文摘
Ix3ba;Bx3b1; serves as a central anchoring molecule in the sequestration of NF-x3ba;B transcription factor in the cytoplasm. Ubiquitination-mediated Ix3ba;Bx3b1; degradation immediately precedes and is required for NF-x3ba;B nuclear translocation and activation. However, the precise mechanism for the deubiquitination of Ix3ba;Bx3b1; is still not fully understood. Using a proteomic approach, we have identified Ubiquitin Specific Peptidase 11 (USP11) as an Ix3ba;Bx3b1; associated deubiquitinase. Overexpression of USP11 inhibits Ix3ba;Bx3b1; ubiquitination. Recombinant USP11 catalyzes deubiquitination of Ix3ba;Bx3b1; in vitro. Moreover, knockdown of USP11 expression enhances TNFx3b1;-induced Ix3ba;Bx3b1; ubiquitination and NF-x3ba;B activation. These data demonstrate that USP11 plays an important role in the downregulation of TNFx3b1;-mediated NF-x3ba;B activation through modulating Ix3ba;Bx3b1; stability. In addition, overexpression of a catalytically inactive USP11 mutant partially inhibits TNFx3b1;- and IKKx3b2;-induced NF-x3ba;B activation, suggesting that USP11 also exerts a non-catalytic function in its negative regulation of TNFx3b1;-mediated NF-x3ba;B activation. Thus, Ix3ba;Bx3b1; ubiquitination and deubiquitination processes function as a Yin–Yang regulatory mechanism on TNFx3b1;-induced NF-x3ba;B activation.