Lysophosphatidylcholine generates superoxide anions through activation of phosphatidylinositol 3-kinase in human neutrophils

Lysophosphatidylcholine (LPC) accumulates in inflammatory tissues, where neutrophils are recruited to generate superoxide anions (O2.-). Here, we show that LPC stimulates O2.- generation in human neutrophils and that the activity is inhibited with phosphatidylinositol 3-kinase (PI3 kinase) inhibitors, but not with protein kinase C (PKC) inhibitors. Furthermore, we demonstrate that LPC activates PI3 kinase in neutrophils. Thus, LPC might contribute to host defense by generating O2.- in neutrophils through PI3 kinase activation, but not through PKC activation.

Isolation of a class IV chitin synthase gene from a zygomycete fungus, Rhizopus oligosporus

We found the presence of DNA sequence which shows sequence similarity to the class IV chitin synthase gene (CHS3) of Saccharomyces cerevisiae in the genome of 14 Rhizopus species which belong to zygomycetes. We cloned a gene (chs3), which might correspond to one of these homologous sequences, from Rhizopus oligosporus by low stringency plaque hybridization probed with CHS3. The deduced amino acid sequence of this gene showed highest similarity to the class IV chitin synthase of Neurospora crassa (46.7% identity over 1087 amino acids), showing that this gene encodes a class IV chitin synthase. Northern analysis revealed the differential expression pattern of this gene in the asexual life cycle with highest expression in the early stage of asexual spore formation. This is the first report of the isolation and analysis of a class IV chitin synthase gene from zygomycete fungi.

Coexpression of hepatocyte growth factor and c-Met proto-oncogene product in synovial sarcoma

Hepatocyte growth factor (HGF) is a heterodimeric polypeptide growth factor that has pleiotropic roles, including those of mitogen, motogen and morphogen. The HGF receptor is characterized as a c-Met proto-oncogene product (c-Met), which is a heterodimeric tyrosine kinase receptor. Hepatocyte growth factor acts as a mediator between the mesenchymal and epithelial tissues because HGF is produced by mesenchymal cells and c-Met is mainly expressed on various epithelial cells. Furthermore, the HGF/c-Met system plays an important role in embryogenesis and the regeneration of various organs. Synovial sarcoma (SS) are unique sarcoma that show epithelial differentiation, but little is known about their histogenesis. The expression of HGF and c-Met was examined by immunohistochemistry in SS specimens from 12 patients (six each of biphasic and monophasic fibrous types). Immunohistochemical coexpression of HGF and c-Met was demonstrated in the epithelial component of five biphasic SS, while only c-Met was expressed in the epithelioid nests of three monophasic fibrous SS. The spindle cell component was negative for HGF and c-Met. In SS, positivity for epithelial markers, such as cytokeratins and epithelial membrane antigen, was diffusely observed in the epithelial component and was focally observed in spindle cells, while vimentin was positive predominantly in the spindle cell component. The areas expressing HGF and c-Met corresponded to distinct epithelial structures; however, HGF and c-Met expression were not found in any other tumor cells expressing epithelial markers in the spindle cell component of SS. Considering the morphogenic effect of HGF, which has been known to be one of its most important roles, the unique immunohistochemical localization of HGF and c-Met in SS suggests that the HGF/c-Met system may be closely related to the formation of epithelial (glandular) structures in biphasic SS.

Familial neurilemoma of the spinal cord in a mother and daughter

Neurilemoma of the spinal cord occurred in a mother and daughter. Case 1 was a 75-year-old woman with gait disturbance. Examination revealed weakness of the lower extremities, and magnetic resonance (MR) imaging showed an intradural extramedullary tumor at T12. After laminectomy, the histologic diagnosis was mixed Antoni type A and B neurilemoma. Case 2 was a 48-year-old woman (daughter of case 1). She presented with cervical pain and numbness of both hands. Examination revealed weakened intrinsic muscles of the right hand and paresthesia of the right upper arm. MR imaging showed a giant hourglass-shaped extradural tumor at C2 and C3. The histologic diagnosis was Antoni type A neurilemoma. Only six families with neurilemoma have been reported, including our patients. Gene analysis of such patients may clarify the etiology of neurilemoma.

