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Hu Q, Zhu C, Hankins RA, Murmello AR, Marrs GS, Lukesh JC. An ROS-Responsive Donor That Self-Reports Its H 2S Delivery by Forming a Benzoxazole-Based Fluorophore. J Am Chem Soc 2023; 145:25486-25494. [PMID: 37950698 DOI: 10.1021/jacs.3c10446] [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: 11/13/2023]
Abstract
Hydrogen sulfide (H2S), an endogenous signaling molecule, is known to play a pivotal role in neuroprotection, vasodilation, and hormonal regulation. To further explore the biological effects of H2S, refined donors that facilitate its biological delivery, especially under specific (patho) physiological conditions, are needed. In the present study, we demonstrate that ortho-substituted, aryl boronate esters provide two unique and distinct pathways for H2S release from thioamide-based donors: Lewis acid-facilitated hydrolysis and reactive oxygen species (ROS)-induced oxidation/cyclization. Through a detailed structure-activity relationship study, donors that resist hydrolysis and release H2S solely via the latter mechanism were identified, which have the added benefit of providing a potentially useful heterocycle as the lone byproduct of this novel chemistry. To highlight this, we developed an ROS-activated donor (QH642) that simultaneously synthesizes a benzoxazole-based fluorophore en route to its H2S delivery. A distinct advantage of this design over earlier self-reporting donors is that fluorophore formation is possible only if H2S has been discharged from the donor. This key feature eliminates the potential for false positives and provides a more accurate depiction of reaction progress and donor delivery of H2S, including in complex cellular environments.
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Affiliation(s)
- Qiwei Hu
- Department of Chemistry, Wake Forest University, Wake Downtown Campus, Winston-Salem, North Carolina 27101, United States
| | - Changlei Zhu
- Department of Chemistry, Wake Forest University, Wake Downtown Campus, Winston-Salem, North Carolina 27101, United States
| | - Rynne A Hankins
- Department of Chemistry, Wake Forest University, Wake Downtown Campus, Winston-Salem, North Carolina 27101, United States
| | - Allison R Murmello
- Department of Chemistry, Wake Forest University, Wake Downtown Campus, Winston-Salem, North Carolina 27101, United States
| | - Glen S Marrs
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina 27109, United States
| | - John C Lukesh
- Department of Chemistry, Wake Forest University, Wake Downtown Campus, Winston-Salem, North Carolina 27101, United States
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Chikugo A, Irie Y, Tsukano C, Uchino A, Maki T, Kume T, Kawase T, Hirose K, Kageyama Y, Tooyama I, Irie K. Optimization of the Linker Length in the Dimer Model of E22P-Aβ40 Tethered at Position 38. ACS Chem Neurosci 2022; 13:2913-2923. [PMID: 36095282 DOI: 10.1021/acschemneuro.2c00436] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Since amyloid β (Aβ) oligomers are more cytotoxic than fibrils, various dimer models have been synthesized. We focused on the C-terminal region that could form a hydrophobic core in the aggregation process and identified a toxic conformer-restricted dimer model (E22P,G38DAP-Aβ40 dimer) with an l,l-2,6-diaminopimelic acid linker (n = 3) at position 38, which exhibited moderate cytotoxicity. We synthesized four additional linkers (n = 2, 4, 5, 7) to determine the most appropriate distance between the two Aβ40 monomers for a toxic dimer model. Each di-Fmoc-protected two-valent amino acid was synthesized from a corresponding dialdehyde or cycloalkene followed by ozonolysis, using a Horner-Wadsworth-Emmons reaction and asymmetric hydrogenation. Then, the corresponding Aβ40 dimer models with these linkers at position 38 were synthesized using the solid-phase Fmoc strategy. Their cytotoxicity toward SH-SY5Y cells suggested that the shorter the linker length, the stronger the cytotoxicity. Particularly, the E22P,G38DAA-Aβ40 dimer (n = 2) formed protofibrillar aggregates and exhibited the highest cytotoxicity, equivalent to E22P-Aβ42, the most cytotoxic analogue of Aβ42. Ion mobility-mass spectrometry (IM-MS) measurement indicated that all dimer models except the E22P,G38DAA-Aβ40 dimer existed as stable oligomers (12-24-mer). NativePAGE analysis supported the IM-MS data, but larger oligomers (30-150-mer) were also detected after a 24 h incubation. Moreover, E22P,G38DAA-Aβ40, E22P,G38DAP-Aβ40, and E22P,G38DAZ-Aβ40 (n = 5) dimers suppressed long-term potentiation (LTP). Overall, the ability to form fibrils with cross β-sheet structures was key to achieving cytotoxicity, and forming stable oligomers less than 150-mer did not correlate with cytotoxicity and LTP suppression.
