Chemokine-independent preference for T-helper-1 cells in transendothelial migration

We analyzed differences in the transendothelial migration (TEM) ability of T-helper (Th)-1 and Th2 cells across a murine endothelial cell line (F-2) under static conditions. The TEM abilities of Th1 cells from mice bearing autoimmune diseases and antigen-specific Th1 cell lines were severalfold higher than those of Th2 cells and lines of the same origin. These preferences were observed without exogenous chemoattractant and were insensitive to pertussis toxin, which completely blocks TEM induced by exogenous chemoattractants. Antibodies against LFA-1 and ICAM-1 as well as CD44 markedly blocked the TEM of Th1 cells. TEM ability was also blocked by pharmacological inhibitors of Src family protein-tyrosine kinases (PP2 and herbimycin A), phosphatidylinositol 3-kinase (wortmannin), and phosphatidylinositol-specific phospholipase C (). Cross-linking of CD44 strongly induced highly elongated morphology in Th1 lines, but weakly in Th2 lines. The pharmacological inhibitors that blocked TEM also inhibited this morphological change, whereas pertussis toxin did not. These data indicate that there are signaling pathways for TEM independent of chemokine attraction, but through adhesion molecules including CD44, and that the preferential TEM ability of Th1 over Th2 cells is formed, at least in part, by intrinsic differences in these pathways.     

Entomogenous fungus Nomuraea rileyi inhibits host insect molting by C22-oxidizing inactivation of hemolymph ecdysteroids

The entomogenous fungus Nomuraea rileyi reportedly secretes a proteinaceous substance inhibiting larval molt and metamorphosis in the silkworm Bombyx mori. We studied the possibility that N. rileyi controls B. mori development by inactivating hemolymph molting hormone, ecdysteroids. Incubation of ecdysone (E) and 20-hydroxyecdysone (20E) in fungal-conditioned medium resulted in their rapid modification into products with longer retention times in reverse-phase HPLC. Each modified product from E and 20E was purified by HPLC, and identified by NMR as 22-dehydroecdysone and 22-dehydro-20-hydroxyecdysone. Some other ecdysteroids with a hydroxyl group at position C22 were also modified. Injection of the fungal-conditioned medium into Bombyx mori larvae in the mid-4th instar inhibited larval molt but induced precocious pupal metamorphosis, and its injection into 5th instar larvae just after gut purge blocked pupal metamorphosis. In hemolymph of injected larvae, E and 20E disappeared and, in turn, 22-dehydroecdysone and 22-dehydro-20-hydroxyecdysone accumulated. These results indicate that N. rileyi secretes a specific enzyme that oxidizes the hydroxyl group at position C22 of hemolymph ecdysteroids and prevents molting in B. mori larvae.     

Similarity of tetracycline resistance genes isolated from fish farm bacteria to those from clinical isolates

Tetracycline-resistant (Tet(r)) bacteria were isolated from fishes collected at three different fish farms in the southern part of Japan in August and September 2000. Of the 66 Tet(r) gram-negative strains, 29 were identified as carrying tetB only. Four carried tetY, and another four carried tetD. Three strains carried tetC, two strains carried tetB and tetY, and one strain carried tetC and tetG. Sequence analyses indicated the identity in Tet(r) genes between the fish farm bacteria and clinical bacteria: 99.3 to 99.9% for tetB, 98.2 to 100% for tetC, 99.7 to 100% for tetD, 92.0 to 96.2% for tetG, and 97.1 to 100% for tetY. Eleven of the Tet(r) strains transferred Tet(r) genes by conjugation to Escherichia coli HB-101. All transconjugants were resistant to tetracycline, oxycycline, doxycycline, and minocycline. The donors included strains of Photobacterium, Vibrio, Pseudomonas, Alteromonas, Citrobacter, and Salmonella spp., and they transferred tetB, tetY, or tetD to the recipients. Because NaCl enhanced their growth, these Tet(r) strains, except for the Pseudomonas, Citrobacter, and Salmonella strains, were recognized as marine bacteria. Our results suggest that tet genes from fish farm bacteria have the same origins as those from clinical strains.     

Expression and characterization of human bifunctional peptidylglycine alpha-amidating monooxygenase

We report the purification and characterization of human bifunctional peptidylglycine alpha-amidating monooxygenase (the bifunctional PAM) expressed in Chinese hamster ovary cells. PAM is in charge of the formation of the C-terminal amides of biologically active peptides. The bifunctional PAM possesses two catalytic domains in a single polypeptide, peptidylglycine alpha-hydroxylating monooxygenase (PHM, EC 1.14.17.3) and peptidylamidoglycolate lyase (PAL, EC 4.3.2.5). By introducing a stop codon at 835 Glu, we were able to eliminate the membrane-spanning domain in the C-terminal region and succeeded in purifying a soluble form of bifunctional PAM that was secreted into the medium. Through a three-step purification procedure, we obtained 0.3mg of the purified PAM, which showed a single band at 91 kDa on SDS-PAGE, from 1L of monolayer culture medium. Metals contained in the purified PAM were analyzed and chemical modifications were performed to gain insight into the mechanism of the PAL reaction. Inductively coupled plasma detected 0.62 mol of Zn(2+) and 1.25 mol of Cu(2+) per mol of bifunctional PAM. Further, the addition of 1mM EDTA reduced the PAL activity by about 50%, but the decreased activity was recovered by the addition of an excess amount of Zn(2+). In a series of chemical modifications, phenylglyoxal almost completely eliminated the PAL activity and diethyl pyrocarbonate suppressed activity by more than 70%. These findings implied that Arg and His residues might play crucial roles during catalysis.     