Chicken monoclonal antibodies against synthetic bovine prion protein peptide

Chicken monoclonal antibodies (mAbs) were developed against bovine prion protein (PrP) peptide. Chickens immunized with bovine PrP peptide B204 (amino acid residues 204-220) coupled to keyhole limpet hemocyanin produced specific antibodies to the peptide as determined by an enzyme-linked immunosorbent assay (ELISA) using the B204 peptide coupled to ovalbumin as target antigen. From a fusion experiment using the chicken fusion partner cell line MuH1 and immune spleen cells, 19 mAbs reactive with B204 were generated. These mAbs were subdivided into five groups based on competitive ELISA using B204 and four 10-amino acid peptides. These five groups included all combinations expected based on comparison of amino acid sequences among the five species, bovine, mouse, human, sheep and hamster, examined. These results indicate that the chicken mAb system is a suitable technique for immunological analysis of PrP in mammals.

Isolation and characterization of EPD1, an essential gene for pseudohyphal growth of a dimorphic yeast, Candida maltosa

Additional copies of the centromeric DNA (CEN) region induce pseudohyphal growth in a dimorphic yeast, Candida maltosa (T. Nakazawa, T. Motoyama, H. Horiuchi, A. Ohta, and M. Takagi, J. Bacteriol. 179:5030-5036, 1997). To understand the mechanism of this transition, we screened the gene library of C. maltosa for sequences which could suppress this morphological change. As a result, we isolated the 5' end of a new gene, EPD1 (for essential for pseudohyphal development), and then cloned the entire gene. The predicted amino acid sequence of Epdlp was highly homologous to those of Ggp1/Gas1/Cwh52p, a glycosylphosphatidylinositol-anchored protein of Saccharomyces cerevisiae, and Phr1p and Phr2p of Candida albicans. The expression of EPD1 was moderately regulated by environmental pH. A homozygous EPD1 null mutant showed some morphological defects and reduction in growth rate and reduced levels of both alkali-soluble and alkali-insoluble beta-glucans. Moreover, the mutant could not undergo the transition from yeast form to pseudohyphal form induced by additional copies of the CEN sequence at pH 4 or by n-hexadecane at pH 4 or pH 7, suggesting that EPD1 is not essential for yeast form growth but is essential for transition to the pseudohyphal form. Overexpression of the amino-terminal part of Epd1p under the control of the GAL promoter suppressed the pseudohyphal development induced by additional copies of the CEN sequence, whereas overexpression of the full-length EPD1 did not. This result and the initial isolation of the 5' end of EPD1 as a suppressor of the pseudohyphal growth induced by the CEN sequence suggest that the amino-terminal part of Epd1p may have a dominant-negative effect on the functions of Epd1p in the pseudohyphal growth induced by the CEN sequence.

Foreign body gonitis caused by a broken poly-L-lactic acid screw

Poly-L-lactic acid (PLLA), a biodegradable polymer, is generally considered to be gradually degraded without causing any severe tissue reaction. However, we encountered a patient who developed foreign body gonitis caused by screw breakage after fixation of an intercondylar prominence fracture with PLLA screws. This case suggests that care should be taken when PLLA materials are used to fix intraarticular fractures.

The effects of thermal and mechanical stimulation on blood flow in healthy and inflamed gingiva in man

The purpose of this study was to compare the state of the microcirculation in healthy gingiva with that in untreated, inflamed gingiva in humans. Reflection photoplethysmography (RP) was used to record blood flow from 13 clinically healthy, attached gingival sites in seven adults and 11 inflamed sites in seven patients. Changes in the pulse amplitude of the RP signal were measured before and after application of thermal (cold and hot water) and mechanical (brushing) stimuli to the gingiva. Hot water and brushing, but not cold water, produced a significant increase in the pulse amplitude in healthy gingiva (p < 0.05, Friedman analysis and Student-Newman Keuls test). None of the stimuli produced a significant change in inflamed gingiva. In neither group of participants was there a significant correlation (Spearman rank correlation coefficient) between vascular responsiveness and age. The results indicated that vasomotor control may be impaired in inflamed gingiva.

