P6: Does cGKI – through BK channels in the nuclear envelope – counteract activity-dependent acquired neuroprotection? (until 31.12.2023)
Aims
To define the role of cGKI-driven BK channels in the nuclear envelope of hippocampal neurons as regulators of nucleoplasmic [Ca2+] and transcriptional activity.
Questions and Methods
cGKI and Neuroprotection
- Use isolated nuclei for biochemical characterization of nuclear cGKI and BK channel isoforms as well as for determining the molecular interactions between the two proteins.
- Employ voltage and Ca2+-sensitive dyes in isolated nuclei and nuclei of cultured hippocampal neurons from wild-type as well as BK channel-/- and cGKI-/- mice to validate BK channel and cGKI functions.
- In parallel, we will develop electrophysiological tools to observe cGKI-mediated modulation of nuclear BK channel currents directly and to distinguish between BK channels in the inner or outer leaflet of the nuclear envelope (excised patch).
- Nuclear Ca2+ and voltage will be observed in the presence or absence of pharmacological modulators of cGKI and BK channels. BK channel and downstream transcription factors like CREB will be isolated from nuclear fractions for biochemical analysis of phosphorylation by cGKI. cGKI and BK channel constructs will be transfected into neuronal cultures from cGKI-/- and BK channel-/- mice, respectively, as part of a molecular replacement strategy.
- Further, we will test how the putative regulation of BK channels by cGKI influences activity-dependent acquired neuroprotection of cultured hippocampal neurons in development, long-term survival, and ischemic cell death.
Boston Internship
Roberts Lab
During the visit of the Roberts lab in Boston, the students will profit from its immense experience in examining nuclear cGKI function. This includes using
- wide-field imaging and statistical modeling to localize proteins within sub-cellular compartments, such as the nucleus and endomembrane system, and
- nuclear cGKI-regulated control of signaling using a genetically-encoded nuclear phospho-CREB biosensor probe and molecular imaging techniques.
Boston Co-mentor
Assoc. Prof. Jesse D. Roberts, MD
Link to Boston researcher lab
Doctoral Students
Thomas Pham (graduated in January 2024)
Thomas Pham studied Pharmacy at the University of Tübingen and earned his approbation as a pharmacist in 2017. After his practical year in a pharmacy and pharmaceutical industry, he decided to discover the field of research, and therefore completed his Master's degree in Pharmaceutical Sciences and Technologies in the Lukowski Lab with a focus on the CNS. His interest in cellular signaling pathways inspired him to do his doctoral studies as part of the GRK 2381, where he investigates in the group of Peter Ruth the interaction of the BK channel and the cGMP signaling pathway in the nucleus to evaluate its impact on neuroprotection.
Tamara Hussein
Tamara studied Biochemistry at the Goethe-University of Frankfurt, Germany. During her Bachelor´s thesis at the Max-Planck Institute for Biophysics, she focused on the determination of open- and closed states of Channelrhodopsin-2 using electrophysiological measurements especially. Subsequently, she completed her master's degree in biochemistry in Frankfurt with a focus on biochemical physics. Tamara did her master´s thesis at the Institute for Pharmacology and Clinical Pharmacy in Frankfurt, where she worked on the function of HCN3 ion channels in somatosensory processing. There, she broadened her knowledge on neuroscience and decided to continue as a PhD student in the laboratory of Peter Ruth in Tübingen. As part of the GRK 2381, she aims to define the role of cGKI- driven BK channels in the nuclear envelope of hippocampal neurons and its impact on neuroprotection.
Key Publications
Föller M, Jaumann M, Dettling J, Saxena A, Pakladok T, Munoz C, Ruth P, Sopjani M, Seebohm G, Rüttiger L, Knipper M, Lang F. AMP-activated protein kinase in BK-channel regulation and protection against hearing loss following acoustic overstimulation. FASEB J. 2012;26:4243-53
Frankenreiter S, Bednarczyk P, Kniess A, Bork N, Straubinger J, Koprowski P, Wrzosek A, Mohr E, Logan A, Murphy MP, Gawaz M, Krieg T, Szewczyk A, Nikolaev VO, Ruth P, Lukowski R. cGMP-elevating compounds and ischemic conditioning provide cardioprotection against ischemia and reperfusion injury via cardiomyocyte-specific BK channels. Circulation. 2017;doi: 10.1161/CIRCULATIONAHA.117.028723