News Article | November 17, 2016
(Philadelphia, PA) - The inability of cells to eliminate damaged proteins and organelles following the blockage of a coronary artery and its subsequent re-opening with angioplasty or medications - a sequence known as ischemia/reperfusion - often results in irreparable damage to the heart muscle. To date, attempts to prevent this damage in humans have been unsuccessful. According to a new study by scientists at the Lewis Katz School of Medicine at Temple University (LKSOM), however, it may be possible to substantially limit reperfusion injury by increasing the expression of a protein known as Bcl-2-associated athanogene 3 (BAG3). "We found that BAG3 plays a pivotal role in protecting the heart from damage caused by reperfusion injury," explained the study's lead author, Feifei Su, MD, PhD, a postdoctoral fellow in the laboratory of Arthur M. Feldman, MD, PhD, Professor of Medicine at LKSOM. Ischemia impairs the function of cellular organelles including mitochondria, the cell's energy-producers, resulting in harmful effects that set the stage for a sudden burst in the generation of toxic oxidizing substances when oxygenated blood reenters the heart. The toxins lead to fundamental changes in the biology of the heart. Notably, they activate cell death pathways and decrease autophagy - the process by which cells remove malfunctioning proteins and organelles. Autophagy plays a critical role in removing damaged myocardial cells (the muscular tissue of the heart) and misfolded heart muscle fibers. The new work shows that BAG3 expression both inactivates cell death pathways, helping prevent the loss of heart cells triggered by ischemia, and activates autophagy, thereby enabling cells to clear out impaired components of the heart cell before they inflict extensive damage. The findings, published online November 17 in the journal JCI Insight, open the door to the investigation of BAG3 as a therapeutic target during reperfusion in heart attack patients. In initial work, the research group found that BAG3 promotes autophagy and inhibits programmed cell death (apoptosis) in cultured cardiac myocytes. Subsequently, they found that when heart cells were exposed to the stress of hypoxia/reoxygenation or when living mice were stressed with ischemia/reperfusion, they suffered dramatic reductions in BAG3 expression. Those paradoxical changes in BAG3 levels turned out to be directly associated with increases in biomarkers of autophagy and with decreases in biomarkers of apoptosis. By artificially knocking down BAG3 in mouse heart cells, the researchers were able to produce an apoptosis-autophagy biomarker phenotype nearly identical to that produced by hypoxia/reoxygenation. By contrast, BAG3 overexpression normalized apoptosis and autophagy. In a key experiment, the Temple team further showed that tissue damage sustained following ischemia/reperfusion could be substantially reduced by treating mice with BAG3 prior to vessel re-opening. BAG3 overexpression before the onset of ischemia/reperfusion also resulted in normalization in apoptosis and autophagy biomarkers. According to Dr. Feldman, the senior investigator on the project, his team's interest in the role of BAG3 in the heart has grown in recent years, owing to their discovery of a unique BAG3 mutation in a family with familial dilated cardiomyopathy, a genetic condition characterized by the development of heart failure between early and late adulthood. "After finding that a mutation in BAG3 caused heart failure in a Philadelphia family, we have been trying to figure out what the protein does in the heart," Dr. Feldman said. "Now that we have a better understanding of its role and what happens when its levels are increased, we can investigate the possibility of targeting BAG3 in human patients using gene therapy or a small molecule." Other researchers on the new study include Feifei Su in the Department of Medicine at LKSOM, Temple University, and the Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, China; Valerie D. Myers in the Department of Medicine at LKSOM, Temple University; Tijana Knezevic, Farzaneh G. Tahrir, Manish K. Gupta, Jennifer Gordon, and Kamel Khalili in the Department of Neuroscience at LKSOM, Temple University; JuFang Wang, Ehre Gao, Muniswamy Madesh, Joseph Rabinowitz, Douglas G. Tilley, and Joseph Y. Cheung in the Center for Translational Medicine at LKSOM, Temple University; and Frederick V. Ramsey in the Department of Clinical Sciences at LKSOM, Temple University. The research was supported by National Institutes of Health grants P01 HL 091799-01 and R01 HL123093. Temple University Health System (TUHS) is a $1.6 billion academic health system dedicated to providing access to quality patient care and supporting excellence in medical education and research. The Health System consists of Temple University Hospital (TUH), ranked among the "Best Hospitals" in the region by U.S. News & World Report; TUH-Episcopal Campus; TUH-Northeastern Campus; Fox Chase Cancer Center, an NCI-designated comprehensive cancer center; Jeanes Hospital, a community-based hospital offering medical, surgical and emergency services; Temple Transport Team, a ground and air-ambulance company; and Temple Physicians, Inc., a network of community-based specialty and primary-care physician practices. TUHS is affiliated with the Lewis Katz School of Medicine at Temple University. The Lewis Katz School of Medicine (LKSOM), established in 1901, is one of the nation's leading medical schools. Each year, the School of Medicine educates approximately 840 medical students and 140 graduate students. Based on its level of funding from the National Institutes of Health, the Katz School of Medicine is the second-highest ranked medical school in Philadelphia and the third-highest in the Commonwealth of Pennsylvania. According to U.S. News & World Report, LKSOM is among the top 10 most applied-to medical schools in the nation. Temple Health refers to the health, education and research activities carried out by the affiliates of Temple University Health System (TUHS) and by the Katz School of Medicine. TUHS neither provides nor controls the provision of health care. All health care is provided by its member organizations or independent health care providers affiliated with TUHS member organizations. Each TUHS member organization is owned and operated pursuant to its governing documents.