Cloning and characterization of a chitinase-encoding gene (chiA) from Aspergillus nidulans, disruption of which decreases germination frequency and hyphal growth

We cloned a chitinase-encoding gene from Aspergillus nidulans by polymerase chain reaction using degenerated oligonucleotide primers designed from the conserved amino acid sequences among chitinases from yeasts and Rhizopus spp. The cloned gene, named chiA, encoded a polypeptide consisting of 660 amino acids. Disruption of chiA had no effect on hyphal or conidiophore morphology, but germination frequency and hyphal growth rate decreased substantially. Expression of chiA was investigated using Escherichia coli beta-galactosidase as a reporter enzyme. The beta-galactosidase activity was present during hyphal growth and increased twice as the conidiophores developed. In situ staining of beta-galactosidase activity found high expression in metulae, phialides, and conidia during conidiophore development, indicating that the expression of chiA is developmentally regulated. This is the first report to isolate a chitinase gene from A. nidulans and investigate its functions using the gene disruption technique and gene fusion methods in filamentous fungi.

Cleavage of rabaptin-5 blocks endosome fusion during apoptosis

Cells undergoing apoptosis exhibit striking changes in membrane organization, including plasma membrane blebbing and invagination, vacuolation and fragmentation of organelles, and alterations in the surface expression of receptors. The underlying mechanisms for these changes are unknown, though alterations in vesicular fusion are likely to play a role. Using a cell-free system based on Xenopus laevis egg extracts we have found that endosome fusion is blocked during apoptosis. Inhibition of fusion is prevented by Bcl-2 or Bcl-xL, two negative regulators of apoptosis, or by specific inhibitors of members of the caspase family of apoptotic proteases. Selective cleavage of Rabaptin-5, an essential and rate-limiting component of endosome fusion, is responsible for the loss of fusion activity. Cleavage of Rabaptin-5 also occurs in cellular models for apoptosis. These results suggest that inactivation of Rabaptin-5 and inhibition of vesicle transport lead to fragmentation of endosomes and inhibition of the endocytic pathway during the execution phase of apoptosis. We propose that parallel changes to other membrane transport pathways would give rise to general membrane fragmentation in apoptotic cells. These changes are likely to play an important role in the generation of apoptotic bodies and their recognition by phagocytosing cells.

Production of recombinant Der fI with the native IgE-binding activity using a baculovirus expression system

Der fI is a cysteine protease contained in feces of mites and is one of major mite allergens. Recombinant Der fI (reDer fI) that is produced using a baculovirus expression system contains pro-sequences of different lengths. Most of these can be removed by acid treatment. However, IgE-binding activity of acid-treated reDer fI is lower than that of native Der fI at high protein concentrations, and N-terminal amino acids of acid-treated reDer fI are not uniform. Now, a method for processing of the pro-sequence has been developed by producing reDer fI E(-1)K with baculovirus expression system in which the carboxy terminal amino acid of the pro-sequence (glutamate) was replaced by lysine using site directed mutagenesis. No difference in the amount of production was observed upon introducing the mutation into the pro-sequence. Addition of lysylendopeptidase into the culture medium led to processing of the pro-sequence of reDer fI E(-1)K and proceeded the degradation of the other proteins in the medium. Lysylendopeptidase-treated reDer fI E(-1)K was easily purified with an anion exchange column, resulting in 20% increase of the yield. Lysylendopeptidase-treated reDer fI E(-1)K obtained through these processes was compared with the native Der fI. Although some differences were found in protease activity and reactivity with lectins, their N-terminal amino acid and the IgE-binding activity were the same as those of the native one, indicating its usefulness for diagnostic purpose.

A novel Rab5 GDP/GTP exchange factor complexed to Rabaptin-5 links nucleotide exchange to effector recruitment and function

The small GTPase Rab5 plays an essential role in endocytic traffic. Rab GDP dissociation inhibitor delivers Rab5 to the membrane, where a nucleotide exchange activity allows recruitment of an effector protein, Rabaptin-5. Here we uncovered a novel 60 kDa Rab5-binding protein, Rabex-5. Rabex-5 forms a tight physical complex with Rabaptin-5, and this complex is essential for endocytic membrane fusion. Sequencing of mammalian Rabex-5 by nanoelectrospray mass spectrometry and cloning revealed striking homology to Vps9p, a yeast protein implicated in endocytic traffic. Rabex-5 displays GDP/GTP exchange activity on Rab5 upon delivery of the GTPase to the membrane. This demonstrates that a soluble exchange factor coupled to a Rab effector translocates from cytosol to the membrane, where the complex stabilizes the GTPase in the active state.

