Project description:This is supplemental raw data for Abe et al., 2022. Proteome analysis and phospho-proteome analysis using mouse liver prepared at 6 circadian time points (CT2, 6, 10, 14, 18, 22). In the delta-RRE mutant, two RRE sequences are removed from 5'UTR of mouse Bmal1 gene.
Project description:RNF213 is novel transthiolating E3 ligase that is activated by ATP. To determine whether cellular RNF213 is activated by elevated ATP levels, we electroplated an E3 activity-based probe into HEK293 cells stably expressing RNF213 in a knockout background. DIA analysis was performed in cells that were coelectroporated with the poorly hydrolysable ATP analog, ATPgS, or buffer control.
Project description:Homeostatic control of intracellular ionic strength is essential for protein, organelle and genome function, yet mechanisms that sense and enable adaptation to ionic stress remain poorly understood in animals. We find that the transcription factor NFAT5 directly senses solution ionic strength using a C-terminal intrinsically disordered region. Both in intact cells and in a purified system, NFAT5 forms dynamic, reversible biomolecular condensates in response to increasing ionic strength. This self-associative property, conserved from insects to mammals, allows NFAT5 to accumulate in the nucleus and activate genes that restore cellular ion content. Mutations that reduce condensation or those that promote aggregation both reduce NFAT5 activity, highlighting the importance of optimally tuned associative interactions. To investigate the composition of NFAT5 condensates in response to hypertonic stress, proteins in close proximity of NFAT5 were identified using a variant of NFAT5 fused to TurboID as bait. Hypertonic stress increases NFAT5 proximity to protein complexes belonging to the GO gene sets of “transcription coactivator activity” and “positive regulation of DNA templated transcription initiation.” Closer inspection revealed that the association between NFAT5 and two transcriptional co-activators (the mediator complex and BRD4) and RNAPII itself increased in response to hypertonic stress.
Project description:The PIK3CA gene is frequently mutated in human cancers. To study the signaling mechanisms responsible for cell growth and invasion phenotypes induced by mutant PIK3CA molecules, we carried out a SILAC-based quantitative phosphoproteomic analysis of MCF10A, a spontaneously immortalized normal mammary epithelial cell line, and two MCF10A knockin cell lines containing different activating mutations of the PIK3CA gene. MCF10A and PIK3CA mutation knock in cells were propagated in DMEM/F12 SILAC media deficient in both L-lysine and L-arginine and supplemented with light lysine (K) and arginine (R) for light, 2H4-K and 13C6-R for medium state and 13C615N2-K and 13C615N4-R for heavy state labeling. Cell lysates were prepared in urea lysis buffer containing 20 mM HEPES pH 8.0, 9 M urea, 1 mM sodium orthovanadate, 2.5 mM sodium pyrophosphate, 1 mM ß-glycerophosphate and 5mM sodium fluoride. The lysates were reduced, alkylated and digested by trypsin. Tryptic peptides were desalted by C18 reverse phase column and followed by strong cation exchange (SCX) fractionation. Fractionated peptides were subjected to TiO2-based phosphopeptide enrichment. LC-MS/MS analysis of enriched phosphopeptides was carried out using a reverse-phase liquid chromatography system interfaced with an LTQ-Orbitrap Velos mass spectrometer. Proteome Discoverer (v 1.3) suite was used for quantitation and database searches. The tandem mass spectrometry data were searched using Mascot (2.2.0) and SEQUEST search algorithms against a Human RefSeq database supplemented with frequently observed contaminants.
Project description:Cross-linking of living cells followed by mass spectrometry identification of cross-linked peptides (in situ CLMS) is an emerging technology to study protein structures in their native environment. One of the inherent difficulties of this approach is the high complexity of the samples following cell lysis. This difficulty largely limits the identification of cross-links to the more abundant proteins in the cell. Here, we describe a targeted approach in which an antibody pulls a specific protein-of-interest out of the lysate. Mass spectrometry analysis of the protein material that binds to the antibody can then identify considerably more cross-links on the antibody target and its interactors. By using an antibody against the CCT chaperonin, we obtained over two hundred cross-links that provide in situ evidence for the subunit arrangement of CCT and its main interactions with prefoldin. Antibodies against tubulin likewise provided in situ evidence for the structure of the microtubule including the seam. Finally, the approach was also successful in identifying cross-links on a protein expressing at very low amounts (tau in non-neuronal cells). These results demonstrate the general applicability of antibody-based sample simplification for in situ CLMS.