Induction of acyl-coenzyme A:cholesterol acyltransferase-1 by 1,25-dihydroxyvitamin D(3) or 9-cis-retinoic acid in undifferentiated THP-1 cells.
We have previously shown that acyl-coenzyme A: cholesterol acyltransferase-1 (ACAT-1) protein content increases significantly during the human monocyte-macrophage differentiation process. To gain further insight, we used undifferentiated human monocytic THP-1 cells as a model system with which to examine whether ACAT-1 mRNA and protein content can be increased by treating cells with 1,25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)] or with 9-cis-retinoic acid (9-cis-RA), two agents known to upregulate the expression of various genes during the monocyte-macrophage differentiation process. Immunoblot analysis with anti-human ACAT-1 antibodies revealed that ACAT-1 protein was increased by 2.6-fold, using 1,25-(OH)(2)D(3) at a physiological concentration (100 pM). ACAT-1 protein was also increased when using 9-cis-RA, but only at relatively high concentrations (0.1;-1 microM). Northern blot analysis revealed that among the four ACAT-1 mRNA transcripts (2.8, 3.6, 4.2, and 7.0 kb) examined, only the 2.8- and 3.6-kb transcripts were selectively increased. On the basis of enzyme assays in vitro, ACAT activity was increased 3.0-fold by using 100 nM 1,25-(OH)(2)D(3), and 1.8-fold by using 1 microM 9-cis-RA. Together, our results suggest that 1,25-(OH)(3) participates in ACAT-1 gene expression during the monocyte-macrophage differentiation process.
Maung
K
K
Department of Biochemistry, Kumamoto University School of Medicine, 2-2-1 Honjo, Kumamoto 860-0811, Japan.
Miyazaki
A
A
Nomiyama
H
H
Chang
C C
CC
Chang
T Y
TY
Horiuchi
S
S
D000077556:Alitretinoin; D001483:Base Sequence; D015152:Blotting, Northern; D002117:Calcitriol / Q000494:pharmacology*; D002454:Cell Differentiation; D002460:Cell Line; D017931:DNA Primers; D004790:Enzyme Induction; D006801:Humans; D009000:Monocytes / Q000187:drug effects* / Q000201:enzymology; D012333:RNA, Messenger / Q000235:genetics; D002785:Sterol O-Acyltransferase / Q000096:biosynthesis* / Q000235:genetics; D014212:Tretinoin / Q000494:pharmacology*
D017931:DNA Primers; D012333:RNA, Messenger; D000077556:Alitretinoin; D014212:Tretinoin; D002785:Sterol O-Acyltransferase; D002117:Calcitriol