ANALYSIS OF THE MOUSE SELENOPROTEIN P-GENE

vertebrates several proteins containing a covalently bound selenocyste ine residue have been identified. Among these, selenoprotein P is the most unusual one: depending on the species, 8-12 selenocysteine residu es are cotranslationally integrated into the polypeptide chain. The pr otein was traced in rat plasma, but its role has not been worked out s o far. In order to improve our understanding on selenoprotein P we inv estigated its tissue-specific expression and its genomic DNA. RNA in s itu hybridization analyses confirmed the liver-specific expression in mice. Selenoprotein P was also found to be expressed in testis, brain, gut, and hemato cells. The murine selp gene contains five exons withi n 10.3 kb with a coding sequence restricted td exons 2 to 5. The compl ete gene including the selp promoter was sequenced. One TATA motif 38 bp upstream to exon 1 suggests transcription of selp by RNA, polymeras e II. Within the 1116 bp upstream of exon 1 four hepatic nuclear facto r 3 beta (HNF3 beta) binding motifs were found, which is in line with liver-specific expression of selenoprotein P.The expression in hematop oietic cells might be due to multiple GATA-1 motifs. Two BRN-2 motifs suitable for the binding of brain-specific regulatory factors correlat ed to the selenoprotein P:expression in the cerebellum. selenoprotein P was also expressed in Leydig cells which could be regulated by bindi ng proteins docking to the SRY motifs present in the promoter region.