News Article | March 2, 2017
(Philadelphia, PA) - Mitochondria - the energy-generating powerhouses of cells - are also a site for oxidative stress and cellular calcium regulation. The latter two functions have long been suspected of being linked mechanistically, and now new research at the Lewis Katz School of Medicine at Temple University (LKSOM) shows precisely how, with the common connection centering on a protein complex known as the mitochondrial Ca2+ uniporter (MCU). "MCU had been known for its part in driving mitochondrial calcium uptake for cellular energy production, which protects cells from bioenergetic crisis, and for its role in eliciting calcium overload-induced cell death," explained senior investigator on the study, Muniswamy Madesh, PhD, Professor in the Department of Medical Genetics and Molecular Biochemistry and Center for Translational Medicine at LKSOM. "Now, we show that MCU has a functional role in both calcium regulation and the sensing of levels of reactive oxygen species (ROS) within mitochondria." The study, published online March 2 in the journal Molecular Cell, is the first to identify a direct role for MCU in mitochondrial ROS-sensing. In previous work, Dr. Madesh and colleagues were the first to show how the MCU protein complex comes together to effect mitochondrial calcium uptake. "We know from that work, and from existing work in the field, that as calcium accumulates in mitochondria, the organelles generate increasing amounts of ROS," Dr. Madesh said. "Mitochondria have a way of dealing with that ROS surge, and because of the relationship between mitochondrial calcium uptake and ROS production, we suspected ROS-targeting of MCU was involved in that process." In the new study, Dr. Madesh and colleagues employed advanced biochemical, cell biological, and superresolution imaging to examine MCU oxidation in the mitochondrion. Critically, they discovered that MCU contains several cysteine molecules in its amino acid structure, only one of which, Cys-97, is capable of undergoing an oxidation-induced reaction known as S-glutathionylation. Structural analyses showed that oxidation-induced S-glutathionylation of Cys-97 triggers conformational changes within MCU. Those changes in turn regulate MCU activity during inflammation, hypoxia, and cardiac stimulation. They also appear to be relevant to cell survival - elimination of ROS-sensing via Cys-97 mutation resulted in persistent MCU channel activity and an increased rate of calcium-uptake, with cells eventually dying from calcium overload. Importantly, Dr. Madesh and colleagues found that S-glutathionylation of Cys-97 is reversible. "Reversible oxidation is essential to the regulation of protein function," Dr. Madesh explained. When switched on by oxidation, Cys-97 augments MCU channel activity that perpetuates cell death. Oxidation reverses when the threat has subsided. The findings could have implications for the understanding of metabolic disorders and neurological and cardiovascular diseases. "Abnormalities in ion homeostasis are a central feature of metabolic disease," Dr. Madesh said. "We plan next to explore the functional significance of ROS and MCU activity in a mouse model using genome editing technology, which should help us answer fundamental questions about MCU's biological functions in mitochondrial ROS-sensing." Other researchers involved in the study include Zhiwei Dong, Santhanam Shanmughapriya, Dhanendra Tomar, Neeharika Nemani, Sarah L. Breves, Aparna Tripathi, Palaniappan Palaniappan, Massimo F. Riitano, Alison Worth, Ajay Seelam, Edmund Carvalho, Ramasamy Subbiah, Fabia?n Jan?a, and Sudarsan Rajan, Department of Medical Genetics and Molecular Biochemistry and the Center for Translational Medicine at LKSOM; Jonathan