Effect of tumor necrosis factor-α on acyl coenzyme A: cholesteryl acyltransferase activity and ACAT1 gene expression in THP-1 macrophages

Abstract

In order to explore the effect and mechanisms of tumor necrosis factor-α (TNF-α) on the activity of the acyl coenzyme A: cholesteryl acyltransferase (ACAT), THP-1 monocytes were cultured and induced to differentiate into macrophages with phorbol ester. TNF-α (60 ng/mL) was added at different time points into the macrophage-containing medium and the ACAT enzyme activity was measured by quantifying the incorporation of [1-¹⁴C] oleoyl CoA into cholesteryl esters. The expression of ACAT-1 protein and mRNA was respectively detected by Western blotting and RT-PCR in THP-1 macrophages 24 h after treatment with TNF-α (60 ng/mL). The results indicated that ACAT activity in THP-1 macrophages treated with TNF-α was increased in a time-dependent manner. The expression levels of ACAT-1 protein and mRNA were significantly increased in THP-1 macrophages after treatment with TNF-α (P<0.05). It was suggested that TNF-α could increase the activity of ACAT in THP-1 macrophages by up-regulating the expression of ACAT-1 gene.

Keywords

acyl coenzyme A: cholesteryl acyltransferase / tumor necrosis factor-α / macrophages / cholesterol / atherosclerosis

References

[1] KaartinenM., PenttiläA., KovanenP.. Mast cells in rupture-prone areas of human coronary atheromas produce and store TNF-α. Circulation, 1996, 94: 2787-2792

[2] Lopes-VirellaM., VirellaG.. Cytokines, modified lipoproteins, and arteriosclerosis in diabetes. Diabetes, 1996, 45(Suppl3): S40-S44

[3] TsouknosA., NashG. B., RaingerG. E.. Monocytes initiate a cycle of leukocyte recruitment when cocultured with endothelial cells. Atherosclerosis, 2003, 170(1): 49-58

[4] ZhangW. J., FreiB.. Intracellular metal ion chelators inhibit TNF alpha-induced SP-1 activation and adhesion molecule expression in human aortic endothelial cells. Free Radic Biol Med, 2003, 34(6): 674-682

[5] ShibasakiM., TakahashiK., ItouT., et al.. A PPAR agonist improves TNF-alpha-induced insulin resistance of adipose tissue in mice. Biochem Biophys Res Commun, 2003, 309(2): 419-424

[6] HardardottirI., MoserA. H., FullerJ., et al.. Endotoxin and cytokines decrease serum levels and extra hepatic protein and mRNA levels of cholesteryl ester transfer protein in syrian hamsters. J Clin Invest, 1996, 97(11): 2585-2592

[7] SiwikD. A., ChangD. L. F., ColucciW. S.. Interleukin-1β and tumor necrosis factor-α decrease collagen synthesis and increase matrix metalloproteinase activity in vitro. Circ Res, 2000, 86: 1259-1265

[8] BuhmanK. F., AccadM., FareseR. V.. Mammalian acyl-CoA: cholesterol acyltransferases. Biochi Biophy Acta, 2000, 1529: 142-154

[9] SakashitaN., MiyazakiA., TakeyaM., et al.. Localization of human acyl-coenzyme A: cholesterol acyltransferase-1 (ACAT-1) in macrophages and in various tissues. Am J Pathol, 2000, 156(1): 227-236

[10] SmithJ. L., RangarajK., SimpsonR., et al.. Quantitative analysis of expression of ACAT genes in human tissues by real-time PCR. J Lip Res, 2004, 45: 686-696

[11] WangH. X., GermainS. J., BenfieldP. P., et al.. Gene expression of acyl coenzyme A: cholesterol acyltransferase is upregulated in human monocytes during differentiation and foam cell formation. Arterioscler Thromb Vasc Biol, 1996, 16: 809-814

[12] MiyazakiA., SakashitaN., LeeO., et al.. Expression of ACAT-1 protein in human atherosclerotic lesions and cultured human monocytes-macrophages. Arterioscler Thromb Vasc Biol, 1998, 18(10): 1568-1574

[13] ChatterjeeS.. Neutral sphingomyelinase action stimulates signal transduction of tumor necrosis factor-alpha in the synthesis of cholesteryl esters in human fibroblasts. J Biol Chem, 1994, 269: 879-882

[14] BillheimerJ. T., GilliesP. J.. Advances in Cholesterol Research, 1990, Caldwell, Telford Press: 7-45

[15] ChangT. Y., LimanekJ. S., ChangC. C. Y.. A simple and efficient procedure for the rapid homogenization of cultured animal cells grown in monolayer. Anal Biochem, 1981, 116: 298-302

[16] SchwendeH., FitzkeE., AmbsP., et al.. Differences in the state of differentiation of THP-1 cells induced by phorbol ester and 1,25-dihydroxyvitamin D3. J Leukoc Biol, 1996, 59(4): 555-561