Dissertation - Simon Prokisch-Chalas
On Friday, 2026-03-13 at 13:00, the public is invited to attend the PhD thesis defense of Simon Prokisch-Chalas in Vivi Täckholmssalen, Svante Arrhenius väg 20. The thesis is entitled “Intracellular connectivity during stress and aging.”
By:
Simon Prokisch-Chalas, Department of Molecular Biosciences, Stockholm University
Supervisor:
Professor Sabrina Büttner, Department of Molecular Biosciences, Stockholm University
Chair:
Professor Per Ljungdahl, Department of Molecular Biosciences, Stockholm University
Opponent:
Victoria Menendez-Benito; Karolinska Institute; Department of Laboratory Medicine
Commitee:
Marija Cvijovic, Department of Mathematical Sciences, University of Gothenburg, Chalmers
Mikael Molin, Department of Biology and Biological Engineering, Chalmers
Kristina Jonas, Department of Molecular Biosciences, Stockholm University
Abstract:
Aging is a natural, irreversible process characterized by a gradual decline in physiological functions and an increased susceptibility to diseases due to the accumulation of molecular and cellular damage over time. It is a complex, multi-factorial process involving a wide range of biological changes, such as genomic instability, epigenetic alterations, and a decay in proteostasis. Understanding cellular changes caused by aging is essential for improving human health and quality of life in old age and preventing age-related diseases. To study aging processes and their effects on cellular structures and general fitness the eukaryote budding yeast (Saccharomyces cerevisiae) was used in this study. Despite its simplicity, yeast is an optimal model organism for aging research as many cellular processes are conserved in more complex eukaryotes, including humans.
In Paper I, the ability of chronologically aged cells to re-enter the cell cycle was analyzed. Depending on whether glucose or phosphate was the limiting nutrient driving entry into stationary phase, the lipid profile of aged cells differed drastically. The alteration in lipid composition contributed to maintenance and exit of quiescent cells differentially.
In Paper II, the effects of aging on the organization of the endoplasmic reticulum (ER) and its microdomains were studied. Here, we showed that partitioning into ER microdomains impacts autophagic protein turnover during cellular aging and that cellular aging causes a gradual increase of ER microdomains, in particular in the cortical ER. We also established that the transmembrane length of ER membrane proteins determines their final localization as well as their stability.
Finally, in Paper III, we established a direct link between the proteolytic capacity of the vacuole and mitochondrial function. Whereas increasing this capacity was beneficial for mitochondrial functionality and abundance as well as cellular survival, decreasing it led to opposite effects. The beneficial effects were dependent on the augmented formation of membrane contact sites between the vacuole and mitochondria.
Last updated: 2026-02-20
Source: MBW