The first step in the biosynthesis of steroid hormones is conversion of cholesterol into pregnenolone. StAR (steroidogenic acute regulatory) protein plays a crucial role in the intra-mitochondrial movement of cholesterol. STS (steroid sulphatase), which is present ubiquitously in mammalian tissues, including the placenta, adrenal gland, testis and ovary, desulphates a number of 3β-hydroxysteroid sulphates, including cholesterol sulphate. The present study was designed to examine the effect of STS on StAR protein synthesis and steroidogenesis in cells. Steroidogenic activities of COS-1 cells that had been co-transfected with a vector for the cholesterol P450scc (cytochrome P450 side-chain-cleavage enzyme) system, named F2, a StAR expression vector (pStAR), and an STS expression vector (pSTS) were assayed. Whole-cell extracts were subjected to SDS/PAGE and then to Western blot analysis. pSTS co-expressed in COS-1 cells with F2 and pStAR increased pregnenolone synthesis 2-fold compared with that of co-expression with F2 and pStAR. Western blot analysis using COS-1 cells that had been co-transfected with pSTS, F2 and pStAR revealed that StAR protein levels increased, whereas STS and P450scc protein levels did not change. The amount of StAR protein translation products increased when pSTS was added to an in vitro transcription–translation reaction mixture. Pulse–chase experiments demonstrated that the 37 kDa StAR pre-protein disappeared significantly (P<0.01) more slowly in COS-1 cells that had been transfected with pSTS than in COS-1 cells that had not been transfected with pSTS. The increase in StAR protein level is not a result of an increase in StAR gene expression, but is a result of both an increase in translation and a longer half-life of the 37 kDa pre-StAR protein. In conclusion, STS increases StAR protein expression level and stimulates steroid production.
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Research Article|
May 15 2004
The potential function of steroid sulphatase activity in steroid production and steroidogenic acute regulatory protein expression Available to Purchase
Teruo SUGAWARA;
Teruo SUGAWARA
1
*Department of Biochemistry, Hokkaido University Graduate School of Medicine, Kita-ku, Kita 15, Nishi 7, Sapporo 060-8638, Japan
1To whom correspondence should be addressed (e-mail [email protected]).
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Seiichiro FUJIMOTO
Seiichiro FUJIMOTO
†Department of Obstetrics and Gynecology, Hokkaido University Graduate School of Medicine, Kita-ku, Kita 15, Nishi 7, Sapporo 060-8638, Japan
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Publisher: Portland Press Ltd
Received:
September 10 2003
Revision Received:
January 27 2004
Accepted:
February 18 2004
Accepted Manuscript online:
February 18 2004
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2004
2004
Biochem J (2004) 380 (1): 153–160.
Article history
Received:
September 10 2003
Revision Received:
January 27 2004
Accepted:
February 18 2004
Accepted Manuscript online:
February 18 2004
Citation
Teruo SUGAWARA, Seiichiro FUJIMOTO; The potential function of steroid sulphatase activity in steroid production and steroidogenic acute regulatory protein expression. Biochem J 15 May 2004; 380 (1): 153–160. doi: https://doi.org/10.1042/bj20031379
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