Project description:To identify substrates of the ubiquitinating E3 enzyme Rsp5 we applied purified Rsp5 to duplicate protein arrays. The Rsp proteins were expressed as fusion proteins to GST. We used as a control Ubr1, a RING domain containing E3 ligase We analyzed Rsp5 from S.cerevisiae on duplicate arrays, with four control chips, two without Rsp5 and two with Ubr1.
Project description:Less than 30% of children with high-risk (HR) metastatic neuroblastoma (NB) show a long survival (Pearson 2000). In order to identify novel molecular prognostic markers useful to better predict patientsM-bM-^@M-^Y relapse risk estimation, we performed genome- and/or transcriptome-wide analyses of 129 stage 4 HR-NBs. This is the largest study for this NB subtype. Children older than 1 year of age at diagnosis were categorized as M-bM-^@M-^\short-survivorsM-bM-^@M-^] (dead of disease within 5 years from diagnosis) and M-bM-^@M-^\long-survivorsM-bM-^@M-^] (alive with an overall survival time > 5 years). A significant correlation of patient survival with the presence of small number of segmental copy number aberrations (CNA < 3) was observed. Thus, within the group of stage 4 HR-NBs, we identified a specific subgroup of patients (those with highest number of CNA) that have a higher risk of progression/recurrence. The complex genomic pattern is an independent prognostic marker, since MYCN oncogene amplification only affects the predictive value of single CNA (i.e., 1p loss, 17q gain). Integrative analysis of genomic and expression signatures demonstrated that fatal outcome is associated with loss of cell cycle control and with progression of tumor due to deregulation of Rho GTPase signaling and genes related to cell motility. Tumors with MYCN amplification showed a lower chromosome instability compared to MYCN-single copy NBs (P=0.0008), dominated by 17q gain and 1p loss. Moreover, our results suggest that the MYCN amplification mainly drives the disruption of neuronal differentiation and the reduction of cell adhesion process involved in tumor invasion and metastasis. For array-CGH profiling, we analyzed 91 samples of metastatic neuroblastomas. All patients were classified as stage 4 and they were older than 1 year of age at time of diagnosis. Regarding the clinical course, 46 were short-survivors (dead of disease within 60 months from diagnosis. Deaths due to toxicity were censored) and 45 were long-survivors (alive with an overall survival time > 60 months). This submission consists of 22 new samples and 69 other cases previously deposited in GEO under Series accessions GSE14109 and GSE25771.
Project description:Serine/threonine kinase 40 (Stk40) was previously identified as a direct target gene of pluripotency-associated transcription factor Oct4 and its overexpression could facilitate differentiation of mouse embryonic stem cells (mESCs) towards the extraembryonic endoderm. Stk40-/- mice are lethal at the perinatal stage, displaying multiple organ failures. However, the molecular mechanisms underlying the physiological functions of Stk40 remain elusive. Here, we report that Stk40 ablation compromises the mesoderm differentiation from mESCs in vitro and in embryos. Mechanistically, Stk40 interacts with both mammalian constitutive photomorphogenic protein 1 (Cop1) and c-Jun, promoting degradation of c-Jun. Consequently, Stk40 knockout leads to c-Jun protein accumulation, which, in turn, might suppress the Wnt signaling activity and impair the mesoderm differentiation process. Overall, this study reveals that Stk40, together with Cop1, represent a novel axis for modulating c-Jun protein levels within an appropriate range during mesoderm differentiation from mESCs. Our finding provides new insight into the molecular mechanism regulating c-Jun protein stability and may have potential for managing related cellular disorders.
Project description:This SuperSeries is composed of the following subset Series: GSE24037: Salivary cytokine alterations in HIV infection part 1 GSE24064: Salivary cytokine alterations in HIV infection part 2 Refer to individual Series
Project description:Alternative splicing (AS) is a key process underlying the expansion of proteomic diversity and the regulation of gene expression. However, the contribution of AS to the control of embryonic stem cell (ESC) pluripotency is not well understood. Here, we identify an evolutionarily conserved ESC-specific AS event that changes the DNA binding preference of the forkhead family transcription factor FOXP1. We show that the ESC-specific isoform of FOXP1 stimulates the expression of transcription factor genes required for pluripotency including OCT4, NANOG, NR5A2 and GDF3, while concomitantly repressing genes required for ESC differentiation. Remarkably, this isoform also promotes the maintenance of ESC pluripotency and the efficient reprogramming of somatic cells to induced pluripotent stem cells. These results reveal an AS switch that plays a pivotal role in the regulation of pluripotency through the control of critical ESC-specific transcriptional programs. Protein binding microarray (PBM) experiments were performed for two isoforms of the DNA binding domain of the human FOXP1 gene. Briefly, the PBMs involved binding GST-tagged DNA-binding proteins to two double-stranded 4*44K Agilent microarrays, each containing a different DeBruijn sequence design, in order to determine their sequence preferences. The method is described in Berger et al., Nature Biotechnology 2006.
