Soggy, a spermatocyte-specific gene, lies 3.8 kb upstream of and antipodalto TEAD-2, a transcription factor expressed at the beginning of mouse development

Investigation of the regulatory region of mTEAD-2, a gene expressed at the beginning of mouse preimplantation development, led to the surprising disco very of another gene only 3.8 kb upstream of mTEAD-2, Here we show that thi s new gene is a single copy, testis-specific gene called Soggy (mSgy) that produces a single, dominant mRNA similar to1.3 kb in length. It is transcri bed in the direction opposite to mTEAD-2, thus placing the regulatory eleme nts of these two genes in close proximity. mSgy contains three methionine c odons that could potentially act as translation start sites, but most mSGY protein synthesis in vitro was initiated from the first Met codon to produc e a full-length protein, suggesting that mSGY normally consists of 230 amin o acids (26.7 kDa), Transcription began at a cluster of nucleotides similar to 150 bp upstream of the first Met codon using a TATA-less promoter conta ined within the first 0.9 kb upstream. The activity of this promoter was re pressed by upstream sequences between -0.9 and -2.5 kb in cells that did no t express mSgy, but this repression was relieved in cells that did express mSgy, mSgy mRNA was detected in embryos only after day 15 and in adult tiss ues only in the developing spermatocytes of seminiferous tubules, suggestin g that mSgy is a spermatocyte-specific gene. Since mTEAD-2 and mSgy were no t expressed in the same cells, the mSgy/mTEAD-2 focus provides a unique par adigm for differential regulation of gene expression during mammalian devel opment.