Project description:Steroidogenic acute regulatory protein (Star) facilitates cholesterol transfer into the inner mitochondrial membrane in the acute and regulated production of steroid hormones. Mice lacking Star (Star-/-) share the phenotypes with patients with congenital lipoid adrenal hyperplasia such as compromised production of steroid hormones and florid accumulation of cholesterol esters in adrenal glands and gonads. To define specific patterns of molecular changes with disruption of Star, we performed a transcriptome analysis of steroidogenic cells in adrenal glands. We harvested adrenal glands at E17.5 or 18.5 from seven wild-type (Star+/+) mice or four Star-/- mice having the transgene targeting enhanced green fluorescent protein (eGFP) under the control of regulatory sequences of mouse Star gene. Steroidogenic cells were selectively isolated by fluorescent-activated cell sorting. The gene expression profile of the fluorescence-positive cells was obtained with Agilent Whole Mouse Genome Microarray and was confirmed by quantitative real-time PCR. We identified 961 and 622 genes that were significantly up-regulated and down-regulated, respectively, in Star-/- mice compared with Star+/+ mice (fold difference ≥2, p value of Student t test <0.05, and Benjamini-Hochberg false discovery rate of multiple comparison test <0.2). In Star-/- mice, expression levels of genes involved in cholesterol mobilization and efflux or immune response as antigen presenting cells were significantly increased, and transition from fetal to adult adrenocortical cells were significantly decreased, whereas those of genes related to steroid hormone biosynthesis or cholesterol biosynthesis and influx were not significantly changed. The trancriptome analysis revealed hitherto undescribed characteristic changes in adrenocortical cells and expanded our understanding of the pathophysiology of the steroidogenic cells with disruption of Star. Gene expression profiles of isolated adrenal steroidogenic cells were compared between seven wild-type mice and four knockout mice lacking steroidogenic acute regulatory protein at E17.5-18.5.

Project description:Steroid hormones regulate essential physiological processes and inadequate levels are associated with various pathological conditions. In testosterone-producing Leydig cells, steroidogenesis is strongly stimulated by LH via its receptor leading to increased cAMP production and expression of the steroidogenic acute regulatory (STAR) protein, which is essential for the initiation of steroidogenesis. Leydig cell steroidogenesis then passively decreases following the rapid degradation of cAMP into AMP by phosphodiesterases. In this study, we show that AMP-activated protein kinase (AMPK) is activated following cAMP breakdown in MA-10 and MLTC-1 Leydig cells. Activated AMPK then actively inhibits cAMP-induced steroidogenesis by repressing the expression of key regulators of steroidogenesis including Star and Nr4a1. Similar results were obtained in Y-1 adrenal cells and in the constitutive steroidogenic cell line R2C. Our data identify AMPK as an active repressor of steroid hormone biosynthesis in steroidogenic cells that is essential to preserve cellular energy and prevent excess steroid production. Steroid hormones regulate essential physiological processes and inadequate levels are associated with various pathological conditions. In testosterone-producing Leydig cells, steroidogenesis is strongly stimulated by LH via its receptor leading to increased cAMP production and expression of the steroidogenic acute regulatory (STAR) protein, which is essential for the initiation of steroidogenesis. Leydig cell steroidogenesis then passively decreases following the rapid degradation of cAMP into AMP by phosphodiesterases. In this study, we show that AMP-activated protein kinase (AMPK) is activated following cAMP breakdown in MA-10 and MLTC-1 Leydig cells. Activated AMPK then actively inhibits cAMP-induced steroidogenesis by repressing the expression of key regulators of steroidogenesis including Star and Nr4a1. Similar results were obtained in Y-1 adrenal cells and in the constitutive steroidogenic cell line R2C. Our data identify AMPK as an active repressor of steroid hormone biosynthesis in steroidogenic cells that is essential to preserve cellular energy and prevent excess steroid production. MA-10 Leydig cells were treated with either DMSO (control), 10 uM forskolin or forskolin+Aicar (1 mM) for 1.5 h before total RNA extraction

Project description:Steroid hormones regulate essential physiological processes and inadequate levels are associated with various pathological conditions. In testosterone-producing Leydig cells, steroidogenesis is strongly stimulated by LH via its receptor leading to increased cAMP production and expression of the steroidogenic acute regulatory (STAR) protein, which is essential for the initiation of steroidogenesis. Leydig cell steroidogenesis then passively decreases following the rapid degradation of cAMP into AMP by phosphodiesterases. In this study, we show that AMP-activated protein kinase (AMPK) is activated following cAMP breakdown in MA-10 and MLTC-1 Leydig cells. Activated AMPK then actively inhibits cAMP-induced steroidogenesis by repressing the expression of key regulators of steroidogenesis including Star and Nr4a1. Similar results were obtained in Y-1 adrenal cells and in the constitutive steroidogenic cell line R2C. Our data identify AMPK as an active repressor of steroid hormone biosynthesis in steroidogenic cells that is essential to preserve cellular energy and prevent excess steroid production. Steroid hormones regulate essential physiological processes and inadequate levels are associated with various pathological conditions. In testosterone-producing Leydig cells, steroidogenesis is strongly stimulated by LH via its receptor leading to increased cAMP production and expression of the steroidogenic acute regulatory (STAR) protein, which is essential for the initiation of steroidogenesis. Leydig cell steroidogenesis then passively decreases following the rapid degradation of cAMP into AMP by phosphodiesterases. In this study, we show that AMP-activated protein kinase (AMPK) is activated following cAMP breakdown in MA-10 and MLTC-1 Leydig cells. Activated AMPK then actively inhibits cAMP-induced steroidogenesis by repressing the expression of key regulators of steroidogenesis including Star and Nr4a1. Similar results were obtained in Y-1 adrenal cells and in the constitutive steroidogenic cell line R2C. Our data identify AMPK as an active repressor of steroid hormone biosynthesis in steroidogenic cells that is essential to preserve cellular energy and prevent excess steroid production.

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A genome-wide expression profile of steroidogenic cells selectively isolated from adrenal glands of knockout mice lacking steroidogenic acute regulatory protein

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