Project description:C2H2 zinc fingers (C2H2-ZFs) are the most prevalent type of vertebrate DNA-binding domain, and typically appear in tandem arrays (ZFAs), with sequential C2H2-ZFs each contacting 3 (or more) sequential bases. C2H2-ZFs can be assembled in a modular fashion, providing one explanation for their remarkable evolutionary success. Given a set of modules with defined 3-base specificities, modular assembly also presents a way to construct artificial proteins with specific DNA-binding preferences. However, a recent survey of a large number of three-finger ZFAs engineered by modular assembly reported high failure rates (~70%), casting doubt on the generality of modular assembly. Here, we used protein-binding microarrays to analyze 28 ZFAs that failed in the aforementioned study. Most (17) preferred specific sequences, which in all but one case resembled the intended target sequence. Like natural ZFAs, the engineered ZFAs typically yielded degenerate motifs, binding dozens to hundreds of related individual sequences. Thus, the failure of these proteins in previous assays is not due to lack of sequence-specific DNA-binding activity. Our findings underscore the relevance of individual C2H2-ZF sequence specificities within tandem arrays, and support the general ability of modular assembly to produce ZFAs with sequence-specific DNA-binding activity. Protein binding microarray (PBM) experiments were performed for a set of 20 artificial zinc finger arrays (ZFAs). Briefly, the PBMs involved binding GST-tagged DNA-binding proteins to two double-stranded 44K Agilent microarrays, each containing a different DeBruijn sequence design, in order to determine their sequence preferences. The method is described in Berger et al., Nature Biotechnology 2006.
Project description:In all eukaryotes, histone variants are incorporated into a subset of nucleosomes to create functionally specialized regions of chromatin. One such variant, H2A.Z, replaces histone H2A and is required for viability in all metazoans tested to date. However, the function of H2A.Z in chromatin organization, transcription, and development remains controversialunclear. We mapped the genome-wide distribution of the C. elegans H2A.Z ortholog HTZ-1 during embryogenesis by Chromatin ImmunoPrecipitation on DNA microarrays (ChIP-chip). We find that H2A.Z is incorporated upstream of approximatelybout 25% of C. elegans genes, preferentially upstream of genes required for development and occupied by RNA polymerase II. Fewer sites of HTZ-1 localization occur on the X chromosome relative to autosomes, consistent with the lack of essential genes on X. The data provide evidence for unexpectedly widespread independent regulation of genes within operons. In 37% of operons, HTZ-1 is incorporated upstream of internally encoded genes. In conjunction with ChIP-chip, we used genetic mutation, RNAi, and microscopy to establish that HTZ-1 is present in every cell, and that maternally supplied HTZ-1 is essential for normal development. We interpret these results to indicate that C. elegans HTZ-1 functions in establishing or maintaining an essential chromatin state at promoters regulated dynamically during development. Keywords: chip-chip 4 independent HTZ-1 ChIP biological replicates were performed with 1 dye-swap replicate (ChIP 4). RNA Polymerase II ChIPs were performed from extracts used for HTZ-1 ChIPs 1 and 2 (RNAPII ChIP2 is a dye-swap). HTZ-1, RNA Polymerase II, and no antibody raw intensities Data were normalized by median centering log ratios (IP/input). Normalized Log2 ratios from each experiment were converted to standardized z-scores, array sets were concatenated, and then the median of experiments was taken.
Project description:The Myc-Max heterodimer is a DNA binding protein that regulates expression of a large number of genes. Genome occupancy of Myc-Max is thought to be driven by E-boxes (CACGTG or variants) to which the heterodimer binds in vitro. By analyzing ChIP-Seq datasets, we demonstrated that the positions occupied by Myc-Max across the human genome correlate with the RNA polymerase II (Pol II) transcription machinery better than with E-boxes. Metagene analyses showed that in promoter regions, Myc was uniformly positioned about 100 bp upstream of essentially all promoter proximal paused polymerases with Max about 10 bp upstream of Myc. We re-evaluated the DNA binding properties of full length Myc-Max proteins using electrophoretic mobility shift assays (EMSA) and protein-binding microarrays (PBM). EMSA results demonstrated Myc-Max heterodimers have high affinity for both E-box containing and non-specific DNA. Quantification of the relative affinities of Myc-Max for all possible 8- mers using PBM assays showed that sequences surrounding core 6-mers significantly affect binding. Comparing to the in vitro sequence preferences, Myc-Max genomic occupancy measured by ChIP-Seq was largely, although not completely, independent of sequence specificity. Our results suggest that the transcription machinery and associated promoter accessibility play an important role in genomic occupancy of Myc. Two protein binding microarray (PBM) experiments were performed: one for the heterodimer of the human transcription factors c-Myc and Max, and one for the Max-Max homodimer. Briefly, 4x44K arrays (Agilent Technologies; AmadID 015681) containing the M-bM-^@M-^Xall 10-merM-bM-^@M-^Y universal PBM design were used. Arrays were incubated with a PBS buffer based protein mixture of wither 10nM His-tagged Myc-Max heterodimer or 10nM His-tagged Max-Max homodimer, 2% milk, 200ng/M-BM-5L BSA, 50ng/M-BM-5L Salmon Testes DNA, and 0.02% TX-100. Bound protein was tagged with 10ng/M-BM-5L anti-His antibody conjugated to Alexa 488 (Qiagen; 35310) in PBS with 2% milk. Data were analyzed to obtain fluorescence intensities for all 8mers. The PBM protocol is described in Berger et al., Nature Biotechnology 2006 (PMID 16998473).