Signaling pathways involved in adaptive responses to cell membrane disruption

Inflicting, Monitoring, Visualizing, and Quantitating Various Sterile Membrane Damages and the Repair Response in Dictyostelium discoideum

Eukaryotic cells have been constantly challenged throughout their evolution by pathogens, mechanical stresses, or toxic compounds that induce plasma membrane (PM) or endolysosomal membrane damage. The survival of the wounded cells depends on damage detection and repair machineries that are evolutionary conserved between protozoan, plants, and animals. We use the social amoeba Dictyostelium discoideum as a model system to study bacteria, mechanical or sterile membrane damage that allows us to identify and monitor factors involved in PM, endolysosomal damage response (ELDR), and endolysosomal homeostasis. Importantly, the sterile damage techniques presented here homogenously affect cell populations, which allows to phenotype mutant strains and quantify various aspects of cell fitness using live cell microscopy. This is instrumental to functionally assess genes involved in the repair of damaged plasma membrane or intracellular compartments and the degradation of extensively damaged compartments. Here, we describe how to inflict sterile PM or endolysosomal membrane damage, how to monitor the cell-intrinsic response to damage, and how to proxy proton leakage from damaged acidic compartments and quantify cell viability.

Change in membrane fluidity induced by polyphenols is highly dependent on the position and number of galloyl groups

The cell membrane fluidity was very important in adipogenesis and galloyl groups on polyphenolic structures could enhance their antiadipogenic activity. However, the effect of polyphenols on membrane fluidity and the role of galloyl groups in fluidity changes remain unclear. Therefore, the present study chose structurally different polyphenols to compare their effects on the membrane morphology and fluidity of 3T3-L1 preadipocytes, and then the reasons behind the changes of membrane fluidity induced by galloylated polyphenols were explored from structural and molecular insights using liposome model and molecular dynamic simulation technology. Our results indicated that galloylated polyphenols could significantly change 3T3-L1 cell membrane morphology and decrease membrane fluidity, while non-galloylated ones could not. The membrane interference effect of polyphenols was enhanced as the number of galloyl groups increased. Morever, the decrease in membrane fluidity induced by galloylated polyphenols was due to the disturbance of polyphenols on lipid alkyl chains in the cell membrane. Galloylated polyphenols could not only locate in the polar head, but also insert into hydrophobic center of lipid bilayer to interfere with the lipid alkyl chains arrangement, thus decreasing the membrane fluidity and showing strong affinity for the membrane. In addition, differences in position of galloyl groups in polyphenols induced distinct effect on cell membranes interactions, thus affecting the binding manner and bioactivity. The results expanded the understanding on the strong antiadipogenic activity of galloylated polyphenols through the aspect of their effects on cell membrane by both experimental and theoretically simulated ways.

Plasma membrane integrity: implications for health and disease

Plasma membrane integrity is essential for cellular homeostasis. In vivo, cells experience plasma membrane damage from a multitude of stressors in the extra- and intra-cellular environment. To avoid lethal consequences, cells are equipped with repair pathways to restore membrane integrity. Here, we assess plasma membrane damage and repair from a whole-body perspective. We highlight the role of tissue-specific stressors in health and disease and examine membrane repair pathways across diverse cell types. Furthermore, we outline the impact of genetic and environmental factors on plasma membrane integrity and how these contribute to disease pathogenesis in different tissues.