BLTR1 in Monocytes Emerges as a Therapeutic Target For Vascular Inflammation With a Subsequent Intimal Hyperplasia in a Murine Wire-Injured Femoral Artery

Given the importance of high-mobility group box 1 (HMGB1) and 5-lipoxygenase (5-LO) signaling in vascular inflammation, we investigated the role of leukotriene signaling in monocytes on monocyte-to-macrophage differentiation (MMD) induced by HMGB1, and on vascular inflammation and subsequent intimal hyperplasia in a mouse model of wire-injured femoral artery. In cultured primary bone marrow-derived cells (BMDCs) stimulated with HMGB1, the number of cells with macrophage-like morphology was markedly increased in association with an increased expression of CD11b/Mac-1, which were attenuated in cells pre-treated with Zileuton, a 5-LO inhibitor as well as in 5-LO-deficient BMDCs. Of various leukotriene receptor inhibitors examined, which included leukotriene B4 receptors (BLTRs) and cysteinyl leukotriene receptors (cysLTRs), the BLTR1 inhibitor (U75302) exclusively suppressed MMD induction by HMGB1. The importance of BLTR1 in HMGB1-induced MMD was also observed in BMDCs isolated from BLTR1-deficient mice and BMDCs transfected with BLTR1 siRNA. Although leukotriene B4 (LTB4) had minimal direct effects on MMD in control and 5-LO-deficient BMDCs, MMD attenuation by HMGB1 in 5-LO-deficient BMDCs was significantly reversed by exogenous LTB4, but not in BLTR1-deficient BMDCs, suggesting that LTB4/BLTR1-mediated priming of monocytes is a prerequisite of HMGB1-induced MMD. In vivo, both macrophage infiltration and intimal hyperplasia in our wire-injured femoral artery were markedly attenuated in BLTR1-deficient mice as compared with wild-type controls, but these effects were reversed in BLTR1-deficient mice transplanted with monocytes from control mice. These results suggest that BLTR1 in monocytes is a pivotal player in MMD with subsequent macrophage infiltration into neointima, leading to vascular remodeling after vascular injury.

PAF enhances MMP-2 production in rat aortic VSMCs via a β-arrestin2-dependent ERK signaling pathway

Platelet-activating factor (PAF), 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine, is a potent phospholipid mediator and has been reported to be localized in atherosclerotic plaque. However, its role in the progression of atherosclerosis remains unclear. In the present study, we investigated the role of PAF in the production of matrix metalloproteinase (MMP) in primary vascular smooth muscle cells (VSMCs). When rat aortic primary VSMCs were stimulated with PAF (1 nmol/l), the expressions of MMP-2 mRNA and protein, but not of MMP-9, were significantly increased, and these upregulations were markedly attenuated by inhibiting extracellular signal-regulated kinases (ERKs) using molecular and pharmacological inhibitors, but not by using inhibitors of p38 mitogen-activated protein kinase or c-Jun N-terminal kinase. Likewise, ERK phosphorylation was markedly enhanced in PAF-stimulated VSMCs, and this was attenuated by WEB2086, but not by EGF receptor inhibitor, demonstrating the specificity of PAF receptor (PAFR) in PAF-induced ERK phosphorylation. In immunofluorescence studies, β-arrestin2 in PAF-stimulated VSMCs colocalized with PAFR and phosphorylated ERK (P-ERK). Coimmunoprecipitation results suggest that β-arrestin2-bound PAFRs existed as a complex with P-ERK. In addition, PAF-induced ERK phosphorylation and MMP-2 production were significantly attenuated by β-arrestin2 depletion. Taken together, the study shows that PAF enhances MMP-2 production in VSMCs via a β-arrestin2-dependent ERK signaling pathway.

