4:20 PM - 4:30 PM
[O1-D-PM1-04] Functional analysis of deamination in p65, a subunit of NF-κB, in oral squamous cell carcinoma
Keywords:deamination of p65、NF-κB、Oral squamous cell carcinoma (OSCC)
Oral squamous cell carcinoma (OSCC) is the most common malignant tumor of the oral cavity, head and neck. In OSCC, NF-κB signaling pathway is frequently activated. Recently, two deamidation sites (N64 and N139 residues) in p65, a subunit of NF-κB, in several cancer cells, but their functions are not fully understood. Post-translational modification, including deamidation, plays an important role in the regulation of protein function. The short-term deamidation of certain proteins is reported to be necessary for cancer cells and microorganisms to escape from antigens. In the present study, we examine the function of the two deamidation residues in p65 by substituting to N64D and N139D. We tried to generate two types of antibodies, which recognize N64D and N139D, respectively, but we only got one type that recognized N139D. The embryonic fibroblasts prepared from p65-deficient mice were transfected with one of the expression plasmids that carried WT, N64D, N139D and both N64D and N139D (DD) in p65. Although N64D did not change the transcriptional activity of p65, N139D significantly decreased it in p65. Protein levels of WT, N64D and N139D were comparable, but only DD was remarkably low, suggesting that the DD substitutions decrease the transcriptional activity of p65 depend on the protein levels. Treatment with an autophagy inhibitor (Bafilomycin A1), but not with a proteasome inhibitor (MG132), kept the protein level of p65 DD comparable to that of WT. Taken together, it was suggested that p65 N139 regulates the transcriptional activity and protein levels of p65 through an autophagy mechanism