OP0024 DECREASED LEVELS OF T FOLLICULAR HELPER (CD4+CXCR5+) CELLS AND CD27+CD38+ AND CD27+CD38- B CELLS IN ANKYLOSING SPONDYLITIS PATIENTS CORRELATE WITH MARKER OF INFLAMMATION

Background:

The role of different lymphocyte subsets in ankylosing spondylitis (AS) is still to be elucidated. It has previously been reported contradictory data concerning the levels of T Follicular Helper (TFH) cells and differentiated B cells in peripheral blood of AS patients. In addition, the connection to disease related parameters is still to be fully revealed.

Objectives:

The purpose of this study was to investigate the level of CD4+TFH cells and CD27+CD38+/CD38- B cells in patients with AS from northern Sweden and to compare the levels with age and sex-matched controls. We also studied associations between these cell subsets and disease related factors.

Methods:

Peripheral blood mononuclear cells (PBMSc) from a cohort of 50 patients with AS from Region Västerbotten (mean age 52±9.1 years, 33 (66 %) men, 50 (100 %) HLAB27 positive) and 50 pair wise matched blood donor controls (mean age 54±8.8 years, 33 (66 %) men) were stained with a combination of antibodies allowing for the detection of CD27, CD38, CD19, CD3, CD4 and CXCR5 markers and analyzed by flow cytometry. In addition, the patient with AS were examined with spinal x-ray for radiographic alterations assessed with mSASSS. CRP and ESR were measured and physical function and disease activity were registered with BASMI and BASFI respectively ASDAS-CRP and BASDAI.

Results:

When comparing AS patients and controls pair wise, we observed on average a 50% reduction of TFH (CD3+CD4+CXCR5+) cells among CD45+ lymphocytes in PBMCs from patients (p=0,000008). Furthermore, a 20-30% reduction among memory/plasma cells (CD19+CD27+CD38+ and CD19+CD27+CD38-) among CD45+ lymphocytes in PBMCs from patients (p=0,002 and p=0,007 respectively). For female patients a correlation between TFH and ESR (Rs=-0,551 p=0,022) was observed. Moreover, negative correlations between the two B cell subsets (CD19+CD27+CD38+ and CD19+CD27+CD38-) and ESR were observed for female patients (Rs =–0,476 p=0,053 and Rs =–0,522 p=0,032 respectively).

Conclusion:

TFH cells was reduced in AS patients and this reduction correlated with a reduction in differentiated (CD27+CD38+ and CD27+CD38-) B cells. In addition, the inflammation marker ESR was negatively correlated with TFH as well as with the differentiated B cell subsets in female patients. Our observations indicates a role of the humoral immune response in AS.

Disclosure of Interests:

None declared

Hyaluronan concentration and molecular mass in psoriatic arthritis: biomarkers of disease severity, resistance to treatment, and outcome

Objective: Low molecular mass hyaluronan causes inflammatory processes and can act as a pro-inflammatory cytokine in skin and other sites of activity in psoriatic arthritis (PsA). This study investigated whether the molecular mass distribution of hyaluronan (HA) in skin and the quantity of circulating HA are related to the clinical inflammatory picture in PsA with active disease and to the effect of treatment with anti-tumour necrosis factor-α (anti-TNF-α) adalimumab. Methods: Twenty patients with TNF-α-naïve active polyarticular PsA were included in this prospective clinical trial of treatment with 40 mg s.c. adalimumab according to standard procedure. Clinical activity, patients' assessments, and skin biopsies were captured at inclusion and at the 12 week follow-up. Ten healthy individuals were recruited for comparison of HA analyses. Histochemistry of skin inflammation, serum HA, and molecular mass of HA were determined. Results: Overall improvements in clinical parameters were observed. Eight of 18 patients reached minimum disease activity after 12 weeks and disease activity was significantly reduced (p < 0.0001). Patients with elevated serum HA values were significantly older, had later onset of arthritis and more deformed joints, still had swollen joints after treatment, and had more circulating inflammatory biomarkers. More severe disease pathology showed a wide spectrum of high-molecular-mass HA accompanied by low mass HA. The treatment appears partly to normalize the HA mass distribution. Conclusion: HA concentration and mass seem to be two possible factors in the inflammatory pathology of PsA acting as biomarkers for disease severity, resistance to treatment, and worse outcome.

