Salusins protect neonatal rat cardiomyocytes from serum deprivation-induced cell death through upregulation of GRP78

Salusin-alpha and salusin-beta are newly identified bioactive peptides with hemodynamic and mitogenic activities. Recent studies have shown that salusins improve calcium uptake and protein synthesis in neonatal rat cardiomyocytes, suggesting that salusins may be regulatory factors for myocardial growth and hypertrophy. In this study, we investigated whether salusins improve the survival of cardiomyocytes after serum deprivation. Cultured neonatal cardiomyocytes were treated with or without salusins (salusin-alpha or salusin-beta) at a concentration range of 10 to 10 mol/L for 24 h under serum deprivation conditions. Cardiomyocytes viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazonium bromide assay. Cell death or apoptosis rate was identified by flow cytometry analysis. Compared to serum deprivation-only groups, cardiomyocyte viability was significantly increased in salusin-alpha or salusin-beta groups. Cell death rate was decreased after administration of 10 mol/L salusin-alpha or salusin-beta. Salusin-beta was able to decrease the apoptotic rate. Salusins also increased the expression of cardiomyocyte glucose-regulated protein 78 (GRP78) as estimated by Western blot. Furthermore, antisense oligodeoxynucleotide specifically against GRP78 attenuated or abrogated antiapoptosis or survival effects of salusin-beta. These findings suggest that salusin-alpha and salusin-beta may be a potential survival factor against serum deprivation-induced myocardial cell death and that this cardioprotective effect may involve an upregulation of GRP78 expression in cardiomyocytes.

Quantitative analysis of representative proteome components and clustering of Helicobacter pylori clinical strains

BACKGROUND

Several Helicobacter pylori proteins have been reported to be associated with severe symptoms of gastric disease. However, expression levels of most of these disease-associated proteins require further evaluation in order to clarify their relationships with gastric disease patterns. Representative proteome components of 71 clinical isolates of H. pylori were analyzed quantitatively to determine whether the protein expression levels were associated with gastric diseases and to cluster clinical isolates.

METHODS

After two-dimensional electrophoresis (2-DE) of H. pylori isolates, spot intensities were analyzed using pdquest 2-D Gel Analysis Software. The intensities of 10 representative protein spots, identified by peptide fingerprinting using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) or peptide sequencing using quadrupole TOF MS, were subjected to the nonparametric Mann-Whitney test and hierarchical agglomerative cluster analysis. The relationship between clusters and gastric diseases was analyzed by the chi-squared test.

RESULTS

Although the spot intensities of the 10 representative proteins were highly variable within each gastric disease group, the expression levels of CagA, UreB, GroEL, EF-Tu, EF-P, TagD, and FldA showed some significant differences among the gastric disease patterns. On the basis of the 10 target protein intensities, hierarchical agglomerative cluster analysis generated a dendrogram with clusters indicative of chronic gastritis/gastric cancers and gastric/duodenal ulcers.

CONCLUSION

These results indicated that quantitative analysis of proteome components is a feasible method for examining disease-associated proteins and clustering clinical strains of H. pylori.

Influence of endothelial cells on vascular smooth muscle cells phenotype after irradiation: implication in radiation-induced vascular damages

Damage to vessels is one of the most common effects of therapeutic irradiation on normal tissues. We undertook a study in patients treated with preoperative radiotherapy and demonstrated in vivo the importance of proliferation, migration, and fibrogenic phenotype of vascular smooth muscle cells (VSMCs) in radiation-induced vascular damage. These lesions may result from imbalance in the cross talk between endothelial cells (ECs) and VSMCs. Using co-culture models, we examined whether ECs influence proliferation, migration, and fibrogenic phenotype of VSMCs. In the presence of irradiated ECs, proliferation and migration of VSMCs were increased. Moreover, expressions of alpha-smooth muscle actin, connective tissue growth factor, plasminogen activator inhibitor type 1, heat shock protein 27, and collagen type III, alpha 1 were up-regulated in VSMCs exposed to irradiated ECs. Secretion of transforming growth factor (TGF)-beta1 was increased after irradiation of ECs, and irradiated ECs activated the Smad pathway in VSMCs by inducing Smad3/4 nuclear translocation and Smad-dependent promoter activation. Using small interferring RNA targeting Smad3 and a TGFbeta-RII neutralizing antibody, we demonstrate that a TGF-beta1/TGF-beta-RII/Smad3 pathway is involved in the fibrogenic phenotype of VSMCs induced by irradiated ECs. In conclusion, we show the importance of proliferation, migration, and fibrogenic phenotype of VSMCs in patients. Moreover, we demonstrate in vitro that ECs influence these fundamental mechanisms involved in radiation-induced vascular damages.

