TY  - JOUR
A1  - Planes, Maria D.
A1  - Niñoles, Regina
A1  - Rubio, Lourdes
A1  - Bissoli, Gaetano
A1  - Bueso, Eduardo
A1  - García-Sánchez, María J.
A1  - Alejandro, Santiago
A1  - Gonzalez-Guzmán, Miguel
A1  - Hedrich, Rainer
A1  - Rodriguez, Pedro L.
A1  - Fernández, José A.
A1  - Serrano, Ramón
T1  - A mechanism of growth inhibition by abscisic acid in germinating seeds of Arabidopsis thaliana based on inhibition of plasma membrane \(H^+\)-ATPase and decreased cytosolic pH, \(K^+\), and anions
JF  - Journal of Experimental Botany
N2  - The stress hormone abscisic acid (ABA) induces expression of defence genes in many organs, modulates ion homeostasis and metabolism in guard cells, and inhibits germination and seedling growth. Concerning the latter effect, several mutants of Arabidopsis thaliana with improved capability for \(H^+\) efflux (wat1-1D, overexpression of AKT1 and ost2-1D) are less sensitive to inhibition by ABA than the wild type. This suggested that ABA could inhibit \(H^+\) efflux (\(H^+\)-ATPase) and induce cytosolic acidification as a mechanism of growth inhibition. Measurements to test this hypothesis could not be done in germinating seeds and we used roots as the most convenient system. ABA inhibited the root plasma-membrane H+-ATPase measured in vitro (ATP hydrolysis by isolated vesicles) and in vivo (\(H^+\) efflux from seedling roots). This inhibition involved the core ABA signalling elements: PYR/PYL/RCAR ABA receptors, ABA-inhibited protein phosphatases (HAB1), and ABA-activated protein kinases (SnRK2.2 and SnRK2.3). Electrophysiological measurements in root epidermal cells indicated that ABA, acting through the PYR/PYL/RCAR receptors, induced membrane hyperpolarization (due to \(K^+\) efflux through the GORK channel) and cytosolic acidification. This acidification was not observed in the wat1-1D mutant. The mechanism of inhibition of the \(H^+\)-ATPase by ABA and its effects on cytosolic pH and membrane potential in roots were different from those in guard cells. ABA did not affect the in vivo phosphorylation level of the known activating site (penultimate threonine) of (\(H^+\)-ATPase in roots, and SnRK2.2 phosphorylated in vitro the C-terminal regulatory domain of (\(H^+\)-ATPase while the guard-cell kinase SnRK2.6/OST1 did not.
KW  - ABA receptors
KW  - cytosolic pH
KW  - ion channels
KW  - microelectrodes
KW  - protein kinase
KW  - proton efflux
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-121221
VL  - 66
IS  - 3
ER  - 
TY  - JOUR
A1  - Bittner, Stefan
A1  - Bobak, Nicole
A1  - Hofmann, Majella-Sophie
A1  - Schuhmann, Michael K.
A1  - Ruck, Tobias
A1  - Göbel, Kerstin
A1  - Brück, Wolfgang
A1  - Wiendl, Heinz
A1  - Meuth, Sven G.
T1  - Murine K\(_{2P}\)5.1 Deficiency Has No Impact on Autoimmune Neuroinflammation due to Compensatory K\(_{2P}\)3.1-and K\(_{V}\)1.3-Dependent Mechanisms
JF  - International Journal of Molecular Sciences
N2  - Lymphocytes express potassium channels that regulate physiological cell functions, such as activation, proliferation and migration. Expression levels of K\(_{2P}\)5.1(TASK2; KCNK5) channels belonging to the family of two-pore domain potassium channels have previously been correlated to the activity of autoreactive T lymphocytes in patients with multiple sclerosis and rheumatoid arthritis. In humans, K\(_{2P}\)5.1 channels are upregulated upon T cell stimulation and influence T cell effector functions. However, a further clinical translation of targeting K\(_{2P}\)5.1 is currently hampered by a lack of highly selective inhibitors, making it necessary to evaluate the impact of KCNK5 in established preclinical animal disease models. We here demonstrate that K\(_{2P}\)5.1 knockout (K\(_{2P}\)5.1\(^{-/-}\) mice display no significant alterations concerning T cell cytokine production, proliferation rates, surface marker molecules or signaling pathways. In an experimental model of autoimmune neuroinflammation, K\(_{2P}\)5.1\(^{-/-}\) mice show a comparable disease course to wild-type animals and no major changes in the peripheral immune system or CNS compartment. A compensatory upregulation of the potassium channels K\(_{2P}\)3.1 and K\(_{V}\)1.3 seems to counterbalance the deletion of K\(_{2P}\)5.1. As an alternative model mimicking autoimmune neuroinflammation, experimental autoimmune encephalomyelitis in the common marmoset has been proposed, especially for testing the efficacy of new potential drugs. Initial experiments show that K\(_{2P}\)5.1 is functionally expressed on marmoset T lymphocytes, opening up the possibility for assessing future K\(_{2P}\)5.1-targeting drugs.
