Differentially expressed genes in zona reticularis cells of the human adrenal cortex.

The zona reticularis (ZR) cell in the human adrenal cortex is responsible for the secretion of dehydroepiandrosterone, but its biology, origin, and putative decrease in number during aging are poorly understood. In the present experiments, we investigated to what extent ZR and zona fasciculata (ZF) cells differ in patterns of gene expression. Both cell types were purified by microdissection from adult adrenal cortex specimens. After a brief period in culture, RNA was harvested from the cells and used to prepare radioactively labeled probes following amplification by PCR. Probes were used in hybridizations of arrays of cDNAs on nylon membranes (PCR products or plasmids obtained from an adrenal cDNA library). Analysis of hybridization intensities showed that 17 of the 750 genes studied differed in expression by more than 2-fold. Several genes expressed at higher levels in ZR cells encode components of the major histocompatibility complex or enzymes involved in peroxide metabolism. Members of the tubulin gene family were expressed at higher levels in ZF cells. Differential expression of four of the genes was confirmed by Northern blotting. These differences show that although ZR and ZF cells are similar in gene expression, ZR cells have a gene expression pattern related to the unique biology of this cell type.