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Williams CH, Neitzel LR, Cornell J, Rea S, Mills I, Silver MS, Ahmad JD, Birukov KG, Birukova A, Brem H, Tyler B, Bar EE, Hong CC. GPR68-ATF4 signaling is a novel prosurvival pathway in glioblastoma activated by acidic extracellular microenvironment. Exp Hematol Oncol 2024; 13:13. [PMID: 38291540 PMCID: PMC10829393 DOI: 10.1186/s40164-023-00468-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 12/25/2023] [Indexed: 02/01/2024] Open
Abstract
BACKGROUND Glioblastoma multiforme (GBM) stands as a formidable challenge in oncology because of its aggressive nature and severely limited treatment options. Despite decades of research, the survival rates for GBM remain effectively stagnant. A defining hallmark of GBM is a highly acidic tumor microenvironment, which is thought to activate pro-tumorigenic pathways. This acidification is the result of altered tumor metabolism favoring aerobic glycolysis, a phenomenon known as the Warburg effect. Low extracellular pH confers radioresistant tumors to glial cells. Notably GPR68, an acid sensing GPCR, is upregulated in radioresistant GBM. Usage of Lorazepam, which has off target agonism of GPR68, is linked to worse clinical outcomes for a variety of cancers. However, the role of tumor microenvironment acidification in GPR68 activation has not been assessed in cancer. Here we interrogate the role of GPR68 specifically in GBM cells using a novel highly specific small molecule inhibitor of GPR68 named Ogremorphin (OGM) to induce the iron mediated cell death pathway: ferroptosis. METHOD OGM was identified in a non-biased zebrafish embryonic development screen and validated with Morpholino and CRISPR based approaches. Next, A GPI-anchored pH reporter, pHluorin2, was stably expressed in U87 glioblastoma cells to probe extracellular acidification. Cell survival assays, via nuclei counting and cell titer glo, were used to demonstrate sensitivity to GPR68 inhibition in twelve immortalized and PDX GBM lines. To determine GPR68 inhibition's mechanism of cell death we use DAVID pathway analysis of RNAseq. Our major indication, ferroptosis, was then confirmed by western blotting and qRT-PCR of reporter genes including TFRC. This finding was further validated by transmission electron microscopy and liperfluo staining to assess lipid peroxidation. Lastly, we use siRNA and CRISPRi to demonstrate the critical role of ATF4 suppression via GPR68 for GBM survival. RESULTS We used a pHLourin2 probe to demonstrate how glioblastoma cells acidify their microenvironment to activate the commonly over expressed acid sensing GPCR, GPR68. Using our small molecule inhibitor OGM and genetic means, we show that blocking GPR68 signaling results in robust cell death in all thirteen glioblastoma cell lines tested, irrespective of genetic and phenotypic heterogeneity, or resistance to the mainstay GBM chemotherapeutic temozolomide. We use U87 and U138 glioblastoma cell lines to show how selective induction of ferroptosis occurs in an ATF4-dependent manner. Importantly, OGM was not-acutely toxic to zebrafish and its inhibitory effects were found to spare non-malignant neural cells. CONCLUSION These results indicate GPR68 emerges as a critical sensor for an autocrine pro-tumorigenic signaling cascade triggered by extracellular acidification in glioblastoma cells. In this context, GPR68 suppresses ATF4, inhibition of GPR68 increases expression of ATF4 which leads to ferroptotic cell death. These findings provide a promising therapeutic approach to selectively induce ferroptosis in glioblastoma cells while sparing healthy neural tissue.
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Affiliation(s)
- Charles H Williams
- Department of Medicine, Michigan State University College of Human Medicine, East Lansing, MI, USA
- Henry Ford Health + Michigan State Health Sciences, Detroit, MI, USA
| | - Leif R Neitzel
- Department of Medicine, Michigan State University College of Human Medicine, East Lansing, MI, USA
- Henry Ford Health + Michigan State Health Sciences, Detroit, MI, USA
| | - Jessica Cornell
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Samantha Rea
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ian Mills
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Maya S Silver
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jovanni D Ahmad
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Konstantin G Birukov
- Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Anna Birukova
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Henry Brem
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Betty Tyler
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Eli E Bar
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD, USA
- University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
| | - Charles C Hong
- Department of Medicine, Michigan State University College of Human Medicine, East Lansing, MI, USA.
- Henry Ford Health + Michigan State Health Sciences, Detroit, MI, USA.
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Chun YW, Miyamoto M, Williams CH, Neitzel LR, Silver-Isenstadt M, Cadar AG, Fuller DT, Fong DC, Liu H, Lease R, Kim S, Katagiri M, Durbin MD, Wang KC, Feaster TK, Sheng CC, Neely MD, Sreenivasan U, Cortes-Gutierrez M, Finn AV, Schot R, Mancini GMS, Ament SA, Ess KC, Bowman AB, Han Z, Bichell DP, Su YR, Hong CC. Impaired Reorganization of Centrosome Structure Underlies Human Infantile Dilated Cardiomyopathy. Circulation 2023; 147:1291-1303. [PMID: 36970983 PMCID: PMC10133173 DOI: 10.1161/circulationaha.122.060985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 02/22/2023] [Indexed: 03/29/2023]
Abstract
BACKGROUND During cardiomyocyte maturation, the centrosome, which functions as a microtubule organizing center in cardiomyocytes, undergoes dramatic structural reorganization where its components reorganize from being localized at the centriole to the nuclear envelope. This developmentally programmed process, referred to as centrosome reduction, has been previously associated with cell cycle exit. However, understanding of how this process influences cardiomyocyte cell biology, and whether its disruption results in human cardiac disease, remains unknown. We studied this phenomenon in an infant with a rare case of infantile dilated cardiomyopathy (iDCM) who presented with left ventricular ejection fraction of 18% and disrupted sarcomere and mitochondria structure. METHODS We performed an analysis beginning with an infant who presented with a rare case of iDCM. We derived induced pluripotent stem cells from the patient to model iDCM in vitro. We performed whole exome sequencing on the patient and his parents for causal gene analysis. CRISPR/Cas9-mediated gene knockout and correction in vitro were used to confirm whole exome sequencing results. Zebrafish and Drosophila models were used for in vivo validation of the causal gene. Matrigel mattress technology and single-cell RNA sequencing were used to characterize iDCM cardiomyocytes further. RESULTS Whole exome sequencing and CRISPR/Cas9 gene knockout/correction identified RTTN, the gene encoding the centrosomal protein RTTN (rotatin), as the causal gene underlying the patient's condition, representing the first time a centrosome defect has been implicated in a nonsyndromic dilated cardiomyopathy. Genetic knockdowns in zebrafish and Drosophila confirmed an evolutionarily conserved requirement of RTTN for cardiac structure and function. Single-cell RNA sequencing of iDCM cardiomyocytes showed impaired maturation of iDCM cardiomyocytes, which underlie the observed cardiomyocyte structural and functional deficits. We also observed persistent localization of the centrosome at the centriole, contrasting with expected programmed perinuclear reorganization, which led to subsequent global microtubule network defects. In addition, we identified a small molecule that restored centrosome reorganization and improved the structure and contractility of iDCM cardiomyocytes. CONCLUSIONS This study is the first to demonstrate a case of human disease caused by a defect in centrosome reduction. We also uncovered a novel role for RTTN in perinatal cardiac development and identified a potential therapeutic strategy for centrosome-related iDCM. Future study aimed at identifying variants in centrosome components may uncover additional contributors to human cardiac disease.
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Affiliation(s)
- Young Wook Chun
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland Medical Center, Baltimore, MD 21201
| | - Matthew Miyamoto
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland Medical Center, Baltimore, MD 21201
| | - Charles H. Williams
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland Medical Center, Baltimore, MD 21201
| | - Leif R. Neitzel
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland Medical Center, Baltimore, MD 21201
| | - Maya Silver-Isenstadt
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland Medical Center, Baltimore, MD 21201
| | - Adrian G. Cadar
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37201
| | - Daniela T. Fuller
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland Medical Center, Baltimore, MD 21201
| | - Daniel C. Fong
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland Medical Center, Baltimore, MD 21201
| | - Hanhan Liu
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland Medical Center, Baltimore, MD 21201
| | - Robert Lease
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sungseek Kim
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37201
| | - Mikako Katagiri
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37201
| | - Matthew D. Durbin
- Division of Neonatology-Perinatology, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 26202
| | - Kuo-Chen Wang
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland Medical Center, Baltimore, MD 21201
| | - Tromondae K. Feaster
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37201
| | - Calvin C. Sheng
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37201
| | - M. Diana Neely
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37201
| | - Urmila Sreenivasan
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland Medical Center, Baltimore, MD 21201
| | - Marcia Cortes-Gutierrez
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Aloke V. Finn
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland Medical Center, Baltimore, MD 21201
| | - Rachel Schot
- Division of Neonatology-Perinatology, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 26202
| | - Grazia M. S. Mancini
- Department of Clinical Genetics, Erasmus University Medical Center (Erasmus MC), P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Seth A. Ament
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kevin C. Ess
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN37201
| | - Aaron B. Bowman
- School of Health Sciences, Purdue University, West Lafayette, IN 47906
| | - Zhe Han
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland Medical Center, Baltimore, MD 21201
| | - David P. Bichell
- Department of Pediatric Cardiac Surgery, Vanderbilt University Medical Center, Nashville, TN 37201
| | - Yan Ru Su
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37201
| | - Charles C. Hong
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland Medical Center, Baltimore, MD 21201
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Williams CH, Neitzel LR, Cornell J, Rea S, Mills I, Silver-Isenstadt M, Ahmad JD, Brem H, Tyler B, Bar EE, Hong CC. Abstract 443: Therapeutic targeting of GPR68 activated by acidic extracellular microenvironment induces ferroptosis in glioblastoma cells. Cancer Res 2023. [DOI: 10.1158/1538-7445.am2023-443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
Abstract
Abstract
The Warburg Effect is a common feature of cancer cells characterized by increased glucose uptake and fermentation of glucose to lactate even in the presence of oxygen. While it is commonly accepted that Warburg Effect promotes the growth, survival, proliferation, and long-term maintenance of cancers, its precise function and its downstream mediators remain unclear. A key physiological consequence of the Warburg effect is lactate secretion, which acidifies the tumor milieu, thought to promote oncogenesis and confer tumor resistance to chemotherapy and radiotherapy. Glioblastoma multiforme (GBM) is one of the most aggressive and deadly cancers, characterized by cellular heterogeneity and plasticity, which are thought to drive extreme therapeutic resistance. Despite their heterogeneity, common hallmarks of GBM tumors are high levels of aerobic glycolysis (“Warburg Effect”) and a resultant acidic tumor microenvironment (TME), which promotes tumor progression. In an in vivo zebrafish developmental screen, we identified ogremorphin (OGM), a small molecule inhibitor of GPR68/OGR-1, a G-protein coupled receptor (GPCR) which is activated by extracellular protons. Using ogremorphin and pHluorin2-GPI, a novel sensor of extracellular acidification, we demonstrate that glioblastoma cells acidify their own environment in vitro and activate GPR68, and visualize, for the first time, the establishment of the acidic extracellular microenvironment during the formation of GBM spheroids in vitro. Selective inhibition of GPR68 causes robust cell death in all 12 glioblastoma cell lines tested to date, despite genetic and molecular heterogeneity, without toxicity on healthy cells in whole animals. Mechanistically, GPR68 inhibition activates ferroptosis, a programmed cell death characterized by lipid peroxidation, in an ATF4 (activating transcription factor 4)-dependent manner. Finally, in GBM cells, ogremorphin treatment demonstrates strong synergistic effects with the frontline therapeutics temozolomide and ionizing radiation. Our results indicate that GPR68 activation by extracellular acidification is a key cancer survival pathway downstream of the Warburg Effect, and that GPR68 inhibition, either alone or in combination with temozolomide and radiation therapy, is a promising therapeutic approach to selectively induce ferroptosis in GBM tumors.
Citation Format: Charles H. Williams, Leif R. Neitzel, Jessica Cornell, Samantha Rea, Ian Mills, Maya Silver-Isenstadt, Jovanni D. Ahmad, Henry Brem, Betty Tyler, Eli E. Bar, Charles C. Hong. Therapeutic targeting of GPR68 activated by acidic extracellular microenvironment induces ferroptosis in glioblastoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 443.
