Expression of Cyp21a1 and Cyp11b1 in the fetal mouse testis

Abstract

Fetal Leydig cells and fetal adrenocortical cells may share a common progenitor cell. Both cell types show several similarities, particularly in relation to their primary steroidogenic function. Differences in steroid secretion are largely due to the expression of 21-hydroxylase (CYP21A1) and 11b-hydroxylase (CYP11B1) activity in the adrenal. To determine whether expression of these enzymes defines a clear difference between adrenocortical and Leydig cells, or is further evidence of a link between the cell types, we have measured Cyp21a1 and Cyp11b1 expression and related enzyme activity in the fetal testis. Expression of both Cyp21a1 and Cyp11b1 was clearly detectable in the fetal testis by RT-PCR and Southern blotting. Real-time PCR studies showed that Cyp11b1 was expressed only in the fetal/neonatal testis with no expression in the pubertal or post-pubertal animal. Cyp21a1 was also predominantly expressed in the fetal testis although some lower expression was also seen in the adult. Expression of Cyp21a1 and Cyp11b1 in neonatal testicular cells was unaffected by incubation in vitro with human chorionic gonadotrophin or ACTH. Using immunohistochemistry, CYP21A1 was localised to a subset of interstitial steroidogenic cells in the fetal testis although CYP11B1 was not detectable. Incubation studies showed that 21-hydroxylase activity was present in the tissue although 11b-hydroxylase activity could not be detected. Results indicate that a subpopulation of steroidogenic cells in the fetal testis express Cyp21a1 and show 21-hydroxylase activity. This may provide further evidence of a link between fetal Leydig cells and adrenocortical cells but does not discount the possibility that these steroidogenic cells represent 'ectopic' adrenal cells. Reproduction (2007) 134 585-591

Gene dosage effects and transcriptional regulation of early mammalian adrenal cortex development

“…Even though the specificity of expression is relatively strict in adult tissues, numerous reports have shown that some gonadspecific enzymes are expressed in the adrenal during development. Conversely, adrenal enzymes were observed in the developing gonad [9][10][11][12][13][14]. This suggests that, in agreement with histological studies, the adrenal cortex and gonads have a common embryological origin.…”

Combined Loss of the GATA4 and GATA6 Transcription Factors in Male Mice Disrupts Testicular Development and Confers Adrenal-Like Function in the Testes

“…These clusters are likely derived from the expansion of the rare adrenal-like cells present in the developing testis (49,50). In the normal testis, the significance of the presence of these cells is currently unknown.…”

Prevalence of Testicular Adrenal Rest Tissue in Neonates

“…Our group described the presence of ACTH receptors in TART of 8 adult CAH patients [16]. Additionally, Hu et al [17] demonstrated the presence of a subset of interstitial steroidogenic cells within the fetal mice testis which express Cyp21a1. RT-PCR experiments showed that testicular Cyp21a1 mRNA expression levels fall post-partum within 10 days.…”