One critical task in pluripotent reprogramming is to erase the somatic transcriptional program of starting cells. No strategy or theory exists for achieving erasure of somatic gene expression memory. Here, we present a proof-of-principle strategy in which reprogramming to pluripotency is facilitated by small molecules that erase somatic cell transcription memory. We show that mild chemical targeting of the acetyllysine-binding pockets of the BET bromodomains, the transcriptional bookmarking domains, robustly enhances reprogramming. Furthermore, we show that chemical targeting of the transcriptional bookmarking BET bromodomains dramatically downregulates specific somatic gene expression programs in both naïve and reprogramming fibroblasts. Chemical blocking of the BET bromodomains also resulted in loss of fibroblast morphology early in reprograming. In this study, we experimentally demonstrate a concept for cell fate conversion: facilitating the conversion by chemically targeting the transcriptional bookmarking BET bromodomains responsible for transcriptional memory. Overall design: human BJ cells were treated with JQ1 at 50 nM for 48 hours. Differential expression was compared with DMSO treatment. The same treatments and comparsion were conducted for reprogramming BJ cells, which were transduced with OCT4, SOX2, and KLF4. JQ1iPSC5 is a iPSC (induced pluripotent stem cell) line generated in this study using small molecules JQ1.
Reprogramming by De-bookmarking the Somatic Transcriptional Program through Targeting of BET Bromodomains.
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Hijacking a key chromatin modulator creates epigenetic vulnerability for MYC-driven cancer.
Specimen part, Treatment
View SamplesIt remains unclear how epigenetic modulators impact the tumorigenic potential of Myc. Here we show that the core subunits, including Dpy30, of the major H3K4 methyltransferase complexes are selectively upregulated in Burkitt lymphoma, and Dpy30 is important for efficient genomic binding of Myc. Dpy30 heterozygosity does not affect normal animal physiology, but significantly suppressed lymphomagenesis and reduced expression of a subset of key pro-survival genes when Myc is hyper-activated. Dpy30 heterozygosity also impedes cellular transformation without affecting normal cell growth. These results suggest that Myc hijacks this chromatin modulator to coordinate its oncogenic program for efficient tumorigenesis, meanwhile creating epigenetic vulnerability, which we then exploited by specifically targeting Dpy30s activity to inhibit growth of the Burkitt lymphoma cell model.
Hijacking a key chromatin modulator creates epigenetic vulnerability for MYC-driven cancer.
Specimen part, Treatment
View SamplesWe isolated and characterized mouse neural stem cells that are heterozygous or null for Dgcr8 from E13.5 embryonic brain; Overall design: Examination transcriptional profiles of mouse neural stem cells heterozyous or null for Dgcr8
Canonical microRNAs Enable Differentiation, Protect Against DNA Damage, and Promote Cholesterol Biosynthesis in Neural Stem Cells.
Specimen part, Subject
View SamplesIt is well known that both recipient cells and donor nuclei demonstrate a mitotic advantage as observed in the traditional reprogramming with somatic cell nuclear transfer (SCNT). However, It is not known whether a specific mitotic factor plays a critical role in reprogramming. Here we identify an isoform of human bromodomain-containing 3 (BRD3), BRD3R (BRD3 with Reprogramming activity), as a reprogramming factor. BRD3R positively regulates mitosis during reprogramming, upregulates a large set of mitotic genes at early stages of reprogramming, and associates with mitotic chromatin. Interestingly, a set of the mitotic genes upregulated by BRD3R constitutes a pluripotent molecular signature. The two BRD3 isoforms display differential binding to acetylated histones. Our results suggest a molecular interpretation for the mitotic advantage in reprogramming, and show that mitosis may be a driving force of reprogramming. Overall design: Human BJ cells transduced with lentiviral particles of the conventional reprogramming factors (OCT3/4, SOX2 and KLF4) were used as controls. Two types of controls were used: 1) BJ transduced with OSK (OCT4, SOX2 and KFL4) viruses; 2) BJ cells transduced with OSK plus GFP viruses. Experimental treatment was BJ cells transduced with OSK plus BRD3R viruses. RNA was extracted from cells at day 3 of reprogramming because the reprogramming cells are still homogeneous and transgenes are well expressed at this time point.
The acetyllysine reader BRD3R promotes human nuclear reprogramming and regulates mitosis.
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View SamplesCortical interneurons display a remarkable diversity in their morphology, physiological properties and connectivity. Elucidating the molecular determinants underlying this heterogeneity is essential for understanding interneuron development and function. We discovered that alternative splicing differentially regulates the integration of somatostatin- and parvalbumin-expressing interneurons into nascent cortical circuits through the cell-type specific tailoring of mRNAs. Specifically, we identified a role for the activity-dependent splicing regulator Rbfox1 in the development of cortical interneuron subtype specific efferent connectivity. Our work demonstrates that Rbfox1 mediates largely non-overlapping alternative splicing programs within two distinct but related classes of interneurons. Overall design: RNA-seq of FACS sorted PV+ and SST+ cortical interneuronals at P8 of wt and conditional Rbfox1 Kos
Rbfox1 Mediates Cell-type-Specific Splicing in Cortical Interneurons.
