Stimulation of steroidogenic acute regulatory protein (STAR) gene expression by D-aspartate in rat Leydig cells

FEBS Letters ◽  
1999 ◽  
Vol 454 (3) ◽  
pp. 317-320 ◽  
Keyword(s):  
Gene Expression ◽  
Leydig Cells ◽  
Regulatory Protein ◽  
Steroidogenic Acute Regulatory Protein ◽  
Steroidogenic Acute Regulatory ◽  
Star Gene ◽  
Stimulation Of

scholarly journals Porcine and Bovine Steroidogenic Acute Regulatory Protein (StAR) Gene Expression during Gestation1

Endocrinology ◽  
1997 ◽  
Vol 138 (3) ◽  
pp. 1085-1091 ◽  
Author(s):  
Nicolas Pilon ◽  
Isabelle Daneau ◽  
Chantal Brisson ◽  
Jean-François Ethier ◽  
Jacques G. Lussier ◽  
...  
Keyword(s):  
Gene Expression ◽  
Regulatory Protein ◽  
Steroidogenic Acute Regulatory Protein ◽  
Steroidogenic Acute Regulatory ◽  
Star Gene

scholarly journals Synergistic Activation of Steroidogenic Acute Regulatory Protein Expression and Steroid Biosynthesis by Retinoids: Involvement of cAMP/PKA Signaling

Endocrinology ◽  
2014 ◽  
Vol 155 (2) ◽  
pp. 576-591 ◽  
Author(s):  
Pulak R. Manna ◽  
Andrzej T. Slominski ◽  
Steven R. King ◽  
Cloyce L. Stetson ◽  
Douglas M. Stocco
Keyword(s):  
Retinoic Acid ◽  
Leydig Cells ◽  
Binding Protein ◽  
Regulatory Protein ◽  
Liver X Receptor ◽  
Steroidogenic Acute Regulatory Protein ◽  
Type I ◽  
Steroid Biosynthesis ◽  
Steroidogenic Acute Regulatory ◽  
Star Gene

Both retinoic acid receptors (RARs) and retinoid X receptors (RXRs) mediate the action of retinoids that play important roles in reproductive development and function, as well as steroidogenesis. Regulation of steroid biosynthesis is principally mediated by the steroidogenic acute regulatory protein (StAR); however, the modes of action of retinoids in the regulation of steroidogenesis remain obscure. In this study we demonstrate that all-trans retinoic acid (atRA) enhances StAR expression, but not its phosphorylation (P-StAR), and progesterone production in MA-10 mouse Leydig cells. Activation of the protein kinase A (PKA) cascade, by dibutyrl-cAMP or type I/II PKA analogs, markedly increased retinoid-responsive StAR, P-StAR, and steroid levels. Targeted silencing of endogenous RARα and RXRα, with small interfering RNAs, resulted in decreases in 9-cis RA-stimulated StAR and progesterone levels. Truncation of and mutational alterations in the 5′-flanking region of the StAR gene demonstrated the importance of the −254/−1-bp region in retinoid responsiveness. An oligonucleotide probe encompassing an RXR/liver X receptor recognition motif, located within the −254/−1-bp region, specifically bound MA-10 nuclear proteins and in vitro transcribed/translated RXRα and RARα in EMSAs. Transcription of the StAR gene in response to atRA and dibutyrl-cAMP was influenced by several factors, its up-regulation being dependent on phosphorylation of cAMP response-element binding protein (CREB). Chromatin immunoprecipitation studies revealed the association of phosphorylation of CREB, CREB binding protein, RXRα, and RARα to the StAR promoter. Further studies elucidated that hormone-sensitive lipase plays an important role in atRA-mediated regulation of the steroidogenic response that involves liver X receptor signaling. These findings delineate the molecular events by which retinoids influence cAMP/PKA signaling and provide additional and novel insight into the regulation of StAR expression and steroidogenesis in mouse Leydig cells.

scholarly journals MEF2 Cooperates With Forskolin/cAMP and GATA4 to Regulate Star Gene Expression in Mouse MA-10 Leydig Cells

Endocrinology ◽  
2015 ◽  
Vol 156 (7) ◽  
pp. 2693-2703 ◽  
Author(s):  
Caroline Daems ◽  
Mickaël Di-Luoffo ◽  
Élise Paradis ◽  
Jacques J. Tremblay
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Leydig Cells ◽  
Regulatory Protein ◽  
Mrna Levels ◽  
Small Interfering Rnas ◽  
Inner Mitochondrial Membrane ◽  
Protein Levels ◽  
Steroidogenic Acute Regulatory ◽  
Star Gene

In Leydig cells, steroidogenic acute regulatory protein (STAR) participates in cholesterol shuttling from the outer to the inner mitochondrial membrane, the rate-limiting step in steroidogenesis. Steroid hormone biosynthesis and steroidogenic gene expression are regulated by LH, which activates various signaling pathways and transcription factors, including cAMP/Ca2+/CAMK (Ca2+/calmodulin-dependent kinase)–myocyte enhancer factor 2 (MEF2). The 4 MEF2 transcription factors are essential regulators of cell differentiation and organogenesis in numerous tissues. Recently, MEF2 was identified in Sertoli and Leydig cells of the testis. Here, we report that MEF2 regulates steroidogenesis in mouse MA-10 Leydig cells by acting on the Star gene. In MA-10 cells depleted of MEF2 using siRNAs (small interfering RNAs), STAR protein levels, Star mRNA levels, and promoter activity were significantly decreased. On its own, MEF2 did not activate the mouse Star promoter but was found to cooperate with forskolin/cAMP. By chromatin immunoprecipitation and DNA precipitation assays, we confirmed MEF2 binding to a consensus element located at −232 bp of the Star promoter. Mutation or deletion of the MEF2 element reduced but did not abrogate the MEF2/cAMP cooperation, indicating that MEF2 cooperates with other DNA-bound transcription factor(s). We identified GATA4 (GATA binding protein 4) as a partner for MEF2 in Leydig cells, because mutation of the GATA element abrogated the MEF2/cAMP cooperation on a reporter lacking a MEF2 element. MEF2 and GATA4 interact as revealed by coimmunoprecipitation, and MEF2 and GATA4 transcriptionally cooperate on the Star promoter. Altogether, our results define MEF2 as a novel regulator of steroidogenesis and Star transcription in Leydig cells and identify GATA4 as a key partner for MEF2-mediated action.

