1,N6‐Ethenoadenosine, a Damaged Ribonucleotide in DNA: Impact on Translesion Synthesis and Repair

The FASEB Journal

Published On 2021/5

Ribonucleotides in DNA are poorly understood as instigators of DNA damage. In DNA, they can promote genomic instability by causing mutations and are also linked to several diseases. We investigated the impact of ribonucleotide rATP and its damaged analog 1,N6‐ethenoadenosine (1,N6‐εrA) on hpol η‐mediated translesion synthesis (TLS) and RNase H2‐mediated repair. Mass spectral analysis showed that 1,N6‐εrA in DNA generates extensive frameshifts during TLS, which can lead to genomic instability. In addition to this, insertion of deoxypurines (dATP and dGTP) was dominantly seen opposite 1,N6‐εrA in steady‐state kinetic analysis for the TLS process. The repair studies revealed that RNase H2 recognizes but exhibits partial incision activity across from 1,N6‐εrA in DNA, which can lead to the persistence of this adduct into DNA. Our findings identify the mutagenic potential of an unrepaired damaged …

Journal

The FASEB Journal

Published On

2021/5

Volume

35

Authors

Fred Guengerich

Fred Guengerich

Vanderbilt University

Position

Professor of Biochemistry

H-Index(all)

175

H-Index(since 2020)

51

I-10 Index(all)

0

I-10 Index(since 2020)

0

Citation(all)

0

Citation(since 2020)

0

Cited By

0

Research Interests

Enzymology

drug metabolism

cytochrome P450

mutagenesis

University Profile Page

Pratibha P. Ghodke

Pratibha P. Ghodke

Vanderbilt University

Position

Post doctoral fellow at School of Medicine

H-Index(all)

8

H-Index(since 2020)

8

I-10 Index(all)

0

I-10 Index(since 2020)

0

Citation(all)

0

Citation(since 2020)

0

Cited By

0

Research Interests

DNA damage and repair

Translesion synthesis

DNA protein and peptide crosslinks

nucleic acids modification

University Profile Page

Other Articles from authors

Fred Guengerich

Fred Guengerich

Vanderbilt University

Journal of Medicinal Chemistry

Identification of Potent and Selective Inhibitors of Acanthamoeba: Structural Insights into Sterol 14α-Demethylase as a Key Drug Target

Fat mass obesity-associated protein (FTO) is a DNA/RNA demethylase involved in the epigenetic regulation of various genes and is considered a therapeutic target for obesity, cancer, and neurological disorders. Here, we aimed to design novel FTO-selective inhibitors by merging fragments of previously reported FTO inhibitors. Among the synthesized analogues, compound 11b, which merges key fragments of Hz (3) and MA (4), inhibited FTO selectively over alkylation repair homologue 5 (ALKBH5), another DNA/RNA demethylase. Treatment of acute monocytic leukemia NOMO-1 cells with a prodrug of 11b decreased the viability of acute monocytic leukemia cells, increased the level of the FTO substrate N6-methyladenosine in mRNA, and induced upregulation of MYC and downregulation of RARA, which are FTO target genes. Thus, Hz (3)/MA (4) hybrid analogues represent an entry into a new class of FTO …

Fred Guengerich

Fred Guengerich

Vanderbilt University

Chemical Research in Toxicology

In Vivo and In Vitro Induction of Cytochrome P450 3A4 by Thalidomide in Humanized-Liver Mice and Experimental Human Hepatocyte HepaSH cells

Autoinduction of cytochrome P450 (P450) 3A4-mediated metabolism of thalidomide was investigated in humanized-liver mice and human hepatocyte-derived HepaSH cells. The mean plasma ratios of 5-hydroxythalidomide and glutathione adducts to thalidomide were significantly induced (3.5- and 6.0-fold, respectively) by thalidomide treatment daily at 1000 mg/kg for 3 days and measured at 2 h after the fourth administration (on day 4). 5-Hydroxythalidomide was metabolically activated by P450 3A4 in HepaSH cells pretreated with 300 and 1000 μM thalidomide, and 5,6-dihydroxythalidomide was detected. Significant induction of P450 3A4 mRNA expression (4.1-fold) in the livers of thalidomide-treated mice occurred. Thalidomide exerts a variety of actions through multiple mechanisms following bioactivation by induced human P450 3A enzymes.

Fred Guengerich

Fred Guengerich

Vanderbilt University

Formation of potentially toxic metabolites of drugs in reactions catalyzed by human drug-metabolizing enzymes

Data are presented on the formation of potentially toxic metabolites of drugs that are substrates of human drug metabolizing enzymes. The tabular data lists the formation of potentially toxic/reactive products. The data were obtained from in vitro experiments and showed that the oxidative reactions predominate (with 96% of the total potential toxication reactions). Reductive reactions (e.g., reduction of nitro to amino group and reductive dehalogenation) participate to the extent of 4%. Of the enzymes, cytochrome P450 (P450, CYP) enzymes catalyzed 72% of the reactions, myeloperoxidase (MPO) 7%, flavin-containing monooxygenase (FMO) 3%, aldehyde oxidase (AOX) 4%, sulfotransferase (SULT) 5%, and a group of minor participating enzymes to the extent of 9%. Within the P450 Superfamily, P450 Subfamily 3A (P450 3A4 and 3A5) participates to the extent of 27% and the Subfamily 2C (P450 2C9 and P450 2C19 …

