Universität zu Köln

Hinterding, Helena Maria (2022). The MAPK/ERK signalling pathway: functional characterisation of rare human genetic variants associated with longevity. PhD thesis, Universität zu Köln.

PDF Helena Hinterding_PhD_Thesis_2022_pub.pdf - Published Version Download (10MB)

Abstract

Observational and experimental studies have revealed that ageing is malleable. Research in different organisms has shown that dietary, pharmacological and genetic interventions can extend health- and lifespan. Similarly in humans, diet and other lifestyle factors such as exercise, have been shown to slow the ageing process, however, the role of genetics is less clear. For human lifespan, the heritability is somewhere in the range of 12-25%, but for longevity, i.e. belonging to the top 10% longest-lived, the heritability remains elusive. Investigations in this field have, thus far, identified a limited number of common longevity-associated variants, suggesting that rare genetic variants may play a role in human longevity. Ageing research in model organisms has implicated the insulin/insulin-like growth factor signalling (IIS) network in lifespan and longevity. A mild reduction in activity through genetic and pharmacological interventions in the IIS network, e.g. with rapamycin, have been shown to robustly extend lifespan. The mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signalling pathway is one branch of the IIS network and has been implicated in lifespan in yeast, worms, flies and mice, through its genetic and pharmacological manipulation, e.g. with trametinib. Whether it also plays a role in human lifespan and longevity, remains unknown. My PhD thesis first explores the role of rare genetic variants in the MAPK/ERK signalling pathway observed in long-lived individuals belonging to the Leiden Longevity Study. After their identification using a bioinformatic pipeline, I aimed to functionally characterise these genetic variants in vitro and in vivo to determine their possible role in human longevity. Second, I investigated the geroprotective potential of a dual MAPK/ERK and PI3K/AKT/mTOR signalling pathway inhibitor, Rigosertib, in promoting healthy ageing in the fruit fly. Chapter 3 of this thesis entails a novel pipeline to functionally characterise genetic variants in cells and different model organisms. For this purpose, I generated cells, flies and mice harbouring longevity-associated human variants and assessed their effect on cellular phenotypes, such as pathway activity and stress resistance. Two variants, Nf1Phe1112Leu and Raf1Asp633Tyr, showed opposing effects on MAPK/ERK signalling pathway activity and resulted in extensive rewiring of the MAPK/ERK related proteome and metabolome in cells. The one variant that I introduced in the fly, Nf1Phe1148Leu, led to shortened lifespan in the homozygous state, while it did not seem to affect lifespan in flies in the heterozygous state (in which it was detected in the long-lived individuals). For the other variant, however, Raf1Asp633Tyr, I was able to show an improved stress response, which was conserved in mouse embryonic fibroblasts, suggesting that this variant may have contributed to human longevity through improved stress resistance mechanisms. In Chapter 4 of this thesis, I investigated the effects of Rigosertib treatment on health- and lifespan in the fruit fly. I could show that Rigosertib robustly extends lifespan in female and male flies. Somewhat surprisingly, the MAPK/ERK signalling pathway activity appeared downregulated in vitro and upregulated in vivo, highlighting context specific regulation of this signalling pathway. Furthermore, in order to understand how the drug extends lifespan in both sexes, I investigated gut health of Rigosertib-fed flies. I could demonstrate that Rigosertib treatment ameliorated age-related decline in gut homeostasis, suggesting that this at least partially contributes to improved health- and lifespan in flies.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Hinterding, Helena Maria hinthe@gmail.com UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-706134
Date:	December 2022
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Außeruniversitäre Forschungseinrichtungen > MPI for Biology of Ageing
Subjects:	Life sciences
Uncontrolled Keywords:	Keywords Language ageing English genetics English functional characterisation English
Date of oral exam:	3 March 2023
Referee:	Name Academic Title Partridge, Linda Prof. Dr. Nürnberg, Peter Prof. Dr. Deelen, Joris Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/70613