Project description:PIWI-interacting RNAs (piRNAs) guide PIWI proteins to suppress transposable elements in animal gonads. Here we demonstrate that in the mouse embryonic male germline, endonucleolytic cleavage (slicing) of a transcript by cytosolic MILI acts as a trigger to initiate its further 5??3? processing into non-overlapping fragments. These fragments accumulate as new piRNAs within the nuclear PIWI protein MIWI2. We identify Exonuclease domain-containing 1 (EXD1) as a partner of the established MIWI2 piRNA biogenesis factor TDRD12. Although EXD1 homodimers are inactive as a nuclease, it functions as an RNA adapter within a PET (PIWI-EXD1-Tdrd12) complex. Loss of Exd1 impacts biogenesis of MIWI2 piRNAs and displays a reduction in sequences generated by MILI slicing. This results in selective depletion of repeat piRNAs that target active retrotransposons like LINE1, which are de-repressed in the mutant. We propose that PIWI slicing and EXD1 promote coordination of nucleo-cytoplasmic silencing via piRNA biogenesis. Immunoprecipitated or total small RNAs were purified and sequenced from P0 mouse testis of Exd1+/- and Exd1 -/- mice. Testes of three males were pooled together and MILI and MIWI2 immunoprecipitation was performed or total small RNAs were purified. Two replicas from different pools were prepared. For Rosa26-pi reporter mouse P0 testes of three males were pooled together and MILI and MIWI2 immunoprecipitation was performed.
Project description:Pluripotency can be induced in murine and human fibroblast by transduction of four transcription factors (Oct4, Sox2, Klf4 and c-Myc). Previously we reported that two factors (Oct4 and Klf4) are sufficient for reprogramming adult mouse neural stem cells (NSCs) to a pluripotent state. However, although NSCs endogenously express the factors Sox2, c-Myc, and Klf4, our previous report does not elucidate why exogenous expression of either Klf4 or c-Myc is still required for reprogramming. Here we report that exogenous expression of Oct4 is sufficient to generate one-factor induced pluripotent stem (1F iPS) cells without any oncogenic factors, such as c-Myc and Klf4, from mouse adult NSCs, which endogenously express Sox2, c-Myc, and Klf4, and also intermediate reprogramming markers alkaline phosphatase (AP), stage-specific embryonic antigen-1 (SSEA-1). These results extend our previous report proposing that somatic cells can be reprogrammed to a pluripotent state with a reducing number of reprogramming factors when the complementing factors are endogenously expressed in the somatic cells. Experiment Overall Design: 10 hybridizations in total. Experiment Overall Design: NSC-derived iPS cells by one-factor (Oct4) in triplicate: Experiment Overall Design: - NSC_1F_iPS_1 Experiment Overall Design: - NSC_1F_iPS_2 Experiment Overall Design: - NSC_1F_iPS_3 Experiment Overall Design: One-factor (Oct4) iPS cell-derived NSC in triplicate: Experiment Overall Design: - 1F_iPS_NSC_1 Experiment Overall Design: - 1F_iPS_NSC_2 Experiment Overall Design: - 1F_iPS_NSC_3 Experiment Overall Design: Neural stem cell (NSC) derived from brain of OG2/Rosa26 mice: Experiment Overall Design: - NSC_1 Experiment Overall Design: - NSC_2 Experiment Overall Design: - NSC_3 Experiment Overall Design: - NSC_4
Project description:Approximately 60-70% of patients with 22q11.2 deletion syndrome (22q11.2DS; velo-cardio-facial syndrome/DiGeorge syndrome) have cardiac outflow tract anomalies including persistent truncus arteriosus (PTA) as the most severe defect. Among the genes in the 22q11.2 region, TBX1, encoding a T-box transcription factor is a major candidate for cardiovascular malformations and its inactivation in mice results in a PTA. To identify novel signaling mechanisms that function downstream, we found that Tbx1 restricts canonical Wnt signaling in the pharyngeal apparatus. To test for tissue specificity within the pharyngeal apparatus, we inactivated Tbx1 in the anterior portion of the secondary heart field (AHF) mesoderm using the Mef2c-AHF-Cre allele and observed a full penetrant PTA (n = 30). Tbx1 promotes progenitor cells but restricts differentiation whereas Wnt signaling, in the AHF, promotes cardiomyocyte differentiation. To determine whether Tbx1 and canonical Wnt signaling act in opposing pathways, both alleles of Tbx1 and one β-catenin allele were inactivated in the AHF and 85% of them (n = 35) showed partial or complete rescue. The antagonistic function of the two pathways was further confirmed by gene expression profiling, indicating that these two pathways provide a key balance in the AHF to prevent premature differentiation of progenitor cells prior to reaching the cardiac outflow tract. We inactivatedTbx1 and beta-catenin allele to identify function of Tbx1 and beta-catenin in the anterior portion of the secondary heart field (AHF) mesoderm. We also inactivated both alleles of Tbx1 and one β-catenin alleles (rescue design) to determine whether Tbx1 and canonical Wnt signaling act in opposing pathways