Soboloff, Department of Medical Genetics and Molecular Biochemistry at LKSOM; Xueqian Zhang and Joseph Y. Cheung, Center for Translational Medicine at LKSOM; Naveed Siddiqui and Peter B. Stathopulos, Department of Physiology and Pharmacology, Western University, London, Ontario, Canada; Solomon Lynch and Jeffrey Caplan, Department of Biological Sciences, Delaware Biotechnology Institute, University of Delaware; Suresh K. Joseph, MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia; Yizhi Peng and Zhiwei Dong, Institute of Burn Research, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China. The research was supported in part by National Institutes of Health grants R01GM109882, R01HL086699, R01HL119306, 1S10RR027327, P01 DA037830, and RO1DK103558. Temple University Health System (TUHS) is a $1.6 billion academic health system dedicated to providing access to quality patient care and supporting excellence in medical education and research. The Health System consists of Temple University Hospital (TUH), ranked among the "Best Hospitals" in the region by U.S. News & World Report; TUH-Episcopal Campus; TUH-Northeastern Campus; Fox Chase Cancer Center, an NCI-designated comprehensive cancer center; Jeanes Hospital, a community-based hospital offering medical, surgical and emergency services; Temple Transport Team, a ground and air-ambulance company; and Temple Physicians, Inc., a network of community-based specialty and primary-care physician practices. TUHS is affiliated with the Lewis Katz School of Medicine at Temple University. The Lewis Katz School of Medicine (LKSOM), established in 1901, is one of the nation's leading medical schools. Each year, the School of Medicine educates approximately 840 medical students and 140 graduate students. Based on its level of funding from the National Institutes of Health, the Katz School of Medicine is the second-highest ranked medical school in Philadelphia and the third-highest in the Commonwealth of Pennsylvania. According to U.S. News & World Report, LKSOM is among the top 10 most applied-to medical schools in the nation. Temple Health refers to the health, education and research activities carried out by the affiliates of Temple University Health System (TUHS) and by the Katz School of Medicine. TUHS neither provides nor controls the provision of health care. All health care is provided by its member organizations or independent health care providers affiliated with TUHS member organizations. Each TUHS member organization is owned and operated pursuant to its governing documents.
Sen A.,Center for Translational Medicine |
Most P.,Center for Translational Medicine |
Most P.,University of Heidelberg |
Peppel K.,Center for Translational Medicine
FEBS Letters | Year: 2014
Exposure to pro-inflammatory cytokines, such as Angiotensin II, endothelin-1 or TNF leads to endothelial dysfunction, characterized by the reduced production of nitric oxide via endothelial nitric oxide synthase (eNOS). We recently identified the Ca2+ binding protein S100A1 as an essential factor required for eNOS activity. Here we report that pro-inflammatory cytokines down-regulate expression of S100A1 in primary human microvascular endothelial cells (HMVECs) via induction of microRNA-138 (miR-138), in a manner that depends on the stabilization of HIF1-α. We show that loss of S100A1 in ECs reduces stimulus-induced NO production, which can be prevented by inhibition of miR-138. Our study suggests that targeting miR-138 might be beneficial for the treatment of cardiovascular disease. © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
Wang W.,University of Washington |
Gong G.,University of Washington |
Wang X.,Institute of Molecular Medicine |
Wei-Lapierre L.,University of Rochester |
And 3 more authors.
