RA signaling induces M-opsin and inhibits L-opsin early in human retinal organoids.

(A–C) Expression of ALDH1A1, ALDH1A2, and ALDH1A3 in fetal human retinas by day of gestation and retinal region. CPM, log counts per million. Analyzed from [16]. Error bars for the 2 samples from fetal day 94 indicate SEM. Original data sets are in S3 Data. (A) Whole retina. (B) Central retina. (C) Periphery. (D) Black bars indicate temporal windows of 1.0 μm RA addition during retinal organoid culture. (E) Quantification of M and L cone ratios for RA treatments. For “No RA,” N = 3; for “RA to day 60,” N = 6; for “RA to day 130,” N = 3; and for “Late RA,” N = 5. One-way ANOVA with Dunnett’s multiple comparisons test: “No RA” L-opsin versus “RA to day 60” L-opsin, p < 0.05; “No RA” L-opsin versus “RA to day 130” L-opsin p < 0.005; “No RA” L-opsin versus “Late RA” L-opsin p = 0.9635. Error bars indicate SEM. * Indicates p < 0.05; *** indicates p < 0.005. (F–I) M-opsin (blue) and L-opsin (pink) expression in organoids grown in different RA conditions (D), quantified in (E). White dotted outlines indicate M- or L-opsin-expressing cells. White lines indicate the edge of the organoid. (F) No RA. (G) RA to day 60. (H) RA to day 130. (I) Late RA.