The relationship between the termination of cell proliferation and expression of heat-shock protein-25 in the rat developing tooth germ

Odontoblast- and ameloblast-lineage cells acquire heat-shock protein (HSP)-25 immunoreactivity after they complete cell division during postnatal odontogenesis in rat molars. However, there are no data available concerning the relationship between the termination of cell proliferation and HSP-25 immunoreactivity during tooth morphogenesis. We compared the expression of HSP-25 in tooth germs with their proliferative activity in the rat prenatal to perinatal molar and postnatal incisor to clarify the functional significance of HSP-25 during tooth morphogenesis by immunohistochemistry using anti-HSP-25 and anti-Ki67/5-bromo-2'-deoxyuridine (BrdU). Numerous proliferating cells in developing molars were distributed throughout the tooth germ and HSP-25 immunoreactivity was recognizable in the dental epithelial and mesenchymal cells after they completed cell division. However, both cell proliferation and immunoreaction for HSP-25 are absent in the enamel knots. The distribution pattern of the proliferating cells in the incisors was basically identical to that in the prenatal molars except for the lack of non-proliferating secondary enamel knots and the sparse distribution of proliferating cells in the apical bud. Thus, HSP-25 protein is suggested to act as a switch between cell proliferation and terminal cyto-differentiation during odontogenesis.

Mechanisms of disease: atherosclerosis in autoimmune diseases

Atherosclerosis is a pathologic process affecting blood vessels, which leads to the development of cardiovascular disease. The immune system is involved in atherogenesis and in the pathogenesis of atherosclerosis. Several autoimmune rheumatic conditions, including rheumatoid arthritis, systemic lupus erythematosus and antiphospholipid syndrome, are characterized by enhanced atherosclerosis and consequently higher cardiovascular morbidity and mortality rates. Enhanced atherosclerosis, in these diseases, can manifest as overt cardiovascular diseases, but could be detected at an earlier stage by identification of abnormal endothelial function and arterial intima-media thickening. Both classical and nonclassical risk factors are presumed to contribute to atherosclerosis progression in rheumatic diseases. As atherosclerosis can be considered to be an immune-mediated process, several experimental strategies exist for its immunomodulation, including induction of immune tolerance. In this article, we briefly review the contribution of autoimmune elements, such as autoreactive lymphocytes and autoantibodies to atherosclerosis and discuss the nature of atherosclerosis in autoimmune rheumatic diseases.

An in vitro study of the effects of exposure to a GSM signal in two human cell lines: Monocytic U937 and neuroblastoma SK-N-SH

The use of mobile phones is increasing, which also increases the population's exposure to global system of mobile communications (GSM) signals. Questions of safety and possible biological effects are of concern and to date, remain largely unanswered. In order to examine possible biological effects of a GSM-like signal at a cellular level, we exposed two human cell lines (one of neuronal (SK-N-SH) and the other of monocytoid (U937) origin) to a 900 MHz RF signal, pulsed at 217 Hz, producing a specific absorption rate (SAR) of 0.2 W/kg. Putative effects were assessed by comparing radiofrequency-exposed cells to sham-exposed cells using a variety of assay techniques. For the cell line SK-N-SH, effects were specifically assessed by gene microarray, followed by real-time PCR of the genes of interest, Western blot analysis was used to measure heat shock protein levels, and flow cytometry to measure cell cycle distributions and apoptosis. Effects of radiofrequency on the cell line U937 were assessed by cell viability and cell cycle analysis. From our study of these two cell lines, we found no significant difference between sham-exposed versus radiofrequency-exposed cells in any of the assays or conditions examined.

