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Multi-parameter Measurement of the Permeability Transition Pore Opening in Isolated Mouse Heart Mitochondria
Published on: September 7, 2012
Mitochondrial membrane permeabilization produced by PTP, Bax and apoptosis: a 1H-NMR relaxation study
D Pouliquen1, G Bellot, G Guihard
1Inserm UMR 601, Equipe 4, Institut de Biologie, 9 Quai Moncousu, 44035 Nantes cédex, France. daniel.pouliquen@univ-nantes.fr
Abstract:
To analyze the involvement of structured water (bound to macromolecules) in apoptosis-induced mitochondrial outer-membrane permeability, we compared the dynamics of water protons from nuclear magnetic resonance (NMR) data in apoptotic liver mitochondria with that of control mitochondria incubated in vitro with free Ca(2+) (opening of the permeability transition pore, PTP) or with Bax alpha. Our results demonstrate that water molecules in apoptotic mitochondria exhibit an accelerated translational motion of structured water common with that induced by the opening of the PTP, but limited in amplitude. On the other hand, no significant quantitative change in structured water was observed in apoptotic mitochondria, a phenomenon also observed with Bax alpha-induced permeability. We conclude that the changes observed in the different water phases differ both quantitatively and qualitatively during the opening of the PTP and the Bax alpha-induced permeability, and that the apoptotic mitochondria exhibit mixed properties between these model situations.
Insights
Structured water dynamics in liver mitochondria during apoptosis were analyzed using nuclear magnetic resonance (NMR). Apoptotic mitochondria showed altered structured water motion, differing from permeability transition pore opening and Bax alpha-induced permeability.
Area of Science:
- Mitochondrial Biology
- Apoptosis Research
- Biophysics
Background:
- Mitochondrial outer membrane permeabilization is a critical event in apoptosis.
- The role of structured water in regulating mitochondrial membrane permeability is not fully understood.
- Nuclear magnetic resonance (NMR) can probe water dynamics within cellular structures.
Purpose of the Study:
- To investigate the involvement of structured water in apoptosis-induced mitochondrial outer membrane permeability.
- To compare water proton dynamics in apoptotic mitochondria with those induced by permeability transition pore (PTP) opening or Bax alpha.
- To elucidate the quantitative and qualitative differences in water phase changes during different permeability events.
Main Methods:
- Collected nuclear magnetic resonance (NMR) data to analyze water proton dynamics.
- Compared liver mitochondria from apoptotic and control samples.
- Incubated control mitochondria in vitro with free Ca(2+) (to induce PTP opening) or Bax alpha.
Main Results:
- Apoptotic mitochondria exhibited accelerated translational motion of structured water, similar to PTP opening but with limited amplitude.
- No significant quantitative change in structured water was observed in apoptotic mitochondria, mirroring observations with Bax alpha-induced permeability.
- Water molecule dynamics differed quantitatively and qualitatively between PTP opening and Bax alpha-induced permeability.
Conclusions:
- Apoptotic mitochondria display a mixed profile of structured water dynamics, combining features of both PTP opening and Bax alpha-induced permeability.
- The observed changes in structured water phases are distinct for PTP opening and Bax alpha-induced permeability.
- Structured water dynamics provide insights into the complex mechanisms of mitochondrial outer membrane permeabilization during apoptosis.
