Putative role of β‐arrestin 2 in regulating TNF signalling to NFκB pathway: Molecular and cell biology/neuroinflammation.

Background: Neuroinflammation is one of the features observed in neurodegenerative diseases, and inflammatory cytokines and chemokines are two of the important players in the neuroinflammatory responses. β‐arrestin 2 has also been reported to play a crucial role in regulating cytokines and chemokines release as the loss of β‐arrestin 2 leads to an increase in the sepsis‐induced inflammation. However, the role of β‐arrestin 2 in regulating the TNF mediated cytokines and chemokines production is poorly understood. Method: Stable β‐arrestin 2 knockdown (KD) and negative control (NC) SH‐SY5Y clone cells were used for this study. Subcellular fractionation was used to investigate the cell surface TNF‐R1, and co‐immunoprecipitation (co‐IP) was performed to determine for the possible interaction between TNF‐R1 and β‐arrestin 2. Immunoblotting was used to investigate P65 phosphorylation status. Lastly, cytokines and chemokines mRNA expressions were quantified using Real Time‐PCR after TNF treatment. Result: Subcellular fractionation showed significantly more TNF‐R1 remained on the cell membrane fraction of KD compared to NC. Using NC cells, co‐IP showed the possible interaction between TNF‐R1 and β‐arrestin 2. KD also demonstrated significant increase in P65 phosphorylation compared to NC, along with significantly higher mRNA expressions of cytokines and chemokines. Conclusion: These results suggest that prolong TNF‐R1 on the membrane, possibly due to the lack of desensitization by β‐arrestin 2, may have led to an increase in the P65 phosphorylation, and resulting in a significant increase in the cytokines and chemokines mRNA expressions. Hence, our findings established the important role of β‐arrestin 2 in the TNF mediated NFκB pathway, and cytokines and chemokines production. [ABSTRACT FROM AUTHOR]