Effect of TACI Signaling on Humoral Immunity and Autoimmune Diseases

Figure 3

The biological activities of TACI. TACI inhibits B cell proliferation by promoting the sustained expression of Blimp-1. Blimp-1 induces cell cycle arrest in B cells, promoting the differentiation of B cells into plasma cells (1). TACI inhibits GC reactions and B cell proliferation by suppressing the expression of ICOSL on GC B cells (2). TACI upregulates the expression of cIAP in GC B cells. cIAP targets NIK for degradation by ubiquitylation, thereby inhibiting the BR3-mediated noncanonical NF-κB pathway (3). TACI and TLR4 signalling cooperate to trigger MZ B cells to apoptosis by induction of Fas and FasL (4). TACI competes with BR3 for BAFF, which also downregulates the BAFF concentration (5). TACI inhibits plasma cell apoptosis by downregulating BIM expression in plasma cells (6). TACI mediates CSR by binding to MyD88 (7).