Universität zu Köln

Gao, Jie (2015). Elucidating the molecular function of CLUH in mammalian system. PhD thesis, Universität zu Köln.

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Abstract

The mitochondrial proteome is composed of both mitochondrial and nuclear encoded proteins. Restructuration of mitochondrial proteome is often required upon on change in nutrient availabilities and stress conditions. To facilitate this process, the nuclear and mitochondrial genome must coordinate their protein expression in a well-concerted manner. Additional factors are present to mediate the coordination. These factors are diverse in function ranging from energy sensing to translation of the specific nuclear encoded mitochondrial proteins. Clu is a well-conserved cytosolic protein, however its molecular function remains unknown. A small fraction of Clu is observed outside of mitochondria in Drosophila. Clu mutant of multicellular organisms display phenotypes of growth defect, failure to respond to stress and early death. However these phenotypes are absent from single cellular organisms. Nevertheless, all Clu mutants have clustered mitochondria and this leads to the speculation that CLUH and mitochondria are functionally closely related. In this study, we analysed the genes that coregulate with human and murine CLUH/Cluh, respectively, and identified two main clusters of genes: nuclear encoded mitochondrial genes and cytosolic translation related genes. After this, we identified the molecular function of human CLUH as an mRNA binding protein by using crosslinking immunoprecipitation (CLIP). By comparing the mRNAs enriched by CLUH to control IgG, we discovered that CLUH binds specifically to mRNAs of nuclear encoded mitochondrial proteins (NEMP). Among the mRNAs bound by CLUH, we found enrichments for genes involved in branched-chain amino acid degradation, mitochondrial dysfunction, TCA cycle, oxidative phosphorylation and fatty acid α-oxidation. Subsequently, we showed that CLUH is a positive translation regulator of its target mRNAs, because in the absence of CLUH, translation of its target mRNAs appeared to be reduced. However, general translation was not affected in the absence of CLUH. Furthermore, we found a reduction of CLUH in PGC-1α null mouse embryonic fibroblasts (MEFs), which indicates that CLUH expression might be under the transcriptional control of PGC-1α. Together, we conclude that CLUH might be important for the biogenesis of its target proteins under influence of cellular metabolism.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Gao, Jie gaojie84@hotmail.com UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-61216
Date:	4 May 2015
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Biology > Institute for Genetics
Subjects:	Life sciences
Uncontrolled Keywords:	Keywords Language CLUH English Mitochondria English Nuclear encoded mitochondrial proteins English RNA binding protein English
Date of oral exam:	4 May 2015
Referee:	Name Academic Title Rugarli, Elena Prof. Dr. Trifunovic, Aleksandra Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/6121