Bioinformatic mining of EST-SSR loci in the Pacific oyster, Crassostrea gigas

A set of expressed sequence tag-simple sequence repeat (EST-SSR) markers of the Pacific oyster, Crassostrea gigas, was developed through bioinformatic mining of the GenBank public database. As of June 30, 2007, a total of 5132 EST sequences from GenBank were downloaded and screened for di-, tri- and tetra-nucleotide repeats, with criteria set at a minimum of 5, 4 and 4 repeats for the three categories of SSRs respectively. Seventeen polymorphic microsatellite markers were characterized. Allele numbers ranged from 3 to 10, and the observed and expected heterozygosity values varied from 0.125 to 0.770 and from 0.113 to 0.732 respectively. Eleven loci were at Hardy-Weinberg equilibrium (HWE); the other six loci showed significant departure from HWE (P < 0.01), suggesting possible presence of null alleles. Pairwise check of linkage disequilibrium (LD) indicated that 11 of 136 pairs of loci showed significant LD (P < 0.01), likely due to HWE present in single markers. Cross-species amplification was examined for five other Crassostrea species and reasonable results were obtained, promising usefulness of these markers in oyster genetics.

A randomized clinical study of surgery versus radiotherapy in the treatment of resectable esophageal cancer

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Background: To compare the treatment results between radical surgery and late-course accelerated hyperfractionation radiotherapy (LCAHFR) for patients with resectable thoracic segment esophageal cancer. Methods: From June 1998 to September 2002, 269 patients with resectable thoracic esophageal cancer were randomized into two groups. 135 were with surgery and 134 with late-course accelerated hyperfractionated (LCAF) radiotherapy. Chemotherapy only for clinical recurrence and salvage therapy. Results: The 1-, 3- and 5- year overall survival rate were 88.6%, 56.2% and 34.7% in the surgery group and 93.3%, 61.5% and 36.9% in the radiotherapy group. There was no statistical difference between the two groups (P =0.58). Median survival was 28.5 months and 30.5 months respectively. The 1-, 3-and 5-year progression-free survival rate was 73.3%, 39.7% and 20.6% in the surgery group and 75.9%, 43.7% and 23.1% in the radiotherapy group (P =0.65) . There was no difference between the two groups in survival rates including different location and length (P > 0.05). The incidence of failure by hematogenous metastasis and distant lymphatic metastasis in the radiotherapy group (16.6% and 13.3% respectively ) was lower than in the surgery group ( 25.3% and 20.3 % respectively ), there was no significance between them. The incidence of local failure in the radiotherapy and surgery group was 57.3% and 27.8% respectively (P = 0.001) The incidence of death by local reasons was higher than in the surgery group (P = 0.02 ). The incidence of death by distant metastasis was lower than in the surgery group (P = 0.02 ). Conclusion: The treatment results between radical surgery and LCAHFR with conformal radiotherapy for patients with resectable thoracic esophageal cancer were comparable.

No significant financial relationships to disclose.

Cooperation of BCR-ABL and AML1/MDS1/EVI1 in blocking myeloid differentiation and rapid induction of an acute myelogenous leukemia

The development of acute myelogenous leukemia (AML), which is characterized by a block of myeloid differentiation, is a multi-step process that involves several genetic abnormalities, but the molecular mechanisms by which these genetic alterations cooperate in leukemogenesis are poorly understood. The human chronic myelogenous leukemia (CML) is a model for multi-step leukemogenesis. BCR-ABL, a constitutively active tyrosine kinase, is a fusion protein generated by the t(9;22)(q34;q11) translocation found in the vast majority of CML patients. BCR-ABL efficiently induces a myeloproliferative disorder (MPD) in mice, but progression to CML blast phase requires additional mutations. The AML1/MDS1/EVI1 (AME) transcription factor fusion protein, is a product of the human t(3;21)(q26;q22) translocation found as a secondary mutation in some cases of CML during the blast phase. We have previously shown that AME can induce an AML in mice but with a greatly extended latency, suggesting a requirement for additional mutations. Here we demonstrate that AME alone does not block myeloid differentiation in vivo during the 4-month pre-leukemia stage, yet co-expression of BCR-ABL and AME in mice can block myeloid differentiation and rapidly induce an AML. Our results suggest that block of myeloid differentiation and induction of AML involves cooperation between mutations that dysregulate protein tyrosine kinase signaling and those that disrupt hematopoietic gene transcription.