Fred Guengerich

Fred Guengerich

Vanderbilt University

Journal of Biological Chemistry

Proteomics, modeling, and fluorescence assays delineate cytochrome b5 residues involved in binding and stimulation of cytochrome P450 17A1 17, 20-lyase

Cytochrome b5 (b5) is known to stimulate some catalytic activities of cytochrome P450 (P450, CYP) enzymes, although mechanisms still need to be defined. The reactions most strongly enhanced by b5 are the 17,20-lyase reactions of P450 17A1 involved in steroid biosynthesis. We had previously used a fluorescently labeled human b5 variant (Alexa 488-T70C-b5) to characterize human P450 17A1-b5 interactions, but subsequent proteomic analyses indicated that lysines in b5 were also modified with Alexa 488 maleimide in addition to Cys-70, due to disulfide dimerization of the T70C mutant. A series of b5 variants were constructed with Cys replacements for the identified lysine residues and labeled with the dye. Fluorescence attenuation and the function of b5 in the steroid lyase reaction depended on the modified position. Apo-b5 (devoid of heme group) studies revealed the lack of involvement of the b5 heme in …

Fred Guengerich

Fred Guengerich

Vanderbilt University

Angewandte Chemie

Oxygen‐18 Labeling Reveals a Mixed Fe− O Mechanism in the Last Step of Cytochrome P450 51 Sterol 14α‐Demethylation

The 14α‐demethylation step is critical in eukaryotic sterol biosynthesis, catalyzed by cytochrome P450 (P450) Family 51 enzymes, for example, with lanosterol in mammals. This conserved three‐step reaction terminates in a C−C cleavage step that generates formic acid, the nature of which has been controversial. Proposed mechanisms involve roles of P450 Compound 0 (ferric peroxide anion, FeO2−) or Compound I (perferryl oxygen, FeO3+) reacting with either the aldehyde or its hydrate, respectively. Analysis of 18O incorporation into formic acid from 18O2 provides a means of distinguishing the two mechanisms. Human P450 51A1 incorporated 88 % 18O (one atom) into formic acid, consistent with a major but not exclusive FeO2− mechanism. Two P450 51 orthologs from amoeba and yeast showed similar results, while two orthologs from pathogenic trypanosomes showed roughly equal contributions of both …

Fred Guengerich

Fred Guengerich

Vanderbilt University

Journal of Biological Chemistry

Ninety-eight semesters of cytochrome P450 enzymes and related topics—What have I taught and learned?

This Reflection article begins with my family background and traces my career through elementary and high school, followed by time at the University of Illinois, Vanderbilt University, the University of Michigan, and then for 98 semesters as a Vanderbilt University faculty member. My research career has dealt with aspects of cytochrome P450 enzymes, and the basic biochemistry has had applications in fields as diverse as drug metabolism, toxicology, medicinal chemistry, pharmacogenetics, biological engineering, and bioremediation. I am grateful for the opportunity to work with the Journal of Biological Chemistry not only as an author but also for 34 years as an Editorial Board Member, Associate Editor, Deputy Editor, and interim Editor-in-Chief. Thanks are extended to my family and my mentors, particularly Profs. Harry Broquist and Minor J. Coon, and the more than 170 people who have trained with me. I have …

Fred Guengerich

Fred Guengerich

Vanderbilt University

ACS catalysis

Oxygen-18 Labeling Defines a Ferric Peroxide (Compound 0) Mechanism in the Oxidative Deformylation of Aldehydes by Cytochrome P450 2B4

Most cytochrome P450 (P450) oxidations are considered to occur with the active oxidant being a perferryl oxygen (FeO3+, Compound I). However, a ferric peroxide (FeO2̅, Compound 0) mechanism has been proposed, as well, particularly for aldehyde substrates. We investigated three of these systems, the oxidative deformylation of the model substrates citronellal, 2-phenylpropionaldehyde, and 2-methyl-2-phenylpropionaldehyde by rabbit P450 2B4, using 18O labeling. The formic acid product contained one 18O derived from 18O2, which is indicative of a dominant Compound 0 mechanism. The formic acid also contained only one 18O derived from H218O, which ruled out a Compound I mechanism. The possibility of a Baeyer–Villiger reaction was examined by using synthesized possible intermediates, but our data do not support its presence. Overall, these findings unambiguously demonstrate the role of the …

Fred Guengerich

Fred Guengerich

Vanderbilt University

Principles of Xenobiotic Metabolism (Biotransformation)

This chapter provides a general overview of metabolic reactions and their significance. Basic concepts and terminology related to biotransformation, activity, and toxicityToxicity are explained and discussed. Major enzymes involved in oxidationOxidation, reductionReduction, hydrolytic, and conjugationConjugation are covered including enzyme nomenclature, localization, catalytic cycle, coenzymes, relevance of individual enzymes, types of reactions, substrates and metabolites, influence of metabolic reactions on the activity/toxicity of xenobiotics, enzyme inhibition, and relevance if applicable.