Cyclin-dependent kinase 5 mediates pleiotrophin-induced endothelial cell migration

Pleiotrophin (PTN) stimulates endothelial cell migration through binding to receptor protein tyrosine phosphatase beta/zeta (RPTPβ/ζ) and α_νβ₃ integrin. Screening for proteins that interact with RPTPβ/ζ and potentially regulate PTN signaling, through mass spectrometry analysis, identified cyclin-dependent kinase 5 (CDK5) activator p35 among the proteins displaying high sequence coverage. Interaction of p35 with the serine/threonine kinase CDK5 leads to CDK5 activation, known to be implicated in cell migration. Protein immunoprecipitation and proximity ligation assays verified p35-RPTPβ/ζ interaction and revealed the molecular association of CDK5 and RPTPβ/ζ. In endothelial cells, PTN activates CDK5 in an RPTPβ/ζ- and phosphoinositide 3-kinase (PI3K)-dependent manner. On the other hand, c-Src, α_νβ₃ and ERK1/2 do not mediate the PTN-induced CDK5 activation. Pharmacological and genetic inhibition of CDK5 abolished PTN-induced endothelial cell migration, suggesting that CDK5 mediates PTN stimulatory effect. A new pyrrolo[2,3-α]carbazole derivative previously identified as a CDK1 inhibitor, was found to suppress CDK5 activity and eliminate PTN stimulatory effect on cell migration, warranting its further evaluation as a new CDK5 inhibitor. Collectively, our data reveal that CDK5 is activated by PTN, in an RPTPβ/ζ-dependent manner, regulates PTN-induced cell migration and is an attractive target for the inhibition of PTN pro-angiogenic properties.

The 1p36 Tumor Suppressor KIF 1Bβ Is Required for Calcineurin Activation, Controlling Mitochondrial Fission and Apoptosis

KIF1Bβ is a candidate 1p36 tumor suppressor that regulates apoptosis in the developing sympathetic nervous system. We found that KIF1Bβ activates the Ca(2+)-dependent phosphatase calcineurin (CN) by stabilizing the CN-calmodulin complex, relieving enzymatic autoinhibition and enabling CN substrate recognition. CN is the key mediator of cellular responses to Ca(2+) signals and its deregulation is implicated in cancer, cardiac, neurodegenerative, and immune disease. We show that KIF1Bβ affects mitochondrial dynamics through CN-dependent dephosphorylation of Dynamin-related protein 1 (DRP1), causing mitochondrial fission and apoptosis. Furthermore, KIF1Bβ actuates recognition of all known CN substrates, implying a general mechanism for KIF1Bβ in Ca(2+) signaling and how Ca(2+)-dependent signaling is executed by CN. Pathogenic KIF1Bβ mutations previously identified in neuroblastomas and pheochromocytomas all fail to activate CN or stimulate DRP1 dephosphorylation. Importantly, KIF1Bβ and DRP1 are silenced in 1p36 hemizygous-deleted neuroblastomas, indicating that deregulation of calcineurin and mitochondrial dynamics contributes to high-risk and poor-prognosis neuroblastoma.

Proteomics analysis of Echinococcus granulosus protoscolex stage

Echinococcus granulosus protoscolex proteins were separated using two-dimensional electrophoresis and then identified using mass spectrometry; we identified 61 proteins, 28 which are newly described of which 4 could be involved in hydatid cyst fertility molecular mechanisms.

The conserved Trp114 residue of thioredoxin reductase 1 has a redox sensor-like function triggering oligomerization and crosslinking upon oxidative stress related to cell death

The selenoprotein thioredoxin reductase 1 (TrxR1) has several key roles in cellular redox systems and reductive pathways. Here we discovered that an evolutionarily conserved and surface-exposed tryptophan residue of the enzyme (Trp114) is excessively reactive to oxidation and exerts regulatory functions. The results indicate that it serves as an electron relay communicating with the FAD moiety of the enzyme, and, when oxidized, it facilitates oligomerization of TrxR1 into tetramers and higher multimers of dimers. A covalent link can also be formed between two oxidized Trp114 residues of two subunits from two separate TrxR1 dimers, as found both in cell extracts and in a crystal structure of tetrameric TrxR1. Formation of covalently linked TrxR1 subunits became exaggerated in cells on treatment with the pro-oxidant p53-reactivating anticancer compound RITA, in direct correlation with triggering of a cell death that could be prevented by antioxidant treatment. These results collectively suggest that Trp114 of TrxR1 serves a function reminiscent of an irreversible sensor for excessive oxidation, thereby presenting a previously unrecognized level of regulation of TrxR1 function in relation to cellular redox state and cell death induction.

