1. Structural determinants for activation of the Tau kinase CDK5 by the serotonin receptor 5-HT7R
- Author
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Jana Ackmann, Alina Brüge, Lizaveta Gotina, Sungsu Lim, Kathrin Jahreis, Anna-Lena Vollbrecht, Yun Kyung Kim, Ae Nim Pae, Josephine Labus, and Evgeni Ponimaskin
- Subjects
Serotonin receptor 7 (5-HT7R) ,Cyclin‐dependent kinase 5 (CDK5) ,Tau protein (Tau) and tauopathy ,Site-directed mutagenesis ,Computational modeling ,Protein–protein complex ,Medicine ,Cytology ,QH573-671 - Abstract
Abstract Background Multiple neurodegenerative diseases are induced by the formation and deposition of protein aggregates. In particular, the microtubule-associated protein Tau leads to the development of so-called tauopathies characterized by the aggregation of hyperphosphorylated Tau within neurons. We recently showed that the constitutive activity of the serotonin receptor 7 (5-HT7R) is required for Tau hyperphosphorylation and aggregation through activation of the cyclin-dependent kinase 5 (CDK5). We also demonstrated physical interaction between 5-HT7R and CDK5 at the plasma membrane suggesting that the 5-HT7R/CDK5 complex is an integral part of the signaling network involved in Tau-mediated pathology. Methods Using biochemical, microscopic, molecular biological, computational and AI-based approaches, we investigated structural requirements for the formation of 5-HT7R/CDK5 complex. Results We demonstrated that 5-HT7R domains responsible for coupling to Gs proteins are not involved in receptor interaction with CDK5. We also created a structural model of the 5-HT7R/CDK5 complex and refined the interaction interface. The model predicted two conserved phenylalanine residues, F278 and F281, within the third intracellular loop of 5-HT7R to be potentially important for complex formation. While site-directed mutagenesis of these residues did not influence Gs protein-mediated receptor signaling, replacement of both phenylalanines by alanine residues significantly reduced 5-HT7R/CDK5 interaction and receptor-mediated CDK5 activation, leading to reduced Tau hyperphosphorylation and aggregation. Molecular dynamics simulations of 5-HT7R/CDK5 complex for wild-type and receptor mutants confirmed binding interface stability of the initial model. Conclusions Our results provide a structural basis for the development of novel drugs targeting the 5-HT7R/CDK5 interaction interface for the selective treatment of Tau-related disorders, including frontotemporal dementia and Alzheimer’s disease.
- Published
- 2024
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