POS-073 Rapid Changes in the Mitochondrial Membrane Potential of Proximal Tubular Cells At the Start of Ischemia/Reperfusion Injury

Cathepsin D is one of the major lysosomal aspartic proteases that is essential for the normal functioning of the autophagy-lysosomal system. In the kidney, cathepsin D is enriched in renal proximal tubular epithelial cells, and its levels increase during acute kidney injury. To investigate how cathepsin D-deficiency impacts renal proximal tubular cells, we employed a conditional knockout CtsDflox/−; Spink3Cre mouse. Immunohistochemical analyses using anti-cathepsin D antibody revealed that cathepsin D was significantly decreased in tubular epithelial cells of the cortico-medullary region, mainly in renal proximal tubular cells of this mouse. Cathepsin D-deficient renal proximal tubular cells showed an increase of microtubule-associated protein light chain 3 (LC3; a marker for autophagosome/autolysosome)-signals and an accumulation of abnormal autophagic structures. Renal ischemia/reperfusion injury resulted in an increase of early kidney injury marker, Kidney injury molecule 1 (Kim-1), in the cathepsin D-deficient renal tubular epithelial cells of the CtsDflox/−; Spink3Cre mouse. Inflammation marker was also increased in the cortico-medullary region of the CtsDflox/−; Spink3Cre mouse. Our results indicated that lack of cathepsin D in the renal tubular epithelial cells led to an increase of sensitivity against ischemia/reperfusion injury.

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Restored microRNA-326-5p Inhibits Neuronal Apoptosis and Attenuates Mitochondrial Damage via Suppressing STAT3 in Cerebral Ischemia/Reperfusion Injury

Nanoscale Research Letters ◽

10.1186/s11671-021-03520-3 ◽

2021 ◽

Vol 16 (1) ◽

Author(s):

Yumin Huang ◽

Yingge Wang ◽

Zuowei Duan ◽

Jingyan Liang ◽

Yijun Xu ◽

...

Keyword(s):

Oxidative Stress ◽

Membrane Potential ◽

Mitochondrial Membrane Potential ◽

Mitochondrial Membrane ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Pathological Changes ◽

Cerebral Ischemia Reperfusion ◽

Cerebral Ischemia Reperfusion Injury ◽

Brain Tissues

AbstractStudies have greatly explored the role of microRNAs (miRNAs) in cerebral ischemia/reperfusion injury (CI/RI). But the specific mechanism of miR-326-5p in CI/RI is still elusive. Hence, this study was to unmask the mechanism of miR-326-5p/signal transducer and activator of transcription-3 (STAT3) axis in CI/RI. Two models (oxygen and glucose deprivation [OGD] in primary rat cortical neurons and middle cerebral artery occlusion [MCAO] in Sprague–Dawley rats) were established to mimic CI/RI in vitro and in vivo, respectively. Loss- and gain-of function assays were performed with OGD-treated neurons and with MCAO rats. Afterward, viability, apoptosis, oxidative stress and mitochondrial membrane potential in OGD-treated neurons were tested, as well as pathological changes, apoptosis and mitochondrial membrane potential in brain tissues of MCAO rats. Mitofusin-2 (Mfn2), miR-326-5p and STAT3 expression in OGD-treated neurons and in brain tissues of MCAO rats were detected. Mfn2 and miR-326-5p were reduced, and STAT3 was elevated in OGD-treated neurons and brain tissues of MCAO rats. miR-326-5p targeted and negatively regulated STAT3 expression. Restoring miR-326-5p or reducing STAT3 reinforced viability, inhibited apoptosis and oxidative stress, increased mitochondrial membrane potential and increased Mfn2 expression in OGD-treated neurons. Up-regulating miR-326-5p or down-regulating STAT3 relieved pathological changes, inhibited apoptosis and elevated mitochondrial membrane potential and Mfn2 expression in brain tissues of rats with MCAO. This study elucidates that up-regulated miR-326-5p or down-regulated STAT3 protects against CI/RI by elevating Mfn2 expression.

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Molecular Mechanisms of Ischemia–Reperfusion Injury in Brain: Pivotal Role of the Mitochondrial Membrane Potential in Reactive Oxygen Species Generation

Molecular Neurobiology ◽

10.1007/s12035-012-8344-z ◽

2012 ◽

Vol 47 (1) ◽

pp. 9-23 ◽

Cited By ~ 326

Author(s):

Thomas H. Sanderson ◽

Christian A. Reynolds ◽

Rita Kumar ◽

Karin Przyklenk ◽

Maik Hüttemann

Keyword(s):

Reactive Oxygen Species ◽

Membrane Potential ◽

Reperfusion Injury ◽

Mitochondrial Membrane ◽

Molecular Mechanisms ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Reactive Oxygen Species Generation ◽

Oxygen Species

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Mitochondrial membrane potential modulates regulation of mitochondrial Ca2+ in rat ventricular myocytes

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00589.2004 ◽

2005 ◽

Vol 288 (4) ◽

pp. H1820-H1828 ◽

Cited By ~ 56

Author(s):

Masao Saotome ◽

Hideki Katoh ◽

Hiroshi Satoh ◽

Shiro Nagasaka ◽

Shu Yoshihara ◽

...

Keyword(s):

Membrane Potential ◽

Mitochondrial Membrane Potential ◽

Mitochondrial Membrane ◽

Mitochondrial Permeability Transition ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Control Level ◽

Permeability Transition ◽

Activity Levels ◽

Physiological Range

Although recent studies focused on the contribution of mitochondrial Ca2+ to the mechanisms of ischemia-reperfusion injury, the regulation of mitochondrial Ca2+ under pathophysiological conditions remains largely unclear. By using saponin-permeabilized rat myocytes, we measured mitochondrial membrane potential (ΔΨm) and mitochondrial Ca2+ concentration ([Ca2+]m) at the physiological range of cytosolic Ca2+ concentration ([Ca2+]c; 300 nM) and investigated the regulation of [Ca2+]m during both normal and dissipated ΔΨm. When ΔΨm was partially depolarized by carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP, 0.01–0.1 μM), there were dose-dependent decreases in [Ca2+]m. When complete ΔΨm dissipation was achieved by FCCP (0.3–1 μM), [Ca2+]m remained at one-half of the control level despite no Ca2+ influx via the Ca2+ uniporter. The ΔΨm dissipation by FCCP accelerated calcein leakage from mitochondria in a cyclosporin A (CsA)-sensitive manner, which indicates that ΔΨm dissipation opened the mitochondrial permeability transition pore (mPTP). After FCCP addition, inhibition of the mPTP by CsA caused further [Ca2+]m reduction; however, inhibition of mitochondrial Na+/Ca2+ exchange (mitoNCX) by a Na+-free solution abolished this [Ca2+]m reduction. Cytosolic Na+ concentrations that yielded one-half maximal activity levels for mitoNCX were 3.6 mM at normal ΔΨm and 7.6 mM at ΔΨm dissipation. We conclude that 1) the mitochondrial Ca2+ uniporter accumulates Ca2+ in a manner that is dependent on ΔΨm at the physiological range of [Ca2+]c; 2) ΔΨm dissipation opens the mPTP and results in Ca2+ influx to mitochondria; and 3) although mitoNCX activity is impaired, mitoNCX extrudes Ca2+ from the matrix even after ΔΨm dissipation.

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