Antioxidants and Redox Signaling | Year: 2016
Significance: Recent breakthroughs in mitochondrial research have advanced, reshaped, and revolutionized our view of the role of mitochondria in health and disease. These discoveries include the development of novel tools to probe mitochondrial biology, the molecular identification of mitochondrial functional proteins, and the emergence of new concepts and mechanisms in mitochondrial function regulation. The discovery of "mitochondrial flash" activity has provided unique insights not only into real-time visualization of individual mitochondrial redox and pH dynamics in live cells but has also advanced understanding of the excitability, autonomy, and integration of mitochondrial function in vivo. Recent Advances: The mitochondrial flash is a transient and stochastic event confined within an individual mitochondrion and is observed in a wide range of organisms from plants to Caenorhabditis elegans to mammals. As flash events involve multiple transient concurrent changes within the mitochondrion (e.g., superoxide, pH, and membrane potential), a number of different mitochondrial targeted fluorescent indicators can detect flash activity. Accumulating evidence indicates that flash events reflect integrated snapshots of an intermittent mitochondrial process arising from mitochondrial respiration chain activity associated with the transient opening of the mitochondrial permeability transition pore. Critical Issues: We review the history of flash discovery, summarize current understanding of flash biology, highlight controversies regarding the relative roles of superoxide and pH signals during a flash event, and bring forth the integration of both signals in flash genesis. Future Directions: Investigations using flash as a biomarker and establishing its role in cell signaling pathway will move the field forward. Antioxid. Redox Signal. 25, 534-549. © Wang Wang et al.
Pleger S.T.,University of Heidelberg |
Brinks H.,University of Bern |
Ritterhoff J.,University of Heidelberg |
Raake P.,University of Heidelberg |
And 4 more authors.
Circulation Research | Year: 2013
Gene therapy, aimed at the correction of key pathologies being out of reach for conventional drugs, bears the potential to alter the treatment of cardiovascular diseases radically and thereby of heart failure. Heart failure gene therapy refers to a therapeutic system of targeted drug delivery to the heart that uses formulations of DNA and RNA, whose products determine the therapeutic classification through their biological actions. Among resident cardiac cells, cardiomyocytes have been the therapeutic target of numerous attempts to regenerate systolic and diastolic performance, to reverse remodeling and restore electric stability and metabolism. Although the concept to intervene directly within the genetic and molecular foundation of cardiac cells is simple and elegant, the path to clinical reality has been arduous because of the challenge on delivery technologies and vectors, expression regulation, and complex mechanisms of action of therapeutic gene products. Nonetheless, since the first demonstration of in vivo gene transfer into myocardium, there have been a series of advancements that have driven the evolution of heart failure gene therapy from an experimental tool to the threshold of becoming a viable clinical option. The objective of this review is to discuss the current state of the art in the field and point out inevitable innovations on which the future evolution of heart failure gene therapy into an effective and safe clinical treatment relies. © 2013 American Heart Association, Inc.
Di Benedetto A.,University of Washington |
Watkins M.,University of Washington |
Grimston S.,University of Washington |
Salazar V.,University of Washington |
And 5 more authors.
Journal of Cell Science | Year: 2010
We have previously shown that targeted expression of a dominant-negative truncated form of N-cadherin (Cdh2) delays acquisition of peak bone mass in mice and retards osteoblast differentiation; whereas deletion of cadherin 11 (Cdh11), another osteoblast cadherin, leads to only modest osteopenia. To determine the specific roles of these two cadherins in the adult skeleton, we generated mice with an osteoblast/osteocyte specific Cdh2 ablation (cKO) and double Cdh2+/-;Cdh11-/- germline mutant mice. Age-dependent osteopenia and smaller diaphyses with decreased bone strength characterize cKO bones. By contrast, Cdh2+/-;Cdh11-/- exhibit severely reduced trabecular bone mass, decreased in vivo bone formation rate, smaller diaphyses and impaired bone strength relative to single Cdh11 null mice. The number of bone marrow immature precursors and osteoprogenitor cells is reduced in both cKO and Cdh2+/-;Cdh11-/- mice, suggesting that N-cadherin is involved in maintenance of the stromal cell precursor pool via the osteoblast. Although Cdh11 is dispensable for postnatal skeletal growth, it favors osteogenesis over adipogenesis. Deletion of either cadherin reduces β-catenin abundance and β-catenin-dependent gene expression, whereas N-cadherin loss disrupts cell-cell adhesion more severely than loss of cadherin 11. Thus, Cdh2 and Cdh11 are crucial regulators of postnatal skeletal growth and bone mass maintenance, serving overlapping, yet distinct, functions in the osteogenic lineage.