Selective activation of Akt1 by mammalian target of rapamycin complex 2 regulates cancer cell migration, invasion, and metastasis

Mammalian target of rapamycin complex (mTORC) regulates a variety of cellular responses including proliferation, growth, differentiation and cell migration. In this study, we show that mammalian target of rapamycin complex 2 (mTORC2) regulates invasive cancer cell migration through selective activation of Akt1. Insulin-like growth factor-1 (IGF-1)-induced SKOV-3 cell migration was completely abolished by phosphatidylinositol 3-kinase (PI3K) (LY294002, 10 μM) or Akt inhibitors (SH-5, 50 μM), whereas inhibition of extracellular-regulated kinase by an ERK inhibitor (PD98059, 10 μM) or inhibition of mammalian target of rapamycin complex 1 (mTORC1) by an mTORC1 inhibitor (Rapamycin, 100 nM) did not affect IGF-1-induced SKOV-3 cell migration. Inactivation of mTORC2 by silencing Rapamycin-insensitive companion of mTOR (Rictor), abolished IGF-1-induced SKOV-3 cell migration as well as activation of Akt. However, inactivation of mTORC1 by silencing of Raptor had no effect. Silencing of Akt1 but not Akt2 attenuated IGF-1-induced SKOV-3 cell migration. Rictor was preferentially associated with Akt1 rather than Akt2, and over-expression of Rictor facilitated IGF-1-induced Akt1 activation. Expression of PIP3-dependent Rac exchanger1 (P-Rex1), a Rac guanosine exchange factor and a component of the mTOR complex, strongly stimulated activation of Akt1. Furthermore, knockdown of P-Rex1 attenuated Akt activation as well as IGF-1-induced SKOV-3 cell migration. Silencing of Akt1 or P-Rex1 abolished IGF-1-induced SKOV-3 cell invasion. Finally, silencing of Akt1 blocked in vivo metastasis, whereas silencing of Akt2 did not. Given these results, we suggest that selective activation of Akt1 through mTORC2 and P-Rex1 regulates cancer cell migration, invasion and metastasis.

4-Hydroxynonenal enhances MMP-9 production in murine macrophages via 5-lipoxygenase-mediated activation of ERK and p38 MAPK

Exaggerated levels of 4-hydroxynonenal (HNE) and 5-lipoxygenase (5-LO) co-exist in macrophages in atherosclerotic lesions, and activated macrophages produce MMP-9 that degrades atherosclerotic plaque constituents. This study investigated the effects of HNE on MMP-9 production, and the potential role for 5-LO derivatives in MMP-9 production in murine macrophages. Stimulation of J774A.1 cells with HNE led to activation of 5-LO, as measured by leukotriene B(4) (LTB(4)) production. This was associated with an increased production of MMP-9, which was blunted by inhibition of 5-LO with MK886, a 5-LO inhibitor or with 5-LO siRNA. A cysteinyl-LT(1) (cysLT(1)) receptor antagonist, REV-5901 as well as a BLT(1) receptor antagonist, U-75302, also attenuated MMP-9 production induced by HNE. Furthermore, LTB(4) and cysLT (LTC(4) and LTD(4)) enhanced MMP-9 production in macrophages, suggesting a pivotal role for 5-LO in HNE-mediated production of MMP-9. Among the MAPK pathways, LTB(4) and cysLT enhanced phosphorylation of ERK and p38 MAPK, but not JNK. Linked to these results, a p38 MAPK inhibitor as well as an ERK inhibitor blunted MMP-9 production induced by LT. Collectively, these data suggest that 5-LO-derived LT mediates HNE-induced MMP-9 production via activation of ERK and p38 MAPK pathways, consequently leading to plaque instability in atherosclerosis.

Participation of 5-lipoxygenase-derived LTB(4) in 4-hydroxynonenal-enhanced MMP-2 production in vascular smooth muscle cells

