate cellular labelling and pull-down assays. The fluorescent probes were internalized and imaged in cellulo, and provide the first implicit experimental evidence that by comparison with their cell-impermeable analogues, it is specifically intracellular TG2, and presumably its G-protein activity, that contributes to transglutaminase-associated cancer progression.
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Affiliation(s)
- Eric W. J. Gates
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.W.J.G.); (N.D.C.); (N.J.C.); (P.N.); (A.K.); (A.J.S.)
| | - Nicholas D. Calvert
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.W.J.G.); (N.D.C.); (N.J.C.); (P.N.); (A.K.); (A.J.S.)
| | - Nicholas J. Cundy
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.W.J.G.); (N.D.C.); (N.J.C.); (P.N.); (A.K.); (A.J.S.)
| | - Federica Brugnoli
- Department of Translational Medicine, University of Ferrara, 44021 Ferrara, Italy; (F.B.); (N.B.)
| | - Pauline Navals
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.W.J.G.); (N.D.C.); (N.J.C.); (P.N.); (A.K.); (A.J.S.)
| | - Alexia Kirby
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.W.J.G.); (N.D.C.); (N.J.C.); (P.N.); (A.K.); (A.J.S.)
| | - Nicoletta Bianchi
- Department of Translational Medicine, University of Ferrara, 44021 Ferrara, Italy; (F.B.); (N.B.)
| | - Gautam Adhikary
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (G.A.); (R.L.E.)
| | - Adam J. Shuhendler
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.W.J.G.); (N.D.C.); (N.J.C.); (P.N.); (A.K.); (A.J.S.)
| | - Richard L. Eckert
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (G.A.); (R.L.E.)
| | - Jeffrey W. Keillor
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.W.J.G.); (N.D.C.); (N.J.C.); (P.N.); (A.K.); (A.J.S.)
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6
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Cundy NJ, Arciszewski J, Gates EWJ, Acton SL, Passley KD, Awoonor-Williams E, Boyd EK, Xu N, Pierson É, Fernandez-Ansieta C, Albert MR, McNeil NMR, Adhikary G, Eckert RL, Keillor JW. Novel irreversible peptidic inhibitors of transglutaminase 2. RSC Med Chem 2023; 14:378-385. [PMID: 36846375 PMCID: PMC9945859 DOI: 10.1039/d2md00417h] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 12/22/2022] [Indexed: 12/29/2022] Open
Abstract
Transglutaminase 2 (TG2), also referred to as tissue transglutaminase, plays crucial roles in both protein crosslinking and cell signalling. It is capable of both catalysing transamidation and acting as a G-protein, these activities being conformation-dependent, mutually exclusive, and tightly regulated. The dysregulation of both activities has been implicated in numerous pathologies. TG2 is expressed ubiquitously in humans and is localized both intracellularly and extracellularly. Targeted TG2 therapies have been developed but have faced numerous hurdles including decreased efficacy in vivo. Our latest efforts in inhibitor optimization involve the modification of a previous lead compound's scaffold by insertion of various amino acid residues into the peptidomimetic backbone, and derivatization of the N-terminus with substituted phenylacetic acids, resulting in 28 novel irreversible inhibitors. These inhibitors were evaluated for their ability to inhibit TG2 in vitro and their pharmacokinetic properties, and the most promising candidate 35 (k inact/K I = 760 × 103 M-1 min-1) was tested in a cancer stem cell model. Although these inhibitors display exceptional potency versus TG2, with k inact/K I ratios nearly ten-fold higher than their parent compound, their pharmacokinetic properties and cellular activity limit their therapeutic potential. However, they do serve as a scaffold for the development of potent research tools.
