Membrane-associated serine protease matriptase is widely expressed by epithelial/carcinoma cells in which its proteolytic activity is tightly controlled by the Kunitz-type protease inhibitor, hepatocyte growth factor activator inhibitor (HAI-1). We demonstrate that, although matriptase is not expressed in lymphoid hyperplasia, roughly half of the non-Hodgkin B-cell lymphomas analyzed express significant amounts of matriptase. Furthermore, a significant proportion of these tumors express matriptase in the absence of HAI-1. Aggressive Burkitt lymphoma was more likely than indolent follicular lymphoma to express matriptase alone (86% versus 36%). In the absence of significant HAI-1 expression, the lymphoma cells activate and shed active matriptase when the cells are stimulated with mildly acidic buffer or the hypoxia-mimicking agent, CoCl2. The shed active matriptase can initiate pericellular proteolytic cascades by activating urokinase-type plasminogen activator on the cell surface of monocytes, and it can activate prohepatocyte growth factor. In addition, matriptase knockdown suppressed proliferation and colony-forming ability of neoplastic B cells in culture and growth as tumor xenografts in mice. Furthermore, exogenous expression of HAI-1 significantly suppressed proliferation of neoplastic B cells. These studies suggest that dysregulated pericellular proteolysis as a result of unregulated matriptase expression with limited HAI-1 may contribute to the pathological characteristics of several human B-cell lymphomas through modulation of the tumor microenvironment and enhanced tumor growth.

BackgroundDengue virus (DV) infection causes a spectrum of clinical diseases ranging from dengue fever to a life-threatening dengue hemorrhagic fever. Four distinct serotypes (DV1–4), which have similar genome sequences and envelope protein (E protein) antigenic properties, were divided. Among these 4 serotypes, DV1 usually causes predominant infections and fast diagnosis and effective treatments are urgently required to prevent further hospitalization and casualties.MethodsTo develop antibodies specifically targeting and neutralizing DV1, we immunized mice with UV-inactivated DV1 viral particles and recombinant DV1 E protein from residue 1 to 395 (E395), and then generated 12 anti-E monoclonal antibodies (mAbs) as the candidates for a series of characterized assays such as ELISA, dot blot, immunofluorescence assay, western blot, and foci forming analyses.ResultsAmong the mAbs, 10 out of 12 showed cross-reactivity to four DV serotypes as well as Japanese encephalitis virus (JEV) in different cross-reactivity patterns. Two particular mAbs, DV1-E1 and DV1-E2, exhibited strong binding specificity and neutralizing activity against DV1 and showed no cross-reactivity to DV2, DV3, DV4 or JEV-infected cells as characterized by ELISA, dot blot, immunofluorescence assay, western blot, and foci forming analyses. Using peptide coated indirect ELISA, we localized the neutralizing determinants of the strongly inhibitory mAbs to a sequence-unique epitope on the later-ridge of domain III of the DV1 E protein, centered near residues T346 and D360 (346TQNGRLITANPIVTD360). Interestingly, the amino acid sequence of the epitope region is highly conserved among different genotypes of DV1 but diverse from DV2, DV3, DV4 serotypes and other flaviviruses.ConclusionsOur results showed two selected mAbs DV1-E1 and DV1-E2 can specifically target and significantly neutralize DV1. With further research these two mAbs might be applied in the development of DV1 specific serologic diagnosis and used as a feasible treatment option for DV1 infection. The identification of DV1 mAbs epitope with key residues can also provide vital information for vaccine design.

Enzymatic glycosylation of sterols/steroids with glycosyltransferase HP0421 shows protein plasticity on generation of configurationally rare steryl-α-glucosides. Investigation of trans-androsteronyl-α-glucoside on tamoxifen-treated MCF-7 breast cancer cells shows dose-dependent depression of cell viability and enhanced drug effectiveness, illustrating a new avenue for the production of novel steryl-α-glucosides with useful biological activities.

It is important to develop viable technologies for efficient hydrogen (H2) production and carbon dioxide (CO2) conversion to realize the future supply of clean energy and reduction of global CO2 concentration. Herein, we report a series of carbamate‐substituted ruthenium‐dithiolate complexes 1–3, [Rux(CO)y(μ‐SCH(NCO2(C(CH3)3))CH2CH2S)] (x=2, 3, 6 and y=6, 9, 20), which can effectively catalyze the reversible formic acid‐carbon dioxide (FA‐CO2/H2) cycle that can be used to convert CO2 and produce H2. Complex 2 effectively dehydrogenates FA to produce H2 with an unprecedented turnover frequency (TOF) of 1.15×106 h−1 under conditions of sunlight irradiation. Under conditions of high temperature and pressure, complex 3 hydrogenates CO2 to FA with a high initial TOF of 1.02×106 h−1, resulting in an efficient FA‐CO2/H2 cycle. These results can potentially help provide the platform for the development of technologies that can be used in future to produce clean energy and control environmental threats.

We report here that pregnenolonyl-α-glucoside (2) exhibits significant dose-dependent cytotoxicity against HT29, AGS, and ES-2 cells. The biochemical characterization results indicates the putative mechanism of 2 on the catalytic site of CYP17A1.

Oligomerization of protein into specific quaternary structures plays important biological functions, including regulation of gene expression, enzymes activity, and cell–cell interactions. Here, we report the determination of two crystal structures of the Grimontia hollisae (formally described as Vibrio hollisae ) thermostable direct hemolysin (Gh–TDH), a pore-forming toxin. The toxin crystalized in the same space group of P 2 1 2 1 2, but with two different crystal packing patterns, each revealing three consistent tetrameric oligomerization forms called Oligomer–I, –II, and –III. A central pore with comparable depth of ~50 Å but differing in shape and size was observed in all determined toxin tetrameric oligomers. A common motif of a toxin dimer was found in all determined structures, suggesting a plausible minimum functional unit within the tetrameric structure in cell membrane binding and possible hemolytic activity. Our results show that bacterial toxins may form a single or highly symmetric oligomerization state when exerting their biological functions. The dynamic nature of multiple symmetric oligomers formed upon release of the toxin may open a niche for bacteria survival in harsh living environments.