A root-specific O-methyltransferase gene expressed in salt-tolerant barley

A cDNA encoding an O-methyltransferase (OMT) was isolated from salt-tolerant barley roots by subtraction hybridization with cDNAs of salt-tolerant barley roots as a tester cDNA and cDNAs of the salt-sensitive barley roots as a driver cDNA. The deduced amino acid sequence showed significant identity with plant caffeic acid/5-hydroxyferulic acid OMTs. Southern blot analysis showed that the OMT gene was a single copy in both salt-tolerant and -sensitive barley. The cloned gene was expressed in a wheat germ cell-free system to produce the OMT, which had methylating activity for caffeic acid. Northern blot analysis showed that the OMT gene was expressed constitutively in the salt-tolerant barley roots and the expression level was increased 1.5 times by salt stress, but the salt-sensitive barley showed no expression of the gene in roots and leaves.     

Random multi-recombinant PCR for the construction of combinatorial protein libraries

Development of a new methodology to create protein libraries, which enable the exploration of global protein space, is an exciting challenge. In this study we have developed random multi-recombinant PCR (RM-PCR), which permits the shuffling of several DNA fragments without homologous sequences. In order to evaluate this methodology, we applied it to create two different combinatorial DNA libraries. For the construction of a ‘random shuffling library’, RM-PCR was used to shuffle six DNA fragments each encoding 25 amino acids; this affords many different fragment sequences whose every position has an equal probability to encode any of the six blocks. For the construction of the ‘alternative splicing library’, RM-PCR was used to perform different alternative splicings at the DNA level, which also yields different block sequences. DNA sequencing of the RM-PCR products in both libraries revealed that most of the sequences were quite different, and had a long open reading frame without a frame shift or stop codon. Furthermore, no distinct bias among blocks was observed. Here we describe how to use RM-PCR for the construction of combinatorial DNA libraries, which encode protein libraries that would be suitable for selection experiments in the global protein space.     

Characterization and distribution of a new enterotoxin-related superantigen produced by Staphylococcus aureus

Staphylococcal enterotoxins (SEs) are a family of structurally related pyrogenic exotoxins consisting of the five prototypic SEs (types A to E) and three newly characterized SEs (types G to I) produced by Staphylococcus aureus (S. aureus). They also work as superantigens and cause food poisoning and shock symptoms in humans. In this study, we cloned a new variant gene of the seg and characterized its superantigenic properties and distribution among the clinical isolates of S. aureus. The gene encodes a 233 amino acid protein which is highly homologous to SEG (97.7%). The variant SEG (SEGv) expressed by the cloned gene exerted mitogenic activity on human peripheral blood mononuclear cells at the concentration of 100 pg/ml. T cells bearing Vbeta3, 12, 13.1, 13.2, 14 and 15 were preferentially expanded after stimulation with the recombinant protein. The mRNA of the variant seg gene was detected in the total RNA of the organisms bearing this gene. By PCR, 27 out of 48 clinical isolates of S. aureus (56%) possessed either the seg or variant seg gene. These findings suggest that SEG, or SEGv, is one of the most frequently produced superantigen exotoxins by S. aureus and may participate in the inflammatory process of the host by activating a distinct set of Vbeta families of T cells.     

LSD1 Overexpression Is Associated with Poor Prognosis in Basal-Like Breast Cancer,and Sensitivity to PARP Inhibition

LSD1, a lysine-specific histone demethylase, is overexpressed in several types of cancers and linked to poor outcomes. In breast cancer, the significance of LSD1 overexpression is not clear. We have performed an in silico analysis to assess the relationship of LSD1 expression to clinical outcome. We demonstrate that LSD1 overexpression is a poor prognostic factor in breast cancer, especially in basal-like breast cancer, a subtype of breast cancer with aggressive clinical features. This link is also observed in samples of triple negative breast cancer. Interestingly, we note that overexpression of LSD1 correlates with down-regulation of BRCA1 in triple negative breast cancer. This phenomenon is also observed in in vitro models of basal-like breast cancer, and is associated with an increased sensitivity to PARP inhibitors. We propose therefore that high expression levels of the demethylase LSD1 is a potential prognostic factor of poor outcome in basal-like breast cancer, and that PARP inhibition may be a therapeutic strategy of interest in this poor prognostic subtype with overexpression of LSD1.