Study of the insulin signaling pathways in the regulation of ACAT1 expression in cultured macrophages.
OBJECTIVE
To determine the signaling pathways and components involved in insulin-mediated regulation of Acyl-CoA: cholesterol acyltransferase1 (ACAT1).


METHODS
THP-1 cells were cultured in RPMI 1640 medium and were induced into macrophages in the presence of 160 nM phorbol 12-myristate 13-acetate (PMA). Before insulin was added in, macrophages were preincubated with the inhibitors of the insulin signaling pathway, including wortmannin, phosphatidylinositol 3-kinase (PI3K) inhibitor; PD98059, extracellular signal-regulated kinase (ERK) inhibitor; SB203580, p38 mitogen-activated protein kinase (p38MAPK) inhibitor; SP600125, c-Jun N-terminal kinase (JNK) inhibitor and U73122, phospholipase C-gamma (PLC-gamma) inhibitor. ACAT1 mRNA and protein expression level in macrophages were determined by real-time quantitative polymerase chain reaction and western blotting, respectively.


RESULTS
Real-time quantitative polymerase chain reaction and western blotting demonstrated that PD98059, SB203580 or SP600125 down-regulated the expression of ACAT1 in a dose-dependent manner. However, no obvious alteration was found in wortmannin and U73122 groups.


CONCLUSIONS
These results suggest that the ERK, p38MAPK and JNK signaling pathways may be involved in insulin-mediated regulation of ACAT1, but no PI3K and PLC-gamma signaling pathways were involved in the present study.
Xin
Chen
C
Geriatric Department, Renmin Hospital of Wuhan University, Wuhan, China.
Yan-Fu
Wang
W
Ping
He
H
Jing
Ge
G
Jing-Jing
Wan
W
Chun-Li
Mei
M
Wei
Liu
L
Bei
Cheng
C
D000818:Animals; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051966:Phospholipase C gamma / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D002785:Sterol O-Acyltransferase / Q000235:genetics / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
D004791:Enzyme Inhibitors; D048049:Extracellular Signal-Regulated MAP Kinases; D007328:Insulin; D048031:JNK Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051966:Phospholipase C gamma; D002785:Sterol O-Acyltransferase; D048051:p38 Mitogen-Activated Protein Kinases