Here we report the characterization of a novel role for the retinoblastoma protein (pRb) as a regulator of osteoblast adhesion. Abrogation of pRb in osteoblasts resulted in aberrant cadherin expression and loss of adherens junctions. This produced defects suggestive of a transformed phenotype such as impaired cell-to-cell adhesion, loss of contact-dependent growth arrest, and the capacity to evade anoikis. This also resulted in profound abnormalities in bone structure. Consistent with this, microarray analyses showed that pRb regulates a wide repertoire of osteoblast cell adhesion genes. In addition, pRb loss also resulted in altered expression and function of several known regulators of cellular adhesion and adherens junction assembly, such as the Rho GTPase Rac1 and the merlin tumor suppressor. Taken together, our results show that pRb controls cell adhesion by regulating the expression and adherens junction components and by regulating the function of molecules involved in adherens junction assembly and stability.
A role for the retinoblastoma protein as a regulator of mouse osteoblast cell adhesion: implications for osteogenesis and osteosarcoma formation.
Specimen part
View SamplesThe goal of the microarray experiment was to do a head-to-head comparison of the U1 Adaptor technology with siRNA in terms of specificity at the genome-wide level. U1 Adaptors represent a novel gene silencing method that employs a mechanism of action distinct from antisense and RNA interference (RNAi). The U1 Adaptor is a bifunctional oligonucleotide having a Target Domain that is complementary to a site in the target gene's terminal exon and a U1 Domain that binds to the U1 small nuclear RNA (snRNA) component of the U1 small nuclear ribonucleoprotein (U1 snRNP) splicing factor. Tethering of U1 snRNP to the target pre-mRNA inhibits 3' end processing (i.e., polyA tail addition) leading to degradation of that RNA species within the nucleus thereby reducing mRNA levels. We demonstrate that U1 Adaptors can specifically inhibit both reporter and endogenous genes. Further, targeting the same gene either with multiple U1 Adaptors or with U1 Adaptors and small interfering RNAs (siRNAs), strongly enhances gene silencing, the latter as predicted from their distinct mechanisms of action. Such combinatorial targeting requires lower amounts of oligonucleotides to achieve potent silencing.
Gene silencing by synthetic U1 adaptors.
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View SamplesWe recently identified the nonreceptor tyrosine kinase syk as a tumor suppressor in pancreatic ductal adenocarcinoma cells. Reintroduction of syk into Panc1 cells promoted a more differentiated phenotype and retarded invasion and tumorigenic growth. Gene array analysis identified over 2,000 transcripts differentially expressed at FDR<0.01. Among these were members of the MMP2 axis, which were subsequently shown to regulate Panc1 invasion.
Syk tyrosine kinase acts as a pancreatic adenocarcinoma tumor suppressor by regulating cellular growth and invasion.
Cell line
View SamplesAlternative cleavage and polyadenylation (APA) results in mRNA isoforms containing different 3' untranslated regions (3'UTRs) and/or coding sequences. How core cleavage and polyadenylation (C/P) factors regulate APA is not well understood. Using siRNA knockdown coupled with deep sequencing, we found that several C/P factors can play significant roles in 3'UTR-APA. Whereas Pcf11 and Fip1 enhance usage of proximal poly(A) sites (pAs), CFI-25/68, PABPN1, and PABPC1 promote usage of distal pAs. Strong cis element biases were found for pAs regulated by CFI or Fip1, and the distance between pAs plays an important role in APA regulation. In addition, intronic pAs are substantially regulated by splicing factors, with U1 mostly influencing C/P events in 5' introns and U2 impacting those in efficiently spliced introns. Furthermore, PABPN1 regulates expression of transcripts with pAs near the transcription start site, a property possibly related to its role in RNA degradation. Finally, we found that groups of APA events regulated by C/P factors are also modulated in cell differentiation and development with distinct trends. Together, our results indicate that the abundance of different C/P factors and splicing factors plays diverse roles in APA, and is relevant to APA regulation in biological conditions. Overall design: knockdown experiments of 23 C/P factors, 3 splicing factors and U1D in mouse C2C12 myoblast cells
Systematic profiling of poly(A)+ transcripts modulated by core 3' end processing and splicing factors reveals regulatory rules of alternative cleavage and polyadenylation.
