12515 Single-Nuclei Multiome Analysis Of The Adrenal Gland Identifies Putative Novel Regulators Of Zone-Specific Steroidogenesis

Abstract Disclosure: A.M. Lerario: None. J. Rege: None. A. Blinder: None. G.D. Hammer: None. W.E. Rainey: None. The human adrenal cortex comprises three distinct histological zones: the outer zona glomerulosa (ZG), responsible for aldosterone production, the middle zona fasciculata (ZF), producing cortisol, and the inner zona reticularis (ZR), contributing to the synthesis of DHEAS. One key mechanism of zone-specific steroidogenesis lies in the selective expression of membrane receptors for the endocrine regulators AngII and ACTH in the ZG and ZF/ZR, respectively. Activation of these receptors drives zone-specific expression of CYP11B2, CYP11B1, and SULT2A1, the steroidogenic enzymes responsible for the final step of aldosterone, cortisol, and DHEAS biosynthesis, respectively. While the downstream intracellular signaling pathways governing the expression of these enzymes are well characterized, the transcriptional regulatory mechanisms remain incompletely understood. To identify potential transcriptional regulators and chromatin regions controlling the zone-specific expression of steroidogenic enzymes, we conducted a single-nuclei multiome study (RNAseq and ATACseq) in three adrenal glands from adult kidney donors with normal zonation confirmed by immunohistochemistry. As expected, our analysis revealed distinct cell populations with gene expression profiles characteristic of each histological zone, displaying zone-specific expression patterns of CYP11B2, CYP11B1, and SULT2A1. Furthermore, within each zone, subpopulations of cells exhibited variable expression of steroidogenic enzymes, indicative of diverse states of differentiation or cellular activation. Moreover, we identified zone-specific changes in chromatin accessibility spanning the promoters and putative distal regulatory regions of CYP11B2, CYP11B1, and SULT2A1. Transcription factor binding motif analysis of these regions identified known and potentially novel transcriptional regulators controlling the expression of these genes. Our analyses underscore the complexity of the regulatory network that controls the transcription of zone-specific steroidogenic enzymes, highlighting the interplay between promoter-bound transcriptional regulators and distal cis-regulatory elements. Presentation: 6/2/2024