P54/nrb prompts rheumatoid arthritis progression mainly by transcriptionally activating NF-κB signaling

In various tumors, aberrant expression of P54/nrb has been identified. However, the expression pattern and specific role of P54/nrb in rheumatoid arthritis (RA) has never been explored. Here, we first demonstrated that the expression of P54/nrb was markedly enhanced in the synovial tissues of RA patients. Functional study showed that P54/nrb could enhance the levels of inflammatory factors, including IL-1, IL-2, IL-6, IL-8 and TNFα. More importantly, we first found that overexpression of P54/nrb can induce the protein levels of P65, an important subunit of NF-κB. In contrast, knockdown of P54/nrb by RNAi significantly decreased the expression of NF-κB. Luciferase reporter assay and CHIP assay showed that P54/nrb could transcriptionally activate the expression of NF-κB, thereby enhancing pro-inflammatory responses. In summary, the expression of p54 was markedly increased in the synovial tissues of RA patients. Further study demonstrated that p54 could transcriptionally activate the expression of p65, an important NF-κB subunit, thereby enhancing the pro-inflammatory response.