ABSTRACT: We have used DGE-SAGE, a digital transcriptomics tool, to determine the expression profile of E14.5 mouse forelimbs and hindlimbs. The forelimb, hindlimb developmental lag combined with the analysis of these datasets allow us a better insight into the dynamics of the limb growth genetic network, in particular the characterisation of genes that are differentially expressed and are putative modulators of limb growth and or candidates for limb malformation syndromes. Conclusions: The datasets and results presented in this study allow us to extend the current knowledge of the limb development and constitute an extremely relevant resource for research into the genetics of organ growth and thus ontogenesis. DGE-SAGE expression profiles for E14.5 mouse forelimb and hindlimb
Project description:We have used DGE-SAGE, a digital transcriptomics tool, to determine the expression profile of E14.5 mouse forelimbs and hindlimbs. The forelimb, hindlimb developmental lag combined with the analysis of these datasets allow us a better insight into the dynamics of the limb growth genetic network, in particular the characterisation of genes that are differentially expressed and are putative modulators of limb growth and or candidates for limb malformation syndromes. Conclusions: The datasets and results presented in this study allow us to extend the current knowledge of the limb development and constitute an extremely relevant resource for research into the genetics of organ growth and thus ontogenesis.
Project description:A control vs. genetic knockout experiment aimed at determining what RNAs are upregulated or downregulated in E13.5 mouse 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. The forelimb or hindlimb of wild-type controls or Lmx1b loss-of-function mutants was used for RNA extraction. Each array was hybridized with cDNAs of an individual limb.
Project description:Transcriptomes of mouse embryonic autopods were generated detecting expression of approximately 26179 transcripts in the developing forelimb or hindlimb autopods, representing about 58 % of the probe sets on MOE-430 A/B GeneChip. Three biological replicate array experiments were finished for each condition and MAS5.0 signal were used to do data analysis. Forty-four transcripts with expression differences higher than 2-fold were detected(T test, P<0.05), including Tbx4, Tbx5, Hoxc10 and Pitx1 which were previously shown to be differentially expressed in developing forelimb and hindlimb bud by in situ hybridization and SAGE study (Margulies 2001). RTPCR and in situ experiments confirmed several top differentially expressed genes which were newly discovered by our experiments. Vast amount of transcripts and its family members such as Bmp, Fgf, Epha, Wnt, T-box and Hox families detected to be highly expressed or differentially expressed in developing autopods, suggesting that the complexity of transcriptomes of developing autopods and dynamic differential expression and differential combinations of gene expression signals in the developing limb tissue contributes to differences in forelimb versus hindlimb patterning. The differentially expressed genes are the essential factors for morphological diversification of developing limb structures.
Project description:To investigate into the evolutionary conversation of the single-cell transcriptome of human fetal limbs, especially the principles of forelimb and hindlimb specification and proximal-distal axis establishment, we collected the forelimbs and hindlimbs of mouse embryos matching human samples. We dissected the limbs to separate proximal, middle and distal parts and generated single-cell RNA-seq data of more than 70,000 cells. Combining this dataset with our human data, we are able to see highly conserved limb cell types and limb axis drivers. Several samples from already published studies GSM4227224, GSM4227225, GSM4227226, GSM4227227 (GSE142425) and GSM4498677, GSM4498678 (GSE149368) have been reused in data analyses and the corresponding processed data are also included with this submission.
Project description:Transcriptomes of mouse embryonic autopods were generated detecting expression of approximately 26179 transcripts in the developing forelimb or hindlimb autopods, representing about 58 % of the probe sets on MOE-430 A/B GeneChip. Three biological replicate array experiments were finished for each condition and MAS5.0 signal were used to do data analysis. Forty-four transcripts with expression differences higher than 2-fold were detected(T test, P<0.05), including Tbx4, Tbx5, Hoxc10 and Pitx1 which were previously shown to be differentially expressed in developing forelimb and hindlimb bud by in situ hybridization and SAGE study (Margulies 2001). RTPCR and in situ experiments confirmed several top differentially expressed genes which were newly discovered by our experiments. Vast amount of transcripts and its family members such as Bmp, Fgf, Epha, Wnt, T-box and Hox families detected to be highly expressed or differentially expressed in developing autopods, suggesting that the complexity of transcriptomes of developing autopods and dynamic differential expression and differential combinations of gene expression signals in the developing limb tissue contributes to differences in forelimb versus hindlimb patterning. The differentially expressed genes are the essential factors for morphological diversification of developing limb structures. Keywords = microarray Keywords = mouse Keywords = autopod Keywords = limb Keywords = development Keywords = gene expression Keywords = transcriptome Keywords: repeat sample
Project description:The genetic and developmental mechanisms that control the decision between scale and feather growth â two profoundly different epidermal appendages, and an important developmental shift in the evolution of birds from their dinosaurian ancestors â remain poorly understood. Domestic pigeons display dramatic variation in foot epidermal appendages within a single species, and classical studies suggest that a small number of genes control much of this variation; thus pigeons provide a tractable model to understand skin appendage specification and variation. Here we show that feathered feet in pigeons are the consequence of a partial transformation of limb-type identity mediated by cis-regulatory changes in the hindlimb-specific transcription factor Pitx1 and forelimb-specific transcription factor Tbx5. We also demonstrate that ectopic hindlimb expression of Tbx5 is associated with the development of foot feathers in domestic chickens, suggesting that similar developmental mechanisms underlie phenotypic convergence in avian lineages that diverged over 100 MYA. These results show how qualitative and quantitative changes in expression of regional patterning genes can generate localized changes in organ fate and morphology, and provide a viable molecular mechanism for the evolution of hindlimb scale and feather distribution in dromaeosaurs. Examination of H3K27ac status in embryonic limb buds from two domestic pigeon breeds, racing homer and Indian fantail
Project description:Development of the complex structure of the vertebrate limb requires carefully orchestrated interactions between multiple regulatory pathways and proteins. Among these, precise regulation of 5’ Hox transcription factor expression is essential for proper limb bud patterning and development. Here, we identified Geminin (Gmnn) as a novel regulator of this process. A conditional model of Gmnn deficiency resulted in loss or severe reduction of forelimb skeletal elements, while both the forelimb autopod and hindlimb were unaffected. 5’ Hox gene expression expanded into more proximal and anterior regions of embryonic forelimb buds in this Gmnn-deficient model. A second conditional model of Gmnn deficiency instead caused a similar but less severe reduction of hindlimb skeletal elements and hindlimb polydactyly, while not affecting the forelimb. An ectopic posterior Shh signaling center was evident in the anterior hindlimb bud of Gmnn-deficient embryos in this model. This center ectopically expressed Hoxd13, the Hoxd13 target Shh, and the Shh target Ptch1, while these mutant hindlimb buds also had reduced levels of the cleaved, repressor form of Gli3, a Shh pathway antagonist. Together, this work delineates a new role for Gmnn in modulating Hox expression to pattern the vertebrate limb.
