Project description:Osteoblasts are the only somatic cell type with bone-forming ability. While the cellular and molecular mechanisms underlying their differentiation and function have been identified, their dynamic control in vivo is unclear. By intravital multiphoton microscopy of live bone tissues of osteoblast fluorescent reporter mice, we visualized intact mature osteoblasts in vivo and found that they actively secrete and capture extracellular microvesicles. Microvesicles from mature osteoblasts contain the microRNA miR-143-3p, which inhibits osteoblast differentiation. Osteoblast-specific deletion of miR-143 increased bone formation and miR-143-deficient microvesicles induced recovery from bone defect. In sum, we report a novel mode of intercellular communication in vivo via microRNA-containing extracellular vesicles, which controls bone homeostasis.
Project description:In the social amoebae (Dictyostelia) quorum sensing system mediates aggregation of single cells into multicellular aggregates by chemotactic movement towards gradients of diffusible molecules known as acrasins. The acrasin of P. violaceum is the unusual dipeptide N-propionyl-gamma-L-glutamyl-L-ornithine-delta-lactam-ethylester, known as glorin. Phylogenetic analysis has indicated that P. violaceum is more related to the most derived group 4 dictyostelids than to the ancient group 2 polysphondylids such as P. pallidum. Nevertheless it has been reported that P. pallidum cells respond to glorin in chemotaxis assays. This has led to the assumption that glorin-based communication may be the most ancient form of intercellular communication that Dictyostelia invented to organize early steps of multicellular development. In this study we show that glorin mediates rapid changes in gene expression at the transition from vegetative growth to aggregation, apparently without pronounced cross-talk with the cyclic AMP-based communication system that coordinates post-aggregation events in this species. We describe glorin-mediated changes in gene expression in the social amoeba Polysphondylium pallidum at the transition from unicellular growth to multicellular development. Comparison of gene expression in growing cells versus cells starving for 2 or 3 hours in the presence or absence of glorin.
Project description:The human genome encodes ~1,900 secreted proteins, many of which mediate intercellular communication. Secreted proteins do not act cell-autonomously, limiting systematic approaches to characterize their functions. Here we introduce SecAct (Secreted Activity, https://secact.ccr.cancer.gov ), a computational framework that infers the signaling activities of 1,170 human secreted proteins from spatial, single-cell and bulk transcriptomic data. The inference model harnesses precomputed intercellular signaling signatures trained on 1,258 spatial transcriptomics samples spanning 37 cancer types. Transcriptomics data from antisecreted protein therapies validate SecAct's accuracy in predicting the repression of secreted protein activity following treatment. For spatial and single-cell transcriptomics data, SecAct provides interactive modules for analyzing secreted protein-mediated cell-cell communication. Applying SecAct to 54 cancer immunotherapy cohorts comprising 5,174 patients, we identified secreted proteins associated with tumor immunity. In vivo experiments validated lymphocyte antigen 86 (LY86), whose function in cancer was previously unknown, as an antitumor regulator.
Project description:The transparency of lens relies on proper intercellular communication. Exosomes are crucial mediators of intercellular communication and play a key role in organ homeostasis and development. However, their presence and dynamics in the lens remain unclear. This study aimed to investigate the existence of endogenous exosomes in the lens and explore their potential functions. Using the cryaa promoter to drive Cd63-AcGFP expression, we achieved lens-specific exosome labeling in zebrafish. Live imaging revealed the presence of exosomes in lens cells during development and their movement trajectory under physiological conditions. Additionally, lens-derived exosomes (lens-Exos) facilitate communication not only between lens cells but also with surrounding tissues. We also identified that the biogenesis of Cd63+ exosomes in the lens is regulated by the Syntenin-a pathway. As knockdown of Syntenin-a in zebrafish resulted in delayed lens development, indicating a potential role for exosomes in normal lens development. Furthermore, in vitro hESC-lentoid induction showed that extracellular vesicles from ROR1+ lens progenitor cells (ROR1+ LPCs-EVs) promote lentoid differentiation. Proteomic analysis provided insights into the functions of ROR1+ LPCs-EVs. Overall, our study is the first to observe endogenous exosomes in the lens, providing new insights into lens pathophysiology and a potential strategy for modulating the lens microenvironment.