A Unique mRNA Initiated within a Middle Intron of WHSC1/MMSET Encodes a DNA Binding Protein That Suppresses HumanIL-5 Transcription

Human interleukin (IL)-5 gene transcription is regulated by several transcription factor binding sites, including CLE 0, GATA, and a region from position − 123 to − 92 known as response element (RE)-II. By expression cloning, a partial protein was identified that bound to concatamers of RE-II. Recombinant protein derived from this initial complementary DNA (cDNA) encoding the partial protein specifically bound to RE-II–containing oligonucleotides in electromobility shift assays. The complete sequence (3,649 bp) was determined by 5 ′ rapid amplification of cDNA ends and comparisons to existing ESTs, and found to be identical to the 3 ′ half of Wolf-Hirschhorn syndrome candidate 1, (WHSC1; also known as Multiple Myeloma SET domain [MMSET]). The full-length protein contains an SET domain and two plant homeodomain–type zinc fingers. Transcription initiation of RE-II binding protein (RE-IIBP) messenger RNA (mRNA) uniquely occurred within the middle of WHSC1 near a region that exhibits complex mRNA splicing. RE...