Project description:The analysis of differentially expressed genes is a powerful approach to elucidate the genetic mechanisms underlying the morphological and evolutionary diversity among serially homologous structures, both within the same organism (e.g., hand vs. foot) and between different species (e.g., hand vs. wing). In the developing embryo, limb-specific expression of Pitx1, Tbx4, and Tbx5 regulates the determination of limb identity. However, numerous lines of evidence, including the fact that these three genes encode transcription factors, indicate that additional genes are involved in the Pitx1-Tbx hierarchy. To examine the molecular distinctions coded for by these factors, and to identify novel genes involved in the determination of limb identity, we have used Serial Analysis of Gene Expression (SAGE) to generate comprehensive gene expression profiles from intact, developing mouse forelimbs and hindlimbs. To minimize the extraction of erroneous SAGE tags from low-quality sequence data, we used a new algorithm to extract tags from -analyzed sequence data and obtained 68,406 and 68,450 SAGE tags from forelimb and hindlimb SAGE libraries, respectively. We also developed an improved method for determining the identity of SAGE tags that increases the specificity of and provides additional information about the confidence of the tag-UniGene cluster match. The most differentially expressed gene between our SAGE libraries was Pitx1. The differential expression of Tbx4, Tbx5, and several limb-specific Hox genes was also detected; however, their abundances in the SAGE libraries were low. Because numerous other tags were differentially expressed at this low level, we performed a 'virtual' subtraction with 362,344 tags from six additional nonlimb SAGE libraries to further refine this set of candidate genes. This subtraction reduced the number of candidate genes by 74%, yet preserved the previously identified regulators of limb identity. This study presents the gene expression complexity of the developing limb and identifies candidate genes involved in the regulation of limb identity. We propose that our computational tools and the overall strategy used here are broadly applicable to other SAGE-based studies in a variety of organisms. Keywords: other
Project description:The analysis of differentially expressed genes is a powerful approach to elucidate the genetic mechanisms underlying the morphological and evolutionary diversity among serially homologous structures, both within the same organism (e.g., hand vs. foot) and between different species (e.g., hand vs. wing). In the developing embryo, limb-specific expression of Pitx1, Tbx4, and Tbx5 regulates the determination of limb identity. However, numerous lines of evidence, including the fact that these three genes encode transcription factors, indicate that additional genes are involved in the Pitx1-Tbx hierarchy. To examine the molecular distinctions coded for by these factors, and to identify novel genes involved in the determination of limb identity, we have used Serial Analysis of Gene Expression (SAGE) to generate comprehensive gene expression profiles from intact, developing mouse forelimbs and hindlimbs. To minimize the extraction of erroneous SAGE tags from low-quality sequence data, we used a new algorithm to extract tags from -analyzed sequence data and obtained 68,406 and 68,450 SAGE tags from forelimb and hindlimb SAGE libraries, respectively. We also developed an improved method for determining the identity of SAGE tags that increases the specificity of and provides additional information about the confidence of the tag-UniGene cluster match. The most differentially expressed gene between our SAGE libraries was Pitx1. The differential expression of Tbx4, Tbx5, and several limb-specific Hox genes was also detected; however, their abundances in the SAGE libraries were low. Because numerous other tags were differentially expressed at this low level, we performed a 'virtual' subtraction with 362,344 tags from six additional nonlimb SAGE libraries to further refine this set of candidate genes. This subtraction reduced the number of candidate genes by 74%, yet preserved the previously identified regulators of limb identity. This study presents the gene expression complexity of the developing limb and identifies candidate genes involved in the regulation of limb identity. We propose that our computational tools and the overall strategy used here are broadly applicable to other SAGE-based studies in a variety of organisms. Keywords: other
Project description:The bat offers an alternative paradigm to the standard mouse and chick model of limb development as it has extremely divergent forelimbs (long digits supporting a wing) and hindlimbs (short digits and claws) due the distinct requirements of both aerial and terrestrial locomotion. We used a cross-species microarray approach to identify differentially expressed (DE) genes between the bat (Minniopterus natalensis) forelimb and hindlimb autopods at Carollia developmental stages (CS) 16 and CS17, and between the bat (CS17) and mouse (E13.5) forelimb autopods. Several DE genes were identified, including two homeobox genes, Meis2, a proximal limb-patterning gene, and Hoxd11, a gene involved in digit elongation. Both genes are significantly over-expressed in the developing bat forelimb as compared to the hindlimb and equivalently staged mouse forelimbs.