Project description:The transcription factor NF-κB is the master regulator of the immune response but also regulates gene expression to influences cell survival, proliferation and differentiation. Inducible site-specific phosphorylation of NF-κB is critical for its activity and appears to be important in gene specific transcriptional control. Promyelocytic Leukemia (PML) is a nuclear protein that forms sub-nuclear structures termed nuclear bodies associated with transcriptionally active genomic regions. We demonstrate that PML promotes NF-κB- induced transcriptional responses by promoting the phosphorylation of NF-κB p65 at key regulatory sites. Our findings demonstrate a critical role for PML in promoting NF-κB transcriptional activity through signal induced post-translational modifications.
Project description:Pseudogenes are thought to be inactive gene sequences, but recent evidence of extensive pseudogene transcription raised the question of potential function. Here we discover and characterize the sets of lncRNAs induced by inflammatory signaling via TNFα. TNFα regulates hundreds of lncRNAs, including 54 pseudogene lncRNAs, several of which show exquisitely selective expression in response to specific cytokines and microbial components in a NF-κB-dependent manner. Lethe, a pseudogene lncRNA, is selectively induced by proinflammatory cytokines via NF-κB or glucocorticoid receptor agonist, and functions in negative feedback signaling to NF-κB. Lethe interacts with NF-κB subunit RelA to inhibit RelA DNA binding and target gene activation. Lethe level decreases with organismal age, a physiological state associated with increased NF-κB activity. These findings suggest that expression of pseudogenes lncRNAs are actively regulated and constitute functional regulators of inflammatory signaling. RNA profiles of wild type (WT) MEFs treated with TNF-alpha were generated by deep sequencing using Illumina GAIIx. Examination of H3K4me3 histome modification in MEF.
Project description:The transcription factor NF-κB is considered the master regulator of the immune response but also acts broadly to regulate gene expression that influences cell survival, proliferation and differentiation. Post-translational modification of NF-κB, phosphorylation in particular, is essential for the transactivation activity of NF-κB. Emerging evidence suggests that the regulation of NF-κB in the nucleus is critical in controlling gene expression. Promyelocytic Leukemia (PML) is a nuclear protein that forms nuclear bodies (PML NBs), sub-nuclear structures that are associated with transcriptionally active genomic regions that have been implicated in multiple processes such as apoptosis, senescence and anti-viral responses. Chromosomal translocations leading to the expression of a PML-retinoic acid receptor-α (PML-RARα) fusion protein are causative for acute promyelocytic leukemia (APL) characterised by a differentiation block at the promyelocytic state of myeloid development. Here we demonstrate that PML is required for phosphorylation of NF-κB p65 and that PML is essential for NF-κB- induced transcriptional responses. Our analysis of available transcriptional profiles of all-trans retinoic acid treated acute promyelocytic leukemia (APL) cells identifies a NF-κB transcriptional programme suppressed by PML-RARα. We further demonstrate that PML-RARα inhibits NF-κB phosphorylation and transcriptional activity. Our findings demonstrate a critical role for PML in promoting NF-κB transcriptional activity which may contribute to APL initiation and maintenance. WT and PML-/- MEFs were analysed for gene expression analysis. Total of 12 samples, inlcluding triplicates were utilized. WT MEFs and PML-/- were stimulated with TNFα for three hours and analysed for gene expresison using unstimulated WT MEFs as control.
Project description:By binding to specific DNA elements, known collectively as “κB sites”, contained within the promoters/enhancers of target genes, NF-κB regulates gene expression. We found that the identity of the central base pair (bp) of κB sites profoundly impacts the transcriptional activity of NF-κB dimers. RelA dimers prefer an A/T bp at this position for optimum transcriptional activation (A/T-centric) and discriminate against G/C-centric κB sites. The p52 homodimer, in contrast, activates transcription from G/C-centric κB sites in complex with Bcl3 but represses transcription from the A/T-centric sites. The p52:Bcl3 complex binds to these two classes of κB sites in distinct modes permitting recruitment of coactivator, corepressor, or both coactivator and corepressor complexes in promoters containing G/C, A/T or both G/C and A/T-centric sites. Therefore, through sensing of bp differences within κB sites, NF-κB dimers modulate biological programs by activating, repressing and altering expression of effector genes. Total RNA extracted from bone marrow derived macrophages (BMDMs) with Bcl3 siRNA knockdown or mouse scramble siRNA knockdown were subjected to LPS stimulation.
Project description:Effective host defense against infection relies on the tight coordination of immune activation, metabolic adaptation, and redox control, yet how these processes are integrated remains incompletely understood. Here, we identify dipeptidyl peptidase 3 (Dpp3) as a negative regulator of antimicrobial immunity. Dpp3-/- mice exhibit enhanced resistance to Klebsiella pneumoniae infection, with reduced bacterial burden, preserved tissue integrity, and attenuated systemic inflammation. This response is associated with increased phagocytic activity, expansion of germinal centres and plasma cells, and elevated interferon-γ production by T cells. Mechanistically, Dpp3 deficiency leads to reduced Nrf2 protein levels upon stimulation, resulting in heightened ROS accumulation and amplified NF-κB signaling. Integrated metabolomic and transcriptomic analyses of Dpp3-/- immune cells reveal mitochondrial dysfunction and a shift toward biosynthetic and antioxidant-supportive metabolic programs. Collectively, our findings identify Dpp3 as a molecular brake on host defense and uncover a regulatory axis linking redox balance, immunometabolism, and inflammation during infection.
Project description:Transcription factor NF-κB regulates cellular responses to environmental cues. For many stimuli NF-κB resides only transiently in the nucleus. Consequently, time-dependent transcriptional outputs are a fundamental feature of NF-κB activation. Here we identify mechanisms that direct kinetic patterns of NF-κB-dependent gene expression and transcriptional outcomes in response to a transient NF-κB-inducing stimulus in B cells. By combining RELA binding, RNA polymerase II (Pol II) recruitment, and perturbation of NF-κB activation, we demonstrate that kinetic differences amongst early- and late-activated RELA target genes can be understood based on chromatin configuration prior to cell activation and RELA-dependent priming, respectively. Additionally, we identified genes that were repressed by RELA activation and others that responded to RELA-activated transcription factors. Cumulatively, our studies define an NF-κB-responsive inducible gene cascade in activated B cells.