Human protein kinase CK2 phosphorylates matrix metalloproteinase 2 and inhibits its activity

Matrix metalloproteinase 2 (MMP-2) is involved in cancer development and is overexpressed in a variety of malignant tumors. MMP-2 activity is controlled mainly by transcription, proteolytic activation, and inhibition by endogenous inhibitors. It had previously been demonstrated that MMP-2 activity is also regulated by phosphorylation at several sites by protein kinase C. Here we demonstrate, by means of bioinformatics and biochemical and cellular assays, that protein kinase CK2 also acts as a modulator of MMP-2 activity. CK2 down-regulates MMP-2 in vitro, and inhibition of CK2 in human fibrosarcoma cells results in up-regulation of MMP-2. The discovery of the crosstalk between MMP-2 and CK2 opens the possibility of new combined anticancer therapies.

Association of nuclear-localized Nemo-like kinase with heat-shock protein 27 inhibits apoptosis in human breast cancer cells

Nemo-like kinase (NLK), a proline-directed serine/threonine kinase regulated by phosphorylation, can be localized in the cytosol or in the nucleus. Whether the localization of NLK can affect cell survival or cell apoptosis is yet to be disclosed. In the present study we found that NLK was mainly localized in the nuclei of breast cancer cells, in contrast to a cytosolic localization in non-cancerous breast epithelial cells. The nuclear localization of NLK was mediated through direct interaction with Heat shock protein 27 (HSP27) which further protected cancer cells from apoptosis. The present study provides evidence of a novel mechanism by which HSP27 recognizes NLK in the breast cancer cells and prevents NLK-mediated cell apoptosis.

RNA helicase A is a downstream mediator of KIF1Bβ tumor-suppressor function in neuroblastoma

Inherited KIF1B loss-of-function mutations in neuroblastomas and pheochromocytomas implicate the kinesin KIF1B as a 1p36.2 tumor suppressor. However, the mechanism of tumor suppression is unknown. We found that KIF1B isoform β (KIF1Bβ) interacts with RNA helicase A (DHX9), causing nuclear accumulation of DHX9, followed by subsequent induction of the proapoptotic XIAP-associated factor 1 (XAF1) and, consequently, apoptosis. Pheochromocytoma and neuroblastoma arise from neural crest progenitors that compete for growth factors such as nerve growth factor (NGF) during development. KIF1Bβ is required for developmental apoptosis induced by competition for NGF. We show that DHX9 is induced by and required for apoptosis stimulated by NGF deprivation. Moreover, neuroblastomas with chromosomal deletion of 1p36 exhibit loss of KIF1Bβ expression and impaired DHX9 nuclear localization, implicating the loss of DHX9 nuclear activity in neuroblastoma pathogenesis.

SIGNIFICANCE

KIF1Bβ has neuroblastoma tumor-suppressor properties and promotes and requires nuclear-localized DHX9 for its apoptotic function by activating XAF1 expression. Loss of KIF1Bβ alters subcellular localization of DHX9 and diminishes NGF dependence of sympathetic neurons, leading to reduced culling of neural progenitors, and, therefore, might predispose to tumor formation.

The PI3-kinase isoform p110δ is essential for cell transformation induced by the D816V mutant of c-Kit in a lipid-kinase-independent manner

PI3-kinase has a crucial role in transformation mediated by the oncogenic c-Kit mutant D816V. In this study, we demonstrate that the c-Kit/D816V-mediated cell survival is dependent on an intact direct binding of PI3-kinase to c-Kit. However, mutation of this binding site had little effect on the PI3-kinase activity in the cells, suggesting that c-Kit/D816V-mediated cell survival is dependent on PI3-kinase but not its kinase activity. Furthermore, inhibition of the lipid kinase activity of PI3-kinase led only to a slight inhibition of cell survival. Knockdown of the predominant PI3-kinase isoform p110δ in c-Kit/D816V-expressing Ba/F3 cells led to reduced cell transformation both in vitro and in vivo without affecting the overall PI3-kinase activity. This suggests that p110δ has a lipid-kinase-independent role in c-Kit/D816V-mediated cell transformation. We furthermore demonstrate that p110δ is phosphorylated at residues Y524 and S1039 and that phosphorylation requires an intact binding site for PI3-kinase in c-Kit/D816V. Overexpression of p110δ carrying the Y523F and S1038A mutations significantly reduced c-Kit/D816V-mediated cell survival and proliferation. Taken together, our results demonstrate an important lipid-kinase-independent role of p110δ in c-Kit/D816V-mediated cell transformation. This furthermore suggests that p110δ could be a potential diagnostic factor and selective therapeutic target for c-Kit/D816V-expressing malignancies.