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Affiliation(s)
- Ayaka Chikugo
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto606-8502, Japan
| | - Yumi Irie
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto606-8502, Japan
| | - Chihiro Tsukano
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto606-8502, Japan
| | - Ayumi Uchino
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto606-8502, Japan
| | - Takahito Maki
- Department of Applied Pharmacology, Graduate School of Medical and Pharmaceutical Sciences, University of Toyama, Toyama930-0194, Japan
| | - Toshiaki Kume
- Department of Applied Pharmacology, Graduate School of Medical and Pharmaceutical Sciences, University of Toyama, Toyama930-0194, Japan
| | | | | | - Yusuke Kageyama
- Molecular Neuroscience Research Center, Shiga University of Medical Sciences, Shiga520-2192, Japan
| | - Ikuo Tooyama
- Molecular Neuroscience Research Center, Shiga University of Medical Sciences, Shiga520-2192, Japan
| | - Kazuhiro Irie
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto606-8502, Japan
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Zhang S, Yoo S, Snyder DT, Katz BB, Henrickson A, Demeler B, Wysocki VH, Kreutzer AG, Nowick JS. A Disulfide-Stabilized Aβ that Forms Dimers but Does Not Form Fibrils. Biochemistry 2022; 61:252-264. [PMID: 35080857 PMCID: PMC9083094 DOI: 10.1021/acs.biochem.1c00739] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aβ dimers are a basic building block of many larger Aβ oligomers and are among the most neurotoxic and pathologically relevant species in Alzheimer's disease. Homogeneous Aβ dimers are difficult to prepare, characterize, and study because Aβ forms heterogeneous mixtures of oligomers that vary in size and can rapidly aggregate into more stable fibrils. This paper introduces AβC18C33 as a disulfide-stabilized analogue of Aβ42 that forms stable homogeneous dimers in lipid environments but does not aggregate to form insoluble fibrils. The AβC18C33 peptide is readily expressed in Escherichia coli and purified by reverse-phase HPLC to give ca. 8 mg of pure peptide per liter of bacterial culture. SDS-PAGE establishes that AβC18C33 forms homogeneous dimers in the membrane-like environment of SDS and that conformational stabilization of the peptide with a disulfide bond prevents the formation of heterogeneous mixtures of oligomers. Mass spectrometric (MS) studies in the presence of dodecyl maltoside (DDM) further confirm the formation of stable noncovalent dimers. Circular dichroism (CD) spectroscopy establishes that AβC18C33 adopts a β-sheet conformation in detergent solutions and supports a model in which the intramolecular disulfide bond induces β-hairpin folding and dimer formation in lipid environments. Thioflavin T (ThT) fluorescence assays and transmission electron microscopy (TEM) studies indicate that AβC18C33 does not undergo fibril formation in aqueous buffer solutions and demonstrate that the intramolecular disulfide bond prevents fibril formation. The recently published NMR structure of an Aβ42 tetramer (PDB: 6RHY) provides a working model for the AβC18C33 dimer, in which two β-hairpins assemble through hydrogen bonding to form a four-stranded antiparallel β-sheet. It is anticipated that AβC18C33 will serve as a stable, nonfibrilizing, and noncovalent Aβ dimer model for amyloid and Alzheimer's disease research.
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Affiliation(s)
- Sheng Zhang
- Department of Chemistry, University of California Irvine, Irvine, California 92697-2025, United States
| | - Stan Yoo
- Department of Chemistry, University of California Irvine, Irvine, California 92697-2025, United States
| | - Dalton T. Snyder
- Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Benjamin B. Katz
- Department of Chemistry, University of California Irvine, Irvine, California 92697-2025, United States
| | - Amy Henrickson
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Dr., Lethbridge, Alberta, Canada T1K 3M4
| | - Borries Demeler
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Dr., Lethbridge, Alberta, Canada T1K 3M4
| | - Vicki H. Wysocki
- Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Adam G. Kreutzer
- Department of Chemistry, University of California Irvine, Irvine, California 92697-2025, United States,Corresponding Authors: James S. Nowick – Department of Chemistry, University of California, Irvine, California 92697-2025, United States; Department of Pharmaceutical Sciences, University of California, Irvine, California 92697-2025, United States. , Adam G. Kreutzer – Department of Chemistry, University of California, Irvine, California 92697-2025, United States.
| | - James S. Nowick
- Department of Chemistry, University of California Irvine, Irvine, California 92697-2025, United States,Department of Pharmaceutical Sciences, University of California Irvine, Irvine, California 92697-2025, United States,Corresponding Authors: James S. Nowick – Department of Chemistry, University of California, Irvine, California 92697-2025, United States; Department of Pharmaceutical Sciences, University of California, Irvine, California 92697-2025, United States. , Adam G. Kreutzer – Department of Chemistry, University of California, Irvine, California 92697-2025, United States.
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