Peroxisomal calcium handling and homeostasis
von Yelena Sargsyan
Datum der mündl. Prüfung:2022-01-21
Erschienen:2022-04-26
Betreuer:Prof. Dr. Sven Thoms
Gutachter:Prof. Dr. Sven Thoms
Gutachter:Prof. Dr. Silvio Rizzoli
Dateien
Name:Dissertation_SargsyanYelena_05.03.2022.pdf
Size:5.03Mb
Format:PDF
Description:Dissertation
Diese Datei ist bis 20.01.2024 gesperrt.
Zusammenfassung
Englisch
Peroxisomes are ubiquitous cellular organelles in eukaryotes essential for metabolism. The close localization of peroxisomes with the sarcoplasmic reticulum and T-tubules is known from electron micrographs of rodent hearts. This association of peroxisomes with sites of excitation-contraction coupling suggests a peroxisomal role in calcium handling. However, there is little known about peroxisomal calcium and previous studies brought up extensive contradictions. This work addresses peroxisomal Ca2+ handling in non-excitable HeLa cells, and in excitable cells represented by cardiomyocytes. Using both models, it is demonstrated that peroxisomal Ca2+ rises in dependance of cytosolic Ca2+ from a steady state of 600 nM to 2.4 µM. It is also shown that over 80% of peroxisomes in cardiomyocytes are in contact with ryanodine receptors and that cardiac peroxisomes take up Ca2+ when intracellular Ca2+ stores are depleted. These results suggest that peroxisomes in cardiomyocytes may contribute to an effective excitation-contraction process. Further, we studied the mechanisms of Ca2+ entry to peroxisomes. Taken together, this work provides the first evidence of peroxisomal Ca2+ handling taking place in cardiomyocytes and that several mechanisms to interact with it exist. Modulation of peroxisomal Ca2+ homeostasis may have future clinical application in cases of impaired cellular Ca2+ handling, such as certain types of arrhythmias.
Keywords: peroxisomes, calcium