Cystathionine β-synthase is essential for female reproductive function

In human reproduction, hyperhomocysteinemia has been reported as a risk factor for early pregnancy loss and congenital birth defects. Hyperhomocysteinemia is also recognized as a cause of maternal obstetric complications such as preeclampsia. The role of plasma hyperhomocysteinemia in female fertility was examined using cystathionine beta synthase knockout (cbs KO) mice. Cbs KO females were infertile, showed alterations in the estrus cycle and an increased progesterone response during pseudo-pregnancy induction. Both cbs KO ovaries and ovulated oocytes showed no major morphological alterations. However, placental and uterine masses were decreased at day 18 of pregnancy and showed morphological abnormalities. In cbs-KO pregnant females, the number of uterine implantation sites was not decreased despite the low number of surviving embryos. Fertility was restored when cbs-deficient ovaries were transplanted to normal ovarectomized recipients. We detected an increased uterine expression of Grp78, a marker of endoplasmic reticulum stress, which was accompanied by the decreased levels of uterine cbs mRNA in both hyperhomocysteinemic heterozygous (fertile) and homozygous (non-fertile) females. Our results indicate that cbs -/- female infertility is a consequence of the uterine failure and demonstrate that uterine endoplasmic reticulum stress and cbs expression are not determinant of infertility, suggesting that uterine dysfunction is a consequence of either hyperhomocysteinemia or other factor(s) in the uterine environment of cbs -/- animals. In summary, these studies demonstrate the potential importance of homocysteine levels for uterine handling of embryos.

Differential Expression of Defense/Stress-Related Marker Proteins in Leaves of a Unique Rice Blast Lesion Mimic Mutant (blm)

We analyzed a unique rice (Oryza sativa L.) blast lesion mimic (blm) mutant for differentially expressed proteins in leaves of one- and two-week-old seedlings manifesting the lesion mimic phenotype. Gel-based one- and two-dimensional electrophoresis (1- and 2-DGE) was performed using leaves (blm and wild-type, WT) before (stage 1, S1) and after (stage 2, S2) lesion formation. 1-DGE immunoblotting revealed potent increase in the expression of a key pathogenesis-related (PR) marker biosynthetic enzyme, naringenin 7-O-methyltransferase, involved in rice phytoalexin sakuranetin biosynthesis, and three oxidative-stress-related marker proteins, catalase, ascorbate peroxidase (APX), and superoxide dismutase (SOD) in leaves of the blm mutant. 2-D gel immunoblotting analysis with anti-APX and anti-SOD antibodies revealed newly appearing cross-reacting protein spots in blm. 2-DGE analysis detected 50 Coomassie brilliant blue-stained protein spots differentially expressed in blm. A total of 23 and 44 protein spots was excised for analysis by N-terminal amino acid sequencing and nano-electrospray ionization liquid chromatography mass spectrometry, respectively; 26 nonredundant proteins were identified. The pathogenesis-related class 5 and 10 proteins, including a new OsPR10d protein, were significantly induced in blm. The OsPR5 protein spot was stained with Pro-Q Diamond phosphoprotein gel stain suggesting OsPR5 to be a putative phosphoprotein. Surprisingly, protein spot 20, a leaf OsPR10b, showed identity to a rice root-specific PR-10 (RSOsPR10). To resolve this discrepancy, we checked its expression in leaves of blm and WT (S1 and S2), respectively, using gene-specific primers and reverse transcriptase-polymerase chain reaction; RSOsPR10 mRNA was found to express in the leaves.

Bystander effects are induced by CENU treatment and associated with altered protein secretory activity of treated tumor cells: a relay for chemotherapy?

In a previous study, it was reported that secondary untreated melanoma tumors implanted several weeks after and at distance from primary chloroethylnitrosourea (CENU)-treated tumors underwent differentiation and growth inhibition. To see whether the primary treated tumor released soluble factors that mediated the secondary tumor response, serum transfer experiments were performed in vivo. Administration of serum from CENU-treated tumor-bearing donors arrested tumor proliferation, decreased vessel formation and induced tumor metabolite alterations encompassing glutathione decrease and polyunsaturated fatty acid and phosphoethanolamine increase. These changes mimicked secondary tumor phenotype. To reproduce the model in vitro, cell culture supernatant transfer experiments were performed. CENU-treated cell cultures showed polyploidy and reactive oxygen species (ROS) production. Cell cultures challenged by a conditioned medium of CENU-treated cells underwent growth inhibition, cytoskeleton disorders, cytokinesis retardation, metabolite alterations, glutathione decrease and phosphoethanolamine increase, without ROS elicitation. Proteomics of CENU-treated cell conditioned media revealed altered protein secretion activity by CENU-treated cells. Among de novo secreted proteins, the most expressed were phosphatidylethanolamine-binding protein (PEBP), cardiovascular heat shock protein (cHsp), Rho-associated coiled-coil forming kinase 2 (ROCK) and actin fragments. These proteins testified of cytoskeleton disorders, growth inhibition and metabolite alterations. This article demonstrates the release by CENU-treated tumors of growth inhibitory differentiation-inducing soluble factors. These factors mediate remote bystander effects and attest persistent biological activity of residual tumors after chemotherapy.

