Project description:Immunoprecipitation samples were collected using anti-Flag antibody from control vector and Flag-UNC5B-overexpressing HEK293T cells and subjected to mass spectrometry (MS) to identify potential binding partners of UNC5B protein.
Project description:Analysis of RNA binding partners of the post-transcriptional regulator CsrA to translation during exponential growth in Escherichia coli
Project description:RBFOX2 controls the splicing of a large number of transcripts implicated in cell differentiation and development. Parsing RNA-binding protein datasets, we uncover that RBFOX2 can interact with hnRNPC, hnRNPM and SRSF1 to regulate splicing of a broad range of splicing events using different sequence motifs and binding modes. Using immunoprecipitation, specific RBP knockdown, RNA-seq and splice-sensitive PCR, we show that RBFOX2 can target splice sites using three binding configurations: single, multiple or secondary modes. In the single binding mode RBFOX2 is recruited to its target splice sites through a single canonical binding motif, while in the multiple binding mode RBFOX2 binding sites include the adjacent binding of at least one other RNA binding protein partner. Finally, in the secondary binding mode RBFOX2 likely does not bind the RNA directly but is recruited to splice sites lacking its canonical binding motif through the binding of one of its protein partners. These dynamic modes bind distinct sets of transcripts at different positions and distances relative to alternative splice sites explaining the heterogeneity of RBFOX2 targets and splicing outcomes.
Project description:Karyopherin beta 1 (Kpnβ1) is the principal nuclear importer of cargo proteins and plays a role in many cellular processes. Its expression is upregulated in cancer and essential for cancer cell viability, thus the identification of its binding partners might help in the discovery of anti-cancer therapeutic targets and cancer biomarkers. Herein, we applied immunoprecipitation coupled to mass spectrometry (IP- MS) to identify Kpnβ1 binding partners in normal and cancer cells. IP-MS identified 100 potential Kpnβ1 binding partners in non-cancer hTERT-RPE1, 179 in HeLa cervical cancer, 147 in WHCO5 oesophageal cancer and 176 in KYSE30 oesophageal cancer cells, including expected and novel interaction partners. 38 binding proteins were identified in all cell lines, with the majority involved in RNA metabolism. 18 binding proteins were unique to the cancer cells, with many involved in protein translation. Western blot analysis validated the interaction of known and novel binding partners with Kpnβ1 and revealed enriched interactions between Kpnβ1 and select proteins in cancer cells, including proteins involved in cancer development, such as Kpnα2, Ran, Crm1, CCAR1 and FUBP1. Together, this study shows that Kpnβ1 interacts with numerous proteins, and its enhanced interaction with certain proteins in cancer cells likely contributes to the cancer state.
Project description:The main goal of the project was to identify proteins binding to vascular endothelial growth factor receptor 2 (VEGFR2) phosphorylation site Y1173. Synthetic peptides, phosphorylated or not, covering different tyrosine phosphorylation sites in VEGFR2 were immobilized and incubated with cell lysates from human umbilical vein endothelial cells. Retained proteins were analyzed by mass spectrometry. Proteins specifically binding to pY1173 peptide were categorized with regard to the presence of an Src Homology 2 (SH2) domain and the main hits were validated in intact cells treated or not with VEGF, for their ability to bind to the activated wild type VEGFR2 but not to a mutant Y1173F VEGFR2. The role of the pY1173 binding partners in VEGF-regulated endothelial biology was further examined in vitro and in vivo.
Project description:The locations of transcriptional enhancers and promoters were recently mapped in many mammalian cell types. Proteins that bind those regulatory regions can determine cell identity but have not been systematically identified. Here we purify native enhancers, promoters or heterochromatin from embryonic stem cells by chromatin immunoprecipitations (ChIP) for characteristic histone modifications and identify associated proteins using mass spectrometry (MS). 239 factors are identified and predicted to bind enhancers or promoters with different levels of activity, or heterochromatin. Published genome-wide data indicate a high accuracy of location prediction by ChIP-MS. A quarter of the identified factors are important for pluripotency and includes Oct4, Esrrb, Klf5, Mycn and Dppa2, factors that drive reprogramming to pluripotent stem cells. We determined the genome-wide binding sites of Dppa2 and find that Dppa2 operates outside the classical pluripotency network. Our ChIP-MS method provides a detailed read-out of the transcriptional landscape representative of the investigated cell type.
Project description:RNA binding proteins (RBP) have multiple roles associated with mRNA stability and translation. In the Leishmania genus, three Poly(A) Binding Proteins (PABP) were encoded with yet undefined functional distinctions but previous studies of mass-spectrometry identified RBPs differentially associated with PABP1 and PABP2, including RBP23 and DRBD2, respectively. Further characterization of both RBPs were performed through co-immunoprecipitation of proteins with HA-tagged RBP23 and DRBD2 from Leishmania infantum cytoplasmic extract cells, combined to mass spectrometry analysis. The analysis confirmed a strong association between RBP23 and PABP1, as well as with the EIF4E4/EIF4G3, a typical translation initiation complex, while DRBD2 was found to be more associated with PABP2 and a large number of different protein partners. Our studies expand the knowledge about RBPs function and their partners during Leishmania mRNA translation/metabolism.