Cyclic adenosine 5'-monophosphate-dependent sphingosine-1-phosphate biosynthesis induces human CYP17 gene transcription by activating cleavage of sterol regulatory element binding protein 1.
In the human adrenal cortex, ACTH activates steroid hormone biosynthesis by acutely increasing cholesterol delivery to the mitochondrion and chronically increasing the transcription of steroidogenic genes (including CYP17) via a cAMP-dependent pathway. In the present study, we characterized the role of sphingolipids in ACTH-dependent steroidogenesis. H295R human adrenocortical cells were treated with ACTH or dibutyryl cAMP (Bt2cAMP) and the content of several sphingolipid species quantified by mass spectrometry. Both ACTH and Bt2cAMP decreased cellular amounts of several sphingolipids, including sphingomyelin, ceramides, and sphingosine and stimulating the activity of sphingosine kinase and increasing the release of sphingosine-1-phosphate (S1P) into the media. S1P increased CYP17 mRNA expression by promoting the cleavage and nuclear localization of sterol regulatory element binding protein (SREBP) 1. Chromatin immunoprecipitation assays revealed that Bt2cAMP and S1P increased acetylation of histone H3 and promoted binding of SREBP1 to the -520/-331 region of the CYP17 promoter. In summary, our studies demonstrate a role for sphingolipid metabolism and SREBP1 in ACTH-dependent CYP17 regulation and steroidogenesis.
Ozbay
Tuba
T
School of Biology, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, Georgia 30332-0230, USA.
Rowan
Anne
A
Leon
Adam
A
Patel
Pritty
P
Sewer
Marion B
MB
D015152:Blotting, Northern; D015153:Blotting, Western; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D000242:Cyclic AMP / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006657:Histones / Q000378:metabolism; D006801:Humans; D008055:Lipids / Q000737:chemistry; D008246:Lysophospholipids / Q000378:metabolism*; D013058:Mass Spectrometry; D008954:Models, Biological; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012313:RNA / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013107:Sphingolipids / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism; D013254:Steroid 17-alpha-Hydroxylase / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D051780:Sterol Regulatory Element Binding Protein 1 / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection
D006657:Histones; D008055:Lipids; D008246:Lysophospholipids; D012333:RNA, Messenger; C497387:SREBF1 protein, human; D013107:Sphingolipids; D051780:Sterol Regulatory Element Binding Protein 1; C060506:sphingosine 1-phosphate; D012313:RNA; D000242:Cyclic AMP; D013254:Steroid 17-alpha-Hydroxylase; D013110:Sphingosine