Heat shock proteins form part of a danger signal cascade in response to lipopolysaccharide and GroEL

An increasing number of cell types, including peripheral blood mononuclear cells (PBMCs), have been demonstrated to release heat shock proteins (Hsps). In this paper we investigate further the hypothesis that Hsps are danger signals. PBMCs and Jurkat cells released Hsp70 (0.22 and 0.7 ng/10(6) cells, respectively) into medium over 24 h at 37 degrees C. Release of Hsp70 was stimulated 10-fold by GroEL (P < 0.001) and more than threefold by lipopolysaccharide (LPS) (P < 0.001). Although Hsp60 could be detected in the medium of cells cultured at 37 degrees C for 24 h, the low rates of release were due probably to cell damage. Significant release of Hsp60 was observed when Jurkat cells were exposed to GroEL (2.88 ng/10(6) cells) or LPS (1.40 ng/10(6) cells). The data are consistent with the hypothesis that Hsp70 and Hsp60 are part of a danger signalling cascade in response to bacterial infection.

AtHsfA2 modulates expression of stress responsive genes and enhances tolerance to heat and oxidative stress in Arabidopsis

There is increasing evidence for considerable interlinking between the responses to heat stress and oxidative stress, and recent researches suggest heat shock transcription factors (Hsfs) play an important role in linking heat shock with oxidative stress signals. In this paper, we present evidence that AtHsfA2 modulated expression of stress responsive genes and enhanced tolerance to heat and oxidative stress in Arabidopsis. Using Northern blot and quantitative RT-PCR analysis, we demonstrated that the expression of AtHsfA2 was induced by not only HS but also oxidative stress. By functional analysis of AtHsfA2 knockout mutants and AtHsfA2 overexpressing transgenic plants, we also demonstrated that the mutants displayed reduced the basal and acquired thermotolerance as well as oxidative stress tolerance but the overexpression lines displayed increased tolerance to these stress. The phenotypes correlated with the expression of some Hsps and APX1, ion leakage, H202 level and degree of oxidative injuries. These results showed that, by modulated expression of stress responsive genes, AtHsfA2 enhanced tolerance to heat and oxidative stress in Arabidopsis. So we suggest that AtHsfA2 plays an important role in linking heat shock with oxidative stress signals.

Localization of CD44 and hyaluronan in the synovial membrane of the rat temporomandibular joint

Previous studies have pointed out a lack of adhesion structures in the synovial lining layer of the rat temporomandibular joint (TMJ) despite showing an epithelial arrangement. CD44, a major cell adhesion molecule, plays crucial roles as an anchor between cells and extracellular matrices by binding hyaluronan (HA) for the development of organs or the metastasis of tumors. The present study examined the localization of CD44 in the synovial membrane of the rat TMJ by immunocytochemistry for OX50, ED1, and Hsp25, which are markers for the rat CD44, macrophage-like type A, and fibroblast-like type B synoviocytes, respectively. Histochemistry for HA-binding protein (HABP) was also employed for the detection of HA. OX50 immunoreactions were found along the cell surface and, in particular, accumulated along the surface of the articular cavity. Observations by a double immunostaining and immunoelectron microscopy revealed that all the OX50-immunopositive cells were categorized as fibroblastic type B cells, which had many caveolae and a few vesicles reactive to intense OX50. However, the macrophage-like type A cells did not have any OX50 immunoreaction in the synovial lining layer. A strong HABP reaction was discernable in the extracellular matrix surrounding both OX50-positive and -negative cells in the synovial lining layers, exhibiting a meshwork distribution, but weak in its sublining layer. This localization pattern of CD44 and HABP might be involved in the formation of the epithelial arrangement of the synovial lining layer. Furthermore, OX50 immunonegativity in the type A cells suggests their low phagocytotic activity in the rat TMJ under normal conditions.