KW  - domain potassium channels
KW  - volume regulation
KW  - multiple-sclerosis
KW  - potassium channels
KW  - multiple sclerosis
KW  - ion channels
KW  - K+ channel
KW  - T lymphocytes
KW  - up-regulation
KW  - TASK2
KW  - K2P channels
KW  - B cells
KW  - ph
KW  - K\(_{2P}\)5.1
KW  - KCNK5
KW  - autoimmune neuroinflammation
KW  - EAE
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-151454
VL  - 16
SP  - 16880
EP  - 16896
ER  - 
TY  - JOUR
A1  - Spitzel, Marlene
A1  - Wagner, Elise
A1  - Breyer, Maximilian
A1  - Henniger, Dorothea
A1  - Bayin, Mehtap
A1  - Hofmann, Lukas
A1  - Mauceri, Daniela
A1  - Sommer, Claudia
A1  - Üçeyler, Nurcan
T1  - Dysregulation of immune response mediators and pain-related ion channels is associated with pain-like behavior in the GLA KO mouse model of Fabry disease
JF  - Cells
N2  - Fabry disease (FD) is a rare life-threatening disorder caused by deficiency of the alpha-galactosidase A (GLA) enzyme with a characteristic pain phenotype. Impaired GLA production or function leads to the accumulation of the cell membrane compound globotriaosylceramide (Gb3) in the neurons of the dorsal root ganglia (DRG) of FD patients. Applying immunohistochemistry (IHC) and quantitative real-time polymerase chain reaction (qRT PCR) analysis on DRG tissue of the GLA knockout (KO) mouse model of FD, we address the question of how Gb3 accumulation may contribute to FD pain and focus on the immune system and pain-associated ion channel gene expression. We show a higher Gb3 load in the DRG of young (<6 months) (p < 0.01) and old (≥12 months) (p < 0.001) GLA KO mice compared to old wildtype (WT) littermates, and an overall suppressed immune response in the DRG of old GLA KO mice, represented by a reduced number of CD206\(^+\) macrophages (p < 0.01) and lower gene expression levels of the inflammation-associated targets interleukin(IL)1b (p < 0.05), IL10 (p < 0.001), glial fibrillary acidic protein (GFAP) (p < 0.05), and leucine rich alpha-2-glycoprotein 1 (LRG1) (p < 0.01) in the DRG of old GLA KO mice compared to old WT. Dysregulation of immune-related genes may be linked to lower gene expression levels of the pain-associated ion channels calcium-activated potassium channel 3.1 (KCa3.1) and transient receptor potential ankyrin 1 channel (TRPA1). Ion channel expression might further be disturbed by impaired sphingolipid recruitment mediated via the lipid raft marker flotillin-1 (FLOT1). This impairment is represented by an increased number of FLOT1\(^+\) DRG neurons with a membranous expression pattern in old GLA KO mice compared to young GLA KO, young WT, and old WT mice (p < 0.001 each). Further, we provide evidence for aberrant behavior of GLA KO mice, which might be linked to dysregulated ion channel gene expression levels and disturbed FLOT1 distribution patterns. Behavioral testing revealed mechanical hypersensitivity in young (p < 0.01) and old (p < 0.001) GLA KO mice compared to WT, heat hypersensitivity in young GLA KO mice (p < 0.001) compared to WT, age-dependent heat hyposensitivity in old GLA KO mice (p < 0.001) compared to young GLA KO mice, and cold hyposensitivity in young (p < 0.001) and old (p < 0.001) GLA KO mice compared to WT, which well reflects the clinical phenotype observed in FD patients.
KW  - Fabry disease
KW  - globotriaosylceramide
KW  - inflammation
KW  - macrophages
KW  - cytokines
KW  - ion channels
KW  - flotillin-1 lipid rafts
KW  - pain-associated behavior
KW  - mouse model
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-275186
SN  - 2073-4409
VL  - 11
IS  - 11
ER  -