Dokument: Role of MICOS-dependent cristae membrane dynamics within mitochondria
| Titel: | Role of MICOS-dependent cristae membrane dynamics within mitochondria | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=66176 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20240619-105633-4 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Golombek, Mathias [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Reichert, Andreas [Gutachter] Prof. Dr. Weber, Andreas [Gutachter] | |||||||
| Stichwörter: | Mitochondrien, MICOS, Cristae | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 570 Biowissenschaften; Biologie | |||||||
| Beschreibung: | Over the past decades the representation of mitochondria in many textbooks has changed from being presented as a small bean-shaped organelle with the main function to provide energy in the form of ATP to an organelle that form a vast and highly dynamic network throughout the cell and is involved in numerous metabolic and regulatory processes. More recently, several working groups could show that the inside of the organelle is even more in motion than the overall network. If the fine ultra-structure of the IMM is correctly established, cristae membranes undergo continues cycles of membrane merging and splitting in a time scale of less than a single second. MICOS has been established as a key player for cristae dynamics, as the initial formation of crista is required for their fission and fusion. Different types of IMM fission and fusion are described in the crista fission and fusion (CriFF) model. Despite some proposed functions of CriFF like a regulatory role of intramitochondrial quality control, the direct functions of IMM remodelling remain unknown. Several questions remain unanswered, as it is unknown what molecular players are involved in the maintenance of cristae dynamics or what bioenergetically requirements must be fulfilled to keep the membranes in motion. It is not known if this process is of a passive nature or an active process that requires a continuous hydrolysis of ATP. This thesis aimed to answer some of these open questions by inhibition of some key proteins of mitochondrial energy production and associated features of functional mitochondria. We utilized state-of-the-art super-resolution live-cell imaging with a highly detailed image analysis. Our studies provided reliable data showing that inhibition of individual OXPHOS complexes and a depletion of the mitochondrial membrane potential (∆Ψm) did not inhibit IMM merging and splitting, while altering the mitochondrial ultrastructure. Furthermore, we could show that cristae remodelling can occur despite heavily reduced mitochondrial ATP levels and provide prove that maintenance of the ∆Ψm is not required for IMM remodelling.
Additionally, we examined the role of adenine nucleotide translocator (ANT) in the context of cristae remodelling. In doing so we used the ANT inhibitor bongkrekic acid (BKA). This compound locks the ANTs in the m-state and prevents any further exchange of ADP and ATP. With the applied concentration of about 50 µM we observed a drastic reduction in respiration of HeLa WT cells after 30 min. With live-cell STED super-resolution imaging we observed a strong increase of mitochondria with aberrant in crista structure compared to the control group and confirmed these observations with electron microscopy. Treatment with 50 µM BKA over a period also revealed a significant reduction of ∆Ψm, less drastic than a total membrane uncoupling with CCCP, though. Of high interest are the results of ANT inhibition in the background of cristae dynamics. The ADP/ATP translocases have not been associated with cristae dynamics so far, we on the other hand could demonstrate that rates of crista merging and splitting events are significantly reduced upon BKA treatment in a subset of mitochondria with aberrant crista structure. Furthermore, some results obtained in this doctoral thesis linked the regulatory role of the apolipoproteins MIC26 and MIC27 to formation of OXPHOS complexes via regulation of cardiolipin levels. It was shown that loss of both apolipoproteins results in drastic changes of mitochondrial morphology, reduced respiration, changes in cardiolipin levels and perturbed OXPHOS complex assembly. These drastic reductions were rescued by stable expression of the MIC26 and MIC27 in combination and by expression of CRLS1. Although the main focus of this doctoral thesis is the investigation of the physiological role, relevance and regulation of MICOS-dependent cristae remodelling I contributed to a project that focused a therapeutic treatment of the invasive squamous cell carcinoma cell line SCL-1 with the naturally occurring polyphenolic aldehyde (±) gossypol. Gossypol has a selective cytotoxicity on SCL-1 cells. This toxicity is induced by mitochondrial dysfunction, causing necroptotic cell death. These results indicate a high potential for gossypol as an alternative anticancer drug for the treatment of cutaneous squamous cell carcinoma. In summary, we showed that IMM remodelling takes place in metabolically compromised mitochondria, even after significant reduction of mitochondrial ATP levels or depletion of ∆Ψm and proposing ANTs as a possible regulator of IMM architecture and dynamics. Furthermore, proposing a connection between membrane architecture and function, with as mitochondria with highly perturbed IMM morphology featured a reduction in membrane merging and splitting. | |||||||
| Lizenz: |  Dieses Werk ist lizenziert unter einer Creative Commons Namensnennung 4.0 International Lizenz | |||||||
| Fachbereich / Einrichtung: | Medizinische Fakultät » Institute » Institut für Biochemie und Molekularbiologie I | |||||||
| Dokument erstellt am: | 19.06.2024 | |||||||
| Dateien geändert am: | 19.06.2024 | |||||||
| Promotionsantrag am: | 08.03.2024 | |||||||
| Datum der Promotion: | 11.06.2024 |
