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Hahner F, Moll F, Warwick T, Hebchen DM, Buchmann GK, Epah J, Abplanalp W, Schader T, Günther S, Gilsbach R, Brandes RP, Schröder K. Nox4 promotes endothelial differentiation through chromatin remodeling. Redox Biol 2022; 55:102381. [PMID: 35810713 PMCID: PMC9287364 DOI: 10.1016/j.redox.2022.102381] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 06/20/2022] [Indexed: 01/09/2023] Open
Abstract
RATIONALE Nox4 is a constitutively active NADPH oxidase that constantly produces low levels of H2O2. Thereby, Nox4 contributes to cell homeostasis and long-term processes, such as differentiation. The high expression of Nox4 seen in endothelial cells contrasts with the low abundance of Nox4 in stem cells, which are accordingly characterized by low levels of H2O2. We hypothesize that Nox4 is a major contributor to endothelial differentiation, is induced during the process of differentiation, and facilitates homeostasis of the resulting endothelial cells. OBJECTIVE To determine the role of No×4 in differentiation of murine inducible pluripotent stem cells (miPSC) into endothelial cells (ECs). METHODS AND RESULTS miPSC, generated from mouse embryonic wildtype (WT) and Nox4-/- fibroblasts, were differentiated into endothelial cells (miPSC-EC) by stimulation with BMP4 and VEGF. During this process, Nox4 expression increased and knockout of Nox4 prolonged the abundance of pluripotency markers, while expression of endothelial markers was delayed in differentiating Nox4-depleted iPSCs. Eventually, angiogenic capacity of iPSC-ECs is reduced in Nox4 deficient cells, indicating that an absence of Nox4 diminishes stability of the reached phenotype. As an underlying mechanism, we identified JmjD3 as a redox target of Nox4. iPSC-ECs lacking Nox4 display a lower nuclear abundance of the histone demethylase JmjD3, resulting in an increased triple methylation of histone 3 (H3K27me3), which serves as a repressive mark for several genes involved in differentiation. CONCLUSIONS Nox4 promotes differentiation of miPSCs into ECs by oxidation of JmjD3 and subsequent demethylation of H3K27me3, which forced endothelial differentiation and stability.
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Affiliation(s)
- F Hahner
- Institute for Cardiovascular Physiology, Goethe University, Frankfurt, Germany; German Center of Cardiovascular Research (DZHK), Partner Site RheinMain, Frankfurt, Germany
| | - F Moll
- Institute for Cardiovascular Physiology, Goethe University, Frankfurt, Germany; German Center of Cardiovascular Research (DZHK), Partner Site RheinMain, Frankfurt, Germany
| | - T Warwick
- Institute for Cardiovascular Physiology, Goethe University, Frankfurt, Germany; German Center of Cardiovascular Research (DZHK), Partner Site RheinMain, Frankfurt, Germany
| | - D M Hebchen
- Institute for Cardiovascular Physiology, Goethe University, Frankfurt, Germany; German Center of Cardiovascular Research (DZHK), Partner Site RheinMain, Frankfurt, Germany
| | - G K Buchmann
- Institute for Cardiovascular Physiology, Goethe University, Frankfurt, Germany; German Center of Cardiovascular Research (DZHK), Partner Site RheinMain, Frankfurt, Germany
| | - J Epah
- Institute for Cardiovascular Physiology, Goethe University, Frankfurt, Germany; German Center of Cardiovascular Research (DZHK), Partner Site RheinMain, Frankfurt, Germany
| | - W Abplanalp
- Institute for Cardiovascular Regeneration, Goethe University, Frankfurt, Germany; German Center of Cardiovascular Research (DZHK), Partner Site RheinMain, Frankfurt, Germany
| | - T Schader
- Institute for Cardiovascular Physiology, Goethe University, Frankfurt, Germany; German Center of Cardiovascular Research (DZHK), Partner Site RheinMain, Frankfurt, Germany
| | - S Günther
- Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - R Gilsbach
- Institute for Cardiovascular Physiology, Goethe University, Frankfurt, Germany; German Center of Cardiovascular Research (DZHK), Partner Site RheinMain, Frankfurt, Germany
| | - R P Brandes
- Institute for Cardiovascular Physiology, Goethe University, Frankfurt, Germany; German Center of Cardiovascular Research (DZHK), Partner Site RheinMain, Frankfurt, Germany
| | - K Schröder
- Institute for Cardiovascular Physiology, Goethe University, Frankfurt, Germany; German Center of Cardiovascular Research (DZHK), Partner Site RheinMain, Frankfurt, Germany.
