B cell lymphoma 10 is essential for FcepsilonR-mediated degranulation and IL-6 production in mast cells

The adaptor protein B cell lymphoma 10 (Bcl10) plays an essential role in the functions of the AgRs in T and B cells. In this study, we report that Bcl10 also plays an important role in mast cells. Bcl10 is expressed in mast cells. Although Bcl10-deficient mast cells undergo normal development, we demonstrate that Bcl10 is essential for specific functions of FcepsilonR. Although Bcl10-deficient mast cells have normal de novo synthesis and release of the lipid mediator arachidonic acid, the mutant cells possess impaired FcepsilonR-mediated degranulation, indicated by decreased serotonin release, and impaired cytokine production, measured by release of IL-6. In addition, Bcl10-deficient mice display impaired IgE-mediated passive cutaneous anaphylaxis. Moreover, although Bcl10-deficient mast cells have normal FcepsilonR-mediated Ca(2+) flux, activation of PI3K, and activation of the three types of MAPKs (ERKs, JNK, and p38), the mutant cells have markedly diminished FcepsilonR-mediated activation of NF-kappaB and decreased activation of AP-1. Thus, Bcl10 is essential for FcepsilonR-induced activation of AP-1, NF-kappaB, degranulation, and cytokine production in mast cells.     

Targeting the Wilms tumor antigen 1 by TCR gene transfer: TCR variants improve tetramer binding but not the function of gene modified human T cells

We have previously described the functional activity of a human TCR specific for an HLA-A2-presented peptide derived from the Wilms tumor Ag 1 (WT1). Recent studies showed that the expression and function of human TCR was improved by the introduction of an additional disulfide bond between the alpha- and beta-chains or by the exchange of the human constant region for murine sequences. In this study, we analyzed the functional activity of WT1-TCR variants expressed in Jurkat cells and in primary T cells. The introduction of cysteine residues or murine constant sequences into the WT1-TCR did not result in a global reduction of mispairing with wild-type TCR chains. Instead, the level of mispairing was affected by the variable region sequences of the wild-type TCR chains. The analysis of freshly transduced peripheral blood T cells showed that the transfer of modified TCR constructs generated a higher frequency of Ag-responsive T cells than the transfer of the wild-type TCR. After several rounds of peptide stimulation this difference was no longer observed, as all transduced T cell populations accumulated approximately 90% of Ag-responsive T cells. Although the Ag-responsive T cells expressing the modified TCR bound the HLA-A2/WT1 tetramer more efficiently than T cells expressing the wild-type TCR, this did not improve the avidity of transduced T cells nor did it result in a measurable enhancement in IFN-gamma production and cytotoxic activity. This indicated that the enhanced tetramer binding of modified WT1-TCR variants was not associated with improved WT1-specific T cell function.     

Therapeutic effect of anthracene-based anticancer agent ethonafide in an animal model of multiple sclerosis

The side effects of cancer chemotherapeutic agents such as mitoxantrone (MIT) in multiple sclerosis (MS) patients justify the search for less toxic drugs. Ethonafide is an anthracene-based antineoplastic drug similar to MIT. With reference to MIT, we examined the effect of ethonafide on experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice, an animal model of human MS. We demonstrated that ethonafide is effective in preventing development of EAE as well as in ameliorating the severity of EAE when disease is ongoing. In relatively higher dosages, the effects of ethonafide and MIT on EAE were identical, whereas in lower dosages, MIT seemed more effective. Therapeutic effects of ethonafide were associated with the initial reduction in cellular counts of CD3(+), CD4(+), CD8(+), B220(+), CD11b(+), NK cells, and NKT cells, followed by recovery of these cells from the bone marrow. Interestingly, the recovered autoreactive T cells in ethonafide-treated animals have reduced capacity to expand and produce cytokines in response to myelin Ag stimulation. Furthermore, CD4(+)CD25(+) regulatory T cells were relatively resistant to depletion and/or recovered faster than T effector cells. The ability of regulatory T cells to resist depletion and replenish quickly during cell ablation therapy may provide an opportunity to reprogram the immune system. Moreover, we provided evidences that ethonafide has less cardiac toxicity compared with MIT. The effectiveness and the low cardiotoxicity of ethonafide might make it a promising immunosuppressive agent for clinical use in treating MS patients.     

Promotion of Fas-mediated apoptosis in Type II cells by high doses of hepatocyte growth factor bypasses the mitochondrial requirement

The death receptor pathway is coupled to the mitochondria apoptosis pathway. However, mitochondrial participation, which is stimulated by Bid but suppressed by Bcl-2/Bcl-x(L), is required in certain cells (Type II), but not in others (Type I). While these differences were originally characterized in the lymphoid cell lines, the typical Type II cells are represented by hepatocytes in vivo. The molecular mechanisms that distinguish Type II from Type I cells and the regulation are not fully understood. Fas can be sequestered by the HGF receptor c-Met and high doses of HGF can promote cell death by freeing Fas from c-Met complex. We thus reasoned that treatment of the Type II cells with high doses of HGF could enhance Fas-mediated apoptosis and spare the mitochondria amplification. Indeed, such treatment led to increased apoptosis in Type II lymphoid cells, which could not be blocked by Bcl-x(L). Moreover, significant hepatocyte apoptosis was induced by this scheme in the absence of Bid with increased dissociation of Fas from c-Met. These findings indicate that high doses of HGF could be used to promote apoptosis in Type II cells bypassing the requirement for mitochondria activation.     