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Affiliation(s)
| | | | | | - Samantha Rea
- 1University of Maryland School of Medicine, Baltimore, MD
| | - Ian Mills
- 1University of Maryland School of Medicine, Baltimore, MD
| | | | | | - Henry Brem
- 2Johns Hopkins School of Medicine, Baltimore, MD
| | - Betty Tyler
- 2Johns Hopkins School of Medicine, Baltimore, MD
| | - Eli E. Bar
- 1University of Maryland School of Medicine, Baltimore, MD
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Alkhalfan F, Gyftopoulos A, Chen YJ, Williams CH, Perry JA, Hong CC. Identifying genetic variants associated with the ICD10 (International Classification of Diseases10)-based diagnosis of cerebrovascular disease using a large-scale biomedical database. PLoS One 2022; 17:e0273217. [PMID: 35994481 PMCID: PMC9394849 DOI: 10.1371/journal.pone.0273217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Accepted: 08/04/2022] [Indexed: 11/20/2022] Open
Abstract
OBJECTIVES To utilize the UK Biobank to identify genetic variants associated with the ICD10 (International Classification of Diseases10)-based diagnosis of cerebrovascular disease (CeVD). BACKGROUND Cerebrovascular disease occurs because of a complex interplay between vascular, environmental, and genetic factors. It is the second leading cause of disability worldwide. Understanding who may be genetically predisposed to cerebrovascular disease can help guide preventative efforts. Moreover, there is considerable interest in the use of real-world data, such as EHR (electronic health records) to better understand disease mechanisms and to discover new treatment strategies, but whether ICD10-based diagnosis can be used to study CeVD genetics is unknown. METHODS Using the UK Biobank, we conducted a genome-wide association study (GWAS) where we analyzed the genomes of 11,155 cases and 122,705 controls who were sex, age and ancestry-matched in a 1:11 case: control design. Genetic variants were identified by Plink's firth logistic regression and assessed for association with the ICD10 codes corresponding to CeVD. RESULTS We identified two groups of SNPs closely linked to PITX2 and LRRTM4 that were significantly associated with CeVD in this study (p < 5 x 10-8) and had a minor allele frequency of > 0.5%. DISCUSSION Disease assignment based on ICD10 codes may underestimate prevalence; however, for CeVD, this does not appear to be the case. Compared to the age- and sex-matched control population, individuals with CeVD were more frequently diagnosed with comorbid conditions, such as hypertension, hyperlipidemia & atrial fibrillation or flutter, confirming their contribution to CeVD. The UK Biobank based ICD10 study identified 2 groups of variants that were associated with CeVD. The association between PITX2 and CeVD is likely explained by the increased rates of atrial fibrillation and flutter. While the mechanism explaining the relationship between LRRTM4 and CeVD is unclear, this has been documented in previous studies.
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Affiliation(s)
- Fahad Alkhalfan
- University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Alex Gyftopoulos
- University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Yi-Ju Chen
- University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Charles H. Williams
- University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - James A. Perry
- University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Charles C. Hong
- University of Maryland School of Medicine, Baltimore, Maryland, United States of America
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Shen C, Nayak A, Neitzel LR, Yang F, Li B, Williams CH, Hong CC, Ahmed Y, Lee E, Robbins DJ. The Casein kinase 1α agonist pyrvinium attenuates Wnt-mediated CK1α degradation via interaction with the E3 ubiquitin ligase component Cereblon. J Biol Chem 2022; 298:102227. [PMID: 35780831 PMCID: PMC9352546 DOI: 10.1016/j.jbc.2022.102227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [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: 03/25/2022] [Revised: 06/23/2022] [Accepted: 06/27/2022] [Indexed: 12/04/2022] Open
Abstract
The Cullin-RING ligase 4 E3 ubiquitin ligase component Cereblon (CRBN) is a well-established target for a class of small molecules termed immunomodulatory drugs (IMiDs). These drugs drive CRBN to modulate the degradation of a number of neosubstrates required for the growth of multiple cancers. Whereas the mechanism underlying the activation of CRBN by IMiDs is well described, the normal physiological regulation of CRBN is poorly understood. We recently showed that CRBN is activated following exposure to Wnt ligands and subsequently mediates the degradation of a subset of physiological substrates. Among the Wnt-dependent substrates of CRBN is Casein kinase 1α (CK1α), a known negative regulator of Wnt signaling. Wnt-mediated degradation of CK1α occurs via its association with CRBN at a known IMiD binding pocket. Herein, we demonstrate that a small-molecule CK1α agonist, pyrvinium, directly prevents the Wnt-dependent interaction of CRBN with CK1α, attenuating the consequent CK1α degradation. We further show that pyrvinium disrupts the ability of CRBN to interact with CK1α at the IMiD binding pocket within the CRBN-CK1α complex. Of note, this function of pyrvinium is independent of its previously reported ability to enhance CK1α kinase activity. Furthermore, we also demonstrate that pyrvinium attenuates CRBN-induced Wnt pathway activation in vivo. Collectively, these results reveal a novel dual mechanism through which pyrvinium inhibits Wnt signaling by both attenuating the CRBN-mediated destabilization of CK1α and activating CK1α kinase activity.
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Affiliation(s)
- Chen Shen
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, District of Columbia, USA; Molecular Oncology Program, The DeWitt Daughtry Family Department of Surgery, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Anmada Nayak
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, District of Columbia, USA; Molecular Oncology Program, The DeWitt Daughtry Family Department of Surgery, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Leif R Neitzel
- Department of Medicine, University of Maryland, Baltimore, Maryland, USA
| | - Fan Yang
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, District of Columbia, USA; Molecular Oncology Program, The DeWitt Daughtry Family Department of Surgery, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Bin Li
- Molecular Oncology Program, The DeWitt Daughtry Family Department of Surgery, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Charles H Williams
- Department of Medicine, University of Maryland, Baltimore, Maryland, USA
| | - Charles C Hong
- Department of Medicine, University of Maryland, Baltimore, Maryland, USA
| | - Yashi Ahmed
- Department of Molecular and Systems Biology and the Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, USA
| | - Ethan Lee
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - David J Robbins
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, District of Columbia, USA.
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Gyftopoulos A, Chen YJ, Wang L, Williams CH, Chun YW, O’Connell JR, Perry JA, Hong CC. Identification of Novel Genetic Variants and Comorbidities Associated With ICD-10-Based Diagnosis of Hypertrophic Cardiomyopathy Using the UK Biobank Cohort. Front Genet 2022; 13:866042. [PMID: 35685441 PMCID: PMC9171016 DOI: 10.3389/fgene.2022.866042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 04/13/2022] [Indexed: 11/15/2022] Open
Abstract
Objectives: To identify previously unrecognized genetic variants and clinical variables associated with the ICD-10 (International Classification of Diseases 10)-based diagnosis of hypertrophic cardiomyopathy in the UK Biobank cohort. Background: Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiovascular disorder with more than 2000 known mutations in one of eight genes encoding sarcomeric proteins. However, there is considerable variation in disease manifestation, suggesting the role of additional unrecognized contributors, genetic and otherwise. There is substantial interest in the use of real-world data, such as electronic health records to better understand disease mechanisms and discover new treatment strategies, but whether ICD-10-based diagnosis can be used to study HCM genetics is unknown. Methods: In a genome-wide association study (GWAS) using the UK Biobank, we analyzed the genomes of 363 individuals diagnosed with HCM based on ICD-10 coding compared to 7,260 age, ancestry, and sex-matched controls in a 1:20 case:control design. Genetic variants were analyzed by Plink's firth logistic regression and assessed for association with HCM. We also examined 61 biomarkers and other diagnoses in the 363 HCM cases and matched controls. Results: The prevalence of ICD-10-based diagnosis of HCM in the UK Biobank cohort was 1 in 1,342, suggesting disease assignment based on the two ICD-10 codes underestimates HCM prevalence. In addition, common cardiovascular comorbidities were more prevalent in ICD-10-based HCM cases in comparison to controls. We identified two novel, non-sarcomeric genetic variants in KMT2C rs78630626, and PARD3B rs188937806 that were associated with ICD-10 codes for HCM with genome-wide significance (p < 5 x 10-8). These are associated with an increased odds ratio (OR) of ∼3.8 for being diagnosed with HCM. Minor allele frequency (MAF) of each variant was >1%. Discussion: Disease assignment based strictly on ICD-10 codes may underestimate HCM prevalence. Individuals with HCM were more frequently diagnosed with several comorbid conditions, such as hypertension, atherosclerotic heart disease, diabetes, and kidney failure, suggesting they may contribute to disease manifestation. This UK Biobank database-based GWAS identified common variants in KMT2C and PARD3B that are associated with HCM diagnosis, which may represent novel modifier genes. Our study demonstrates the feasibility and limitations of conducting phenotypic and genotypic characterization of HCM based on ICD-10 diagnosis in a large population-based cohort.
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Affiliation(s)
| | | | | | | | | | | | - James A. Perry
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Charles C. Hong
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States
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Karki P, Ke Y, Williams CH, Hong CC, Birukov KG, Birukova AA. GPR68 Inhibition with a Novel Group of Ogremorphin Inhibitors Upregulate Endothelial Barrier Function and Protect Against Bacterial Pathogens or Acidosis‐induced Inflammation in Lung Endothelium. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r4848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Pratap Karki
- Pulmonary and Critical Care MedicineUniversity of Maryland School of MedicineBaltimoreMD
| | - Yunbo Ke
- University of Maryland School of MedicineBaltimoreMD
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Shen C, Nayak A, Neitzel LR, Adams AA, Silver-Isenstadt M, Sawyer LM, Benchabane H, Wang H, Bunnag N, Li B, Wynn DT, Yang F, Garcia-Contreras M, Williams CH, Dakshanamurthy S, Hong CC, Ayad NG, Capobianco AJ, Ahmed Y, Lee E, Robbins DJ. The E3 ubiquitin ligase component, Cereblon, is an evolutionarily conserved regulator of Wnt signaling. Nat Commun 2021; 12:5263. [PMID: 34489457 PMCID: PMC8421366 DOI: 10.1038/s41467-021-25634-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 08/13/2021] [Indexed: 11/09/2022] Open
Abstract
Immunomodulatory drugs (IMiDs) are important for the treatment of multiple myeloma and myelodysplastic syndrome. Binding of IMiDs to Cereblon (CRBN), the substrate receptor of the CRL4CRBN E3 ubiquitin ligase, induces cancer cell death by targeting key neo-substrates for degradation. Despite this clinical significance, the physiological regulation of CRBN remains largely unknown. Herein we demonstrate that Wnt, the extracellular ligand of an essential signal transduction pathway, promotes the CRBN-dependent degradation of a subset of proteins. These substrates include Casein kinase 1α (CK1α), a negative regulator of Wnt signaling that functions as a key component of the β-Catenin destruction complex. Wnt stimulation induces the interaction of CRBN with CK1α and its resultant ubiquitination, and in contrast with previous reports does so in the absence of an IMiD. Mechanistically, the destruction complex is critical in maintaining CK1α stability in the absence of Wnt, and in recruiting CRBN to target CK1α for degradation in response to Wnt. CRBN is required for physiological Wnt signaling, as modulation of CRBN in zebrafish and Drosophila yields Wnt-driven phenotypes. These studies demonstrate an IMiD-independent, Wnt-driven mechanism of CRBN regulation and provide a means of controlling Wnt pathway activity by CRBN, with relevance for development and disease.
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Affiliation(s)
- Chen Shen
- Molecular Oncology Program, The DeWitt Daughtry Family Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL, USA.,The Sheila and David Fuente Graduate Program in Cancer Biology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Anmada Nayak
- Molecular Oncology Program, The DeWitt Daughtry Family Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Leif R Neitzel
- Department of Medicine, University of Maryland, Baltimore, MD, USA
| | - Amber A Adams
- Department of Molecular and Systems Biology and the Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth College, Hanover, NH, USA
| | | | - Leah M Sawyer
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Hassina Benchabane
- Department of Molecular and Systems Biology and the Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth College, Hanover, NH, USA
| | - Huilan Wang
- Molecular Oncology Program, The DeWitt Daughtry Family Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Nawat Bunnag
- Department of Molecular and Systems Biology and the Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth College, Hanover, NH, USA
| | - Bin Li
- Molecular Oncology Program, The DeWitt Daughtry Family Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Daniel T Wynn
- Molecular Oncology Program, The DeWitt Daughtry Family Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Fan Yang
- Molecular Oncology Program, The DeWitt Daughtry Family Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL, USA.,The Sheila and David Fuente Graduate Program in Cancer Biology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Marta Garcia-Contreras
- Molecular Oncology Program, The DeWitt Daughtry Family Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL, USA
| | | | - Sivanesan Dakshanamurthy
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | - Charles C Hong
- Department of Medicine, University of Maryland, Baltimore, MD, USA
| | - Nagi G Ayad
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA.,Center for Therapeutic Innovation, Department of Neurological Surgery, Miami Project to Cure Paralysis, Miller School of Medicine, University of Miami, Miami, FL, USA.,Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Anthony J Capobianco
- Molecular Oncology Program, The DeWitt Daughtry Family Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL, USA.,Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Yashi Ahmed
- Department of Molecular and Systems Biology and the Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth College, Hanover, NH, USA
| | - Ethan Lee
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - David J Robbins
- Molecular Oncology Program, The DeWitt Daughtry Family Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL, USA. .,Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA. .,Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, FL, USA.