scholarly journals Chrysin, a natural flavonoid enhances steroidogenesis and steroidogenic acute regulatory protein gene expression in mouse Leydig cells

2008 ◽  
Vol 197 (2) ◽  
pp. 315-323 ◽  
Author(s):  
Kuladip Jana ◽  
Xiangling Yin ◽  
Randolph B Schiffer ◽  
Jau-Jiin Chen ◽  
Akhilesh K Pandey ◽  
...  
Keyword(s):  
Gene Expression ◽  
Leydig Cells ◽  
Steroid Hormone ◽  
Mrna Level ◽  
Regulatory Protein ◽  
Threshold Level ◽  
Star Protein ◽  
Chain Cleavage ◽  
Steroidogenic Acute Regulatory ◽  
Star Gene

During the aging process of males, testosterone biosynthesis declines in testicular Leydig cells resulting in decreases in various physiological functions. To explore the possibility of delaying the decline using food supplements, we have studied steroidogenic effects of a natural flavonoid, chrysin, in mouse Leydig cells. Chrysin dramatically increased cyclic AMP (cAMP)-induced steroidogenesis in MA-10 mouse Leydig tumor cells. This result was confirmed using Leydig cells isolated from mouse testes. The steroidogenic effect of chrysin is not associated with an increase in expression of the P450 side-chain cleavage enzyme, required for the conversion of cholesterol to pregnenolone. In addition, when 22(R)hydroxylcholesterol was used as a substrate, chrysin induced a non-significant increase in steroid hormone, suggesting that the majority of the observed increase in steroidogenesis was due to the increased supply of substrate cholesterol. These observations were corroborated by showing that chrysin induced a marked increase in the expression of steroidogenic acute regulatory (StAR) protein, the factor that controls mitochondrial cholesterol transfer. Also, chrysin significantly increased StAR promoter activity and StAR mRNA level. Further studies indicated that this compound depressed expression of DAX-1, a repressor in StAR gene transcription. In the absence of cAMP, chrysin did not increase steroidogenesis. However, when a sub-threshold level of cAMP was used, StAR protein and steroid hormone were increased by chrysin to the levels seen with maximal stimulation of cAMP. These results suggest that while chrysin itself is unable to induce StAR gene expression and steroidogenesis, it appears to function by increasing the sensitivity of Leydig cells to cAMP stimulation.

Downregulation of steroidogenic acute regulatory protein (StAR) gene expression by cyclic AMP in cultured Schwann cells

Glia ◽  
2004 ◽  
Vol 45 (3) ◽  
pp. 213-228 ◽  
Author(s):  
Yasmina Benmessahel ◽  
Jean-Denis Troadec ◽  
Fran�oise Cadepond ◽  
Rachida Guennoun ◽  
Dale Buchanan Hales ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cyclic Amp ◽  
Schwann Cells ◽  
Regulatory Protein ◽  
Steroidogenic Acute Regulatory Protein ◽  
Cultured Schwann Cells ◽  
Steroidogenic Acute Regulatory ◽  
Star Gene

scholarly journals DAX-1 Expression in Human Adrenocortical Neoplasms: Implications for Steroidogenesis

1998 ◽  
Vol 83 (7) ◽  
pp. 2597-2600 ◽  
Author(s):  
M. Reincke ◽  
F. Beuschlein ◽  
E. Lalli ◽  
W. Arlt ◽  
S. Vay ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mrna Expression ◽  
Protein Gene ◽  
Regulatory Protein ◽  
Nuclear Hormone Receptor ◽  
Adrenocortical Tumors ◽  
Steroidogenic Acute Regulatory ◽  
Adrenocortical Carcinomas ◽  
Star Gene ◽  
Functional Phenotype

The DAX-1 gene encodes an orphan nuclear hormone receptor essential for normal fetal development of the adrenal cortex. Recently, DAX-1 has been shown to act as a transcriptional repressor of steroidogenic acute regulatory protein gene expression (StAR), suppressing steroidogenesis. We, therefore, investigated the expression of DAX-1 in a variety of adrenocortical tumors and compared the results with StAR mRNA expression. We found low or absent DAX-1 expression in aldosterone-producing adenomas (n=11: 35±11%; normal adrenals: 100±17%) and in aldosterone-producing adrenocortical carcinomas (n=2: 24 and 36%). Cortisol-producing adenomas showed intermediate DAX-1 expression (n=8; 92±16), as did 3 non-aldosterone-producing carcinomas (72, 132 and 132%). High DAX-1 expression was present in nonfunctional adenomas (n=3; 160±17%). In contrast to DAX-1, StAR mRNA expression did not show significant variations between groups. We did not detect the expected negative correlation between DAX-1 and StAR mRNA in adrenocortical tumors. These data suggest that high DAX-1 expression in adrenocortical tumors is associated with a non-functional phenotype whereas low DAX-1 expression favors mineralo-corticoid secretion. These effects on steroidogenesis are mediated by mechanisms other than repression of StAR gene expression. Our results indicate that DAX-1 may be one of the factors influencing the steroid biosynthesis of adrenocortical neoplasms.

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