TY  - JOUR
A1  - Korb, Doreen
A1  - Tng, Priscilla Y.
A1  - Milenkovic, Vladimir M.
A1  - Reichhart, Nadine
A1  - Strauss, Olaf
A1  - Ritter, Oliver
A1  - Fischer, Tobias
A1  - Benz, Peter M.
A1  - Schuh, Kai
T1  - Identification of PDZ domain containing proteins interacting with \(Ca_v1.2\) and PMCA4b
JF  - ISRN Cell Biology
N2  - PDZ (PSD-95/Disc large/Zonula occludens-1) protein interaction domains bind to cytoplasmic protein C-termini of transmembrane proteins. In order to identify new interaction partners of the voltage-gated L-type \(Ca^{2+}\) channel Cav1.2 and the plasma membrane \(Ca^{2+}\) ATPase 4b (PMCA4b), we used PDZ domain arrays probing for 124 PDZ domains. We confirmed this byGST pulldowns and immunoprecipitations. In PDZ arrays, strongest interactionswith \(Ca_v1.2\) and PMCA4b were found for the PDZ domains of SAP-102, MAST-205, MAGI-1, MAGI-2, MAGI-3, and ZO-1. We observed binding of the \(Ca_v1.2\) C-terminus to PDZ domains of NHERF1/2, Mint-2, and CASK. PMCA4b was observed to interact with Mint-2 and its known interactions with Chapsyn-110 and CASK were confirmed. Furthermore, we validated interaction of \(Ca_v1.2\) and PMCA4b with NHERF1/2, CASK,MAST-205 and MAGI-3 viaimmunoprecipitation. We also verified the interaction of \(Ca_v1.2\) and nNOS and hypothesized that nNOS overexpression might reduce \(Ca^{2+}\) influx through \(Ca_v1.2\). To address this, we measured \(Ca^{2+}\) currents in HEK 293 cells co-expressing \(Ca_v1.2\) and nNOS and observed reduced voltage-dependent \(Ca_v1.2\) activation. Taken together, we conclude that \(Ca_v1.2\) and PMCA4b bind promiscuously to various PDZ domains, and that our data provides the basis for further investigation of the physiological consequences of these interactions.
KW  - Cell
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-130585
IS  - Article ID 265182
ER  - 
TY  - JOUR
A1  - Benz, Peter M.
A1  - Merkel, Carla J.
A1  - Offner, Kristin
A1  - Abeßer, Marco
A1  - Ullrich, Melanie
A1  - Fischer, Tobias
A1  - Bayer, Barbara
A1  - Wagner, Helga
A1  - Gambaryan, Stepan
A1  - Ursitti, Jeanine A.
A1  - Adham, Ibrahim M.
A1  - Linke, Wolfgang A.
A1  - Feller, Stephan M.
A1  - Fleming, Ingrid
A1  - Renné, Thomas
A1  - Frantz, Stefan
A1  - Unger, Andreas
A1  - Schuh, Kai
T1  - Mena/VASP and alphaII-Spectrin complexes regulate cytoplasmic actin networks in cardiomyocytes and protect from conduction abnormalities and dilated cardiomyopathy
JF  - Cell Communication and Signaling
N2  - Background: In the heart, cytoplasmic actin networks are thought to have important roles in mechanical support, myofibrillogenesis, and ion channel function. However, subcellular localization of cytoplasmic actin isoforms and proteins involved in the modulation of the cytoplasmic actin networks are elusive. Mena and VASP are important regulators of actin dynamics. Due to the lethal phenotype of mice with combined deficiency in Mena and VASP, however, distinct cardiac roles of the proteins remain speculative. In the present study, we analyzed the physiological functions of Mena and VASP in the heart and also investigated the role of the proteins in the organization of cytoplasmic actin networks.
Results: We generated a mouse model, which simultaneously lacks Mena and VASP in the heart. Mena/VASP double-deficiency induced dilated cardiomyopathy and conduction abnormalities. In wild-type mice, Mena and VASP specifically interacted with a distinct αII-Spectrin splice variant (SH3i), which is in cardiomyocytes exclusively localized at Z- and intercalated discs. At Z- and intercalated discs, Mena and β-actin localized to the edges of the sarcomeres, where the thin filaments are anchored. In Mena/VASP double-deficient mice, β-actin networks were disrupted and the integrity of Z- and intercalated discs was markedly impaired.
Conclusions: Together, our data suggest that Mena, VASP, and αII-Spectrin assemble cardiac multi-protein complexes, which regulate cytoplasmic actin networks. Conversely, Mena/VASP deficiency results in disrupted β-actin assembly, Z- and intercalated disc malformation, and induces dilated cardiomyopathy and conduction abnormalities.
KW  - Mena/VASP
KW  - dilated cardiomyopathy
KW  - actin
KW  - heart
KW  - spectrin
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-128760
VL  - 11
IS  - 56
ER  - 
TY  - THES
A1  - Fischer, Tobias
T1  - Ein Radioimmunoassay (RIA) für die Messung von Dehydroepiandrosteron (DHEA) im Speichel
T1  - A radioimmoassay (Ria) for measurement of dehydroepiandrosterone (DHEA) in saliva
N2  - Die Messung von Steroidhormonen im Speichel hat viele Vorteile verglichen mit der Messung im Serum. Durch Modifikation eines handelsüblichen Testkits für die Messung von DHEA im Serum stellen wir einen Radioimmunoassay für die Messung im Speichel vor. Der Testkit wurde in seiner Stabilität, Prezision und einfacher Handhabung validiert. Die Korrelation zwischen Serum und Speichel war hoch. Junge Probanden zeigten eine zirkadiane Rhythmik der DHEA-Speichelwerte. In einer Studie mit Schulkindern zwischen 3 und 12 Jahren fand sich ein signifikanter Anstieg der DHEA-Werte in der Altersgruppe 7 bis 10 als Hinweis auf die Adrenarche. Speichelproben von Probanden einer Substitutionsstudie mit DHEA i.m. zeigten einen Anstieg der Werte ab dem 2. Tag. Des weiteren werden Empfehlungen zur Sammlung und Vorbereitung von Speichelproben zur Messung von Steroidhormonen gegeben.
N2  - The measurement of steroidhormones in saliva has many advantages compared with the measurement in serum. Through modification of a commercial testkit for Dhea in serum we present a radioimmunoassay for Dhea in saliva. The modified testkit is validated in stability, precision and comfortable handling. The correlation of serum and saliva values was high. The saliva of young probands showed a circadian rhythm. In a study with children from 3 to 12 years was a significant rise of Dhea between 7 and 10 years, the age group of the adrenarche. Probes of a substitution study with Dhea given i.m. showed a peak of saliva values from the 2. day. Advice for collecting and preparing of saliva for the measurement of steroidhormones is given.
KW  - Dehydroepiandrosteron
KW  - Radioimmunoassay
KW  - Speichel
KW  - dehydroepiandrosterone
KW  - radioimmunoassay
KW  - saliva
Y1  - 2004
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-8343
ER  -