Calciumtransienten in Peroxisomen

Bickmeyer, Uta

dc.contributor.advisor	Thoms, Sven Prof. Dr.
dc.contributor.author	Bickmeyer, Uta
dc.date.accessioned	2024-11-12T16:49:55Z
dc.date.available	2025-01-06T00:50:12Z
dc.date.issued	2024-11-12
dc.identifier.uri	http://resolver.sub.uni-goettingen.de/purl?ediss-11858/15601
dc.identifier.uri	http://dx.doi.org/10.53846/goediss-10842
dc.format.extent	102	de
dc.language.iso	deu	de
dc.rights.uri	http://creativecommons.org/licenses/by/4.0/
dc.subject.ddc	610	de
dc.title	Calciumtransienten in Peroxisomen	de
dc.type	doctoralThesis	de
dc.contributor.referee	Thoms, Sven Prof. Dr.
dc.date.examination	2024-12-09	de
dc.description.abstracteng	Introduction: Peroxisomes are small cell organelles that play an important role in metabolic functions such as alpha- and beta-oxidation of fatty acids and ROS-homeostasis. So far the data of calcium concentrations and function in Peroxisomes is inconsistent. The function of peroxisomes in the heart is still under ongoing investigation. Peroxisomes are described to potentially have cardioprotective functions as peroxisomal diseases e.g. the adult Refsum-Syndrom lead to cardiomyopathy, arrhythmias and eventually heart failure. They occur in high numbers in the myocard especially in the left ventricle where there is an especially high energy demand. As a result of functional translational readthrough the Malate-Dehydrogenase is localized in peroxisomes. So as oxidation of fatty acids occur in peroxisomes a malate shuttle equivalent to the one in mitochondria is assumed to also play a role in peroxisomal regeneration of reducing equivalents. The aspartate/glutamate carriers 1 and 2 (AGC1 and 2) as part of the malate shuttle have calcium-binding EF-hands localised in their N-terminal domains. The thesis focuses on measuring peroxisomal calcium transients in cardiomyocytes as well as investigating the topology of AGC1 and 2 in the peroxisomal membrane as potential targets of calcium signalling. Methods: Cloned FRET-sensors localised in peroxisomes and the peroxisomal membrane with extraluminal orientation were transfected in Hela and HEK293 cells. Live-cell imaging was performed and the cells were stimulated chemically with histamine or treated with ionomycin to evoke an intracellular rise of calcium ion concentrations. To measure calcium transients in cardiac peroxisomes iPSC cardiomyocytes and neonatal rat cardiomyocytes were used. These cells were stimulated with SERCA-Inhibitor thapsigargin as well as electrical stimulation. Furthermore a modified form of Fluorescence Protein Protection Assay was used to investigate the topology of peroxisomal AGC1 and 2. Here permeabilising the cells with digitonin and treating them with Proteinase K was combined with immunofluorescence. Results: It was shown that calcium ions can enter peroxisomes in non-electric cells as well as in cardiomyocytes. In both iPSC and neonatal rat cardiomyocytes peroxisomal calcium concentrations increased after chemical stimulation with thapsigargin. Neonatal rat cardiomyocytes showed rhythmic calcium transients under electrical stimulation on a beat to beat basis. With immunofluorescence peroxisomal localisation of AGC1 and partly AGC2 was shown. The Fluorescence Protein protection Assay provided hints for an intraluminal peroxisomal localisation of the calcium-binding EF-hands thus identifying a potential target for calcium signalling. Discussion: The advantage of FRET-sensors is the high spatial resolution especially for measuring small organelles like peroxisomes. A limiting factor might have been the lower time resolution due to conformational changes that the FRET-Sensor needs to undergo after calcium binding. Calcium can enter cardiac peroxisomes in case of neonatal rat cardiomyocytes even on a beat-to-beat basis which hints that peroxisomal functions might be regulated through calcium signals. With the likely peroxisomal localisation of AGC1 and 2 potential targets of calcium signalling could be found.	de
dc.contributor.coReferee	Brandenburg, Sören PD Dr.
dc.contributor.thirdReferee	Kube, Dieter Prof. Dr.
dc.subject.ger	Peroxisomen	de
dc.subject.ger	Calciummessungen	de
dc.subject.ger	FRET-Sensor	de
dc.subject.ger	Aspartat/Glutatamat Carrier	de
dc.subject.ger	Kardiomyozyten	de
dc.subject.eng	Calcium imaging	de
dc.subject.eng	Peroxisomes	de
dc.subject.eng	Aspartate/Glutamate Carrier	de
dc.subject.eng	cardiomyocytes	de
dc.subject.eng	GECI	de
dc.identifier.urn	urn:nbn:de:gbv:7-ediss-15601-0
dc.affiliation.institute	Medizinische Fakultät	de
dc.subject.gokfull	Pädiatrie / Neonatologie / Kinderchirurgie - Allgemein- und Gesamtdarstellungen (PPN619876093)	de
dc.subject.gokfull	Innere Medizin - Allgemein- und Gesamtdarstellungen (PPN619875747)	de
dc.subject.gokfull	Physiologie / Pathophysiologie - Allgemein- und Gesamtdarstellungen (PPN619875283)	de
dc.description.embargoed	2025-01-06	de
dc.identifier.ppn	1908360879
dc.notes.confirmationsent	Confirmation sent 2024-11-12T19:45:01	de

Files in this item

Name:Bickmeyer_Uta_Dissertation 12_24_Änderung.pdf

Size:4.756Mb

Format:PDF

View/Open

Name:: Bickmeyer_Uta_Dissertation ...
Size:: 4.756Mb
Format:: PDF

View/Open

This item appears in the following Collection(s)

Human- und Zahnmedizin [3110]

Show simple item record