Project description:A reporter transgene displayed parental imprinting in mouse embryos when positioned into the Itga6 gene. The strong lacZ pattern of expression scored in embryos inheriting the transgene from a male was not present when transmitted from a female. The transgene exhibited maternal allele-specific DNA hyper-methylation acquired in the germ-line and histone modifications corresponded to profiles described at known imprinted loci. Chromosome conformation analyzes revealed distinct, parent-of-origin interaction domains, with a more compact structure characterizing the maternally inherited repressed allele. The analysis of such transgene insertions with a selective potential to induce imprinting may help understanding the mechanisms identifying particular loci as targets for allele-specific repression. Data were quantile normalized within 4C/input replicate groups and scaled to medial feature intensity of 100 using TAS software (Affymetrix), generating signal.bar files. For each genomic position, a data set was generated consisting of all (PM-MM) pairs mapping within a sliding window of 250 bp. For Inv(rel5-Itga6) tissues, two independent 4C experiments were performed and merged in the .bar file.
Project description:Reprogramming of somatic cells is a valuable tool to understand the mechanisms of regaining pluripotency and further opens up the possibility to generate patient-specific pluripotent stem cells. Reprogramming of mouse and human somatic cells into pluripotent stem cells, designated as induced pluripotent stem (iPS) cells, has been possible with the expression of the transcription factor quartet Oct4, Sox2, c-Myc, and Klf4. Considering that ectopic expression of c-Myc causes tumourigenicity in offspring and retroviruses themselves can cause insertional mutagenesis, the generation of iPS cells with a minimal number of factors may hasten the clinical application of this approach. Here, we show that adult mouse neural stem cells (NSCs) express higher endogenous levels of Sox2 and c-Myc than ES cells and that exogenous Oct4 together with either Klf4 or c-Myc are sufficient to generate iPS cells from NSCs. These two-factor (2F) iPS cells are similar to embryonic stem cells at the molecular level, contribute to development of the germline, and form chimeras. We propose that, in inducing pluripotency, the number of reprogramming factors can be reduced when using somatic cells that endogenously express appropriate levels of complementing factors. Experiment Overall Design: 8 hybridizations in total. Experiment Overall Design: NSC derived iPS cells by 2 factors (Oct4 and Klf4) in triplicate: Experiment Overall Design: - iPS cell_2F_1 Experiment Overall Design: - iPS cell_2F_2 Experiment Overall Design: - iPS cell_2F_3 Experiment Overall Design: Embryonic Stem cells (ESC) in triplicate: Experiment Overall Design: - ESC_1 Experiment Overall Design: - ESC_2 Experiment Overall Design: - ESC_3 Experiment Overall Design: NSC cultures in duplicates: Experiment Overall Design: - NSC_2 Experiment Overall Design: - NSC_3 Experiment Overall Design: NSC derived iPS cells by 4 factors (Oct4, Sox2, c-Myc and Klf4) in triplicate: Experiment Overall Design: - iPS cell_4F_1 Experiment Overall Design: - iPS cell_4F_2 Experiment Overall Design: - iPS cell_4F_3
Project description:MicroRNAs are a class of short ~22 nucleotide RNAs predicted to regulate nearly half of all protein-coding genes, including many involved in basal cellular processes and organismal development. Although both increases and decreases in the levels of specific miRNAs have been shown to promote tumor development, a global reduction in miRNAs is commonly observed in various human tumors. However, complete loss has not been documented, suggesting an essential function for miRNAs in tumorigenesis. Here we present the finding that transformed or immortalized Dicer-null somatic cells can be isolated readily in vitro, maintain the characteristics of Dicer-expressing controls and remain stably proliferative. Furthermore, Dicer-null cells from a sarcoma cell line, though depleted of miRNAs, are competent for tumor formation. Hence, miRNA levels in cancer may be maintained in vivo by a complex stabilizing selection in the intratumoral environment. Small RNAs from tumor cell lines (murine sarcoma KrasG12D, p53 -/-) with and without Dicer (Dicer f/-, Dicer -/-) were analyzed.
