Biology subjects

Kwiatkowska, K.

Publications and source records attributed to Kwiatkowska, K..

3 recordsLinked to original sources

bioRxiv2023

Flotillins affect LPS-induced TLR4 signaling by modulating the trafficking and abundance of CD14

Lipopolysaccharide induces a strong pro-inflammatory reaction of macrophages upon activation of Toll-like 4 receptor (TLR4) with the assistance of CD14 protein. Considering a key role of plasma membrane rafts in CD14 and TLR4 activity and the significant impact exerted on that activity by endocytosis and intracellular trafficking of the both LPS acceptors, it seemed likely that the pro-inflammatory reaction could be modulated by flotillins. Flotillin-1 and -2 are scaffolding proteins associated with plasma membrane rafts and also with endo-membranes, affecting both the plasma membrane dynamics and intracellular protein trafficking. To verify the above hypothesis, a set of shRNA was used to down-regulate flotillin-2 in Raw264 cells, which were found to also become deficient in flotillin-1. The flotillin deficiency inhibited strongly the TRIF-dependent endosomal signaling of LPS-activated TLR4, and to a lower extent also the MyD88-dependent one, without affecting the cellular level of TLR4. In contrast, the depletion of flotillins down-regulated the CD14 mRNA level and the total cellular content of CD14 protein, and decreased the amount of CD14 on the cell surface. The constitutive CD14 endocytosis remained unchanged but CD14 recycling was enhanced via EEA1-positive early endosomes and golgin-97-positive trans-Golgi network, likely to compensate for the depletion of the cell-surface CD14. Notably, a paucity of surface CD14 in resting cells can inhibit TLR4 signaling after the stimulation of cells with LPS. In conclusion, we have shown here that flotillins modulate the pro-inflammatory response of macrophages to LPS by affecting the abundance of CD14.

immunology↗

bioRxiv2023

DGKepsilon is S-palmitoylated at the cysteine located at the cytoplasmic end of its N-terminal transmembrane fragment

Diacylglycerol kinase-{varepsilon} (DGK{varepsilon}) catalyzes phosphorylation of diacylglycerol to phosphatidic acid with a unique specificity toward 1-stearoyl-2-arachidonoyl-sn-glycerol which is a backbone of phosphatidylinositol (PI). Owing to this specificity, DGK{varepsilon} is involved in the PI cycle maintaining the cellular level of phosphorylated PI derivatives of signaling activity, and was also found crucial for lipid metabolism. DGK{varepsilon} dysfunction is linked with the development of atypical hemolytic uremic syndrome and possibly other human diseases. Despite the DGK{varepsilon} significance, data on its regulation by co/posttranslational modifications are scarce. Here we report that DGK{varepsilon} is S-palmitoylated at Cys38/40 (mouse/human DGK{varepsilon}) located in the cytoplasmic end of its N-terminal putative transmembrane fragment. The S-palmitoylation of DGK{varepsilon} was revealed by metabolic labeling of cells with a palmitic acid analogue followed by click chemistry, and with acyl-biotin and acyl-PEG exchange assays. The S-acyltransferases zDHHC7 and zDHHC17, and the zDHHC6/16 tandem were found to catalyze DGK{varepsilon} S-palmitoylation which also increased the DGK{varepsilon} abundance. Mouse DGK{varepsilon}-Myc ectopically expressed in HEK293 cells localized to the endoplasmic reticulum where zDHHC6/16 reside and in small amounts also to the Golgi apparatus where zDHHC7 and zDHHC17 are present. The Cys38Ala substitution upregulated while hyperpalmitoylation of wild type DGK{varepsilon} reduced the kinase activity, indicating an inhibitory effect of the Cys38 S-palmitoylation. Additionally, the substitution of neighboring Pro31 with Ala also diminished the activity of DGK{varepsilon}. Taken together, our data indicate that S-palmitoylation can fine-tune DGK{varepsilon} activity in distinct cellular compartments, possibly by affecting the distance between the kinase and its substrate in a membrane.

cell biology↗

bioRxiv2021

Faces of men with high serum testosterone are less attractive for women during the fertility phase of the menstrual cycle

The attractiveness of the human face plays an essential role in mating as it may signal the genetic suitability of a mate. The controversial ovulatory shift hypothesis postulates that women in the fertile phase of the menstrual cycle would prefer faces of masculine men with high testosterone that signals good genes, whereas in the non-fertile phase they prefer traits signaling the willingness to provide parental care. To examine relationships between mens testosterone and womens preferences for mens faces on day 13 of the menstrual cycle, 19 young women rated the attractiveness of images of the natural faces of 77 young men. Using advanced Bayesian multilevel modeling we showed that the attractiveness of mens faces is significantly lower in men with a high concentration of serum total testosterone, even taking into account the concentration of serum estrogen in the raters. The average mens face composited from images of 39 faces rated above pool median attractiveness rate, was slightly narrower than the average face composited from 38 less attractive faces. Our results challenge the ovulatory shift hypothesis as faces of males with high circulating testosterone were rated as less attractive than faces of males with lower testosterone by women on the fertile phase of the cycle.

evolutionary biology↗