[Nondestructive quantitative analysis of Paracetamoli powder pharmaceutical by artificial neural network and near-infrared spectroscopy]

The application of artificial neural network for pharmaceutical nondestructive quantitative analysis were investigated. Real data set from near infrared reflectance spectra of Paracetamoli powder pharmaceutical were used to build up artificial network to predict unknown samples. The parameters affecting network were discussed. A new network evaluation criterion, the degree of approximation, was employed. Owing to good nonlinear multivariate calibration nature of ANN, the predicted results was reliable.

The NH(2)-terminal coiled-coil domain and tyrosine 177 play important roles in induction of a myeloproliferative disease in mice by Bcr-Abl

Bcr-Abl, a fusion protein generated by t(9;22)(q34;q11) translocation, plays a critical role in the pathogenesis of chronic myelogenous leukemia (CML). It has been shown that Bcr-Abl contains multiple functional domains and motifs and can disrupt regulation of many signaling pathways and cellular functions. However, the role of specific domains and motifs of Bcr-Abl or of specific signaling pathways in the complex in vivo pathogenesis of CML is not completely known. We have previously shown that expression of Bcr-Abl in bone marrow cells by retroviral transduction efficiently induces a myeloproliferative disorder (MPD) in mice resembling human CML. We have also shown that the Abl kinase activity within Bcr-Abl is essential for Bcr-Abl leukemogenesis, yet activation of the Abl kinase without Bcr sequences is not sufficient to induce MPD in mice. In this study we investigated the role of Bcr sequences within Bcr-Abl in inducing MPD using this murine model for CML. We found that the NH(2)-terminal coiled-coil (CC) domain was both essential and sufficient, even though not efficient, to activate Abl to induce an MPD in mice. Interestingly, deletion of the Src homology 3 domain complemented the deficiencies of the CC-deleted Bcr-Abl in inducing MPD in mice. We further demonstrated that the Grb2 binding site at Y177 played an important role in efficient induction of MPD. These studies directly demonstrated the important roles of Bcr sequences in induction of MPD by Bcr-Abl.

The SH2 domain of bcr-Abl is not required to induce a murine myeloproliferative disease; however, SH2 signaling influences disease latency and phenotype

Bcr-Abl plays a critical role in the pathogenesis of chronic myelogenous leukemia (CML). It was previously shown that expression of Bcr-Abl in bone marrow cells by retroviral transduction efficiently induces a myeloproliferative disorder (MPD) in mice resembling human CML. This in vivo experimental system allows the direct determination of the effect of specific domains of Bcr-Abl, or specific signaling pathways, on the complex in vivo pathogenesis of CML. In this report, the function of the SH2 domain of Bcr-Abl in the pathogenesis of CML is examined using this murine model. It was found that the Bcr-Abl SH2 mutants retain the ability to induce a fatal MPD but with an extended latency compared with wild type (wt) Bcr-Abl. Interestingly, in contrast to wt Bcr-Abl-induced disease, which is rapid and monophasic, the disease caused by the Bcr-Abl SH2 mutants is biphasic, consisting of an initial B-lymphocyte expansion followed by a fatal myeloid proliferation. The B-lymphoid expansion was diminished in mixing experiments with bcr-abl/DeltaSH2 and wt bcr-abl cells, suggesting that the Bcr-Abl-induced MPD suppresses B-lymphoid expansion.

Bcr-Abl has a greater intrinsic capacity than v-Abl to induce the neoplastic expansion of myeloid cells

