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Abstract Sphaeropsidins are iso-pimarane diterpenes produced by phytopathogenic fungi that display promising anticancer activities. Sphaeropsidin A, in particular, has been shown to counteract regulatory volume increase, a process used by cancer cells to avoid apoptosis. This study reports the hemi-synthesis of new lipophilic derivatives obtained by modifications of the C15,C16-alkene moiety. Several of these compounds triggered severe ER swelling associated with strong proteasomal inhibition and consequently cell death, a feature that was not observed with respect to mode of action of the natural product. Significantly, an analysis from the National Cancer Institute sixty cell line testing did not reveal any correlations between the most potent derivative and any other compound in the database, except at high concentrations (LC50). This study led to the discovery of a new set of sphaeropsidin derivatives that may be exploited as potential anti-cancer agents, notably due to their maintained activity towards multidrug resistant models.

Abstract Shiga toxin-producing Escherichia coli (STEC) are major foodborne pathogens that cause human diseases ranging from diarrhea to life-threatening complications including hemolytic–uremic syndrome. Virulence of STEC strains and their ability to cause severe diseases are associated with the activity of prophage-encoded Shiga toxins (Stxs). The first objective of this work was to isolate and characterize the Stx2d phage from STEC O80:H2 and to study the transfer of this phage in non-STEC strains. The second objective was to assess the survival of Galleria mellonella larvae inoculated with these transduced strains. Firstly, one bacteriophage isolated from a STEC O80:H2 strain was used to infect six non-STEC strains, resulting in the conversion of three strains. Then, stability assays were performed, showing that this phage was stable in the new STEC strains after three successive subculturing steps, as confirmed by a combination of short and long read genome sequencing approaches. This phage, vB_EcoS_ULI-O80_Stx2d, is resistant to moderate temperature and pH. It belongs to a currently unclassified genus and family within the Caudoviricetes class, shares 98% identity with Stx2_112808 phage and encodes several proteins involved in the lysogenic cycle. The yecE gene was identified at the insertion site. Finally, G. mellonella experiments showed that the transduced strains caused significantly higher mortality rates than the corresponding non-STEC strains. In conclusion, this study showed that stx2d gene from O80:H2 E. coli can be transferred to non-STEC strains and contributes to their virulence.

Abstract The AMP-activated kinase (AMPK) is a major energy sensor metabolic enzyme that is activated early during T cell immune responses but its role in the generation of effector T cells is still controversial. Using both in vitro and in vivo models of T cell proliferation, we show herein that AMPK is dispensable for early TCR signaling and short-term proliferation but required for sustained long-term T cell proliferation and effector/memory T cell survival. In particular, AMPK promoted accumulation of effector/memory T cells in competitive homeostatic proliferation settings. Transplantation of AMPK-deficient hematopoïetic cells into allogeneic host recipients led to a reduced graft-versus-host disease, further bolstering a role for AMPK in the expansion and pathogenicity of effector T cells. Mechanistically, AMPK expression enhances the mitochondrial membrane potential of T cells, limits reactive oxygen species (ROS) production, and resolves ROS-mediated toxicity. Moreover, dampening ROS production alleviates the proliferative defect of AMPK-deficient T cells, therefore indicating a role for an AMPK-mediated ROS control of T cell fitness.