Project description:The small heat shock protein Hsp27 has been long demonstrated as a major driver of Castration Resistant Prostate Cancer (CRPC) progression via an androgen receptor-independent pathway. In the light of identification of its molecular mechanisms, we found that the RNA helicase protein DDX5 was an interactor of Hsp27 and DDX5 expression was regulated by Hsp27 through its cytoprotective function. We showed that DDX5 was overexpressed in a large collection of human samples in aggressive PCs, especially CRPC. Here, we described the protein-protein interaction network of DDX5 which were identified in four human prostate cell lines (PNT1A, LNCaP, DU-145 and PC-3) representing different disease stages using immunoaffinity purification and quantitative mass spectrometry. The DDX5 interactome in CRPC cells was enriched in several functions (DNA damage response, translation, transcription, RNA stability, and DNA conformation changes) involved in disease progression. Furthermore, we found a new critical function of DDX5 in DNA damage repair in CRPC and validated the interaction of DDX5 with the DNA repair complex Ku70/Ku86 which plays a pivotal role in the NHEJ process. We also showed that DDX5 overexpression conferred resistance to DNA damage poisoners (such as irradiation and cisplatin) in CRPC, a feature that could lead to genome maintenance, tumor progression and treatment resistance.
Project description:Extracellular vesicles (EVs) are present in all body fluids. Shed by cells, their molecular make-up reflects that of their cell of origin and/or tissue pathological situation. Our working hypothesis was that analyzing the protein composition, protein abundance, and functional clustering of EVs released by peritoneal exudate cells (PECs) in the pristane experimental lupus model would allow us to identify predictive or diagnostic biomarkers that might discriminate the autoimmunity process in lupus from inflammatory reactions and/or normal physiological processes. Three pools of PE-EVs were isolated from pristane-treated mice (WT versus Cd38-/- mice) by qEV size exclusion column methodology (F5-12, F5-10 and F11-12). Protein extracts were analyzed by LC-MS/MS. Protein identification was performed with ProteinScape, and MASCOT data searching using Swiss-Prot database. For relative quantification the emPAI-based method was used. The functional enrichment analysis was based on the latest publicly available data from multiple annotation and ontology resources that can be automatically accessed through ClueGO + CluePedia apps within Cytoscape environment. STRING app and EnrichR tools were also used. Gene Ontology (GO) and signaling pathways enrichment analyses of F5-10 and F11-12 PE-EVs via ClueGO analyses showed that the proteins clustered in functionally distinct GO terms and signaling pathways. Moreover, the predominance of given GO terms in PE-EVs seemed to vary with the extent of the inflammatory/autoimmune reaction to pristane. Compared with the protein content and protein abundance in PECs (mainly Ly6Chi inflammatory monocytes and neutrophils), PE-EVs showed an enrichment in neutrophil-associated functions, in particular in PE-EVs from Cd38-/- mice.
Project description:Identifying the proteins associated with the polyribosomes in astrocytes from the mouse brain to unveil translation regulation mechanisms in these cells.
Project description:CCCTC-binding factor (CTCF) is a DNA-binding protein that plays important roles in chromatin organization, though the mechanism by which CTCF carries out these functions is not fully understood. Recent studies show that CTCF recruits the cohesin complex to insulator sites and that cohesin is required for insulator activity. Here we have shown that the DEAD box RNA helicase p68 (DDX5) and its associated noncoding RNA, steroid receptor RNA activator (SRA), form a complex with CTCF that is essential for insulator function. p68 was detected at CTCF sites in the IGF2/H19 imprinted control region (ICR) as well as other genomic CTCF sites. In vivo depletion of SRA or p68 reduced CTCF-mediated insulator activity at the IGF2/H19 ICR, increased levels of IGF2 expression, and increased interactions between the endodermal enhancer and IGF2 promoter. p68/SRA also interacts with members of the cohesin complex. Depletion of either p68 or SRA does not affect CTCF binding to its genomic sites, but it does reduce cohesin binding. The results suggest that p68/SRA stabilizes the interaction of cohesin with CTCF, by binding to both, and is required for proper insulator function. Identification of p68-binding sites in Hela cells using ChIP-Seq.