The Bcr-Abl/p210 fusion protein plays a primary role in the pathogenesis of chronic myelogenous leukemia (CML). Abelson murine leukemia virus, which encodes v-Abl/p160, induces a pre-B cell leukemia/lymphoma in mice. It has been unclear whether the apparent specificity of these two abl oncogenes for myeloid versus lymphoid neoplasms is due to specific intrinsic properties of these Abl oncoproteins, or due to the properties of the target cells expressing them. We have recently shown that expression of Bcr-Abl in bone marrow cells by retroviral transduction efficiently induces a myeloproliferative disorder in mice resembling human CML. In this study, we compared Bcr-Abl/p210 and v-Abl/p160 in this mouse CML model. We found that early in the course of disease, both Bcr-Abl/p210 and v-Abl/p160 expanded early immature hematopoietic cells. Later Bcr-Abl/p210 selectively expanded myeloid cells while v-Abl/p160 primarily induced the rapid in vivo expansion of B lymphoblastic cells, along with a minor population of myeloid cells. In vitro, Bcr-Abl/p210 induced more growth of myeloid colonies from 5-fluorouracil treated bone marrow than v-Abl/p160. These results, obtained under equal bone marrow transduction/transplantation conditions, indicate that Bcr-Abl/p210 has a greater intrinsic capacity than v-Abl/p160 to induce the neoplastic growth of myeloid cells. In addition, we found that cultured cells expressing Bcr-Abl/p210 had more activated STAT5 than cells that expressed v-Abl/p160. This suggests that activation of STAT5 might be one part of the mechanism of abl oncogene disease specificity.

A simple copper(II)-L-histidine system for efficient hydrolytic cleavage of DNA

Copper(II)-L-histidine complexes effectively promote the cleavage of plasmid DNA and dideoxynucleotide dApdA at physiological pH and temperature. Studies of the mechanism of plasmid DNA cleavage by added radical scavengers, using rigorously anaerobic experiments, analyses for malondialdehyde-like products, religation assays, and HPLC analyses, indicate that DNA cleavage mediated by Cu(L-His) occurs via a hydrolytic path. The hydrolytic cleavage rate constants at 37 degrees C are estimated to be 0.76 h-1 for the decrease of form I and 0.25 h-1 for the increase of form III. The phosphoimager picture reveals that Cu(L-His) cleaves DNA with a certain sequence specificity (preferentially at 5'-GT-3'). The dinucleotide hydrolysis shows, with [Cu(L-His)] = 0.8 mM, rate enhancement factors of > 10(8). Interestingly, histidine-metal ion interactions (with Cu(II), Ni(II), Zn(II), etc.) have been used for various applications, e.g., protein purification, cross-linking, and targeting proteins to lipid bilayers. Our findings may provide the basis for developing new applications and new ways to design more effective and useful catalysts for DNA cleavage. Cu(L-His) is one of only a few well-defined metal complexes demonstrated to hydrolytically cleave dideoxynucleotides and DNA.

Human AML1/MDS1/EVI1 fusion protein induces an acute myelogenous leukemia (AML) in mice: a model for human AML

The human t(3;21)(q26;q22) translocation is found as a secondary mutation in some cases of chronic myelogenous leukemia during the blast phase and in therapy-related myelodysplasia and acute myelogenous leukemia. One result of this translocation is a fusion between the AML1, MDS1, and EVI1 genes, which encodes a transcription factor of approximately 200 kDa. The role of the AML1/MDS1/EVI1 (AME) fusion gene in leukemogenesis is largely unknown. In this study, we analyzed the effect of the AME fusion gene in vivo by expressing it in mouse bone marrow cells via retroviral transduction. We found that mice transplanted with AME-transduced bone marrow cells suffered from an acute myelogenous leukemia (AML) 5-13 mo after transplantation. The disease could be readily transferred into secondary recipients with a much shorter latency. Morphological analysis of peripheral blood and bone marrow smears demonstrated the presence of myeloid blast cells and differentiated but immature cells of both myelocytic and monocytic lineages. Cytochemical and flow cytometric analysis confirmed that these mice had a disease similar to the human acute myelomonocytic leukemia. This murine model for AME-induced AML will help dissect the molecular mechanism of AML and the molecular biology of the AML1, MDS1, and EVI1 genes.

