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- Bernhem, Kristoffer, et al.
(författare)
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Super-resolution microscopy reveals that Na+/K+-ATPase signaling protects against glucose-induced apoptosis by deactivating Bad
- 2021
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Ingår i: Cell Death and Disease. - : Springer Nature. - 2041-4889 .- 2041-4889. ; 12:8
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Tidskriftsartikel (refereegranskat)abstract
- Activation of the apoptotic pathway is a major cause of progressive loss of function in chronic diseases such as neurodegenerative and diabetic kidney diseases. There is an unmet need for an anti-apoptotic drug that acts in the early stage of the apoptotic process. The multifunctional protein Na+,K+-ATPase has, in addition to its role as a transporter, a signaling function that is activated by its ligand, the cardiotonic steroid ouabain. Several lines of evidence suggest that sub-saturating concentrations of ouabain protect against apoptosis of renal epithelial cells, a common complication and major cause of death in diabetic patients. Here, we induced apoptosis in primary rat renal epithelial cells by exposing them to an elevated glucose concentration (20mM) and visualized the early steps in the apoptotic process using super-resolution microscopy. Treatment with 10nM ouabain interfered with the onset of the apoptotic process by inhibiting the activation of the BH3-only protein Bad and its translocation to mitochondria. This occurred before the pro-apoptotic protein Bax had been recruited to mitochondria. Two ouabain regulated and Akt activating Ca2+/calmodulin-dependent kinases were found to play an essential role in the ouabain anti-apoptotic effect. Our results set the stage for further exploration of ouabain as an anti-apoptotic drug in diabetic kidney disease as well as in other chronic diseases associated with excessive apoptosis.
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- Fontana, Jacopo M., et al.
(författare)
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Calcium oscillations triggered by cardiotonic steroids
- 2013
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Ingår i: The FEBS Journal. - : Wiley. - 1742-464X .- 1742-4658. ; 280:21, s. 5450-5455
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Forskningsöversikt (refereegranskat)abstract
- Na+, K+-ATPase (NKA) is well known for its function as an ion pump. Studies during the last decade have revealed an additional role for NKA as a signal transducer. In this brief review, we describe how cardiotonic steroids, which are highly specific NKA ligands, trigger slow Ca2+ oscillations by promoting the interaction between NKA and the inositol trisphosphate receptor, and how this Ca2+ signal activates the NF-B subunit p65 and increases the expression of the antiapoptotic factor Bcl-xL. The potential tissue-protective effects of this signal are discussed.
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- Fontana, Jacopo M., et al.
(författare)
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Spontaneous calcium activity in metanephric mesenchymal cells regulates branching morphogenesis in the embryonic kidney
- 2019
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Ingår i: The FASEB Journal. - : FEDERATION AMER SOC EXP BIOL. - 0892-6638 .- 1530-6860. ; 33:3, s. 4089-4096
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Tidskriftsartikel (refereegranskat)abstract
- The central role of calcium signaling during development of early vertebrates is well documented, but little is known about its role in mammalian embryogenesis. We have used immunofluorescence and time-lapse calcium imaging of cultured explanted embryonic rat kidneys to study the role of calcium signaling for branching morphogenesis. In mesenchymal cells, we recorded spontaneous calcium activity that was characterized by irregular calcium transients. The calcium signals were dependent on release of calcium from intracellular stores in the endoplasmic reticulum. Down-regulation of the calcium activity, both by blocking the sarco-endoplasmic reticulum Ca2+-ATPase and by chelating cytosolic calcium, resulted in retardation of branching morphogenesis and a reduced formation of primitive nephrons but had no effect on cell proliferation. We propose that spontaneous calcium activity contributes with a stochastic factor to the self-organizing process that controls branching morphogenesis, a major determinant of the ultimate number of nephrons in the kidney.Fontana, J. M., Khodus, G. R., Unnersjo-Jess, D., Blom, H., Aperia, A., Brismar, H. Spontaneous calcium activity in metanephric mesenchymal cells regulates branching morphogenesis in the embryonic kidney.
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| 7. |
- Panizza, Elena, et al.