ITREOH Building of Regional Capacity to Monitor Recreational Water: Development of a Non-commercial Microcystin ELISA and Its Impact on Public Health Policy

In 2001, a University of California, Davis-University of the Republic, Montevideo, partnership created a Fogarty ITREOH program to exploit the potential of ELISA to provide a low-cost environmental analysis attractive to economically distressed countries of temperate South America. This paper describes the development and validation of an ELISA method for the determination of Cyanobacteria microcystin toxins in algal blooms, which release hepatotoxic metabolites that can reach toxic levels in rivers, lakes, or coastal estuaries used for recreation or water supplies. The assay made possible the first systematic monitoring of water from the Rio de la Plata at Montevideo over two summers. The project has been integrated into a bi-national effort to monitor the Rio de la Plata.

Abstract 4301: Transformation by the D816V mutant of c-Kit is dependent on the PI3-kinase isoform p110δ but independent of its lipid kinase activi

Gain-of-function mutations of the receptor tyrosine kinase c-Kit are frequently seen in several malignanices with the D816V mutation being the most common. In this study we demonstrate that a mutant of c-Kit/D816V that is deficient in binding of the p85 subunit of PI3-kinase (M724A) has lost its ability to induce ligand-independent cell survival and proliferation while c-Kit/D816V induced PI3-kinases activity was only marginally reduced. Furthermore, inhibitors of PI3-kinase were unable to block c-Kit/D816V-induced cell survival. These data suggest that PI3-kinase plays a role in c-Kit/D816V induced cell transformation which is independent of its lipid kinase activity. By mass spectrometry, we identified a heavily tyrosine-phosphorylated 110 kDa protein associated with p85 to be the p110δ subunit of PI3-kinase and the site of phosphorylation as Tyr 523, and the phosphorylation is not dependent on the lipid kinase activity of PI3-kinase. Knockdown of p110δ in c-Kit/D816V expressing Ba/F3 cells led to reduced cell survival and proliferation while the PI3-kinase activity remained almost intact. The c-Kit/D816V expressing Ba/F3 cells lost their ability to form colonies in semi-solid culture if p110δ was knocked down. Additionally, knockdown of p110δ λεδ τo ρεδυχεδ τυμoρ σιζε, τυμoρ ωειγητ ανδ blood vessel formation ωηεν c-Kit/D816V expressing Ba/F3 cells were subcutaneously injected into nude mice. Taken together, these results suggest a kinase independent role of p110δ in the D816Vmutant of c-Kit mediated cell transformation and suggest that p110δ could potentially be a selective therapeutic target for c-Kit/D816V expressing tumors.

Citation Format: Jianmin Sun, Sofie Mohlin, Alicia Lundby, Ulf Hellman, Sven Påhlman, Jesper V. Olsen, Lars Rönnstrand. Transformation by the D816V mutant of c-Kit is dependent on the PI3-kinase isoform p110δ but independent of its lipid kinase activi. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4301. doi:10.1158/1538-7445.AM2013-4301

Boar seminal plasma exosomes: effect on sperm function and protein identification by sequencing

Mammalian seminal plasma contains membranous vesicles (exosomes), with a high content of cholesterol and sphingomyelin and a complex protein composition. Their physiological role is uncertain because sperm stabilization and activation effects have been reported. To analyze a putative modulatory role for semen exosomes on sperm activity in the boar, the effects of these vesicles on several sperm functional parameters were examined. Additionally, boar exosome proteins were sequenced and their incorporation into sperm was explored. Boar sperm were incubated under conditions that induce capacitation, manifested as increased tyrosine phosphorylation, cholesterol loss and greater fluidity in apical membranes, and the ability to undergo the lysophosphatidylcholine-induced acrosome reaction. After establishing this cluster of capacitation-dependent functional parameters, the effect produced by exosomes when present during or after sperm capacitation was analyzed. Exosomes inhibited the capacitation-dependent cholesterol efflux and fluidity increase in apical membranes, and the disappearance of a 14-kD phosphorylated polypeptide. In contrast, the acrosome reaction (spontaneous and lysophosphatidylcholine-induced) was not affected, and sperm binding to the oocyte zona pellucida was reduced only when vesicles were present during gamete coincubation. Liposomes with a lipid composition similar to that present in exosomes mimicked these effects, except the one on zona pellucida binding. Interaction between exosomes and sperm was confirmed by transfer of aminopeptidase activity. In addition, the major exosome protein, identified as actin, appeared to associate with sperm after coincubation. Exosome composition had a predominance for structural proteins (actin, plastin, ezrin, and condensin), enzymes, and several porcine seminal plasma-specific polypeptides (e.g., spermadhesins). Transfer of proteins from exosome to sperm and their ability to block cholesterol efflux supports a direct interaction between these vesicles and sperm, whereas inhibition of some capacitation-dependent features suggests a stabilizing function for exosomes in boar semen.

