The cortical subventricular zone-specific molecule Svet1 is part of the nuclear RNA coded by the putative Netrin receptor gene Unc5d and is expressed in multipolar migrating cells

Although Svet1 RNA is a widely used marker for the subventricular zone (SVZ) of the embryonic cerebral cortex, its function remains completely unknown. We report finding that Svet1 contains a high proportion of repetitive sequences and maps in the first intron of the putative Netrin receptor gene Unc5d. The direction of transcription of Svet1 is the same as that of Unc5d. The Svet1 RNA was detected in the nucleus but not in the cytoplasm. Both Svet1/Unc5d RNAs and UNC5D protein were localized in the multipolar cells in the SVZ throughout cortical development. These results suggest that Svet1 RNA is part of the sequence of the primary transcript of Unc5d in the nucleus that is spliced out before the mRNA is transported to the cytoplasm. Thus, the previously reported "SVZ-specific expression of the Svet1 RNA" in fact indicates putative involvement of UNC5D signaling in the multipolar migrating cells.