5-Lipoxygenase (5-LO) has been suggested as a modulator of atherosclerotic plaque instability, however, its role in MMP production in vascular smooth muscle cells (VSMC) is still unclear. Thus, this study investigated the role of 5-LO in HNE-enhanced MMP-2 production in VSMC, and the mechanisms by which this enzyme could be activated by HNE. VSMC stimulated with HNE (1 microM) produced MMP-2, which was markedly attenuated in 5-LO-deficient VSMC as well as in cells pretreated with a FLAP inhibitor, MK886, confirming a role for 5-LO metabolites in HNE-enhanced MMP-2 production. Related to these results, HNE increased nuclear translocation of 5-LO promoting 5-LO activity, which was attenuated not only by SB203580, a p38 MAPK inhibitor, but also by PD98059, an ERK inhibitor. In parallel, phosphorylation of p38 MAPK and ERK occurred as early as 15 min after exposure to HNE, suggesting a potential role for p38 MAPK and ERK pathways in HNE-induced activation of 5-LO. Among leukotriene (LT) receptor antagonists, U-75302, a BLT receptor antagonist, but not MK-571 and Rev-5901, cysLT receptor antagonists, showed an inhibitory effect on HNE-enhanced MMP-2 production. Moreover, MMP-2 production in VSMC was also significantly increased by LTB(4), but not by LTC(4) and LTD(4). Collectively, these data suggest that 5-LO mediates HNE-enhanced MMP-2 production via LTB(4)-BLT receptor pathways, consequently leading to atherosclerotic plaque instability.

4-Hydroxynonenal enhances CD36 expression on murine macrophages via p38 MAPK-mediated activation of 5-lipoxygenase

Increased levels of 4-hydroxynonenal (HNE) and 5-lipoxygenase (5-LO) coexist in atherosclerotic lesions but their relationship in atherogenesis is unclear. This study investigated the role of 5-LO in HNE-induced CD36 expression and macrophage foam cell formation, and the link between HNE and 5-LO. In J774A.1 murine macrophages, HNE (10 microM) enhanced CD36 expression in association with an increased uptake of oxLDL, which was blunted by inhibition of 5-LO with MK886, a 5-LO inhibitor, or with 5-LO siRNA. In peritoneal macrophages from 5-LO-deficient mice, HNE-induced CD36 expression was markedly attenuated, confirming a pivotal role of 5-LO in HNE-induced CD36 expression. In an assay for 5-LO activity, stimulation of macrophages with HNE led to increased leukotriene B(4) production in the presence of exogenous arachidonic acid in association with an increased association of 5-LO to the nuclear membrane. Among the mitogen-activated protein kinase (MAPK) pathways involved in 5-LO phosphorylation, HNE predominantly activated p38 MAPK in macrophages, and the p38 MAPK inhibitor SB203580, but not an extracellular signal-regulated kinase inhibitor, suppressed HNE-induced LTB(4) production. Collectively, these data suggest that p38 MAPK-mediated activation of 5-LO by HNE might enhance CD36 expression, consequently leading to the formation of macrophage foam cells.

Akt2, but not Akt1, is required for cell survival by inhibiting activation of JNK and p38 after UV irradiation

The serine/threonine protein kinase, Akt/PKB, has an essential function in cell survival during response to various stresses. Recent studies have demonstrated that Akt isoforms exhibit some distinct physiological functions, but the isotype-specific functions for Akt in the stress response have not been fully identified. In this study, we analysed the cellular response to genotoxic stress using isogenic wild-type, Akt1(-/-) and Akt2(-/-) mouse embryonic fibroblasts (MEFs). Marked hypersensitivity of Akt2(-/-) MEFs was observed to UV irradiation, whereas wild-type and Akt1(-/-) MEFs showed comparable levels of resistance. Akt2(-/-) mouse aortic endothelial cells also showed hypersensitivity to UV and the reconstitution of Akt2 expression in the Akt2(-/-) MEFs restored the UV resistance of the cells. Interestingly, upon UV irradiation, JNK and p38 were significantly upregulated in Akt2(-/-) MEFs, compared to wild-type and Akt1(-/-) MEFs. Additionally, inhibition of JNK and p38 activation reduced UV-induced cell death. Furthermore, both the hyperactivation of JNK and p38 and the UV-induced cell death in Akt2(-/-) MEFs were completely inhibited by restoring Akt2 expression. These results indicate that Akt2, but not Akt1, is essential for cell survival upon UV irradiation, and that Akt2 prevents UV-induced cell death by inhibiting activation of JNK and p38.