Expression of interferon consensus sequence binding protein (ICSBP) is downregulated in Bcr-Abl-induced murine chronic myelogenous leukemia-like disease, and forced coexpression of ICSBP inhibits Bcr-Abl-induced myeloproliferative disorder

Chronic myelogenous leukemia (CML) is a clonal myeloproliferative disorder resulting from the neoplastic transformation of a hematopoietic stem cell. The majority of cases of CML are associated with the (9;22) chromosome translocation that generates the bcr-abl chimeric gene. Alpha interferon (IFN-alpha) treatment induces hematological remission and prolongs life in 75% of CML patients in the chronic phase. It has been shown that mice deficient in interferon consensus sequence binding protein (ICSBP), a member of the interferon regulatory factor family, manifest a CML-like syndrome. We have shown that expression of Bcr-Abl in bone marrow (BM) cells from 5-fluorouracil (5-FU)-treated mice by retroviral transduction efficiently induces a myeloproliferative disease in mice resembling human CML. To directly test whether icsbp can function as a tumor suppressor gene, we examined the effect of ICSBP on Bcr-Abl-induced CML-like disease using this murine model for CML. We found that expression of the ICSBP protein was significantly decreased in Bcr-Abl-induced CML-like disease. Forced coexpression of ICSBP inhibited the Bcr-Abl-induced colony formation of BM cells from 5-FU-treated mice in vitro and Bcr-Abl-induced CML-like disease in vivo. Interestingly, coexpression of ICSBP and Bcr-Abl induced a transient B-lymphoproliferative disorder in the murine model of Bcr-Abl-induced CML-like disease. Overexpression of ICSBP consistently promotes rather than inhibits Bcr-Abl-induced B lymphoproliferation in a murine model where BM cells from non-5-FU-treated donors were used, indicating that ICSBP has a specific antitumor activity toward myeloid neoplasms. We also found that overexpression of ICSBP negatively regulated normal hematopoiesis. These data provide direct evidence that ICSBP can act as a tumor suppressor that regulates normal and neoplastic proliferation of hematopoietic cells.

Bcr-Abl with an SH3 deletion retains the ability To induce a myeloproliferative disease in mice, yet c-Abl activated by an SH3 deletion induces only lymphoid malignancy

The bcr-abl oncogene plays a critical role in the pathogenesis of chronic myelogenous leukemia (CML). The fusion of Bcr sequences to Abl constitutively activates the Abl protein tyrosine kinase. We have recently shown that expression of Bcr-Abl in bone marrow cells by retroviral transduction efficiently induces in mice a myeloproliferative disease resembling human CML and that Abl kinase activity is essential for Bcr-Abl to induce a CML-like myeloproliferative disease. However, it is not known if activation of the Abl kinase alone is sufficient to induce a myeloproliferative disease. In this study, we examined the role of the Abl SH3 domain of Bcr-Abl in induction of myeloproliferative disease and tested whether c-Abl activated by SH3 deletion can induce a CML-like disease. We found that Bcr-Abl with an Abl SH3 deletion still induced a CML-like disease in mice. In contrast, c-Abl activated by SH3 deletion induced only lymphoid malignancies in mice and did not stimulate the growth of myeloid colonies from 5-fluorouracil-treated bone marrow cells in vitro. These results indicate that Bcr sequences in Bcr-Abl play additional roles in inducing myeloproliferative disease beyond simply activating the Abl kinase domain and that functions of the Abl SH3 domain are either not required or redundant in Bcr-Abl-induced myeloproliferative disease. The results also suggest that the type of hematological neoplasm induced by an abl oncogene is influenced not only by what type of hematopoietic cells the oncogene is targeted into but also by the intrinsic oncogenic properties of the particular abl oncogene. In addition, we found that DeltaSH3 c-Abl induced less activation of Akt and STAT5 than did Bcr-Abl, suggesting that activation of these pathways plays a critical role in inducing a CML-like disease.

Gene encoding polygalacturonase inhibitor in apple fruit is developmentally regulated and activated by wounding and fungal infection

A cDNA encoding polygalacturonase-inhibiting protein (PGIP) from mature apple fruit has been cloned and characterized. The open reading frame encodes a polypeptide of 330 amino acids, in which 24 amino acids at the N-terminus comprise the signal peptide. Apple PGIP contains 10 imperfect leucine-rich repeat sequence motifs averaging 24 amino acids in length. In addition to the 1.3 kb PGIP transcript, the cloned cDNA also hybridized to RNA molecules with sizes of 3.2 and 5.0 kb. Genomic DNA analysis revealed that the apple PGIP probably belongs to a small family of genes. PGIP transcript levels varied in fruit collected at different maturities, suggesting the gene is developmentally regulated. Very high PGIP transcript levels were detected in decayed areas and the tissue adjacent to the inoculation sites of Penicillium expansum and Botrytis cinerea. However, no increase in the amount of PGIP transcript in tissue distant from the decayed region was observed. Wounding on fruit also induced PGIP gene expression but to a much lessser extent when compared with decayed areas. After storage at 0 degrees C for 1 month, the abundance of PGIP transcript in ripe fruit was substantially increased. The PGIP gene in immature and ripe fruit was rapidly up-regulated by fungal infections, while in stored fruit the induction was very limited and concurred with an increase of fruit susceptibility to fungal colonization. Since PGIP gene expression is regulated by fruit development and responds to wounding, fungal infection and cold storage, these observations suggest that apple PGIP may have multiple roles during fruit development and stress response.

