Fig. 1

SON distribution in neural cells and in the developing mouse brain cortex. (a) A schematic representation of the structure of full-length human and mouse SON. The arrow indicates the portion used as an antigen for antibody production. (b) Characterization of the anti-SON antibody. E16.5 mouse brain lysates were used for Western blotting. The antibody detected multiple bands. The major band, the 260-kDa band indicated by the arrow, was almost completely absent after the antibody was absorbed with glutathione s-transferase-fusion antigen peptide (right lane). (c) The localization of SON in the nucleus of Neuro-2a cells. Cells were stained with an anti-SON (green) or anti-SRSF2 (red) antibody. The nuclei were stained with DAPI (blue). The arrowheads indicate the colocalization of SON and SRSF2. (d) Immunohistochemical distribution of SON in the developing mouse brain and its subcellular localization in mature neurons. The left panel shows a hematoxylin and eosin (HE)-stained section of the E15.5 mouse cerebral cortex. The layered structure of the developing cortex is shown on the left. MZ: marginal zone; CP: cortical plate; IZ: intermediate zone; SVZ: subventricular zone; VZ: ventricular zone. The middle panel shows the distribution of SON in an adjacent section to the HE-stained section. At E15.5, most neuronal progenitors and neurons expressed SON. The right upper panel shows a higher magnification view of the boxed area in the middle panel. SON was localized to the nucleus and was present as speckles, as in cultured cells. A similar subcellular distribution of SON was observed in mature neurons at P60 (the left lower panel)