The moleskin gene product is essential for Caudal-mediated constitutive antifungal Drosomycin gene expression in Drosophila epithelia.

The homeobox gene, Caudal, encodes the DNA-binding nuclear transcription factor that plays a crucial role during development and innate immune response. The Drosophila homologue of importin-7 (DIM-7), encoded by moleskin, was identified as a Caudal-interacting molecule during yeast two-hybrid screening. Both mutation of the minimal region of Caudal responsible for moleskin binding and RNA interference (RNAi) of moleskin dramatically inhibited the Caudal nuclear localization. Furthermore, Caudal-mediated constitutive expression of antifungal Drosomycin gene was severely affected in the moleskin-RNAi flies, showing a local Drosomycin expression pattern indistinguishable from that of the Caudal-RNAi flies. These in vivo data suggest that DIM-7 mediates Caudal nuclear localization, which is important for the proper Caudal function necessary for regulating innate immune genes in Drosophila.

Emerging erythromycin resistance among group B streptococci in Korea.

In order to determine possible trends in the susceptibility and distribution of group B streptococci (GBS) serotypes in a Korean population and to elucidate any relationship between the serotypes and the antimicrobial susceptibility patterns found, 185 clinical isolates of GBS were investigated between 1990 and 1998. The rate of erythromycin resistance increased from 0% during the period 1990-1995 to 26% in 1996 and 40% in 1998. The overall rates of resistance to erythromycin and clindamycin were 20% and 22.2%, respectively. GBS serotype V was not detected until 1995, but it was isolated in 1996 and ranked third in frequency (18.8%) in 1997. Among the 37 erythromycin-resistant strains detected, 54.1% and 29.7% were of serotype III and V, respectively. The emerging erythromycin resistance detected among these GBS isolates was mainly due to a sudden increase in the incidence of GBS serotypes with multidrug-resistant phenotypes.

Localization of phospholipase C-gamma1 signaling in caveolae: importance in EGF-induced phosphoinositide hydrolysis but not in tyrosine phosphorylation.

Upon epidermal growth factor treatment, phospholipase C-gamma1 (PLC-gamma1) translocates from cytosol to membrane where it is phosphorylated at tyrosine residues. Caveolae are small plasma membrane invaginations whose structural protein is caveolin. In this study, we show that the translocation of PLC-gamma1 and its tyrosine phosphorylation are localized in caveolae by caveolin-enriched low-density membrane (CM) preparation and immunostaining of cells. Pretreatment of cells with methyl-beta-cyclodextrin (MbetaCD), a chemical disrupting caveolae structure, inhibits the translocation of PLC-gamma1 to CM as well as phosphatidylinositol (PtdIns) turnover. However, MbetaCD shows no effect on tyrosine phosphorylation level of PLC-gamma1. Our findings suggest that, for proper signaling, PLC-gamma1 phosphorylation has to occur at PtdInsP(2)-enriched sites.

Malignant triton tumor of the nasal cavity.

BACKGROUND: Malignant triton tumor is usually an aggressive sarcoma consisting of a malignant schwannoma with rhabdomyoblastic differentiation. However, malignant triton tumor of the nasal cavity is very rare. METHODS: A case report of a 38-year-old woman with polypoid mass, which bled easily in the right nasal cavity, and nasal obstruction is presented with a review of the literature pertaining to this unusual case. RESULTS: The malignant triton tumor was treated with wide surgical excision followed by radiation therapy. Histopathological diagnosis of the malignant triton tumor was made on the surgical specimen. The patient's postoperative course was unremarkable, and follow-up at 5 years reveals no evidence of disease. CONCLUSIONS: A malignant triton tumor in the nasal cavity is a rare disease. Head and neck surgeons should recognize the possibility of malignant triton tumor occurring in the nasal cavity.

Phospholipase D1 is phosphorylated and activated by protein kinase C in caveolin-enriched microdomains within the plasma membrane.

