Dokument: Regulatory Protein-Protein Interactions within the PER Complex of the Circadian Clock
| Titel: | Regulatory Protein-Protein Interactions within the PER Complex of the Circadian Clock | |||||||
| Weiterer Titel: | Regulation der Protein-Protein-Interaktionen im PER-Komplex der zirkadianen Uhr | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=67946 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20241216-133423-3 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Ibrahim, Hussam [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Reinke, Hans [Gutachter] Prof. Dr. Björn Stork [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 600 Technik, Medizin, angewandte Wissenschaften » 610 Medizin und Gesundheit | |||||||
| Beschreibung: | The molecular mechanism of the circadian clock is governed by a transcription-translation feedback loop, involving the interaction of numerous clock genes and proteins including PERIODs (PERs) and CRYPTOCHROMEs (CRYs). PER2 is a transcriptional repressor that plays a critical role in regulating the circadian clock as well as in a diverse array of physiological processes, encompassing DNA damage response, metabolism, and immunity. Recent research has suggested that PER2 has non-transcriptional roles in addition to its well-known function in transcriptional regulation of the circadian clock. For instance, studies have shown that downregulation of PER2 reduces levels of autophagy, a predominantly posttranslationally regulated cytoplasmic process. Additionally, PER2 has been found to act as a scaffold for tethering Tuberous sclerosis 1 (TSC1) and Mammalian target of rapamycin (mTOR) together, thereby suppressing liver mammalian target of rapamycin complex 1 (mTORC1) activity during fasting, which further supports its cytoplasmic role. These findings suggest that PER2 has a diverse range of functions beyond its role in transcriptional regulation of the circadian clock and highlight the importance of further research into its non-transcriptional functions.
This work aimed at characterizing potential cytoplasmic PER2 binding proteins in order to shed more light on its non-transcriptional functions. First, a biochemical screen for interacting proteins was conducted, identifying among other proteins GTPase Activating Protein and VPS9 Domains 1 (GAPVD1) as a strong binding partner of PER2. GAPVD1 functions both as a GTPase-activating protein (GAP) for the small GTPase RAS and as a guanine nucleotide exchange factor (GEF) for the Ras-related proteins RAB5A and RAB31. GAPVD1 is involved in diverse biological processes such as endocytosis, epidermal growth factor receptor (EGFR) trafficking and degradation, and insulin receptor internalization. The mutual functional relationship between PER2 and GAPVD1 has been extensively studied in my thesis. CSNK1D is a kinase that plays a fundamental role for the function of the PER complex. Investigation of GAPVD1 phosphorylation revealed its regulation by CSNK1D and PER proteins, with seven mapped phosphorylation sites in its central domain, thus highlighting a cytoplasmc role of PER2 in modulating phosphorylation levels of interacting proteins. Furthermore, my results show that GAPVD1 is rhythmically phosphorylated with a timely correlation to its association with the PER complex, and that GAPVD1 modulates PER2-CSNK1D binding, indicating its importance for the CSNK1D-dependent PER2 phosphoswitch within the PER complex. Finally, the binding domains in GAPVD1 responsible for PER2 and CSNK1D binding were investigated. The domains Helix 2 and Bottom helix (H2B), which the Alphafold algorithm predicts to be highly structured domains in GAPVD1, bind to PER2 and CSNK1D. Moreover, the results also indicate that GAPVD1 might contain additional domains that bind PER2 and CSNK1D, which might be located in the Intrinsically Disordered Region (IDR). Finally, my findings also reveal a predominantly inhibitory role of the VPS9 domain of GAPVD1 in regulating the binding of PER2 but not CSNK1D to GAPVD1. Taken together, these findings provide novel insights into the molecular mechanisms that GAPVD1 employs for regulation of PER complex function within the molecular circadian oscillator. Overall, this thesis provides new perspectives on the regulation of the PER complex by GAPVD1 and thereby suggests potential avenues for therapeutic interventions to enhance personal health and well-being in relation to circadian rhythmicity. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Medizinische Fakultät | |||||||
| Dokument erstellt am: | 16.12.2024 | |||||||
| Dateien geändert am: | 16.12.2024 | |||||||
| Promotionsantrag am: | 16.07.2024 | |||||||
| Datum der Promotion: | 03.12.2024 |
