The effects of inflammatory cytokines on steroidogenic acute regulatory protein expression in macrophages.
OBJECTIVE
To investigate the expression of steroidogenic acute regulatory protein (StAR) in macrophages and the effects of inflammatory cytokines on StAR expression.


METHODS
The macrophages isolated from ApoE knockout mice and C57BL/6J mice and RAW264.7 cells (a cell line from mouse macrophage. ATCC Number: TIB-71) were cultured in DMEM containing 10% fetal bovine serum. RAW264.7 cells were treated with different inflammatory cytokines (TNF-alpha, IFN-gamma and TGF-beta1) and 8-Br-cAMP, a cAMP analog. RT-PCR and Western blot analysis were applied to evaluate the effects of inflammatory cytokines on StAR expression.


RESULTS
RT-PCR and Western blot analysis demonstrated the expression of StAR in the macrophages isolated from ApoE knockout mice, C57BL/6J mice and RAW264.7 cells. Proinflammatory cytokines TNF-alpha and IFN-gamma significantly decreased StAR mRNA and protein levels in RAW264.7 cells. The inhibition was dose- and time-dependent. In contrast, anti-inflammatory cytokine TGF-beta1 increased StAR mRNA and protein levels. At 1:15 molecular ratio, TGF-beta1 blocked the down-regulation of StAR expression mediated by TNF-alpha. cAMP also induced StAR expression in RAW264.7 cells. When the cells were co-treated with 8-Br-cAMP and TNF-alpha, 8-Br-cAMP failed to induce StAR expression.


CONCLUSIONS
Our results provide interesting evidence that inflammatory cytokines regulate StAR expression in macrophages.
Ma
Y
Y
Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, PR China.
Ren
S
S
Pandak
W M
WM
Li
X
X
Ning
Y
Y
Lu
C
C
Zhao
F
F
Yin
L
L
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001057:Apolipoproteins E / Q000235:genetics; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D016207:Cytokines / Q000494:pharmacology* / Q000502:physiology; D005786:Gene Expression Regulation; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010750:Phosphoproteins / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D000098682:Steroidogenic Acute Regulatory Protein
D001057:Apolipoproteins E; D016207:Cytokines; D010750:Phosphoproteins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D000098682:Steroidogenic Acute Regulatory Protein; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000242:Cyclic AMP