Interplay between αvβ3 integrin and nucleolin regulates human endothelial and glioma cell migration

The multifunctional protein nucleolin (NCL) is overexpressed on the surface of activated endothelial and tumor cells and mediates the stimulatory actions of several angiogenic growth factors, such as pleiotrophin (PTN). Because α(v)β(3) integrin is also required for PTN-induced cell migration, the aim of the present work was to study the interplay between NCL and α(v)β(3) by using biochemical, immunofluorescence, and proximity ligation assays in cells with genetically altered expression of the studied molecules. Interestingly, cell surface NCL localization was detected only in cells expressing α(v)β(3) and depended on the phosphorylation of β(3) at Tyr(773) through receptor protein-tyrosine phosphatase β/ζ (RPTPβ/ζ) and c-Src activation. Downstream of α(v)β(3,) PI3K activity mediated this phenomenon and cell surface NCL was found to interact with both α(v)β(3) and RPTPβ/ζ. Positive correlation of cell surface NCL and α(v)β(3) expression was also observed in human glioblastoma tissue arrays, and inhibition of cell migration by cell surface NCL antagonists was observed only in cells expressing α(v)β(3). Collectively, these data suggest that both expression and β(3) integrin phosphorylation at Tyr(773) determine the cell surface localization of NCL downstream of the RPTPβ/ζ/c-Src signaling cascade and can be used as a biomarker for the use of cell surface NCL antagonists as anticancer agents.

Chromosomal aneuploidy affects the global proteome equilibrium of colorectal cancer cells

BACKGROUND

Chromosomal aneuploidy has been identified as a prognostic factor in the majority of sporadic carcinomas. However, it is not known how chromosomal aneuploidy affects chromosome-specific protein expression in particular, and the cellular proteome equilibrium in general.

OBJECTIVE

The aim was to detect chromosomal aneuploidy-associated expression changes in cell clones carrying trisomies found in colorectal cancer.

METHODS

We used microcell-mediated chromosomal transfer to generate three artificial trisomic cell clones of the karyotypically stable, diploid, yet mismatch-deficient, colorectal cancer cell line DLD1--each of them harboring one extra copy of either chromosome 3, 7 or 13. Protein expression differences were assessed by two-dimensional gel electrophoresis and mass spectrometry, compared to whole-genome gene expression data, and evaluated by PANTHER classification system and Ingenuity Pathway Analysis (IPA).

RESULTS

In total, 79 differentially expressed proteins were identified between the trisomic clones and the parental cell line. Up-regulation of PCNA and HMGB1 as well as down-regulation of IDH3A and PSMB3 were revealed as trisomy-associated alterations involved in regulating genome stability.

CONCLUSIONS

These results show that trisomies affect the expression of genes and proteins that are not necessarily located on the trisomic chromosome, but reflect a pathway-related alteration of the cellular equilibrium.

PKCα binds G3BP2 and regulates stress granule formation following cellular stress

Protein kinase C (PKC) isoforms regulate a number of processes crucial for the fate of a cell. In this study we identify previously unrecognized interaction partners of PKCα and a novel role for PKCα in the regulation of stress granule formation during cellular stress. Three RNA-binding proteins, cytoplasmic poly(A)(+) binding protein (PABPC1), IGF-II mRNA binding protein 3 (IGF2BP3), and RasGAP binding protein 2 (G3BP2) all co-precipitate with PKCα. RNase treatment abolished the association with IGF2BP3 and PABPC1 whereas the PKCα-G3BP2 interaction was largely resistant to this. Furthermore, interactions between recombinant PKCα and G3BP2 indicated that the interaction is direct and PKCα can phosphorylate G3BP2 in vitro. The binding is mediated via the regulatory domain of PKCα and the C-terminal RNA-binding domain of G3BP2. Both proteins relocate to and co-localize in stress granules, but not to P-bodies, when cells are subjected to stress. Heat shock-induced stress granule assembly and phosphorylation of eIF2α are suppressed following downregulation of PKCα by siRNA. In conclusion this study identifies novel interaction partners of PKCα and a novel role for PKCα in regulation of stress granules.