Alcohol alters skeletal muscle heat shock protein gene expression in rats: these effects are moderated by sex, raised endogenous acetaldehyde, and starvation

Alcoholic myopathy is a common pathology characterized by wasting due to reduced protein synthesis, although the mechanisms involved remain unclear. Women are particularly sensitive and malnutrition exacerbates the myopathy. This study aimed to address (i) whether long-term alcohol feeding alters expression of heat shock proteins (HSPs) in male and female rats; (ii) the effect of immediate alcohol dosing with or without raised levels of endogenous acetaldehyde; and (iii) the effect of starvation. To address this, (i) male and female rats were fed alcohol in the long-term (6-7 weeks as 35% of energy in a liquid diet) and compared to controls fed the same diet with isoenergetic glucose; (ii) male rats given an immediate bolus (75 mmol ethanol per kilogram body weight intraperitoneally) 2.5 hours before sacrifice and compared to controls given a dose of saline (with or without pretreatment with cyanamide-an acetaldehyde dehydrogenase inhibitor which raises endogenous acetaldehyde); (iii) male rats starved for 1 or 2 days then immediately dosed with alcohol. Protein levels of HSP 27, HSP 60, and HSP 70 were measured in muscles of male rats fed alcohol and pair-fed control rats by SDS-PAGE and Western blotting in study I. Levels of HSP 27, HSP 60, HSP 70, and HSP 90 mRNA were analyzed in hind limb skeletal muscle by reverse transcription-polymerase chain reaction with an endogenous internal standard, glyceraldehyde-3-phosphate-dehydrogenase. (i) Long-term alcohol dosage reduced HSP 27 in male rats but not in females, whereas HSP 90 mRNA increased in long-term alcohol-fed female rats but not in male rats. These changes were reflected by a similar trend in HSP protein content, although statistical significance was not achieved. (ii) There was no effect on any of the HSP mRNAs in rats dosed immediately with alcohol or in combination with cyanamide. (iii) Starvation per se for 2 days was associated with an increase in HSP 27 mRNA. Alcohol administration after 2 days starvation caused a blunting of the increased HSP 27 mRNA in starvation alone. This suggests that long-term alcohol exposure affects HSP gene expression and that this effect is moderated by sex and starvation. This may contribute to, or reflect, the biochemical lesion in alcoholic myopathy.

Mitochondrial chaperones in cancer: from molecular biology to clinical diagnostics

Mitochondria are cell organelles involved in processes of cell life and death, and therefore also in tumoral transformation. Indeed, mitochondria dysfunction is a prominent feature of cancer cells. Mitochondrial proteins and DNA have also been previously studied as markers of tumorigenesis. Heat shock proteins (HSPs) are ubiquitous evolutionary conserved proteins. HSPs enhance their expression in stressed cells and they are involved in gene expression regulation, DNA replication, signal transduction, differentiation, apoptosis, cellular senescence or immortalization. This review reflects recent views on the role of some mitochondrial molecular chaperones as prohibitin, mortalin and HSP60/HSP10 complex and their modifications leading to cell transformation and cancer development. These molecules could represent modern molecular biomarkers for oncological management.

Genistein induces glucose-regulated protein 78 in mammary tumor cells

Preliminary studies have shown that genistein modulates the expression of some heat shock proteins in mammary tumor cells. In this study, we investigated the effect of genistein pretreatment on the expression of glucose-regulated protein 78 (GRP78) in both estrogen receptor-positive (MCF-7) and -negative (MDA-MB-231) cells. Genistein increased the expression of GRP78 in a dose- and time-dependent manner and suppressed glucose uptake in both cell lines. However, induction of GRP78 by genistein appears not to be directly associated with inhibition of glucose uptake. Genistein treatment also made MDA-MB-231 cells more sensitive to doxorubicin, probably via increased GRP78 expression, but had no effect or even decreased drug sensitivity in MCF-7 cells. These results suggest that genistein may be exploited as an enhancer of chemotherapeutic agents in certain types of breast cancer.

Microarray Gene Expression Profiling of a Human Glioblastoma Cell Line ExposedIn Vitroto a 1.9 GHz Pulse-Modulated Radiofrequency Field

The widespread use of mobile phones has led to public concerns about the health effects associated with exposure to radiofrequency (RF) fields. The paramount concern of most persons relates to the potential of these fields to cause cancer. Unlike ionizing radiation, RF fields used for mobile telecommunications (800-1900 MHz) do not possess sufficient energy to directly damage DNA. Most rodent bioassay and in vitro genotoxicity/mutation studies have reported that RF fields at non-thermal levels have no direct mutagenic, genotoxic or carcinogenic effects. However, some evidence has suggested that RF fields may cause detectable postexposure changes in gene expression. Therefore, the purpose of this study was to assess the ability of exposure to a 1.9 GHz pulse-modulated RF field for 4 h at specific absorption rates (SARs) of 0.1, 1.0 and 10.0 W/kg to affect global gene expression in U87MG glioblastoma cells. We found no evidence that non-thermal RF fields can affect gene expression in cultured U87MG cells relative to the nonirradiated control groups, whereas exposure to heat shock at 43 degrees C for 1 h up-regulated a number of typical stress-responsive genes in the positive control group. Future studies will assess the effect of RF fields on other cell lines and on gene expression in the mouse brain after in vivo exposure.