Radice G.L.,Center for Translational Medicine
Progress in Molecular Biology and Translational Science | Year: 2013
Of the 20 classical cadherin subtypes identified in mammals, the functions of the two initially identified family members E- (epithelial) and N- (neural) cadherin have been most extensively studied. E- and N-Cadherin have mostly mutually exclusive expression patterns, with E-cadherin expressed primarily in epithelial cells, whereas N-cadherin is found in a variety of cells, including neural, muscle, and mesenchymal cells. N-Cadherin function, in particular, appears to be cell context-dependent, as it can mediate strong cell-cell adhesion in the heart but induces changes in cell behavior in favor of a migratory phenotype in the context of epithelial-mesenchymal transition (EMT). The ability of tumor cells to alter their cadherin expression profile, for example, E- to N-cadherin, is critical for malignant progression. Recent advances in mouse molecular genetics, and specifically tissue-specific knockout and knockin alleles of N-cadherin, have provided some unexpected results. This chapter highlights some of the genetic studies that explored the complex role of N-cadherin in embryonic development and disease. © 2013 Elsevier Inc.
Li J.,Center for Translational Medicine |
Radice G.L.,Center for Translational Medicine
Dermatology Research and Practice | Year: 2010
Adherens junctions and desmosomes are intercellular adhesive junctions and essential for the morphogenesis, differentiation, and maintenance of tissues that are subjected to high mechanical stress, including heart and skin. The different junction complexes are organized at the termini of the cardiomyocyte called the intercalated disc. Disruption of adhesive integrity via mutations in genes encoding desmosomal proteins causes an inherited heart disease, arrhythmogenic right ventricular cardiomyopathy (ARVC). Besides plakoglobin, which is shared by adherens junctions and desmosomes, other desmosomal components, desmoglein-2, desmocollin-2, plakophilin-2, and desmoplakin are also present in ultrastructurally defined fascia adherens junctions of heart muscle, but not other tissues. This mixed-type of junctional structure is termed hybrid adhering junction or area composita. Desmosomal plakophilin-2 directly interacts with adherens junction protein alphaT-catenin, providing a new molecular link between the cadherin-catenin complex and desmosome. The area composita only exists in the cardiac intercalated disc of mammalian species suggesting that it evolved to strengthen mechanical coupling in the heart of higher vertebrates. The cross-talk among different junctions and their implication in the pathogenesis of ARVC are discussed in this review. Copyright © 2010 J. Li and G. L. Radice.
Swope D.,Center for Translational Medicine |
Li J.,Center for Translational Medicine |
Radice G.L.,Center for Translational Medicine
Cellular Signalling | Year: 2013
Plakoglobin (PG, γ-Catenin, JUP), a member of the armadillo protein family and close homolog of β-catenin, functions to link cell surface cadherin molecules with the cytoskeleton. PG is the only junctional component found in both desmosomes and adherens junctions and thus plays a critical role in the regulation of cell-cell adhesion. Similar to β-catenin, PG is able to interact with components of the Wnt signaling pathway and directly affect gene expression by binding with LEF/TCF transcription factors. In addition, it has been proposed that PG functions primarily as a competitive inhibitor of β-catenin transcriptional activity by sequestering LEF/TCF. Compared to β-catenin, the contribution of PG as a transcriptional regulator in either physiological or pathological conditions is poorly understood. There is increasing clinical interest in PG as both a structural protein as well as a signaling molecule as mutations have been identified in the human PG gene that cause Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) and cutaneous syndromes. This review will discuss the connection between altered cell adhesion and gene expression and its contribution to disease pathogenesis. © 2012 Elsevier Inc.
Hamad E.,Center for Translational Medicine |
Feldman A.M.,Center for Translational Medicine
Heart Failure Clinics | Year: 2010
Pharmacogenomics is a growing field of research that focuses on how an individual's genetic background influences his or her response to therapy with a drug or device. Increasing evidence from clinical trials in patients with heart failure (HF) due to systolic dysfunction suggests that genetic variations can predict the occurrence of HF, influence the effects of standard therapies, and influence outcomes of HF patients. This article reviews the underlying principles of pharmacogenomics, discusses some of the complex variables that influence the investigational approach to pharmacogenomics, demonstrates how variations in genes encoding a variety of different proteins can influence the effects of pharmacologic agents, and describes the potential impact of pharmacogenomics on the treatment of patients with HF. © 2010 Elsevier Inc. All rights reserved.