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- Sterlini, B, et al.
(författare)
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An interaction between PRRT2 and Na+/K+ ATPase contributes to the control of neuronal excitability
- 2021
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Ingår i: Cell death & disease. - : Springer Science and Business Media LLC. - 2041-4889. ; 12:4, s. 292-
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Tidskriftsartikel (refereegranskat)abstract
- Mutations in PRoline Rich Transmembrane protein 2 (PRRT2) cause pleiotropic syndromes including benign infantile epilepsy, paroxysmal kinesigenic dyskinesia, episodic ataxia, that share the paroxysmal character of the clinical manifestations. PRRT2 is a neuronal protein that plays multiple roles in the regulation of neuronal development, excitability, and neurotransmitter release. To better understand the physiopathology of these clinical phenotypes, we investigated PRRT2 interactome in mouse brain by a pulldown-based proteomic approach and identified α1 and α3 Na+/K+ ATPase (NKA) pumps as major PRRT2-binding proteins. We confirmed PRRT2 and NKA interaction by biochemical approaches and showed their colocalization at neuronal plasma membrane. The acute or constitutive inactivation of PRRT2 had a functional impact on NKA. While PRRT2-deficiency did not modify NKA expression and surface exposure, it caused an increased clustering of α3-NKA on the plasma membrane. Electrophysiological recordings showed that PRRT2-deficiency in primary neurons impaired NKA function during neuronal stimulation without affecting pump activity under resting conditions. Both phenotypes were fully normalized by re-expression of PRRT2 in PRRT2-deficient neurons. In addition, the NKA-dependent afterhyperpolarization that follows high-frequency firing was also reduced in PRRT2-silenced neurons. Taken together, these results demonstrate that PRRT2 is a physiological modulator of NKA function and suggest that an impaired NKA activity contributes to the hyperexcitability phenotype caused by PRRT2 deficiency.
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| 4. |
- Lal, M. A., et al.
(författare)
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Role of oxidative stress in advanced glycation end product-induced mesangial cell activation
- 2002
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Ingår i: Kidney International. - : Elsevier BV. - 0085-2538 .- 1523-1755. ; 61:6, s. 2006-2014
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Tidskriftsartikel (refereegranskat)abstract
- Background. Levels of advanced glycation end products (AGE) are elevated in individuals with advancing age, renal failure, and diabetes, and accumulation of these molecules may contribute to disease progression. The mechanism by which AGE proteins alter glomerular mesangial cell function, however, is not completely understood. The present study assessed the involvement of oxidative stress in AGE-dependent mesangial cell signaling events. Methods. Primary cultures of rat renal mesangial cells were exposed to in vitro AGE-BSA and H-2 O-2 . Nuclear factor-kappaB (NF-kappaB) and protein kinase C (PKC) isoform activation were studied using confocal microscopy and Western blotting. Quantitative polymerase chain reaction (PCR) was used to measure transforming growth factor-beta1 (TGF-beta1) levels. The involvement of oxidative stress was assessed by supplementing or compromising cellular antioxidant capacity. Results. NF-kappaB was dose-dependently activated by AGE. PKC activation was not involved in this response, but analysis of PKC-beta1 activation showed a stimulatory effect of AGE proteins on this isoform. Transcription of TGF-beta1 was stimulated by AGE and was prevented by PKC inhibition. Challenge with H-2 O-2 had similar downstream effects on mesangial cell signaling. Antioxidants, vitamin E and nitecapone, prevented AGE-dependent NF-kappaB activation and normalized PKC activity and associated TGF-beta1 transcription. Depletion of the intracellular antioxidant, glutathione, effectively lowered the AGE concentration needed for mesangial cell activation of NF-kappaB and PKC-beta1. Treatment with a suboptimal AGE dose, under glutathione-depleted conditions, revealed a synergistic effect on both parameters. Conclusion. The results support a central role for oxidative stress in AGE-dependent mesangial cell signaling and emphasize the importance of ROS in determining cell responsiveness.
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| 6. |
- Uhlen, P., et al.
(författare)
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alpha-Haemolysin of uropathogenic E-coli induces Ca2+ oscillations in renal epithelial cells
- 2000
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 405:6787, s. 694-697
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Tidskriftsartikel (refereegranskat)abstract
- Pyelonephritis is one of the most common febrile diseases in children. If not treated appropriately, it causes irreversible renal damage and accounts for a large proportion of end stage renal failures(1). Renal scarring can occur in the absence of inflammatory cells, indicating that bacteria may have a direct signalling effect on renal cells(2). Intracellular calcium ([Ca2+](i)) oscillations can protect cells from the cytotoxic effects of prolonged increases in intracellular calcium(3,4). However, no pathophysiologically relevant protein that induces such oscillations has been identified. Here we show that infection by uropathogenic Escherichia coli induces a constant, low-frequency oscillatory [Ca2+](i) response in target primary rat renal epithelial cells induced by the secreted RTX (repeats-in-toxin) toxin alpha-haemolysin. The response depends on calcium influx through L-type calcium channels as well as from internal stores gated by inositol triphosphate. Internal calcium oscillations induced by alpha-haemolysin in a renal epithelial cell line stimulated production of cytokines interleukin (IL)-6 and IL-8. Our findings indicate a novel role for alpha-haemolysin in pyelonephritis: as an inducer of an oscillating second messenger response in target cells, which fine-tunes gene expression during the inflammatory response.
