Table 1.
Overview on the reported evidences for an involvement of UCP2 and UCP3 in mitochondrial Ca2+ uniport [8]
| Model* | Overexpression | siRNA | UCP2−/− mouse (liver) |
|---|---|---|---|
| Basal mitochondrial Ca2+ | Unchanged | Unchanged | n.d. |
| Mitochondrial Ca2+ uptake | Increased (even under de-polarized conditions) | Strongly reduced (rescue by UCP2 in UCP3 cells treated with siRNA against UCP3) | Absent (no ruthenium red-sensitive Ca2+ entry) |
| Capacity of the MCU | Increased (even under depolarized conditions) | Strongly reduced | Reduced |
| Ca2+ sensitivity of MCU | Unchanged | n.d. | n.d. |
| Basal Δψmito | Unchanged | Unchanged | Unchanged |
| Δψmito upon stimulation/Ca2+ exposure | Unchanged | Unchanged | Unchanged |
| Basal pHmito | Unchanged | Unchanged | n.d. |
| pHmito upon stimulation | Decreased due to elevated [Ca2+]mito | Unchanged | n.d. |
| Basal ATP levels | Unchanged | n.d. | n.d. |
| ATP synthesis | Increased | n.d. | n.d. |
| Basal cytosolic Ca2+ concentration | Unchanged | Unchanged | n.d. |
| Intracellular Ca2+ mobilization | Unchanged | Unchanged | n.d. |
| Mitochondrial structure | Unchanged | Unchanged | n.d. |
| Focal contacts with the ER | Unchanged | Unchanged | n.d. |
| ER Ca2+ content | Unchanged | Unchanged | n.d. |
*
Most experiments were performed in human endothelial cells but were verified in HeLa, Hek293 and CHO cells.