(författare)
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Ouabain-regulated phosphoproteome reveals molecular mechanisms for Na+, K+-ATPase control of cell adhesion, proliferation, and survival
- 2019
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Ingår i: The FASEB Journal. - : FEDERATION AMER SOC EXP BIOL. - 0892-6638 .- 1530-6860. ; 33:9, s. 10193-10206
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Tidskriftsartikel (refereegranskat)abstract
- The ion pump Na+, K+-ATPase (NKA) is a receptor for the cardiotonic steroid ouabain. Subsaturating concentration of ouabain triggers intracellular calcium oscillations, stimulates cell proliferation and adhesion, and protects from apoptosis. However, it is controversial whether ouabain-bound NKA is considered a signal transducer. To address this question, we performed a global analysis of protein phosphorylation in COS-7 cells, identifying 2580 regulated phosphorylation events on 1242 proteins upon 10- and 20-min treatment with ouabain. Regulated phosphorylated proteins include the inositol triphosphate receptor and stromal interaction molecule, which are essential for initiating calcium oscillations. Hierarchical clustering revealed that ouabain triggers a structured phosphorylation response that occurs in a well-defined, time-dependent manner and affects specific cellular processes, including cell proliferation and cell-cell junctions. We additionally identify regulation of the phosphorylation of several calcium and calmodulin-dependent protein kinases (CAMKs), including 2 sites of CAMK type II-gamma (CAMK2G), a protein known to regulate apoptosis. To verify the significance of this result, CAMK2G was knocked down in primary kidney cells. CAMK2G knockdown impaired ouabain-dependent protection from apoptosis upon treatment with high glucose or serum deprivation. In conclusion, we establish NKA as the coordinator of a broad, tightly regulated phosphorylation response in cells and define CAMK2G as a downstream effector of NKA.-Panizza, E., Zhang, L., Fontana, J. M., Hamada, K., Svensson, D., Akkuratov, E. E., Scott, L., Mikoshiba, K., Brismar, H., Lehtio, J., Aperia, A. Ouabain-regulated phosphoproteome reveals molecular mechanisms for Na+, K+-ATPase control of cell adhesion, proliferation, and survival.
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- Yin, Huijuan, et al.
(författare)
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Quantum dots modulate intracellular Ca2+ level in lung epithelial cells
- 2017
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Ingår i: International Journal of Nanomedicine. - : DOVE MEDICAL PRESS LTD. - 1176-9114 .- 1178-2013. ; 12, s. 2781-2792
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Tidskriftsartikel (refereegranskat)abstract
- While adverse effects of nanoparticles on lung health have previously been proposed, few studies have addressed the direct effects of nanoparticle exposure on the airway epithelium. In this work, we examine the response of the pulmonary airway to nanoparticles by measuring intracellular Ca2+ concentration ([Ca2+](i)) in the Calu-3 epithelial layer stimulated by 3-mercaptopropionic-acid (3MPA) coated CdSe-CdS/ZnS core-multishell quantum dots (QDs). Simultaneous transient transepithelial electrical resistance (TEER) decrease and global [Ca2+](i) increase in Calu-3 epithelial layer, accompanied by cell displacements, contraction, and expansion, were observed under QD deposition. This suggests that a QD-induced global [Ca2+](i) increase in the Calu-3 epithelial layer caused the transient TEER decrease. The [Ca2+](i) increase was marked and rapid in the apical region, while [Ca2+](i) decreased in the basolateral region of the epithelial layer. TEER transient response and extracellular Ca2+ entry induced by QD deposition were completely inhibited in cells treated with stretched-activated (SA) inhibitor GdCl3 and store-operated calcium entry (SOCE) inhibitor BTP2 and in cells immersed in Ca2+-free medium. The voltage-gated calcium channel (VGCC) inhibitor nifedipine decreased, stabilized, and suppressed the TEER response, but did not affect the [Ca2+](i) increase, due to QD deposition. This demonstrates that the Ca2+ influx activated by QDs' mechanical stretch occurs through activation of both SA and SOCE channels. QD-induced [Ca2+](i) increase occurred in the Calu-3 epithelial layer after culturing for 15 days, while significant TEER drop only occurred after 23 days. This work provides a new perspective from which to study direct interactions between airway epithelium and nanoparticles and may help to reveal the pathologies of pulmonary disease.
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