Document Detail

Detection of the steroidogenic acute regulatory protein, StAR, in human liver cells.
MedLine Citation:
PMID:  15863358     Owner:  NLM     Status:  MEDLINE    
Overexpressing StAR (a mitochondrial cholesterol transporter) increases (>5-fold) the rate of 27-hydroxylation of cholesterol and the rates of bile acid synthesis in primary rat hepatocytes; suggesting that the transport of cholesterol into mitochondria is rate-limiting for bile acid biosynthesis via the CYP27A1 initiated 'acidic' pathway. Our objective was to determine the level of StAR expression in human liver and whether changes in StAR would correlate with changes in CYP27A1 activity/bile acid synthesis rates in human liver tissues. StAR mRNA and protein were detected in primary human hepatocytes and HepG2 cells by RT-PCR/Northern analysis and by Western analysis, respectively. In immunocompetition assays, liver StAR was competed away with the addition of purified human adrenal StAR. Overexpressing CYP27A1 in both cell types led to >2-fold increases in liver StAR concentration. StAR protein levels also increased approximately 2-fold with the addition of 27-hydroxycholesterol to HepG2 cell culture medium. Overexpressing StAR increased the rates of 27-hydroxylation of cholesterol/bile acid synthesis in both cell lines and increased intracellular levels of 27-hydroxycholesterol. In conclusion, human liver cells contain regulable StAR protein whose level of expression appears capable of regulating cellular cholesterol homeostasis, representing a potential therapeutic target in the management of hyperlipidemia.
E A Hall; S Ren; P B Hylemon; D Rodriguez-Agudo; K Redford; D Marques; D Kang; G Gil; W M Pandak
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.     Date:  2005-03-02
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  1733     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  2005 Apr 
Date Detail:
Created Date:  2005-05-02     Completed Date:  2005-06-14     Revised Date:  2012-01-30    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  111-9     Citation Subset:  IM    
Department of Medicine, Veterans Affairs Medical Center and Virginia Commonwealth University, Richmond, USA.
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MeSH Terms
Bile Acids and Salts / biosynthesis
Blotting, Western
Cell Line
Cytochrome P-450 CYP27A1
Electrophoresis, Gel, Two-Dimensional
Hepatocytes / chemistry,  metabolism*
Hydroxycholesterols / pharmacology
Liver / chemistry,  metabolism*
Mitochondrial Proteins / metabolism
Phosphoproteins / analysis,  biosynthesis*,  genetics
RNA, Messenger / biosynthesis
Recombinant Proteins / biosynthesis
Steroid Hydroxylases / biosynthesis,  genetics
Grant Support
Reg. No./Substance:
0/Bile Acids and Salts; 0/Hydroxycholesterols; 0/Mitochondrial Proteins; 0/Phosphoproteins; 0/RNA, Messenger; 0/Recombinant Proteins; 0/steroidogenic acute regulatory protein; 20380-11-4/27-hydroxycholesterol; EC 1.14.-/Cytochrome P-450 CYP27A1; EC 1.14.-/Steroid Hydroxylases; EC protein, human

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