Project description:Lipoic acid is an essential enzyme cofactor in central metabolic pathways. Due to its claimed antioxidant properties, racemic (R/S)-lipoic acid is used as a food supplement but is also investigated as a pharmaceutical in over 180 clinical trials covering a broad range of diseases. Moreover, (R/S)-lipoic acid is an approved drug for the treatment of diabetic neuropathy. However, its mechanism of action remains elusive. Here, we performed chemoproteomics-aided target deconvolution of lipoic acid and its active close analog lipoamide. We find that histone deacetylases HDAC1, HDAC2, HDAC3, HDAC6, HDAC8, and HDAC10 are molecular targets of the reduced form of lipoic acid and lipoamide. Importantly, only the naturally occurring (R)-enantiomer inhibits HDACs at physiologically relevant concentrations and leads to hyperacetylation of HDAC substrates. The inhibition of HDACs by (R)-lipoic acid and lipoamide explain why both compounds prevent stress granule formation in cells and may also provide a molecular rationale for many other phenotypic effects elicited by lipoic acid.
Project description:Here we report an unexpected chemistry through which ITC-protein adduct forms a stable N-terminal dihydrothiazole peptide adduct during proteolysis. This proteolysis-assisted cyclization (PAC) reaction can be harnessed for developing affinity-based and activity-based chemoproteomic methods to site-specifically profile targets of ITCs.
Project description:Here we show that biotin-labelled miR-34a can be loaded to AGO2, and AGO2 immunoprecipitation can pulldown biotinylated miR-34a (Bio-miR pulldown). RNA-sequencing (RNA-seq) of the Bio-miR pulldown RNAs efficiently identified miR-34a mRNA targets, which could be verified with luciferase assays. In contrast to the approach of Bio-miR pulldown, RNA-seq of miR-34a overexpression samples had limited value in identifying direct targets of miR-34a. It seems that pulldown of 30 -Biotin-tagged miRNA can identify bona fide microRNA targets at least for miR34a.
Project description:CD34 positive hematopoietic stem cells were differentiated into erythroid lineage. Next generation sequencing (NGS) of 5hmC affinity pulldown and RNAseq were performed in four time point of different stages of erythroid differentiation. 4 RNA-Seq Samples (d0, d3, d7 and d10); 4 affinity-pulldown (d0, d3, d7 and d10), and 4 input samples (d0, d3, d7 and d10).
Project description:Parasite lysates were centrifuged (20,000 g, 4°C, 15 min). Beads (blank and with linker attached) were washed 3× with water then twice with lysis buffer. The lysate (~2 mg total protein) was first incubated with 2 mg blank beads for 30 min at 4°C with rotating agitation. The lysate was divided into two then incubated with either 1% DMSO or 100 µM DDD01510706 (competitor) for 30 min at 4°C with agitation. Finally, lysates were incubated with 2 mg of compound-bound beads for 1 h at 4°C with agitation. The beads were then washed 3× with wash buffer (0.8% (w/v) octyl β-D-glucopyranoside, 50 mM Tris pH 8.0, 5 mM EDTA, 1 mg/mL BSA) and 2× Tris-buffered saline (TBS; 50 mM Tris-Cl pH 7.5, 150 mM NaCl). Samples were run 1.5 cm into a Bis-Tris 10% (w/v) acrylamide gel and stained with Coomassie quick reagent for 30 min. The entire gel bands were removed and subjected to in-gel reduction with 10 mM dithiothreitol, alkylation with 50 mM iodoacetamide and digestion with 12.5 μg/mL trypsin (Pierce) for >16 h at 37°C. Recovered tryptic peptides were then vacuum dried prior to analysis
Project description:We proceeded to competitive chemoproteomic profiling with conidiogenone C probe in LPS-stimulated RAW264.7 cell lysates. The lysis was then reacted with azide-biotin, and after enrichment and digestion, the peptides were labeled as “light, “medium” or “heavy” by dimethyl labeling. The labeled proteins were identified and quantified by LC-MS/MS analysis.
Project description:We performed pulldown assays followed by mass-spectrometry analysis using biotin-tagged 13-cis retinoic acid to identify its binding targets in HeLa cells