Fig. 2.

OSM induces reversible cell cycle exit and a molecular signature of quiescence. a FACS-sorted muscle stem cells purified from luciferase transgenic mice were cultured for 7 days at 2500 sorted counts per well (~31 cells/mm²) in the presence (closed circle) or absence (open circles) of OSM, as well as low dose FGF (0.5 ng/ml). Serial in vitro BLI was performed at the indicated timepoints. Mean±SD is shown, n = 4 replicates. b FACS-sorted MuSC cultured for 6 days as in (A) were pulsed with EdU for the last 12 h of culture. Mean±SD is shown, n = 4 replicates. c Induction of cell cycle exit in myoblasts in response to OSM. Primary myoblasts were cultured for 3 days in growth medium with (red) out without (gray) added OSM. Cells were fixed, intracellular staining performed for mitotic H3S10 phosphorylation, and analyzed by flow cytometry. d Diagram demonstrating overlap between a bioinformatically-derived gene expression “quiescence signature” for satellite cells, and genes regulated during OSM-treatment of muscle stem cells in vitro. OSM regulation data was derived mean of 2 biological replicates. e Schematic of switch experiment to demonstrate reversibility of OSM-induced cell cycle exit (left). FACS-sorted MuSC were cultured for 6 days under the indicated conditions, and then pulsed with EdU for the final 12 h of culture (right). Mean±SD is shown, n = 4 replicates; greater than 300 cells were counted per replicate