Single-channel biophysical properties of the left ventricular mitochondrial calcium uniporter complex - 18/05/21
Résumé |
Introduction |
Mitochondrial calcium uniporter (MCU) forms a macromolecular complex composed by MCU, MICU1, MICU2, EMRE and MCUb, which confers its tissue specificity. However, the native single-channel properties and its regulation by kaempferol, a polyphenol known to enhance mitochondrial Ca2+ uptake has never been investigated in left ventricles.
Objective |
Here, we aimed to characterize the single-channel properties of mouse left ventricular MCU complex incorporated in planar lipid bilayer (PLB) and its regulation by kaempferol.
Method |
MCU was purified from mouse left ventricle isolated mitochondria, treated with proteinase K and digitonin to disrupt the outer mitochondrial membrane. Submitochondrial particles were subjected to BN-Page to verify the macromolecular complex integrity. MCU was then incorporated in PLB for electrophysiological recording. Voltage steps were applied from −60mV to +60mV and Ca2+ concentration was increased from 1μM to 1mM at −40mV. Currents were recorded in presence of kaempferol (10μM) and ruthenium red was used to inhibit the single-channel activity.
Results |
At 1μM Ca2+, MCU displayed 4 opening states with a single-channel open probability (Po) of 0.10±0.05 and a single-channel conductance of 0.07±0.01nS. In presence of kaempferol, MCU Po and conductance were slightly increased (0.18±0.08 and 0.10±0.02nS, respectively) and the number of opening states remained unchanged. At 100μM Ca2+, the Po (0.06±0.004) and conductance (0.05±0.01) were not significantly different from those with low Ca2+ condition whereas the single-channel current displayed only the first two opening states. Kaempferol increased both the conductance (0.11±0.02nS) and Po (0.27±0.10) and maintained the MCU in 4 opening states.
Conclusion |
To conclude, we recorded for the first time MCU single-channel isolated from mouse ventricle and demonstrated that Ca2+ impacts the channel opening states while kaempferol increases Po and conductance in presence of high Ca2+.
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Vol 13 - N° 2
P. 229-230 - mai 2021 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.