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View SamplesTechnical advances have enabled the collection of genome and transcriptome data sets with single-cell resolution. However, single-cell characterization of the epigenome has remained challenging. Furthermore, because cells must be physically separated prior to biochemical processing, conventional single-cell preparatory methods scale linearly. We applied combinatorial cellular indexing to measure chromatin accessibility in thousands of single cells per assay, circumventing the need for compartmentalization of individual cells. We report chromatin accessibility profiles from over 15,000 single cells and use these data to cluster cells on the basis of chromatin accessibility landscapes. We identify modules of coordinately regulated chromatin accessibility at the level of single cells both between and within cell types, with a scalable method that may accelerate progress toward a human cell atlas. Overall design: 3 replicates from GM12878 and HL-60 cell lines collected for differential gene expression analysis.
Multiplex single cell profiling of chromatin accessibility by combinatorial cellular indexing.
No sample metadata fields
View SamplesSkeletal muscle myofibers accrue hundreds of nuclei during post-natal development via fusion with activated satellite cells (myoblasts), which is absolutely reliant on expression of the muscle fusogen myomaker (Mymk) in the myoblasts. Using an inducible genetic approach to render myoblasts non-fusogenic (by tamoxifen-inducible Pax7-CreER mediated recombination of the Mymk gene exclusively in satellite cells), we blocked myonuclear accrual at different time-points of post-natal development and thereby titrated the number of nuclei in resultant mutant myofibers. These Microarray assays were carried out on age day 28 (P28) using total RNA isolated from control and mutant muscle to determine changes in transcriptional profiles of these muscles to (a) assess effects of myonuclear titration, and (b) identify adaptive mechanisms elicited in mutant muscles in response to myonuclear deficiency.
Nuclear numbers in syncytial muscle fibers promote size but limit the development of larger myonuclear domains.
Specimen part
View SamplesLow levels of the cell cycle regulator p27Kip1 are associated with a worse outcome in many tumor types. We report here a new regulatory role of p27Kip1 as a transcriptional regulator. In association with transcriptional factors such as ETS and E2F4 and co-repressors like p130, HDACs and mSin3A, p27 binds to promoters of multiple genes leading to their repression. The p27-target genes participate in RNA processing, translation, respiration and cell cycle. Remarkably, p27-target genes are over-expressed in different human tumors in tight association with a poor clinical prognosis. We also observed a clear correlation between low levels of p27 and over-expression of p27-target genes in tumors. Overall, our findings indicate new tumor suppressor roles of p271 as a transcriptional regulator of genes relevant for oncogenesis.
p27Kip1 represses transcription by direct interaction with p130/E2F4 at the promoters of target genes.
Specimen part
View SamplesCellular responses to carcinogens are typically studied in transformed cell lines, which do not reflect the physiological status of normal tissues. To address this question, we have characterized the transcriptional program and cellular responses of normal human lung WI-38 fibroblasts upon exposure to the ultimate carcinogen benzo[a]pyrene diol epoxide (BPDE). Exposure to BPDE induces a strong inflammatory response in WI-38 primary fibroblasts. Whole-genome microarray analysis shows induction of several genes related to the production of inflammatory factors, including those that encode interleukins (ILs), growth factors, and enzymes related to prostaglandin synthesis and signaling. This is the first demonstration that a strong inflammatory response is triggered in primary fibroblasts in response to a reactive diol epoxide derived from a polycyclic aromatic hydrocarbon.
Benzo[a]pyrene diol epoxide stimulates an inflammatory response in normal human lung fibroblasts through a p53 and JNK mediated pathway.
Specimen part
View SamplesMost differentiation protocols for generation of hepatocyte-like cells from iPS cells generate cells with heterogenous expression of hepatic markers, which confounds results from liver disease models involving complex traits and subtle phenotypes
Mapping the Cell-Surface N-Glycoproteome of Human Hepatocytes Reveals Markers for Selecting a Homogeneous Population of iPSC-Derived Hepatocytes.
Specimen part
View SamplesMating triggers physiological and behavioral changes in females.
Mating induces an immune response and developmental switch in the Drosophila oviduct.
No sample metadata fields
View Samples