4-Hydroxynonenal enhances MMP-2 production in vascular smooth muscle cells via mitochondrial ROS-mediated activation of the Akt/NF-kappaB signaling pathways

4-Hydroxynonenal (HNE) accumulates at atherosclerotic lesions, but its role in the progression of atherosclerosis is not clear. Considering the role of matrix metalloproteinases (MMP) in plaque destabilization, we investigated the mechanism by which HNE induces MMP production in vascular smooth muscle cells (VSMC). VSMC stimulated by HNE (1.0 microM) produced enzymatically active MMP-2 with an increased promoter activity, which was abolished by mutation of the NF-kappaB binding site in the promoter region. The increased NF-kappaB activity with subsequent MMP-2 production by HNE was significantly attenuated by transfection with Akt siRNA as well as by pretreatment with the PI3K/Akt inhibitors LY294002 (10 microM) and SH-5 (1.0 microM). The phosphorylation of Akt occurred as early as 5 min in VSMC exposed to HNE and was markedly attenuated by inhibition of mitochondrial reactive oxygen species (ROS). Furthermore, the impact of mitochondrial ROS on HNE-induced Akt phosphorylation with subsequent MMP-2 production was also demonstrated in mitochondrial function-deficient VSMC, as well as in cells transfected with manganese superoxide dismutase. Taken together, these results suggest that HNE enhances MMP-2 production in VSMC via mitochondrial ROS-mediated activation of the Akt/NF-kappaB signaling pathways.

4-hydroxynonenal contributes to macrophage foam cell formation through increased expression of class A scavenger receptor at the level of translation

4-Hydroxynonenal (HNE) is known to be atherogenic, but its mechanism of action in atherogenesis is not clear. Therefore, this study investigated the role of HNE in macrophage foam cell formation and the underlying mechanism involved in HNE-induced expression of scavenger receptors (SRs). In the aortic sinus of ApoE-deficient mice fed a high-fat diet, multiple plaque lesions were accompanied by increased accumulation of HNE adducts in the enhanced Mac-2 stained area. In an in vitro study, HNE exposure to J774A.1 macrophages led to increased expression of class A SR (SR-A) and CD36 at the protein level with a concomitant increase in endocytic uptake of oxLDL. In contrast to CD36 protein expression, which was associated with an increase in mRNA expression, the HNE-enhanced SR-A protein expression was neither accompanied by its mRNA expression nor affected by actinomycin D. HNE enhanced the incorporation rates of (35)S-Met/Cys into SR-A, and HNE-induced SR-A protein expression was effectively attenuated by translation inhibitors such as cycloheximide and rapamycin. Taken together, these data suggest that HNE contributes to macrophage foam cell formation through increased synthesis of SR-A at the level of mRNA translation, consequently leading to the progression of atherosclerosis.

Cloning, expression, and characterization of a methionyl aminopeptidase from a hyperthermophilic archaeon Thermococcus sp. NA1

Genomic analysis of a hyperthermophilic archaeon Thermococcus sp. NA1 revealed the presence of an 885-bp open reading frame encoding a protein of 295 amino acids with a calculated molecular mass of 32,981 Da. Analysis of the deduced amino acid sequence showed that amino acid residues important for catalytic activity and the metal binding ligands conserved in all of methionyl aminopeptidases (MetAP) were also conserved and belonged to type IIa MetAP. The protein, designated TNA1_MetAP (Thermococcus sp. NA1 MetAP), was cloned and expressed in Escherichia coli. The recombinant enzyme was a Mn(2+)-, Ni(2+)-, Fe(2+)-, or Co(2+)-dependent metallopeptidase. Optimal MetAP activity against L: -methionine p-nitroanilide (Met-pNA) (K (m) = 0.68 mM) occurred at pH 7.0 and 80 to 90 degrees C. The MetAP was very unstable compared to Pyrococcus furiosus MetAP, which was completely inactivated by heating at 80 degrees C for 5 min. It seemed likely that the cysteine residue (Cys53) played a critical role in regulating the thermostability of TNA1_MetAP.

