| Summary: | 碩士 === 國立陽明大學 === 生化暨分子生物研究所 === 96 === Abstract
Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) are both proinflammatory cytokines which trigger inflammatory chemokines secretion to control cell recruitment to sites of infection and inflammation. Macrophage inflammatory protein-1β (MIP-1β, chemokine cc motif ligand 4, CCL4) belongs to cc chemokine superfamily and is involved in chronic hepatitis. IL-1β binds to an interleukin-1 receptor 1 (IL-1R1) and TNF-α binds to a tumor necrosis factor receptor 1 (TNFR1) which both trigger intracellular mitogen-activated protein kinase (MAP kinase, MAPK) and nuclear factor-kappa B (NF-κB) signaling transduction, then caused to inflammatory response.
Helioxanthin (HE-145) was identified from the heartwood of Taiwania crytomerioides Hayata. In our previous study, it has been found that HE-145 inhibits IL-1β-induced MIP-1β expression through the block of JNK (c-Jun N-terminal kinase) signaling pathway in hepatoma cell line Huh7. In the preliminary study, I found that HE-145 also inhibited TNF-α-induced MIP-1β expression in hepatoma Huh7 cells. This study, I intended to investigate the inhibition mechanism of TNF-α-induced MIP-1β expression by HE-145. Quantitative-PCR analysis of the MAPK inhibitors revealed that TNF-α-induced MIP-1β expression through activating JNK signaling pathway. Results showed that HE-145 suppressed TNF-α-induced phosphorylation of JNK1/2 and c-Jun protein level using Western blot. HE-145 suppressed TNF-α-induced MIP-1β promoter activity using a promoter assay.
In addition, HE-145 derivatives of HE-145-8 and HE-145-12 inhibited TNF-α-induced MIP-1β expression using quantitative-PCR analysis. HE-145-8 and HE-145-12 inhibited TNF-α-induced MIP-1β expression through JNK signaling pathway using Western blot. HE-145-8 suppressed TNF-α-induced phosphorylation of JNK1/2 and c-Jun. However, HE-145-12 suppressed c-Jun at the protein level only.
In conclusion, HE-145 and its similar structural analogs can suppress both IL-1β-induced and TNF-α-induced inflammatory responses through JNK signaling pathway. They are potential candidates for drug development to suppress JNK signaling pathway. The mechanism of action of suppression of TNF-α-induced MIP-1β expression by HE-145 still needs further investigation.
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