scholarly journals Targeted disruption of PDE3B, but not PDE3A, protects murine heart from ischemia/reperfusion injury

2015 ◽  
Vol 112 (17) ◽  
pp. E2253-E2262 ◽  
Author(s):  
Youn Wook Chung ◽  
Claudia Lagranha ◽  
Yong Chen ◽  
Junhui Sun ◽  
Guang Tong ◽  
...  
Keyword(s):  
Connexin 43 ◽  
Mitochondrial Permeability Transition ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Mouse Heart ◽  
Targeted Disruption

Although inhibition of cyclic nucleotide phosphodiesterase type 3 (PDE3) has been reported to protect rodent heart against ischemia/reperfusion (I/R) injury, neither the specific PDE3 isoform involved nor the underlying mechanisms have been identified. Targeted disruption of PDE3 subfamily B (PDE3B), but not of PDE3 subfamily A (PDE3A), protected mouse heart from I/R injury in vivo and in vitro, with reduced infarct size and improved cardiac function. The cardioprotective effect in PDE3B−/− heart was reversed by blocking cAMP-dependent PKA and by paxilline, an inhibitor of mitochondrial calcium-activated K channels, the opening of which is potentiated by cAMP/PKA signaling. Compared with WT mitochondria, PDE3B−/− mitochondria were enriched in antiapoptotic Bcl-2, produced less reactive oxygen species, and more frequently contacted transverse tubules where PDE3B was localized with caveolin-3. Moreover, a PDE3B−/− mitochondrial fraction containing connexin-43 and caveolin-3 was more resistant to Ca2+-induced opening of the mitochondrial permeability transition pore. Proteomics analyses indicated that PDE3B−/− heart mitochondria fractions were enriched in buoyant ischemia-induced caveolin-3–enriched fractions (ICEFs) containing cardioprotective proteins. Accumulation of proteins into ICEFs was PKA dependent and was achieved by ischemic preconditioning or treatment of WT heart with the PDE3 inhibitor cilostamide. Taken together, these findings indicate that PDE3B deletion confers cardioprotective effects because of cAMP/PKA-induced preconditioning, which is associated with the accumulation of proteins with cardioprotective function in ICEFs. To our knowledge, our study is the first to define a role for PDE3B in cardioprotection against I/R injury and suggests PDE3B as a target for cardiovascular therapies.

scholarly journals Acute Induction of Translocon-Mediated Ca2+ Leak Protects Cardiomyocytes Against Ischemia/Reperfusion Injury

Cells ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1319
Author(s):  
Ribal Al-Mawla ◽  
Mallory Ducrozet ◽  
Nolwenn Tessier ◽  
Lucille Païta ◽  
Bruno Pillot ◽  
...  
Keyword(s):  
Mitochondrial Permeability Transition ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
New Paradigm ◽  
Leak Channel

During myocardial infarction, dysregulation of Ca2+ homeostasis between the reticulum, mitochondria, and cytosol occurs in cardiomyocytes and leads to cell death. Ca2+ leak channels are thought to be key regulators of the reticular Ca2+ homeostasis and cell survival. The present study aimed to determine whether a particular reticular Ca2+ leak channel, the translocon, also known as translocation channel, could be a relevant target against ischemia/reperfusion-mediated heart injury. To achieve this objective, we first used an intramyocardial adenoviral strategy to express biosensors in order to assess Ca2+ variations in freshly isolated adult mouse cardiomyocytes to show that translocon is a functional reticular Ca2+ leak channel. Interestingly, translocon activation by puromycin mobilized a ryanodine receptor (RyR)-independent reticular Ca2+ pool and did not affect the excitation–concentration coupling. Second, puromycin pretreatment decreased mitochondrial Ca2+ content and slowed down the mitochondrial permeability transition pore (mPTP) opening and the rate of cytosolic Ca2+ increase during hypoxia. Finally, this translocon pre-activation also protected cardiomyocytes after in vitro hypoxia reoxygenation and reduced infarct size in mice submitted to in vivo ischemia-reperfusion. Altogether, our report emphasizes the role of translocon in cardioprotection and highlights a new paradigm in cardioprotection by functionally uncoupling the RyR-dependent Ca2+ stores and translocon-dependent Ca2+ stores.

scholarly journals Critical Roles of Calpastatin in Ischemia/Reperfusion Injury in Aged Livers

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1863
Author(s):  
Joseph Flores-Toro ◽  
Sung-Kook Chun ◽  
Jun-Kyu Shin ◽  
Joan Campbell ◽  
Melissa Lichtenberger ◽  
...  
Keyword(s):  
Cell Death ◽  
Mitochondrial Permeability Transition ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Age Groups ◽  
Permeability Transition ◽  
Mitochondrial Morphology ◽  
Human And Mouse