Project description:Ddx5 inhibition in RN2 cells slows cell proliferation and induces apoptosis within 48-72hrs. The aim of this analysis was to gain insight into how Ddx5 inhibition causes this outcome by analyzing gene expression changes in RN2 cells that occur at early timepoints after Ddx5 inhibition that precedes the timepoint when RN2 proliferation/cell death becomes evident in tissue culture (72hrs after inhibition). Derivatives of RN2 AML cells were prepared that encode doxycycline-inducible expression of either of two different shRNAs targeting Ddx5 (shDdx5.1322 and shDdx5.2086) or a negative control shRNA that targets Renilla Luciferase (shRen.713). Six independent cultures of each derivative RN2 cell line (shDdx5.1322, shDdx5.2086, or shRen.713) were treated with doxycycline at timepoint 0 days to induce expression of the indicated shRNA in the RN2 cells. Each shRNA is co-expressed with dsRed in a doxycycline-induced manner and flow cytometry analysis indicated that doxycycline induced expression of dsRed and the shRNA in 70-to-80% of the cells in each culture. RNA was isolated from three independent cultures of each derivative RN2 cell line at either 24hrs and 48hrs after dpxycycline treatment. Therefore this study consists of 18 samples, sequencing results from biological triplicate samples of RN2-shDdx5.1322, RN2-shDdx5.2086, and RN2-shRen.713 at 24hrs post-doxycycline and sequencing results from biological triplicate samples of RN2-shDdx5.1322, RN2-shDdx5.2086, and shRen.713 at 48hrs post-doxycycline.
Project description:DNA methylation is an epigenetic modification that specifies the basic state of pluripotent stem cells and regulates the developmental transition from stem cells to various cell types. In flowering plants, the shoot apical meristem (SAM) contains a pluripotent stem cell population which generates the aerial part of plants including the germ cells. Under appropriate conditions, the SAM undergoes a developmental transition from a leaf-forming vegetative SAM to an inflorescence- and flower-forming reproductive SAM. While SAM characteristics are largely altered in this transition, the complete picture of DNA methylation remains elusive. Here, by analyzing whole-genome DNA methylation of isolated rice SAMs in the vegetative and reproductive stages, we found that methylation at CHH sites is kept high, particularly at transposable elements (TEs), in the vegetative SAM relative to the differentiated leaf, and increases in the reproductive SAM via the RNA-dependent DNA methylation pathway. We also found that half of the TEs that were highly methylated in gametes had already undergone CHH hypermethylation in the SAM. Our results indicate that changes in DNA methylation begin in the SAM long before germ cell differentiation to protect the genome from harmful TEs.
Project description:RNA helicases DDX5 and DDX17 are members of a large family of highly conserved proteins involved in gene expression regulation, although their in vivo targets and activities in biological processes like cell differentiation, that requires reprogramming of gene expression programs at multiple levels, are not well characterized. In this report, we uncovered a new mechanism by which DDX5 and DDX17 cooperate with hnRNP H/F splicing factors to define epithelial- and myoblast-specific splicing subprograms. We next observed that downregulation of DDX5 and DDX17 protein expression during epithelial to mesenchymal transdifferentiation and during myogenesis contributes to switching splicing programs during these processes. Remarkably, this downregulation is mediated by the production of microRNAs induced upon differentiation in a DDX5/DDX17-dependent manner. Since DDX5 and DDX17 also function as coregulators of master transcriptional regulators of differentiation, we propose to name these proteins M-bM-^@M-^\master orchestratorsM-bM-^@M-^] of differentiation, that dynamically orchestrate several layers of gene expression. 6 samples of MCF7 cells exposed to different treatments were analyzed: 3 x siCTRLM-BM- ; 3 x si(DDX5-17) AND 6 samples of MCF10 cells exposed to different treatments were analyzed: 3 x siCTRLM-BM- ; 3 x si(DDX5-17)
Project description:Starting from the structure of the human ASF1-histone complex, we developed a rational design strategy combining epitope tethering and optimization of interface contacts to identify a potent peptide inhibitor with a dissociation constant of 3 nM. LC-MS/MS was used to identify in vivo targets of the most prominent peptide inhibitor.
Project description:Rett syndrome is a complex neurodevelopmental disorder that is mainly caused by mutations in MECP2. However, mutations in FOXG1 cause a less frequent non-congenital form called atypical Rett syndrome. FOXG1 is a key transcription factor implicated in forebrain development, where it maintains the balance between progenitor proliferation and neuronal differentiation. Using SILAC based quantitative proteomics and genome-wide small RNA sequencing, we identified that FOXG1 interacts with the ATP-dependent RNA helicase, DDX5/p68 and controls the biogenesis of miRNAs. Both, FOXG1 and DDX5 bind to the miR200b/a/429 primary transcript and associate with the microprocessor complex, whereby DDX5 recruits FOXG1 to DROSHA. In vivo and in vitro experiments show that both FOXG1 and DDX5 are necessary for effective maturation of miR200b/a/429. RNAseq analyses of Foxg1-heterozygote hippocampi and miR200b/a/429 overexpressing Neuro-2a cells revealed that the cAMP-dependent protein kinase type II-beta regulatory subunit (PRKAR2B) is a target of miR200 in neural cells. Since it is known that PRKAR2B inhibits postsynaptic functions by attenuating protein kinase A (PKA) activity, increased PRKAR2B levels may contribute to neuronal dysfunctions in FOXG1 Rett syndrome.