Fred Guengerich

Fred Guengerich

Vanderbilt University

Journal of Biological Chemistry

The multistep oxidation of cholesterol to pregnenolone by human cytochrome P450 11A1 is highly processive

Cytochrome P450 (P450, CYP) 11A1 is the classical cholesterol side chain cleavage enzyme (P450scc) that removes six carbons of the side chain, the first and rate-limiting step in the synthesis of all mammalian steroids. The reaction is a 3-step, 6-electron oxidation that proceeds via formation of 22R-hydroxy (OH) and 20R,22R-(OH)2 cholesterol, yielding pregnenolone. We expressed human P450 11A1 in bacteria, purified the enzyme in the absence of nonionic detergents, and assayed pregnenolone formation by HPLC-mass spectrometry of the dansyl hydrazone. The reaction was inhibited by the nonionic detergent Tween 20, and several lipids did not enhance enzymatic activity. The 22R-OH and 20R,22R-(OH)2 cholesterol intermediates were bound to P450 11A1 relatively tightly, as judged by steady-state optical titrations and koff rates. The electron donor adrenodoxin had little effect on binding; the substrate …

2023/11/24

Article Details
Fred Guengerich

Fred Guengerich

Vanderbilt University

Journal of Biological Chemistry

Processive kinetics in the three-step lanosterol 14α-demethylation reaction catalyzed by human cytochrome P450 51A1

Cytochrome P450 (P450, CYP) family 51 enzymes catalyze the 14α-demethylation of sterols, leading to critical products used for membranes and the production of steroids, as well as signaling molecules. In mammals, P450 51 catalyzes the 3-step, 6-electron oxidation of lanosterol to form (4β,5α)-4,4-dimethyl-cholestra-8,14,24-trien-3-ol (FF-MAS). P450 51A1 can also use 24,25-dihydrolanosterol (a natural substrate in the Kandutsch-Russell cholesterol pathway). 24,25-Dihydrolanosterol and the corresponding P450 51A1 reaction intermediates, the 14α-alcohol and -aldehyde derivatives of dihydrolanosterol, were synthesized to study the kinetic processivity of the overall 14α-demethylation reaction of human P450 51A1. A combination of steady-state kinetic parameters, steady-state binding constants, dissociation rates of P450-sterol complexes, and kinetic modeling of the time course of oxidation of a P450 …

Fred Guengerich

Fred Guengerich

Vanderbilt University

Nucleic Acids Research

Basis for the discrimination of supercoil handedness during DNA cleavage by human and bacterial type II topoisomerases

To perform double-stranded DNA passage, type II topoisomerases generate a covalent enzyme-cleaved DNA complex (i.e. cleavage complex). Although this complex is a requisite enzyme intermediate, it is also intrinsically dangerous to genomic stability. Consequently, cleavage complexes are the targets for several clinically relevant anticancer and antibacterial drugs. Human topoisomerase IIα and IIβ and bacterial gyrase maintain higher levels of cleavage complexes with negatively supercoiled over positively supercoiled DNA substrates. Conversely, bacterial topoisomerase IV is less able to distinguish DNA supercoil handedness. Despite the importance of supercoil geometry to the activities of type II topoisomerases, the basis for supercoil handedness recognition during DNA cleavage has not been characterized. Based on the results of benchtop and rapid-quench flow kinetics experiments, the forward …

Fred Guengerich

Fred Guengerich

Vanderbilt University

Xenobiotica

The influence of temperature on the metabolic activity of CYP2C9, CYP2C19, and CYP3A4 genetic variants in vitro

1. Temperature is considered to affect the activity of drug-metabolizing enzymes; however, no previous studies have compared temperature dependency among cytochrome P450 genetic variants. This study aimed to analyse warfarin 7-hydroxylation by CYP2C9 variants; omeprazole 5-hydroxylation by CYP2C19 variants; and midazolam 1-hydroxylation by CYP3A4 variants at 34 °C, 37 °C, and 40 °C.2. Compared with that seen at 37 °C, the intrinsic clearance rates (Vmax/Km) of CYP2C9.1 and .2 were decreased (76 ∼ 82%), while that of CYP2C9.3 was unchanged at 34 °C. At 40 °C, CYP2C9.1, .2, and .3 exhibited increased (121%), unchanged and decreased (87%) intrinsic clearance rates, respectively. At 34 °C, the clearance rates of CYP2C19.1A and .10 were decreased (71 ∼ 86%), that of CYP2C19.1B was unchanged, and those of CYP2C19.8 and .23 were increased (130 ∼ 134%). At 40 …

Fred Guengerich

Fred Guengerich

Vanderbilt University

Food and Chemical Toxicology

FEMA GRAS assessment of natural flavor complexes: Lemongrass oil, chamomile oils, citronella oil and related flavoring ingredients

In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a program for the re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavor ingredients. This publication, eleventh in the series, evaluates the safety of NFCs characterized by primary alcohol, aldehyde, carboxylic acid, ester and lactone constituents derived from terpenoid biosynthetic pathways and/or lipid metabolism. The scientific-based evaluation procedure published in 2005 and updated in 2018 that relies on a complete constituent characterization of the NFC and organization of the constituents into congeneric groups. The safety of the NFCs is evaluated using the threshold of toxicological concern (TTC) concept in addition to data on estimated intake, metabolism and toxicology of members of the congeneric groups and for the NFC under evaluation. The scope of the safety evaluation …

Fred Guengerich

Fred Guengerich

Vanderbilt University

Food and Chemical Toxicology

FEMA GRAS assessment of derivatives of basil, nutmeg, parsley, tarragon and related allylalkoxybenzene-containing natural flavor complexes

In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a program for the re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavoring ingredients in food. In this publication, tenth in the series, NFCs containing a high percentage of at least one naturally occurring allylalkoxybenzene constituent with a suspected concern for genotoxicity and/or carcinogenicity are evaluated. In a related paper, ninth in the series, NFCs containing anethole and/or eugenol and relatively low percentages of these allylalkoxybenzenes are evaluated. The Panel applies the threshold of toxicological concern (TTC) concept and evaluates relevant toxicology data on the NFCs and their respective constituent congeneric groups. For NFCs containing allylalkoxybenzene constituent(s), the estimated intake of the constituent is compared to the TTC for compounds with structural …

