Binding of laminin-1 to monosialoganglioside GM1 in lipid rafts is crucial for neurite outgrowth

Laminin-1, an extracellular matrix molecule, promotes neurite outgrowth through the interaction of integrin and actin. Monosialoganglioside GM1 in the lipid rafts associates with and activates the NGF receptor TrkA, and enhances neurite outgrowth. However, the role of GM1 in laminin-1-induced neurite outgrowth was still unclear. Here, we describe that laminin-1 binds to GM1 through a carbohydrate moiety and a specific conformation of GM1, induces focal formation of large clusters of GM1, and enhances the relocation of TrkA in the membrane of dorsal root ganglion (DRG) and PC12 cells. We found that laminin-1-mediated clustering of GM1 causes the translocation and enrichment of beta1 integrin in lipid rafts--where TrkA colocalizes with beta1 integrin--and the activation of Lyn, Akt and MAPK to promote the outgrowth of neurites. Our results suggest that the binding of laminin-1 to GM1 facilitates the formation of a focal microdomain in the membrane, and enhances signal transduction that promotes neurite outgrowth by linking NGF-TrkA signaling with the laminin-integrin signaling pathways.

Expansion of CD4+CD28- T cells producing high levels of interferon-{gamma} in peripheral blood of patients with multiple sclerosis

CD4(+) T cells that lack surface expression of the CD28 co-stimulatory molecule (CD4(+)CD28(-) T cells) were expanded in peripheral blood of patients with multiple sclerosis (MS) [5.20 +/- 1.67% vs 13.00 +/- 2.68% (healthy controls (HC) versus patients with MS)]. Both the CD4(+)CD28(+) and CD4(+)CD28(-) T-cell populations of patients with MS produced higher levels of interferon (IFN)-gamma compared with those in HC. In particular, the proportion of IFN-gamma(+) cells among CD4(+)CD28(-) T cells from patients with MS was considerably high. However, expression of co-stimulatory molecules including inducible costimulator (ICOS), activating natural killer receptors, or members of tumor necrosis factor receptor family that replace CD28 in CD4(+)CD28(-) T cells of patients with MS could not be identified. A unique subpopulation bearing the CD45RA(high)CCR7(-) phenotype was identified among the CD4(+)CD28(-) T cells of some patients with MS. Because only MS samples contained this CD45RA(high)CCR7(-) population attributed to terminally differentiated effector memory cells and lacked naive CD45RA(high)CCR7(+) cells, we suggest that CD4(+)CD28(-) T cells of patients with MS represent a cell population which is in more differentiated state than healthy subjects. In patients treated with IFN-beta-1b, IFN-gamma production from CD4(+)CD28(+) T cells was suppressed compared with that in untreated patients. On the contrary, in the CD4(+)CD28(-) population, production of IFN-gamma in IFN-beta-1b-treated patients was not significantly suppressed compared with that in untreated patients with MS. Thus, an additional treatment strategy that specifically targets this cell population may enhance the beneficial effect of IFN-beta on MS.

Protein biomarker analysis by mass spectrometry in patients with rheumatoid arthritis receiving anti-tumor necrosis factor-alpha antibody therapy

OBJECTIVE

To investigate the mechanism of action of anti-tumor necrosis factor-alpha (TNF-alpha) antibody in patients with rheumatoid arthritis (RA), we analyzed serum or plasma proteins by mass spectrometry system.

METHODS

Ten RA patients who received treatment with anti-TNF-alpha antibody were studied. Samples obtained before and after therapy were analyzed by a two-dimensional liquid chromatography tandem mass spectrometry (2D LC-MS/MS) system after pretreatment by a recently developed method to remove high molecular weight proteins.

RESULTS

Using this system, certain proteins were identified after treatment with anti-TNF-alpha antibody, including proteins related to the TNF-alpha-mediated pathway for nuclear factor kappa B (NF-kappaB) activation and/or to the metabolism (including regeneration) of articular cartilage.

CONCLUSION

Our mass spectrometry system appears to be useful for proteomic analysis. The efficacy of anti-TNF-alpha antibody therapy for RA may be related to various consequence of the inhibition of TNF-alpha activity.

Effect of high fat diet on NKT cell function and NKT cell-mediated regulation of Th1 responses

Diet is one of the important factors that modulate immune responses. In the present study, we have examined the capacity of dietary lipids to modify immune responses in mice and we have investigated the contribution of glycolipid-reactive natural killer T (NKT) cells in this process. Mice fed, high fat diet (HFD; 21.2% fat, 0.20% cholesterol) for 3 weeks, as compared with mice fed standard fat diet (SFD; 4.3% fat, 0.03% cholesterol), showed significantly reduced interferon-gamma production in sera at 6 or 12 h after intraperitoneal injection of an NKT cell ligand, alpha-galactosylceramide. In contrast, production of interleukin-13 was significantly higher at 2 and 6 h in HFD fed mice compared with mice on SFD. No difference was detected in the serum interleukin-4 levels between these two groups of animals. The proportion of NKT cells in spleen and liver was reduced in mice fed HFD compared with those on SFD. In addition, activation of NKT cells assessed by up-regulation of CD69 was suppressed specifically in liver from mice fed HFD. Recall responses of conventional T cells and delayed-type hypersensitivity (Th1 type) against ovalbumin were significantly suppressed in mice fed HFD in comparison with those fed SFD. This suppression was not observed in CD1d-/- mice, suggesting that NKT cells in mice fed HFD played a role in suppressing Th1 responses. Taken together, our findings suggest a critical link between NKT cells, dietary lipid and adaptive immune responses.

2-Methoxyestradiol reduces monocyte adhesion to aortic endothelial cells in ovariectomized rats

2-Methoxyestradiol (2-ME) is an endogenous metabolite of estradiol with no affinity for estrogen receptors. It inhibits cell proliferation, thus is a potentially useful drug to block the progression of atherosclerosis. As a first step to examining the anti-atherosclerotic effects of 2-ME, we investigated monocyte adhesion to aortic endothelial cells, which is considered a prerequisite to atherosclerosis in vivo. Eight-week-old Sprague-Dawley rats were ovariectomized then treated by slow-release pellets with placebo, 17-beta-estradiol (5 microg/day), low-dose 2-ME (10 microg/day), or high-dose 2-ME (100 microg/day). After 6 weeks, en face analysis showed an increased number of monocytes adhering to endothelial cells of the thoracic aorta in ovariectomized rats compared with sham-operated controls. This increase was predominantly inhibited by treatment with 17beta-estradiol, and low-dose or high-dose 2-ME. The observed effects were unrelated to changes in serum lipids, blood glucose, or blood pressure. Our data suggested that 2-ME mediates the anti-atherosclerotic actions of estradiol at least in part by preventing monocyte adhesion to the aortic endothelium.