Genotypic prevalence of the fimbrial adhesins (F4, F5, F6, F41 and F18) and toxins (LT, STa, STb and STx2e) in Escherichia coli isolated from postweaning pigs with diarrhoea or oedema disease in Korea

A PCR was used to determine the genotypic prevalence of five fimbrial adhesins (F4, F5, F6, F41 and F18), two heat-stable enterotoxins (STa and STb), the heat-labile enterotoxin (LT), and the shiga toxin 2e (Stx2e) in 230 isolates of Escherichia coli from postweaning pigs with diarrhoea or oedema disease. Ninety-four (40.9 per cent) of the isolates carried genes for at least one of the fimbrial adhesins or toxins. Genes for the F18 fimbrial adhesin were detected in 18.3 per cent, and genes for F4, F6, F5 and F41 were detected in 10.0 per cent, 4.3 per cent, 1.7 per cent and 0.8 per cent of the isolates, respectively. Genes for STa, STb and LT were detected in 25.7 per cent, 15.2 per cent and 8.7 per cent of the isolates, respectively. Genes for Stx2e were detected in 36 (15.6 per cent) of the isolates, and among them 24 also contained the gene for F18ab and four also contained the gene for F18ac.

Caspase-mediated cleavage of TRAF3 in FasL-stimulated Jurkat-T cells

The tumor necrosis factor receptor (TNFR)-associated factor (TRAF) proteins play a central role in the early steps of signal transduction by TNFR superfamily proteins, which induce various cellular responses, including apoptosis. Influences of TRAF proteins on the regulation of cell death and physical interactions between TRAFs and caspases have been reported. In this study, we demonstrate that TRAF3 is proteolyzed during cell death in a caspase-dependent manner. TRAF3 was found to be cleaved by incubation with caspase3 in vitro and by Fas- or CD3-triggering in Jurkat-T cells. The Fas- or CD3-induced cleavage of TRAF3 was blocked by caspase inhibitors and by introduction of alanine substitutions for D347 and D367 residues. Furthermore, the amino-terminal fragment of TRAF3 showed a different intracellular localization from the full-length TRAF3 with preferential distribution to particulate fractions and the nucleus. These findings suggest that TRAF3 may be regulated by caspases during apoptosis of T cells.

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.

Proteolytic cleavage of epidermal growth factor receptor by caspases

Apoptotic proteases cleave and inactivate survival signaling molecules such as Akt/PKB, phospholipase C (PLC)-gamma1, and Bcl-2. We have found that treatment of A431 cells with tumor necrosis factor-alpha in the presence of cycloheximide resulted in the cleavage of epidermal growth factor receptor (EGFR) as well as the activation of caspase-3. Among various caspases, caspase-1, caspase-3 and caspase-7 were most potent in the cleavage of EGFR in vitro. Proteolytic cleavage of EGFR was inhibited by both YVAD-cmk and DEVD-fmk in vitro. We also investigated the effect of caspase-dependent cleavage of EGFR upon the mediation of signals to downstream signaling molecules such as PLC-gamma1. Cleavage of EGFR by caspase-3 significantly impaired the tyrosine phosphorylation of PLC-gamma1 in vitro. Given these results, we suggest that apoptotic protease specifically cleaves and inactivates EGFR, which plays crucial roles in anti-apoptotic signaling, to abrogate the activation of EGFR-dependent downstream survival signaling molecules.

2,2',4,6,6'-pentachlorobiphenyl induces apoptosis in human monocytic cells

Polychlorinatedbiphenyls (PCBs) are a group of persistent and widely dispersed environmental pollutants, some of which may be immunotoxic. In the present study, we investigated the effect of PCBs on immune system by assessing apoptotic cell death in human monocytic U937 cells. Among the various congeners tested, 2,2',4,6, 6'-pentachlorobiphenyl (PeCB), a highly ortho-substituted congener, specifically induced DNA fragmentation, a hallmark of apoptosis, while the other examined di-, tri-, tetra-, and pentachlorobiphenyls did not. To further study the 2,2',4,6,6'-PeCB-induced cell death, various features of apoptosis were examined. 2,2',4,6,6'-PeCB caused a decrease in cell viability and induced cellular morphologic features characteristic of apoptosis such as chromatin aggregation and apoptotic bodies. In addition, caspase-3, an executioner of apoptosis, was activated and its substrate, poly(ADP-ribose) polymerase (PARP), was cleaved during 2,2',4,6,6'-PeCB-induced apoptosis. In contrast, 3,3',4,4',5-PeCB, a congener of coplanar structure, as well as 2,3,7,8-TCDD did not induce apoptosis in these human monocytic cells, although they potently induced CYP 1A1 in human hepatoma Hep G2 cells. Taken together, the data indicate that 2,2',4,6,6'-PeCB induces apoptosis in human monocytic cells through a mechanism that is independent of the arylhydrocarbon receptor. This suggests a possibly separate mechanism by which PCBs cause immunosuppression.