Specimen part, Subject
View SamplesWe previously found that KLF4, a gene highly expressed in adult prostate stem cells, blocks the progression of indolent intraepithelial prostatic lesions into aggressive and rapidly growing tumors. To test whether this anti-cancer effect of KLF4 can also prevent prostate cancer-induced damage to the bone, we ablated KLF4 in human PC3 prostate cancer cells using CRISPR/Cas9-mediated genome editing and compared their behavior to null cells transduced with a DOX inducible KLF4 expression system. KLF4 re-expression inhibited growth of PC3 null cells in monolayer and as colonies in soft agar in a dose-dependent manner. When injected into the mouse femurs, PC3 null cells proliferated rapidly, forming very large, invasive and osteolytic tumors. Induction of KLF4 expression in PC3 null cells immediately after their intra-femoral inoculation blocked the development of tumors while preserving the normal bone architecture. KLF4 re-expression in established PC3 bone tumors inhibited osteolytic effects of PC3 null cells, preventing bone fractures and inducing a significant osteogenic response with regions of new bone formation. Transcriptome analyses of PC3 cells with no or high KLF4 expression revealed KLF4-dependent osteolytic or osteogenic transcriptional programs, respectively. Importantly, these KLF4-dependent functions significantly overlapped with metastatic prostate cancers in patients. Overall design: Uninfected PC3 KLF4 wild-type cells and uninfected PC3 KLF4 null cells were grown for 48 hours and collected for RNA extraction. Another cohort of PC3 KLF4 null cells was infected with lentiviruses expressing a DOX inducible KLF4 expression construct (BFP-T2A-hKLF4) or the control empty vector (BFP-T2A). After 48 hours, DOX (10 ng/ml) was added to the culture medium to induce KLF4 expression. Control and KLF4-overexpressing cells were collected for RNA extraction after a 48-hour incubation with DOX. Total RNA was extracted using the RNeasy kit (Qiagen, CA, USA). RNA-Seq libraries were prepared with the TruSeq sample preparation kit (Illumina, CA, USA).
KLF4 as a rheostat of osteolysis and osteogenesis in prostate tumors in the bone.
Specimen part, Cell line, Treatment, Subject
View SamplesPluripotent stem cells (PSCs) deficient for microRNAs (miRNAs), such as Dgcr8-/- or Dicer-/- embryonic stem cells (ESCs), contain no mature miRNA and cannot differentiate into somatic cells. How miRNA deficiency causes differentiation defects remains poorly understood. Here, we report that miR-302 is sufficient to enable neural differentiation of differentiation-incompetent Dgcr8-/- ESCs. Our data showed that miR-302 directly suppresses the tumor suppressor p53, which is modestly upregulated in Dgcr8-/- ESCs and serves as a barrier restricting neural differentiation. We demonstrated that direct inactivation of p53 by SV40 large T antigen, a short hairpin RNA against Trp53, or genetic ablation of Trp53 in Dgcr8-/- PSCs enables neural differentiation, while activation of p53 by the MDM2 inhibitor nutlin-3a in wild-type ESCs inhibits neural differentiation. Together, we demonstrate that a major function of miRNAs in neural differentiation is suppression of p53 and that modest activation of p53 blocks neural differentiation of miRNA-deficient PSCs.
Elevated p53 Activities Restrict Differentiation Potential of MicroRNA-Deficient Pluripotent Stem Cells.
Specimen part
View SamplesThe ability of breast cancer cells to transiently transition between epithelial and mesenchymal states is critical to complete the metastatic process. In contrast, induction of epithelial-mesenchymal transition (EMT) through the acquisition of drug persistence is a more stable event. Herein, we utilize Her2 transformed human mammary epithelial (HMLE) cells to compare a reversible model of EMT induced by TGF-beta to a stable mesenchymal phenotype induced by chronic exposure to the ErbB kinase inhibitor, lapatinib. Indeed, only a TGF-beta cells capable of returning to an epithelial phenotype resulted in long bone metastasis (BM). These four cell populations were anylzed by RNA sequencing. Overall design: The Her2 transformed HMLE cells are referred to as the parental (Par) cell line and serves as the control. These cells were treated with TGF-beta every three days for a period of 4 weeks to induce EMT (TGFB). Alternatively, the parental cells were treated with 1 micromolar of lapatinib every three days also for 4 weeks and a proliferative drug resistant population (LAPR) emerged. The TGF-beta treated cells were engrafted onto the mammary fatpad and resultant long bone metasases (BM) were isolated and subcluted ex-vivo.
Spleen Tyrosine Kinase-Mediated Autophagy Is Required for Epithelial-Mesenchymal Plasticity and Metastasis in Breast Cancer.
Cell line, Subject
View SamplesThe MUC1 oncoprotein is aberrantly overexpressed in diverse human malignancies including breast and lung cancer. Although MUC1 modulates the activity of several transcription factors, there is no information regarding the effects of MUC1 on global gene expression patterns and the potential role of MUC1-induced genes in predicting outcome for cancer patients. We have developed an experimental model of MUC1-induced transformation that has identified the activation of gene families involved in oncogenesis, angiogenesis and extracellular matrix remodeling. A set of experimentally-derived MUC1-induced genes associated with tumorigenesis was applied to the analysis of breast and lung adenocarcinoma cancer databases. A 35-gene MUC1-induced tumorigenesis signature (MTS) predicts significant decreases in both disease-free and overall survival in patients with breast (n = 295) and lung (n = 442) cancers. The data demonstrate that the MUC1 oncoprotein contributes to the regulation of genes that are highly predictive of clinical outcome in breast and lung cancer patients.
MUC1-induced alterations in a lipid metabolic gene network predict response of human breast cancers to tamoxifen treatment.
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