Polarized distribution of Bcr-Abl in migrating myeloid cells and co-localization of Bcr-Abl and its target proteins

Bcr-Abl plays a critical role in the pathogenesis of Philadelphia chromosome-positive leukemia. Although a large number of substrates and interacting proteins of Bcr-Abl have been identified, it remains unclear whether Bcr-Abl assembles multi-protein complexes and if it does where these complexes are within cells. We have investigated the localization of Bcr-Abl in 32D myeloid cells attached to the extracellular matrix. We have found that Bcr-Abl displays a polarized distribution, colocalizing with a subset of filamentous actin at trailing portions of migrating 32D cells, and localizes on the cortical F-actin and on vesicle-like structures in resting 32D cells. Deletion of the actin binding domain of Bcr-Abl (Bcr-AbI-AD) dramatically enhances the localization of Bcr-Abl on the vesicle-like structures. These distinct localization patterns of Bcr-Abl and Bcr-Abl-AD enabled us to examine the localization of Bcr-Abl substrate and interacting proteins in relation to Bcr-Abl. We found that a subset of biochemically defined target proteins of Bcr-Abl redistributed and co-localized with Bcr-Abl on F-actin and on vesicle-like structures. The co-localization of signaling proteins with Bcr-Abl at its sites of localization supports the idea that Bcr-Abl forms a multi-protein signaling complex, while the polarized distribution and vesicle-like localization of Bcr-Abl may play a role in leukemogenesis.

Bcr-Abl efficiently induces a myeloproliferative disease and production of excess interleukin-3 and granulocyte-macrophage colony-stimulating factor in mice: a novel model for chronic myelogenous leukemia

The bcr-abl oncogene plays a critical role in causing chronic myelogenous leukemia (CML). Effective laboratory animal models of CML are needed to study the molecular mechanisms by which the bcr-abl oncogene acts in the disease progression of CML. We used a murine stem cell retroviral vector (MSCV) to transduce the bcr-abl/p210 oncogene into mouse bone marrow cells and found that expression of Bcr-Abl/p210 induced a myeloproliferative disorder that resembled the chronic phase of human CML in 100% of bone marrow transplanted mice in about 3 weeks. This CML-like disease was readily transplanted to secondary recipient mice. Multiple clones of infected cells were expanded in the primary recipients, but the leukemia was primarily monoclonal in the secondary recipient mice. Mutation analysis demonstrated that the protein tyrosine kinase activity of Bcr-Abl/p210 was essential for its leukemogenic potential in vivo. Interestingly, we found that the leukemic cells expressed excess interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in the diseased mice. These studies demonstrate that expression of Bcr-Abl can induce a CML-like leukemia in mice much more efficiently and reproducibly than in previously reported mouse CML models, probably due to efficient expression in the correct target cell(s). Our first use of this model for analysis of the molecular mechanisms involved in CML raises the possibility that excess expression of hematopoietic growth factors such as IL-3 and GM-CSF may contribute to the clinical phenotype of CML.

Identification of Nck family genes, chromosomal localization, expression, and signaling specificity

