S. Dolci et al., IDENTIFICATION OF A PROMOTER REGION GENERATING SRY CIRCULAR TRANSCRIPTS BOTH IN GERM-CELLS FROM MALE-ADULT MICE AND IN MALE-MOUSE EMBRYONALGONADS, Biology of reproduction, 57(5), 1997, pp. 1128-1135
The mouse testis determining gene Sry is expressed in somatic cells of
the differentiating male gonad as a linear transcript, encoding a tra
nscription factor containing an HMG box. In the adult mouse testis, Sr
y expression occurs in meiotic and postmeiotic germ cells. The mouse g
enomic Sry locus is characterized by two arms of a large inverted repe
at, flanking a unique region that, between an acceptor and a donor spl
ice site, contains a single exon encoding the Sry protein. In germ cel
ls from the adult mouse testis, Sry RNA is a circular molecule, which
is generated by an inverted splicing event that utilizes the above-men
tioned splice sites. Thus, a circular exon is spliced out starting fro
m a large linear RNA precursor containing both arms of the inverted re
peat, which pair and generate a large stem-loop structure. Using rever
se transcription-polymerase chain reaction and an RNase protection ass
ay, we have now mapped the 5' end of this precursor RNA in the 5' arm
of the inverted repeat. Gel mobility shift assay and in vitro transcri
ption with nuclear extracts from adult germ cells further confirm that
a region immediately 5' upstream of two transcriptional initiation si
tes of the precursor RNA contains a promoter sequence in which two con
sensus Sry binding sequences are specifically recognized by nuclear fa
ctors present in adult germ cells but not in Sertoli cells. We also sh
ow that the linear precursor of the Sry circular transcript and its sp
licing product are specifically expressed not only in adult germ cells
but also in male embryonal gonads between 11.5 and 13.5 days postcoit
um, immediately after the expression of the linear transcript starting
from the unique region.