Project description:Mouse embryonic stem cells were used to generate cell types of limb development and characterized using single-cell mRNA-sequencing.
Project description:By using single cell RNA-seq,We dissect the cellular heterogeneity and transcriptome profiles during limb development, and reveal the characteristic features of limb development and musculoskeletal stem/progenitor cell populations involved in limb lineage development. Our study therefore systematically decoded molecular markers and cellular program of limb development that would shed lights on limb developmental biology.
Project description:Human limbs emerge during the fourth post-conception week as mesenchymal buds, which develop into fully formed limbs over the subsequent months. This process is orchestrated by numerous temporally and spatially restricted gene expression programmes, making congenital alterations in phenotype common. Decades of work with model organisms have defined the fundamental mechanisms underlying vertebrate limb development, but an in-depth characterization of this process in humans has yet to be performed. Here we detail human embryonic limb development across space and time using single-cell and spatial transcriptomics. We demonstrate extensive diversification of cells from a few multipotent progenitors to myriad differentiated cell states, including several novel cell populations. We uncover two waves of human muscle development, each characterized by different cell states regulated by separate gene expression programmes, and identify musculin (MSC) as a key transcriptional repressor maintaining muscle stem cell identity. Through assembly of multiple anatomically continuous spatial transcriptomic samples using VisiumStitcher, we map cells across a sagittal section of a whole fetal hindlimb. We reveal a clear anatomical segregation between genes linked to brachydactyly and polysyndactyly, and uncover transcriptionally and spatially distinct populations of the mesenchyme in the autopod. Finally, we perform single-cell RNA sequencing on mouse embryonic limbs to facilitate cross-species developmental comparison, finding substantial homology between the two species.
Project description:The salamander limb regenerates only the missing portion. Each limb segment can only form segments equivalent to- or more distal to their own identity, relying on a property termed “positional information”. How positional information is encoded in limb cells has been unknown. By cell-type-specific chromatin profiling of upper arm, lower arm, and hand, we found segment-specific levels of histone H3K27me3 at limb homeoprotein gene loci but not their upstream regulators, constituting an intrinsic segment information code. During regeneration, regeneration-specific regulatory elements became active prior to the re-appearance of developmental regulatory elements. This means that, in the hand segment, the permissive chromatin state of the hand homeoprotein gene HoxA13 engages with regeneration regulatory elements, bypassing the upper limb program. Profiling chromatin accessibility (ACRs) of Axoltol limb connective tissue cells, and compare among developmental limb buds, and mature limb at different segments and regeneration time points.
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. DGE-SAGE expression profiles for E14.5 mouse forelimb and hindlimb
Project description:26 limb-girdle muscular dystrophy patients from Latvia and 34 patients from Lithuania with clinical symptoms of limb-girdle muscular dystrophies, along with 204 healthy unrelated controls were genotyped for 96 most frequent known limb-girdle muscular dystrophies causing mutations for the region, using VeraCode GoldenGate system. More information can be found in article Robust genotyping tool for autosomal recessive type of limb-girdle muscular dystrophies in BMC Musculoskeletal Disorders by I. Inashkina et al.
Project description:Limb development is a powerful model to investigate transcriptional complexity during differentiation and development, as tissue types appear at various stages, with unique transcriptional signatures. So far, most studies have used conventional expression arrays, which can identify only a predetermined set of cDNAs. However there is growing evidence that most of the non-coding part of the genome is transcribed as well. We took advantage of genomic tiling arrays, which cover most of the mouse genome, to look at limb transcriptomes in an unbiased manner, by identifying all genic- and intergenic transcripts. We selected three developmental stages (E11.5 ; E13.5 ; E15.5), covering a large period of limb organogenesis, during which the limb evolves from a mostly homogenous mesenchymal cell population to more specialized tissue types such as cartilage, bone, muscle and skin.
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: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:Mutant MetRS in MSCs allows efficient and specific identification of dynamic cell proteomics in situ, which reflect the functions and adaptive changes of MSCs that may be leveraged to understand and improve stem cell therapy in critical limb ischemia