PhD Scientific Days 2023

Budapest, 22-23 June 2023

Molecular Sciences III.

The study of autophagy-dependent survival in endoplasmic reticulum stress

Marianna Holczer, Annamária Lehel, Boglárka Besze, Orsolya Kapuy

Semmelweis University, Department of Molecular Biology, Budapest, Hungary

Text of the abstract

The endoplasmic reticulum (ER) plays a crucial role in cellular homeostasis by integrating many signaling processes. When the internal homeostasis of the ER is disrupted, ER stress is generated in the cell. In response to ER stress, first, the autophagic self-digestive process is activated to promote cell survival. However, cell death is induced in case of excessive level of ER stress. We have recently proposed a regulatory network, where the life-and-death decision of the ER stress response mechanism is determined by positive and negative feedback loops of autophagy and cell death controllers and mTORC1-AMPK pathways. We have previously shown that the decision between life and death can be influenced by disrupting the balance between mTORC1 and AMPK using natural compounds (e.g. EGCG).
The aim of the present study was to investigate the role of sulforaphane (SFN) in promoting autophagy-dependent survival. Therefore, we implemented SFN pre-treatment and co-treatment combined with ER stress to investigate how the activation of autophagy at different times point may affect in different stages of ER stress-related diseases.
We approached our scientific analysis from a systems biological perspective by using both theoretical and molecular biological techniques. For molecular biological experiments, HEK293T cell line was used, meanwhile the dynamical characteristic of the regulatory network was described by mathematical modeling.
We found that SFN induced autophagy or cell death in a concentration- and time-dependent manner. The short treatment (2 h) at low concentrations promoted autophagy, whereas the longer treatment (4 h, 24 h) at higher concentrations activated cell death. We saw that SFN activated autophagy in a mTORC1-dependent manner and that the presence of ULK1 was required for its function. Based on these results, we selected a low concentration of SFN where autophagy was activated and combined this with short and long ER stress (thapsigargin treatment). The SFN was able to promote cell survival via autophagy induction in each treatment. Based on these results, our mathematical model can simulate the effects of the treatments correctly.
Supported by the ÚNKP-22-4-II-SE-21 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund.