Identification of downstream genes up-regulated by the tumor necrosis factor family member TALL-1.

TALL-1 is a member of the tumor necrosis factor family that binds to BCMA, TACI, and BAFF-R, three receptors mostly expressed by mature B lymphocytes. Previous studies have shown that the TALL-1 signaling is critically involved in B cell proliferation, maturation, and progression of lupus-like, autoimmune diseases. In this report, we performed cDNA subtractive hybridization experiments to identify downstream genes up-regulated by TALL-1. These experiments indicated that 10 genes, including interleukin (IL)-10, lymphocyte activation gene-1 (LAG-1), GCP-2, PBEF, ferritin, PIM-2, TFG, CD27 ligand, DUSP5, and archain, were up-regulated at the mRNA level by TALL-1 stimulation in B lymphoma RPMI-8226 cells and/or primary B lymphocytes. We also demonstrated that TALL-1 activated transcription of IL-10 and LAG-1 in a nuclear factor-kappaB-dependent manner in reporter gene assays. Moreover, our findings indicated BAFF-R, but not TACI, could dramatically up-regulate IL-10 secretion by RPMI-8226 cells. The identification of TALL-1-up-regulated genes will help explain the mechanisms of TALL-1-triggered biological and pathological effects and to identify molecular targets for intervention of lupus-like autoimmune diseases.