title: Differential regulation of glucocorticoid synthesis in murine intestinal epithelial versus adrenocortical cell lines.
abstract: Glucocorticoids are steroid hormones with important functions in development, immune regulation, and glucose metabolism. The adrenal glands are the predominant source of glucocorticoids; however, there is increasing evidence for extraadrenal glucocorticoid synthesis in thymus, brain, skin, and vascular endothelium. We recently identified intestinal epithelial cells as an important source of glucocorticoids, which regulate the activation of local intestinal immune cells. The molecular regulation of intestinal glucocorticoid synthesis is currently unexplored. In this study we investigated the transcriptional regulation of the steroidogenic enzymes P450 side-chain cleavage enzyme and 11beta-hydroxylase, and the production of corticosterone in the murine intestinal epithelial cell line mICcl2 and compared it with that in the adrenocortical cell line Y1. Surprisingly, we observed a reciprocal stimulation pattern in these two cell lines. Elevation of intracellular cAMP induced the expression of steroidogenic enzymes in Y1 cells, whereas it inhibited steroidogenesis in mICcl2 cells. In contrast, phorbol ester induced steroidogenic enzymes in intestinal epithelial cells, which was synergistically enhanced upon transfection of cells with the nuclear receptors steroidogenic factor-1 (NR5A1) and liver receptor homolog-1 (NR5A2). Finally, we observed that basal and liver receptor homolog-1/phorbol ester-induced expression of steroidogenic enzymes in mICcl2 cells was inhibited by the antagonistic nuclear receptor small heterodimer partner. We conclude that the molecular basis of glucocorticoid synthesis in intestinal epithelial cells is distinct from that in adrenal cells, most likely representing an adaptation to the local environment and different requirements.
authors.affiliation: Division of Immunopathology, Institute of Pathology, University of Bern, Murtenstrasse 31, 3010 Bern, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Mueller
authors.forename: Atanas
authors.initials: A
authors.lastname: Atanasov
authors.forename: Igor
authors.initials: I
authors.lastname: Cima
authors.forename: Nadia
authors.initials: N
authors.lastname: Corazza
authors.forename: Kristina
authors.initials: K
authors.lastname: Schoonjans
authors.forename: Thomas
authors.initials: T
authors.lastname: Brunner
mesh_terms: D000302:Adrenal Cortex / Q000166:cytology* / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000235:genetics / Q000378:metabolism; D000242:Cyclic AMP / Q000096:biosynthesis / Q000494:pharmacology; D005786:Gene Expression Regulation; D005938:Glucocorticoids / Q000096:biosynthesis*; D018398:Homeodomain Proteins / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D020218:Response Elements; D013252:Steroid 11-beta-Hydroxylase / Q000235:genetics / Q000378:metabolism; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection
chemical_list: D005938:Glucocorticoids; D018398:Homeodomain Proteins; C431936:Nr5a2 protein, mouse; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; C515058:steroidogenic factor 1, mouse; D000242:Cyclic AMP; D013252:Steroid 11-beta-Hydroxylase; D002786:Cholesterol Side-Chain Cleavage Enzyme