Fred Guengerich

Fred Guengerich

Vanderbilt University

International Journal of Molecular Sciences

Identification of Three Human POLH Germline Variants Defective in Complementing the UV-and Cisplatin-Sensitivity of POLH-Deficient Cells

DNA polymerase (pol) η is responsible for error-free translesion DNA synthesis (TLS) opposite ultraviolet light (UV)-induced cis-syn cyclobutane thymine dimers (CTDs) and cisplatin-induced intrastrand guanine crosslinks. POLH deficiency causes one form of the skin cancer-prone disease xeroderma pigmentosum variant (XPV) and cisplatin sensitivity, but the functional impacts of its germline variants remain unclear. We evaluated the functional properties of eight human POLH germline in silico-predicted deleterious missense variants, using biochemical and cell-based assays. In enzymatic assays, utilizing recombinant pol η (residues 1—432) proteins, the C34W, I147N, and R167Q variants showed 4- to 14-fold and 3- to 5-fold decreases in specificity constants (kcat/Km) for dATP insertion opposite the 3’-T and 5′-T of a CTD, respectively, compared to the wild-type, while the other variants displayed 2- to 4-fold increases. A CRISPR/Cas9-mediated POLH knockout increased the sensitivity of human embryonic kidney 293 cells to UV and cisplatin, which was fully reversed by ectopic expression of wild-type pol η, but not by that of an inactive (D115A/E116A) or either of two XPV-pathogenic (R93P and G263V) mutants. Ectopic expression of the C34W, I147N, and R167Q variants, unlike the other variants, did not rescue the UV- and cisplatin-sensitivity in POLH-knockout cells. Our results indicate that the C34W, I147N, and R167Q variants—substantially reduced in TLS activity—failed to rescue the UV- and cisplatin-sensitive phenotype of POLH-deficient cells, which also raises the possibility that such hypoactive germline POLH variants may …

Fred Guengerich

Fred Guengerich

Vanderbilt University

Journal of inorganic biochemistry

Hydroxylation and lyase reactions of steroids catalyzed by mouse cytochrome P450 17A1 (Cyp17a1)

Cytochrome P450 17A1 (CYP17A1) catalyzes 17α-hydroxylation and 17,20-lyase reactions with steroid hormones. Mice contain an orthologous Cyp17a1 enzyme in the genome, and its amino acid sequence has high similarity with human CYP17A1. We purified recombinant mouse Cyp17a1 and characterized its oxidation reactions with progesterone and pregnenolone. The open reading frame of the mouse Cyp17a1 gene was inserted and successfully expressed in Escherichia coli and then purified using Ni2+-nitrilotriacetic acid (NTA) affinity column chromatography. Purified mouse Cyp17a1 displayed typical Type I binding titration spectral changes upon the addition of progesterone, 17α-OH progesterone, pregnenolone, and 17α-OH pregnenolone, with similar binding affinities to those of human CYP17A1. Catalytic activities for 17α-hydroxylation and 17,20-lyase reactions were studied using ultra-performance …

Fred Guengerich

Fred Guengerich

Vanderbilt University

The Importance of Biotransformation

Biotransformation is important in considerations of toxicity of chemicals. What begins as a well-defined compound may lead to a mixture of chemicals after it enters the body. The changes may be beneficial or detrimental. A potentially harmful chemical may be rapidly inactivated, at low doses. Conversely, an innocuous compound may be transformed into a toxic one. There are cases of both detoxication and bioactivation for the same chemical, sometimes even with the same enzyme being involved in both changes (e.g., aflatoxin B1 and cytochrome P450 3A4). A proper understanding of the chemical changes, the enzymes involved, and the kinetics of changes is needed to understand the outcomes regarding safety assessment.

Fred Guengerich

Fred Guengerich

Vanderbilt University

Drug Metabolism and Disposition

Cytochrome P450 enzymes as drug targets in human disease

Although the mention of cytochrome P450 (P450, CYP) inhibition usually brings to mind unwanted variability in pharmacokinetics, in several cases P450s are good targets for inhibition. These P450s are essential but in certain disease states it is desirable to reduce the concentrations of their products. Most of the attention to date has been with human P450s 5A1, 11A1, 11B1, 11B2, 17A1, 19A1, and 51A1. In some of those cases, there are multiple drugs in us, e.g., exemestane, letrozole, and anastrozole with P450 19A1, the steroid aromatase target in breast cancer. There are also several targets that are less developed, e. g. P450s 2A6, 8B1, 4A11, 24A1, 26A1, and 26B1.Significance Statement The selective inhibition of certain P450s that have major physiological functions has been shown to be very efficacious in certain human diseases. In several cases the search for better drugs continues.

Fred Guengerich

Fred Guengerich

Vanderbilt University

Steroid 17α-hydroxylase/17, 20-lyase (cytochrome P450 17A1)

Cytochrome P450 (P450) 17A1 plays a key role in steroidogenesis, in that this enzyme catalyzes the 17α-hydroxylation of both pregnenolone and progesterone, followed by a lyase reaction to cleave the C-20 land C-21 carbons from each steroid. The reactions are important in the production of both glucocorticoids and androgens. The enzyme is critical in humans but is also a drug target in treatment of prostate cancer. Detailed methods are described for the heterologous expression of human P450 17A1 in bacteria, purification of the recombinant enzyme, reconstitution of the enzyme system in the presence of cytochrome b5, and chromatographic procedures for sensitive analyses of reaction products. Historic assay approaches are reviewed. Some information is also provided about outstanding questions in the research field, including catalytic mechanisms and searches for selective inhibitors.