Interleukin-6-induced tyrosine phosphorylation of phospholipase C-gamma1 in PC12 cells

Phospholipase C (PLC)-gamma1 plays a pivotal role in the signal transduction pathway mediated by growth factors. In this study, we found that neurite outgrowth of pheochromocytoma (PC12) cells was significantly induced by interleukin-6 (IL-6). Stimulation of PC12 cells with IL-6 led to tyrosine phosphorylation of PLC-gamma1 in a dose- and time-dependent manner. IL-6 stimulation also increased the hydrolysis of phosphatidylinositol 4,5-bisphosphate. Accumulation of total inositol phosphate as well as tyrosine phosphorylation of PLC-gamma1 was inhibited by the pretreatment of protein kinase inhibitors such as genistein and staurosporine. These results suggest that PLC-gamma1 may be involved in the signal transduction pathway of IL-6-induced PC12 cell differentiation.

Proteolytic cleavage of phospholipase C-gamma1 during apoptosis in Molt-4 cells

Apoptosis is a cell suicide mechanism that requires the activation of cellular death proteases for its induction. We examined whether the progress of apoptosis involves cleavage of phospholipase C-gamma1 (PLC-gamma1), which plays a pivotal role in mitogenic signaling pathway. Pretreatment of T leukemic Molt-4 cells with PLC inhibitors such as U-73122 or ET-18-OCH(3) potentiated etoposide-induced apoptosis in these cells. PLC-gamma1 was fragmented when Molt-4 cells were treated with several apoptotic stimuli such as etoposide, ceramides, and tumor necrosis factor alpha. Cleavage of PLC-gamma1 was blocked by overexpression of Bcl-2 and by specific inhibitors of caspases such as Z-DEVD-CH(2)F and YVAD-cmk. Purified caspase-3 and caspase-7, group II caspases, cleaved PLC-gamma1 in vitro and generated a cleavage product of the same size as that observed in vivo, suggesting that PLC-gamma1 is cleaved by group II caspases in vivo. From point mutagenesis studies, Ala-Glu-Pro-Asp(770) was identified to be a cleavage site within PLC-gamma1. Epidermal growth factor receptor (EGFR) -induced tyrosine phosphorylation of PLC-gamma1 resulted in resistance to cleavage by caspase-3 in vitro. Furthermore, cleaved PLC-gamma1 could not be tyrosine-phosphorylated by EGFR in vitro. In addition, tyrosine-phosphorylated PLC-gamma1 was not significantly cleaved during etoposide-induced apoptosis in Molt-4 cells. This suggests that the growth factor-induced tyrosine phosphorylation may suppress apoptosis-induced fragmentation of PLC-gamma1. We provide evidence for the biochemical relationship between PLC-gamma1-mediated signal pathway and apoptotic signal pathway, indicating that the defect of PLC-gamma1-mediated signaling pathway can facilitate an apoptotic progression.

Structural characteristics of low-molecular-mass displacers for cation-exchange chromatography. II. Role of the stationary phase

The relative efficacy of a variety of low-molecular-mass displacers was examined on three different stationary phase materials. Several homologous series of displacer molecules were evaluated on these ion-exchange resins using a displacer ranking plot based on the steric mass action model. The results demonstrate that while aromaticity and hydrophobicity can play a significant role in the affinity of displacer molecules on polymethacrylate based and hydrophilized polystyrene-divinylbenzene based materials, this effect is much less pronounced on an agarose based resin. The work presented in this paper demonstrates that different structural features of low-molecular-mass displacers can dominate their affinity on various stationary phase materials employed and provides rules of thumb for the design of high affinity, low-molecular-mass displacers for a variety of commercial cation-exchange materials.

