Promyelocytic leukemia protein (PML) knockout increases mitochondrial Ca2+ uptake in HeLa cells

• Published in: Biochemical and biophysical research communications 2024-12, Vol.739, p.150990, Article 150990
• Main Authors: Sharipov, R.R., Surin, A.M., Silonov, S.A., Smirnov, E.Y., Neklesova, M.V., Vishnyakov, I.E., Gavrilova, A.A., Mikryukova, A.A., Moskovtsev, A.A., Bakaeva, Z.V., Kolesnikov, S.S., Kuznetsova, I.M., Turoverov, K.K., Fonin, A.V.
• Format: Article
• Language: English
• Subjects: Endoplasmic reticulum; Fluorescence microscopy; Intracellular calcium; Mitochondria; Mitochondria-associated membranes (MAMs)
• ISSN: 0006-291X; 1090-2104; 1090-2104
• DOI: 10.1016/j.bbrc.2024.150990

The multifunctional promyelocytic leukemia protein (PML) is involved in the regulation of various cellular processes in both physiological and pathological conditions. Specifically, PML is one of the inositol-1,4,5-trisphosphate receptors (IP3Rs) activity regulators and can influence Ca2+ transport from the endoplasmic reticulum (ER) to mitochondria. In this work, the effects of PML knockout on calcium homeostasis in the cytosol, ER, and mitochondria of HeLa cells were studied upon stimulation with histamine, which induces Ca2+ mobilization from the ER via IP3Rs. We utilized calcium indicators with different subcellular localizations, including synthetic dyes Fura-2 (cytosolic), Xrhod-5F (mitochondrial), and protein sensor R-CEPIAer (ER), as well as mitochondrial potential-sensitive probes Rh123 and TMRM. Our results show that PML knockout induced changes in HeLa cell and mitochondrial morphology, slightly decreased basal and integral Ca2+ levels, enhanced mitochondrial Ca2+ uptake from the cytoplasm, and maintained residual mitochondrial potential after depolarization. Additionally, it reduced the Ca2+ pool in ER membranes not associated with histamine receptor activation and, consequently, IP3Rs. These findings suggest that changes in calcium ion transport due to PML knockout in HeLa cells affect mitochondrial activity. •PML knockout changes HeLa cell morphology.•PML knockout enhances mitochondrial calcium uptake from the cytoplasm, and affects the Ca2⁺ storage capacity in ER compartments.•PML knockout opposes protonophore-induced mitochondrial potential decrease.