Response of the Mediterranean sponge Chondrosia reniformis Nardo to copper pollution

We examined the effects of exposure to copper pollution on the Atlanto-Mediterranean sponge Chondrosia reniformis. We transplanted sponges from an unpolluted control area to a harbour with a moderately high concentration of copper and measured several biological sponge variables. No effect of this habitat was detected on sponge growth, shape, heat-shock protein expression or metal accumulation. However, a decrease in the clearance rate, an increase in the collagen/cell rate (due to a decrease in the cellular components) and a lower survival rate after 4 months of the sponges transplanted to the harbour was observed. We suggest that copper may alter the sponge physiology, by reducing pumping capacity, which may ultimately lead to sponge death. Consequently, copper pollution exerts strong negative effects on this organism.

[Analysis of changes about hsbp1, hsf1, hsf2 AND hsp70's expression levels in rat's regenerating liver]

Heat shock factor binding protein 1 (HSBP1), a recently discovered protein, weakens and blocks transcription of the heat shock protein 70 (HSP70) gene when binding to HSF1, but HSBP1 can promote cell growth, cell development and cell differentiation when binding to HSF2. Partial hepatectomy (PH) in rat creates injury stimulation and induces liver regeneration. How does hsbp1 coordinate two processes sequently is extremely interesting. This paper, based on cloning the full-length cDNA of hsbpl in rat, applied in situ hybridration and Rat Genome 230 2.0 Array to analyze hsbp1, hsf1, hsf2 and hsp70 expression in liver after PH and sham-operation. The results indicated that the hsbp1 expression level was down-regulated meaningfully at 0.5-2h and up-regulated meaningfully at 8-16h after sham-operation, while hsf2 expression level did not meaningfully change at 0-144h after sham-operation. hsbp1 expression level was up-regulated meaningfully at 6h and 66-144h,and hsf1 at 8-16h, hsf2 at 2-16h, hsp70 at 0.5-24h after PH. Our data suggested that up-regulated expression of the hsp70 at 0.5-12h after sham-operation was controlled by intracellular HSF1, and then controlled by hsbp1 down-regulated at 0.5-2h and hsf1 up-regulated at 8-16h. In the early phase of liver regeneration in rats, hsbp1 and hsf2 expression levels were up-regulated, which promoted cell proliferation through HSBP1 and HSF2 up-regulating,upa activating,c-jun enhancing, intracellular matrix (ECM) degradation, activating the hepatocyte-like growth factor (HGF) etc. In the late phase of liver regeneration (66-144h), hsbp1 expression level was up-regulated, which promoted reconstruction of liver structure and recovery of liver function through HSBP1 inhibiting hsp70 expression, up-regulating genes related to growth, development, differentiation. In conclusion, down-regulating of hsbp1 contributed to interaction between HSF1 and HSE,increased hsp70 expression and enhanced anti-injured capacity of liver and rats. HSBP1 and HSF2 activated the genes related to growth, development, differentiation and then promoted liver regeneration in rats.

[Stress proteins of Bifidobacterium longum NCC2705]

Stress proteins of Bifidobacterium longum strain NCC2705 were identified and characterized during stationary phase. According to the proteomic map of L. lactics IL1403 and theoretical Mr/pl of stress proteins in B. longum NCC2705 genome annotation, spots of stress proteins in gels were localized, and proteins were identified by matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) and/or ESI-MS/MS mass spectrometry. For protein identification by peptide mass fingerprinting, peptide masses were searched against database of B. longum NCC2705 by Mascot licensed in-house. 44 spots representing 8 protein entries have been identified, these proteins were hydrophilic proteins and predicted acid proteins. Spot and protein analysis revealed that post-translational modifications might be common in these proteins. Except for DnaJ, the stress proteins were encoded by genes with CAI value above 0.5, and represented a large proportion of the most abundant proteins. Moreover, the results of scavenging effects on free radicals in vitro showed that B. longum NCC2705 can inhibit fatty acid oxidation and scavenge DPPH, but they scavenge weakly active oxygen free radicals. We identified a key protein that can reverse oxidative damage to proteins and lipids: alkyl hydroperoxide reductase (ahpC, BL0615)synthesized under our experimental conditions.