Psoriasiform eruption triggered by recombinant granulocyte-macrophage colony stimulating factor (rGM-CSF) and exacerbated by granulocyte colony stimulating factor (rG-CSF) in a patient with breast cancer

Colony-stimulating factors (CSFs) are commonly used for the treatment of neutropenia following chemotherapy and for the mobilization of peripheral blood stem cells (PBSC). We recently experienced a rare case of a new onset of psoriasiform eruption by GM-CSF (granulocyte-macrophage colony-stimulating factor) which was exacerbated by G-CSF (granulocyte colony-stimulating factor) in a patient with breast cancer. A 36-year-old woman had received neoadjuvant chemotherapy (cyclophosphamide, epirubicin and 5-fluorouracil), modified radical mastectomy and adjuvant chemotherapy with paclitaxel and mitoxantrone followed by GM-CSF administration for the treatment of locally advanced breast cancer. She had developed a psoriatic skin lesion on face and both upper arms during leukocyte recovery in spite of no previous history of psoriasis. Next, the chemotherapy course was complicated by a flare of mild psoriatic skin lesion, although CSF was changed into G-CSF due to GM-CSF-associated psoriasis. Subsequently, she had had high-dose chemotherapy and autologous peripheral blood stem cell transplantation for consolidation therapy. GM-CSF was administered for the mobilization of PBSC and post-transplant period, but psoriatic skin lesion did not appear. During 6 months after PBSCT, psoriasiform eruption did not appear.

Structural characteristics of low-molecular-mass displacers for cation-exchange chromatography

The relative efficacy of a variety of low-molecular-mass displacers was examined using a displacer ranking plot. This method enables an evaluation of the dynamic affinity of a variety of displacers over a range of operating conditions. Several homologous series of molecules were evaluated to provide insight into the effects of various structural features on displacer efficacy. The results indicate that linear flexible geometries may have advantages over branched or cyclic structures. Data also indicate that the spreading out of charges may increase affinity. The incorporation of aromatic moieties in these displacers, particularly near the surface of the molecules, appears to result in a dramatic increase in displacer affinity. The ability of several high-affinity low-molecular-mass displacers a very strongly bound cationic protein is also examined. The results confirm the predictions of the theory and indicate that it is indeed possible to displace highly bound macromolecules with low-molecular-mass dispatchers. The work presented in this paper indicates that non-specific interactions can be exploited for producing high-affinity low-molecular-mass displacers.

Src homology domains of phospholipase C gamma1 inhibit nerve growth factor-induced differentiation of PC12 cells

Phospholipase C gamma1 (PLC-gamma1) is phosphorylated on treatment of cells with nerve growth factor (NGF). To assess the role of PLC-gamma1 in mediating the neuronal differentiation induced by NGF treatment, we established PC12 cells that overexpress whole PLC-gamma (PLC-gamma1PC12), the SH2-SH2-SH3 domain (PLC-gamma1SH223PC12), SH2-SH2-deleted mutants (PLC-gamma1deltaSH22PC12), and SH3-deleted mutants (PLC-gamma1deltaSH3PC12). Overexpressed whole PLC-gamma1 or the SH2-SH2-SH3 domain of PLC-gamma1 stimulated cell growth and inhibited NGF-induced neurite outgrowth of PC12 cells. However, cells expressing PLC-gamma1 lacking the SH2-SH2 domain or the SH3 domain had no effect on NGF-induced neuronal differentiation. Overexpression of intact PLC-gamma1 resulted in a threefold increase in total inositol phosphate accumulation on treatment with NGF. However, overexpression of the SH2-SH2-SH3 domain of PLC-gamma1 did not alter total inositol phosphate accumulation. To investigate whether the SH2-SH2-SH3 domain of PLC-gamma1 can mediate the NGF-induced signal, tyrosine phosphorylation of the SH2-SH2-SH3 domain of PLC-gamma1 on NGF treatment was examined. The SH2-SH2-SH3 domain of PLC-gamma1 as well as intact PLC-gamma1 could be tyrosine-phosphorylated on NGF treatment. These results indicate that the overexpressed SH2-SH2-SH3 domain of PLC-gamma1 can block the differentiation of PC12 cells induced by NGF and that the inhibition appears not to be related to the lipase activity of PLC-gamma1 but to the SH2-SH2-SH3 domain of PLC-gamma1.

