The involvement of epoxygenase metabolites of arachidonic acid in cAMP-stimulated steroidogenesis and steroidogenic acute regulatory protein gene expression.
The essential role of arachidonic acid (AA) in steroidogenesis has been previously demonstrated. The present study continues the investigation into how AA regulates steroidogenesis by examining the effects of epoxygenase-derived AA metabolites on cAMP-stimulated steroidogenic acute regulatory (StAR) gene expression and steroid hormone production in MA-10 mouse Leydig cells. The HPLC analysis of cell extracts from MA-10 cells treated with the cAMP analog dibutyryl cAMP (dbcAMP) demonstrated an increase in three epoxygenase-generated AA metabolites: 5,6-epoxyeicosatrienoic acid (EET), 8,9-EET, and 11,12-EET. Incubating MA-10 cells with each of the EETs induced a dose-dependent increase in StAR protein expression and steroid hormone production in the presence of dbcAMP. These metabolites also significantly enhanced StAR gene transcription as determined by luciferase assays of StAR promoter activity and reverse transcriptase-PCR analysis of StAR mRNA levels. While the EETs enhanced steroidogenesis, inhibiting the activity of protein kinase A (PKA) abolished the stimulatory effects of these AA metabolites on StAR expression and steroid hormone production. This study suggests that cAMP stimulation of MA-10 cells increases epoxygenase-generated AA metabolites and the co-action of these metabolites with PKA significantly increases StAR gene expression and steroid hormone production.
Wang
Xingjia
X
Department of Neuropsychiatry, Garrison Institute on Aging, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA. xingjia.wang@ttuhsc.edu
Shen
Chwan-Li
CL
Dyson
Matthew T
MT
Yin
Xianling
X
Schiffer
Randolph B
RB
Grammas
Paula
P
Stocco
Douglas M
DM
D015126:8,11,14-Eicosatrienoic Acid / Q000378:metabolism*; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D015153:Blotting, Western / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D000242:Cyclic AMP / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D010750:Phosphoproteins / Q000235:genetics*; D011374:Progesterone / Q000096:biosynthesis; D012333:RNA, Messenger / Q000032:analysis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013268:Stimulation, Chemical; D014162:Transfection / Q000379:methods; D000098682:Steroidogenic Acute Regulatory Protein
D010750:Phosphoproteins; D012333:RNA, Messenger; D000098682:Steroidogenic Acute Regulatory Protein; D016718:Arachidonic Acid; D011374:Progesterone; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D015126:8,11,14-Eicosatrienoic Acid