Project description:KMT2D is required in the cardiac mesoderm, anterior heart field precursors and cardiomyocytes. Kmt2d deletion in cardiac mesoderm (Mesp1Cre) is embryonic lethal at E10.5 and mutants have hypoplastic hearts; Kmt2d deletion in anterior heart field precursors (Mef2cAHF::Cre) deletion is embryonic lethal at E13.5 and mutants have defects in septation of outflow tract and interventricular septum (IVS); Kmt2d deletion in cardiomyocytes (Tnnt2::Cre) deletion is embryonic lethal at E14.5 and mutants have defects in IVS septation and compact myocardium. The goal of this study is to compare changes in gene expression in these Kmt2d conditional deletion mutants and understand common or distinct pathways dysregulated in absence of KMT2D. Whole genome gene expression analysis was performed on RNA isolated from control and mutant embryonic hearts (or right ventricles and outflow tract for anterior heart field deletion samples). Libraries were prepared using Illumina TruSeq Paired-End Cluster Kit v3, and sequenced with the Illumina HiSeq 2500 system for pair-ended 100 base pairs (PE 100 bp).
Project description:The goal of this study was to analyze global gene expression in specific populations of nociceptor sensory neurons, the neurons that detect damaging/noxious stimuli. The dorsal root ganglia (DRG), trigeminal ganglia, and nodose ganglia are anatomically distinct peripheral sensory ganglia that contain nociceptors which innervate skin, gut, lungs, and other distinct organ tissues. We used flow cytometry to purify nociceptors from these ganglia and profiled their global gene expression signatures to compare gene expression between these different anatomically distinct nociceptors. Nav1.8-Cre were bred with Rosa26-TdTomato to generate Nav1.8-Cre/R26-TdTomato reporter progeny, where all peripheral nociceptor neurons are genetically marked with red fluroescence due to specific expression of the TTX- resistant sodium channel Nav1.8. Lumbar region dorsal root ganglia (DRG), trigeminal ganglia, and nodose ganglia were dissected from mice (3 mice were pooled/sample). Highly red fluorescent neurons were Facs purified, RNA extracted, and processed for microarray analysis.
Project description:Programmed ribosomal frameshifting is a process that augments the coding capacity of particular mRNA transcripts. Programmed ribosomal frameshifting may occur during the decoding of chromosomally encoded genes in both prokaryotes and eukaryotes. Although programmed ribosomal frameshifting has been intensively studied, less is known about the occurrence of translation errors that result in frameshifts. Detection of unexpectedly efficient frameshift suppression in E. coli (at levels ranging from 1% to 10% with two unrelated test proteins) led us to investigate the scope of events responsible for restoration of the native frame. To enable a comprehensive approach, we developed a targeted mass-spectrometry method–“translational tiling proteomics”–allowing interrogation of the full set of possible –1 slippage events that could lead to the observed instances of frameshift suppression in vitro and in cells. Our findings point to an unexpectedly high basal level of ribosomal frameshifting, suggest that frameshifted products may contribute more significantly to the proteome than generally assumed, and raise the possibility that particular pseudogenes may specify functional proteins.
Project description:Two separate pools of three Flox or two Lrh1t-/- pancreas RNA preparations was subjected to the Illumina RNA-seq protocol. Examination of mRNA levels in induced Lrh1 pancreas knockout and wild-type mice.