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IkappaB Kinase (IKK)alpha is required for activation of an alternative NF-kappaB signaling pathway based on processing of the NF-kappaB2/p100 precursor protein, which associates with RelB in the cytoplasm. This pathway, which activates RelB:p52 dimers, is required for induction of several chemokine genes needed for organization of secondary lymphoid organs.(More)
Radiation-induced apoptosis (RiA) is used therapeutically for tumor cell ablation as well as a tool to characterize hemopoietic cell lineages. We report that the peritoneal B-1 B cell subset is selectively resistant to RiA. Inherent radioresistance is not shared by splenic B-2 or B-1 cells. However, it is conferred upon B-2 cells by BCR crosslinking in the(More)
Non-coding microRNAs (miRs) are a vital component of post-transcriptional modulation of protein expression and, like coding mRNAs harbour oncogenic properties. However, the mechanisms governing miR expression and the identity of the affected transcripts remain poorly understood. Here we identify the inositol phosphatase SHIP1 as a bonafide target of the(More)
Proliferative expansion of pro-B cells is an IL-7-dependent process that allows for the rearrangement of H chain genes and the expression of the pre-B cell receptor (pre-BCR). Further B cell differentiation is dependent upon signals elicited through the pre-BCR, which are thought to be responsible for allelic exclusion, induced L chain gene rearrangement,(More)
Expression of B cell-activating factor (BAFF), a critical B cell survival factor, is elevated in autoimmune and lymphoproliferative disorders. Mice overproducing BAFF develop systemic lupus erythematosus (SLE)-like disease and exhibit B cell activation of classical and alternative NF-kappaB-signaling pathways. We used a genetic approach and found that both(More)
CD19 is rapidly phosphorylated upon B-cell antigen receptor (BCR) cross-linking, leading to the recruitment of downstream signaling intermediates. A prominent feature of CD19 signaling is the binding and activation of phosphoinositide 3-kinase (P13K), which accounts for the majority of PI3K activity induced by BCR ligation. Recent findings have implicated(More)
Loss of membrane-bound Ig results in the rapid onset of apoptosis in recirculating B cells. This observation implies that a competent B cell receptor (BCR) is not only required for Ag-dependent differentiation, but also for continued survival in the peripheral immune system. Expression of the B cell coreceptor, CD19, is likewise essential for key B cell(More)
Mice lacking activity of the kinase MEKK1 ('Map3k1(deltaKD)' mice) have defective activation of the kinase Jnk and increased production of T helper type 2 cytokines after T cell receptor ligation. Here we show that Map3k1(deltaKD) mice had defective germinal center formation and diminished production of antibodies recognizing thymus-dependent antigens.(More)
Although the B-cell antigen receptor (BCR) factors most prominently in the maintenance and differentiation of mature B cells, it is now appreciated that co-receptor molecules can positively or negatively modulate signals through the BCR. Co-receptors are functionally defined as modifiers of BCR engagement and signal transduction, and are distinct from other(More)
The contributions of IFN regulatory factor (IRF) 3/7 and the type I IFNs IFN-α/β to the innate host defense have been extensively investigated; however, their role in thymic development is less clear. In this study, we show that mice lacking the type I IFN receptor IFN-α/β receptor (IFNAR) or the downstream transcription factor STAT1 harbor a significant(More)