RÉSUMÉ
During neural tube (NT) development, the notochord induces an organizer, the floorplate, which secretes Sonic Hedgehog (SHH) to pattern neural progenitors. Conversely, NT organoids (NTOs) from embryonic stem cells (ESCs) spontaneously form floorplates without the notochord, demonstrating that stem cells can self-organize without embryonic inducers. Here, we investigated floorplate self-organization in clonal mouse NTOs. Expression of the floorplate marker FOXA2 was initially spatially scattered before resolving into multiple clusters, which underwent competition and sorting, resulting in a stable "winning" floorplate. We identified that BMP signaling governed long-range cluster competition. FOXA2+ clusters expressed BMP4, suppressing FOXA2 in receiving cells while simultaneously expressing the BMP-inhibitor NOGGIN, promoting cluster persistence. Noggin mutation perturbed floorplate formation in NTOs and in the NT in vivo at mid/hindbrain regions, demonstrating how the floorplate can form autonomously without the notochord. Identifying the pathways governing organizer self-organization is critical for harnessing the developmental plasticity of stem cells in tissue engineering.
Sujet(s)
Protéine morphogénétique osseuse de type 4 , Tube neural , Chorde , Organoïdes , Animaux , Souris , Organoïdes/métabolisme , Organoïdes/cytologie , Tube neural/métabolisme , Tube neural/cytologie , Chorde/métabolisme , Chorde/cytologie , Protéine morphogénétique osseuse de type 4/métabolisme , Transduction du signal , Facteur nucléaire hépatocytaire HNF-3 bêta/métabolisme , Facteur nucléaire hépatocytaire HNF-3 bêta/génétique , Protéines Hedgehog/métabolisme , Protéines Hedgehog/génétique , Protéines de transport/métabolisme , Protéines de transport/génétique , Régulation de l'expression des gènes au cours du développement , Protéines morphogénétiques osseuses/métabolismeRÉSUMÉ
In the last decade cellular senescence, a hallmark of aging, has come into focus for pharmacologically targeting aging processes. Senolytics are one of these interventive strategies that have advanced into clinical trials, creating an unmet need for minimally invasive biomarkers of senescent cell load to identify patients at need for senotherapy. We created a landscape of miRNA and mRNA expression in five human cell types induced to senescence in-vitro and provide proof-of-principle evidence that miRNA expression can track senescence burden dynamically in-vivo using transgenic p21 high senescent cell clearance in HFD fed mice. Finally, we profiled miRNA expression in seven different tissues, total plasma, and plasma derived EVs of young and 25 months old mice. In a systematic analysis, we identified 22 candidate senomiRs with potential to serve as circulating biomarkers of senescence not only in rodents, but also in upcoming human clinical senolytic trials.