[Alternative promoters localised in SGMS1 gene introns take part in regulation of its expression in human tissues].

Sphingomyelin synthase 1 (SMS1) is an enzyme of vital importance which is responsible for the synthesis of sphingomyelin and diacylglycerol from phosphatidylcholine and ceramide in eukaryotic cells. Previously we have investigated in detail the structure of SGMS1 human gene and identified a lot of its transcripts. We revealed the isoforms of mRNA differing in the 5'-UTR and coding the full-length protein, and also the transcripts arising from alternative combination of the exons localized in the coding region of the gene and 3'-UTR. From the results of computer analysis it follows that the synthesis of transcripts differing in the 5'-UTR is enabled by the different promoters of SGMS1 gene. It has been found in the present work by the method of real-time PCR that the content of five alternative transcripts of this gene, differing in the 5'-UTR, is substantially dissimilar among human tissues. In all the investigated tissues those transcripts are presented most prominently whose synthesis takes place under the control of the distal promoter including exon 1. In lesser extent are presented the transcripts including 5'-end exons whose synthesis is enabled by the promoters localized in introns of this gene. The differential level of content of SGMS1 gene transcripts, differing in the 5'-UTR, indicates that the use of the alternative promoters is tissue-specific and apparently strictly regulated. The structural organization of 5'-UTR variants of SGMS1 transcripts, directed by alternative promoters, is substantially different; this can provide regulation of the gene functioning on post-transcriptional level.