Knockdown of Slit signalling during limb development leads to a reduction in humerus length

Acknowledgements: This project was funded by an EastBio BBSRC DTP PhD Studentship to AR. The authors thank past and present lab staff for helpful discussions.Peer reviewedPostprin

Genetic association and characterization of FSTL5 in isolated clubfoot

ACKNOWLEDGEMENTS: The Atherosclerosis Risk in Communities Study is carried out as a collaborative study supported by National Heart, Lung, and Blood Institute contracts (HHSN268201100005C, HHSN268201100006C, HHSN268201100007C, HHSN268201100008C, HHSN268201100009C, HHSN268201100010C, HHSN268201100011C, and HHSN268201100012C). The authors thank the staff and participants of the ARIC study for their important contributions. Funding for GENEVA was provided by National Human Genome Research Institute grant U01HG004402 (E.Boerwinkle). We thank H. Hobbs and J. Cohen for contributing control samples for replication genotyping, Nadav Ahituv for sharing RNA-seq data for both bat and mouse embryonic limb buds, Tommy Hyatt for designing the custom genotyping assay, and members of the UT Southwestern Transgenic Core facility, including John Ritter, Mylinh Nguyen, and Robert Hammer. Publicly available mouse embryonic expression analysis results were provided online at https://oncoscape.v3.sttrcancer.org/atlas.gs.washington.edu.mouse.rna/landing (24). The authors acknowledge the contributions and support of the Center for Excellence in Clubfoot Research at Scottish Rite for Children, including Shawne Faulks and Kristhen Atala. Fstl5 mutant rats were produced by the NIH Mutant Rat Resource at UT Southwestern Medical Center (R24RR03232601, R24OD011108, R01HD036022, and (5R01HD053889). This study was supported by funding from the Scottish Rite for Children Research Fund (J.J.R.), Shriners Hospital for Children (J.T.H), and the National Institutes of Health award R01HD043342 (J.T.H.).Peer reviewedPostprin

Targeting the IL-6-Yap-Snail signalling axis in synovial fibroblasts ameliorates inflammatory arthritis

ACKNOWLEDGEMENTS The authors thank staff at the University of Aberdeen’s Animal Facility, Microscopy and Histology Facility, qPCR Facility, and the Iain Fraser Cytometry Centre for their expert support. The authors also thank the NHS Grampian Biorepository for facilitating the collection of human tissue samples. Additionally, thanks is given to Denis Evseenko for critical review of the manuscript. Funding This work was supported by funding from the Medical Research Council (grants MR/L020211/1, MR/L022893/1), Versus Arthritis (formerly Arthritis Research UK, grants 20775, 19429, 21156, 20050, 19667, 20865, 21800), Tenovus Scotland (grant G13/14), and European Union’s Horizon 2020 research and innovation programme under Marie Sklodowska Curie (Grant 642414).Peer reviewedPublisher PD

Identification of the skeletal progenitor cells forming osteophytes in osteoarthritis.

OBJECTIVES: Osteophytes are highly prevalent in osteoarthritis (OA) and are associated with pain and functional disability. These pathological outgrowths of cartilage and bone typically form at the junction of articular cartilage, periosteum and synovium. The aim of this study was to identify the cells forming osteophytes in OA. METHODS: Fluorescent genetic cell-labelling and tracing mouse models were induced with tamoxifen to switch on reporter expression, as appropriate, followed by surgery to induce destabilisation of the medial meniscus. Contributions of fluorescently labelled cells to osteophytes after 2 or 8 weeks, and their molecular identity, were analysed by histology, immunofluorescence staining and RNA in situ hybridisation. Pdgfrα-H2BGFP mice and Pdgfrα-CreER mice crossed with multicolour Confetti reporter mice were used for identification and clonal tracing of mesenchymal progenitors. Mice carrying Col2-CreER, Nes-CreER, LepR-Cre, Grem1-CreER, Gdf5-Cre, Sox9-CreER or Prg4-CreER were crossed with tdTomato reporter mice to lineage-trace chondrocytes and stem/progenitor cell subpopulations. RESULTS: Articular chondrocytes, or skeletal stem cells identified by Nes, LepR or Grem1 expression, did not give rise to osteophytes. Instead, osteophytes derived from Pdgfrα-expressing stem/progenitor cells in periosteum and synovium that are descendants from the Gdf5-expressing embryonic joint interzone. Further, we show that Sox9-expressing progenitors in periosteum supplied hybrid skeletal cells to the early osteophyte, while Prg4-expressing progenitors from synovial lining contributed to cartilage capping the osteophyte, but not to bone. CONCLUSION: Our findings reveal distinct periosteal and synovial skeletal progenitors that cooperate to form osteophytes in OA. These cell populations could be targeted in disease modification for treatment of OA