Project description:Wild type and Dicer null embryonic mouse limbs were analaysed using Affymetrix arrays to identify gene expression changes. Genes that were up-regulated in Dicer-null limbs were canidates for being miRNA targets. Potential miRNA target genes were validated using qRTPCR. Mice carrying a heterozygous Dicer floxed allele and the prxcre driver allele were crossed to homozygous Dicer Floxed mice. Embryos were harvested from pregent moms and genotyped to determine heterozygous, Wild type and mutant limb buds. These limb buds were used to prepare RNA for array analysis.
Project description:Multiple genes are dysregulated in hindlimb buds of Nipbl-deficient embryos. In all, more than 1000 limb bud genes were found to be significantly altered in expression by microarray analysis of E10.5 mouse hindlimb buds. Small changes in expression (mostly decreases) were observed for genes involved in FGF, BMP, and SHH pathways, as well as numerous genes involved in the Wnt/planar cell polarity signaling pathway. Genes involved in the Mediator complex, Cohesin function, and Hox gene expression and functions were also dysregulated in Nipbl deficient limb buds. Microarray analysis using RNA extracted from E10.5 hindlimb limb buds harvested from stage-matched Nipbl+/- (n=12) and wildtype (n=12)
Project description:Multiple genes are dysregulated in hindlimb buds of Nipbl-deficient embryos. In all, more than 1000 limb bud genes were found to be significantly altered in expression by microarray analysis of E10.5 mouse hindlimb buds. Small changes in expression (mostly decreases) were observed for genes involved in FGF, BMP, and SHH pathways, as well as numerous genes involved in the Wnt/planar cell polarity signaling pathway. Genes involved in the Mediator complex, Cohesin function, and Hox gene expression and functions were also dysregulated in Nipbl deficient limb buds.
Project description:The combinatorial expression of the Hox genes along the body axes, referred to as the HOX code, is a major determinant of cell fate and plays a prevailing role in generating the animal body plan. In developing limb buds, the paralogous group 13 genes of the HoxA and HoxD clusters are essential for patterning the distal-most limb structures, the digits. Inactivation of HOXA13 and HOXD13 transcription factors (HOX13) leads to complete digit agenesis in mice, but how HOX13 regulate transcriptional outcomes and confer identity to the distal-most limb cells has remained elusive. Here we performed genome-wide profiling of HOX13 by chromatin immunoprecipitation and analyzed the transcriptome and chromatin state of wild type early and late-distal limb buds, as well as Hoxa13-/-;Hoxd13-/- compound mutant limb buds. Our results show that inactivation of HOX13 impairs the activation and repression of putative cis-regulatory modules specific to the late-distal limb cells. Loss of HOX13 also disrupts the specific, spatial patterning of gene expression along the proximal-distal axis of the developing limb buds. These results show that proper termination of the early limb transcriptional program and activation of the late-distal limb program are coordinated by the dual action of HOX13 on cis-regulatory modules.
Project description:The combinatorial expression of the Hox genes along the body axes, referred to as the HOX code, is a major determinant of cell fate and plays a prevailing role in generating the animal body plan. In developing limb buds, the paralogous group 13 genes of the HoxA and HoxD clusters are essential for patterning the distal-most limb structures, the digits. Inactivation of HOXA13 and HOXD13 transcription factors (HOX13) leads to complete digit agenesis in mice, but how HOX13 regulate transcriptional outcomes and confer identity to the distal-most limb cells has remained elusive. Here we performed genome-wide profiling of HOX13 by chromatin immunoprecipitation and analyzed the transcriptome and chromatin state of wild type early and late-distal limb buds, as well as Hoxa13-/-;Hoxd13-/- compound mutant limb buds. Our results show that inactivation of HOX13 impairs the activation and repression of putative cis-regulatory modules specific to the late-distal limb cells. Loss of HOX13 also disrupts the specific, spatial patterning of gene expression along the proximal-distal axis of the developing limb buds. These results show that proper termination of the early limb transcriptional program and activation of the late-distal limb program are coordinated by the dual action of HOX13 on cis-regulatory modules.
Project description:The basic helix-loop-helix transcription factor Twist1 has a well-documented role in mesenchymal populations of the developing embryo, such as endocardial cushion (ECC) mesenchymal cells and limb buds, and during cancer development and progression. Whether Twist1 regulates the same transcriptional targets in different cell types has yet to be investigated. Through chromatin immunoprecipitation followed by sequencing (Chip-seq) analysis, the cell type-specific genome-wide occupancy of Twist1 was investigated in ECCs, limb buds and mouse peripheral nerve sheath tumor (PNST) cells. Twist1 binds mainly in a cell type-specific manner, with very few common genomic regions occupied by Twist1 in different cell types. Genes associated with binding peaks in each cell type are related to known Twist1 cellular functions in ECCs, limb buds, and cancer cells. We found that cell type-specific binding of Twist1 may be influenced by histone modifications or co-factors. Binding regions were located in several Wnt pathway associated genes, supporting a link between Twist1 and Wnt signalling in ECCs, limb buds, and PNST cells. These data suggest that similar functions are regulated by Twist1 in ECCs, limb buds, and PNST cells in a cell type-specific manner, and provide insights into possible mechanisms utilized for cell type-specificity of Twist1 binding. We compare Twist1 genome occupancy in mouse embryonic day (E) 12.5 endocardial cushion mesenchymal cells, E10.5 forelimb buds, and a mouse peripheral nerve sheath tumor cell line.
Project description:We used the RCAS avian retrovirus to overexpress SOCS2 in the developing chicken limb buds and transcriptome sequencing (mRNA-Seq) revealed changes in expression of genes known to be associated with growth and development in forelimbs with overexpressed SOCS2.
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: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).