Adelfinger, Lisa. Modulation of GABAB receptor signaling by associated proteins and phosphorylation. 2014, PhD Thesis, University of Basel, Faculty of Science.
Restricted to Repository staff only until 26 November 2017.
Official URL: http://edoc.unibas.ch/diss/DissB_11077
The first part of this thesis uncovers the mechanism of GABAB receptor-activated K+ current desensitization induced by KCTD12. Besides the constitutive binding of all KCTDs to the G-protein, selectively KCTD12 has a second binding site on the activated Gß? subunit. A switch in binding uncouples Gß? from the K+ channels and induces K+ current desensitization. Native KCTD12 associates exclusively with GABAB receptors rendering this mechanism receptor specific. (Turecek et al., 2014)
In the second part, we investigated the effects of GABAB receptor phosphorylation on KCTD12-induced K+ current desensitization. Phosphorylation of serine-892 (S892) in GABAB2 by protein kinase A (PKA) was previously described as a rather slow mechanism to regulate GABAB receptor desensitization (Couve et al., 2002). In contrast, KCTD12-induced desensitization of GABAB receptor-activated K+ currents represents a fast form of desensitization. We show that both mechanisms of desensitization influence each other. S892 phosphorylation slows KCTD12-induced K+ current desensitization by rearranging KCTD12 at the receptor. In turn, KCTD12 promotes tonic S892 phosphorylation by binding to GABAB receptors. This cross-regulation renders the signaling of GABAB receptors more precise and highly dependent on both the expression of KCTD12 and the activity of PKA. (Adelfinger et al., 2014)
The third part reveals that all KCTDs exert marginal allosteric influence on the ligand binding affinity of GABAB receptors. However, we show that KCTD8, in contrast to KCTD12 and KCTD16, reduces the basal G-protein activation of GABAB receptors. (Rajalu et al., 2014)
The fourth part summarizes an ongoing project in which we investigate the effects of 14-3-3 proteins and cullin3 (CUL3) on GABAB receptor signaling. 14-3-3 e and ? specifically interact with KCTD16 through its H2-domain. This binding regulates the expression of KCTD16 and GABAB2 resulting in altered Ga-signaling of GABAB receptors. Furthermore, we report a specific interaction between KCTD16 and CUL3, which is controlled by 14-3-3 proteins. In summary, we propose that 14-3-3 proteins determine the rate of lysosomal GABAB receptor degradation, which is induced upon binding of KCTD16 and CUL3. (Adelfinger et al., in preparation)
Finally, in collaboration with the group of Jan Siemens from Heidelberg we studied how GABAB receptors reciprocally counteract the sensitization of the capsaicin receptor TRPV1. (Hanack et al., in preparation)
|Committee Members:||Scheiffele, Peter|
|Faculties and Departments:||03 Faculty of Medicine > Departement Biomedizin > Division of Physiology > Molecular Neurobiology Synaptic Plasticity (Bettler)|
|Bibsysno:||Link to catalogue|
|Number of Pages:||1 Vol.|
|Last Modified:||30 Jun 2016 10:56|
|Deposited On:||13 Jan 2015 15:40|
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