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9
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Ashvetiya T, Fan SX, Chen YJ, Williams CH, O’Connell JR, Perry JA, Hong CC. Identification of novel genetic susceptibility loci for thoracic and abdominal aortic aneurysms via genome-wide association study using the UK Biobank Cohort. PLoS One 2021; 16:e0247287. [PMID: 34469433 PMCID: PMC8409653 DOI: 10.1371/journal.pone.0247287] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 06/25/2021] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Thoracic aortic aneurysm (TAA) and abdominal aortic aneurysm (AAA) are known to have a strong genetic component. METHODS AND RESULTS In a genome-wide association study (GWAS) using the UK Biobank, we analyzed the genomes of 1,363 individuals with AAA compared to 27,260 age, ancestry, and sex-matched controls (1:20 case:control study design). A similar analysis was repeated for 435 individuals with TAA compared to 8,700 controls. Polymorphism with minor allele frequency (MAF) >0.5% were evaluated. We identified novel loci near LINC01021, ATOH8 and JAK2 genes that achieved genome-wide significance for AAA (p-value <5x10-8), in addition to three known loci. For TAA, three novel loci in CTNNA3, FRMD6 and MBP achieved genome-wide significance. There was no overlap in the genes associated with AAAs and TAAs. Additionally, we identified a linkage group of high-frequency variants (MAFs ~10%) encompassing FBN1, the causal gene for Marfan syndrome, which was associated with TAA. In FinnGen PheWeb, this FBN1 haplotype was associated with aortic dissection. Finally, we found that baseline bradycardia was associated with TAA, but not AAA. CONCLUSIONS Our GWAS found that AAA and TAA were associated with distinct sets of genes, suggesting distinct underlying genetic architecture. We also found association between baseline bradycardia and TAA. These findings, including JAK2 association, offer plausible mechanistic and therapeutic insights. We also found a common FBN1 linkage group that is associated with TAA and aortic dissection in patients who do not have Marfan syndrome. These FBN1 variants suggest shared pathophysiology between Marfan disease and sporadic TAA.
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Affiliation(s)
- Tamara Ashvetiya
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Sherry X. Fan
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Yi-Ju Chen
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Charles H. Williams
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Jeffery R. O’Connell
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - James A. Perry
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Charles C. Hong
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
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10
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Engers DW, Bollinger SR, Felts AS, Vadukoot AK, Williams CH, Blobaum AL, Lindsley CW, Hong CC, Hopkins CR. Discovery, synthesis and characterization of a series of 7-aryl-imidazo[1,2-a]pyridine-3-ylquinolines as activin-like kinase (ALK) inhibitors. Bioorg Med Chem Lett 2020; 30:127418. [PMID: 32750526 PMCID: PMC7494637 DOI: 10.1016/j.bmcl.2020.127418] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [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: 06/25/2020] [Revised: 07/13/2020] [Accepted: 07/14/2020] [Indexed: 01/07/2023]
Abstract
The activin-like kinases are a family of kinases that play important roles in a variety of disease states. Of this class of kinases, ALK2, has been shown by a gain-of-function to be the primary driver of the childhood skeletal disease fibrodysplasia ossificans progressiva (FOP) and more recently the pediatric cancer diffuse intrinsic pontine glioma (DIPG). Herein, we report our efforts to identify a novel imidazo[1,2-a]pyridine scaffold as potent inhibitors of ALK2 with good in vivo pharmacokinetic properties suitable for future animal studies.
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Affiliation(s)
- Darren W Engers
- Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Sean R Bollinger
- Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Andrew S Felts
- Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Anish K Vadukoot
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-6125, USA
| | - Charles H Williams
- Division of Cardiovascular Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Anna L Blobaum
- Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Craig W Lindsley
- Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA; Department of Biochemistry, Vanderbilt University, Nashville, TN 37232, USA
| | - Charles C Hong
- Division of Cardiovascular Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Corey R Hopkins
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-6125, USA.
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11
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Gyftopoulos A, Ashvetiya T, Chen YJ, Wang L, Williams CH, Chun YW, Perry JA, Hong CC. Abstract 468: Previously Unrecognized Intronic Variants in the Dystrophin Gene Identified as Possible Contributors to Dilated Cardiomyopathy. Circ Res 2020. [DOI: 10.1161/res.127.suppl_1.468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Nonischemic dilated cardiomyopathy (DCM) often has a genetic etiology, however, its prevalence and etiologies are not completely understood. The UK Biobank comprises clinical and genetic data for greater than 500,000 individuals with enrollees 40-69 years of age. Our group created a custom phenotype of heart failure using ICD-10 codes for several subtypes of heart failure diagnoses including DCM. We then compared the individuals included in the custom heart failure phenotype to control individuals in a 20-to-1 fashion to identify genetic differences. Data were compared using Mixed Model Analysis for Pedigrees/Populations (MMAP) mixed-model regression. We identified 8 unlinked intronic variants in the dystrophin gene (
DMD
) that, when separated by self-identified race, occurred with a combined minor allele frequency of 0.15 in individuals with heart failure who identified as being of African descent. The combined minor allele frequency of these variants was 0.05 in individuals who self-identified as being of European descent. One variant of
DMD
in particular (rs139029250), was identified with a minor allele frequency of 0.05 in African British with DCM. The unadjusted odds ratio of a diagnosis of heart failure in individuals with rs129029250 was 4.65. When separated by gender, the unadjusted odds ratios are 2.02 for females and 6.44 for males.
DMD
is most notably known for its role in Duchenne and Becker muscular dystrophy, both of which are known to cause dilated cardiomyopathy in affected individuals. However, none of the individuals (36 female and 43 male) identified in our analysis with rs129029250 have been diagnosed with Duchenne muscular dystrophy, Becker muscular dystrophy, or a primary disorder of muscle (ICD code G70). Additionally, these individuals have an intronic variant of
DMD
, while Duchene and Becker muscular dystrophy are both due to exonic mutations. These findings suggest a possible common variant in the DMD gene that may contribute to DCM in individuals of African descent.
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Affiliation(s)
| | | | | | - Libin Wang
- Univ of Maryland Sch of Medicine, Baltimore, MD
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12
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Gyftopoulos A, Chen YJ, Wang L, Williams CH, Chun YW, Perry JA, Hong CC. Abstract 460: Cyclin Dependent Kinase Inhibitor A1 Identified as a Potential Risk Locus for Hypertrophic Cardiomyopathy. Circ Res 2020. [DOI: 10.1161/res.127.suppl_1.460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) is characterized by heterogeneous phenotypic expression, natural history, and genetic profile with numerous causative mutations. The relationship between genotype and phenotype in HCM is incompletely understood. Identifying genetic modifiers may expand understanding of the signaling pathways that are responsible for phenotypic expression. UK Biobank comprises clinical and genetic data for greater than 500,000 individuals. We compared control individuals to those with a diagnosis of HCM (identified via ICD-10 code I42.1) in a 20-to-1 fashion to identify genetic differences. Data were compared using Mixed Model Analysis for Pedigrees/Populations (MMAP) mixed-model regression. Variants were assessed using bioinformatics tools including linkage disequilibrium and Eigen scoring. Results were then compared to previously published genome-wide association datasets. Mixed-model regression identified 5 variants of cyclin-dependent kinase inhibitor 1A (
CDKN1A
) as statistically significant with one intronic variant (rs3176326) likely affecting a gene promoter region with an Eigen-PC score of 7.779. This variant was found to have a p-value of 5.08x10
-8
when contrasted to controls with a minor allele frequency of 0.199 in the affected individuals. The 4 other variants were in linkage disequilibrium (r
2
0.90-0.99) with rs3176326. The odds ratio of HCM with rs3176326 is 1.81.To our knowledge,
CDKN1A
has not previously been associated with HCM. By utilizing bioinformatic tools we were able to identify 5 variants that may be associated with the risk for HCM. One locus affects a promotor region and resulted in a notably high Eigan-PC score suggestive that it has an impact on HCM. When comparing these findings with previous genome-wide association studies utilizing the UK Biobank, we find that
CDKN1A
has a possible association with HCM, though those results were not statistically significant.
CDKN1A
has been previously associated with the p53 DNA repair and cell senescence pathway. Animal and human studies have implicated it in the development of fibrosis. A recent genome-wide association metanalysis identified it as a risk locus for heart failure. These findings support our conclusion that
CDKN1A
is a risk locus for HCM.
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Affiliation(s)
| | | | - Libin Wang
- Univ of Maryland Sch of Medicine, Baltimore, MD
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13
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Hankinson SJ, Williams CH, Ton VK, Gottlieb SS, Hong CC. Should we overcome the resistance to bioelectrical impedance in heart failure? Expert Rev Med Devices 2020; 17:785-794. [PMID: 32658589 DOI: 10.1080/17434440.2020.1791701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Heart failure is associated with increased neurohormonal activation that results in changes in body composition including volume overload and the loss of skeletal muscle, body fat, and bone density. Bioelectrical impedance measures body composition based on the conduction of electrical current through body fluids. AREAS COVERED The PubMed and Scopus databases were reviewed up to the third week of June 2020. Cross-sectional studies, retrospective observational studies, prospective observational studies, and randomized controlled trials have examined numerous bioelectrical impedance monitoring strategies to guide the diagnosis, prognosis, and treatment of heart failure. These monitoring strategies include intrathoracic impedance, lung impedance, bioelectrical impedance vector analysis, leg bioelectrical impedance, and thoracic bioreactance. EXPERT COMMENTARY Based on the current evidence, more studies are needed to validate bioelectrical impedance in heart failure. Lung impedance appears to be useful for guiding heart failure treatment in patients with ST-elevation myocardial infarction and improving outcomes in outpatients with heart failure. Furthermore, bioelectrical impedance has potential as a noninvasive, quantitative heart failure variable for population-based research.
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Affiliation(s)
- Stephen J Hankinson
- Department of Medicine, Division of Cardiovascular Medicine, University of Maryland School of Medicine , Baltimore, MD, USA
| | - Charles H Williams
- Department of Medicine, Division of Cardiovascular Medicine, University of Maryland School of Medicine , Baltimore, MD, USA
| | - Van-Khue Ton
- Department of Medicine, Division of Cardiovascular Medicine, University of Maryland School of Medicine , Baltimore, MD, USA.,Harvard Medical School, Division of Cardiology, Massachusetts General Hospital , Boston, MA, USA
| | - Stephen S Gottlieb
- Department of Medicine, Division of Cardiovascular Medicine, University of Maryland School of Medicine , Baltimore, MD, USA
| | - Charles C Hong
- Department of Medicine, Division of Cardiovascular Medicine, University of Maryland School of Medicine , Baltimore, MD, USA
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14
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Williams CH. A REVIEW: MALIGNANT HYPERTHERMIA‐A GENETIC DISEASE OF SODIUM CHANNEL FUNCTION. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.04142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Haycook CP, Balsamo JA, Glass EB, Williams CH, Hong CC, Major AS, Giorgio TD. PEGylated PLGA Nanoparticle Delivery of Eggmanone for T Cell Modulation: Applications in Rheumatic Autoimmunity. Int J Nanomedicine 2020; 15:1215-1228. [PMID: 32110018 PMCID: PMC7036983 DOI: 10.2147/ijn.s234850] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [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: 10/16/2019] [Accepted: 12/19/2019] [Indexed: 12/16/2022] Open
Abstract
Background Helper T cell activity is dysregulated in a number of diseases including those associated with rheumatic autoimmunity. Treatment options are limited and usually consist of systemic immune suppression, resulting in undesirable consequences from compromised immunity. Hedgehog (Hh) signaling has been implicated in the activation of T cells and the formation of the immune synapse, but remains understudied in the context of autoimmunity. Modulation of Hh signaling has the potential to enable controlled immunosuppression but a potential therapy has not yet been developed to leverage this opportunity. Methods In this work, we developed biodegradable nanoparticles to enable targeted delivery of eggmanone (Egm), a specific Hh inhibitor, to CD4+ T cell subsets. We utilized two FDA-approved polymers, poly(lactic-co-glycolic acid) and polyethylene glycol, to generate hydrolytically degradable nanoparticles. Furthermore, we employed maleimide-thiol mediated conjugation chemistry to decorate nanoparticles with anti-CD4 F(ab') antibody fragments to enable targeted delivery of Egm. Results Our novel delivery system achieved a highly specific association with the majority of CD4+ T cells present among a complex cell population. Additionally, we have demonstrated antigen-specific inhibition of CD4+ T cell responses mediated by nanoparticle-formulated Egm. Conclusion This work is the first characterization of Egm's immunomodulatory potential. Importantly, this study also suggests the potential benefit of a biodegradable delivery vehicle that is rationally designed for preferential interaction with a specific immune cell subtype for targeted modulation of Hh signaling.
