Lipidomic processes in homeostatic and LPS-modified cell renewal cycle. Role of phosphatidylinositol 3-kinase pathway in biomembrane synthesis and restitution of apical epithelial membrane.

BACKGROUND Nuclear transcriptome initiates specific proteome that facilitates metabolic events culminating in restitution of cell components and reproduction of the discrete cellular function, but the magnitude of various genes induction and following proteomic, lipidomic, and glycomic processes provide distinctness to the final product and its function. In homeostasis, the challenged cell responds to stimuli in defined and predictable mode but in the disease such as ulcerative erosions the ablation of cell survival signals and cell apoptosis is enhanced. Therefore, to uncover the discreteness and dissimilarity of the pathological processes induced by elicobacter pylori (H. pylori) lipopolysaccharide (LPS), not only measurement of the genomic events is crucial, but a complete cycle of events reproducing the cell specific proteins, lipids, and cell-specific environment created in situ require thorough investigation. METHODS An impact of H. pylori LPS-induced processes on posttranslational lipidomic activity in endoplasmic reticulum (ER), Golgi and apical membrane was evaluated in the in vitro paradigm assembled with components of the rat gastric mucosal epithelial cells. RESULTS In ER, the signals commanding synthesis of biomembrane in the presence of control, the LPS-derived or LPS-admixed cytosol was identical. The assembled vesicles contained the same amount of apoprotein and had the same lipid composition. Their biomembrane contained the same amount of sphingolipids in form of ceramide, which is determining factor of the ER-transport vesicle completion. The transport of apoprotein in ER vesicles to Golgi was also not changed. In Golgi, LPS-derived cytosol affected two distinct and concurrent with assembly of Golgi transport vesicles processes. The LPS-derived cytosol affected formation of Golgi transport vesicles destined to apical membrane and the incorporation (fusion) of Golgi vesicles with apical epithelial membrane. The LPS-derived cytosol decreased the production of Golgi vesicles by 15% and their fusion with the apical epithelial membrane by 83%. In contrast with wortmannin, the LPS-derived cytosol had no impact on Golgi transport vesicles association with the epithelial membrane. CONCLUSIONS We concluded that LPS interferes with MAPK-dependent activation of cytosolic PLA(2) since MAPKs immunoprecipitate added to the LPS-cytosol restored activation of cytosolic PLA(2)-specific fusion of the Golgi transport vesicles with apical mucosal cell membrane. On the other hand, wortmannin that inhibited the association of Golgi transport vesicles with apical membrane, interferes with cytosolic activity that controls association of PI3K-containing Golgi vesicles with the apical membrane. Together, our studies present evidence that allow to conclude that LPS affects MAPK-specific phosphorylation and PLA(2)-assisted membranes' fusion, whereas wortmannin affects association of PI3K- and PI3P-containing Golgi-derived transport vesicles with the membrane. In the final outcome, both actions result in a diminished or inhibited restitution of apical membrane.