Analysis of candidate genes through a proteomics-based approach in primary cell lines from malignant melanomas and their metastases

Proteomics provides a powerful approach for screening alterations in protein expression and post-translational modification associated with particular human diseases. In this study, the analysis of protein expression was focused on malignant melanoma in order to determine the candidate genes involved in tumour progression. The proteomes of cultured melanocytes and of cell lines from primary and metastatic lesions of one malignant melanoma patient were profiled using two-dimensional electrophoresis (2-DE) and mass spectrometry. Differentially expressed proteins were confirmed by 2-DE and mass spectrometry on an additional four malignant melanoma cell lines. Total RNA from the first subset of cell lines was used for quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) of the candidate genes identified after proteomics analysis. A very high similarity was observed in the 2-DE maps of two malignant melanoma cell lines derived from primary and secondary lesions of the same patient. Mass spectrometry identified 37 proteins which were found to be more abundant in tumour cells in comparison with control melanocytes (as confirmed on additional cell lines), with a relatively high prevalence of stress proteins. Eight candidate genes (PRDX2, HSP27, HSP60, HSPA8, HSP9B, STIP1, PDI and P4HB) were further characterized by evaluating their messenger RNA expression levels through real-time RT-PCR analysis. Overexpression of HSP27, HSP60 and HSPA8 and downregulation of PRDX2 were observed in cells from metastatic malignant melanoma in comparison with those from primary melanoma. Although further investigations with larger numbers of paired normal and tumour samples are needed, our findings strongly suggest that the dysregulation of stress pathways may be involved in melanoma progression.

Isolation and characterization of synovial cells from the human temporomandibular joint

BACKGROUND

The synovial tissues with temporomandibular disorders (TMDs) often show chronic inflammatory changes and the synovial cells participate in the pathogenic processes of TMDs. The synovial membrane is composed of a synovial lining layer and a connective sublining layer. The synovial lining layer is made up of two kinds of cells: macrophage-like type A and fibroblastic type B cells. The aim of this study was to isolate and characterize synovial cells from the human temporomandibular joint (TMJ).

METHODS

Synovial cells were isolated using an explant culture method. Then, we characterized the cultured synovial cells (SGA2 cells) using immunocytochemistry.

RESULTS

SGA2 cells expressed the fibroblastic markers vimentin and prolyl 4-hydroxylase; they also expressed laminin and heat shock protein 27, all of which are markers of type B cells. However, some cells expressed the macrophage marker CD68. These CD68-positive cells simultaneously expressed laminin.

CONCLUSIONS

We isolated and cultured synovial type B cells from the human TMJ, and identified the presence of intermediate type synovial lining cells, having the phenotypic properties of both type A and type B cells, among the synovial lining cells.

High glucose concentration induces elevated expression of anti-oxidant and proteolytic enzymes in cultured human retinal pigment epithelial cells

We investigated the differential protein expression patterns of retinal pigment epithelial (RPE) cells exposed to increased glucose concentrations. Cultured human RPE cells (ARPE-19) were exposed for 4 days with normal blood glucose concentration (5.5 mM D-glucose), followed by exposure to either normal (5.5 mM) or high (33 mM) concentrations of D-glucose for 48h. Protein extracts of glucose-treated RPE cells were then subjected to comparative proteome analysis based on 2-D gel electrophoresis. Protein spots were visualized by silver staining. The differentially expressed proteins were excised and digested in-gel with trypsin, then analysed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The expression levels of cathepsin B, glutathione peroxidase and heat shock protein 27 were increased, and that of protein disulfide isomerase decreased in high glucose treated RPE compared to normal glucose. The isoelectric point of copper/zinc-containing superoxide dismutase (Cu/Zn-SOD) shifted toward acidic region in response to high glucose. Cu/Zn-SOD activity in high glucose group was significantly lower than that in normal glucose group (P<0.05, Mann-Whitney U-test). Systematic survey of protein expression has revealed that RPE cells respond to acute, pathologically high glucose levels by the elevated expression of anti-oxidant and proteolytic enzymes.