Changes in levels of juvenile hormone and molting hormone in larvae and adult females of Chilo suppressalis (Lepidoptera: Pyralidae) after imidacloprid applications to rice

Insect hormones regulate growth and development and fecundity of insects. The current study investigated changes in juvenile hormone (JH) and molting hormone (MH) levels in fourth instars and adult females of Chilo suppressalis (Walker) (Lepidoptera: Pyralidae) after imidacloprid application to rice, Oryza sativa L. The results showed that JH level in fourth instars that developed feeding on Fengyouxiangzhan rice plants sprayed with 15, 30, and 60 ppm imidacloprid was significantly higher than that of larvae that developed on control plants, increasing by 5.04, 6.39, and 4.89 times, respectively. The relationships between JH level and imidacloprid concentrations showed a significant negative correlation. In contrast, molting hormone (MH) level in larvae fed on control plants was significantly higher than that on treated plants. JH:MH values in fourth instars developed from larvae feeding on rice plants treated with 15, 30, 60, 80, and 100 ppm imidacloprid increased by 49.17, 39.43, 13.48, 15.80, and 0.2 times, respectively, compared with control. JH and JH:MH ratio in larvae fed on Wujing 15 plants treated with imidacloprid were significantly lower than those fed on Fengyouxiangzhan under the same treatments. JH level in adult females that developed from larvae feeding on rice plants sprayed with imidacloprid significantly decreased with increase in imidacloprid concentration, but it increased compared with control. JH level in adult females was associated with times of imidacloprid application. JH level in adult females developed from larvae feeding on rice plants after double spray with 30 ppm imidacloprid was significantly higher than control, increasing by 61.6 and 116.5%, respectively, compared with a single spray and the control. Moreover, hormone levels in the larvae were related to the application method of imidacloprid. JH level in fourth instars after root application and topical application of imidacloprid was significantly lower than in control. Thus, the dynamics of JH and MH in insects after insecticide applications are an extremely interesting problem, because hormones are related to insect growth and development.     

Production of authentic SARS-CoV M(pro) with enhanced activity: application as a novel tag-cleavage endopeptidase for protein overproduction

The viral proteases have proven to be the most selective and useful for removing the fusion tags in fusion protein expression systems. As a key enzyme in the viral life-cycle, the main protease (M(pro)) is most attractive for drug design targeting the SARS coronavirus (SARS-CoV), the etiological agent responsible for the outbreak of severe acute respiratory syndrome (SARS) in 2003. In this study, SARS-CoV M(pro) was used to specifically remove the GST tag in a new fusion protein expression system. We report a new method to produce wild-type (WT) SARS-CoV M(pro) with authentic N and C termini, and compare the activity of WT protease with those of three different types of SARS-CoV M(pro) with additional residues at the N or C terminus. Our results show that additional residues at the N terminus, but not at the C terminus, of M(pro) are detrimental to enzyme activity. To explain this, the crystal structures of WT SARS-CoV M(pro) and its complex with a Michael acceptor inhibitor were determined to 1.6 Angstroms and 1.95 Angstroms resolution respectively. These crystal structures reveal that the first residue of this protease is important for sustaining the substrate-binding pocket and inhibitor binding. This study suggests that SARS-CoV M(pro) could serve as a new tag-cleavage endopeptidase for protein overproduction, and the WT SARS-CoV M(pro) is more appropriate for mechanistic characterization and inhibitor design.     

Mutations in HOXD13 underlie syndactyly type V and a novel brachydactyly-syndactyly syndrome

HOXD13, the homeobox-containing gene located at the most 5' end of the HOXD cluster, plays a critical role in limb development. It has been shown that mutations in human HOXD13 can give rise to limb malformations, with variable expressivity and a wide spectrum of clinical manifestations. Polyalanine expansions in HOXD13 cause synpolydactyly, whereas amino acid substitutions in the homeodomain are associated with brachydactyly types D and E. We describe two large Han Chinese families with different limb malformations, one with syndactyly type V and the other with limb features overlapping brachydactyly types A4, D, and E and mild syndactyly of toes 2 and 3. Two-point linkage analysis showed LOD scores >3 (theta =0) for markers within and/or flanking the HOXD13 locus in both families. In the family with syndactyly type V, we identified a missense mutation in the HOXD13 homeodomain, c.950A-->G (p.Q317R), which leads to substitution of the highly conserved glutamine that is important for DNA-binding specificity and affinity. In the family with complex brachydactyly and syndactyly, we detected a deletion of 21 bp in the imperfect GCN (where N denotes A, C, G, or T) triplet-containing exon 1 of HOXD13, which results in a polyalanine contraction of seven residues. Moreover, we found that the mutant HOXD13 with the p.Q317R substitution was unable to transactivate the human EPHA7 promoter. Molecular modeling data supported these experimental results. The calculated interactions energies were in agreement with the measured changes of the activity. Our data established the link between HOXD13 and two additional limb phenotypes--syndactyly type V and brachydactyly type A4--and demonstrated that a polyalanine contraction in HOXD13, most likely, led to other digital anomalies but not to synpolydactyly. We suggest the term "HOXD13 limb morphopathies" for the spectrum of limb disorders caused by HOXD13 mutations.