Maintaining mitochondrial function is critical for everyday operation of the heart. Proper mitochondrial function requires maintaining regulated and selective permeability of the mitochondrial inner membrane to ions and metabolites. Mitochondrial permeability transition occurs when the inner membrane loses its selective permeability by opening of a large-conductance nonselective channel, the permeability transition pore (PTP). High concentrations of mitochondrial Ca2+ and reactive oxygen species (ROS) are known to open PTP. PTP opening depolarizes mitochondria and causes mitochondrial swelling; thus, sustained opening of PTP leads to mitochondrial dysfunction and cell death, which is associated with many cardiovascular diseases including ischemia-reperfusion (I-R) injury and heart failure. Therefore, understanding how PTP is regulated has significant clinical value. It has long been known that increasing mitochondrial Ca2+ concentration opens PTP. More recently, mitochondrial dynamics mediated by fission and fusion have also been suggested to be involved in regulating PTP. However, the mechanisms by which Ca2+ and mitochondrial dynamics regulate PTP remain unknown. Our new findings show that increasing mitochondrial Ca2+ induces phosphorylation of cyclophilin D (CypD) through GSK-3? activation in mitochondria. Furthermore, we have found a transient opening of PTP (tPTP) that is distinct from conventional PTP and is regulated by mitochondrial dynamics proteins. Inhibition of the fission protein Drp1 increases this novel tPTP. Importantly, the inner membrane fusion protein OPA1 was found to be a critical factor for the novel tPTP. Although Drp1 inhibition is known to decrease pathologic PTP opening and reduce myocardial infarction in I-R, the mechanism of this fission inhibition-mediated protection is unknown. We postulate that the mitochondrial dynamics-mediated novel tPTP is a structurally distinct entity from conventional PTP, and thus in pathological conditions, can serve as a relief valve for excess matrix Ca2+ and proton gradient that induces ROS overproduction; as such, it could thereby prevent pathologic opening of PTP. Supported by our findings, the Central Hypothesis is that CypD phosphorylation induced by matrix Ca2+ is a key event for PTP opening, while mitochondrial dynamics regulates novel tPTP, and their interplay determines cardiac pathology outcomes. We will test this hypothesis by three specific aims: (1) to determine the mechanism of Ca2+-induced PTP opening, (2) to determine the mechanism of mitochondrial dynamics-regulated novel tPTP opening, and (3) to investigate the interplay between conventional PTP and novel tPTP in the pathological setting. The proposed studies will utilize advanced in vitro and in vivo cell and molecular biological approaches along with new fluorescence-based assays. Completion of the proposed studies will generate a new paradigm for the regulatory mechanisms of different forms of PTP and their functional interplay. The new findings will provide mechanistic basis for a new therapeutic strategy to decrease heart I-R injury and other cardiac pathology associated with PTP.

Public Health Relevance

Opening of mitochondrial permeability transition pore plays a central role in pathological outcomes in heart attack and other cardiovascular disorders. This proposal intends to determine the new mechanisms of how the permeability transition pore is regulated through calcium and mitochondrial dynamics. The findings from the proposed studies will provide novel insight for developing new therapeutic strategy to ameliorate cardiac ischemia-reperfusion injury and other cardiac pathology.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
Project #
Application #
Study Section
Cardiac Contractility, Hypertrophy, and Failure Study Section (CCHF)
Program Officer
Wong, Renee P
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Thomas Jefferson University
Internal Medicine/Medicine
Schools of Medicine
United States
Zip Code
De La Fuente, Sergio; Lambert, Jonathan P; Nichtova, Zuzana et al. (2018) Spatial Separation of Mitochondrial Calcium Uptake and Extrusion for Energy-Efficient Mitochondrial Calcium Signaling in the Heart. Cell Rep 24:3099-3107.e4
Wang, Wang; Fernandez-Sanz, Celia; Sheu, Shey-Shing (2018) Regulation of mitochondrial bioenergetics by the non-canonical roles of mitochondrial dynamics proteins in the heart. Biochim Biophys Acta Mol Basis Dis 1864:1991-2001
Hurst, Stephen; Hoek, Jan; Sheu, Shey-Shing (2017) Mitochondrial Ca2+ and regulation of the permeability transition pore. J Bioenerg Biomembr 49:27-47
Zhang, Huiliang; Wang, Pei; Bisetto, Sara et al. (2017) A novel fission-independent role of dynamin-related protein 1 in cardiac mitochondrial respiration. Cardiovasc Res 113:160-170
Mishra, Jyotsna; Jhun, Bong Sook; Hurst, Stephen et al. (2017) The Mitochondrial Ca2+Uniporter: Structure, Function, and Pharmacology. Handb Exp Pharmacol 240:129-156
Jhun, Bong Sook; Mishra, Jyotsna; Monaco, Sarah et al. (2016) The mitochondrial Ca2+ uniporter: regulation by auxiliary subunits and signal transduction pathways. Am J Physiol Cell Physiol 311:C67-80
Wang, Wang; Gong, Guohua; Wang, Xianhua et al. (2016) Mitochondrial Flash: Integrative Reactive Oxygen Species and pH Signals in Cell and Organelle Biology. Antioxid Redox Signal 25:534-49
O-Uchi, Jin; Sorenson, Jaime; Jhun, Bong Sook et al. (2015) Isoform-specific dynamic translocation of PKC by ?1-adrenoceptor stimulation in live cells. Biochem Biophys Res Commun 465:464-70
Fujiwara, Keigi; Sheu, Shey-Shing (2015) Mitochondrial dynamics regulate neointima formation. Cardiovasc Res 106:175-7
Gomez, L; Thiebaut, P-A; Paillard, M et al. (2015) The SR/ER-mitochondria calcium crosstalk is regulated by GSK3? during reperfusion injury. Cell Death Differ 22:1890

Showing the most recent 10 out of 26 publications