Fred Guengerich

Fred Guengerich

Vanderbilt University

Direct addition of flavors, including taste and flavor modifiers

The addition of flavorings to food and beverages provides practically unlimited opportunities for innovation, for maintaining and enhancing palatability, and is one essential element of a stable supply of nutritious consumer products. A safety evaluation by the Flavor and Extract Manufacturers Association (FEMA) Expert Panel provides a pathway for flavor producers and users to achieve regulatory authority to use for substances under the conditions of intended use as a flavoring. This chapter describes the factors that contribute to the safety assessment process that is conducted by the Expert Panel, and provides examples of specific flavorings and types of flavorings that are considered. The chapter also describes future issues and opportunities likely to be encountered within the context of the FEMA generally recognized as safe assessment of flavorings.

Other articles from The FASEB Journal journal

Bahram Samanfar, PhD

Bahram Samanfar, PhD

Carleton University

The FASEB Journal

Hydrogen peroxide sensitivity connects the activity of COX5A and NPR3 to the regulation of YAP1 expression

Reactive oxygen species (ROS) are among the most severe types of cellular stressors with the ability to damage essential cellular biomolecules. Excess levels of ROS are correlated with multiple pathophysiological conditions including neurodegeneration, diabetes, atherosclerosis, and cancer. Failure to regulate the severely imbalanced levels of ROS can ultimately lead to cell death, highlighting the importance of investigating the molecular mechanisms involved in the detoxification procedures that counteract the effects of these compounds in living organisms. One of the most abundant forms of ROS is H2O2, mainly produced by the electron transport chain in the mitochondria. Numerous genes have been identified as essential to the process of cellular detoxification. Yeast YAP1, which is homologous to mammalian AP‐1 type transcriptional factors, has a key role in oxidative detoxification by upregulating the …

Zanou Nadège

Zanou Nadège

Université de Lausanne

The FASEB Journal

Repeated sprint training in hypoxia induces specific skeletal muscle adaptations through S100A protein signaling

Athletes increasingly engage in repeated sprint training consisting in repeated short all‐out efforts interspersed by short recoveries. When performed in hypoxia (RSH), it may lead to greater training effects than in normoxia (RSN); however, the underlying molecular mechanisms remain unclear. This study aimed at elucidating the effects of RSH on skeletal muscle metabolic adaptations as compared to RSN. Sixteen healthy young men performed nine repeated sprint training sessions in either normoxia (FIO2 = 0.209, RSN, n = 7) or normobaric hypoxia (FIO2 = 0.136, RSH, n = 9). Before and after the training period, exercise performance was assessed by using repeated sprint ability (RSA) and Wingate tests. Vastus lateralis muscle biopsies were performed to investigate muscle metabolic adaptations using proteomics combined with western blot analysis. Similar improvements were observed in RSA and …

Junken Aoki

Junken Aoki

Tohoku University

The FASEB Journal

Group III secreted phospholipase A2‐driven lysophospholipid pathway protects against allergic asthma

Asthma is a chronic inflammatory disease of the airways characterized by recurrent episodes of airway obstruction, hyperresponsiveness, remodeling, and eosinophilia. Phospholipase A2s (PLA2s), which release fatty acids and lysophospholipids from membrane phospholipids, have been implicated in exacerbating asthma by generating pro‐asthmatic lipid mediators, but an understanding of the association between individual PLA2 subtypes and asthma is still incomplete. Here, we show that group III‐secreted PLA2 (sPLA2‐III) plays an ameliorating, rather than aggravating, role in asthma pathology. In both mouse and human lungs, sPLA2‐III was expressed in bronchial epithelial cells and decreased during the asthmatic response. In an ovalbumin (OVA)‐induced asthma model, Pla2g3−/− mice exhibited enhanced airway hyperresponsiveness, eosinophilia, OVA‐specific IgE production, and type 2 cytokine …

Nihal Terzi Cizmecioglu

Nihal Terzi Cizmecioglu

Orta Dogu Teknik Üniversitesi

The FASEB Journal

SETD3 regulates endoderm differentiation of mouse embryonic stem cells through canonical Wnt signaling pathway

With self‐renewal and pluripotency features, embryonic stem cells (ESCs) provide an invaluable tool to investigate early cell fate decisions. Pluripotency exit and lineage commitment depend on precise regulation of gene expression that requires coordination between transcription (TF) and chromatin factors in response to various signaling pathways. SET domain‐containing 3 (SETD3) is a methyltransferase that can modify histones in the nucleus and actin in the cytoplasm. Through an shRNA screen, we previously identified SETD3 as an important factor in the meso/endodermal lineage commitment of mouse ESCs (mESC). In this study, we identified SETD3‐dependent transcriptomic changes during endoderm differentiation of mESCs using time‐course RNA‐seq analysis. We found that SETD3 is involved in the timely activation of the endoderm‐related gene network. The canonical Wnt signaling pathway was …

Rabab Hamed Sayed

Rabab Hamed Sayed

Cairo University

The FASEB Journal

Ezetimibe ameliorates cisplatin‐induced nephrotoxicity: A novel therapeutic approach via modulating AMPK/Nrf2/TXNIP signaling