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Affiliation(s)
- Christopher P Haycook
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Joseph A Balsamo
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA.,Department of Medicine, Division of Rheumatology and Immunology, Vanderbilt Medical Center, Nashville, TN 37232, USA
| | - Evan B Glass
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Charles H Williams
- Department of Medicine, Division of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Charles C Hong
- Department of Medicine, Division of Cardiovascular Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Amy S Major
- Department of Medicine, Division of Rheumatology and Immunology, Vanderbilt Medical Center, Nashville, TN 37232, USA.,U.S., Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN 37212, USA
| | - Todd D Giorgio
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
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16
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Williams CH, Hong CC. BMPing Up Healing Capacity with FKBP12 Ligand. Cell Chem Biol 2020; 26:619-620. [PMID: 31100260 DOI: 10.1016/j.chembiol.2019.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
While the wound healing property of the macrolide FK506 is well known, the underlying mechanism has been elusive. In this issue of Cell Chemical Biology, Peiffer et al. (2019) utilize FKBP12 ligand to demonstrate that wound healing effects of FK506 occur via activation of the BMP (bone morphogenic protein) signaling pathway.
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Affiliation(s)
- Charles H Williams
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Charles C Hong
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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17
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Williams CH. Malignant Hyperthermia: A secondary factor, i.e., intense peripheral vasoconstriction, drives heat retention. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.828.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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18
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Williams CH, Hong CC. Zebrafish small molecule screens: Taking the phenotypic plunge. Comput Struct Biotechnol J 2016; 14:350-356. [PMID: 27721960 PMCID: PMC5050293 DOI: 10.1016/j.csbj.2016.09.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [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: 06/27/2016] [Revised: 09/12/2016] [Accepted: 09/13/2016] [Indexed: 12/27/2022] Open
Abstract
Target based chemical screens are a mainstay of modern drug discovery, but the effectiveness of this reductionist approach is being questioned in light of declines in pharmaceutical R & D efficiency. In recent years, phenotypic screens have gained increasing acceptance as a complementary/alternative approach to early drug discovery. We discuss the various model organisms used in phenotypic screens, with particular focus on zebrafish, which has emerged as a leading model of in vivo phenotypic screens. Additionally, we anticipate therapeutic opportunities, particularly in orphan disease space, in the context of rapid advances in human Mendelian genetics, electronic health record (EHR)-enabled genome–phenome associations, and genome editing.
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Affiliation(s)
- Charles H Williams
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Charles C Hong
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Research Medicine, Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN 37212, USA
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19
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Affiliation(s)
- C H Williams
- Department of Mental Health, Queen's University, Belfast
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20
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Herington JL, Swale DR, Brown N, Shelton EL, Choi H, Williams CH, Hong CC, Paria BC, Denton JS, Reese J. High-Throughput Screening of Myometrial Calcium-Mobilization to Identify Modulators of Uterine Contractility. PLoS One 2015; 10:e0143243. [PMID: 26600013 PMCID: PMC4658040 DOI: 10.1371/journal.pone.0143243] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Accepted: 11/02/2015] [Indexed: 12/27/2022] Open
Abstract
The uterine myometrium (UT-myo) is a therapeutic target for preterm labor, labor induction, and postpartum hemorrhage. Stimulation of intracellular Ca2+-release in UT-myo cells by oxytocin is a final pathway controlling myometrial contractions. The goal of this study was to develop a dual-addition assay for high-throughput screening of small molecular compounds, which could regulate Ca2+-mobilization in UT-myo cells, and hence, myometrial contractions. Primary murine UT-myo cells in 384-well plates were loaded with a Ca2+-sensitive fluorescent probe, and then screened for inducers of Ca2+-mobilization and inhibitors of oxytocin-induced Ca2+-mobilization. The assay exhibited robust screening statistics (Z´ = 0.73), DMSO-tolerance, and was validated for high-throughput screening against 2,727 small molecules from the Spectrum, NIH Clinical I and II collections of well-annotated compounds. The screen revealed a hit-rate of 1.80% for agonist and 1.39% for antagonist compounds. Concentration-dependent responses of hit-compounds demonstrated an EC50 less than 10μM for 21 hit-antagonist compounds, compared to only 7 hit-agonist compounds. Subsequent studies focused on hit-antagonist compounds. Based on the percent inhibition and functional annotation analyses, we selected 4 confirmed hit-antagonist compounds (benzbromarone, dipyridamole, fenoterol hydrobromide and nisoldipine) for further analysis. Using an ex vivo isometric contractility assay, each compound significantly inhibited uterine contractility, at different potencies (IC50). Overall, these results demonstrate for the first time that high-throughput small-molecules screening of myometrial Ca2+-mobilization is an ideal primary approach for discovering modulators of uterine contractility.
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Affiliation(s)
- Jennifer L. Herington
- Department of Pediatrics, Division of Neonatology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- * E-mail:
| | - Daniel R. Swale
- Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, United States of America
| | - Naoko Brown
- Department of Pediatrics, Division of Neonatology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Elaine L. Shelton
- Department of Pediatrics, Division of Neonatology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Hyehun Choi
- Department of Pediatrics, Division of Critical Care Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Charles H. Williams
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Charles C. Hong
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Bibhash C. Paria
- Department of Pediatrics, Division of Neonatology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Jerod S. Denton
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Jeff Reese
- Department of Pediatrics, Division of Neonatology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
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21
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Feaster TK, Cadar AG, Wang L, Williams CH, Chun YW, Hempel JE, Bloodworth N, Merryman WD, Lim CC, Wu JC, Knollmann BC, Hong CC. Matrigel Mattress: A Method for the Generation of Single Contracting Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Circ Res 2015; 117:995-1000. [PMID: 26429802 DOI: 10.1161/circresaha.115.307580] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 10/01/2015] [Indexed: 11/16/2022]
Abstract
RATIONALE The lack of measurable single-cell contractility of human-induced pluripotent stem cell-derived cardiac myocytes (hiPSC-CMs) currently limits the utility of hiPSC-CMs for evaluating contractile performance for both basic research and drug discovery. OBJECTIVE To develop a culture method that rapidly generates contracting single hiPSC-CMs and allows quantification of cell shortening with standard equipment used for studying adult CMs. METHODS AND RESULTS Single hiPSC-CMs were cultured for 5 to 7 days on a 0.4- to 0.8-mm thick mattress of undiluted Matrigel (mattress hiPSC-CMs) and compared with hiPSC-CMs maintained on a control substrate (<0.1-mm thick 1:60 diluted Matrigel, control hiPSC-CMs). Compared with control hiPSC-CMs, mattress hiPSC-CMs had more rod-shape morphology and significantly increased sarcomere length. Contractile parameters of mattress hiPSC-CMs measured with video-based edge detection were comparable with those of freshly isolated adult rabbit ventricular CMs. Morphological and contractile properties of mattress hiPSC-CMs were consistent across cryopreserved hiPSC-CMs generated independently at another institution. Unlike control hiPSC-CMs, mattress hiPSC-CMs display robust contractile responses to positive inotropic agents, such as myofilament calcium sensitizers. Mattress hiPSC-CMs exhibit molecular changes that include increased expression of the maturation marker cardiac troponin I and significantly increased action potential upstroke velocity because of a 2-fold increase in sodium current (INa). CONCLUSIONS The Matrigel mattress method enables the rapid generation of robustly contracting hiPSC-CMs and enhances maturation. This new method allows quantification of contractile performance at the single-cell level, which should be valuable to disease modeling, drug discovery, and preclinical cardiotoxicity testing.
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Affiliation(s)
- Tromondae K Feaster
- From the Departments of Pharmacology (T.K.F.), Cardiovascular Medicine (Y.W.C., J.E.H., C.C.L., C.C.H.), and Department of Medicine, Divisions of Cardiovascular Medicine and Clinical Pharmacology, Oates Institute for Experimental Therapeutics (L.W., B.C.K.), Department of Molecular Physiology and Biophysics (A.G.C.), Vanderbilt University School of Medicine, Nashville, TN; Departments of Cell and Developmental Biology (C.H.W.) and Biomedical Engineering (N.B., W.D.M.), Vanderbilt University, Nashville, TN; Research Medicine, Veterans Affairs TVHS, Nashville, TN (C.C.H.); and Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiology and Department of Radiology, Stanford University School of Medicine, CA (J.C.W.)
| | - Adrian G Cadar
- From the Departments of Pharmacology (T.K.F.), Cardiovascular Medicine (Y.W.C., J.E.H., C.C.L., C.C.H.), and Department of Medicine, Divisions of Cardiovascular Medicine and Clinical Pharmacology, Oates Institute for Experimental Therapeutics (L.W., B.C.K.), Department of Molecular Physiology and Biophysics (A.G.C.), Vanderbilt University School of Medicine, Nashville, TN; Departments of Cell and Developmental Biology (C.H.W.) and Biomedical Engineering (N.B., W.D.M.), Vanderbilt University, Nashville, TN; Research Medicine, Veterans Affairs TVHS, Nashville, TN (C.C.H.); and Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiology and Department of Radiology, Stanford University School of Medicine, CA (J.C.W.)
| | - Lili Wang
- From the Departments of Pharmacology (T.K.F.), Cardiovascular Medicine (Y.W.C., J.E.H., C.C.L., C.C.H.), and Department of Medicine, Divisions of Cardiovascular Medicine and Clinical Pharmacology, Oates Institute for Experimental Therapeutics (L.W., B.C.K.), Department of Molecular Physiology and Biophysics (A.G.C.), Vanderbilt University School of Medicine, Nashville, TN; Departments of Cell and Developmental Biology (C.H.W.) and Biomedical Engineering (N.B., W.D.M.), Vanderbilt University, Nashville, TN; Research Medicine, Veterans Affairs TVHS, Nashville, TN (C.C.H.); and Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiology and Department of Radiology, Stanford University School of Medicine, CA (J.C.W.)
| | - Charles H Williams
- From the Departments of Pharmacology (T.K.F.), Cardiovascular Medicine (Y.W.C., J.E.H., C.C.L., C.C.H.), and Department of Medicine, Divisions of Cardiovascular Medicine and Clinical Pharmacology, Oates Institute for Experimental Therapeutics (L.W., B.C.K.), Department of Molecular Physiology and Biophysics (A.G.C.), Vanderbilt University School of Medicine, Nashville, TN; Departments of Cell and Developmental Biology (C.H.W.) and Biomedical Engineering (N.B., W.D.M.), Vanderbilt University, Nashville, TN; Research Medicine, Veterans Affairs TVHS, Nashville, TN (C.C.H.); and Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiology and Department of Radiology, Stanford University School of Medicine, CA (J.C.W.)
| | - Young Wook Chun
- From the Departments of Pharmacology (T.K.F.), Cardiovascular Medicine (Y.W.C., J.E.H., C.C.L., C.C.H.), and Department of Medicine, Divisions of Cardiovascular Medicine and Clinical Pharmacology, Oates Institute for Experimental Therapeutics (L.W., B.C.K.), Department of Molecular Physiology and Biophysics (A.G.C.), Vanderbilt University School of Medicine, Nashville, TN; Departments of Cell and Developmental Biology (C.H.W.) and Biomedical Engineering (N.B., W.D.M.), Vanderbilt University, Nashville, TN; Research Medicine, Veterans Affairs TVHS, Nashville, TN (C.C.H.); and Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiology and Department of Radiology, Stanford University School of Medicine, CA (J.C.W.)