Already a dozen molecules share binding to the Src homology (SH) 3 domains of human Nck, an SH3-SH3-SH3-SH2 adapter protein. We reason that there may be multiple gene members of Nck to accommodate the large binding repertoires. Here we report identification of novel human and mouse Nck genes and rename them as the Nckalpha and Nckbeta genes (including the human Nckalpha, human Nckbeta, mouse Nckalpha, and mouse Nckbeta genes). Nckalpha and Nckbeta share 68% amino acid identity, whereas the two Nckalpha and two Nckbeta across the species show 96% identity to each other. The human Nckbeta gene is mapped to 2q12, whereas the human Nckalpha gene has previously been mapped at 3q21. Antibodies specifically against Nckalpha and Nckbeta detect Nckalpha and Nckbeta with an identical molecular mass in the same cells of various origins. Ectopically expressed Nckbeta, but not its SH2 domain mutant, strongly inhibits epidermal growth factor- and platelet-derived growth factor-stimulated DNA synthesis. Consistently, epidermal growth factor receptor and platelet-derived growth factor receptor preferentially interact with Nckbeta over Nckalpha in vitro. This study indicates that Nck is a multiple gene family and that each gene may have its own signaling specificity. Because previous anti-Nck (human Nckalpha) antibodies cross-react with Nckbeta, reassessment of those studies with specific Nck genes would be necessary.

[Effects of zinc deficiency in fodder on brain development, learning and memory in rats]

Zinc deficiency (ZD) model was established in young rats starting from their lactation period. Effects of ZD in fodder on brain development and learning and memory were observed with electron microscopy and neurobiochemical and electroneurophysiological methods, and its mechanism was studied. Results showed that 1. brain weight, hippocampal weight, and serum and hippocampal zinc concentrations were significantly lower in ZD group than those in controls; 2. proportion of induced long-term potentiation (LTP) was zero in ZD group and proportion of active avoidance response decreased profoundly in ZD group, significantly lower than that in normal controls whose LTP proportion was 100%; 3. concentrations of excitatory and inhibitory amino acids, glutamic acid, gamma-aminobutyric acid in cerebral cortex and hippocampus and nitrous oxide in hippocampus were significantly higher in ZD group than those in normal one, and content of somatostatin in hippocampus and DNA in pyramidocytes were significantly lower in ZD group than those in normal one; and 4. number of synaptic vesicles in pyramidocytes of hippocampus decreased obviously in ZD group. It suggests that brain development and function are obviously affected by fodder zinc deficiency in rats.

[Study on evaluating quality of analgini powder pharmaceuticals by near infrared reflectance spectroscopy]

The possibility of using near-infrared reflectance spectroscopy for the evaluating quality of analgini powder pharmaceuticals was investigated. We used the multivariate statistical classification technique to identify true, poor and false phamaceuticals of analgini from their first derivative spectra successfully. The results are satisfactory.

Association of Src tyrosine kinase with a human potassium channel mediated by SH3 domain

The human Kv1.5 potassium channel (hKv1.5) contains proline-rich sequences identical to those that bind to Src homology 3 (SH3) domains. Direct association of the Src tyrosine kinase with cloned hKv1.5 and native hKv1.5 in human myocardium was observed. This interaction was mediated by the proline-rich motif of hKv1.5 and the SH3 domain of Src. Furthermore, hKv1.5 was tyrosine phosphorylated, and the channel current was suppressed, in cells coexpressing v-Src. These results provide direct biochemical evidence for a signaling complex composed of a potassium channel and a protein tyrosine kinase.

The stress response to ionizing radiation involoves c-Abl-dependent phosphorylation of SHPTP1

c-Abl is a nonreceptor tyrosine kinase that is activated by certain DNA-damaging agents. The present studies demonstrate that nuclear c-Abl binds constitutively to the protein tyrosine phosphatase SHPTP1. Treatment with ionizing radiation is associated with c-Abl-dependent tyrosine phosphorylation of SHPTP1. The results demonstrate that the SH3 domain of c-Abl interacts with a WPDHGVPSEP motif (residues 417-426) in the catalytic domain of SHPTP1 and that c-Abl phosphorylates C terminal Y536 and Y564 sites. The functional significance of the c-Abl-SHPTP1 interaction is supported by the demonstration that, like c-Abl, SHPTP1 regulates the induction of Jun kinase activity following DNA damage. These findings indicate that SHPTP1 is involved in the response to genotoxic stress through a c-Abl-dependent mechanism.