Proteomic profiling of follicular and papillary thyroid tumors

OBJECTIVE

Thyroid proteomics is a new direction in thyroid cancer research aiming at etiological understanding and biomarker identification for improved diagnosis.

METHODS

Two-dimensional electrophoresis was applied to cytosolic protein extracts from frozen thyroid samples (ten follicular adenomas, nine follicular carcinomas, ten papillary carcinomas, and ten reference thyroids). Spots with differential expression were revealed by image and multivariate statistical analyses, and identified by mass spectrometry.

RESULTS

A set of 25 protein spots significant for discriminating between the sample groups was identified. Proteins identified for nine of these spots were studied further including 14-3-3 protein beta/alpha, epsilon, and zeta/delta, peroxiredoxin 6, selenium-binding protein 1, protein disulfide-isomerase precursor, annexin A5 (ANXA5), tubulin alpha-1B chain, and α1-antitrypsin precursor. This subset of protein spots carried the same predictive power in differentiating between follicular carcinoma and adenoma or between follicular and papillary carcinoma, as compared with the larger set of 25 spots. Protein expression in the sample groups was demonstrated by western blot analyses. For ANXA5 and the 14-3-3 proteins, expression in tumor cell cytoplasm was demonstrated by immunohistochemistry both in the sample groups and an independent series of papillary thyroid carcinomas.

CONCLUSION

The proteins identified confirm previous findings in thyroid proteomics, and suggest additional proteins as dysregulated in thyroid tumors.

Identification of a novel protein kinase Cδ-Smac complex that dissociates during paclitaxel-induced cell death

Protein kinase C (PKC) δ is a regulator of apoptosis with both pro- and anti-apoptotic effects. The mechanistic basis for the discrepant effects is not completely understood. Here we show that Smac interacts with PKCδ. The interaction depends on the N-terminus of Smac and is disrupted upon treatment with paclitaxel. This is associated with release of Smac into the cytosol. Activation of PKCδ rescues the interaction during paclitaxel exposure and suppresses the paclitaxel-mediated cell death. However, under these conditions the complex is mainly found in the cytosol suggesting that cytosolic Smac can be bound by PKCδ when PKC is activated. The data unravel a previously unrecognized interaction and suggest that PKCδ by associating with Smac may prevent its apoptotic effects.

Amidoxime reductase system containing cytochrome b5 type B (CYB5B) and MOSC2 is of importance for lipid synthesis in adipocyte mitochondria

Reduction of hydroxylamines and amidoximes is important for drug activation and detoxification of aromatic and heterocyclic amines. Such a reductase system was previously found to be of high activity in adipose tissue and liver, and furthermore, in vitro studies using recombinant truncated and purified enzymes suggested the participation of cytochrome b(5) reductase (CYB5R), cytochrome b(5) (CYB5), and molybdenum cofactor sulfurase C-terminal containing 1 and 2 (MOSC1 and -2). Here, we show that purified rat liver outer mitochondrial membrane contains high amidoxime reductase activity and that MOSC2 is exclusively localized to these membranes. Moreover, using the same membrane fraction, we could show direct binding of a radiolabeled benzamidoxime substrate to MOSC2. Following differentiation of murine 3T3-L1 cells into mature adipocytes, the MOSC2 levels as well as the amidoxime reductase activity were increased, indicating that the enzyme is highly regulated under lipogenic conditions. siRNA-mediated down-regulation of MOSC2 and the mitochondrial form of cytochrome b(5) type B (CYB5B) significantly inhibited the reductase activity in the differentiated adipocytes, whereas down-regulation of MOSC1, cytochrome b(5) type A (CYB5A), CYB5R1, CYB5R2, or CYB5R3 had no effect. Down-regulation of MOSC2 caused impaired lipid synthesis. These results demonstrate for the first time the direct involvement of MOSC2 and CYB5B in the amidoxime reductase activity in an intact cell system. We postulate the presence of a novel reductive enzyme system of importance for lipid synthesis that is exclusively localized to the outer mitochondrial membrane and is composed of CYB5B, MOSC2, and a third unknown component (a CYB5B reductase).