Involvement of very long fatty acid-containing lactosylceramide in lactosylceramide-mediated superoxide generation and migration in neutrophils

The neutral glycosphingolipid lactosylceramide (LacCer) forms lipid rafts (membrane microdomains) coupled with the Src family kinase Lyn on the plasma membranes of human neutrophils; ligand binding to LacCer activates Lyn, resulting in neutrophil functions, such as superoxide generation and migration (Iwabuchi and Nagaoka, Lactosylceramide-enriched glycosphingolipid signaling domain mediates superoxide generation from human neutrophils, Blood 100, 1454-1464, 2002 and Sato et al. Induction of human neutrophil chemotaxis by Candida albicans-derived beta-1,6-long glycoside side-chain-branched beta glycan, J. Leukoc. Biol. 84, 204-211, 2006). Neutrophilic differentiated HL-60 cells (D-HL-60 cells) express almost the same amount of LacCer as neutrophils. However, D-HL-60 cells do not have Lyn-associated LacCer-enriched lipid rafts and lack LacCer-mediated superoxide-generating and migrating abilities. Here, we examined the roles of LacCer molecular species of different fatty acid compositions in these processes. Liquid chromatography-mass spectrometry analyses revealed that the very long fatty acid C24:0 and C24:1 chains were the main components of LacCer (31.6% on the total fatty acid content) in the detergent-resistant membrane fraction (DRM) from neutrophil plasma membranes. In contrast, plasma membrane DRM of D-HL-60 cells included over 70% C16:0-LacCer, but only 13.6% C24-LacCer species. D-HL-60 cells loaded with C24:0 or C24:1-LacCer acquired LacCer-mediated migrating and superoxide-generating abilities, and allowed Lyn coimmunoprecipitation by anti-LacCer antibody. Lyn knockdown by siRNA completely abolished the effect of C24:1-LacCer loading on LacCer-mediated migration of D-HL-60 cells. Immunoelectron microscopy revealed that LacCer clusters were closely associated with Lyn molecules in neutrophils and C24:1-LacCer-loaded D-HL-60 cells, but not in D-HL-60 cells or C16:0-LacCer-loaded cells. Taken together, these observations suggest that LacCer species with very long fatty acids are specifically necessary for Lyn-coupled LacCer-enriched lipid raft-mediated neutrophil superoxide generation and migration.

Allergic inflammatory reaction is involved in necrosis of human pulmonary dirofilariasis

AIMS

To determine whether, in view of the massive inflammatory cell infiltration and the rounded rather than wedge-shaped character of pulmonary lesions in dirofilariasis, the inflammatory response against the worm contributes to the coagulative necrosis, in addition to an ischaemic process.

METHODS AND RESULTS

The histopathological features of 13 resected dirofilariasis cases with well-defined nodules ranged from 10 to 30 mm were analysed. On routine histology and using immunohistochemistry, the peripheral encapsulating wall showed mild to severe infiltration of eosinophils, lymphocytes and plasma cells and a histiocytic reaction in all cases, often with necrotic eosinophils seen within the necrosis (84.6%) and inflammatory changes in the adjacent lung (38.5%). The CD4+ lymphocyte count (80.8 +/- 33.4) was greater than that of CD8+ lymphocytes (24.5 +/- 16.9) in the central necrosis and vice versa in the wall. In the necrotic regions, disruption of the pulmonary artery (61.5%) and extravasation of the torn worm (23.1%) could be seen.

CONCLUSIONS

These findings indicate that an allergic inflammatory reaction, mediated by eosinophils and lymphocytes, is involved in the formation of the dirofilarial necrotizing granuloma rather than infarction caused simply by embolism.

Proteomic analysis of plasma membrane lipid rafts of HL-60 cells

Neutrophils acquire phagocytic activity as they differentiate. Recently, plasma membrane lipid rafts have been shown to play important roles in the process of phagocytosis in neutrophils. To characterize the proteins involved in phagocytosis and to elucidate the process by which they acquire phagocytic activity, we investigated by nano-LC-MS/MS analysis the changes in protein composition of plasma membrane lipid rafts during DMSO-induced differentiation of the human leukemia cell line HL-60 cells into neutrophilic lineage. Based on the spectrum counts of 147 proteins identified, 25 proteins were upregulated and 49 were downregulated by DMSO treatment. CD11b/CD18 subunits of beta2-integrin Mac-1, CD35, and GPI-80, which are known to be upregulated during differentiation, were dominantly detected in the lipid rafts of DMSO-treated cells. Many known membrane proteins, G proteins, and cytoskeletal proteins were also detected and they showed characteristic distributions. Absolute quantification of nine proteins in the lipid rafts using internal standard peptides labeled with stable isotopes showed that the amount of protein almost corresponded to the results obtained by spectrum count. Identified proteins, expression of which was altered by DMSO treatment, are expected to be candidate proteins involved in differentiation and functions of neutrophils.

Induction of human neutrophil chemotaxis by Candida albicans-derived -1,6-long glycoside side-chain-branched -glucan

Polysaccharide beta-1,3-D-glucans (beta-glucans) are components of the cell wall of various fungi and show immunomodulatory activities. beta-Glucans have been reported to enhance neutrophil accumulation during pathogenic fungi-induced lung inflammation. Therefore, we examined whether beta-glucans themselves possess chemotactic activities for human neutrophils. Among several kinds of beta-glucans, beta-1,6-long glucosyl side-chain-branched beta-glucan, isolated from Candida albicans [Candida soluble beta-D-glucan (CSBG)], dose-dependently induced neutrophil migration in a Boyden chamber system. In contrast, 1,6-monoglucosyl-branched beta-glucans, such as Sparassis crispa-derived beta-glucan (SCG) and grifolan (GRN), which were derived from nonpathogenic fungi, hardly induced neutrophil migration. Moreover, CSBG-induced neutrophil migration was inhibited completely by liposomes containing neutral glycosphingolipid lactosylceramide (LacCer; Galbeta1-4Glc-ceramide) but not NeuAcalpha2-3Galbeta1-4Glcbeta1-1'-Cer ganglioside. Furthermore, binding experiments demonstrated that CSBG bound to glycosphingolipids (such as LacCer) with a terminal galactose residue; however, SCG and GRN (1,6-monoglucosyl-branched beta-glucans) did not bind to LacCer. It is important that a Src kinase inhibitor protein phosphatase 1, a phosphatidylinositol-3 kinase (PI-3K) inhibitor wortmannin, and a Galpha(i/o) inhibitor pertussis toxin inhibited neutrophil migration toward CSBG. Taken together, our results suggest that beta-1,6-long glucosyl side-chain-branched beta-glucan CSBG binds to LacCer and induces neutrophil migration through the activation of Src family kinase/PI-3K/heterotrimeric G-protein signal transduction pathways.