Cisplatin (Cis) is among the most powerful antineoplastic medications, nevertheless, its serious side effects; particularly nephrotoxicity designates a major concern. Previous studies reported that ezetimibe (Eze), a well‐known antihyperlipidemic drug, exerts additional trivial pharmacological effects. In this work, we displayed Eze as an intriguing protective candidate in a cisplatin‐induced nephrotoxicity rat model through AMPK activation. Eze (10 mg/kg, p.o.) was administered for two weeks and Cis (10 mg/kg, i.p.) was administered on the 10th day to induce nephrotoxicity in male Wistar rats. Treatment with Eze greatly augmented the phosphorylation of adenosine 5′‐monophosphate‐activated protein kinase (AMPK) and the antioxidant regulator; nuclear factor erythroid 2‐related factor 2 (Nrf2), thus, mitigating oxidative injury through induction of the antioxidant enzymes, such as heme oxygenase‐1 (HO‐1) and …

Harini Krishnan

Harini Krishnan

Stony Brook University

The FASEB Journal

Biochemical characterization of the Drosophila insulin receptor kinase and longevity‐associated mutants

Drosophila melanogaster (fruit fly) insulin receptor (D‐IR) is highly homologous to the human counterpart. Like the human pathway, D‐IR responds to numerous insulin‐like peptides to activate cellular signals that regulate growth, development, and lipid metabolism in fruit flies. Allelic mutations in the D‐IR kinase domain elevate life expectancy in fruit flies. We developed a robust heterologous expression system to express and purify wild‐type and longevity‐associated mutant D‐IR kinase domains to investigate enzyme kinetics and substrate specificities. D‐IR exhibits remarkable similarities to the human insulin receptor kinase domain but diverges in substrate preferences. We show that longevity‐associated mutations reduce D‐IR catalytic activity. Deletion of the unique kinase insert domain portion or mutations proximal to activating tyrosines do not influence kinase activity, suggesting their potential role in …

Aria F. Olumi, M.D.

Aria F. Olumi, M.D.

Harvard University

The FASEB Journal

Role of ecto‐5′‐nucleotidase in bladder function

Purinergic signaling plays an important role in regulating bladder contractility and voiding. Abnormal purinergic signaling is associated with lower urinary tract symptoms (LUTS). Ecto‐5′‐nucleotidase (NT5E) catalyzes dephosphorylation of extracellular AMP to adenosine, which in turn promotes adenosine‐A2b receptor signaling to relax bladder smooth muscle (BSM). The functional importance of this mechanism was investigated using Nt5e knockout (Nt5eKO) mice. Increased voiding frequency of small voids revealed by voiding spot assay was corroborated by urodynamic studies showing shortened voiding intervals and decreased bladder compliance. Myography indicated reduced contractility of Nt5eKO BSM. These data support a role for NT5E in regulating bladder function through modulation of BSM contraction and relaxation. However, the abnormal bladder phenotype of Nt5eKO mice is much milder than …

Ayman M. Ibrahim

Ayman M. Ibrahim

Cairo University

The FASEB Journal

Thioredoxin‐1 and its mimetic peptide improve systolic cardiac function and remodeling after myocardial infarction

Myocardial infarction (MI) is characterized by a significant loss of cardiomyocytes (CMs), and it is suggested that reactive oxygen species (ROS) are involved in cell cycle arrest, leading to impaired CM renewal. Thioredoxin‐1 (Trx‐1) scavenges ROS and may play a role in restoring CM renewal. However, the truncated form of Trx‐1, Trx‐80, can compromise its efficacy by exerting antagonistic effects. Therefore, a Trx‐1 mimetic peptide called CB3 was tested as an alternative way to restore CMs. This study aimed to investigate the effects of Trx‐1, Trx‐80, and CB3 on mice with experimental MI and study the underlying mechanism of CB3 on CMs. Mouse cardiac parameters were quantified by echocardiography, and infarction size and fibrosis determined using Trichrome and Picro‐Sirius Red staining. The study found that Trx‐1 and CB3 improved mouse cardiac function, reduced the size of cardiac infarct and fibrosis …

Xiaoyu Zhang

Xiaoyu Zhang

University of Kansas

The FASEB Journal

TAF7L regulates early stages of male germ cell development in the rat

Male germ cell development is dependent on the orchestrated regulation of gene networks. TATA‐box binding protein associated factors (TAFs) facilitate interactions of TATA‐binding protein with the TATA element, which is known to coordinate gene transcription during organogenesis. TAF7 like (Taf7l) is situated on the X chromosome and has been implicated in testis development. We examined the biology of TAF7L in testis development using the rat. Taf7l was prominently expressed in preleptotene to leptotene spermatocytes. To study the impact of TAF7L on the testis we generated a global loss‐of‐function rat model using CRISPR/Cas9 genome editing. Exon 3 of the Taf7l gene was targeted. A founder was generated possessing a 110 bp deletion within the Taf7l locus, which resulted in a frameshift and the premature appearance of a stop codon. The mutation was effectively transmitted through the germline …

Taiho Kambe

Taiho Kambe

Kyoto University

The FASEB Journal

Zinc and manganese homeostasis closely interact in mammalian cells

Understanding the homeostatic interactions among essential trace metals is important for explaining their roles in cellular systems. Recent studies in vertebrates suggest that cellular Mn metabolism is related to Zn metabolism in multifarious cellular processes. However, the underlying mechanism remains unclear. In this study, we examined the changes in the expression of proteins involved in cellular Zn and/or Mn homeostatic control and measured the Mn as well as Zn contents and Zn enzyme activities to elucidate the effects of Mn and Zn homeostasis on each other. Mn treatment decreased the expression of the Zn homeostatic proteins metallothionein (MT) and ZNT1 and reduced Zn enzyme activities, which were attributed to the decreased Zn content. Moreover, loss of Mn efflux transport protein decreased MT and ZNT1 expression and Zn enzyme activity without changing extracellular Mn content. This …

