Confocal microscopy of the mitochondrial permeability transition in necrotic and apoptotic cell death

1999 ◽  
Vol 66 ◽  
pp. 205-222 ◽  
Author(s):  
John J. Lemasters ◽  
Ting Qian ◽  
Lawrence C. Trost ◽  
Brian Herman ◽  
Wayne E. Cascio ◽  
...  
Keyword(s):  
Cell Death ◽  
Confocal Microscopy ◽  
Cyclosporin A ◽  
Cell Injury ◽  
Mitochondrial Permeability Transition ◽  
Apoptotic Cell ◽  
Permeability Transition ◽  
Matrix Space ◽  
Necrosis Factor Alpha ◽  
Mitochondrial Permeability

Opening of a high-conductance pore in the mitochondrial inner membrane induces onset of the mitochondrial permeability transition (mPT). Cyclosporin A and trifluoperazine inhibit this pore and block necrotic cell death in oxidative stress, Ca2+ ionophore toxicity, Reye-related drug toxicity, pH-dependent ischaemia/reperfusion injury and other models of cell injury. Confocal fluorescence microscopy directly visualizes the increased mitochondrial membrane permeability of the mPT from the movement of calcein from the cytosol into the matrix space. Pyridine nucleotide oxidation, increased mitochondrial Ca2+ and mitochondrial generation of reactive oxygen species (ROS) all contribute to the onset of the mPT in situ. Confocal microscopy also shows directly that the mPT is a critical link in apoptotic signalling by tumour necrosis factor-alpha at a point downstream of caspase 8 and upstream of caspase 3. Cyclosporin A blocks this mPT, preventing release of pro-apoptotic cytochrome c from mitochondria and subsequent apoptotic cell killing. Progression to necrosis or apoptosis after the mPT depends on the availability of ATP, which blocks necrosis but promotes the apoptotic programme. Given the pathophysiological importance of the mPT, development of agents to modulate the mPT represents an important new goal for pharmaceutical drug discovery.

Quenching or Misalignment? Confocal Microscopy Onset of the Mitochondrial Permeability Transition in Cultured Hepatocytes

1999 ◽  
Vol 5 (S2) ◽  
pp. 468-469
Author(s):  
Ting Qian ◽  
Lawrence C. Trost ◽  
John J. Lemasters
Keyword(s):  
Confocal Microscopy ◽  
Mitochondrial Permeability Transition ◽  
Apoptotic Cell ◽  
Negative Contrast ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Dark Spot ◽  
Cultured Hepatocytes ◽  
Mitochondrial Permeability ◽  
Calcein Am

INTRODUCTION: The mitochondrial permeability transition (MPT) has been implicated in mediating both necrotic and apoptotic cell death. Opening of the permeability transition pore in the mitochondrial inner membrane causes the MPT. Previously, our laboratory developed a method to detect the MPT in cultured hepatocytes by visualizing redistribution of calcein fluorescence from the cytosol into the mitochondria after permeability transition pore opening, using confocal microscopy. (1). However, a recent paper suggests that unstained mitochondria are unlikely to be detected against bright cytosolic signal, because fluorescence spreading magnifies the size of emitting objects while reducing that of dark spot (2). Rather, it was suggested that dark mitochondrial voids in green calcein images were the result of fluorescent quenching by concurrent use of a red-fluorescing mitochondrial dye, tetramethylrhodamine (TMRM). The AIMS of the present study were to determine 1) whether small voids can be visualized in the absence of any potential quenching agent; 2) whether quenching can produce dark mitochondrial voids and 3) the importance of alignment in visualizing mitochondria as negative contrast by confocal microscopy. METHODS: Overnight cultured rat hepatocytes were used. To load calcein exclusively into cytosolic space, hepatocytes were incubated with 1 μM calcein AM for 15 min at 37°C. To load calcein into both cytosol and mitochondria, cells were incubated with 1 μM calcein AM for 1 hour at 4°C.

scholarly journals The Mitochondrial Permeability Transition Is Required for Tumor Necrosis Factor Alpha-Mediated Apoptosis and Cytochrome c Release

1998 ◽  
Vol 18 (11) ◽  
pp. 6353-6364 ◽  
Author(s):  
Cynthia A. Bradham ◽  
Ting Qian ◽  
Konrad Streetz ◽  
Christian Trautwein ◽  
David A. Brenner ◽  
...  
Keyword(s):  
Cell Death ◽  
Tumor Necrosis ◽  
Caspase 3 ◽  
Mitochondrial Permeability Transition ◽  
Permeability Transition ◽  
Necrosis Factor Alpha ◽  
Mitochondrial Permeability ◽  
Factor Alpha ◽  
Induced Apoptosis ◽  
Necrosis Factor

ABSTRACT This study assesses the controversial role of the mitochondrial permeability transition (MPT) in apoptosis. In primary rat hepatocytes expressing an IκB superrepressor, tumor necrosis factor alpha (TNFα) induced apoptosis as shown by nuclear morphology, DNA ladder formation, and caspase 3 activation. Confocal microscopy showed that TNFα induced onset of the MPT and mitochondrial depolarization beginning 9 h after TNFα treatment. Initially, depolarization and the MPT occurred in only a subset of mitochondria; however, by 12 h after TNFα treatment, virtually all mitochondria were affected. Cyclosporin A (CsA), an inhibitor of the MPT, blocked TNFα-mediated apoptosis and cytochrome c release. Caspase 3 activation, cytochrome c release, and apoptotic nuclear morphological changes were induced after onset of the MPT and were prevented by CsA. Depolarization and onset of the MPT were blocked in hepatocytes expressing ΔFADD, a dominant negative mutant of Fas-associated protein with death domain (FADD), or crmA, a natural serpin inhibitor of caspases. In contrast, Asp-Glu-Val-Asp-cho, an inhibitor of caspase 3, did not block depolarization or onset of the MPT induced by TNFα, although it inhibited cell death completely. In conclusion, the MPT is an essential component in the signaling pathway for TNFα-induced apoptosis in hepatocytes which is required for both cytochrome c release and cell death and functions downstream of FADD and crmA but upstream of caspase 3.