| | - Jonathan E Hempel
- From the Departments of Pharmacology (T.K.F.), Cardiovascular Medicine (Y.W.C., J.E.H., C.C.L., C.C.H.), and Department of Medicine, Divisions of Cardiovascular Medicine and Clinical Pharmacology, Oates Institute for Experimental Therapeutics (L.W., B.C.K.), Department of Molecular Physiology and Biophysics (A.G.C.), Vanderbilt University School of Medicine, Nashville, TN; Departments of Cell and Developmental Biology (C.H.W.) and Biomedical Engineering (N.B., W.D.M.), Vanderbilt University, Nashville, TN; Research Medicine, Veterans Affairs TVHS, Nashville, TN (C.C.H.); and Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiology and Department of Radiology, Stanford University School of Medicine, CA (J.C.W.)
| | - Nathaniel Bloodworth
- From the Departments of Pharmacology (T.K.F.), Cardiovascular Medicine (Y.W.C., J.E.H., C.C.L., C.C.H.), and Department of Medicine, Divisions of Cardiovascular Medicine and Clinical Pharmacology, Oates Institute for Experimental Therapeutics (L.W., B.C.K.), Department of Molecular Physiology and Biophysics (A.G.C.), Vanderbilt University School of Medicine, Nashville, TN; Departments of Cell and Developmental Biology (C.H.W.) and Biomedical Engineering (N.B., W.D.M.), Vanderbilt University, Nashville, TN; Research Medicine, Veterans Affairs TVHS, Nashville, TN (C.C.H.); and Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiology and Department of Radiology, Stanford University School of Medicine, CA (J.C.W.)
| | - W David Merryman
- From the Departments of Pharmacology (T.K.F.), Cardiovascular Medicine (Y.W.C., J.E.H., C.C.L., C.C.H.), and Department of Medicine, Divisions of Cardiovascular Medicine and Clinical Pharmacology, Oates Institute for Experimental Therapeutics (L.W., B.C.K.), Department of Molecular Physiology and Biophysics (A.G.C.), Vanderbilt University School of Medicine, Nashville, TN; Departments of Cell and Developmental Biology (C.H.W.) and Biomedical Engineering (N.B., W.D.M.), Vanderbilt University, Nashville, TN; Research Medicine, Veterans Affairs TVHS, Nashville, TN (C.C.H.); and Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiology and Department of Radiology, Stanford University School of Medicine, CA (J.C.W.)
| | - Chee Chew Lim
- From the Departments of Pharmacology (T.K.F.), Cardiovascular Medicine (Y.W.C., J.E.H., C.C.L., C.C.H.), and Department of Medicine, Divisions of Cardiovascular Medicine and Clinical Pharmacology, Oates Institute for Experimental Therapeutics (L.W., B.C.K.), Department of Molecular Physiology and Biophysics (A.G.C.), Vanderbilt University School of Medicine, Nashville, TN; Departments of Cell and Developmental Biology (C.H.W.) and Biomedical Engineering (N.B., W.D.M.), Vanderbilt University, Nashville, TN; Research Medicine, Veterans Affairs TVHS, Nashville, TN (C.C.H.); and Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiology and Department of Radiology, Stanford University School of Medicine, CA (J.C.W.)
| | - Joseph C Wu
- From the Departments of Pharmacology (T.K.F.), Cardiovascular Medicine (Y.W.C., J.E.H., C.C.L., C.C.H.), and Department of Medicine, Divisions of Cardiovascular Medicine and Clinical Pharmacology, Oates Institute for Experimental Therapeutics (L.W., B.C.K.), Department of Molecular Physiology and Biophysics (A.G.C.), Vanderbilt University School of Medicine, Nashville, TN; Departments of Cell and Developmental Biology (C.H.W.) and Biomedical Engineering (N.B., W.D.M.), Vanderbilt University, Nashville, TN; Research Medicine, Veterans Affairs TVHS, Nashville, TN (C.C.H.); and Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiology and Department of Radiology, Stanford University School of Medicine, CA (J.C.W.)
| | - Björn C Knollmann
- From the Departments of Pharmacology (T.K.F.), Cardiovascular Medicine (Y.W.C., J.E.H., C.C.L., C.C.H.), and Department of Medicine, Divisions of Cardiovascular Medicine and Clinical Pharmacology, Oates Institute for Experimental Therapeutics (L.W., B.C.K.), Department of Molecular Physiology and Biophysics (A.G.C.), Vanderbilt University School of Medicine, Nashville, TN; Departments of Cell and Developmental Biology (C.H.W.) and Biomedical Engineering (N.B., W.D.M.), Vanderbilt University, Nashville, TN; Research Medicine, Veterans Affairs TVHS, Nashville, TN (C.C.H.); and Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiology and Department of Radiology, Stanford University School of Medicine, CA (J.C.W.).
| | - Charles C Hong
- From the Departments of Pharmacology (T.K.F.), Cardiovascular Medicine (Y.W.C., J.E.H., C.C.L., C.C.H.), and Department of Medicine, Divisions of Cardiovascular Medicine and Clinical Pharmacology, Oates Institute for Experimental Therapeutics (L.W., B.C.K.), Department of Molecular Physiology and Biophysics (A.G.C.), Vanderbilt University School of Medicine, Nashville, TN; Departments of Cell and Developmental Biology (C.H.W.) and Biomedical Engineering (N.B., W.D.M.), Vanderbilt University, Nashville, TN; Research Medicine, Veterans Affairs TVHS, Nashville, TN (C.C.H.); and Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiology and Department of Radiology, Stanford University School of Medicine, CA (J.C.W.).
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22
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Feaster TK, Hempel JE, Williams CH, Frist AY, Hwang HS, Knollmann BC, Hong CC. Abstract 66: Discovery of a Novel Pharmaceutical Class as Potential Heart Failure Treatment. Circ Res 2015. [DOI: 10.1161/res.117.suppl_1.66] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Utilizing an unbiased
in vivo
phenotypic chemical screening platform in zebrafish embryos, our laboratory has identified a number of novel compounds with high selectivity for a wide range of cellular targets, including kinases (CK2a, DRAK2, DYRK2 and bone morphogenetic protein receptors), GPCRs (lysophosphatidic acid receptor 1, and extracellular proton sensor), p300 histone acetyltransferase, and phosphodiesterase-4 (PDE4). While the compounds we discovered have therapeutic implications for a wide range of diseases, our translational work has focused on addressing the cardiovascular diseases. Heart failure (HF) is a leading cause of disability and mortality in US, affecting about 6 million Americans, and the incidence of heart failure is anticipated to increase substantially in the coming decades. Yet, current HF pharmaceuticals are palliative, and the outlook for HF drug pipeline is uncertain. Within this backdrop, we recently discovered eggmanone, an extraordinarily selective PDE4 inhibitor which has no known off-target. An usual feature of eggmanone is that it increases cAMP levels specifically in distinct cellular microdomains, without raising the total cellular cAMP content. In isolated mouse cardiomyocytes and human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), eggmanone increases cardiac contractility by targeting a discrete myocyte microdomain without causing significant changes in myocyte calcium cycling. Importantly, eggmanone enhances systolic function in mice with failing hearts without increasing the heart rate. These results raise the exciting possibility that a microdomain-specific PDE4 inhibitor like eggmanone may be useful as an inotropic therapy for HF which avoids the pitfalls of traditional PDE inhibitors, whose utility has been limited by proarrhythmia, tachyphylaxis and cardiotoxicity.
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23
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Feaster TK, Williams CH, Cadar AG, Chun YW, Wang L, Bloodworth NC, Merryman WD, Lim CC, Knollmann BC, Hong CC. Abstract 156: Hydrogel Mattress, an in vitro Platform to Enhance Maturation and Evaluate Contractile Function of Individual hiPSC-CMs. Circ Res 2015. [DOI: 10.1161/res.117.suppl_1.156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) have great potential as tools for human heart disease modeling and drug discovery. However, their contractile properties have not been routinely evaluated; as current methods are not accessible for most laboratories. We sought to develop a more efficient method to evaluate hiPSC-CM mechanical properties, at the single cell level. Individual hiPSC-CMs were cultured on a hydrogel based platform, termed the “hydrogel mattress,” and their cellular contractile properties evaluated using video-based edge detection. We found that hiPSC-CMs maintained on the mattress reproducibly exhibited robust cell shortening, in dramatic contrast to hiPSC-CMs maintained in a standard manner. We further found that contraction and peak cell shortening amplitude of hiPSC-CMs on mattress was comparable to that of freshly isolated adult ventricular mouse CM. Importantly, hiPSC-CMs maintained on the mattress exhibited several characteristics of a native CM, in terms of myocyte elongation, calcium handling and pharmacological response. Finally, using this platform, we could calculate the traction force generated by individual CMs. In summary, the Hydrogel mattress platform is a simple and reliable
in vitro
platform that not only enables the quantification of contractile performance of isolated hiPSC-CMs, but also enhances CM maturation. This flexible platform can be extended to
in vitro
disease modeling, drug discovery and cardiotoxicity testing.
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Affiliation(s)
| | | | | | | | - Lili Wang
- Vanderbilt Univ Sch Medicine, Nashville, TN
| | | | | | - Chee C Lim
- Vanderbilt Univ Sch Medicine, Nashville, TN
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24
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Chun YW, Balikov DA, Feaster TK, Williams CH, Sheng CC, Lee JB, Boire TC, Neely MD, Bellan LM, Ess KC, Bowman AB, Sung HJ, Hong CC. Combinatorial polymer matrices enhance in vitro maturation of human induced pluripotent stem cell-derived cardiomyocytes. Biomaterials 2015. [PMID: 26204225 DOI: 10.1016/j.biomaterials.2015.07.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [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] [Indexed: 01/28/2023]
Abstract
Cardiomyocytes derived from human induced pluripotent stem cells (iPSC-CMs) hold great promise for modeling human heart diseases. However, iPSC-CMs studied to date resemble immature embryonic myocytes and therefore do not adequately recapitulate native adult cardiomyocyte phenotypes. Since extracellular matrix plays an essential role in heart development and maturation in vivo, we sought to develop a synthetic culture matrix that could enhance functional maturation of iPSC-CMs in vitro. In this study, we employed a library of combinatorial polymers comprising of three functional subunits - poly-ε-caprolacton (PCL), polyethylene glycol (PEG), and carboxylated PCL (cPCL) - as synthetic substrates for culturing human iPSC-CMs. Of these, iPSC-CMs cultured on 4%PEG-96%PCL (each % indicates the corresponding molar ratio) exhibit the greatest contractility and mitochondrial function. These functional enhancements are associated with increased expression of cardiac myosin light chain-2v, cardiac troponin I and integrin alpha-7. Importantly, iPSC-CMs cultured on 4%PEG-96%PCL demonstrate troponin I (TnI) isoform switch from the fetal slow skeletal TnI (ssTnI) to the postnatal cardiac TnI (cTnI), the first report of such transition in vitro. Finally, culturing iPSC-CMs on 4%PEG-96%PCL also significantly increased expression of genes encoding intermediate filaments known to transduce integrin-mediated mechanical signals to the myofilaments. In summary, our study demonstrates that synthetic culture matrices engineered from combinatorial polymers can be utilized to promote in vitro maturation of human iPSC-CMs through the engagement of critical matrix-integrin interactions.
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Affiliation(s)
- Young Wook Chun
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Daniel A Balikov
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Tromondae K Feaster
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Charles H Williams
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Calvin C Sheng
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jung-Bok Lee
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Timothy C Boire
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - M Diana Neely
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Leon M Bellan
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA; Department of Mechanical Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Kevin C Ess
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Aaron B Bowman
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Hak-Joon Sung
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA.
| | - Charles C Hong
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Research Medicine, Veterans Affairs TVHS, Nashville, TN 37212, USA.