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Affiliation(s)
- Nicholas J Cundy
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
| | - Jane Arciszewski
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
| | - Eric W J Gates
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
| | - Sydney L Acton
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
| | - Kyle D Passley
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
| | - Ernest Awoonor-Williams
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
| | - Elizabeth K Boyd
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
| | - Nancy Xu
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
| | - Élise Pierson
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
| | | | - Marie R Albert
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
| | - Nicole M R McNeil
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
| | - Gautam Adhikary
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine Baltimore Maryland 21201 USA
| | - Richard L Eckert
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine Baltimore Maryland 21201 USA
| | - Jeffrey W Keillor
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
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7
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Mader L, Watt SKI, Iyer HR, Nguyen L, Kaur H, Keillor JW. The war on hTG2: warhead optimization in small molecule human tissue transglutaminase inhibitors. RSC Med Chem 2023; 14:277-298. [PMID: 36846370 PMCID: PMC9945866 DOI: 10.1039/d2md00378c] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 11/15/2022] [Indexed: 11/27/2022] Open
Abstract
Human tissue transglutaminase (hTG2) is a multifunctional enzyme with protein cross-linking and G-protein activity, both of which have been implicated in the progression of diseases such as fibrosis and cancer stem cell propagation when dysregulated, prompting the development of small molecule targeted covalent inhibitors (TCIs) possessing a crucial electrophilic 'warhead'. In recent years there have been significant advances in the library of warheads available for the design of TCIs; however, the exploration of warhead functionality in hTG2 inhibitors has remained relatively stagnant. Herein, we describe a structure-activity relationship study entailing rational design and synthesis for systematic variation of the warhead on a previously reported small molecule inhibitor scaffold, and rigorous kinetic evaluation of inhibitory efficiency, selectivity, and pharmacokinetic stability. This study reveals a strong influence on the kinetic parameters k inact and K I with even subtle variation in warhead structure, suggesting that the warhead plays a significant role in not only reactivity, but also binding affinity, which consequently extends to isozyme selectivity. Warhead structure also influences in vivo stability, which we model by measuring intrinsic reactivity with glutathione, as well as stability in hepatocytes and in whole blood, giving insight into degradation pathways and relative therapeutic potential of different functional groups. This work provides fundamental structural and reactivity information highlighting the importance of strategic warhead design for the development of potent hTG2 inhibitors.
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Affiliation(s)
- Lavleen Mader
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
| | - Sarah K I Watt
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
| | - Harish R Iyer
- Dalriada Drug Discovery Mississauga Ontario L5N 8G4 Canada
| | - Linh Nguyen
- Dalriada Drug Discovery Mississauga Ontario L5N 8G4 Canada
| | - Harpreet Kaur
- Dalriada Drug Discovery Mississauga Ontario L5N 8G4 Canada
| | - Jeffrey W Keillor
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa Ontario K1N 6N5 Canada
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Peptidic Inhibitors and a Fluorescent Probe for the Selective Inhibition and Labelling of Factor XIIIa Transglutaminase. Molecules 2023; 28:molecules28041634. [PMID: 36838622 PMCID: PMC9960274 DOI: 10.3390/molecules28041634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/31/2023] [Accepted: 02/03/2023] [Indexed: 02/11/2023] Open
Abstract
Factor XIIIa (FXIIIa) is a transglutaminase of major therapeutic interest for the development of anticoagulants due to its essential role in the blood coagulation cascade. While numerous FXIIIa inhibitors have been reported, they failed to reach clinical evaluation due to their lack of metabolic stability and low selectivity over transglutaminase 2 (TG2). Furthermore, the chemical tools available for the study of FXIIIa activity and localization are extremely limited. To combat these shortcomings, we designed, synthesised, and evaluated a library of 21 novel FXIIIa inhibitors. Electrophilic warheads, linker lengths, and hydrophobic units were varied on small molecule and peptidic scaffolds to optimize isozyme selectivity and potency. A previously reported FXIIIa inhibitor was then adapted for the design of a probe bearing a rhodamine B moiety, producing the innovative KM93 as the first known fluorescent probe designed to selectively label active FXIIIa with high efficiency (kinact/KI = 127,300 M-1 min-1) and 6.5-fold selectivity over TG2. The probe KM93 facilitated fluorescent microscopy studies within bone marrow macrophages, labelling FXIIIa with high efficiency and selectivity in cell culture. The structure-activity trends with these novel inhibitors and probes will help in the future study of the activity, inhibition, and localization of FXIIIa.
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