Decrease in the glyceraldehyde derived advanced glycation end products in the sera of patients with Vogt-Koyanagi-Harada disease

BACKGROUND/AIMS

Advanced glycation end products (AGEs) are considered to act as mediators of both age related pathologies and diabetic complications. It was recently reported that glyceraldehyde derived AGE (AGE-2) has a strong biological effect on various diseases. The aim of this study was to investigate the serum AGE-2 levels in Vogt-Koyanagi-Harada (VKH) disease.

METHODS

Sera were obtained from 31 patients with active VKH. 20 of these 31 patients were treated with systemic corticosteroids. As controls, 33 healthy volunteers were also examined. The serum AGE-2 levels were determined with a competitive enzyme linked immunosorbent assay using AGE-2 polyclonal antibody.

RESULTS

The mean AGE-2 level in the sera of patients with VKH disease was 4.91 (SD 2.23) U/ml, which was significantly lower than that of the healthy control subjects (8.32 (2.94), p<0.001). The average serum AGE-2 level significantly increased to 13.49 (2.17) U/ml after the patients were treated with systemic corticosteroids (p<0.001).

CONCLUSIONS

These results suggest that AGE-2 may be involved in the onset of VKH disease.

Platelets activated by collagen through the immunoreceptor tyrosine-based activation motif in the Fc receptor gamma-chain play a pivotal role in the development of myocardial ischemia-reperfusion injury

Platelet activation and the formation of platelet microaggregates in coronary vessels play pivotal roles in myocardial ischemia and reperfusion injury. The Fc receptor gamma-chain (FcR gamma) is coexpressed with glycoprotein (GP) VI, forming a platelet collagen receptor, and the activation of platelets by collagen is closely coupled with tyrosine phosphorylation of the FcRgamma. To examine the functional significance of platelet FcR gamma/GPVI complex in the early phase of myocardial ischemia and reperfusion injury in mice, we performed coronary occlusion and reperfusion experiments using wild type mice and FcRgamma-deficient (FcRgamma(-/-)) mice that lack GPVI. The infarct size was significantly smaller in FcRgamma(-/-) mice subjected to occlusion and reperfusion of the coronary artery than in control FcR gamma(+/+) mice. Twenty-four hours after the reperfusion, electron microscopy of the injured tissue showed substantially more platelet aggregation and occlusive platelet microthrombi in the capillaries of the damaged areas of the wild type mice than in those of the FcR gamma(-/-) mice. Platelet Syk was scarcely activated in the FcR gamma(-/-) mice after myocardial ischemia and reperfusion, but significantly activated in the FcR gamma(+/+) mice. CD11b expression on neutrophils was elevated after myocardial ischemia and reperfusion in both mouse groups, whereas myeloperoxidase activity in the injured areas was significantly lower in the FcRgamma(-/-) mice than in the FcRgamma(+/+) mice. These results suggest that the collagen-induced activation of platelets through the FcR gamma plays a pivotal role in the extension of myocardial ischemia-reperfusion injury. FcRgamma and GPVI may be important therapeutic targets for myocardial ischemia-reperfusion injury.

Glucosamine, a naturally occurring amino monosaccharide, suppresses the ADP-mediated platelet activation in humans

OBJECTIVE

To evaluate the anti-thrombotic action of glucosamine, a naturally occurring amino monosaccharide, platelets were stimulated with ADP in the presence of glucosamine, and its effects on platelet functions were examined.

MATERIALS AND METHODS

Human platelet-rich plasma was stimulated with 2.5 microM ADP in the presence of glucosamine (0.01 approximately 1 mM) or other aminosugars (N-acetyl-glucosamine, galactosamine or N-acetyl-galactosamine, 1 mM), and platelet aggregation was monitored. Furthermore, the effects of glucosamine on the thromboxane A2 production, release of granule contents, intracellular calcium mobilization and phosphorylation of Syk (a 72 kD protein tyrosine kinase) were evaluated following ADP-stimulation. In addition, the binding of [3H] ADP to its receptors was examined.

RESULTS

Glucosamine (>0.01 mM) dose-dependently suppressed platelet aggregation in response to ADP (p < 0.05), whereas N-acetyl-glucosamine, galactosamine or N-acetyl-galactosamine (1 mM) did not affect the ADP-induced platelet aggregation. Furthermore, glucosamine (>0.1 mM) inhibited the extracellular release of granule contents (ATP and platelet factor 4) and production of thromboxane A2 from ADP-stimulated platelets (p < 0.05). Moreover, glucosamine significantly repressed the intracellular calcium mobilization at >0.1 mM and phosphorylation of Syk at >0.01 mM upon ADP-stimulation (p < 0.05). In addition, glucosamine (>0.1 mM) inhibited the binding of ADP to its receptors (p < 0.05).

CONCLUSION

Glucosamine is able to suppress platelet aggregation, release of granule constituents, thromboxane A2 production, calcium mobilization and phosphorylation of Syk possibly via the inhibition of ADP-binding to the receptors. Glucosamine could be expected as a novel anti-platelet agent for thrombotic disorders due to its suppressive actions on platelets.

Centrosome hyperamplification and chromosomal damage after exposure to radiation

OBJECTIVE

In order to elucidate the effects of radiation on centrosome hyperamplification (CH), we examined the centrosome duplication cycle in KK47 bladder cancer cells following irradiation.

METHODS

KK47 cells were irradiated with various doses of radiation and were examined for CH immunostaining for gamma-tubulin.

RESULTS

Nearly all control cells contained one or two centrosomes, and mitotic cells displayed typical bipolar spindles. The centrosome replication cycle is well regulated in KK47. Twenty-four hours after 5-Gy irradiation, approximately 80% of irradiated cells were arrested in G2 phase, and at 48 h after irradiation, 56.9% of cells contained more than two centrosomes. Laser scanning cytometry performed 48 h after irradiation showed the following two pathways: (1) unequal distribution of chromosomes to daughter cells, or (2) failure to undergo cytokinesis, resulting in polyploidy. With mitotic collection, M-phase cells with CH could be divided into G1 cells with micronuclei and polyploidal cells. Fluorescence in situ hybridization analysis showed clear signs of chromosomal instability (CIN) at 48 h after irradiation. The present study had two major findings: (1) continual duplication of centrosomes occurred in the cell cycle-arrested cells upon irradiation, leading to centrosome amplification; (2) cytokinesis failure was due to aberrant mitotic spindle formation caused by the presence of amplified centrosomes. Abnormal mitosis with amplified centrosomes was detected in the accumulating G2/M population after irradiation, showing that this amplification of centrosomes was not caused by failure to undergo cytokinesis, but rather that abnormal mitosis resulting from amplification of centrosomes leads to cytokinesis block.