The ExPortal: an organelle dedicated to the biogenesis of secreted proteins in Streptococcus pyogenes

The Gram-positive pathogen Streptococcus pyogenes secretes proteins through the ExPortal, a unique single microdomain of the cellular membrane specialized to contain the Sec translocons. It has been proposed that the ExPortal functions as an organelle to promote the biogenesis of secreted proteins by coordinating interactions between nascent unfolded secretory proteins and membrane-associated chaperones. In this study we provide evidence to support this model. It was found that HtrA (DegP), a surface anchored accessory factor required for maturation of the secreted SpeB cysteine protease, was localized exclusively to the ExPortal. Furthermore, the ATP synthase beta subunit was not localized to the ExPortal, suggesting that retention is likely restricted to a specific subset of exported proteins. Mutations that disrupted the anchoring, but not the protease activity, of HtrA, also altered the maturation kinetics of SpeB demonstrating that localization to the ExPortal was important for HtrA function. These data indicate that the ExPortal provides a mechanism by which Gram-positive bacteria can coordinate protein secretion and subsequent biogenesis in the absence of a specialized protein-folding compartment.

Identification and characterization of a stress-inducible and a constitutive small heat-shock protein targeted to the matrix of plant peroxisomes

Small heat-shock proteins (sHsps) are widespread molecular chaperones for which a peroxisomal localization has not yet been reported. The Arabidopsis (Arabidopsis thaliana) genome encodes two sHsps with putative peroxisomal targeting signals type 1 or 2 (PTS1 or PTS2). As demonstrated by double-labeling experiments using full-length fusion proteins with enhanced yellow fluorescent protein and deletion constructs lacking the putative targeting domains, AtHsp15.7 (At5g37670) and AtAcd31.2 (At1g06460) are targeted to the peroxisome matrix by a functional PTS1 (SKL>) and a functional PTS2 (RLx5HF), respectively. The peroxisomal localization of AtAcd31.2 was further confirmed by isolation of leaf peroxisomes from Arabidopsis by two successive sucrose density gradients, protein separation by one- and two-dimensional gel electrophoresis, and mass spectrometric protein identification. When AtHsp15.7 and AtAcd31.2 were heterologously expressed in yeast (Saccharomyces cerevisiae) and directed to the cytosol by deletion of the PTSs, both sHsps were able to complement the morphological phenotype of yeast mutants deficient in the cytosolic homologs ScHsp42 or ScHsp26. According to expression studies by reverse transcription-PCR, AtAcd31.2 is constitutively expressed, whereas AtHsp15.7 is hardly expressed under normal conditions but strongly induced by heat and oxidative stress, the latter of which was triggered by the catalase inhibitor 3-aminotriazole or the herbicide methyl viologen applied by watering of whole plants or infiltration of rosette leaves. Thus, plants are exceptional among eukaryotes in employing sHsps in the peroxisome matrix to prevent unspecific aggregation of partially denatured proteins under both physiological and stress conditions.

An immunohistochemical study of the expression of heat-shock protein-25 and cell proliferation in the dental pulp and enamel organ during odontogenesis in rat molars

OBJECTIVES

The aim of this study is to clarify the functional significance of heat-shock protein (HSP)-25 during tooth development.

DESIGN

We compared the expression of HSP-25 in the dental epithelial and mesenchymal cells with their proliferative activity during odontogenesis in rat molars on postnatal days 1-100 by immunohistochemistry using anti-HSP-25 and anti-5-bromo-2'-deoxyuridine (BrdU) for cell proliferation assay.

RESULTS

On day 1, BrdU-immunoreactive cells were densely located in the inner enamel epithelium in the cervical loop and intercusped areas and the dental pulp adjacent to them, whereas HSP-25-immunoractivity (IR) was restricted to the cusped area where odontoblasts and ameloblasts had already differentiated. Subsequently, BrdU-IR shifted in the apical direction to be localized around Hertwig's epithelial root sheath during days 5-30, never overlapping with concomitantly apically-shifted HSP-25-IR. On days 60-100, BrdU-immunoreactive cells were hardly recognizable in the dental pulp, where HSP-25-IR was exclusively localized in the odontoblast layer. Furthermore, the odontoblast- and ameloblast-lineage cells exhibited two steps in the expression of HSP-25 throughout the postnatal stages: first, dental epithelial and pulpal mesenchymal cells showed a weak IR for HSP-25 after the cessation of their proliferative activity, and subsequently odontoblasts and ameloblasts consistently expressed an intense HSP-25-IR.

CONCLUSION

Odontoblast- and ameloblast-lineage cells acquire HSP-25-IR after they complete their cell division, suggesting that this protein acts as a switch between cell proliferation and differentiation during tooth development. The consistent expression of HSP-25-IR in the formative cells may be involved in the maintenance of their functional integrity.