Plasma membrane permeabilization following cell death: many ways to dye!

Effects of inorganic phosphate on stem cells isolated from human exfoliated deciduous teeth

Calcium phosphate-based materials (CaP) are introduced as potential dental pulp capping materials for deciduous teeth. The present study investigated the influence of inorganic phosphate (Pi) on regulating stem cells isolated from human exfoliated deciduous teeth (SHED). SHEDs were treated with Pi. Cell cycle progression and apoptosis were examined using flow cytometry analysis. Osteo/odontogenic and adipogenic differentiation were analyzed using alizarin red S and oil red O staining, respectively. The mRNA expression profile was investigated using a high-throughput RNA sequencing technique. Pi increased the late apoptotic cell population while cell cycle progression was not altered. Pi upregulated osteo/odontoblastic gene expression and enhanced calcium deposition. Pi-induced mineralization was reversed by pretreatment of cells with Foscarnet, or p38 inhibitor. Pi treatment inhibited adipogenic differentiation as determined by decreased PPARγ expression and reduced intracellular lipid accumulation. Bioinformatic analysis of gene expression profiles demonstrated several involved pathways, including PI3K/AKT, MAPK, EGFR, and VEGF signaling. In conclusion, Pi enhanced osteo/odontogenic but inhibited adipogenic differentiation in SHED.

New substituted benzoxazine derivatives as potent inducers of membrane permeability and cell death

The search for new agents targeting different forms of cell death is an important research focus for developing new and potent antitumor therapies. As a contribution to this endeavor, we have designed and synthesized a series of new substituted 3,4-dihydro-2H-1,4-benzoxazine derivatives. These compounds have been evaluated for their efficacy against MCF-7 breast cancer and HCT-116 colon cancer cell lines. Overall, substituting this heterocycle led to improved antiproliferative activity compared to the unsubstituted derivative 1. The most active compounds, 2b and 4b, showed IC50 values of 2.27 and 3.26 μM against MCF-7 cells and 4.44 and 7.63 μM against HCT-116 cells, respectively. To investigate the mechanism of action of the target compounds, the inhibition profile of 8 kinases involved in cell signaling was studied highlighting residual activity on HER2 and JNK1 kinases. 2b and 4b showed a consistent binding mode to both receptor kinases, establishing significant interactions with known and catalytically important domains and residues. Compounds 2b and 4b exhibit potent cytotoxic activity by disrupting cell membrane permeability, likely triggering both inflammatory and non-inflammatory cell death mechanisms. This dual capability increases their versatility in the treatment of different stages or types of tumors, providing greater flexibility in clinical applications.

Synthetic protein circuits for programmable control of mammalian cell death

Natural cell death pathways such as apoptosis and pyroptosis play dual roles: they eliminate harmful cells and modulate the immune system by dampening or stimulating inflammation. Synthetic protein circuits capable of triggering specific death programs in target cells could similarly remove harmful cells while appropriately modulating immune responses. However, cells actively influence their death modes in response to natural signals, making it challenging to control death modes. Here, we introduce naturally inspired "synpoptosis" circuits that proteolytically regulate engineered executioner proteins and mammalian cell death. These circuits direct cell death modes, respond to combinations of protease inputs, and selectively eliminate target cells. Furthermore, synpoptosis circuits can be transmitted intercellularly, offering a foundation for engineering synthetic killer cells that induce desired death programs in target cells without self-destruction. Together, these results lay the groundwork for programmable control of mammalian cell death.

Human tissue-resident peritoneal macrophages reveal resistance towards oxidative cell stress induced by non-invasive physical plasma

In the context of multimodal treatments for abdominal cancer, including procedures such as cytoreductive surgery and intraperitoneal chemotherapy, recurrence rates remain high, and long-term survival benefits are uncertain due to post-operative complications. Notably, treatment-limiting side effects often arise from an uncontrolled activation of the immune system, particularly peritoneally localized macrophages, leading to massive cytokine secretion and phenotype changes. Exploring alternatives, an increasing number of studies investigated the potential of plasma-activated liquids (PAL) for adjuvant peritoneal cancer treatment, aiming to mitigate side effects, preserve healthy tissue, and reduce cytotoxicity towards non-cancer cells. To assess the non-toxicity of PAL, we isolated primary human macrophages from the peritoneum and subjected them to PAL exposure. Employing an extensive methodological spectrum, including flow cytometry, Raman microspectroscopy, and DigiWest protein analysis, we observed a pronounced resistance of macrophages towards PAL. This resistance was characterized by an upregulation of proliferation and anti-oxidative pathways, countering PAL-derived oxidative stress-induced cell death. The observed cellular effects of PAL treatment on human tissue-resident peritoneal macrophages unveil a potential avenue for PAL-derived immunomodulatory effects within the human peritoneal cavity. Our findings contribute to understanding the intricate interplay between PAL and macrophages, shedding light on the promising prospects for PAL in the adjuvant treatment of peritoneal cancer.

Paradoxical roles for programmed cell death signaling during viral infection of the central nervous system

Programmed cell death (PCD) is an essential mechanism of antimicrobial defense. Recent work has revealed an unexpected diversity in the types of PCD elicited during infection, as well as defined unique roles for different PCD modalities in shaping the immune response. Here, we review recent work describing unique ways in which PCD signaling operates within the infected central nervous system (CNS). These studies reveal striking complexity in the regulation of PCD signaling by CNS cells, including both protective and pathological outcomes in the control of infection. Studies defining the specialized molecular mechanisms shaping PCD responses in the CNS promise to yield much needed new insights into the pathogenesis of neuroinvasive viral infection, informing future therapeutic development.

Plasma membrane perforation by GSDME during apoptosis-driven secondary necrosis

Secondary necrosis has long been perceived as an uncontrolled process resulting in total lysis of the apoptotic cell. Recently, it was shown that progression of apoptosis to secondary necrosis is regulated by Gasdermin E (GSDME), which requires activation by caspase-3. Although the contribution of GSDME in this context has been attributed to its pore-forming capacity, little is known about the kinetics and size characteristics of this. Here we report on the membrane permeabilizing features of GSDME by monitoring the influx and efflux of dextrans of different sizes into/from anti-Fas-treated L929sAhFas cells undergoing apoptosis-driven secondary necrosis. We found that GSDME accelerates cell lysis measured by SYTOX Blue staining but does not affect the exposure of phosphatidylserine on the plasma membrane. Furthermore, loss of GSDME expression clearly hampered the influx of fluorescently labeled dextrans while the efflux happened independently of the presence or absence of GSDME expression. Importantly, both in- and efflux of dextrans were dependent on their molecular weight. Altogether, our results demonstrate that GSDME regulates the passage of compounds together with other plasma membrane destabilizing subroutines.