Accumulation of misfolded protein aggregates leads to the formation of russell body-like dilated endoplasmic reticulum in yeast

RNAP-1, an aspartic proteinase from a filamentous fungus Rhizopus niveus, is secreted very efficiently in Saccharomyces cerevisiae. It is synthesized first as a precursor form with signal sequence and prosequence in its amino-terminus. Our previous study indicated that the prosequence of RNAP-I had important roles in its correct folding and secretion in yeast, and that a prosequence-deleted derivative of RNAP-I, delta pro, was not secreted but was retained and degraded in the yeast endoplasmic reticulum (ER). In the present study, we show that the accumulation of delta pro in the yeast ER caused elevated synthesis of ER resident chaperones, indicating that delta pro is recognized as an unfolded protein species in the ER. Our biochemical data demonstrated that delta pro formed aggregates which contained BiP, but not protein disulfide isomerase (PDI), in the ER. Immunoelectron microscopical analysis revealed that the delta pro aggregates were indeed visible as electron-dense regions in the ER and nuclear envelope. Such 'chaperone-associated misfolded protein bodies' were observed for the first time in yeast. Morphologies of the ER and nucleus were drastically altered by the accumulation of the delta pro aggregates. The ER lost its flat cisternal shape; the ER lumen extended aberrantly and the ER membrane irregularly proliferated. The misfolded delta pro proteins are probably sorted from the ordinary ER lumen to form the aggregates so that the ER function would not be grossly impaired, and the dilated ER may represent an ER subcompartment where the delta pro aggregates are degraded.

Fc portion of intravenous immunoglobulin suppresses the induction of experimental allergic neuritis

To clarify how intravenous immunoglobulin (IVIg) acts on Guillain-Barré syndrome, we investigated the effects of intact-type IVIg treatment on experimental allergic neuritis (EAN) induced by immunizing with synthetic peptide from bovine P2 protein. Treatment with intact-type IVIg (400 mg/kg/day) on days 0, 7, 14, 15 and 16 after immunization prevented the paralysis, whereas treatment with F(ab')2 failed to alter the clinical course. Intact-type IVIg treatment given on days 0 and 1 showed almost the same efficacy. These results suggest that intact-type IVIg is superior to F(ab')2 in ameliorating the clinical course of EAN and that the Fc portion might affect the immune system.

Circulating promyelocytes and low levels of CD16 expression on polymorphonuclear leukocytes accompany early-onset periodontitis

Early-onset periodontitis (EOP) is characterized by rapidly progressive alveolar bone loss, chemotactic defects of neutrophils, and significant familial aggregation. We found immature myeloid lineage cells, defined as promyelocytes, in the peripheral blood in patients with EOP. A hematological examination of peripheral blood cells showed normal reference values regarding cell proportions. Flow cytometry revealed significantly lower expression of CD16, a glycosylphosphatidylinositol (GPI)-anchored protein, on peripheral neutrophils in patients compared with those in age- and sex-matched healthy controls, whereas the levels of CD11a and CD11b expression were similar. The chemotactic response of neutrophils was lower toward not only formyl-methionyl-leucyl-phenylalanine but also complement fragment C5a than that of healthy controls. The expression of another GPI-anchored protein, CD14, was equally expressed by controls and patients. Therefore, the low level of CD16 expression was not due to the incomplete synthesis of the GPI anchor. GPI anchors of CD16 on neutrophils from controls and patients were both partially resistant to phosphatidylinositol-specific phospholipase C. The presence of promyelocytes in peripheral blood, low expression of CD16, and low chemotactic response of neutrophils suggest that patients with EOP have an abnormal maturation system in myeloid lineage cells in the bone marrow, which may be associated with the onset and course of EOP.