CONCLUSION

These results suggest that CH is a critical event leading to CIN following exposure to radiation.

Isolation and mass spectrometry characterization of molecular species of lactosylceramides using liquid chromatography-electrospray ion trap mass spectrometry

Reverse-phase liquid chromatography/electrospray ion trap mass spectrometry (LC-ESI-MSn) was established for identification of the molecular species of lactosylceramides. Lactosylceramides derived from porcine blood cells were separated on a CapcellPak C8 column using a mixture of methanol and 1 mM ammonium formate from the C16 to C26 fatty acyl chains based on the length of total carbon chains and the nature of sphingoid bases (w'') and fatty acyl chains (Y0'-w'') was identified by MS3 as their [M+H]+ ions. The same number of fatty acyl moieties appeared in the order of unsaturated, (2-)hydroxylated, and saturated components. The molecular species of lactosylceramides derived from porcine blood cells totaled more than 33 and included mainly C24:0-d18:1, Ch24:0-d18:1, Ch24:1-d18:1, C24:1-d18:1, and C22:0-d18:1 in addition to 28 minor species from C16:0 to C26:0 fatty acyl moieties. The molecular species of lactosylceramides in the membrane microdomain fraction of HL-60 cells (70% were differentiated into macrophage-lineage cells) were identified as C24:0-d18:1, C24:1-d18:1, C22:0-d18:1, C16:0-d18:1, and more than 21 other minor species. Our results suggest that reverse-phase LC-ESI-MSn is a useful and simple method for identification of lactosylceramide molecular species.

Hepatocyte growth factor receptor is a coreceptor for adeno-associated virus type 2 infection

After the first attachment of virus to the cell surface through a primary receptor, efficient entry of virus requires the presence of a coreceptor. For adeno-associated virus type 2 (AAV2) infection, heparan sulfate proteoglycan is supposed as the primary receptor, and alphavbeta5 integrin and FGFR1 are reported to act as coreceptors. In this study, we were able to demonstrate that hepatocyte growth factor receptor, c-Met, is also a coreceptor for AAV2 infection. AAV2-mediated transgene analyses revealed that c-Met expression significantly up-regulated transgene expression without increasing AAV2 cell binding. Moreover, a viral overlay assay elucidated the physical interaction between AAV2 and the beta subunit of c-Met. These data suggest that c-Met plays the role of coreceptor for AAV2 infection by facilitating AAV2 internalization into the cytoplasm.

Immunoregulatory defects of V alpha 24V+ beta 11+ NKT cells in development of Wegener's granulomatosis and relapsing polychondritis

The frequency of either CD4(-)8(-) (double negative; DN) or CD4(+) V alpha 24(+)V beta 11(+) NKT cells, the expression of CD1d and the binding of CD1d-tetramer loaded with alpha-galactosylceramide (alpha-GalCer) to NKT cells were analysed in peripheral blood mononuclear cells (PBMCs) of patients with Wegener's granulomatosis (WG), relapsing polychondritis (RP) and healthy subjects (HS). DN and CD4(+) V alpha 24(+)V beta 11(+) NKT cells as well as CD1d-alpha-GalCer tetramer-positive NKT cells, were significantly decreased in number in both WG and RP patients compared to those from HS. When cytokine profiles were analysed in these PBMCs upon stimulation with phorbol ester and calcium ionophore, CD4(+) T cells from patients with WG and RP exhibited a Th1 bias, whereas CD4(+) NKT cells from WG patients in remission showed a Th2 bias. These findings suggest that NKT cells (especially CD4(+) NKT cells) play a regulatory role in Th1 autoimmunity in patients with WG and RP. The reduction in NKT cell counts appears to be associated with the low responsiveness to alpha-GalCer. The dysfunction of NKT cells to recognize ligands such as alpha-GalCer may also contribute to the defects observed in NKT cells from WG and RP patients.

Distribution and Transport of Cholesterol-rich Membrane Domains Monitored by a Membrane-impermeant Fluorescent Polyethylene Glycol-derivatized Cholesterol

Cholesterol-rich membrane domains function in various membrane events as diverse as signal transduction and membrane traffic. We studied the interaction of a fluorescein ester of polyethylene glycol-derivatized cholesterol (fPEG-Chol) with cholesterol-rich membranes both in cells and in model membranes. Unlike filipin and other cholesterol probes, this molecule could be applied as an aqueous dispersion to various samples. When added to live cells, fPEG-Chol distributed exclusively in the outer plasma membrane leaflet and was enriched in microdomains that dynamically clustered by the activation of receptor signaling. The surface-bound fPEG-Chol was slowly internalized via clathrin-independent pathway into endosomes together with lipid raft markers. Noteworthy, fPEG-Chol could be microinjected in the living cells in which we found Golgi apparatus as the sole major organelle to be labeled. PEG-Chol, thus, provides a novel, sensitive probe for unraveling the dynamics of cholesterol-rich microdomains in living cells.

Sphingosine-dependent protein kinase-1, directed to 14-3-3, is identified as the kinase domain of protein kinase C delta

Some protein kinases are known to be activated by d-erythro-sphingosine (Sph) or N,N-dimethyl-d-erythro-sphingosine (DMS), but not by ceramide, Sph-1-P, other sphingolipids, or phospholipids. Among these, a specific protein kinase that phosphorylates Ser60, Ser59, or Ser58 of 14-3-3beta, 14-3-3eta, or 14-3-3zeta, respectively, was termed "sphingosine-dependent protein kinase-1" (SDK1) (Megidish, T., Cooper, J., Zhang, L., Fu, H., and Hakomori, S. (1998) J. Biol. Chem. 273, 21834-21845). We have now identified SDK1 as a protein having the C-terminal half kinase domain of protein kinase Cdelta (PKCdelta) based on the following observations. (i). Large-scale preparation and purification of proteins showing SDK1 activity from rat liver (by six steps of chromatography) gave a final fraction with an enhanced level of an approximately 40-kDa protein band. This fraction had SDK1 activity approximately 50000-fold higher than that in the initial extract. (ii). This protein had approximately 53% sequence identity to the Ser/Thr kinase domain of PKCdelta based on peptide mapping using liquid chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry data. (iii). A search for amino acid homology based on the BLAST algorithm indicated that the only protein with high homology to the approximately 40-kDa band is the kinase domain of PKCdelta. The kinase activity of PKCdelta did not depend on Sph or DMS; rather, it was inhibited by these sphingoid bases, i.e. PKCdelta did not display any SDK1 activity. However, strong SDK1 activity became detectable when PKCdelta was incubated with caspase-3, which releases the approximately 40-kDa kinase domain. PKCdelta and SDK1 showed different lipid requirements and substrate specificity, although both kinase activities were inhibited by common PKC inhibitors. The high susceptibility of SDK1 to Sph and DMS accounts for their important modulatory role in signal transduction.

