Interleukin-1␤ (IL-1␤ IntroductionInterleukin-1␤ (IL-1␤) plays an important role in infection and inflammation. 1 The generation of IL-1␤ is divided into 2 stages. In the first stage, inflammatory stimuli activate nuclear factor-B (NF-B) to promote the synthesis of pro-IL-1␤. In the second stage, pro-IL-1␤ protein is cleaved by caspase-1 to generate mature p17 IL-1␤ protein. The activation of caspase-1 is dependent on the formation of large multiprotein complexes inflammasomes in macrophages and monocytes. [2][3][4][5][6] Assembly of inflammasomes is stimulated by infection, inflammation, or danger signals. The NACHT domain-, leucine-rich repeat-, and pyrin domaincontaining protein 3 (NLRP3, also known as NALP3 or cryopyrin) inflammasome responds to a large array of stimulation, including microbial products, toxins, adenosine triphosphate (ATP), crystalline, aggregated particles. [7][8][9][10][11][12][13][14] The NLRP3 protein consists of an N-terminal pyrin domain for protein-protein interaction, a central NACHT domain for nucleotide binding and self-oligomerization, and C-terminal leucine-rich repeat motifs for ligand sensing. Mutation of the NLRP3 gene is associated with several autoinflammatory disorders, and NLRP3 is also linked to gout and diabetes. 5,15 Two signals are required for formation of NLRP3 inflammasome. NF-B-containing inflammatory signals activate NLRP3 expression. 16 A second inflammatory signal then stimulates the assembly of the NLRP3 inflammasome, through the binding of NLRP3 to apoptosis-associated speck-like protein containing a CARD domain (ASC) and recruitment of procaspase-1 molecule. Reactive oxygen species 10,13,17 and lysosomal protease cathepsin B 12,13 are potential activators of the NLRP3 inflammasome assembly. However, how inflammatory stimuli promote the formation of the NLRP3 inflammasome remains largely unclear. [2][3][4][5][6] In contrast, NLRP1 inflammasome has been successfully reconstituted in vitro with the recombinant proteins. 18 Part of the difficulties is the result of the spontaneous formation of inflammasome in vitro on cell membrane damage during the preparation of cell lysates. 19 Death-associated protein kinase (DAP-kinase, DAPk, or DAPK) is calcium/calmodulin-regulated Ser/Thr kinase that acts as a tumor suppressor. 20,21 Diminished DAPK expression is found in various types of cancer, including B lymphoma and chronic lymphocytic leukemia. 22-24 DAPK also mediates pathologic damages, such as N-methyl-D-aspartate receptor-triggered neuronal cell death. 25 DAPK is organized into multiple domains: an N-terminal kinase domain, followed by a calcium/calmodulin regulatory fragment, ankyrin repeats, a cytoskeleton binding region, and a C-terminal death domain. The multifunctional domains of DAPK are linked to diverse activities. 20,21 [26][27][28][29] and specific inhibition of T cell receptor-induced activation by DAPK. 30 DAPK is also part of a negative-feedback module in regulating the expression of inflammatory genes. 31 Recent studies reveal an intriguing interpl...

Key Points PML selectively activates NLRP3 inflammasome. Targeting to PML could be used to attenuate NLRP3 inflammasome–associated pathogenesis.

QC (glutaminyl cyclase) catalyses the formation of N-terminal pGlu (pyroglutamate) in peptides and proteins. pGlu formation in chemoattractants may participate in the regulation of macrophage activation and migration. However, a clear molecular mechanism for the regulation is lacking. The present study examines the role of QC-mediated pGlu formation on MCPs (monocyte chemoattractant proteins) in inflammation. We demonstrated in vitro the pGlu formation on MCPs by QC using MS. A potent QC inhibitor, PBD150, significantly reduced the N-terminal uncyclized-MCP-stimulated monocyte migration, whereas pGlu-containing MCP-induced cell migration was unaffected. QC small interfering RNA revealed a similar inhibitory effect. Lastly, we demonstrated that inhibiting QC can attenuate cell migration by lipopolysaccharide. These results strongly suggest that QC-catalysed N-terminal pGlu formation of MCPs is required for monocyte migration and provide new insights into the role of QC in the inflammation process. Our results also suggest that QC could be a drug target for some inflammatory disorders.

Ezrin links cortical actin filaments with the cell membrane, and has a critical role in many membrane-initiated events. Fas is directly associated with ezrin, but conflicting results have been reported for the involvement of ezrin in Fas-induced cell death. In this study we show that ezrin was associated with Fas in T cells before stimulation and was released shortly after Fas ligand (FasL) engagement. The knockdown of ezrin moderately increased Fastriggered or tumor necrosis factor-related apoptosisinducing ligand (TRAIL)-triggered cell death in normal T lymphocytes and in H9 cells, but had no effect on death receptor-induced apoptosis in type II cells, such as Jurkat and CEM. Expression of a dominant-negative form of ezrin also led to an increased Fas-induced apoptosis in H9 cells. Ezrin deficiency did not affect the internalization of Fas after Fas ligation. Instead, an enhanced formation of death-inducing signaling complex (DISC) was observed in H9 cells with ezrin knockdown, leading to accelerated caspase-8 activation. Together, our results suggest that ezrin has a negative role in the recruitment of Fas into signaling complexes in type I T cells. Loss of ezrin likely removes the constraint imposed by ezrin and facilitates the assembly of death receptor complex in T cells.