A conserved proline-rich region of the Saccharomyces cerevisiae cyclase-associated protein binds SH3 domains and modulates cytoskeletal localization

Saccharomyces cerevisiae cyclase-associated protein (CAP or Srv2p) is multifunctional. The N-terminal third of CAP binds to adenylyl cyclase and has been implicated in adenylyl cyclase activation in vivo. The widely conserved C-terminal domain of CAP binds to monomeric actin and serves an important cytoskeletal regulatory function in vivo. In addition, all CAP homologs contain a centrally located proline-rich region which has no previously identified function. Recently, SH3 (Src homology 3) domains were shown to bind to proline-rich regions of proteins. Here we report that the proline-rich region of CAP is recognized by the SH3 domains of several proteins, including the yeast actin-associated protein Abp1p. Immunolocalization experiments demonstrate that CAP colocalizes with cortical actin-containing structures in vivo and that a region of CAP containing the SH3 domain binding site is required for this localization. We also demonstrate that the SH3 domain of yeast Abp1p and that of the yeast RAS protein guanine nucleotide exchange factor Cdc25p complex with adenylyl cyclase in vitro. Interestingly, the binding of the Cdc25p SH3 domain is not mediated by CAP and therefore may involve direct binding to adenylyl cyclase or to an unidentified protein which complexes with adenylyl cyclase. We also found that CAP homologous from Schizosaccharomyces pombe and humans bind SH3 domains. The human protein binds most strongly to the SH3 domain from the abl proto-oncogene. These observations identify CAP as an SH3 domain-binding protein and suggest that CAP mediates interactions between SH3 domain proteins and monomeric actin.

c-Abl activation regulates induction of the SEK1/stress-activated protein kinase pathway in the cellular response to 1-beta-D-arabinofuranosylcytosine

Previous work has shown that treatment of cells with the antimetabolite 1-beta-D-arabinofuranosylcytosine (ara-C) is associated with induction of the c-jun gene. The present studies demonstrate that ara-C activates the c-Abl non-receptor tyrosine kinase. We also demonstrate that activity of the stress-activated protein kinase (SAP kinase/JNK) is increased in ara-C-treated cells. Using cells deficient in c-Abl (Abl-/-) and after introduction of the c-abl gene, we show that ara-C-induced c-Abl activity is necessary for the stimulation of SAP kinase. Other studies using cells transfected with a SEK1 dominant negative demonstrate that ara-C-induced SAP kinase activity is SEK1-dependent. Furthermore, we show that overexpression of truncated c-Abl results in activation of the SEK1/SAP kinase cascade.

Activation of the c-Abl tyrosine kinase in the stress response to DNA-damaging agents

The product of the c-abl gene is a non-receptor tyrosine kinase that is localized to the nucleus and cytoplasm. The precise function of c-Abl is unknown. Here we show that ionizing radiation activates c-Abl. Similar results were obtained with the alkylating agents cis-platinum and mitomycin C. We also demonstrate that cells deficient in c-Abl fail to activate Jun kinase (JNK/SAP kinase) after ionizing radiation or alkylating agent exposure and that reconstitution of c-Abl in these cells restores that response. In contrast, the stress response to tumour-necrosis factor is stimulated by a c-Abl-independent mechanism. These findings indicate that c-abl is involved in the stress response to DNA-damaging agents.

SH2 and SH3 domains as molecular adhesives: the interactions of Crk and Abl

The Src homology domains SH2 and SH3 are modular components present in many signal transduction proteins. They allow rapid formation of stable protein complexes and may also regulate protein function through intramolecular binding events. SH2 domains recognize phosphotyrosyl residues in a specific sequence context, while SH3 domains recognize a PxxP motif and additional residues that mediate binding specificity.

Abl protein-tyrosine kinase selects the Crk adapter as a substrate using SH3-binding sites

To understand the normal and oncogenic functions of the protein-tyrosine kinase Abl, the yeast two-hybrid system has been used for identifying proteins that interact with it. One interacting protein is Crk-I, an SH3/SH2-containing adapter protein that was originally identified as the oncogenic element in the avian sarcoma virus CT10. Direct interaction between the Crk-I SH3 and Abl at novel, approximately 10 amino acid sites just carboxy-terminal to the Abl kinase domain occurs in vitro and in mammalian cells. There is a nearby site specific for binding another adapter, Nck, and these sites also bind Grb-2. When bound to Abl, Crk-I was phosphorylated on tyrosine. Thus, the SH3-binding sites on Abl serve as substrate recognition sites for the relatively nonspecific kinase of Abl. In Crk-I-transformed cells, Crk-I associates with endogenous c-Abl and is phosphorylated on tyrosine. The association of Crk and Abl suggests that Abl could play a role in v-Crk and Crk-I transformation and that normal Abl function may be partly mediated through bound adapter molecules.