Essential role for DNA-PK-mediated phosphorylation of NR4A nuclear orphan receptors in DNA double-strand break repair

DNA-dependent protein kinase (DNA-PK) is a central regulator of DNA double-strand break (DSB) repair; however, the identity of relevant DNA-PK substrates has remained elusive. NR4A nuclear orphan receptors function as sequence-specific DNA-binding transcription factors that participate in adaptive and stress-related cell responses. We show here that NR4A proteins interact with the DNA-PK catalytic subunit and, upon exposure to DNA damage, translocate to DSB foci by a mechanism requiring the activity of poly(ADP-ribose) polymerase-1 (PARP-1). At DNA repair foci, NR4A is phosphorylated by DNA-PK and promotes DSB repair. Notably, NR4A transcriptional activity is entirely dispensable in this function, and core components of the DNA repair machinery are not transcriptionally regulated by NR4A. Instead, NR4A functions directly at DNA repair sites by a process that requires phosphorylation by DNA-PK. Furthermore, a severe combined immunodeficiency (SCID)-causing mutation in the human gene encoding the DNA-PK catalytic subunit impairs the interaction and phosphorylation of NR4A at DSBs. Thus, NR4As represent an entirely novel component of DNA damage response and are substrates of DNA-PK in the process of DSB repair.

Abundant class of non-coding RNA regulates development in the social amoeba Dictyostelium discoideum

Non-coding (nc)RNAs are important players in most biological processes. Although small RNAs such as microRNAs and small interfering RNAs have emerged as exceptionally important regulators of gene expression, great numbers of larger ncRNAs have also been identified. Many of these are abundant and differentially expressed but their functions have in most cases not been elucidated. The social amoeba Dictyostelium discoideum contain the ncRNAs commonly found in eukaryotes. In addition, we previously reported the identification of two novel classes of 42-65 nt long stem-loop forming RNAs, Class I and Class II RNAs, with unknown function. In this study we have further characterized these abundant ncRNAs, which are down regulated during development. We have confirmed expression of 29 Class I RNAs and experimentally verified the formation of the computationally predicted short conserved stem structure. Furthermore, we have for the first time created knockout strains for several small ncRNA genes in D. discoideum and found that deletion of one of the Class I RNAs, DdR-21, results in aberrant development. In addition we have shown that this Class I RNA forms a complex with one or several proteins but do not appear to be associated with ribosomes or polysomes. In a pull down assay, several proteins interacting with DdR-21 were identified, one of these has two RNA recognition motifs (RRMs). The purified RRM containing protein was demonstrated to bind directly and specifically to DdR-21.

Immunodominant proteins α-1 giardin and β-giardin are expressed in both assemblages A and B of Giardia lamblia

Background

To date, eight assemblages of Giardia lamblia have been described, but only assemblages A and B are known to infect humans. Despite the fact that the genomic, biological, and clinical differences found between these two assemblages has raised the possibility that they may be considered different species, there is relatively limited information on their phenotypic differences. In the present study, we developed monoclonal antibodies against alpha-1 and beta giardin, two immunodominant proteins produced during G. lamblia infection, and studied their expression and localization in WB (assemblage A) and GS trophozoites (assemblage B).

Results

The polyclonal antibodies generated against WB trophozoites, particularly those recognizing intracellular proteins as well as the proteins present at the plasma membrane (variable-specific surface proteins), showed cross-reactivity with intracellular proteins in GS trophozoites. The use of monoclonal antibodies against beta giardin indicated ventral disc localization, particularly at the periphery in WB trophozoites. Interestingly, although beta giardin was also restricted to the ventral disc in GS trophozoites, the pattern of localization clearly differed in this assemblage. On the other hand, monoclonal antibodies against alpha-1 giardin showed plasma membrane localization in both assemblages with the bare area of GS trophozoites also being distinguished. Moreover, the same localization at the plasma membrane was observed in Portland-1 (Assemblage A) and in P15 (Assemblage E) trophozoites.

Conclusions

We found differences in localization of the beta giardin protein between assemblages A and B, but the same pattern of localization of alpha-1 giardin in strains from Assemblages A, B and E. These findings reinforce the need for more studies based on phenotypic characteristics in order to disclose how far one assemblage is from the other.

