HIV protease inhibitor lopinavir-induced TNF-alpha and IL-6 expression is coupled to the unfolded protein response and ERK signaling pathways in macrophages.
HIV protease inhibitor (PI)-associated cardiovascular risk, especially atherosclerosis, has become a major concern in the clinic. Macrophages are key players in the inflammatory response and atherosclerosis formation. We have previously shown that HIV PIs induce endoplasmic reticulum (ER) stress, activate the unfolded protein response (UPR), and increase the synthesis of the inflammatory cytokines, TNF-alpha and IL-6, by regulating the intracellular translocation of RNA binding protein HuR in macrophages. However, the underlying signaling mechanisms remain unclear. We show here that the HIV PI lopinavir significantly activated the extracellular-signal regulated protein kinase (ERK), but not c-Jun N-terminal kinase (JNK) and p38 MAPK. Lopinavir-induced cytosolic translocation of HuR and TNF-alpha and IL-6 synthesis was attenuated by specific chemical inhibitor of MEK (PD98058) or over-expression of dominant negative mutant of MEK1. In addition, we demonstrated that lopinavir-induced ERK activation and TNF-alpha and IL-6 expression were completely inhibited in macrophages from CHOP null mice. Taken together, these results indicate activation of the UPR plays an essential role in HIV PI-induced inflammatory cytokine synthesis and release by activating ERK, which increases the cytosolic translocation of HuR and subsequent binding to the 3'UTR of TNF-alpha and IL-6 mRNAs in macrophages.
Chen
Li
L
Department of Microbiology & Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA.
Jarujaron
Sirikalaya
S
Wu
Xudong
X
Sun
Lixin
L
Zha
Weibin
W
Liang
Guang
G
Wang
Xuan
X
Gurley
Emily C
EC
Studer
Elaine J
EJ
Hylemon
Phillip B
PB
Pandak
William M
WM
Zhang
Luyong
L
Wang
Guangji
G
Li
Xiaokun
X
Dent
Paul
P
Zhou
Huiping
H
D000818:Animals; D045744:Cell Line, Tumor; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D017320:HIV Protease Inhibitors / Q000494:pharmacology*; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics*; D007948:Leukemia, Monocytic, Acute; D061466:Lopinavir; D020935:MAP Kinase Signaling System; D008264:Macrophages / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D016328:NF-kappa B / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011489:Protein Denaturation; D011744:Pyrimidinones / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
D017320:HIV Protease Inhibitors; D015850:Interleukin-6; D016328:NF-kappa B; D011744:Pyrimidinones; D014409:Tumor Necrosis Factor-alpha; D061466:Lopinavir; D019869:Phosphatidylinositol 3-Kinases; D048049:Extracellular Signal-Regulated MAP Kinases