Acid exposure potentiates intercellular adhesion molecule-1 and e-cadherin expression on A549 alveolar lining epithelial cells

Recruitment of neutrophils into the alveoli plays a major role in the pathogenesis of acid-induced pneumonitis. Preliminary data suggest that alteration in the expression of cellular adhesion molecules on the airway epithelial cells may play an important role in the recruitment of neutrophils following acid-induced lung injury. The aim of this study was to evaluate the change in the surface expression of intercellular adhesion molecule-1 (ICAM-1), E-cadherin, and vascular cell adhesion molecule -1 (VCAM-1) on acid-exposed A549 alveolar lining epithelial cells by flow cytometry and confocal laser microscopy. Acid exposure changed cell morphology, increased cell adhesion after trypsin-EDTA treatment, and up-regulated the expression of ICAM-1 and E-cadherin but not of VCAM-1. The up-regulation of ICAM-1 expression will induce the dysfunction of epithelial cells with or without accumulation of neutrophils in air spaces. Because the distribution of E-cadherin in acid-exposed A549 cells was at the sites where the cells attached to culture dish but not at the intercellular junctions between adjoining cells, up-regulated expression of E-cadherin will rather result in alterations of epithelial morphology and function of epithelial barrier. In addition, pentoxifylline suppressed the up-regulation of ICAM-1 and E-cadherin expression and may therefore attenuated the airway inflammation in acid-induced pneumonitis.

A sphingosine-dependent protein kinase that specifically phosphorylates 14-3-3 (SDK1) is identified as the kinase domain of PKCdelta: a preliminary note

A specific protein kinase that phosphorylates Ser60, Ser59, or Ser58 of 14-3-3beta, eta, or zeta, respectively, only in the presence of sphingosine (Sph) or N,N-dimethyl-Sph (DMS), was termed "sphingosine-dependent protein kinase-1" (SDK1) [J. Biol. Chem. 273(34) (1998) 21834]. We have now identified SDK1 as a protein having the same amino acid sequence as in the C-terminal-half kinase domain of PKCdelta, with approximately 40 kDa molecular mass, based on large-scale purification of a protein from rat liver, and partial sequence using three different combinations of LC-MS or LC-MS/MS with respective search engine. PKCdelta did not display any SDK1 activity and PKCdelta activity was inhibited by Sph and DMS. However, strong SDK1 activity, only in the presence of Sph or DMS, became detectable when PKCdelta was incubated with caspase-3, which releases the approximately 40 kDa kinase domain.

Attenuated nuclear shrinkage in neurones with nuclear inclusions of SCA1 brains

BACKGROUND

Spinocerebellar ataxia type 1 (SCA1) is one of the autosomal dominant neurodegenerative disorders commonly linked to pathological expansion of the CAG repeat of the relevant gene. Nuclear inclusions and neurodegeneration are both triggered by this pathological expansion of the CAG/polyglutamine repeat on ataxin-1, but it remains to be determined whether or not nuclear inclusion formation is associated with accelerated neurodegeneration.

OBJECTIVE

To examine the influence of nuclear inclusions on nuclear size and deformity in human brains from patients suffering from SCA1.

MATERIAL

Pontine sections of brains obtained at necropsy from seven patients with SCA1 and five controls.

METHODS

The size and deformity of each neuronal nucleus was quantified. Nuclei with and without inclusions were examined separately to assess the possible influence of nuclear inclusions on neurodegeneration.

RESULTS

Nuclear shrinkage and deformity were more marked in SCA1 brains than in controls. This shrinkage was attenuated in neurones containing nuclear inclusions.

CONCLUSIONS

The existence of nuclear inclusions in SCA1 is presumably linked to a mechanism that attenuates rather than accelerates nuclear shrinkage. This in vivo finding may provide a clue to constructing a rational therapeutic strategy for combating neurodegeneration associated with nuclear inclusions.

VEGF regulates the proliferation of acid-exposed alveolar lining epithelial cells

BACKGROUND

Acid induced pneumonitis resulting in acute respiratory distress syndrome (ARDS) is characterised by increased alveolar permeability and accumulation of neutrophils. It is hypothesised that vascular endothelial growth factor (VEGF) is involved in the development of lung oedema. Furthermore, lower levels of VEGF are detected in bronchoalveolar lavage fluid from patients with ARDS than from non-ARDS patients. We hypothesised that VEGF acts cytoprotectively and have investigated this possibility in vitro with A549 cells.

METHODS

A549 cells were incubated in 24 well culture dishes 24 hours before exposure to acid, then incubated with serum free medium containing various concentrations of HCl for 30 minutes at 37 degrees C in 5% CO(2). The acidified medium was changed to normal complete medium; at specified incubation periods the supernatants were collected and the VEGF concentration measured and the number of adherent cells counted.

RESULTS

Proliferation of A549 cells and VEGF production were suppressed for at least 48 hours in HCl at a concentration of 50 mM. Restoration of cellular proliferation occurred following exogenous administration of VEGF (concentration of 1-250 ng/ml) and was inhibited by co-incubation with neutralising anti-VEGF antibody, indicating an interaction between VEGF molecules and A549 cells. Control cells were not influenced by administration of exogenous VEGF or anti-VEGF antibody. Treatment with neutralising anti-VEGF receptor (VEGFR) antibodies against VEGFR-1 and VEGFR-2 suppressed proliferation of acid exposed A549 cells but had no effect on control cells.

CONCLUSIONS

Exogenous VEGF interacts with VEGFR-1 and VEGFR-2 on the surface and regulates the proliferation of injured alveolar lining epithelial cells in an autocrine or paracrine fashion.

Primary gastric T-cell lymphoma not associated with human T-lymphotropic virus type I: a case report and review of the literature

Primary gastric T-cell lymphoma (PGTL) not associated with human T-lymphotropic virus type I (HTLV-I) is extremely rare and such a case is reported herein. The patient was a 58-year-old Japanese male presenting with submucosal tumor of the stomach identified on endoscopic examination. The lesion was diagnosed as non-Hodgkin's lymphoma by endoscopic biopsy and classified as peripheral T-cell lymphoma, unspecified, due to clonal rearrangement of the T-cell receptor beta (TCR) gene and expression of TCR beta protein in the absence of B-cell genotypes and phenotypes. Unlike previously reported cases of HTLV-I-unassociated PGTL, lymphoma in the current case was characterized histologically as "low grade" and phenotypically as CD4+, TIA-1+, granzyme B+, and CD103-. The lymphoma responded well to chemotherapy and radiation, and the patient was well with no detectable disease 10 months after initiation of therapy. A review of patients with PGTL in the literature revealed a few long-term survivors, and the investigation of therapeutic strategies for PGTL is, therefore, necessary.

