PSL Chemical Biology Symposia: Recent Progress in Ferroptosis.

This symposium is the 5th PSL (Paris Sciences & Lettres) Chemical Biology meeting (2015, 2016, 2019, 2023, 2024) held at Institut Curie. This initiative originally started at Institut de Chimie des Substances Naturelles (ICSN) in Gif-sur-Yvette, with a strong focus on chemistry. It was then continued at the Institut Curie (2015) covering a larger scope, before becoming the official PSL Chemical Biology meeting. This latest edition hosted around 150 participants and was focused on the burgeoning field of ferroptosis, its mechanism and implications in health and disease. While not initially planned, it was felt that the next large Ferroptosis venue (CSHA, China) would not happen before late 2024. A discussion involving Conrad, Birsoy, Ubellacker, Brabletz and Rodriguez next to lake Como in Italy sponsored by the DKFZ, prompted us to fill in this gap and to organize a Ferroptosis meeting in Paris beforehand.

PSL Chemical Biology Symposia Third Edition: A Branch of Science in its Explosive Phase.

This symposium is the third PSL (Paris Sciences & Lettres) Chemical Biology meeting (2016, 2019, 2023) held at Institut Curie. This initiative originally started at Institut de Chimie des Substances Naturelles (ICSN) in Gif-sur-Yvette (2013, 2014), under the directorship of Professor Max Malacria, with a strong focus on chemistry. It was then continued at the Institut Curie (2015) covering a larger scope, before becoming the official PSL Chemical Biology meeting. This latest edition was postponed twice for the reasons that we know. This has given us the opportunity to invite additional speakers of great standing. This year, Institut Curie hosted around 300 participants, including 220 on site and over 80 online. The pandemic has had, at least, the virtue of promoting online meetings, which we came to realize is not perfect but has its own merits. In particular, it enables those with restricted time and resources to take part in events and meetings, which can now accommodate unlimited participants. We apologize to all those who could not attend in person this time due to space limitation at Institut Curie.

The fine-tuning of endoplasmic reticulum stress response and autophagy activation during trophoblast syncytialization.

The syncytiotrophoblast (STB) is a multinuclear layer forming the outer surface of the fetal part of the placenta deriving from villous cytotrophoblastic cell (vCTB) fusion and differentiation. This syncytialization process is characterized by morphological and biochemical alterations of the trophoblast, which probably require removal of pre-existing structures and proteins to maintain cell homeostasis and survival. Interestingly, autophagy, which allows degradation and recycling of cellular components, was shown to be activated in syncytiotrophoblast. Here we examined the involvement of endoplasmic reticulum stress (ERS) response in autophagy activation during vCTB syncytialization. We first demonstrated the activation of ERS response and autophagy during the time course of trophoblastic cell fusion and differentiation. Alteration of autophagy activation in vCTB by chemical treatments or Beclin-1 expression modulation leads to a decrease in trophoblastic syncytialization. Furthermore, ERS response inhibition by chemical treatment or siRNA strategy leads to a default in syncytialization, associated with alteration of autophagy markers and cell survival. From these data, we suggest that ERS response, by fine regulation of autophagy activation, may serve as an adaptive mechanism to promote cell survival during trophoblastic syncytialization.