Project description:Eukaryotic translation initiation factor 4E (eIF4E)–binding protein 1 (4E-BP1) inhibits cap-dependent translation in eukaryotes by competing with eIF4G for an interaction with eIF4E. Phos-phorylation at Ser-83 of 4E-BP1 occurs during mitosis through the activity of cyclin-dependent kinase 1 (CDK1)/cyclin B rather than through canonical mTOR kinase activity. Here, we investi-gated the interaction of eIF4E with 4E-BP1 or eIF4G during interphase and mitosis. We observed that 4E-BP1 and eIF4G bind eIF4E at similar levels during interphase and mitosis. The most highly phosphorylated mitotic 4E-BP1 isoform (δ) did not interact with eIF4E, whereas a distinct 4E-BP1 phospho-isoform, EB-γ—phosphorylated at Thr-70, Ser-83, and Ser-101—bound to eIF4E during mitosis. Two-dimensional gel electropho-retic analysis corroborated the identity of the phosphorylation marks on the eIF4E-bound 4E-BP1 isoforms and uncovered a population of phosphorylated 4E-BP1 molecules lacking Thr-37/Thr-46–priming phosphorylation. Moreover, proximity ligation assays for phospho–4E-BP1 and eIF4E revealed different in situ interactions during interphase and mitosis. The eIF4E:eIF4G interaction was not inhibited, but rather increased in mitotic cells, consistent with active translation initiation during mitosis. Phospho-defective substitution of 4E-BP1 at Ser-83 did not change global translation or individual mRNA translation profiles as measured by single-cell nascent protein synthesis and eIF4G RNA-immunoprecipitation sequencing. Mitotic 5’-terminal oligopyrimidine RNA translation was active and, unlike interphase translation, resistant to mTOR inhibition. Our findings reveal the phosphorylation profiles of 4E-BP1 isoforms and their interactions with eIF4E throughout the cell cycle and indicate that 4E-BP1 does not specifically inhibit translation initiation during mitosis.
Project description:D-galactose orally intake ameliorate DNCB-induced atopic dermatitis by modulating microbiota composition and quorum sensing. The increased abundance of bacteroidetes and decreased abundance of firmicutes was confirmed. By D-galactose treatment, Bacteroides population was increased and prevotella, ruminococcus was decreased which is related to atopic dermatitis.
Project description:The time-resolved impact of monensin on the active rumen microbiome in a rumen-simulating technique (Rusitec) was studied with metaproteomic and metabolomic approaches. Upon monensin treatment, decreased catabolism linked to fiber degradation was observed by the reduced abundance of proteins assigned to fibrolytic bacteria and glycoside hydrolases, sugar transporters and carbohydrate metabolism. Reduced amounts of ammonium as well as branched-chain fatty acids pointed towards a decreased proteolytic activity. The family Prevotellaceae exhibited increased resilience in the presence of monensin, with a switch of metabolism from acetate to succinate production. Prevotella species harbor a membrane bound electron transfer complex, which drives the reduction of fumarate to succinate, the substrate for propionate production in the rumen habitat. Besides the increased succinate production, a concomitant depletion of methane concentration was observed upon monensin exposure. Our study demonstrates that Prevotella sp. shifts its metabolism successfully in response to monensin exposure and Prevotellaceae represents the key bacterial family stabilizing the rumen microbiota during exposure to monensin.