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25
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Hempel JE, Williams CH, Hong CC. Preface. Chemical biology. Methods Mol Biol 2015; 1263:v. [PMID: 25774396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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26
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Chun YW, Feaster TK, Williams CH, Sheng CC, Frist AY, Su YR, Bichell DP, Hong CC. Abstract 122: A Novel Mutation in a X-linked Gene Causes Human Congenital Dilated Cardiomyopathy. Circ Res 2014. [DOI: 10.1161/res.115.suppl_1.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Congenital dilated cardiomyopathy (cDCM) is a rare but often fatal disease. In most cases, there is no family history, and its etiology is unknown. A major hurdle to elucidating a mechanistic understanding of congenital cardiomyopathy, and primary cardiomyopathies in general, has been a lack of access to diseased human cardiac tissues. Recent advances in patient-derived induced pluripotent stem cells (iPSCs) now enable production of human cardiomyocytes (iPSC-CMs) and allows for a systematic study of normal and diseased cardiomyocytes. We hypothesize that cardiomyocytes generated from iPSCs derived from cDCM patients will exhibit cellular and molecular differences from those generated from healthy donor iPSCs and that a rare genetic mutation, or a collection of mutations, plays a critical role in cDCM pathogenesis. To test these hypotheses, we generated cardiomyocytes from iPSCs derived from a 7-month old male with cDCM using a robust cardiac induction protocol based on the “matrigel sandwich” method of Kamp and colleagues. With this remarkably robust induction method, iPSC-CMs from the cDCM patient and a healthy control donor exhibited proteomic profiles that were 99.7% superimposable. Despite the close similarity at the global proteome level, iPSC-CMs from the cDCM patient showed greatly reduced contractility and dramatic structural defects in the sarcomere and the mitochondria. Finally, bioinformatics analyses of the RNAseq data of the patient’s iPSC-CMs discovered a putative causal mutation in an evolutionarily conserved site in a X-linked gene with unknown function. In summary, our work demonstrates that iPSC-based approaches are particularly useful for the study of human congenital heart diseases. We plan to confirm the causality of this mutation using gene editing techniques such as CRISPR/Cas9 and explore the role of this novel gene in cardiomyocyte structure and function.
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27
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28
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Williams CL, Willard S, Kouba A, Sparks D, Holmes W, Falcone J, Williams CH, Brown A. Dietary shifts affect the gastrointestinal microflora of the giant panda (Ailuropoda melanoleuca). J Anim Physiol Anim Nutr (Berl) 2012; 97:577-85. [PMID: 22524500 DOI: 10.1111/j.1439-0396.2012.01299.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Giant pandas exhibit seasonal changes in bamboo plant part preference. The influences on the gastrointestinal tracts (GIT) microbial populations were evaluated during a 14-month period for a pair of adult male and female giant pandas housed at the Memphis Zoo using traditional culturing methods to enumerate eight bacterial groups (total anaerobes, total aerobes (TAR), streptococci (STR), total enterics, Escherichia coli, Bacteroides spp., lactobacilli and Clostridium spp.). Both the male and female pandas altered bamboo consumption behaviours, with a sharp decrease in leaf preference in April 2010 and returning to high levels of leaf preference from June to October, corresponding to significant shifts in the densities of TAR, STR, and lactobacilli and Bacteroides spp. These findings indicate seasonal changes in food preference affect the assemblages of microbial populations within the GIT of the giant panda and contribute to a better understanding of the importance of bamboo in this species' foraging strategy.
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Affiliation(s)
- C L Williams
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State, MS 39762, USA
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29
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Affiliation(s)
- Zhiyong Cheng
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-5606, USA
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30
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Huang HH, Day L, Cass CL, Ballou DP, Williams CH, Williams DL. Investigations of the catalytic mechanism of thioredoxin glutathione reductase from Schistosoma mansoni. Biochemistry 2011; 50:5870-82. [PMID: 21630672 DOI: 10.1021/bi200107n] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Thioredoxin glutathione reductase from Schistosoma mansoni (SmTGR) catalyzes the reduction of both thioredoxin and glutathione disulfides (GSSG), thus playing a crucial role in maintaining redox homeostasis in the parasite. In line with this role, previous studies have demonstrated that SmTGR is a promising drug target for schistosomiasis. To aid in the development of efficacious drugs that target SmTGR, it is essential to understand the catalytic mechanism of SmTGR. SmTGR is a dimeric flavoprotein in the glutathione reductase family and has a head-to-tail arrangement of its monomers; each subunit has the components of both a thioredoxin reductase (TrxR) domain and a glutaredoxin (Grx) domain. However, the active site of the TrxR domain is composed of residues from both subunits: FAD and a redox-active Cys-154/Cys-159 pair from one subunit and a redox-active Cys-596'/Sec-597' pair from the other; the active site of the Grx domain contains a redox-active Cys-28/Cys-31 pair. Via its Cys-28/Cys-31 dithiol and/or its Cys-596'/Sec-597' thiol-selenolate, SmTGR can catalyze the reduction of a variety of substrates by NADPH. It is presumed that SmTGR catalyzes deglutathionylation reactions via the Cys-28/Cys-31 dithiol. Our anaerobic titration data suggest that reducing equivalents from NADPH can indeed reach the Cys-28/Cys-31 disulfide in the Grx domain to facilitate reductions effected by this cysteine pair. To clarify the specific chemical roles of each redox-active residue with respect to its various reactivities, we generated variants of SmTGR. Cys-28 variants had no Grx deglutathionylation activity, whereas Cys-31 variants retained partial Grx deglutathionylation activity, indicating that the Cys-28 thiolate is the nucleophile initiating deglutathionylation. Lags in the steady-state kinetics, found when wild-type SmTGR was incubated at high concentrations of GSSG, were not present in Grx variants, indicating that this cysteine pair is in some way responsible for the lags. A Sec-597 variant was still able to reduce a variety of substrates, albeit slowly, showing that selenocysteine is important but is not the sole determinant for the broad substrate tolerance of the enzyme. Our data show that Cys-520 and Cys-574 are not likely to be involved in the catalytic mechanism.
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Affiliation(s)
- Hsin-Hung Huang
- Department of Microbiology and Immunology, Rush University Medical Center, Chicago, Illinois 60612, United States
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31
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Abstract
Differentiation of pluripotent stem cells is tightly controlled by temporal and spatial regulation of multiple key signaling pathways. One of the hurdles to its understanding has been the varied methods in correlating changes of key signaling events to differentiation efficiency. We describe here the use of a mouse embryonic stem (ES) cell based assay to identify critical time windows for Wnt/β-catenin and BMP signal activation during cardiogenic induction. By scoring for contracting embryonic bodies (EBs) in a 96-well plate format, we can quickly quantify cardiogenic efficiency and identify crucial time windows for Wnt/β-catenin and BMP signal activation in a time course following specific modulator treatments. The principal outlined here is not limited to cardiac induction alone, and can be applied towards the study of many other cell lineages. In addition, the 96-well format has the potential to be further developed as a high throughput, automated assay to allow for the testing of more sophisticated experimental hypotheses.
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Affiliation(s)
- Ada Ao
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University School of Medicine
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32
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Abstract
Given their small embryo size, rapid development, transparency, fecundity, and numerous molecular, morphological and physiological similarities to mammals, zebrafish has emerged as a powerful in vivo platform for phenotype-based drug screens and chemical genetic analysis. Here, we demonstrate a simple, practical method for large-scale screening of small molecules using zebrafish embryos.
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Affiliation(s)
- Jijun Hao
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University School of Medicine
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33
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Huang HH, Arscott LD, Ballou DP, Williams CH. Function of Glu-469' in the acid-base catalysis of thioredoxin reductase from Drosophila melanogaster. Biochemistry 2009; 47:12769-76. [PMID: 18991392 DOI: 10.1021/bi801449h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Thioredoxin reductase (TrxR) catalyzes the reduction of thioredoxin (Trx) by NADPH. Because dipteran insects such as Drosophila melanogaster lack glutathione reductase, their TrxRs are particularly important for antioxidant protection; reduced Trx reacts nonenzymatically with oxidized glutathione to maintain a high glutathione/glutathione disulfide ratio. Like other members of the pyridine nucleotide-disulfide oxidoreductase family, TrxR is a homodimer; in the enzyme from D. melanogaster (DmTrxR), each catalytically active unit consists of three redox centers: FAD and an N-terminal Cys-57-Cys-62 redox-active disulfide from one monomer and a Cys-489'-Cys-490' C-terminal redox-active disulfide from the second monomer. A dyad of His-464' and Glu-469' in TrxR acts as the acid-base catalyst of the dithiol-disulfide interchange reactions required in catalysis [Huang, H.-H., et al. (2008) Biochemistry 47, 1721-1731]. In this investigation, the role of Glu-469' in catalysis by DmTrxR has been studied. The E469'A and E469'Q DmTrxR variants retain 28 and 35% of the wild-type activity, respectively, indicating that this glutamate residue is important but not critical to catalysis. The pH dependence of V(max) for both glutamate variants yields pK(a) values of 6.0 and 8.7, compared to those in the wild-type enzyme of 6.4 and 9.3, respectively, indicating that the basicity of His-464' in TrxR in complex with its substrate, DmTrx-2, is significantly lower in the glutamate variants than in wild-type enzyme. The rates of some steps in the reductive half-reactions in both glutamate variants are much slower than those of the wild-type enzyme. On the basis of our observations, it is proposed that the function of Glu-469' is to facilitate the positioning of His-464' toward the interchange thiol, Cys-57, as suggested for the analogous residue in glutathione reductase.
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Affiliation(s)
- Hsin-Hung Huang
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0606, USA
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34
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Huang HH, Arscott LD, Ballou DP, Williams CH. Acid−Base Catalysis in the Mechanism of Thioredoxin Reductase from Drosophila melanogaster. Biochemistry 2008; 47:1721-31. [DOI: 10.1021/bi702040u] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hsin-Hung Huang
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0606
| | - L. David Arscott
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0606
| | - David P. Ballou
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0606
| | - Charles H. Williams
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0606
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35
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Cheng Z, Arscott LD, Ballou DP, Williams CH. The relationship of the redox potentials of thioredoxin and thioredoxin reductase from Drosophila melanogaster to the enzymatic mechanism: reduced thioredoxin is the reductant of glutathione in Drosophila. Biochemistry 2007; 46:7875-85. [PMID: 17550271 DOI: 10.1021/bi700442r] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thioredoxin reductase from Drosophila melanogaster (DmTrxR) catalyzes the reversible transfer of reducing equivalents between NADPH and thioredoxin (Trx), a small protein that is involved in a wide variety of biological redox processes. The catalysis involves three essential redox states of the enzyme: the oxidized form of DmTrxR (Eox), the 2-electron-reduced forms (EH2), and the 4-electron-reduced forms (EH4). In the present work, the macroscopic redox potentials of Eox/EH2 and EH2/EH4 couples were determined to be -272 +/- 5 mV for Em(Eox/EH2) and -298 +/- 11 mV for Em(EH2/EH4) on the basis of redox equilibria between DmTrxR and NADH. The value for Em(EH2/EH4) obtained from the steady-state kinetics of the TrxR-catalyzed reaction between NADPH and D. melanogaster Trx-2 (DmTrx-2) was reasonably consistent with that based on redox equilibria. The redox potential of the Trx-(S)2/Trx-(SH)2 couple from D. melanogaster Trx-2 (DmTrx-2) was calculated to be -275.4 +/- 0.3 mV by using the Nernst equation and the Keq for the equilibrium of the reaction involving NADP/NADPH and Trx-(S)2/Trx-(SH)2. For the accurate determination of the Keq, an improved protocol has been developed to minimize errors that can be introduced by using starting concentrations far from equilibrium of the TrxR-catalyzed reaction between NADPH and Trx. This improved approach gives an Em of -284.2 +/- 1.0 mV for Escherichia coli Trx and -271.9 +/- 0.4 mV for Plasmodium falciparum Trx, which agree well with published values (-283 or -285 mV and -270 mV, respectively). The redox potentials determined herein provide further direct evidence for the proposed catalytic mechanism of DmTrxR, and cast new light on the essential role of the DmTrx system in cycling GSSG/GSH and maintaining the intracellular redox homeostasis in D. melanogaster where glutathione reductase is absent.
