RAINBOW-TROUT SOX24, A NOVEL MEMBER OF THE SOX FAMILY, IS A TRANSCRIPTIONAL REGULATOR DURING OOGENESIS

We isolated a cDNA clone encoding a novel SRY-type HMG box (Sox) prote in, designated Sox24, from a rainbow trout ovary cDNA library. On the basis of the HMG box amino acid sequence, Sox24 can be categorized int o the same subgroup of Sox proteins as SOX4, SOX11, and SOX22. The pro teins in this group also share a highly conserved sequence at the C-te rminus. The Sox24 mRNA is expressed at high levels in the ovary, and i n-situ hybridization localized its expression to oocytes. The recombin ant protein containing the Sox24 HMG box region bound to an AACAAT seq uence strongly in a gel retardation assay. Upon co-transfection into C HO cells, the full-length Sox24 transactivated transcription from a re porter plasmid through the AACAAT binding motif. We used GAL4/Sox24 ch imeras with the DNA binding domain of yeast GAL4 at the N-terminus to map the transactivation function to the C-terminal region, which inclu ded the conserved sequence. These results suggest that Sox24 plays a r ole as a transcriptional regulator during oogenesis. (C) 1998 Elsevier Science B.V. All rights reserved.