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ACTH regulates LDL receptor and CLA-1 mRNA in the rat adrenal cortex
1Haartman Institute, Department of Pathology, University of Helsinki, Finland.
Abstract:
Rat adrenocortical cells utilize both low density lipoprotein (LDL) and high density lipoprotein (HDL) cholesterol for steroid hormone production. In addition to exogenous lipoprotein-derived cholesterol, cells produce cholesterol de novo. Adrenocorticotropin (ACTH) increases both steroid hormone secretion and uptake of LDL and HDL. We studied the expression of LDL receptor mRNA and CLA-1 (a putative HDL receptor) mRNA in cultured rat adrenocortical cells. ACTH increased the amounts of LDL receptor mRNA during 2 to 48 h of stimulation, the highest levels being detected after 2-4 h. Similar results were obtained with cyclic AMP (cAMP) derivatives, 8-bromo cAMP (8-Br cAMP) or dibutyryl cAMP. ACTH increased CLA-1 mRNA during 2 to 24 h of stimulation, the highest levels being detected after 4 h. In conclusion, ACTH up regulates both LDL and HDL receptor mRNA in rat adrenocortical cells.