Transgenic mice and the pathogenesis of poliomyelitis

Transgenic mice expressing the cell receptor for poliovirus have been generated and are susceptible to poliovirus infection. TgPVR mice have been used to answer questions about the pathogenesis of poliovirus infection. Despite the widespread pattern of PVR expression, poliovirus infection in TgPVR mice is restricted to only a few sites, indicating that poliovirus tropism is not controlled solely by the ability of cells to bind virus. After intramuscular inoculation, poliovirus travels to the spinal cord by axonal transport. This route of entry into the central nervous system may play a role in the pathogenesis of poliovirus infections in humans.

Identification of a ten-amino acid proline-rich SH3 binding site

The Src homology 3 (SH3) region is a small protein domain present in a very large group of proteins, including cytoskeletal elements and signaling proteins. It is believed that SH3 domains serve as modules that mediate protein-protein associations and, along with Src homology 2 (SH2) domains, regulate cytoplasmic signaling. The SH3 binding sites of two SH3 binding proteins were localized to a nine- or ten-amino acid stretch very rich in proline residues. Similar SH3 binding motifs exist in the formins, proteins that function in pattern formation in embryonic limbs of the mouse, and one subtype of the muscarinic acetylcholine receptor. Identification of the SH3 binding site provides a basis for understanding the interaction between the SH3 domains and their targets.

Poliovirus spreads from muscle to the central nervous system by neural pathways

A transgenic mouse model was used to address an unsolved question in the pathogenesis of poliomyelitis: how poliovirus invades the central nervous system (CNS). LD50 values for intramuscular and intracerebral inoculation of poliovirus in transgenic mice expressing poliovirus receptors (TgPVR mice) were similar. After intramuscular inoculation with poliovirus, paralysis was observed first in the inoculated limb. In contrast, localization of initial paralysis to the inoculated limb was not observed in normal mice inoculated intramuscularly with the mouse-adapted P2/Lansing poliovirus strain. After intramuscular inoculation, infectious poliovirus was first detected in the inferior segment of the spinal cord, then in the superior spinal cord and the brain. Sciatic nerve transection blocked poliovirus spread to the spinal cord after inoculation into the hindlimb footpad of TgPVR mice. These results demonstrate that in TgPVR mice, poliovirus spreads from muscle to the CNS through nerve pathways and that expression of the poliovirus receptor plays an important role in viral spread by this route.

Human poliovirus receptor gene expression and poliovirus tissue tropism in transgenic mice

Expression of the human poliovirus receptor (PVR) in transgenic mice results in susceptibility to poliovirus infection. In the primate host, poliovirus infection is characterized by restricted tissue tropism. To determine the pattern of poliovirus tissue tropism in PVR transgenic mice, PVR gene expression and susceptibility to poliovirus infection were examined by in situ hybridization. PVR RNA is expressed in transgenic mice at high levels in neurons of the central and peripheral nervous system, developing T lymphocytes in the thymus, epithelial cells of Bowman's capsule and tubules in the kidney, alveolar cells in the lung, and endocrine cells in the adrenal cortex, and it is expressed at low levels in intestine, spleen, and skeletal muscle. After infection, poliovirus replication was detected only in neurons of the brain and spinal cord and in skeletal muscle. These results demonstrated that poliovirus tissue tropism is not governed solely by expression of the PVR gene nor by accessibility of cells to virus. Although transgenic mouse kidney tissue expressed poliovirus binding sites and was not a site of poliovirus replication, when cultivated in vitro, kidney cells developed susceptibility to infection. Identification of the changes in cultured kidney cells that permit poliovirus infection may provide information on the mechanism of poliovirus tissue tropism.

[Isolation and physico-chemical properties of polysaccharides from the root of Cynanchum auriculatum Royle ex Wight]

Three polysaccharides AC-A, AC-B, AC-C were isolated and purified from the water extract of the root of Cynanchum auriculatum. The molecular weight of AC-A, AC-B and AC-C were 28000, 51000 and 117000 respectively. All these polysaccharides were composed of rhamnose, arabinose, xylose, galactose, mannose and glucose.