Our project uncovered new insights into the mechanism and regulation of gasdermin activation, the control and execution of pyroptotic cell death and the role of gasdermins in vivo.
1) Gasdermin pore formation is regulated even after gasdermin cleavage and pore formation, on the level of membrane repair. Specifically, we found that GSDMD pore formation induced Calcium influx into the cell, which resulted in a recruitment of ESCRT-III complex components towards the membrane region containing gasdermin pores that drive the formation vesicles containing GSDMD pores that were shed from cells. Finally, we found that inactivation of ESCRT-III reduced survival of inflammasome-activated cells.
Ref: Rühl et al. Science 2018
2) We showed that apoptotic caspases-8 cleaves and activates gasdermin-D, thereby switching apoptosis to pyroptosis, and that this plays an important physiological role in in vivo model of TNF-driven cytokine storm and host defense against infection with Yersinia bacteria. Interestingly, we also found that GSDMD and GSDME play cell-type-specific roles in host defense against Yersinia infections.
Ref: Chen et al. EMBO J 2019, Dimarco et al. Sci Adv 2020, Chen et al. PNAS 2021
3) We also explored the effects of GSDMD deficiency in inflammasome-activated cells, and found that GSDMD-deficiency did not completely abrogate cell death. We found that in absence of GSDMD, caspase-1 cleaved BID to induce extrinsic apoptosis and rapid necrotic death. This finding revealed an unexpected redundancy in cellular cell death pathways, and new connections between inflammatory caspases and induction of apoptosis.
Ref: Heilig et al. LSA 2021
4) Using super-resolution microscopy and Cryo-EM microscopy we determined the atomic structure of NINJ1 filaments that form downstream of GSDMD activation and permeabilize the plasma membrane.
Ref: Degen et al. Nature 2023
5) To extend our findings from pyroptosis to other forms of cell death, we investigated plasma membrane rupture during ferroptosis, a novel form of death dependent on iron-mediated ROS production and subsequent lipid peroxidation, and showed that NINJ1 acts as a driver of membrane rupture in ferroptotic cells.
Ref: Ramos et al. EMBO J 2024
Exploitation and dissemination:
The results from this project were published in high impact journals and presented at over 20+ conferences.
Furthermore, we promoted their disseminations through press releases and on twitter.
Articles for the lay audience were also published in EU research in Spring 2020, and on the CORDIS website (upcoming).
The project also contributed to technical advances in the field of cell death: As part of the project we developed a novel toolset for the optogenetic induction of different forms of cell death, among them pyroptosis, apoptosis and necroptosis. Optogenetics allows the manipulation of proteins using blue light illumination and our toolset can be used to kill individual cells in a multicellular tissue to subsequently analyze the response of neighboring cells, or precise timing of cell death induction. The toolset was published and made available to other researchers via Addgene.org.
Ref: Shkarina et al. JBC 2022.
