The scaRNA2 is produced by an independent transcription unit and its processing is directed by the encoding region

The C/D box scaRNA2 is predicted to guide specific 2′-O-methylation of U2 snRNA. In contrast to other SCARNA genes, SCARNA2 appears to be independently transcribed. By transient expression of SCARNA2-reporter gene constructs, we have demonstrated that this gene is transcribed by RNA polymerase II and that the promoter elements responsible for its transcription are contained within a 161 bp region upstream of the transcription start site. In mammals, we have identified four cross species conserved promoter elements, a TATA motif, an hStaf/ZNF143 binding site and two novel elements that are required for full promoter activity. Binding of the human hStaf/ZNF143 transcription factor to its target sequence is required for promoter activity, suggesting that hStaf/ZNF143 is a fundamental regulator of the SCARNA2 gene. We also showed that RNA polymerase II continues transcription past the 3′-end of the mature RNA, irrespective of the identity of the Pol II promoter. The 3′-end processing and accumulation are governed by the sole information contained in the scaRNA2 encoding region, the maturation occurring via a particular pathway incompatible with that of mRNA or snRNA production.