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Affiliation(s)
- Zhiyong Cheng
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0606, USA
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McMillan PJ, Arscott LD, Ballou DP, Becker K, Williams CH, Müller S. Identification of acid-base catalytic residues of high-Mr thioredoxin reductase from Plasmodium falciparum. J Biol Chem 2006; 281:32967-77. [PMID: 16950793 DOI: 10.1074/jbc.m601141200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
High-M(r) thioredoxin reductase from the malaria parasite Plasmodium falciparum (PfTrxR) contains three redox active centers (FAD, Cys-88/Cys-93, and Cys-535/Cys-540) that are in redox communication. The catalytic mechanism of PfTrxR, which involves dithiol-disulfide interchanges requiring acid-base catalysis, was studied by steady-state kinetics, spectral analyses of anaerobic static titrations, and rapid kinetics analysis of wild-type enzyme and variants involving the His-509-Glu-514 dyad as the presumed acid-base catalyst. The dyad is conserved in all members of the enzyme family. Substitution of His-509 with glutamine and Glu-514 with alanine led to TrxR with only 0.5 and 7% of wild type activity, respectively, thus demonstrating the crucial roles of these residues for enzymatic activity. The H509Q variant had rate constants in both the reductive and oxidative half-reactions that were dramatically less than those of wild-type enzyme, and no thiolateflavin charge-transfer complex was observed. Glu-514 was shown to be involved in dithiol-disulfide interchange between the Cys-88/Cys-93 and Cys-535/Cys-540 pairs. In addition, Glu-514 appears to greatly enhance the role of His-509 in acid-base catalysis. It can be concluded that the His-509-Glu-514 dyad, in analogy to those in related oxidoreductases, acts as the acid-base catalyst in PfTrxR.
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Affiliation(s)
- Paul J McMillan
- Institute of Biomedical and Life Sciences, Infection and Immunity, Wellcome Centre for Molecular Parasitology, University of Glasgow, Glasgow G12 8TA, Scotland, UK
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Johansson L, Arscott LD, Ballou DP, Williams CH, Arnér ESJ. Studies of an active site mutant of the selenoprotein thioredoxin reductase: the Ser-Cys-Cys-Ser motif of the insect orthologue is not sufficient to replace the Cys-Sec dyad in the mammalian enzyme. Free Radic Biol Med 2006; 41:649-56. [PMID: 16863998 DOI: 10.1016/j.freeradbiomed.2006.05.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2006] [Revised: 05/03/2006] [Accepted: 05/04/2006] [Indexed: 11/22/2022]
Abstract
We have mutated the redox active C-terminal motif, Gly-Cys-Sec-Gly, of the mammalian selenoprotein thioredoxin reductase (TrxR) to mimic the C-terminal Ser-Cys-Cys-Ser motif of the non-selenoprotein orthologue of Drosophila melanogaster (DmTrxR). The activity of DmTrxR is almost equal to that of mammalian TrxR, which is surprising, because Cys mutants of selenoproteins are normally 1-2 orders of magnitude less active than their selenocysteine (Sec) containing counterparts. It was shown earlier that the flanking Ser residues were important for activating the Cys residues in DmTrxR (Gromer, et.al. (2003) PNAS 100, 12618-12623). However, the "Drosophila mimic" mutant of the mammalian enzyme studied herein had <0.5% activity compared to wild-type. Rapid kinetic studies revealed that all of the redox centers of the mutant were active, but that the C-terminal dithiols were not effective reductants of thioredoxin. The charge-transfer complex of the two-electron reduced enzyme slowly disappeared as the N-terminal dithiols reduced the C-terminal disulfide. In wild-type enzyme, the selenenylsulfide is more difficult to reduce and the charge-transfer complex is more stable. These findings suggest that features in addition to the flanking Ser residues are important for facilitating the high activity of the insect enzyme and that the corresponding features are absent in mammalian TrxR.
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Affiliation(s)
- Linda Johansson
- Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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Affiliation(s)
- C H Williams
- Departments of Biochemistry and Bacteriology, University of Rochester School of Medicine and Dentistry, Rochester, New York
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Andricopulo AD, Akoachere MB, Krogh R, Nickel C, McLeish MJ, Kenyon GL, Arscott LD, Williams CH, Davioud-Charvet E, Becker K. Specific inhibitors of Plasmodium falciparum thioredoxin reductase as potential antimalarial agents. Bioorg Med Chem Lett 2006; 16:2283-92. [PMID: 16458512 DOI: 10.1016/j.bmcl.2006.01.027] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2005] [Revised: 01/05/2006] [Accepted: 01/06/2006] [Indexed: 11/28/2022]
Abstract
Plasmodium falciparum thioredoxin reductase (PfTrxR: NADPH+Trx(S)2+H+<-->NADP++Trx(SH)2) is a high Mr flavin-dependent TrxR that reduces thioredoxin (Trx) via a CysXXXXCys pair located penultimately to the C-terminal Gly. In this respect, PfTrxR differs significantly from its human counterpart which bears a Cys-Sec redox pair at the same position. PfTrxR is essentially involved in antioxidant defense and redox regulation of the parasite and has been previously validated by knock-out studies as a potential drug target for malaria chemotherapy. Moreover, human TrxR is present in most cancer cells at levels tenfold higher than in normal cells. Here we report the discovery of a series of potent inhibitors of PfTrxR. The three most promising inhibitors, 3(IC50(PfTrxR)=2 microM and IC50(hTrxR)=50 microM), 7(IC50(PfTrxR)=2 microM and IC50(hTrxR)=140 microM), and 11(IC50(PfTrxR)=0.5 microM and IC50(hTrxR)=4 microM) were selective for the parasite enzyme. Detailed mechanistic characterization of the effects of these compounds on the PfTrxR-catalyzed reaction showed clear uncompetitive inhibition with respect to both substrate and cofactor. For the most specific PfTrxR inhibitor 7, an alkylation mechanism study based on a thiol conjugation model was performed. Furthermore, all three compounds were active in the lower micromolar range on the chloroquine-resistant P. falciparum strain K1 in vitro.
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Affiliation(s)
- A D Andricopulo
- College of Pharmacy, University of Michigan, 428 Church Street, Ann Arbor, MI 48109-1065, USA
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40
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Deponte M, Urig S, Arscott LD, Fritz-Wolf K, Réau R, Herold-Mende C, Koncarevic S, Meyer M, Davioud-Charvet E, Ballou DP, Williams CH, Becker K. Mechanistic studies on a novel, highly potent gold-phosphole inhibitor of human glutathione reductase. J Biol Chem 2005; 280:20628-37. [PMID: 15792952 DOI: 10.1074/jbc.m412519200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The homodimeric flavoprotein glutathione reductase (GR) is a central player of cellular redox metabolism, connecting NADPH to the large pool of redox-active thiols. In this work, the inhibition of human GR by a novel gold-phosphole inhibitor (GoPI) has been studied in vitro. Two modes of inhibition are observed, reversible inhibition that is competitive with GSSG followed by irreversible inhibition. When approximately 1 nm GoPI is incubated with NADPH-reduced GR (1.4 nm) the enzyme becomes 50% inhibited. This appears to be the most potent stable inhibitor of human GR to date. Analyzing the monophasic oxidative half-reaction of reduced GR with GSSG at pH 6.9 revealed a K(d)((app)) for GSSG of 63 microm, and a k((obs)max) of 106 s(-1) at 4 degrees C. The reversible inhibition by the gold-phosphole complex [{1-phenyl-2,5-di(2-pyridyl)phosphole}AuCl] involves formation of a complex at the GSSG-binding site of GR (K(d) = 0.46 microm) followed by nucleophilic attack of an active site cysteine residue that leads to covalent modification and complete inactivation of the enzyme. Data from titration spectra, molecular modeling, stopped-flow, and steady-state kinetics support this theory. In addition, covalent binding of the inhibitor to human GR was demonstrated by mass spectrometry. The extraordinary properties of the compound and its derivatives might be exploited for cell biological studies or medical applications, e.g. as an anti-tumor or antiparasitic drug. Preliminary experiments with glioblastoma cells cultured in vitro indicate an anti-proliferative effect of the inhibitor in the lower micromolar range.
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Affiliation(s)
- Marcel Deponte
- Interdisciplinary Research Center, Justus Liebig University, D-35392 Giessen, Germany
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41
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Eisenreich W, Kemter K, Bacher A, Mulrooney SB, Williams CH, Müller F. 13C-, 15N- and 31P-NMR studies of oxidized and reduced low molecular mass thioredoxin reductase and some mutant proteins. ACTA ACUST UNITED AC 2004; 271:1437-52. [PMID: 15066170 DOI: 10.1111/j.1432-1033.2004.04043.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Thioredoxin reductase (TrxR) from Escherichia coli, the mutant proteins E159Y and C138S, and the mutant protein C138S treated with phenylmercuric acetate were reconstituted with [U-(13)C(17),U-(15)N(4)]FAD and analysed, in their oxidized and reduced states, by (13)C-, (15)N- and (31)P-NMR spectroscopy. The enzymes studied showed very similar (31)P-NMR spectra in the oxidized state, consisting of two peaks at -9.8 and -11.5 p.p.m. In the reduced state, the two peaks merge into one apparent peak (at -9.8 p.p.m.). The data are compared with published (31)P-NMR data of enzymes closely related to TrxR. (13)C and (15)N-NMR chemical shifts of TrxR and the mutant proteins in the oxidized state provided information about the electronic structure of the protein-bound cofactor and its interactions with the apoproteins. Strong hydrogen bonds exist between protein-bound flavin and the apoproteins at C(2)O, C(4)O, N(1) and N(5). The N(10) atoms in the enzymes are slightly out of the molecular plane of the flavin. Of the ribityl carbon atoms C(10alpha,gamma,delta) are the most affected upon binding to the apoprotein and the large downfield shift of the C(10gamma) atom indicates strong hydrogen bonding with the apoprotein. The hydrogen bonding pattern observed is in excellent agreement with X-ray data, except for the N(1) and the N(3) atoms where a reversed situation was observed. Some chemical shifts observed in C138S deviate considerably from those of the other enzymes. From this it is concluded that C138S is in the FO conformation and the others are in the FR conformation, supporting published data. In the reduced state, strong hydrogen bonding interactions are observed between C(2)O and C(4)O and the apoprotein. As revealed by the (15)N chemical shifts and the N(5)H coupling constant the N(5) and the N(10) atom are highly sp(3) hybridized. The calculation of the endocyclic angles for the N(5) and the N(10) atoms shows the angles to be approximately 109 degrees, in perfect agreement with X-ray data showing that the flavin assumes a bent conformation along the N(10)/N(5) axis of the flavin. In contrast, the N(1) is highly sp(2) hybridized and is protonated, i.e. in the neutral state. Upon reduction of the enzymes, the (13)C chemical shifts of some atoms of the ribityl side chain undergo considerable changes also indicating conformational rearrangements of the side-chain interactions with the apoproteins. The chemical shifts between native TrxR and C138S are now rather similar and differ from those of the two other mutant proteins. This strongly indicates that the former enzymes are in the FO conformation and the other two are in the FR conformation. The data are discussed briefly in the context of published NMR data obtained with a variety of flavoproteins.
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Affiliation(s)
- Wolfgang Eisenreich
- Lehrstuhl für Organische Chemie und Biochemie, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
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Davioud-Charvet E, McLeish MJ, Veine DM, Giegel D, Arscott LD, Andricopulo AD, Becker K, Müller S, Schirmer RH, Williams CH, Kenyon GL. Mechanism-based inactivation of thioredoxin reductase from Plasmodium falciparum by Mannich bases. Implication for cytotoxicity. Biochemistry 2004; 42:13319-30. [PMID: 14609342 DOI: 10.1021/bi0353629] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thioredoxin reductase (TrxR) is the homodimeric flavoenzyme that catalyzes reduction of thioredoxin disulfide (Trx). For Plasmodium falciparum, a causative agent of tropical malaria, TrxR is an essential protein which has been validated as a drug target. The high-throughput screening of 350000 compounds has identified Mannich bases as a new class of TrxR mechanism-based inhibitors. During catalysis, TrxR conducts reducing equivalents from the NADPH-reduced flavin to Trx via the two redox-active cysteine pairs, Cys88-Cys93 and Cys535'-Cys540', referred to as N-terminal and C-terminal cysteine pairs. The structures of unsaturated Mannich bases suggested that they could act as bisalkylating agents leading to a macrocycle that involves both C-terminal cysteines of TrxR. To confirm this hypothesis, different Mannich bases possessing one or two electrophilic centers were synthesized and first studied in detail using glutathione as a model thiol. Michael addition of glutathione to the double bond of an unsaturated Mannich base (3a) occurs readily at physiological pH. Elimination of the amino group, promoted by base-catalyzed enolization of the ketone, is followed by addition of a second nucleophile. The intermediate formed in this reaction is an alpha,beta-unsaturated ketone that can react rapidly with a second thiol. When studying TrxR as a target of Mannich bases, we took advantage of the fact that the charge-transfer complex formed between the thiolate of Cys88 and the flavin in the reduced enzyme can be observed spectroscopically. The data show that it is the C-terminal Cys 535'-Cys540' pair rather than the N-terminal Cys88-Cys93 pair that is modified by the inhibitor. Although alkylated TrxR is unable to turn over its natural substrate Trx, it can reduce low M(r) electron acceptors such as methyl methanethiolsulfonate by using its unmodified N-terminal thiols. On the basis of results with chemically distinct Mannich bases, a detailed mechanism for the inactivation of TrxR is proposed.