Effect of intraluminal pressure on the intimal thickening in injured rabbit carotid arteries in an organ-culture system

We developed an organ culture system in order to examine the effect of intraluminal pressure on intimal thickening in injured arteries. After endothelial denudation, an excised rabbit common carotid artery was incubated at 37 degrees C in a glass bottle perfused with Dulbecco's modified Eagle medium containing 10% fetal calf serum at a constant flow rate of 6 ml/h at various static pressure of 60, 95, 130, 165, or 200 cmH2O. Intimal thickening, which consisted of smooth muscle cells and extracellular matrix, increased in a time- and pressure-dependent manner up to 130 cmH2O. Excessive pressured (165 and 200 cmH2O), however, caused necrosis in the media. These results suggest that a rise in intraluminal pressure accelerates intimal thickening in injured arteries.

Evidence that part of a centromeric DNA region induces pseudohyphal growth in a dimorphic yeast, Candida maltosa

We observed that a YCp-type vector having the centromeric DNA (CEN) sequence previously isolated from the genome, but not a YRp-type vector lacking the CEN sequence, induced pseudohyphal growth in a dimorphic fungi, Candida maltosa, which had been shown to be closely related to Candida albicans by phylogenetic analysis. Deletion analysis of the CEN sequence revealed that the intact CEN sequence was not required for the induction, but part of it, having partial centromeric activity, was enough for the induction. By screening the gene library of this yeast for the sequences which induced pseudohyphal growth, we isolated three different DNA fragments which also had part of the centromere-like sequence. Partial centromeric activity of these fragments was confirmed by three criteria: low copy number and high stability of the plasmids carrying these fragments and rearrangement at high frequency of the plasmid DNA with one of these fragments plus the CEN sequence. Furthermore, when the GGTAGCG sequence commonly found in one copy in each of these four sequences was mutated in the CEN sequence by site-directed mutagenesis, both partial centromeric activity and pseudohyphal growth-inducing activity of the CEN sequence were lost. These results indicated that part of CEN region with partial centromeric activity induces pseudohyphal growth in C. maltosa. It is suggested that some cellular components which interact with the sequence containing GGTAGCG required for centromeric activity are involved in the regulation of the transition between yeast forms and pseudohyphal forms of the cells.

A novel fungal gene encoding chitin synthase with a myosin motor-like domain

A csmA gene that encodes chitin synthase with a myosin motor-like domain was isolated from the filamentous fungus Aspergillus nidulans. Initially, we obtained the csmA as a homolog of the Aspergillus fumigatus chsE-partial fragment. A large open reading frame encoding a polypeptide of 1,852 a.a. was identified by determining the cDNA sequences. The chitin synthase conserved region was situated at the C-terminus and classified into class V as reported previously. On the other hand, the N-terminal region showed significant similarity to myosin motors and could not be classified into any types of myosins identified so far. Thus, it is suggested that this is the first report of unconventional myosin fused to a metabolic enzyme. The finding of this new type of chitin synthase gene suggests that localization of chitin synthesis may be guided by association with cytoskeletal structures.

Overexpression of resistance-related proteins (metallothioneins, glutathione-S-transferase pi, heat shock protein 27, and lung resistance-related protein) in osteosarcoma. Relationship with poor prognosis

BACKGROUND

The prognosis for patients with osteosarcoma has improved over the past 20 years, mainly due to developments in chemotherapy. Some proteins have been reported to show drug resistance. Theoretically, overexpression of some of these proteins makes treatment difficult, leading to poorer outcome.

METHODS

Specimens taken from conventional osteosarcomas of the extremity bones from 60 patients younger than 30 years were used. In all cases, preoperative oncostatic chemotherapy was undertaken after biopsy. If available, biopsy specimens were also used for sequential comparison. Among resistance-related proteins, expression of metallothioneins (MTs), glutathione-S-transferase pi (GST pi), heat shock protein 27 (Hsp27), and lung resistance-related protein (LRP) was evaluated immunohistochemically in paraffin sections. The log rank test was used for univariate analysis and the Cox regression model for multivariate analysis.

