Crystal structure of the p38 alpha-MAPKAP kinase 2 heterodimer

The p38 signaling pathway is activated in response to cell stress and induces production of proinflammatory cytokines. P38alpha is phosphorylated and activated in response to cell stress by MKK3 and MKK6 and in turn phosphorylates a number of substrates, including MAPKAP kinase 2 (MK2). We have determined the crystal structure of the unphosphorylated p38alpha-MK2 heterodimer. The C-terminal regulatory domain of MK2 binds in the docking groove of p38alpha, and the ATP-binding sites of both kinases are at the heterodimer interface. The conformation suggests an extra mechanism in addition to the regulation of the p38alpha and MK2 phosphorylation states that prevents phosphorylation of substrates in the absence of cell stress. Addition of constitutively active MKK6-DD results in rapid phosphorylation of the p38alpha-MK2 heterodimer.     

BALB/c mice produce blister-causing antibodies upon immunization with a recombinant human desmoglein 3

Pemphigus vulgaris (PV) is an Ab-mediated autoimmune blistering disease of mucotaneous surfaces. Over 95% of the patients with PV express DR4 or DRw6, and the disease is characterized by the presence of autoantibodies directed against desmoglein 3 (Dsg 3), a protein expressed on keratinocytes. An appropriate animal model is required to understand immunoregulation and to address the role of immunogenetic components in the production of pathogenic Abs that are characteristic of PV. Therefore, we turned to the development of a mouse model. Four strains of female mice (BALB/c, DBA/1, SJL/J, and HRS/J) were screened for their ability to produce pathogenic anti-Dsg 3 Abs. We demonstrated that only BALB/c mice immunized with a full-length Dsg 3 can produce pathogenic Abs capable of causing acantholysis of human foreskin in culture and blistering in neonatal mice. This observation suggested that either H-2d or the BALB background contains the immunogenetic makeup necessary for the production of pathogenic anti-Dsg 3 Abs. No correlation was noted between a given isotype and the pathogenic potential of autoantibodies from different strains of mice. Similarly, the pattern of reactivity of Abs with a panel of 46 synthetic peptides that span the entire Dsg 3 failed to reveal any association between binding specificity and the pathogenic potential, and suggested that pathogenic Abs might recognize conformational epitopes. Moreover, our studies showed that the epitopes recognized by pathogenic Abs are contained within the extracellular Dsg 3.     

Abnormal cell cycle regulation in primary human uveal melanoma cultures

Uveal malignant melanoma is the most frequent primary intraocular tumor in adult humans. The cellular events leading to neoplasic transformation of normal uveal melanocytes are not well known when compared to other cancers. In this study, we investigated the role of G1 and G1/S regulatory proteins of the cell cycle in human uveal melanoma (UM) primary cell cultures, since these proteins are common targets in tumor development. Further, freshly established and characterized tumor cells are a better model for in vitro studies when compared to cell lines established long ago. Human primary cell cultures from eight different UM were established, as well as one primary culture from rhesus uveal normal melanocytes (UNM). Primary human UM cultures were characterized by a low establishment and growing rate. From four successful cultures, three showed a high expression of cyclin D1, cyclin E, p16NK4A, and p27KIP1 with no variations in cyclin A, cyclin-dependent kinase 2 (CDK2), and CDK4. Interestingly, in one of the cultured tumors, tumor suppressor protein retinoblastoma (Rb) did not bind E2F despite the fact that Rb was found in its hypophosphorylated form. No mutations in either RB1 or the Rb-binding pocket of E2F-1 were detected. Furthermore, we identified seven proteins co-immunoprecipitating with Rb in this tumor, including Lamin A/C and six proteins not previously reported to bind Rb: Hsc70, high mobility group protein 1 (HMG-1), hnRPN, glyceraldehyde 3 phosphate dehydrogenase (G3PDH), EF-1, and EF-2. Our results indicate that the overexpression of cyclins D1/E and CDKIs p16 and p27, together with a deregulation of the Rb/E2F pathway, may be implicated in the development of human UM.     

