Project description:Lmx1b regulates dorsalization of limb fates, but the mechanism of this regulation has not been characterized. To identify candidate genes regulated by Lmx1b we compared the limbs from Lmx1b KO mice to wild type mice during limb dorsalization (e11.5-13.5). Differentially expressed genes that we common to all three stages examined were considered to be likely candidates for Lmx1b regulation and further evaluated. At 11.5 and 12.5 dpc, embryos were harvested and the limb buds with the limb girdles were isolated. Embryos at 13.5dpc were also harvested and their distal limb buds (zeugopods and autopods) were isolated. Embryos were genotyped to confirm Lmx1b homozygosity (-/- or +/+). RNA from embryonic forelimbs and hindlimbs of wild type (WT) and Lmx1b KO mice was harvested using the Rneasy Kit (Qiagen). RNA was pooled to decrease genetic variability, i.e., six limbs at 11.5 dpc, three limbs at 12.5 dpc and six limbs at 13.5 dpc. Duplicate samples were generated using different embryos for each stage and then hybridized to the Affymetrix GeneChip® Mouse Genome 430 2.0 Array (UCI, Irvine, CA).
Project description:Lmx1b is a homeodomain transcription factor responsible for limb dorsalization. Despite striking double-ventral (loss-of-function) and double-dorsal (gain-of-function) limb phenotypes, no direct downstream gene targets in the limb have been confirmed. To determine direct targets of Lmx1b during limb dorsalization (E12.5), we performed chromatin immunoprecipitation followed by next generation sequencing (ChIP-seq). Nearly 84% (n=617) of the Lmx1b-bound genomic fragments or intervals (LBIs) identified by two Lmx1b-ChIP-seqs overlap with chromatin regulatory marks indicative of potential cis-regulatory modules (PCRMs). In addition, 73 LBIs mapped to known cis-regulatory modules (CRMs) active during limb development. We compared Lmx1b-bound PCRMs to genes differentially expressed by Lmx1b at E12.5 and found 292 PCRMs within 1 Mb of 254 Lmx1b-regulated genes. Gene ontology analysis of these associated genes suggests that Lmx1b mediates dorsalization through the regulation of extracellular matrix production, bone/joint formation, axonal guidance, vascular development, cell proliferation and cell movement. We validated the functional activity of 2 PCRMs associated to Lmx1b-regulated genes, demonstrating activity and overlap with the associated gene during limb development. This is the first report to describe the genome-wide distribution of Lmx1b binding during limb development, directly linking Lmx1b to targets that accomplish limb dorsalization.
Project description:A control vs. genetic knockout experiment aimed at determining what RNAs are upregulated or downregulated in e11.5 mouse proximal limb tissue lacking the Lmx1b gene. Because Lmx1b is required for dorsal-ventral patterning of the limb, this screen gives insight into what putative downstream targets of Lmx1b contribute to dorsal-ventral patterning. Experiment Overall Design: The proximal portion of e11.5 hindlimb buds (~500um) was used for RNA extraction. Each array was hybridized with pooled cRNAs from both hindlimb buds of three embryos (6 hindlimbs/sample).
Project description:Heart valve formation initiates when endothelial cells of the heart transform into mesenchyme and populate the cardiac cushions. The transcription factor, SOX9, is highly expressed in the cardiac cushion mesenchyme, and is essential for heart valve development. Loss of Sox9 in mouse cardiac cushion mesenchyme alters cell proliferation, embryonic survival, and disrupts valve formation. Despite this important role, little is known regarding how SOX9 regulates heart valve formation or its transcriptional targets. Therefore, we mapped putative SOX9 binding sites by ChIP-Seq in embryonic day (E) 12.5 heart valves, a stage at which the valve mesenchyme is actively proliferating and initiating differentiation. Embryonic heart valves have been shown to express a high number of genes that are associated with chondrogenesis, including several extracellular matrix proteins and transcription factors that regulate chondrogenesis. Consequently, we compared regions of putative SOX9 DNA-binding between E12.5 heart valves and E12.5 limb buds. We identified context-dependent and contextâindependent SOX9 interacting regions throughout the genome. Analysis of context-independent SOX9 binding suggests an extensive role for SOX9 across tissues in regulating proliferation-associated genes including key components of the AP-1 complex. Integrative analysis of tissue-specific SOX9 interacting regions and gene expression profiles on Sox9-deficient heart valves demonstrated that SOX9 controls the expression of several transcription factors with previously identified roles in heart valve development, including Twist1, Sox4, Mecom/Evi1 and Pitx2. Together, our data identifies SOX9 coordinated transcriptional hierarchies that control cell proliferation and differentiation during valve formation. Examination of SOX9 binding sites in E12.5 atrioventricular canal (AVC) and E12.5 embryonic limb and mRNA expression profiling in E12.5 WT and Sox9 mutant AVCs, in duplicate.
Project description:To identify genes regulated by Pitx1 during early hindlimb development, we compared gene expression differences between hindlimb buds from E12.5 Pitx1+/+ and Pitx1-/- mice on the Illumina MouseRef-8 expression Bead Chip. Genes involved in muscle development GeneGO processes were highly enriched in our dataset, specifically in down-regulated genes. This data is consistent with the reduced muscle volumes that were observed in the clubfoot limbs of our adult mice. Hindlimb buds were collected from Pitx1+/- mated mice at embryonic day E12.5 and genotypes were determined by PCR of DNA isolated from tails.
Project description:The transcriptome of mouse limb buds of Shh mutant embryos was compared to the transcriptome of limb buds of wild type embryos at embryonic day E10.5
Project description:H3K9me3 ChIP-seq on embryonic 12.5 day mouse limb For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODE_Data_Use_Policy_for_External_Users_03-07-14.pdf
Project description:H3K9ac ChIP-seq on embryonic 12.5 day mouse limb For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODE_Data_Use_Policy_for_External_Users_03-07-14.pdf
Project description:H3K4me2 ChIP-seq on embryonic 12.5 day mouse limb For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODE_Data_Use_Policy_for_External_Users_03-07-14.pdf
Project description:H3K4me3 ChIP-seq on embryonic 12.5 day mouse limb For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODE_Data_Use_Policy_for_External_Users_03-07-14.pdf