RESULTS

At biopsy, only overexpression of Hsp27 was associated with poor prognosis. At surgery, a relationship was observed between poor prognosis and overexpression of GST pi, Hsp27, and LRP. Groups overexpressing one protein tended to overexpress another. Overexpression of these proteins in surgical specimens also correlated with histologic response to preoperative chemotherapy and clinical stage. In multivariate analysis, Hsp27 overexpression at biopsy was an independent prognostic factor.

CONCLUSIONS

Inherent overexpression of Hsp27 is independently related to poor outcome in osteosarcoma patients. Overexpression of GST pi, Hsp27, and LRP at surgery might be associated with failure of preoperative chemotherapy. Control of the expression of these proteins may improve the outcome for patients with osteosarcoma.

Overexpression of resistance-related proteins (metallothioneins, glutathione-S-transferase pi, heat shock protein 27, and lung resistance-related protein) in osteosarcoma. Relationship with poor prognosis

BACKGROUND

The prognosis for patients with osteosarcoma has improved over the past 20 years, mainly due to developments in chemotherapy. Some proteins have been reported to show drug resistance. Theoretically, overexpression of some of these proteins makes treatment difficult, leading to poorer outcome.

METHODS

Specimens taken from conventional osteosarcomas of the extremity bones from 60 patients younger than 30 years were used. In all cases, preoperative oncostatic chemotherapy was undertaken after biopsy. If available, biopsy specimens were also used for sequential comparison. Among resistance-related proteins, expression of metallothioneins (MTs), glutathione-S-transferase pi (GST pi), heat shock protein 27 (Hsp27), and lung resistance-related protein (LRP) was evaluated immunohistochemically in paraffin sections. The log rank test was used for univariate analysis and the Cox regression model for multivariate analysis.

RESULTS

At biopsy, only overexpression of Hsp27 was associated with poor prognosis. At surgery, a relationship was observed between poor prognosis and overexpression of GST pi, Hsp27, and LRP. Groups overexpressing one protein tended to overexpress another. Overexpression of these proteins in surgical specimens also correlated with histologic response to preoperative chemotherapy and clinical stage. In multivariate analysis, Hsp27 overexpression at biopsy was an independent prognostic factor.

CONCLUSIONS

Inherent overexpression of Hsp27 is independently related to poor outcome in osteosarcoma patients. Overexpression of GST pi, Hsp27, and LRP at surgery might be associated with failure of preoperative chemotherapy. Control of the expression of these proteins may improve the outcome for patients with osteosarcoma.

A fungal chitinase gene fromRhizopus oligosporus confers antifungal activity to transgenic tobacco

We have studied whether a chitinase involved in cell autolysis of a filamentous fungus,Rhizopus oligosporus, can operate as an antifungal defense system in tobacco. Thechi1 gene was introduced into tobacco by theAgrobacterium tumefaciens leaf disc system. Among 22 transgenic tobacco plants, 2 were selected and their individual homozygous progeny, Tch1-1 and Tch2-1, were studied. Chitinase activity in the extracts of young leaves from Tch1-1 or Tch2-1, in which thechi1 gene product was detected by Western blot analysis, was three- to four-fold higher than that from the control plants. A fungal infection assay on the leaves infected with the discomycete pathogensSclerotinia sclerotiorum andBotrytis cinerea revealed that the symptoms observed with these two were remarkably suppressed as compared with the control leaves.

The Aspergillus nidulans genes chsA and chsD encode chitin synthases which have redundant functions in conidia formation [corrected and republished article originally appeared in Mol Gen Genet 1996 Jun; 251(4):442-50]

We previously isolated three chitin synthase genes (chsA, chsB, and chsC) from Aspergillus nidulans. In the present work, we describe the isolation and characterization of another chitin synthase gene, named chsD, from A. nidulans. Its deduced amino acid sequence shows 56.7% and 55.9% amino acid identity, respectively, with Cal1 of Saccharomyces cerevisiae and Chs3 of Candida albicans. Disruption of chsD caused no defect in cell growth or morphology during the asexual cycle and caused no decrease in chitin content in hyphae. However, double disruption of chsA and chsD caused a remarkable decrease in the efficiency of conidia formation, while double disruption of chsC and chsD caused no defect. Thus it appears that chsA and chsD serve redundant functions in conidia formation.