Cyclophilin D-dependent mitochondrial permeability transition regulates some necrotic but not apoptotic cell death

Nature ◽  
2005 ◽  
Vol 434 (7033) ◽  
pp. 652-658 ◽  
Author(s):  
Takashi Nakagawa ◽  
Shigeomi Shimizu ◽  
Tetsuya Watanabe ◽  
Osamu Yamaguchi ◽  
Kinya Otsu ◽  
...  
Keyword(s):  
Cell Death ◽  
Mitochondrial Permeability Transition ◽  
Apoptotic Cell ◽  
Permeability Transition ◽  
Apoptotic Cell Death ◽  
Cyclophilin D ◽  
Mitochondrial Permeability

The mitochondrial permeability transition: its molecular mechanism and role in reperfusion injury

1999 ◽  
Vol 66 ◽  
pp. 181-203 ◽  
Author(s):  
Andrew P. Halestrap
Keyword(s):  
Oxidative Stress ◽  
Cyclosporin A ◽  
Reperfusion Injury ◽  
Molecular Mechanism ◽  
Mitochondrial Permeability Transition ◽  
Adenine Nucleotide ◽  
Apoptotic Cell ◽  
Heart Function ◽  
Permeability Transition ◽  
Mitochondrial Permeability

The mitochondrial permeability transition (mPT) involves the opening of a non-specific pore in the inner membrane of mitochondria, converting them from organelles whose production of ATP sustains the cell, to instruments of death. Here, I first summarize the evidence in favour of our model for the molecular mechanism of the mPT. It is proposed that the adenine nucleotide translocase (ANT) is converted into a non-specific pore through a calcium-mediated conformational change. This requires the binding of a unique cyclophilin (cyclophilin-D, CyP-D) to the ANT, except when matrix [Ca2+] is very high. Binding of CyP-D is increased in response to oxidative stress and some thiol reagents which sensitize the mPT to [Ca2+]. Matrix adenine nucleotides decrease the sensitivity of the mPT to [Ca2+] by binding to the ANT. This is antagonized by carboxyatractyloside (an inhibitor of the ANT) and by modification of specific thiol groups on the ANT by oxidative stress or thiol reagents; such treatments thus enhance the mPT. In contrast, decreasing intracellular pH below 7.0 greatly desensitizes the mPT to [Ca2+]. Conditions which sensitize the mPT towards [Ca2+] are found in hearts reperfused after a period of ischaemia, a process that may irreversibly damage the heart (reperfusion injury). We have demonstrated directly that mPT pores open during reperfusion (but not ischaemia) using a technique that involves entrapment of [3H]deoxyglucose in mitochondria that have undergone the mPT. The mPT may subsequently reverse in hearts that recover from ischaemia/reperfusion, the extent of resealing correlating with recovery of heart function. A variety of agents that antagonize the mPT protect the heart from reperfusion injury, including cyclosporin A, pyruvate and propofol. Mitochondria that undergo the mPT and then reseal may cause cytochrome c release and thus initiate apoptosis in cells subjected to stresses less severe than those causing necrosis. An example is the apoptotic cell death in the hippocampus that occurs several days after insulin-induced hypoglycaemia, and can be prevented by prior treatment with cyclosporin A.

Characterization of Mitochondrial Function During Cell Injury

2001 ◽  
Vol 7 (S2) ◽  
pp. 602-603
Author(s):  
Anna-Liisa Nieminen
Keyword(s):  
Cell Death ◽  
Confocal Microscopy ◽  
Laser Scanning ◽  
Cell Injury ◽  
Mitochondrial Permeability Transition ◽  
Single Cells ◽  
Permeability Transition ◽  
Living Cells ◽  
Cultured Hepatocytes ◽  
Sequence Of Events

Mitochondria play an important role in apoptotic and necrotic cell death. Depending on the stimulus, a variety of mitochondrial dysfunctions can trigger onset of cell death. Assessment of mitochondrial dysfunction in living cells in situis important to understand the sequence of events producing cell injury and death. Laser scanning confocal microscopy, a technique that creates submicron thin optical slices through living cells and tissues, allows us to monitor several mitochondrial events simultaneously in intact single cells over time.During oxidative stress, we monitored mitochondrial redox status, Ca2+ increase, reactive oxygen species (ROS), the mitochondrial permeability transition, and mitochondrial depolarization in cultured hepatocytes. When an oxidant chemical, t-BuOOH, was added to cultured hepatocytes, oxidation of mitochondrial pyridine nucleotides occurred as visualized directly by ultraviolet confocal microscopy of NAD(P)H autofluorescence. This event was followed by an increase of mitochondrial Ca2+ measured by the Ca2+-indicating fluorophore, Rhod-2.

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