[Homocysteine induces macrophage inflammatory protein-1alpha expression by activating NF-kappaB in THP-1 monocytes].
OBJECTIVE
To investigate the effect of homocysteine (HCY) on activation of nuclear factor (NF-kappaB) and inhibitory factor IkappaB-alpha in human monocyte cell line THP-1, as well as its association with macrophage inflammatory protein (MIP-1alpha) upregulation.


METHODS
THP-1 monocytes were incubated with HCY, with and without NF-kappaB inhibitor pyrolidine dithiocarbamate (PDTC) pretreatment. Northern blot analysis and flow cytometry were used to detect MIP-1alpha mRNA and protein respectively. The nuclear protein NF-kappaB P65 subunit and the inhibitory protein IkappaB-alpha were analyzed by Western blotting.


RESULTS
Compared with controls, HCY, at a concentration of 0.1 mmol/L, was able to enhance the expression of MIP-1alpha mRNA (up to 3.69-fold) and protein (1.16-fold) in THP-1 monocytes, as well as enhance NF-kappaB P65 transcription to nuclear proteins. These actions were significantly suppressed after pretreatment with 100 micromol/L PDTC for 30 minutes before HCY incubation; whereas incubation of THP-1 monocytes with PDTC only had no effect on both the expression of MIP-1alpha and nuclear transcription of NF-kappaB P65. Moreover, the level of IkappaB-alpha protein in THP-1 monocytes decreased after a 30-minute incubation with HCY, which gradually increased after 120 minutes.


CONCLUSIONS
Homocysteine at a pathologic concentration stimulates MIP-1alpha expression in THP-1 monocytes, probably via NF-kappaB activation. Such activation may be caused by enhanced phosphorylation and degradation of the inhibitor protein IkappaB-alpha.
Xing
Wei
W
Department of Pathology, Tongji Medical College, Huazhong University of Science Technology, Wuhan 430030, China. grace_xingw@yahoo.com.cn
Deng
Zhong-Duan
ZD
Qu
Zhi-Ling
ZL
Ni
Juan
J
D045744:Cell Line, Tumor; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D006710:Homocysteine / Q000494:pharmacology*; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D007948:Leukemia, Monocytic, Acute / Q000378:metabolism* / Q000473:pathology; D019402:Macrophage Inflammatory Proteins / Q000096:biosynthesis* / Q000235:genetics; D009000:Monocytes / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D011392:Proline / Q000031:analogs & derivatives / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D013859:Thiocarbamates / Q000494:pharmacology; D051996:Transcription Factor RelA / Q000096:biosynthesis* / Q000235:genetics; D014158:Transcription, Genetic
D054405:Chemokine CCL3; D054407:Chemokine CCL4; D020672:I-kappa B Proteins; D019402:Macrophage Inflammatory Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D012333:RNA, Messenger; D013859:Thiocarbamates; D051996:Transcription Factor RelA; D006710:Homocysteine; C066229:prolinedithiocarbamate; D000072000:NF-KappaB Inhibitor alpha; D011392:Proline