Extended Data Figure 4 : SecGFP and Fgf3–GFP localization in apically polarized secretory path.

From: Luminal signalling links cell communication to tissue architecture during organogenesis

Extended Data Figure 4

a, Golgi, labelled by GM130-tdTomato (white) mRNA injection, are localized apically around rosette centres in lateral line primordium (cldnb:lynGFP, red). Scale bar, 20 µm. b, Maximum projection of apical optical sections of a transgenic lexOP:fgf3–GFP primordium, counterstained for ZO1, shows intracellular Fgf3–GFP signal around rosette centres in addition to luminal signal. Scale bar, 50 µm. c, Single cell expressing Fgf3–GFP feeds the central microlumen through apical secretion (expressing cell indicated with yellow dashed line). Scale bar, 5 µm. d, Mosaic primordium showing apically localized intracellular Fgf3–GFP signal co-localizes with Golgi marker GM130-tdTomato. Scale bar, 5 µm. e, Intracellular Fgf3–GFP and secGFP localization at secretory path. f, Golgi (GM130-tdTomato) co-labelling with secGFP. Scale bar, 5 µm. g, Endoplasmic reticulum (mKate2-KDEL) co-labelling with secGFP. Scale bar, 5 µm. h, Signal distribution of secGFP and Fgf3–GFP in three dimensions within the expressing cell where Golgi was taken as a central point. Comparison of Fgf3–GFP and secGFP density profiles suggests that Fgf3–GFP is more pronounced in Golgi (nsecGFP = 5, nFgf3–GFP = 4). i, Imaging of Fgf3–GFP-expressing clones (white dashed lines) with high sensitivity reveals Golgi localization (yellow arrowheads) of Fgf3–GFP in expressing cells close to the microlumen (asterisk) and intracellular vesicles in connected non-expressing cells (white arrowheads). No extracellular signal besides microluminal accumulation was detected. Scale bar, 5 µm.