Short-term and long-term effects of low total pressure on gas exchange rates of spinach

In this study, spinach plants were grown under atmospheric and low pressure conditions with constant O2 and CO2 partial pressures, and the effects of low total pressure on gas exchange rates were investigated. CO2 assimilation and transpiration rates of spinach grown under atmospheric pressure increased after short-term exposure to low total pressure due to the enhancement of leaf conductance. However, gas exchange rates of plants grown at 25 kPa total pressure were not greater than those grown at atmospheric pressure. Stomatal pore length and width were significantly smaller in leaves grown at low total pressure. This result suggested that gas exchange rates of plants grown under low total pressure were not stimulated even with the enhancement of gas diffusion because the stomatal size and stomatal aperture decreased.

Paradoxical absence of nuclear inclusion in cerebellar Purkinje cells of hereditary ataxias linked to CAG expansion

Degeneration of cerebellar cortex is one of the principal features of hereditary ataxias linked to expansion of CAG repeat. In an attempt to clarify possible correlation between neuronal depletion and neuronal intranuclear inclusions, both triggered by the pathological expansion of CAG repeat, cerebellar sections from SCA1, SCA2, SCA3, and DRPLA cases were immunostained with anti-ubiquitin or anti-expanded polyglutamine antibody (1C2) and were screened for the presence of neuronal intranuclear inclusions. Although the degree of cerebellar degeneration varied greatly, cerebellar Purkinje cells were uniformly characterised by the absence of neuronal intranuclear inclusion. Complete absence of neuronal intranuclear inclusion in Purkinje cells is apparently paradoxical and hardly explained if neuronal intranuclear inclusion formation is positively correlated to a mechanism accelerating neuronal death. It may, otherwise, suggest an intrinsic link between neuronal intranuclear inclusion formation and neurodegeneration in opposite directions in human Purkinje cells, more or less affected in these CAG repeat disorders.

Lactosylceramide-enriched glycosphingolipid signaling domain mediates superoxide generation from human neutrophils

This study is focused on the functional significance of neutrophil lactosylceramide (LacCer)-enriched microdomains, which are involved in the initiation of a signal transduction pathway leading to superoxide generation. Treatment of neutrophils with anti-LacCer antibody, T5A7 or Huly-m13, induced superoxide generation from the cells, which was blocked by PP1, a Src kinase inhibitor; wortmannin, a phosphatidylinositol-3 kinase inhibitor; SB203580, a p38 mitogen-activated protein kinase (MAPK) inhibitor; and H7, an inhibitor for protein kinase C. When promyelocytic leukemia HL-60 cells were differentiated into neutrophilic lineage by dimethyl sulfoxide (DMSO) treatment, they acquired superoxide-generating activity but did not respond to anti-LacCer antibodies. Density gradient centrifugation revealed that LacCer and Lyn were recovered in detergent-insoluble membrane (DIM) of neutrophils and DMSO-treated HL-60 cells. However, immunoprecipitation experiments indicated that LacCer was associated with Lyn in neutrophils but not in DMSO-treated HL-60 cells. Interestingly, T5A7 induced the phosphorylation of Lyn in neutrophils but not in DMSO-treated HL-60 cells. Moreover, T5A7 induced the phosphorylation of p38 MAPK in neutrophils. T5A7-induced Lyn phosphorylation in neutrophil DIM fraction was significantly enhanced by cholesterol depletion or sequestration with methyl-beta-cyclodextrin or nystatin. Collectively, these data suggest that neutrophils are characterized by the presence of cell surface LacCer-enriched glycosphingolipid signaling domain coupled with Lyn and that the ligand binding to LacCer induces the activation of Lyn, which may be suppressibly regulated by cholesterol, leading to superoxide generation through the phosphatidylinositol-3 kinase-, p38 MAPK-, and protein kinase C-dependent signal transduction pathway.

A cathelicidin family of human antibacterial peptide LL-37 induces mast cell chemotaxis

The mast cell is one of the major effector cells in inflammatory reactions and can be found in most tissues throughout the body. During inflammation, an increase in the number of mast cells in the local milieu occurs, and such accumulation requires directed migration of this cell population. As it has previously been reported that the human cathelicidin-derived antibacterial peptide, LL-37, stimulates the degranulation of mast cells, we hypothesized that LL-37 could be a mast cell chemotaxin. The present study shows that LL-37 is a potent chemotactic factor for mast cells. The chemotactic response was dose-dependent and bell-shaped, reaching an optimal concentration of 5 microg/ml. In addition, checkerboard analysis showed that cell migration towards this peptide was chemotactic rather than chemokinetic. Moreover, Scatchard analysis using 125I-labelled LL-37-derived peptide revealed that LL-37 has at least two classes of receptors, namely high- and low-affinity receptors, on mast cells. Furthermore, the competitive binding assay suggested that LL-37 is unlikely to utilize formyl peptide receptor-like 1 (FPRL1), a functional LL-37 receptor for neutrophil and monocyte migration, on mast cells. In addition, the treatment of cells with pertussis toxin and phospholipase C inhibitor, U-73122, inhibited LL-37-mediated migration, indicating that LL-37 induces mast cell chemotaxis through a Gi protein-phospholipase C signalling pathway. These results show that besides its antibacterial activities, LL-37 may have the potential to recruit mast cells to inflammation foci.

Prostaglandin E1 protects cultured spinal neurons against the effects of nitric oxide toxicity

The effects of prostaglandin (PG) E(1) on NO neurotoxicity were examined using rat cultured spinal neurons. Rat cultured spinal neurons exposed to the NO donor, 2,2'-(hydroxynitrosohydrazono) bis-ethanamine (NOC18), showed neurotoxic effects that were accompanied by apoptotic nuclear change, free radical generation, a reduction in glutathione, and mitochondrial dysfunction. PGE(1), at concentrations of 1-100 nM, protected cultured spinal neurons from NO toxicity by reversing the oxidative and pro-apoptotic properties elicited by NOC18 exposure. The administration of PGE(1) increased the intracellular cyclic AMP (cAMP) levels in cultured spinal neurons. In addition, reverse transcriptase-polymerase chain reaction (RT-PCR) analysis confirmed the existence of EP4, a cAMP-elevating PGE receptor, in cultured spinal neurons. The protective effects of PGE(1) against NO neurotoxicity was partially blocked by an inhibitor of MEK [the mitogen-activated protein kinase (MAPK)/extracellular-signal-regulated kinase (ERK) kinase], suggesting that the MAPK/ERK pathway may play a significant role in the activity of PGE(1). PGE(1) up-regulated the expression of the anti-apoptotic protein, Bcl-2, as determined by Western blot analysis. PGE(1) also induced the expression of thioredoxin in cultured spinal neurons. Our data indicate that PGE(1) exerts a protective action against NO neurotoxicity in cultured spinal neurons, and suggests a therapeutic potential of PGE(1) against spinal cord disease, such as amyotrophic lateral sclerosis.

