Gene profiling of human fetal and adult adrenals

The mechanisms that lead to the steroidogenic differences in the human feta l adrenal (HFA) and adult adrenal gland are not known. However, gene expres sion clearly plays a critical role in defining their distinct steroidogenic and structural phenotypes. We used DNA microarrays to compare expression l evels of several thousand transcripts between the HFA and adult adrenal gla nd. Total RNA was isolated from 18 HFA and 12 adult adrenal glands. Samples of total RNA were used to make five pools of poly A+ RNA (mRNA). Gene prof iling was done using five independent microarrays that contained between 70 75 and 9182 cDNA elements. Sixty-nine transcripts were found to have a grea ter than 2.5-fold difference in expression between HFA and adult adrenals. The largest differences were observed for transcripts that encode IGF-II (2 5-fold higher in HFA) and 3 beta -hydroxysteroid dehydrogenase (24-fold hig her in adult). Among the other genes, transcripts related to sterol biosynt hesis or to growth and development were higher in the HFA than adult adrena ls. Transcripts concerned with cellular immunity and signal transduction we re preferentially expressed in the adult adrenal. The vast majority of the 69 transcripts have not been studied with regard to adrenal function. Thus, these gene profiles provide valuable information that could help define th e mechanisms that control adrenal function.