Ninu Poulose

Ninu Poulose

University of Oxford

The FASEB Journal

CDK9 inhibition activates innate immune response through viral mimicry

Cancer cells frequently exhibit hyperactivation of transcription, which can lead to increased sensitivity to compounds targeting the transcriptional kinases, in particular CDK9. However, mechanistic details of CDK9 inhibition‐induced cancer cell‐selective anti‐proliferative effects remain largely unknown. Here, we discover that CDK9 inhibition activates the innate immune response through viral mimicry in cancer cells. In MYC over‐expressing prostate cancer cells, CDK9 inhibition leads to the gross accumulation of mis‐spliced RNA. Double‐stranded RNA (dsRNA)‐activated kinase can recognize these mis‐spliced RNAs, and we show that the activity of this kinase is required for the CDK9 inhibitor‐induced anti‐proliferative effects. Using time‐resolved transcriptional profiling (SLAM‐seq), targeted proteomics, and ChIP‐seq, we show that, similar to viral infection, CDK9 inhibition significantly suppresses transcription …

Yasmine Aguib

Yasmine Aguib

Imperial College London

The FASEB Journal

Thioredoxin‐1 and its mimetic peptide improve systolic cardiac function and remodeling after myocardial infarction

Myocardial infarction (MI) is characterized by a significant loss of cardiomyocytes (CMs), and it is suggested that reactive oxygen species (ROS) are involved in cell cycle arrest, leading to impaired CM renewal. Thioredoxin‐1 (Trx‐1) scavenges ROS and may play a role in restoring CM renewal. However, the truncated form of Trx‐1, Trx‐80, can compromise its efficacy by exerting antagonistic effects. Therefore, a Trx‐1 mimetic peptide called CB3 was tested as an alternative way to restore CMs. This study aimed to investigate the effects of Trx‐1, Trx‐80, and CB3 on mice with experimental MI and study the underlying mechanism of CB3 on CMs. Mouse cardiac parameters were quantified by echocardiography, and infarction size and fibrosis determined using Trichrome and Picro‐Sirius Red staining. The study found that Trx‐1 and CB3 improved mouse cardiac function, reduced the size of cardiac infarct and fibrosis …

Melanie Haffner-Luntzer

Melanie Haffner-Luntzer

Universität Ulm

The FASEB Journal

Mechanical induction of osteoanabolic Wnt1 promotes osteoblast differentiation via Plat

Physical activity‐induced mechanical stimuli play a crucial role in preserving bone mass and structure by promoting bone formation. While the Wnt pathway is pivotal for mediating the osteoblast response to loading, the exact mechanisms are not fully understood. Here, we found that mechanical stimulation induces osteoblastic Wnt1 expression, resulting in an upregulation of key osteogenic marker genes, including Runx2 and Sp7, while Wnt1 knockdown using siRNA prevented these effects. RNAseq analysis identified Plat as a major target through which Wnt1 exerts its osteogenic influence. This was corroborated by Plat depletion using siRNA, confirming its positive role in osteogenic differentiation. Moreover, we demonstrated that mechanical stimulation enhances Plat expression, which, in turn leads to increased expression of osteogenic markers like Runx2 and Sp7. Notably, Plat depletion by siRNA prevented …

Silvia Liu

Silvia Liu

University of Pittsburgh

The FASEB Journal

Proteome characterization of liver–kidney comorbidity after microbial sepsis

Sepsis is a life‐threatening condition that occurs when the body responds to an infection but subsequently triggers widespread inflammation and impaired blood flow. These pathologic responses can rapidly cause multiple organ dysfunction or failure either one by one or simultaneously. The fundamental common mechanisms involved in sepsis‐induced multiple organ dysfunction remain unclear. Here, employing quantitative global and phosphoproteomics, we examine the liver's temporal proteome and phosphoproteome changes after moderate sepsis induced by cecum ligation and puncture. In total, 4593 global proteins and 1186 phosphoproteins according to 3275 phosphosites were identified. To characterize the liver–kidney comorbidity after sepsis, we developed a mathematical model and performed cross‐analyses of liver and kidney proteome data obtained from the same set of mice. Beyond immune …

Zhu Wenhua

Zhu Wenhua

Xi'an Jiaotong University

The FASEB Journal

IL‐21 promoting angiogenesis contributes to the development of psoriasis

Background Elevated IL‐21 expression which can effectively induce Th17 cell differentiation has been implicated in the pathogenesis of psoriasis, but its role in angiogenesis remains poorly understood. Methods PASI and PSI score assessment was applied to evaluate the severity of psoriatic lesions. The expression of IL‐21, IL‐21 receptor (IL‐21R), CD31, VEGFA, MMP‐9, and ICAM‐1 in skin was determined by immunohistochemistry or quantitative real‐time polymerase chain reaction. The serum level of IL‐21 was measured by enzyme‐linked immunosorbent assay (ELISA). Then, their correlation was analyzed statistically. Human umbilical vein endothelial cells (HUVECs) cocultured with conditional medium from normal human epidermal keratinocytes (NHEKs) were treated with IL‐21 and/or M5 cocktail (mixture of IL‐1α, IL‐17A, IL‐22, TNF‐α, and oncostatin M). The migration and tube formation of HUVECs …

