|Titel:||The functional role of the cell adhesion molecule L1: characterization of L1/687 and L1/858-863 transgenic mice||Sprache:||Englisch||Autor*in:||Granato, Viviana||GND-Schlagwörter:||L1
cell adhesion molecule
|Erscheinungsdatum:||2022||Tag der mündlichen Prüfung:||2023-02-13||Zusammenfassung:||
The cell adhesion molecule L1 has a key role during the development of the nervous system and is involved in different neuronal processes such as migration, adhesion, cell proliferation, neuritogenesis, synapse formation, and synaptic plasticity. Based on a previous work that showed the translocation of a fragment of L1, L1-70, into mitochondria, I showed in this thesis through flow cytometry that L1-70 is present on the surface of mitochondria and that interacts with different proteins involved in the mitophagy/mitochondrial quality control process. The interaction between L1 and mitophagy markers as LC3 and Parkin has been confirmed in vitro using proximity ligation assay on cerebellar granule cells, ELISA, and co-immunoprecipitation assays. Moreover, I showed an alteration in the levels of another mitophagy protein, BNIP3, in L1-deficient mice. To further determine the role of L1-70 in mitochondrial pathways, I used in this thesis two transgenic mice lines, expressing full-length L1, but no L1-70. To confirm the absence of L1-70 in the transgenic mice line, L1/687 and L1/858-863, proximity ligation assay was performed. The outcome of the experiment confirmed that the interaction of L1 with LC3 was due to the L1-70 fragment. Levels of LC3 were also detected by western blot on isolated mitochondria from L1/687 and L1/858-863, showing an alteration of the protein levels, but not its production. To understand the role of L1-70 in mitochondrial processes, different assays were performed. I showed that in cultured cerebellar neurons lacking L1-70 fragment, mitochondria move more retrogradely, exhibit reduced mitochondrial membrane potential and had lower ATP levels compared to wild-type littermates. These results suggest that L1-70 is important for mitochondrial homeostasis and its absence reflects on the mitochondrial quality and stability.
In addition, with staining of coronal brain sections from L1/858- 863 and L1/687, I showed that L1/858-863 brains, had diffuse cells and higher hippocampal area. The role of the L1-70 fragment was further analyzed with behavioral experiments in order to characterize L1/687 phenotype. Through open field, elevated plus maze, and marble burying test I showed that L1/687 mice did not display anxiety-like behavior compared to wild-type mice, but higher locomotor activity, expressed by the higher distance traveled in the arena. Besides, with the home cage activity test, I showed that L1/687 mice had a normal circadian rhythm, with L1/687 female mice being slightly more active compared to their wild-type littermates. In addition, with the social interaction test, I showed no alteration in the social behavior of transgenic mice that exhibited unaltered social memory and predilection for novel experiences. The use of motor tests as rotarod, beam walking and pole test highlighted that there was no physical impairment in L1/687 mice. Using the pole test and the beam walking, no differences were detected, suggesting that the absence of L1-70 does not lead to impairment in motor coordination, but more likely to a possible impairment in the learning circuit. Altogether, the new findings of this study could help reveals new aspects about the role and the importance of L1 and the L1-70 fragment in the murine central nervous system. L1-70 has in fact a role in mitochondrial dynamics and a possible function in mitochondrial quality control. These findings can be relevant in further understanding neurodegenerative diseases associated with mitochondrial impairments.
|Enthalten in den Sammlungen:||Elektronische Dissertationen und Habilitationen|
Dateien zu dieser Ressource:
|Dissertation Granato Viviana, 7231095.pdf||9ea1619eb532beafd60297e927a754ff||7.51 MB||Adobe PDF||Öffnen/Anzeigen|
geprüft am 31.03.2023
geprüft am 31.03.2023