title: Downregulation of steroidogenic acute regulatory protein (StAR) gene expression by cyclic AMP in cultured Schwann cells.
abstract: Steroidogenic acute regulatory protein (StAR) plays a key role in the availability of cholesterol to the inner mitochondrial membrane, where the first step of steroidogenesis, its conversion to pregnenolone, takes place. Here, we demonstrate for the first time that the StAR gene is also expressed in the rat sciatic nerve and in cultured Schwann cells. The addition to the culture medium of the cAMP-elevating agent forskolin or of the cAMP analogue 8Br-cAMP produced a time-course extinction of StAR gene expression. An inverse relationship was demonstrated between StAR gene expression and the intracellular cAMP content. Accordingly, pharmacological inhibition of the activities of Schwann cell adenylyl cyclase or of phosphodiesterase IV resulted in modifications of StAR gene expression. Since StAR gene expression is stimulated by cAMP in classical steroidogenic cells, our work is the first demonstration of a negative regulation of StAR gene by cAMP.
authors.affiliation: INSERM U488, Kremlin-Bicêtre, France.
authors.forename: Yasmina
authors.initials: Y
authors.lastname: Benmessahel
authors.forename: Jean-Denis
authors.initials: JD
authors.lastname: Troadec
authors.forename: Françoise
authors.initials: F
authors.lastname: Cadepond
authors.forename: Rachida
authors.initials: R
authors.lastname: Guennoun
authors.forename: Dale Buchanan
authors.initials: DB
authors.lastname: Hales
authors.forename: Michael
authors.initials: M
authors.lastname: Schumacher
authors.forename: Ghislaine
authors.initials: G
authors.lastname: Groyer
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology*; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D010750:Phosphoproteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D012583:Schwann Cells / Q000187:drug effects / Q000378:metabolism*; D012584:Sciatic Nerve / Q000378:metabolism; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: D010750:Phosphoproteins; D012333:RNA, Messenger; D000098682:Steroidogenic Acute Regulatory Protein; D005576:Colforsin; D000242:Cyclic AMP