Epithelial cell-derived human beta-defensin-2 acts as a chemotaxin for mast cells through a pertussis toxin-sensitive and phospholipase C-dependent pathway

Mast cells are known to accumulate at the sites of inflammation in response to chemoattractants generated in the local milieu. Since human beta-defensin-2 (hBD-2) is generated in several epithelial tissues where mast cells are present and because we have recently reported that this human antibacterial peptide induces mast cell degranulation, we thus hypothesized that hBD-2 could be a mast cell chemotaxin. Here we report that hBD-2 directly and specifically induces mast cell migration with an optimal concentration of 3 microg/ml. Checkerboard analysis showed that the migration was more chemotactic rather than chemokinetic. Moreover, Scatchard analysis using 125I-labeled hBD-2 revealed that mast cells have at least two classes of receptors, high- and low-affinity receptors, for this peptide. Moreover, the competitive binding assay suggested that hBD-2 is unlikely to utilize CCR6, a functional receptor for hBD-2-mediated dendritic and T cell migration, on mast cells. In addition, treatment of mast cells with G protein inhibitor, pertussis toxin, and phospholipase C inhibitor, U-73122, abolished the cell chemotaxis in response to hBD-2, indicating that the G protein-phospholipase C signaling pathway is involved in hBD-2-induced mast cell activation. Thus, we suggest that hBD-2, which was originally believed to be involved in innate host defense, may participate in the recruitment of mast cells to inflammation foci.

Negative regulation of LPS-stimulated expression of inducible nitric oxide synthase by AP-1 in macrophage cell line J774A.1

The level of NOS II mRNA was markedly increased during 24 h lipopolysaccharide (LPS) stimulation, but showed no further increase thereafter. On the other hand, the level of NOS II mRNA in J774A.1 cells transfected with an expression vector containing the rat csk cDNA (J.Csk) was significantly increased during 3 h LPS stimulation, but rather decreased thereafter. Although no significant difference was observed in the activation of NF-kappaB by LPS among parental J774A.1, J774A.1 transfected with promoterless vector (J.pBK), and J.Csk cells, activity of c-Jun N-terminal kinase (JNK) and nuclear translocation of nuclear factor activator protein-1 (AP-1) were markedly upregulated in the J.Csk cells. Then luciferase reporter vectors containing NOS II promoter with mutations in two AP-1-like sites (U site, -1126 approximately -1120; L site, -524 approximately -518) were transiently transfected in J774A.1 cells. The promoter activity following LPS stimulation for 24 h was significantly increased by mutation at the L site, but not by mutation at the U site, suggesting that NOS II expression is negatively regulated, at least in part, through the AP-1-like L site in response to LPS.

Declining trend in the in-hospital case-fatality rate from acute myocardial infarction in Miyagi Prefecture from 1980 to 1999

The case-fatality rate from acute myocardial infarction (AMI) appears to have been declining in recent decades, so the present study reviewed the trend in in-hospital case-fatalities from AMI in Miyagi Prefecture, Japan, 1980-1999. The causes of death and the effects of gender and age on the trend were also analyzed. From the AMI registration database of the Miyagi Study Group for AMI, 12,961 cases of AMI were analyzed. The 30-day in-hospital case-fatality was calculated from the data for 1980-1999: data for causes of death were available for 1980-1997, and the data concerning primary percutaneous transluminal coronary angioplasty (PTCA) for AMI were available for 1997-1999. The in-hospital case-fatality rate declined from 17.0% in the early 80s to 7.3% in the late 90s (approximately 57% reduction). The in-hospital case-fatality rate was higher in female patients. Rhythm failure substantially decreased in the late 1980s. Pump failure is decreasing, but is still the biggest problem. The in-hospital case-fatality rate was significantly lower in patients received PTCA. The declining trend in the in-hospital case-fatality rate suggests the benefits of current therapeutic procedures, including primary PTCA, for AMI. Pump failure is an important target for further decreasing the trend.

Allograft inflammatory factor-1 augments production of interleukin-6, -10 and -12 by a mouse macrophage line

Mouse allograft inflammatory factor-1 (AIF-1) cDNA was cloned and the AIF-1-specific monoclonal antibodies were established to examine its tissue distribution. The mouse AIF-1 was highly conserved among all reported AIF-1 from a variety of species, from invertebrates to mammals, and the cloned cDNA was in good accordance with putative expressed regions of genomic sequences in the mouse major histocompatibility complex (MHC) class III region. The messages of mouse AIF-1 were abundantly expressed in the testis, moderately in the spleen and lymph nodes and slightly in the liver and thymus of normal BALB/c mice. Immunohistological examination revealed that differentiating germ cells in the testis and presumably macrophages in the red pulp of the spleen were positive for AIF-1. To analyse the function of the AIF-1, a macrophage cell line, RAW 264.7, was transfected with mouse AIF-1 cDNA. Upon stimulation with bacterial lipopolysaccharide, the transfectants that overexpressed AIF-1 showed marked morphological changes and produced significantly large amounts of interleukin (IL)-6, IL-10 and IL-12p40 but not IL-12p70 compared with control cells. No difference was noted in production of tumour necrosis factor-alpha, transforming growth factor-beta1 and IL-1alpha. These results suggest that AIF-1 plays an important role in cells of a monocyte/macrophage lineage upon stimulation with inflammatory stimuli by augmenting particular cytokine production.

Serum level of macrophage migration inhibitory factor as a useful parameter of clinical course in patients with Wegener's granulomatosis and relapsing polychondritis

Novel biological activities of macrophage migration inhibitory factor (MIF) have been rediscovered. In addition, elevation of the serum MIF level has been reported in different types of disorders, including various inflammatory and autoimmune diseases. In the present study, serum MIF levels were analyzed in patients with Wegener's granulomatosis (WG) and relapsing polychondritis. It was shown that the serum MIF levels in these patients were significantly higher than those of normal healthy controls. In a WG patient, the MIF level showed a good correlation with clinical symptoms and C-ANCA titers. Thus, serum MIF levels will be a useful laboratory parameter for following the clinical course of WG patients and determining medical treatment. The immunopathologic roles of MIF in these diseases are discussed.

