Figure 3. Fezf1 Promotes the Polarization and Migration of ON Starburst Amacrine Cells by Repressing Rnd3 Expression. See alsoFigure S3.

(A) GFP-labeled ON SACs (left, middle) and sketches of representative morphologies (right) at indicated embryonic ages in Fezf1 ^GFP/+ and Fezf1^GFP/GFP retinas. Embryonic SACs are identified by co-expression of Sox2 (magenta) and Isl1 (blue).

(B) Polar plot of the angle (radial axes) and length (X/Y axes) of the prominent neurite of individual ON SACs in E16.5 Fezf1 ^GFP/+ and Fezf1^GFP/GFP retinas.

(C) Percent of total SACs expressing strong or weak levels of Rnd3 transcript (defined in STAR Methods) at indicated embryonic ages (left; ON and OFF SACs are quantified separately at E16.5 based on the differential positioning of their somas across the IPL) (see Figure S3B for representative images) and in P0 Fezf1^GFP/+ and Fezf1^GFP/GFP retinas (right).

(D) Rnd3, Chat, and GFP expression in SACs from P0 Fezf1 ^GFP/+ and Fezf1^GFP/GFP retinas detected by RNAscope FISH. Circles outline SACs, and mutant ‘ON’ SACs are GFP- and Chat-positive (asterisked).

(E) P14 retina sections transduced with AAVs expressing control (shScramble, top), or shRnd3 (bottom) hairpins introduced at E13.5. DsRed marks AAV-transduced cells.

(F) Ratios of transduced SACs in the INL compared to the GCL for the indicated conditions. Bars show mean ± SEM from 4–10 images from 3 animals per condition.

Scale bars are 20μm. ***, p<0.001 by Student’s t-test.