Cameron Nowell

Cameron Nowell

Monash University

The FASEB Journal

The pro‐resolving mediator, annexin A1 regulates blood pressure, and age‐associated changes in cardiovascular function and remodeling

Aging is associated with chronic, low‐level inflammation which may contribute to cardiovascular pathologies such as hypertension and atherosclerosis. This chronic inflammation may be opposed by endogenous mechanisms to limit inflammation, for example, by the actions of annexin A1 (ANXA1), an endogenous glucocorticoid‐regulated protein that has anti‐inflammatory and pro‐resolving activity. We hypothesized the pro‐resolving mediator ANXA1 protects against age‐induced changes in blood pressure (BP), cardiovascular structure and function, and cardiac senescence. BP was measured monthly in conscious mature (4‐month) and middle‐aged (12‐month) ANXA1‐deficient (ANXA1−/−) and wild‐type C57BL/6 mice. Body composition was measured using EchoMRI, and both cardiac and vascular function using ultrasound imaging. Cardiac hypertrophy, fibrosis and senescence, vascular fibrosis, elastin …

Taha Azad

Taha Azad

Queen's University

The FASEB Journal

Hydrogen peroxide sensitivity connects the activity of COX5A and NPR3 to the regulation of YAP1 expression

Reactive oxygen species (ROS) are among the most severe types of cellular stressors with the ability to damage essential cellular biomolecules. Excess levels of ROS are correlated with multiple pathophysiological conditions including neurodegeneration, diabetes, atherosclerosis, and cancer. Failure to regulate the severely imbalanced levels of ROS can ultimately lead to cell death, highlighting the importance of investigating the molecular mechanisms involved in the detoxification procedures that counteract the effects of these compounds in living organisms. One of the most abundant forms of ROS is H2O2, mainly produced by the electron transport chain in the mitochondria. Numerous genes have been identified as essential to the process of cellular detoxification. Yeast YAP1, which is homologous to mammalian AP‐1 type transcriptional factors, has a key role in oxidative detoxification by upregulating the …

Shemin Lu (吕社民)

Shemin Lu (吕社民)

Xi'an Jiaotong University

The FASEB Journal

IL‐21 promoting angiogenesis contributes to the development of psoriasis

Background Elevated IL‐21 expression which can effectively induce Th17 cell differentiation has been implicated in the pathogenesis of psoriasis, but its role in angiogenesis remains poorly understood. Methods PASI and PSI score assessment was applied to evaluate the severity of psoriatic lesions. The expression of IL‐21, IL‐21 receptor (IL‐21R), CD31, VEGFA, MMP‐9, and ICAM‐1 in skin was determined by immunohistochemistry or quantitative real‐time polymerase chain reaction. The serum level of IL‐21 was measured by enzyme‐linked immunosorbent assay (ELISA). Then, their correlation was analyzed statistically. Human umbilical vein endothelial cells (HUVECs) cocultured with conditional medium from normal human epidermal keratinocytes (NHEKs) were treated with IL‐21 and/or M5 cocktail (mixture of IL‐1α, IL‐17A, IL‐22, TNF‐α, and oncostatin M). The migration and tube formation of HUVECs …

Michelle E. Armstrong, Ph.D.

Michelle E. Armstrong, Ph.D.

Trinity College

The FASEB Journal

The human MIF polymorphism CATT7 enhances pro‐inflammatory macrophage polarization in a clinically relevant model of allergic airway inflammation

High level expression of the pro‐inflammatory cytokine macrophage migration inhibitory factor (MIF) has been associated with severe asthma. The role of MIF and its functional promotor polymorphism in innate immune training is currently unknown. Using novel humanized CATT7 MIF mice, this study is the first to investigate the effect of MIF on bone marrow‐derived macrophage (BMDM) memory after house dust mite (HDM) challenge. CATT7 BMDMs demonstrated a significant primed increase in M1 markers following HDM and LPS stimulation, compared to naive mice. This M1 signature was found to be MIF‐dependent, as administration of a small molecule MIF inhibitor, SCD‐19, blocked the induction of this pro‐inflammatory M1‐like phenotype in BMDMs from CATT7 mice challenged with HDM. Training naive BMDMs in vitro with HDM for 24 h followed by a rest period and subsequent stimulation with LPS led …

Gabrielle Fredman

Gabrielle Fredman

Albany Medical College

The FASEB Journal

Resolvin D2 limits atherosclerosis progression via myeloid cell‐GPR18

Dysregulated inflammation‐resolution programs are associated with atherosclerosis progression. Resolvins, in part, mediate inflammation‐resolution programs. Indeed, Resolvin D2 (RvD2) activates GPR18, a G‐protein‐coupled receptor, and limits plaque progression, though the cellular targets of RvD2 remain unknown. Here, we developed a humanized GPR18 floxed (“fl/fl”) and a myeloid (Lysozyme M Cre) GPR18 knockout (mKO) mouse. We functionally validated this model by assessing efferocytosis in bone marrow‐derived macrophages (BMDMs) and found that RvD2 enhanced efferocytosis in the fl/fl, but not in the mKO BMDMs. To understand the functions of RvD2‐GPR18 in atherosclerosis, we performed a bone marrow transfer of fl/fl or mKO bone marrow into Ldlr−/− recipients. For these experiments, we treated each genotype with either Vehicle/PBS or RvD2 (25 ng/mouse, 3 times/week for 3 weeks …