Differential Gene Expression in the Adrenals of Normal and Anencephalic Fetuses and Studies Focused on the Fras-1-Related Extracellular Matrix Protein (FREM2) Gene

Abstract

Precis: Many genes are differentially expressed in normal compared to anencephalic human fetal adrenals (HFAs), especially the Fras-1-related extracellular matrix protein (FREM2) gene. FREM2 expression appears to be regulated by adrenocorticotrophic hormone (ACTH). Context: The expression profiles of genes responsible for cortical growth and zonation in the HFA gland are poorly characterized. The neural tube disorder anencephaly is associated with fetal adrenal hypoplasia with a large size reduction of the fetal zone of the HFA. Objective: To determine gene expression profile differences in the adrenals of anencephalic compared to normal HFAs to identify genes that may play important roles in adrenal development. Design and Methods: Fresh tissues were obtained at the time of autopsy from normal and anencephalic human fetuses delivered at mid-gestation. The following techniques were used: cell culture, messenger RNA (mRNA) extraction, microarray analysis, complementary DNA (cDNA) synthesis, quantitative real-time reverse transcriptase polymerase chain reaction (QT-PCR). Results: We identified over 40 genes expressed at levels 4-fold or greater in the normal versus anencephalic HFAs and that 28 genes were expressed at increased levels in the anencephalic HFA. The expression of FREM2 at approximately 40-fold greater levels in the normal HFA compared to the HFA of anencephalic fetuses was confirmed by QT-PCR. Expression of FREM2 in the kidney was not significantly different between normal and anencephalic fetuses. In cultured HFA cells, ACTH treatment for 48 hours increased the expression of FREM2 and a gene responsive to ACTH, CYP17, but not tyrosine hydroxylase. Conclusions: Abnormal expression of many genes may be involved in the adrenal hypoplasia seen in anencephaly. FREM2 appears to be regulated by ACTH and is the most differentially expressed gene, which may be important in the development and function of the HFA, particularly the fetal zone of the HFA.

The impact of maternal synthetic glucocorticoid administration in late pregnancy on fetal and early neonatal hypothalamic–pituitary–adrenal axes regulatory genes is dependent upon dose and gestational age at exposure

“…In contrast, P450C17 and StAR were downregulated in BET treated animals. These genes are known to be responsive to ACTH stimulation; 53,54 the present study raises the possibility that these genes may also respond to BET. One might conjecture that the upregulation of ACTH receptor and 3b HSD is offset by the downregulation of P450C17 and StAR, to explain the The impact of maternal synthetic GC administration on fetal and early neonatal HPA axes regulatory genes 85 relative similarities in plasma cortisol between BET and control animals, at least until 145 dG when fetal cortisol concentrations are lower after BET, but the information at hand does not allow that conclusion other than as speculation.…”

Establishment of a Novel Human Fetal Adrenal Culture Model that Supports de Novo and Manipulated Steroidogenesis

“…The endocrine function of HFAs and underlying mechanisms of congenital adrenal diseases are difficult to investigate as morphology and steroid hormone profile of laboratory animal modes (except higher primates) differs from HFA glands (18,19). Several approaches have previously been used to study the endocrine function of the HFA gland, predominantly as primary cell cultures of DZ and FZ cells obtained from HFA tissue cultured separately or together (20)(21)(22)(23)(24)(25)(26)(27)(28)(29). However, the lack of DZ-FZ and/or the cortical-chromaffin cell interactions in single-cell suspensions is a limitation to these models.…”