Context: Wutou decoction (WTD) is a Chinese herbal formula alleviating rheumatoid arthritis (RA). SHC adaptor protein 1 (SHC1) regulates apoptosis, inflammation, and the production of reactive oxygen species (ROS). The LOC101928120 gene is located near the SHC1 gene. Bioinformatics analysis showed that the long non-coding RNA LOC101928120 binds to histone deacetylase HDAC1 that might regulate SHC1 expression. The LOC101928120 gene might be targeted by the transcriptional factor Aryl hydrocarbon receptor (Ahr).
Objective: This study determines the involvement of the Ahr/LOC101928120/SHC1 pathway in WTD alleviation of RA.
Materials and methods: Wistar rats were injected with complete Freund's adjuvant in the hind footpad to construe the RA model. WTD (9.8 g/kg/day) was administered intragastrically for 15 days. The CHON-001 chondrocyte cells were treated with IL-1β (10 ng/mL) alone or in combination with WTD (1 μg/mL). A RNA pull-down assay was performed to determine the interaction between LOC101928120 and HDAC1. Ahr targeting the LOC101928120 gene was detected using luciferase reporter and chromatin immunoprecipitation assays.
Results: WTD alleviated the swelling of the hind paw in rats with RA and suppressed the chondrocyte apoptosis and ROS production caused by IL-1β. WTD decreased SHC1 but increased LOC101928120 in IL-1β-treated chondrocytes. SHC1 knockdown and LOC101928120 overexpression also showed the protection. However, LOC101928120 knockdown attenuated the protective effects of WTD. WTD stimulated Ahr, which promoted LOC101928120 transcription. LOC101928120 recruited HDAC1 to the promoter region of the SHC1 gene, thereby decreasing SHC1.
Discussion and conclusion: This study revealed a new mechanism by which WTD alleviates RA by modulating the Ahr/LOC101928120/SHC1 pathway.
Keywords: HDAC1; RNA pull-down; ROS production; histone deacetylation; transcription factor.