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| 7. |
- Zelenina, M., et al.
(författare)
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Water permeability of aquaporin-4 is decreased by protein kinase C and dopamine
- 2002
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Ingår i: American Journal of Physiology - Renal Physiology. - : American Physiological Society. - 0363-6127 .- 1522-1466 .- 1931-857X. ; 283:2, s. F309-F318
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Tidskriftsartikel (refereegranskat)abstract
- Aquaporin-4 (AQP4) plays an important role in the basolateral movement of water in the collecting duct. Here we show that this water channel can be dynamically regulated. Water permeability (P-f) was measured in individual LLC-PK1 cells that were transiently transfected with AQP4. To identify which cells were transfected, AQP4 was tagged at the NH2 terminus with green fluorescent protein. Transfected cells showed a strong fluorescent signal in basolateral membrane and a low-to-negligible signal in the cytosol and apical membrane. Activation of protein kinase C (PKC) with phorbol 12,13-dibutyrate (PDBu) significantly decreased P-f of cells expressing AQP4 but had no effect on neighboring untransfected cells. No redistribution of AQP4 in response to PDBu was detected. Dopamine also decreased the P-f in transfected cells. The effect was abolished by the PKC inhibitor Ro 31-8220. Reduction of AQP4 water permeability by PDBu and dopamine was abolished by point mutation of Ser(180), a consensus site for PKC phosphorylation. We conclude that PKC and dopamine decrease AQP4 water permeability via phosphorylation at Ser(180) and that the effect is likely mediated by gating of the channel.
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| 8. |
- Aizman, O, et al.
(författare)
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Anatomical and physiological evidence for D-1 and D-2 dopamine receptor colocalization in neostriatal neurons
- 2000
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Ingår i: Nature Neuroscience. - : Springer Science and Business Media LLC. - 1097-6256 .- 1546-1726. ; 3:3, s. 226-230
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Tidskriftsartikel (refereegranskat)abstract
- Despite the importance of dopamine signaling, it remains unknown if the two major subclasses of dopamine receptors exist on the same or distinct populations of neurons. Here we used confocal microscopy to demonstrate that virtually all striatal neurons, both in vitro and in vivo, contained dopamine receptors of both classes. We also provide functional evidence for such colocalization: in essentially all neurons examined, fenoldopam, an agonist of the D-1 subclass of receptors, inhibited both the Na+/K+ pump and tetrodotoxin (TTX)-sensitive sodium channels, and quinpirole, an agonist of the Dr subclass of receptors, activated TTX-sensitive sodium channels. Thus D-1 and D-2 classes of ligands may functionally interact in virtually all dopamine-responsive neurons within the basal ganglia.
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| 9. |
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| 10. |
- Bottger, P, et al.
(författare)
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Glutamate-system defects behind psychiatric manifestations in a familial hemiplegic migraine type 2 disease-mutation mouse model
- 2016
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Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6, s. 22047-
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Tidskriftsartikel (refereegranskat)abstract
- Migraine is a complex brain disorder, and understanding the complexity of this prevalent disease could improve quality of life for millions of people. Familial Hemiplegic Migraine type 2 (FHM2) is a subtype of migraine with aura and co-morbidities like epilepsy/seizures, cognitive impairments and psychiatric manifestations, such as obsessive-compulsive disorder (OCD). FHM2 disease-mutations locate to the ATP1A2 gene encoding the astrocyte-located α2-isoform of the sodium-potassium pump (α2Na+/K+-ATPase). We show that knock-in mice heterozygous for the FHM2-associated G301R-mutation (α2+/G301R) phenocopy several FHM2-relevant disease traits e.g., by mimicking mood depression and OCD. In vitro studies showed impaired glutamate uptake in hippocampal mixed astrocyte-neuron cultures from α2G301R/G301R E17 embryonic mice, and moreover, induction of cortical spreading depression (CSD) resulted in reduced recovery in α2+/G301R male mice. Moreover, NMDA-type glutamate receptor antagonists or progestin-only treatment reverted specific α2+/G301R behavioral phenotypes. Our findings demonstrate that studies of an in vivo relevant FHM2 disease knock-in mouse model provide a link between the female sex hormone cycle and the glutamate system and a link to co-morbid psychiatric manifestations of FHM2.
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