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.
Jiang X.,Institute of Burn Research |
Zhang J.,Institute of Burn Research |
Huang Y.,Institute of Burn Research
Cell Adhesion and Migration | Year: 2015
Tetraspanins are a superfamily of small transmembrane proteins that are expressed in almost all eukaryotic cells. Through interacting with one another and with other membrane and intracellular proteins, tetraspanins regulate a wide range of proteins such as integrins, cell surface receptors, and signaling molecules, and thereby engage in diverse cellular processes ranging from cell adhesion and migration to proliferation and differentiation. In particular, tetraspanins modulate the function of proteins involved in all determining factors of cell migration including cell–cell adhesion, cell–ECM adhesion, cytoskeletal protrusion/contraction, and proteolytic ECM remodeling. We herein provide a brief overview of collective in vitro and in vivo studies of tetraspanins to illustrate their regulatory functions in the migration and trafficking of cancer cells, vascular endothelial cells, skin cells (keratinocytes and fibroblasts), and leukocytes. We also discuss the involvement of tetraspanins in various pathologic and remedial processes that rely on cell migration and their potential value as targets for therapeutic intervention. © 2015 Taylor & Francis Group, LLC.
Luo Y.-Q.,CAEP - China Academy of Engineering Physics |
Huang L.-X.,CAEP - China Academy of Engineering Physics |
Yang J.-J.,Institute of Burn Research |
Shen Z.-X.,CAEP - China Academy of Engineering Physics |
And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012
Thermal injuries are a serious medical problem in the China. The accurate determination of burn degree is difficult for scatheless diagnose and a precondition of treating burn wounds. Multi-spectral photographic analysis is expected to play an important role in determining burn wound degree, the Liquid Crystal Tunable Filter has a capability of selecting the observing wavelength instaneously with high spectral resolution and excellent imaging quality in visible and near-infrared spectrum band. Taking advantage of this filter, we have developed a LCTF imaging spectrometer prototype instrument at visible wavelength bands for burn wound diagnose. In this paper, spectral analysis experiments were first performed on KUNMING mice and burn injury patients to find the characteristic reflective spectral curves at 400nm-1800nm, the imaging spectrometer prototype instrument using LCTFs which are sensitive to radiation in 420nm-750nmwavelength bands was built based on spectral analysis results. The spectral imaging experiments on burn injury patients have verified the excellent properties of the prototype instrument, including high quality spectral images with spectral resolution of less than 7nm and continuous selection of the output wavelength. The burn areas of patients were marked with different colors which represents as different burn degree and the spectral imaging system has thus been proven to have the ability to classify the burn areas through comparing their reflective spectral curves with characteristic spectrum of the different burn degree in spectral database in the future. Finally, the application of the LCTF imaging spectrometer to burn wound diagnose are summarized based on the results of spectral imaging experiments on burn injuries. © 2012 SPIE.