Fig. 2: The cell size-dependent G1/S transition is invariant across the mammalian intestinal epithelial lineage.
From: The G1/S transition in mammalian stem cells in vivo is autonomously regulated by cell size
A Schematic of mouse intestinal organoid development. During the spheroid stage, all cells actively cycle. As the organoid matures, crypt domains are established and maintained, and active cycling is restricted to Lgr5+ stem cells and Lgr5- TA cells. B A z-slice of a spheroid stage intestinal organoid expressing H2B-miRFP670, Cdt1-mCherry (FUCCI-G1), and Geminin-mVenus (FUCCI-S/G2/M) is shown. C A z-slice of a mature intestinal organoid crypt expressing Lgr5-GFP and Cdt1-mKO2 (FUCCI-G1) is shown. The autofluorescent lumen is outlined in yellow. D An example of a single spheroid stage cell tracked from birth to the G1/S transition. Solid yellow outlines are the 3D nuclear segmentation. Dotted yellow outlines are the mother cell’s position. E An example of a single Lgr5+ intestinal stem cell tracked from birth to the G1/S transition. Solid yellow outlines are the 3D nuclear segmentation. Dotted yellow outlines are the mother cell’s position and the cell’s position post G1/S transition. Black asterisk denotes a non-cycling Paneth cell. F The nuclear volume at birth of cycling organoid cells is inversely correlated with G1 duration for all cell types. Pearson’s R = −0.22 (p = 0.16) for spheroid stage cells, R = −0.42 (p = 2e–3) for stem cells, and −0.30 (p = 1e–5) for TA cells. Blue: spheroid; green: stem; magenta: TA. G The nuclear volume at birth of cycling organoid cells is inversely correlated with the amount of nuclear growth during G1 phase. Slope = −0.47 (p = 0.001) for spheroid stage cells, −0.75 (p = 0.002) for stem cells, and −0.85 (p = 1.2e-5) for TA cells. Nuclear size at birth (H) and at G1 exit (I) is quantified for spheroid stage cells, mature stem cells, and mature TA cells. Median is shown in white. Quartiles are shown as the gray box. The non-outlier data range is shown as whiskers. Linear regression is solid line. 95% confidence intervals is shaded area. P values are two-sided T test. Source data are provided as a Source Data file.
