TY  - JOUR
A1  - Breitinger, Ulrike
A1  - Bahnassawy, Lamiaa M.
A1  - Janzen, Dieter
A1  - Römer, Vera
A1  - Becker, Cord-Michael
A1  - Villmann, Carmen
A1  - Breitinger, Hans-Georg
T1  - PKA and PKC modulators affect ion channel function and internalization of recombinant alpha1 and alpha1-beta glycine receptors
JF  - Frontiers in Molecular Neurosience
N2  - Glycine receptors (GlyRs) are important mediators of fast inhibitory neurotransmission in the mammalian central nervous system. Their function is controlled by multiple cellular mechanisms, including intracellular regulatory processes. Modulation of GlyR function by protein kinases has been reported for many cell types, involving different techniques, and often yielding contradictory results. Here, we studied the effects of protein kinase C (PKC) and cAMP-dependent protein kinase A (PKA) on glycine induced currents in HEK293 cells expressing human homomeric \(\alpha\)1 and heteromeric \(\alpha\)1-\(\beta\) GlyRs using whole-cell patch clamp techniques as well as internalization assays. In whole-cell patch-clamp measurements, modulators were applied in the intracellular buffer at concentrations between 0.1 \(\mu\)M and 0.5 \(\mu\)M. EC50 of glycine increased upon application of the protein kinase activators Forskolin and phorbol-12-myristate-13-acetate (PMA) but decreased in the presence of the PKC inhibitor Staurosporine aglycon and the PKA inhibitor H-89. Desensitization of recombinant \(\alpha\)1 receptors was significantly increased in the presence of Forskolin. Staurosporine aglycon, on the other hand decreased desensitization of heteromeric \(\alpha\)1-\(\beta\) GlyRs. The time course of receptor activation was determined for homomeric \(\alpha\)1 receptors and revealed two simultaneous effects: cells showed a decrease of EC50 after 3-6 min of establishing whole-cell configuration. This effect was independent of protein kinase modulators. All modulators of PKA and PKC, however, produced an additional shift of EC50, which overlay and eventually exceeded the cells intrinsic variation of EC50. The effect of kinase activators was abolished if the corresponding inhibitors were co-applied, consistent with PKA and PKC directly mediating the modulation of GlyR function. Direct effects of PKA-and PKC-modulators on receptor expression on transfected HEK cells were monitored within 15 min of drug application, showing a significant increase of receptor internalization with PKA and PKC activators, while the corresponding inhibitors had no significant effect on receptor surface expression or internalization. Our results confirm the observation that phosphorylation via PKA and PKC has a direct effect on the GlyR ion channel complex and plays an important role in the fine-tuning of glycinergic signaling.
KW  - glycine receptor
KW  - PKA
KW  - PKC
KW  - activators/inhibitors of phosphorylation
KW  - whole-cell currents
KW  - modulation kinetics
KW  - receptor internalization
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-220401
VL  - 11
ER  - 
TY  - JOUR
A1  - Lorenz, Kristina
A1  - Rosner, Marsha Rich
T1  - Harnessing RKIP to combat heart disease and cancer
JF  - Cancers
N2  - Cancer and heart disease are leading causes of morbidity and mortality worldwide. These diseases have common risk factors, common molecular signaling pathways that are central to their pathogenesis, and even some disease phenotypes that are interdependent. Thus, a detailed understanding of common regulators is critical for the development of new and synergistic therapeutic strategies. The Raf kinase inhibitory protein (RKIP) is a regulator of the cellular kinome that functions to maintain cellular robustness and prevent the progression of diseases including heart disease and cancer. Two of the key signaling pathways controlled by RKIP are the β-adrenergic receptor (βAR) signaling to protein kinase A (PKA), particularly in the heart, and the MAP kinase cascade Raf/MEK/ERK1/2 that regulates multiple diseases. The goal of this review is to discuss how we can leverage RKIP to suppress cancer without incurring deleterious effects on the heart. Specifically, we discuss: (1) How RKIP functions to either suppress or activate βAR (PKA) and ERK1/2 signaling; (2) How we can prevent cancer-promoting kinase signaling while at the same time avoiding cardiotoxicity.
KW  - RKIP
KW  - ERK1/2
KW  - PKA
KW  - βAR
KW  - heart failure
KW  - cancer
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-262185
SN  - 2072-6694
VL  - 14
IS  - 4
ER  -