Universität zu Köln

Artoni, Filippo ORCID: 0000-0003-3902-9217 (2024). Nutritional and pharmacological modes of mTOR inhibition. PhD thesis, Universität zu Köln.

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Abstract

mTOR signaling is a crucial pathway involved in numerous biological and disease processes. Hyperactive mTOR signaling has been linked to several diseases including cancer, diabetes, metabolic and neurological syndromes as well as the aging process. Inhibition of mTOR signaling is an important experimental and therapeutic tool to study mTOR biology and treat medical conditions involving hyperactive mTOR signaling. Several modes of mTOR inhibition exist including pharmacological inhibitors such as rapamycin and Torin1 as well as other interventions like amino acid (AA) starvation and genetic deletion of mTOR regulators. Despite the wide use of these interventions, a comprehensive understanding of the differential effects elicited by different modes of mTOR inhibition on cellular physiology is still lacking. Moreover, researchers outside the mTOR field tend to use these interventions interchangeably to probe a variety of biological questions, which can lead to incomplete or erroneous findings. Here, to comprehensively study the differences between different modes of mTOR inhibition, we measured the effects that four interventions (rapamycin, Torin1, AA starvation and loss of RagA/B GTPases) elicited on the cellular proteome via a combination of proteomics and systems biology approaches. Our findings reveal that different modes of mTOR inhibition, while sharing a common set of protein targets, lead to unique proteomic signatures. Specifically, we find that Torin1 regulates mRNA splicing and lipogenesis-related proteins to a much greater extent than rapamycin. Additionally, we show how modeling AA starvation with Torin1 treatment may lead to inaccurate results, especially when studying AA-induced transcriptional responses. Moreover, we show that, while rapamycin, Torin1 and AA starvation are all associated with an increase in oxidative-related stress proteins, differential regulation of mitochondrial proteins suggests that different modes of mTOR inhibition induce ROS production via distinct mechanisms. Furthermore, we show how loss of RagA/B is characterized by a unique enrichment of lysosomal and cytoskeletal proteins, while also influencing a subset of the responses to AA starvation. Finally, an expansion of this study shows that rapamycin’s effects on both the cellular transcriptome and proteome are exclusively mediated via mTOR inhibition. Ultimately, these findings expand our knowledge of different modes of mTOR inhibition, while also providing ample material for the generation of novel hypotheses in the mTOR biology field. Ultimately, this study will also enable researchers interested in studying mTOR- related processes to select the most appropriate mode of mTOR inhibition depending on their specific biological question.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Artoni, Filippo artonifil@gmail.com orcid.org/0000-0003-3902-9217 UNSPECIFIED
Contributors:	Contribution Name Email Reviewer Demetriades, Constantinos demetriades@age.mpg.de Reviewer Lemberg, Marius m.lemberg@uni-koeln.de
URN:	urn:nbn:de:hbz:38-726511
Date:	2024
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Außeruniversitäre Forschungseinrichtungen > MPI for Biology of Ageing
Subjects:	Natural sciences and mathematics Life sciences
Uncontrolled Keywords:	Keywords Language mtor rapamycin torin starvation proteomics English
Date of oral exam:	6 December 2023
Referee:	Name Academic Title Demetriades, Constantinos Dr. Lemberg, Marius Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/72651