Amplification and propagation of endothelial signaling is likely to be dependent upon the release of local paracrine factors. Reactive oxygen species, including superoxide derived from activated inflammatory cells, activate endothelial cells under inflammatory and ischemia/reperfusion conditions. Subsequently, endothelial damage may potentiate inflammation and ischemic organ injury. Determining a means to reduce endothelial damage is therefore warranted, and may lead to the development of novel therapeutic approaches to treat ischemic and inflammatory diseases. The long-term goal of the proposed research project is to understand the molecular mechanisms of superoxide- mediated endothelial injury. In this proposal, we postulate that superoxide is a signaling molecule that facilitates endoplasmic reticulum Ca2+ signaling and triggers mitochondrial and nuclear stress. The guiding hypothesis is that superoxide raises intracellular Ca2+ and leads to mitochondrial Ca2+ overload, resulting in mitochondrial signaling. Extracellular superoxide selectively induces Ca2+-dependent depolarization independent of other oxidant species. Further, superoxide-evoked signals activate the redox sensitive transcription factor NF-:B. The uncoupling of extracellular superoxide-evoked signal from the mitochondria results in mitochondrial membrane potential preservation and endothelial cell survival.
The specific aims of this project are to examine (Specific Aim 1) how superoxide triggers upstream Ca2+ signaling and selectively activates inositol 1,4,5-trisphosphate receptors (InsP3R) both in vitro and in vivo;(Specific Aim 2) the role of extracellular superoxide-mediated Ca2+ signaling in mitochondrial pathophysiology (mitochondrial redox status-NADH and glutathione levels, mitochondrial ROS generation and mitochondrial membrane potential);(Specific Aim 3) the nuclear events that activate endothelial inflammatory mechanisms by InsP3R-linked ROS signaling. The proposed experiments should provide information on: (A) the involvement of InsP3Rs and their selective role in endothelial Ca2+ signaling during oxidative stress. (B) The relationship between mitochondrial dysfunction and inflammatory signaling in endothelial dysfunction. (C) This result will provide a novel signaling link between inflammatory and endothelial cells under pathophysiological conditions and lead to the development of novel therapeutic targets.

Public Health Relevance

The pulmonary vascular endothelium plays a key role in lung heath by translating blood signals into vascular function. During septic shock, an important and under-recognized signal is leukocyte-derived superoxide, which stimulates pulmonary endothelial cells by mobilizing calcium. Understanding the mechanisms of superoxide-mediated calcium signaling and mitochondria-nuclear stress in endothelial cells are crucial to elucidating the fundamental role of superoxide in both cell survival and death during physiological and pathological processes.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
Project #
Application #
Study Section
Vascular Cell and Molecular Biology Study Section (VCMB)
Program Officer
Charette, Marc F
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Temple University
Schools of Medicine
United States
Zip Code
Alevriadou, B Rita; Shanmughapriya, Santhanam; Patel, Akshar et al. (2017) Mitochondrial Ca2+ transport in the endothelium: regulation by ions, redox signalling and mechanical forces. J R Soc Interface 14:
Gupta, Manish K; Kaminski, Rafal; Mullen, Brian et al. (2017) HIV-1 Nef-induced cardiotoxicity through dysregulation of autophagy. Sci Rep 7:8572
Luongo, Timothy S; Lambert, Jonathan P; Gross, Polina et al. (2017) The mitochondrial Na+/Ca2+ exchanger is essential for Ca2+ homeostasis and viability. Nature 545:93-97
Michael, James V; Wurtzel, Jeremy G T; Mao, Guang Fen et al. (2017) Platelet microparticles infiltrating solid tumors transfer miRNAs that suppress tumor growth. Blood 130:567-580
Joseph, Leroy C; Kokkinaki, Dimitra; Valenti, Mesele-Christina et al. (2017) Inhibition of NADPH oxidase 2 (NOX2) prevents sepsis-induced cardiomyopathy by improving calcium handling and mitochondrial function. JCI Insight 2:
Dong, Zhiwei; Shanmughapriya, Santhanam; Tomar, Dhanendra et al. (2017) Mitochondrial Ca2+ Uniporter Is a Mitochondrial Luminal Redox Sensor that Augments MCU Channel Activity. Mol Cell 65:1014-1028.e7
Bao, Lei; Chen, Shu-Jen; Conrad, Kathleen et al. (2016) Depletion of the Human Ion Channel TRPM2 in Neuroblastoma Demonstrates Its Key Role in Cell Survival through Modulation of Mitochondrial Reactive Oxygen Species and Bioenergetics. J Biol Chem 291:24449-24464
Scheitlin, Christopher G; Julian, Justin A; Shanmughapriya, Santhanam et al. (2016) Endothelial mitochondria regulate the intracellular Ca2+ response to fluid shear stress. Am J Physiol Cell Physiol 310:C479-90
Tomar, Dhanendra; Dong, Zhiwei; Shanmughapriya, Santhanam et al. (2016) MCUR1 Is a Scaffold Factor for the MCU Complex Function and Promotes Mitochondrial Bioenergetics. Cell Rep 15:1673-85
Lee, Samuel K; Shanmughapriya, Santhanam; Mok, Mac C Y et al. (2016) Structural Insights into Mitochondrial Calcium Uniporter Regulation by Divalent Cations. Cell Chem Biol 23:1157-1169

Showing the most recent 10 out of 44 publications