Steroids, essential for mammalian survival, are initiated by cholesterol transport by steroidogenic acute regulatory protein (StAR). Appropriate protein folding is an essential requirement of activity. Endoplasmic reticulum (ER) chaperones assist in folding of cytoplasmic proteins, whereas mitochondrial chaperones fold only mitochondrial proteins. We show that glucose regulatory protein 78 (GRP...

StAR (steroidogenic acute regulatory) proteins and proteins with StAR-related lipid transfer (START) domains are involved in lipid transport and metabolism, signal transduction, and transcriptional regulation. In this present study we characterized the StARD9 gene by bioinformatical methods. The human StARD9 gene (syn. KIAA1300), consisting of 11 exons, was located within human genome sequence ...

Growth factors are known to play diverse roles in steroidogenesis, a process regulated by the mitochondrial steroidogenic acute regulatory (StAR) protein. The mechanism of action of one such growth factor, IGF-I, was investigated in mouse Leydig tumor (mLTC-1) cells to determine its potential role in the regulation of StAR expression. mLTC-1 cells treated with IGF-I demonstrated temporal and co...

DAX-1 is an unusual member of the nuclear hormone receptor superfamily whose expression is mainly, but not uniquely, restricted to steroidogenic tissues. We have recently shown that DAX-1 can block the first and rate-limiting step in steroid biosynthesis by repressing StAR (steroidogenic acute regulatory protein) expression. Here we show that DAX-1 blocks steroid production at multiple levels i...

Background: Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders, affecting 5-10% of reproductive aged women. High levels of androgen hormone can be accounted as the most important symptoms in PCOS. Androgen is the precursor of steroid biosynthesis in ovary. The transport of cholesterol to the inner mitochondrial membrane through StAR protein is also necessary for andr...

Objective PCOS is the most frequent female endocrine disorder, affecting 5%-10% of women, is characterized by hyperandrogenism, oligo-/anovulation, and polycystic ovaries. The aim of the present research is to evaluate the expression of steroidogenic acute regulatory protein (StAR) and CYP19 (aromatase) mRNA in the ovary of EV-induced PCOS rat model and the effect of the treadmill and running w...

Cholesterol is the obligate precursor to adrenal steroids but is cytotoxic at high concentrations. Here, we show the role of the liver X receptors (LXRalpha and LXRbeta) in preventing accumulation of free cholesterol in mouse adrenal glands by controlling expression of genes involved in all aspects of cholesterol utilization, including the steroidogenic acute regulatory protein, StAR, a novel L...

Steroidogenic acute regulatory protein (StAR) is essential for adrenal and gonadal steroidogenesis, stimulating the translocation of cholesterol to the inner mitochondrial membrane where steroidogenesis commences. StAR mutations in humans cause congenital lipoid adrenal hyperplasia (lipoid CAH), an autosomal recessive condition with severe deficiencies of all classes of steroid hormones. We pre...