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Sobrado P, Tanner JJ. Multiple functionalities of reduced flavin in the non-redox reaction catalyzed by UDP-galactopyranose mutase. Arch Biochem Biophys 2017; 632:59-65. [PMID: 28652025 DOI: 10.1016/j.abb.2017.06.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [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: 06/02/2017] [Revised: 06/21/2017] [Accepted: 06/22/2017] [Indexed: 12/29/2022]
Abstract
Flavin cofactors are widely used by enzymes to catalyze a broad range of chemical reactions. Traditionally, flavins in enzymes are regarded as redox centers, which enable enzymes to catalyze the oxidation or reduction of substrates. However, a new class of flavoenzyme has emerged over the past quarter century in which the flavin functions as a catalytic center in a non-redox reaction. Here we introduce the unifying concept of flavin hot spots to understand and categorize the mechanisms and reactivities of both traditional and noncanonical flavoenzymes. The major hot spots of reactivity include the N5, C4a, and C4O atoms of the isoalloxazine, and the 2' hydroxyl of the ribityl chain. The role of hot spots in traditional flavoenzymes, such as monooxygenases, is briefly reviewed. A more detailed description of flavin hot spots in noncanonical flavoenzymes is provided, with a focus on UDP-galactopyranose mutase, where the N5 functions as a nucleophile that attacks the anomeric carbon atom of the substrate. Recent results from mechanistic enzymology, kinetic crystallography, and computational chemistry provide a complete picture of the chemical mechanism of UDP-galactopyranose mutase.
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Affiliation(s)
- Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA.
| | - John J Tanner
- Departments of Biochemistry and Chemistry, University of Missouri, Columbia, MO 65211, USA.
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Tanner JJ, Boechi L, Andrew McCammon J, Sobrado P. Structure, mechanism, and dynamics of UDP-galactopyranose mutase. Arch Biochem Biophys 2014; 544:128-41. [PMID: 24096172 PMCID: PMC3946560 DOI: 10.1016/j.abb.2013.09.017] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [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: 09/01/2013] [Revised: 09/25/2013] [Accepted: 09/26/2013] [Indexed: 11/16/2022]
Abstract
The flavoenzyme UDP-galactopyranose mutase (UGM) is a key enzyme in galactofuranose biosynthesis. The enzyme catalyzes the 6-to-5 ring contraction of UDP-galactopyranose to UDP-galactofuranose. Galactofuranose is absent in humans yet is an essential component of bacterial and fungal cell walls and a cell surface virulence factor in protozoan parasites. Thus, inhibition of galactofuranose biosynthesis is a valid strategy for developing new antimicrobials. UGM is an excellent target in this effort because the product of the UGM reaction represents the first appearance of galactofuranose in the biosynthetic pathway. The UGM reaction is redox neutral, which is atypical for flavoenzymes, motivating intense examination of the chemical mechanism and structural features that tune the flavin for its unique role in catalysis. These studies show that the flavin functions as nucleophile, forming a flavin-sugar adduct that facilitates galactose-ring opening and contraction. The 3-dimensional fold is novel and conserved among all UGMs, however the larger eukaryotic enzymes have additional secondary structure elements that lead to significant differences in quaternary structure, substrate conformation, and conformational flexibility. Here we present a comprehensive review of UGM three-dimensional structure, provide an update on recent developments in understanding the mechanism of the enzyme, and summarize computational studies of active site flexibility.
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Affiliation(s)
- John J Tanner
- Departments of Chemistry and Biochemistry, University of Missouri, Columbia, MO, United States.
| | - Leonardo Boechi
- Departments of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, United States
| | - J Andrew McCammon
- Departments of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, United States; Howard Hughes Medical Institute, Department of Pharmacology, University of California San Diego, La Jolla, CA, United States
| | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, United States; Virginia Tech Center for Drug Discovery, Virginia Tech, Blacksburg, VA, United States.
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