Activities of phospholipase D (PLD) in diverse subcellular organelles have been identified but the details of regulatory mechanisms in such locations are unknown. Protein kinase C (PKC) is a major regulator of PLD. Serine 2, threonine 147, and serine 561 residues of phospholipase D1 (PLD1) were determined as sites of phosphorylation by PKC (Kim, Y., Han, J. M., Park, J. B., Lee, S. D., Oh, Y. S., Chung, C., Lee, T. G., Kim, J. H., Park, S. K., Yoo, J. S., Suh, P. G., Ryu, S. H. (1999) Biochemistry 38, 10344-10351). In our present study, a triple mutation of these phosphorylation sites diminished markedly phorbol 12-myristate 13-acetate (PMA)-induced PLD1 activity in COS-7 cells. We looked at the location of the PLD1 phosphorylation by PKC by observing PMA induced band shifts and by use of anti-phospho-PLD1 monoclonal antibody. The shifted PMA-induced proteins and the immunoreactivity of the anti-phospho-PLD1 antibody were mainly found in the caveolin-enriched membrane (CEM) fraction. Depletion of cellular cholesterol led to a loss of this compartmentalization of phosphorylated PLD1 in the CEM. Replacement of the cellular cholesterol led to the restoration of phosphorylated PLD1 in the CEM. Immunocytochemical studies of COS-7 cells revealed that PLD1 was localized in the plasma membrane as well as in the vesicular structures in the cytoplasm, but the phosphorylation of PLD1 occurred only in the plasma membrane. Our results, therefore, show that phosphorylation, and thereby activation, of PLD1 by PKC occurs in the caveolin and cholesterol-enriched low density domain of the plasma membrane in COS-7 cells.

Gram-negative bacteria-binding protein, a pattern recognition receptor for lipopolysaccharide and beta-1,3-glucan that mediates the signaling for the induction of innate immune genes in Drosophila melanogaster cells.

Pattern recognition receptors, non-clonal immune proteins recognizing common microbial components, are critical for non-self recognition and the subsequent induction of Rel/NF-kappaB-controlled innate immune genes. However, the molecular identities of such receptors are still obscure. Here, we present data showing that Drosophila possesses at least three cDNAs encoding members of the Gram-negative bacteria-binding protein (DGNBP) family, one of which, DGNBP-1, has been characterized. Western blot, flow cytometric, and confocal laser microscopic analyses demonstrate that DGNBP-1 exists in both a soluble and a glycosylphosphatidylinositol-anchored membrane form in culture medium supernatant and on Drosophila immunocompetent cells, respectively. DGNBP-1 has a high affinity to microbial immune elicitors such as lipopolysaccharide (LPS) and beta-1,3-glucan whereas no binding affinity is detected with peptidoglycan, beta-1,4-glucan, or chitin. Importantly, the overexpression of DGNBP-1 in Drosophila immunocompetent cells enhances LPS- and beta-1,3-glucan-induced innate immune gene (NF-kappaB-dependent antimicrobial peptide gene) expression, which can be specifically blocked by pretreatment with anti-DGNBP-1 antibody. These results suggest that DGNBP-1 functions as a pattern recognition receptor for LPS from Gram-negative bacteria and beta-1, 3-glucan from fungi and plays an important role in non-self recognition and the subsequent immune signal transmission for the induction of antimicrobial peptide genes in the Drosophila innate immune system.

Colonization rates and serotypes of group B streptococci isolated from pregnant women in a Korean tertiary hospital.

In a study designed to provide data on the rates of maternal carriage of group B streptococci (GBS) in Korean women, vaginal, anorectal, and urethral swab specimens from 459 pregnant women and ear canal and umbilicus swabs from their 288 neonates were cultured with new Granada medium and selective Todd-Hewitt broth. Additionally, the serotypes of 64 isolates of GBS and the minimal inhibitory concentrations of seven antimicrobial agents for these isolates were determined. The rate of colonization by GBS in pregnant women and in their babies was 5.9% (27/459) and 0.7% (2/288), respectively. The rates of resistance of GBS isolated from pregnant women were 13.3% to clindamycin, 5% to erythromycin, and 98.3% to tetracycline. The majority of GBS isolates from pregnant women belonged to serotypes Ib (48.3%), Ia (24.1%), and III (20.7%).

In vitro susceptibilities of the Bacteroides fragilis group to 14 antimicrobial agents in Korea.

The susceptibilities to 14 antimicrobial agents of 172 clinical isolates of the Bacteroides fragilis group from Korean patients during 1989 and 1990 were tested by an agar dilution method. All the isolates tested were susceptible to imipenem, chloramphenicol, and metronidazole. The rate of resistance to cefoxitin was 6%.