G. Majdic et Ptk. Saunders, DIFFERENTIAL PATTERNS OF EXPRESSION OF DAX-1 AND STEROIDOGENIC FACTOR-I (SF-1) IN THE FETAL-RAT TESTIS, Endocrinology, 137(8), 1996, pp. 3586-3589
Gonadal differentiation is dependent upon a cascade of molecular and m
orphological events. Steroidogenic factor I (SF-1) and DAX-1 have been
implicated in this process. A SF-1 binding site has been reported to
be present on the DAX-1 gene. We therefore used immunocytochemistry to
determine whether these two transcription factors are co-expressed in
the fetal testis. DAX-1 was immunolocalised to the cytoplasm of inter
stitial cells from fetal testis of rat and human from day 15.5 and 16
weeks of gestation respectively. SF-l was detected in nuclei of fetal
Sertoli and interstitial cells. In the fetal rat expression of SF-1 in
interstitial cells was not uniform; cells with abundant SF-1 all cont
ained 3-beta HSD and were classified as Leydig cells. DAX-1 expression
was not exclusive to cells which contained SF-1 and SF-1/DAX-1 co-exp
ressing cells were not exclusively fetal Leydig cells. We conclude tha
t in the fetal testis expression of the DAX-1 protein is not dependent
upon the presence of SF-1 although SF-1 is present at an earlier stag
e of gestation in the gonad. DAX-1 may therefore play a separate or co
mplementary role to that of SF-I, in the modulation of testicular gene
expression and differentiation.