Purification and characterization of the 2-ketoaldonate reductase from Brevibacterium ketosoreductum ATCC21914

2-Ketoaldonate reductase, which is involved in ketogluconate catabolism, was purified to homogeneity from Brevibacterium ketosoreductum ATCC21914. The enzyme was found to catalyze the reduction of 2,5-diketo-D-gluconate to 5-keto-D-gluconate, and to a lesser extent, 2-keto-D-gluconate to D-gluconate, and 2-keto-L-gluconate to L-idonate. The molecular mass of the reductase was 35 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 72 kDa by gel filtration, indicating that the native enzyme may exist as a dimer. The reductase was optimally active at pH 6.0 with NADPH as a preferred electron donor. The pI of 4.7 was measured for the enzyme. The apparent Km for 2,5-diketo-D-gluconate and NADPH were 5 microM and 10 microM, respectively. The amino-terminal amino acid sequence was NH2-Ala-Ser-Ile-Ser-Val-Ser-Val-Pro-Ser-Ala- Arg-Leu-Ala-Glu-Asp-Leu-Ser-Asp-Ile-Glu.

Identification and partial characterization of tochicin, a bacteriocin offduced by Bacillus thuringiensis subsp tochigiensis

Bacillus thuringiensis subsp tochigiensis HD868 was identified as a bacteriocin producer which exhibited a bactericidal effect against closely related species. This bacteriocin designated as tochicin, was partially purified by 75% ammonium sulfate precipitation followed by subsequent dialysis. This partially purified tochicin showed a narrow antibacterial spectrum of activity against most of 20 typical B. thuringiensis strains and a strain of B. cereus, but not against other bacteria and yeasts tested. The antibacterial activity of tochicin on sensitive indicator cells disappeared completely by proteinase K treatment (1 mg ml-1), which indicates its proteinaceous nature. Tochicin was very stable throughout the range of pH 3.0-9.0 and was relatively heat-stable at 90 degrees C, but bacteriocin activity was not detected after boiling for 30 min. The relationship between cell growth and bacteriocin production was studied in a semi-defined medium. Tochicin activity was detected at the mid-log growth phase, reached the maximum at the early stationary phase, but decreased after the stationary phase. Direct detection of tochicin activity on sodium dodecyl sulfate-polyacrylamide gel suggested it has an apparent molecular mass of about 10.5 kDa. Tochicin exhibited a bactericidal activity against B. thuringiensis subsp thompsoni HD522 in phosphate buffer (pH 7.0).

Inhibition of phospholipase D by a protein factor from bovine brain cytosol. Partial purification and characterization of the inhibition mechanism

A specific protein inhibitor of partially purified bovine brain phospholipase D (PLD) was identified from bovine brain cytosol. The PLD inhibitor has been enriched through several chromatographic steps and characterized with respect to size and mechanism of inhibition. The inhibitor showed an apparent molecular mass of 30 kDa by Superose 12 gel exclusion chromatography and inhibited PLD activity with an IC50 of 7 nM. The inhibitor had neither proteolytic activity nor phospholipid-hydrolyzing activity. Because phosphatidylinositol 4,5-bisphosphate (PIP2), which is included in substrate vesicles, is an essential cofactor for PLD, we examined whether the inhibition might be mediated by sequestration of PIP2. PIP2 hydrolysis by phospholipase C (PLC)-beta1 was not affected by the inhibitor and the inhibitor did not bind to substrate vesicles containing PIP2. In contrast, a PH domain derived from PLC-delta1, which could bind to PIP2, showed a nearly identical inhibition of both PLC-beta1 and PLD activities. Thus, the PLD inhibition by the inhibitor is due to the specific interaction with not PIP2 but PLD. The suppression of PLD activity by the inhibitor was largely eliminated by the addition of ADP-ribosylation factor (ARF) and GTPgammaS. We propose that the inhibitor plays a negative role in regulation of PLD activity by PIP2 and ARF.