Journal of Lipid Research, Vol 27, 1089-1096, Copyright © 1986 by Lipid Research, Inc.

ARTICLES

Expression of low density lipoprotein receptor in cultured human granulosa cells: regulation by human chorionic gonadotropin, cyclic AMP, and sterol

TG Golos, AM August and JF Strauss 3d

Steroidogenic cells utilize lipoprotein-delivered cholesterol as a primary substrate for hormone synthesis. We studied low density lipoprotein (LDL) receptors in cultured human granulosa cells to determine what factors regulate receptor expression. Granulosa cells cultured under serum-free conditions were treated with human chorionic gonadotropin (hCG) for 1.5 to 14 hr. The LDL receptor content of cells increased by approximately twofold within 6 hr of hCG treatment, and the content continued to increase for at least 14 hr, as determined by immunoblotting. The rate of LDL receptor synthesis was also demonstrated to increase within 2.5 to 3.5 hr of hCG treatment by immunoisolation of LDL receptor from cells metabolically labeled with a pulse of [35S]methionine. The cyclic AMP analogue, 8-bromo-cAMP, was also found to increase LDL receptor synthesis. This increased rate of synthesis was shown to be dependent on ongoing RNA synthesis, since actinomycin D abolished hCG- or 8-bromo-cAMP-stimulated LDL receptor synthesis. We also demonstrated that hCG- and 8-bromo-cAMP-mediated regulation of LDL receptor synthesis in granulosa cells supersedes the classical cholesterol-mediated regulation of the receptor described in fibroblasts. Although 25-hydroxycholesterol induced a decrease in LDL receptor content and synthesis within 6 hr, this action was overridden by simultaneous exposure to hCG. Our findings demonstrate the existence of a novel cAMP-mediated mechanism for regulation of LDL receptor synthesis in steroidogenic cells.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				B Lohrke, T Viergutz, and B Kruger Polar phospholipids from bovine endogenously oxidized low density lipoprotein interfere with follicular thecal function J. Mol. Endocrinol., December 1, 2005; 35(3): 531 - 545. [Abstract] [Full Text] [PDF]

				M. Fink, J. Acimovic, T. Rezen, N. Tansek, and D. Rozman Cholesterogenic Lanosterol 14{alpha}-Demethylase (CYP51) Is an Immediate Early Response Gene Endocrinology, December 1, 2005; 146(12): 5321 - 5331. [Abstract] [Full Text] [PDF]

				S. Yoshioka, H. Fujiwara, T. Higuchi, S. Yamada, M. Maeda, and S. Fujii Melanoma cell adhesion molecule (MCAM/CD146) is expressed on human luteinizing granulosa cells: enhancement of its expression by hCG, interleukin-1 and tumour necrosis factor-{alpha} Mol. Hum. Reprod., June 1, 2003; 9(6): 311 - 319. [Abstract] [Full Text] [PDF]