SAR and factor IXa crystal structure of a dual inhibitor of factors IXa and Xa

Modifications to the P4 moiety and pyrazole C3 substituent of factor Xa inhibitor SN-429 provided several new compounds, which are 5-10nM inhibitors of factor IXa. An X-ray crystal structure of one example complexed to factor IXa shows that these compounds adopt a similar binding mode to that previously observed with pyrazole inhibitors in the factor Xa active site both with regard to how the inhibitor binds and the position of Tyr99.     

Selective induction of dendritic cells using granulocyte macrophage-colony stimulating factor,but not fms-like tyrosine kinase receptor 3-ligand,activates thyroglobulin-specific CD4+/CD25+ T cells and suppresses experimental autoimmune thyroiditis

Fms-like tyrosine kinase receptor 3-ligand (Flt3-L) and GM-CSF cause expansion of different subsets of dendritic cells and skew the immune response toward predominantly Th1 and Th2 type, respectively. In the present study, we investigated their effects on experimental autoimmune thyroiditis in CBA/J mice. Relative to mouse thyroglobulin (mTg) immunized controls, mTg-immunized mice treated with Flt3-L showed more severe thyroiditis characterized by enhanced lymphocytic infiltration of the thyroid, and IFN-gamma and IL-2 production. In contrast, mice treated with GM-CSF, either before or after immunization with mTg, showed suppressed T cell response to mTg and failed to develop thyroiditis. Lymphocytes from these mice, upon activation with mTg in vitro, produced higher levels of IL-4 and IL-10. Additionally, GM-CSF-treated mice showed an increase in the frequency of CD4(+)/CD25(+) T cells, which suppressed the mTg-specific T cell response. Neutralization of IL-10, but not IL-4, or depletion of CD4(+)/CD25(+) cells resulted in increased mTg-specific in vitro T cell proliferation suggesting that IL-10 produced by the Ag-specific CD4(+)/CD25(+) regulatory T cells might be critical for disease suppression. These results indicate that skewing immune response toward Th2, through selective activation of dendritic cells using GM-CSF, may have therapeutic potential in Th1 dominant autoimmune diseases including Hashimoto's thyroiditis.     

Novel route for the resolution of both enantiomers of dropropizine by using oxime esters and supported lipases of Pseudomonas cepacia

Resolution of (R)- and (S)-dropropizine which is an antitussive and central sedative therapeutic agent in high optical and chemical yields was achieved by lipases of Pseudomonas cepacia supported on ceramic particles (lipase PS-C) and on diatomite (lipase PS-D) with oxime esters in organic solvents. The influence of several factors (lipase source, structural variations in oxime esters, the amount of lipase and its recyclability) on the enantioselectivity have been investigated. Different properties were used to describe the solvents, namely the hydrophobicity (quantified by log P) and the dielectic constant (epsilon). This enzymatic acylation using oxime esters was significant as only (S)-dropropizine and (R)-dropropizine monoacetate was obtained. (R)-Dropropizine monoacetate was chemically hydrolyzed to obtain (R)-dropropizine. The highest enantioselectivity was observed when O-acetyl benzophenone oxime was used. This enzymatic resolution provides a versatile method for getting the pure enantiomers of dropropizine by effectively optimizing the various reaction parameters.     

Identification of potent inhibitors of Helicoverpa armigera gut proteinases from winged bean seeds