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Gromer S, Johansson L, Bauer H, Arscott LD, Rauch S, Ballou DP, Williams CH, Schirmer RH, Arnér ESJ. Active sites of thioredoxin reductases: why selenoproteins? Proc Natl Acad Sci U S A 2003; 100:12618-23. [PMID: 14569031 PMCID: PMC240667 DOI: 10.1073/pnas.2134510100] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2003] [Indexed: 11/18/2022] Open
Abstract
Selenium, an essential trace element for mammals, is incorporated into a selected class of selenoproteins as selenocysteine. All known isoenzymes of mammalian thioredoxin (Trx) reductases (TrxRs) employ selenium in the C-terminal redox center -Gly-Cys-Sec-Gly-COOH for reduction of Trx and other substrates, whereas the corresponding sequence in Drosophila melanogaster TrxR is -Ser-Cys-Cys-Ser-COOH. Surprisingly, the catalytic competence of these orthologous enzymes is similar, whereas direct Sec-to-Cys substitution of mammalian TrxR, or other selenoenzymes, yields almost inactive enzyme. TrxRs are therefore ideal for studying the biology of selenocysteine by comparative enzymology. Here we show that the serine residues flanking the C-terminal Cys residues of Drosophila TrxRs are responsible for activating the cysteines to match the catalytic efficiency of a selenocysteine-cysteine pair as in mammalian TrxR, obviating the need for selenium. This finding suggests that the occurrence of selenoenzymes, which implies that the organism is selenium-dependent, is not necessarily associated with improved enzyme efficiency. Our data suggest that the selective advantage of selenoenzymes is a broader range of substrates and a broader range of microenvironmental conditions in which enzyme activity is possible.
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Affiliation(s)
- Stephan Gromer
- Biochemie-Zentrum Heidelberg, Heidelberg University, Im Neuenheimer Feld 504, D-69120 Heidelberg, Germany.
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Bauer H, Massey V, Arscott LD, Schirmer RH, Ballou DP, Williams CH. The mechanism of high Mr thioredoxin reductase from Drosophila melanogaster. J Biol Chem 2003; 278:33020-8. [PMID: 12816954 DOI: 10.1074/jbc.m303762200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Drosophila melanogaster thioredoxin reductase-1 (DmTrxR-1) is a key flavoenzyme in dipteran insects, where it substitutes for glutathione reductase. DmTrxR-1 belongs to the family of dimeric, high Mr thioredoxin reductases, which catalyze reduction of thioredoxin by NADPH. Thioredoxin reductase has an N-terminal redox-active disulfide (Cys57-Cys62) adjacent to the flavin and a redox-active C-terminal cysteine pair (Cys489'-Cys490' in the other subunit) that transfer electrons from Cys57-Cys62 to the substrate thioredoxin. Cys489'-Cys490' functions similarly to Cys495-Sec496 (Sec = selenocysteine) and Cys535-XXXX-Cys540 in human and parasite Plasmodium falciparum enzymes, but a catalytic redox center formed by adjacent Cys residues, as observed in DmTrxR-1, is unprecedented. Our data show, for the first time in a high Mr TrxR, that DmTrxR-1 oscillates between the 2-electron reduced state, EH2, and the 4-electron state, EH4, in catalysis, after the initial priming reduction of the oxidized enzyme (Eox) to EH2. The reductive half-reaction consumes 2 eq of NADPH in two observable steps to produce EH4. The first equivalent yields a FADH--NADP+ charge-transfer complex that reduces the adjacent disulfide to form a thiolate-flavin charge-transfer complex. EH4 reacts with thioredoxin rapidly to produce EH2. In contrast, Eox formation is slow and incomplete; thus, EH2 of wild-type cannot reduce thioredoxin at catalytically competent rates. Mutants lacking the C-terminal redox center, C489S, C490S, and C489S/C490S, are incapable of reducing thioredoxin and can only be reduced to EH2 forms. Additional data suggest that Cys57 attacks Cys490' in the interchange reaction between the N-terminal dithiol and the C-terminal disulfide.
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Affiliation(s)
- Holger Bauer
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606, USA
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Abstract
Studies were carried out primarily to assess the role of insulin in regulating iodide uptake in the mammary gland. Using cultured mammary gland explants from virgin and pregnant mice (12-14 days into gestation), insulin (1 microg/ml) was shown to stimulate iodide uptake after a 2-day exposure period. The effect of insulin was manifested by itself, as well as in the presence of cortisol and prolactin. Optimal iodide uptake was observed when tissues were treated with all three lactogenic hormones (insulin, cortisol, and prolactin). In a time-course experiment, the effect of insulin alone was initially observed after a 10-hr treatment; the effect was maintained for 30 hr. In dose-response studies, 1 ng/ml insulin elicited a significant effect after 24 hr in culture; a maximal effect was achieved with 50-100 ng/ml insulin. The optimal cortisol concentration for a maximum stimulation of iodide uptake was 10(-7)M. In a quantitative Western blot analysis employing an antibody to the sodium-iodide symporter, insulin stimulated an upregulation of the transporter protein after a 4-, 8-, or 20-hr treatment with insulin. Perchlorate and thiocyanate abolished the insulin effect on iodide uptake, further suggesting that the insulin response occurs via a stimulation of the sodium-iodide symporter. Clearly, insulin is an important and essential hormone in the lactogenic hormone complex for regulating iodide uptake in the mammary gland, but maximal expression of iodide uptake is only expressed when all three lactogenic hormones are present.
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Affiliation(s)
- James A Rillema
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan 48201-1928, USA.
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47
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Abstract
Disseminated intravascular coagulation (DIC) has been considered a rather rare syndrome characterized by severe bleeding. In fact, both of these beliefs are wrong. Bleeding is fairly rare in DIC. The clotting parameters are usually normal unless the DIC is fulminating. It is usually thought that fibrinogen may be low or absent in DIC. However, afibrinogenemia is rare. Fibrinogen is usually high in DIC because of the high rate of fibrinogen manufacture by the liver in response to stress. DIC is very common and most cases are never diagnosed. This is because it has been hard to find fibrin thrombi in autopsy cases and because acute severe bleeding is uncommon. The reason fibrin thrombi are rare may be because they have been lysed by endogenous fibrinolytic enzymes before the autopsy. The appearance of endogenous fibrinolytic response could be a defense mechanism to lyse the microclots of DIC. In fact, this response is often successful. This defense can be aided by the administration of plasminogen activators that will lyse the clots. Heparin has been used for the treatment of DIC but has proved useless and is, in fact, dangerous. This is because heparin will not dissolve clots and may actually promote platelet agglutination. Administration of plasminogen activators will actually prevent bleeding diathesis.
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Affiliation(s)
- R M Hardaway
- Department of Surgery and Anesthesiology, Texas Tech University Health Science Center, El Paso, Texas 79905, USA.
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van den Berg PA, Mulrooney SB, Gobets B, van Stokkum IH, van Hoek A, Williams CH, Visser AJ. Exploring the conformational equilibrium of E. coli thioredoxin reductase: characterization of two catalytically important states by ultrafast flavin fluorescence spectroscopy. Protein Sci 2001; 10:2037-49. [PMID: 11567095 PMCID: PMC2374229 DOI: 10.1110/ps.06701] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The conformational dynamics of wild-type Escherichia coli thioredoxin reductase (TrxR) and the mutant enzyme C138S were studied by ultrafast time-resolved fluorescence of the flavin cofactor in combination with circular dichroism (both in the flavin fingerprint and far-UV regions) and steady-state fluorescence and absorption spectroscopy. The spectroscopic data show two conformational states of the enzyme (named FO and FR), of which the physical characteristics differ considerably. Ultrafast fluorescence lifetime measurements make it possible to distinguish between the two different populations: Dominant picosecond lifetimes of approximately 1 ps (contribution 75%) and 7 ps (8%) are associated with the FO species in TrxR C138S. Long-lived fluorescence with two time constants in the range of 0.2-1 ns (total contribution 17%) originates from enzyme molecules in the FR conformation. The near absence of fast lifetime components in oxidized wild-type TrxR supports the idea of this enzyme being predominantly in the FR conformation. The emission spectrum of the FO conformation is blue-shifted with respect to that of the FR conformation. Because of the large difference in fluorescence characteristics, fluorescence measurements on time scales longer than 100 ps are fully determined by the fraction of enzyme molecules in the FR conformation. Binding of the thiol reagent phenyl mercuric acetate to wild-type enzyme and TrxR C138S stabilizes the enzymes in the FR conformation. Specific binding of the NADPH-analog, AADP(+), to the FR conformation resulted in dynamic fluorescence quenching in support of the multiple quenching sites model. Raising the temperature from 277K-323K resulted in a moderate shift to the FR conformation for TrxR C138S. High concentrations of the cosolvent glycerol triggered the domain rotation from the FO to the FR conformation.
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Affiliation(s)
- P A van den Berg
- MicroSpectroscopy Centre, Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands
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49
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Hardaway RM, Harke H, Tyroch AH, Williams CH, Vazquez Y, Krause GF. Treatment of severe acute respiratory distress syndrome: a final report on a phase I study. Am Surg 2001; 67:377-82. [PMID: 11308009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Adult respiratory distress syndrome (ARDS) has a high mortality. Its only effective treatment is respiratory therapy. If this fails mortality is probably 100 per cent. No other treatment for ARDS has proved effective including "magic bullets." Twenty patients suffering from ARDS secondary to trauma and/or sepsis failed to respond to treatment with mechanical ventilation and positive end-expiratory pressure. On the assumption that disseminated intravascular coagulation initiates ARDS by occluding the pulmonary microcirculation with microclots, the patients were treated with plasminogen activators. The patients responded with significant improvement in partial pressure of oxygen in arterial blood. No bleeding occurred and clotting parameters remained normal. We conclude that ARDS can be safely treated with plasminogen activator.
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Affiliation(s)
- R M Hardaway
- Department of Surgery, Texas Tech University School of Medicine, El Paso 79902, USA
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50
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Bohme CC, Arscott LD, Becker K, Schirmer RH, Williams CH. Kinetic characterization of glutathione reductase from the malarial parasite Plasmodium falciparum. Comparison with the human enzyme. J Biol Chem 2000; 275:37317-23. [PMID: 10969088 DOI: 10.1074/jbc.m007695200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The homodimeric flavoenzyme glutathione reductase (GR) maintains high intracellular concentrations of the antioxidant glutathione (GSSG + NADPH + H(+) <--> 2 GSH + NADP(+)). Due to its central function in cellular redox metabolism, inhibition of GR from the malarial parasite Plasmodium falciparum represents an important approach to antimalarial drug development; therefore, the catalytic mechanism of GR from P. falciparum has been analyzed and compared with the human host enzyme. The reductive half-reaction is similar to the analogous reaction with GR from other species. The oxidative half-reaction is biphasic, reflecting formation and breakdown of a mixed disulfide between the interchange thiol and GSH. The equilibrium between the E(ox)-EH(2) and GSSG-GSH couples has been modeled showing that the Michaelis complex, mixed disulfide-GSH, is the predominant enzyme form as the oxidative half-reaction progresses; rate constants used in modeling allow calculation of an K(eq) from the Haldane relationship, 0.075, very similar to the K(eq) of the same reaction for the yeast enzyme (0.085) (Arscott, L. D., Veine, D. M., and Williams, C. H., Jr. (2000) Biochemistry 39, 4711-4721). Enzyme-monitored turnover indicates that E(FADH(-))(S-S). NADP(+) and E(FAD)(SH)(2).NADPH are dominant enzyme species in turnover. Since the individual forms of the enzyme differ in their susceptibility to inhibitors, the prevailing states of GR in the cell are of practical relevance.
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Affiliation(s)
- C C Bohme
- Department of Veterans Affairs Medical Center, Ann Arbor, Michigan 48105, Center of Biochemistry, Heidelberg University, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
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