Proinflammatory Effects of Ubiquitin-Specific Protease 5 (USP5) in Rheumatoid Arthritis Fibroblast-Like Synoviocytes

Figure 6

USP5 removed K48-linked polyubiquitination conjugate from TRAF6. (a) RA-FLS cells were infected with increasing titer of lentivirus that contains USP5 expression plasmid, followed by the stimulation by IL-1β (10 ng/ml) for 9 hours. The expression of TRAF6 was examined. (b) RA-FLS cells were infected with lentivirus that contain negative control plasmid or USP5 shRNA plasmid, followed by the stimulation by IL-1β (10 ng/ml) for 9 hours. The expression of TRAF6 was examined. (c) Protein levels of USP5 and TRAF6 in FLS from 8 RA patients. (d) The correlation of the relative USP5 level and relative TRAF6 level in (c) was calculated by using GraphPad Prism Software. (e) Lysates from RA-FLS cells transiently cotransfected with Myc-USP5, Flag-TRAF6, or vector control and HA-Ub (WT), HA-Ub (K48), or HA-Ub (K63) plasmids were subjected to immunoprecipitation with anti-Flag antibody followed by Western blot analysis with anti-HA antibody.

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