Dry mature seeds of winged bean (Psophocarpus tetragonolobus L., DC.) (WB) contain several proteinase inhibitors. Two-dimensional gel analysis of WB seed protein followed by activity visualization using a gel-X-ray film contact print technique revealed at least 14 trypsin inhibitors (TIs) in the range of 28-6 kD. A total of seven inhibitors (WBTI-1 to 7) were purified by heat treatment and gel filtration followed by elution from preparative native gels. Based on their biochemical characterization such as molecular mass, pI, heat stability, and susceptibility to inactivation by reducing agents, WBTI-1 to 4 are Kunitz type inhibitors while WBTI-5 to 7 are classified as Bowman-Birk type serine proteinase inhibitors. Although Kunitz type TIs (20-24 kD) of WB have been reported, the smaller TIs that belong to the Bowman-Birk type have not been previously characterized. Seven major TIs isolated from WB seed were individually assessed for their potential to inhibit the gut proteinases (HGP) of Helicoverpa armigera, a pest of several economically important crops, which produces at least six major and several minor trypsin/chymotrypsin/elastase-like serine proteinases in the gut. WBTI-1 (28 kD) was identified as a potent inhibitor of HGP relative to trypsin and among the other WBTIs; it inhibited 94% of HGP activity while at the same concentration it inhibited only 22% of trypsin activity. WBTI-2 (24 kD) and WBTI-4 (20 kD) inhibited HGP activity greater than 85%. WBTI-3,-5,-6 and-7 showed limited inhibition of HGP as compared with trypsin. These results indicate that WBTIs have different binding potentials towards HGP although most of the HGP activity is trypsin-like. We also developed a simple and versatile method for identifying and purifying proteinase inhibitors after two-dimensional separation using the gel-X-ray film contact print technique.     

Testicular development and its relationship to semen production in Murrah buffalo bulls

The objectives of this study were to determine the relationship of age and body weight to testicular development and to establish norms for breeding soundness evaluations of Murrah buffalo bulls. Testicular measurements of 133 Murrah buffalo bulls of various ages were recorded with a caliper and a tape. Semen was collected twice a week for 5 weeks from groups of bulls which were 25-36 (n=17), 37-48 (n=16), 49-60 (n=14), of >60 (n=10) months of age. After examining volume, sperm concentration, and progressive motility semen was diluted in Tris-citric acid-egg yolk-fructose extender and frozen in 0.5 ml French straws. Testicular measurements of buffalo bulls were lower than those recorded for European breeds of cattle bulls. Nevertheless, like cattle bulls, scrotal circumference was highly correlated with other testicular measurements. Also, it had a significant positive relationship with semen volume and sperm concentration per ejaculate. Average sperm output per week in order of increasing age group was 15.3, 18.2, 19.8 and 23.6 x 10(9). Corresponding values for sperm output per week per gram of testis were 59.1, 45.8, 41.1, 36.2 x 10(6) indicating a reduction in spermatogenesis per unit of testis with advancing age. Compared to European breeds, daily sperm output in Murrah bulls was nearly 45% lower, presumably due to their nearly 40% lower scrotal circumference than Holstein bulls of the same age. These results indicate that in buffalo, as in cattle, scrotal circumference is a useful indicator of potential sperm output and may serve as an important criterion for selecting young bulls as AI sires.     

Chickpea Defensive Proteinase Inhibitors Can Be Inactivated by Podborer Gut Proteinases

Developing chickpea (Cicer arietinum L.) seeds 12 to 60 d after flowering (DAF) were analyzed for proteinase inhibitor (Pi) activity. In addition, the electrophoretic profiles of trypsin inhibitor (Ti) accumulation were determined using a gel-radiographic film-contact print method. There was a progressive increase in Pi activity throughout seed development, whereas the synthesis of other proteins was low from 12 to 36 DAF and increased from 36 to 60 DAF. Seven different Ti bands were present in seeds at 36 DAF, the time of maximum podborer (Helicoverpa armigera) attack. Chickpea Pis showed differential inhibitory activity against trypsin, chymotrypsin, H. armigera gut proteinases, and bacterial proteinase(s). In vitro proteolysis of chickpea Ti-1 with various proteinases generated Ti-5 as the major fragment, whereas Ti-6 and -7 were not produced. The amount of Pi activity increased severalfold when seeds were injured by H. armigera feeding. In vitro and in vivo proteolysis of the early- and late-stage-specific Tis indicated that the chickpea Pis were prone to proteolytic digestion by H. armigera gut proteinases. These data suggest that survival of H. armigera on chickpea may result from the production of inhibitor-insensitive proteinases and by secretion of proteinases that digest chickpea Pis.