Ischemia/reperfusion (I/R) injury unavoidably occurs during hepatic resection and transplantation. Aged livers poorly tolerate I/R during surgical treatment. Although livers have a powerful endogenous inhibitor of calpains, calpastatin (CAST), I/R activates calpains, leading to impaired autophagy, mitochondrial dysfunction, and hepatocyte death. It is unknown how I/R in aged livers affects CAST. Human and mouse liver biopsies at different ages were collected during in vivo I/R. Hepatocytes were isolated from 3-month- (young) and 26-month-old (aged) mice, and challenged with short in vitro simulated I/R. Cell death, protein expression, autophagy, and mitochondrial permeability transition (MPT) between the two age groups were compared. Adenoviral vector was used to overexpress CAST. Significant cell death was observed only in reperfused aged hepatocytes. Before the commencement of ischemia, CAST expression in aged human and mouse livers and mouse hepatocytes was markedly greater than that in young counterparts. However, reperfusion substantially decreased CAST in aged human and mouse livers. In hepatocytes, reperfusion rapidly depleted aged cells of CAST, cleaved autophagy-related protein 5 (ATG5), and induced defective autophagy and MPT onset, all of which were blocked by CAST overexpression. Furthermore, mitochondrial morphology was shifted toward an elongated shape with CAST overexpression. In conclusion, CAST in aged livers is intrinsically short-lived and lost after short I/R. CAST depletion contributes to age-dependent liver injury after I/R.

scholarly journals The cyclophilin inhibitor NIM-811 increases muscle cell survival with hypoxia in vitro and improves gait performance following ischemia–reperfusion in vivo

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Khairat Bahgat Youssef El Baradie ◽  
Mohammad B. Khan ◽  
Bharati Mendhe ◽  
Jennifer Waller ◽  
Frederick O’Brien ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cell Survival ◽  
Reperfusion Injury ◽  
Mitochondrial Permeability Transition ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Permeability Transition ◽  
Mitochondrial Permeability

AbstractAcute ischemia–reperfusion injury in skeletal muscle is a significant clinical concern in the trauma setting. The mitochondrial permeability transition inhibitor NIM-811 has previously been shown to reduce ischemic injury in the liver and kidney. The effects of this treatment on skeletal muscle are, however, not well understood. We first used an in vitro model of muscle cell ischemia in which primary human skeletal myoblasts were exposed to hypoxic conditions (1% O2 and 5% CO2) for 6 h. Cells were treated with NIM-811 (0–20 µM). MTS assay was used to quantify cell survival and LDH assay to quantify cytotoxicity 2 h after treatment. Results indicate that NIM-811 treatment of ischemic myotubes significantly increased cell survival and decreased LDH in a dose-dependent manner. We then examined NIM-811 effects in vivo using orthodontic rubber bands (ORBs) for 90 min of single hindlimb ischemia. Mice received vehicle or NIM-811 (10 mg/kg BW) 10 min before reperfusion and 3 h later. Ischemia and reperfusion were monitored using laser speckle imaging. In vivo data demonstrate that mice treated with NIM-811 showed increased gait speed and improved Tarlov scores compared to vehicle-treated mice. The ischemic limbs of female mice treated with NIM-811 showed significantly lower levels of MCP-1, IL-23, IL-6, and IL-1α compared to limbs of vehicle-treated mice. Similarly, male mice treated with NIM-811 showed significantly lower levels of MCP-1 and IL-1a. These findings are clinically relevant as MCP-1, IL-23, IL-6, and IL-1α are all pro-inflammatory factors that are thought to contribute directly to tissue damage after ischemic injury. Results from the in vitro and in vivo experiments suggest that NIM-811 and possibly other mitochondrial permeability transition inhibitors may be effective for improving skeletal muscle salvage and survival after ischemia–reperfusion injury.

Abstract 17188: Cryoem Analysis in Cardiac Isolated Mitochondria Reveals New Insights for CsA and mPTP Activation

Circulation ◽  
2018 ◽  
Vol 138 (Suppl_1) ◽  
Author(s):  
Jasiel O Strubbe ◽  
Jason Schrad ◽  
James F Conway ◽  
Kristin N Parent ◽  
Jason N Bazil
Keyword(s):  
Time Course ◽  
Mitochondrial Permeability Transition ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Myocardial Necrosis ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Granule Formation ◽  
Membrane Rupture ◽  
Mptp Opening

Excessive Ca 2+ accumulation is the main source of cardiac tissue and cell death during myocardial ischemia-reperfusion injury (IR injury) and myocardial infarction. Calcium dysregulation and overload leads to mitochondrial dysfunction, excessive reactive oxygen species (ROS) production, catastrophic energy failure, and opening of the cyclosporine A-sensitive mitochondrial permeability transition pore (mPTP). Mitochondrial Ca 2+ accumulation also results in the formation of amorphous Ca 2+ -phosphate granules localized in the mitochondrial matrix. These amorphous electron-dense granules are main components of the mitochondrial Ca 2+ sequestration and buffering system by mechanisms not yet well understood. The two aims of the present study are to test the relationship of Ca 2+ -phosphate granule size and number in cardiac mitochondria 1) exposed to a bolus calcium sufficient to elicit permeabilization and 2) whether CsA-treated mitochondria alters granule formation and size. A time course series of CryoEM images was analyzed to follow the permeabilization process. CryoEM results showed that mitochondrial incubated for longer time-courses have increased number of small granules (40 - 110 nm), swelling, membrane rupture and induction of mPTP opening. Conversely, shorter incubation time resulted in less granules per mitochondrion yet of similar size (35 - 90 nm). CsA- treated mitochondria, on the other hand, showed bigger phosphate granules (120 - 160 nm), and both lower granules per mitochondria and mPTP opening susceptibility. These results suggest a novel mechanism for CsA in which Ca 2+ -phosphate granule sizes are enhanced while maintaining fewer per mitochondrion. This effect may explain why CsA-treated mitochondria have higher calcium tolerance, delayed Ca 2+ -dependent opening of the mPTP, and protects against reperfusion-induced myocardial necrosis.

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