Developmental and functional analyses of CD8(+) NK1.1(+) T cells in class-I-restricted TCR transgenic mice

Using a class-I-restricted T cell receptor (TCR) transgenic mice (Tgm), 2C (Valpha3.1/Vbeta 8.2, specific for L(d) + LSPFPFDL), the development and cytokine production of tg-TCR(+) NKT cells were analyzed. We found that CD8(+) or double negative (DN) NKT cells constituted a major population of NKT cells in the H-2(b/b) 2C Tgm (positive selecting background) or the H-2(b/d) 2C Tgm (negative selecting background), respectively. Virtually no NKT cells were generated in the H-2(k/k) 2C Tgm (neutral selecting background). CD8(+) NKT cells in the H-2(b/b) 2C Tgm expressed CD8alphabeta heterodimers, whereas those in the H-2(b/d) 2C Tgm expressed CD8alphaalpha homodimers. These findings suggest that development of a subpopulation of NKT cells is influenced by the H-2 molecules. Upon stimulation with anti-CD3 mAb, tg-TCR(+) NKT cells generated in the H-2(b/b) and H-2(b/d) backgrounds produced IFN-gamma, but not IL-4.

Early-onset ataxia with ocular motor apraxia and hypoalbuminemia is caused by mutations in a new HIT superfamily gene

Friedreich ataxia (FRDA), the most common autosomal recessive neurodegenerative disease among Europeans and people of European descent, is characterized by an early onset (usually before the age of 25), progressive ataxia, sensory loss, absence of tendon reflexes and pyramidal weakness of the legs. We have recently identified a unique group of patients whose clinical presentations are characterized by autosomal recessive inheritance, early age of onset, FRDA-like clinical presentations and hypoalbuminemia. Linkage to the FRDA locus, however, was excluded. Given the similarities of the clinical presentations to those of the recently described ataxia with oculomotor apraxia (AOA) linked to chromosome 9p13, we confirmed that the disorder of our patients is also linked to the same locus. We narrowed the candidate region and have identified a new gene encoding a member of the histidine triad (HIT) superfamily as the 'causative' gene. We have called its product aprataxin; the gene symbol is APTX. Although many HIT proteins have been identified, aprataxin is the first to be linked to a distinct phenotype.

Preferential recruitment of ataxin-3 independent of expanded polyglutamine: an immunohistochemical study on Marinesco bodies

In an immunohistochemical study of Marinesco bodies--a neuronal intranuclear inclusion often seen in neurons of the substantia nigra of patients with hepatic encephalopathy--it was shown that one of the polyglutamine proteins, ataxin-3, is preferentially recruited into this inclusion, whereas other polyglutamine proteins (ataxin-2 and TATA box-binding protein) are not. This suggests that recruitment of each of the polyglutamine proteins may be differently regulated. Because this nuclear inclusion is thought to be formed in response to cellular stress, as occurs in hepatic encephalopathy, even in the absence of an expanded CAG/polyglutamine repeat, recruitment of ataxin-3 and ubiquitin into Marinesco bodies may represent a cellular response to noxious external stimuli unrelated to expanded CAG/polyglutamine.

Effects of water-soluble hemicellulose from soybean hull on serum antibody levels and activation of macrophages in rats

Effects of soybean hull water-soluble hemicellulose (WSHC) on serum immunoglobulin (Ig) concentration and production of NO and IL-1beta from peritoneal macrophages were examined and compared with those of Agaricus blazei in the rat system. WSHC consisted of arabinose, galactose, xylose, glucose, and rhamnose, and the molecular weight was approximately 500000. Rats were ip administrated each sample at a dose of 0.67, 13.4, or 26.9 mg/kg/day for 14 days. The administration of WSHC resulted in significantly higher productions of IgM (p < 0.01 on day 6, p < 0.05 on day 14) and IgG (p < 0.05 on day 6) than those in other groups. When peritoneal macrophages were stimulated with various concentrations of sample (0.67, 13.4, or 26.9 mg/mL), WSHC significantly increased both NO and IL-1beta productions only at the concentration of 13.4 (mg/mL) compared with those of a saline group. These findings demonstrate that WSHC enhances humoral immunity and activation of macrophages, thereby leading to the augmentation of immune responses in rats.

Enhancement of stromal cell-derived factor-1alpha-induced chemotaxis for CD4/8 double-positive thymocytes by fibronectin and laminin in mice

Stromal cell-derived factor-1alpha (SDF-1alpha) is a chemokine abundantly expressed in the thymus. However, a potential role of SDF-1alpha in the thymus has been under consideration, since no appreciable difference was detected in the migratory responsiveness to the SDF-1alpha between cortical and medullary thymocytes. In the present study, we examined the effects of extracellular matrix (ECM) on the responsiveness of murine thymocytes to several chemokines including SDF-1alpha. In the absence of ECM, chemotactic activity of SDF-1alpha for cortical (CD4/8 double-positive) thymocytes was almost same as that for medullary (CD4 or CD8 single-positive) thymocytes. In contrast, the chemotactic activity of SDF-1alpha for cortical thymocytes was considerably (more than 10-fold) enhanced by laminin or fibronectin as compared with that for medullary thymocytes. Chemotactic activities of macrophage-derived chemokine and macrophage inflammatory protein-3beta for both cortical and medullary thymocytes were only slightly enhanced by fibronectin or laminin. Thus, fibronectin and laminin appear to enhance the chemotactic activity of SDF-1alpha for cortical thymocytes selectively. Addition of a monoclonal antibody against CD29 showed no inhibitory effect on the enhanced chemotactic activity of SDF-1alpha, suggesting that the other unknown receptor(s) is involved in this enhancement. Our present data demonstrate that SDF-1alpha in the presence of fibronectin or laminin is involved in the distribution of developing thymocytes.

Non-expanded polyglutamine proteins in intranuclear inclusions of hereditary ataxias--triple-labeling immunofluorescence study

Neuronal intranuclear inclusions (NIIs) found in CAG/polyglutamine-expansion disorders contain both expanded polyglutamine and the gene product without the CAG repeat. The gene product containing expanded polyglutamine has, therefore, been considered to be a major component of NIIs. In this immunohistochemical study, we showed recruitment of ataxin-2, ataxin-3 and TATA box binding protein (TBP) into NIIs of the pontine neurons of spinocerebellar ataxia type (SCA) 1, SCA2, SCA3 and dentatorubral-pallidoluysian atrophy brains. Triple-labeling immunofluorescence demonstrated colocalization of ataxin-2 and ataxin-3 in NIIs containing expanded polyglutamine, irrespective of the disease examined. These in vivo findings indicate that polyglutamine proteins recruited into NIIs are not restricted to their expanded form. Among these proteins, recruitment of ataxin-2 was least frequent in every case examined, suggesting that the rate of recruitment partly depends on the protein transported into NIIs. Because other proteins lacking polyglutamine motif were not detected in NIIs, it is suggested that the presence of polyglutamine is a prerequisite for these proteins to be recruited into nucleus and to form NIIs. Interaction between expanded and non-expanded polyglutamine may play roles during these processes.