Universität zu Köln

Hofsetz, Eduard (2019). The role of SDHA in the tissue-specific regulation of metabolism and proteomic approaches to identify novel ClpXP substrates. PhD thesis, Universität zu Köln.

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Abstract

After Theodor Schwann formulated the first cell theory in 1839, another 60 years of histological advances passed by before mitochondria were discovered and the name was phrased. Yet, 120 years later, many aspects of mitochondrial biology remain enigmatic and mitochondria emerged as fundamental organelles of almost all eukaryotes far beyond the role as the powerhouses of the cell. To contribute to the continuously growing understanding of these multifaceted organelles, the roles of succinate dehydrogenase subunit A (SDHA) and ATP-dependent Clp protease (ClpXP) in mitochondrial metabolism and proteostasis, respectively, were investigated in vivo and in vitro. Conditional knockout of SDHA in the heart and striated muscles caused isolated complex II deficiency and ultimately organ failure. However, metabolic differences of these tissues result in varying adaptations and stress responses. This finding emphasizes the significance of the metabolic background, even if the primary defect is ATP depletion. This is particularly important for the treatment of malignant cells with SDH mutations, as the affected cell types can differ in terms of metabolic adaptations. In order to understand the role of ClpXP in mitochondrial proteostasis, diverse proteomic approaches were employed to identify novel ClpXP targets as well as to address the mode of degradation and potentially tissue-specific activity. The combination of a classical in vitro substrate screen and the recently developed N-terminome quantification identified or confirmed several bona fide ClpXP substrates and a clear preference for arginine at the P1 position of the cleavage site. Furthermore, the development of an in vivo model for the conditional expression of CLPP in mouse hearts provided the proof of principle for tissue specific substrate screens and confirmed CLPX as the rate-limiting subunit in vivo.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Hofsetz, Eduard ehofsetz@web.de UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-104932
Date:	26 September 2019
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	CECAD - Cluster of Excellence Cellular Stress Responses in Aging-Associated Diseases
Subjects:	Life sciences
Uncontrolled Keywords:	Keywords Language CLPP English SDHA English Metabolism English
Date of oral exam:	29 November 2019
Referee:	Name Academic Title Trifunovic, Aleksandra Prof. Dr. Langer, Thomas Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/10493