Bovine (Bos taurus) humoral immune response against Echinococcus granulosus and hydatid cyst infertility

Echinococcus granulosus, the agent of hydatid disease, presents an indirect life cycle, with canines (mainly dogs) as definitive hosts, and herbivores and human as intermediary ones. In intermediary hosts fertile and infertile cysts develop, but only the first ones develop protoscoleces, the parasite form infective to definitive hosts. We report the presence of bovine IgGs in the germinal layer from infertile cysts (GLIC), in an order of magnitude greater than in the germinal layer from fertile cysts (GLFC). When extracted with salt solutions, bovine IgGs from GLIC are associated with low or with high affinity (most likely corresponding to non specific and antigen specific antibodies, respectively). Specific IgGs penetrate both the cells of the germinal layer and HeLa cultured cells and recognize parasitic proteins. These results, taken together with previous ones from our laboratory, showing induction of apoptosis in the germinal layer of infertile hydatid cysts, provide the first coherent explanation of the infertility process. They also offer the possibility of identifying the parasite antigens recognized, as possible targets for immune modulation.

Positioning of a polymorphic quantitative trait nucleotide in the Ncf1 gene controlling oxidative burst response and arthritis severity in rats

The Ncf1 gene, encoding the P47(PHOX) protein that regulates production of reactive oxygen species (ROS) by the phagocyte NADPH oxidase (NOX2) complex, is associated with autoimmunity and arthritis severity in rats. We have now identified that the single-nucleotide polymorphism (SNP) resulting in an M153T amino acid substitution mediates arthritis resistance and thus explains the molecular polymorphism underlying the earlier identified Ncf1 gene effect. We identified the SNP in position 153 to regulate ROS production using COS(PHOX) cells transfected with mutated Ncf1. To determine the role of this SNP for control of arthritis, we used the Wistar strain, identified to carry only the postulated arthritis resistant SNP in position 153. When this Ncf1 allele was backcrossed to the arthritis susceptible DA strain, both granulocyte ROS production and arthritis resistance were restored. Position 153 is located in the hinge region between the PX and SH3 domains of P47(PHOX). Mutational analysis of this position revealed a need for an -OH group in the side chain but we found no evidence for phosphorylation. The polymorphism did not affect assembly of the P47(PHOX)/P67(PHOX) complex in the cytosol or membrane localization, but is likely to operate downstream of assembly, affecting activity of the membrane NOX2 complex.

Proteome profiling of immortalization-to-senescence transition of human breast epithelial cells identified MAP2K3 as a senescence-promoting protein which is downregulated in human breast cancer

PURPOSE

immortalization is one of the first changes in cells undergoing carcinogenic transformation. Proteome profiling of the immortalization-senescence transition is expected to provide insights into the molecular mechanisms of early tumorigenesis.

EXPERIMENTAL DESIGN

2-DE and MALDI-MS were used to identify proteins in primary human breast epithelial cells, relevant to the immortalization-senescence transition. Cell and molecular biology and immunohistochemistry were used to validate involvement of mitogen-activated protein kinase kinase 3 (MAP2K3) in the immortalization-senescence transition.

RESULTS

we identified 71 proteins whose expression changed upon induction of senescence. The identified proteins include regulators of cell growth, death, cell assembly and organization. Analysis of the network formed by the identified proteins suggested that the immortalization-to-senescence transition could affect regulators of the cell cycle, protein synthesis, transport, post-translational modifications, DNA recombination and repair, and lipid and amino acid metabolism. We observed that MAP2K3 was downregulated in immortal human breast epithelial cells and that upregulation of MAP2K3 expression promoted cell senescence. Decreased expression of MAP2K3 was observed in human breast infiltrating ductal carcinomas, as compared to non-cancerous human breast tissues.

CONCLUSION AND CLINICAL RELEVANCE

we described a proteome profile of the immortalization-to-senescence transition for human breast epithelial cells, and identified MAP2K3 as a protein that promotes senescence in these cells.

Cys-X scanning for expansion of active-site residues and modulation of catalytic functions in a glutathione transferase

We propose Cys-X scanning as a semisynthetic approach to engineer the functional properties of recombinant proteins. As in the case of Ala scanning, key residues in the primary structure are identified, and one of them is replaced by Cys via site-directed mutagenesis. The thiol of the residue introduced is subsequently modified by alternative chemical reagents to yield diverse Cys-X mutants of the protein. This chemical approach is orthogonal to Ala or Cys scanning and allows the expansion of the repertoire of amino acid side chains far beyond those present in natural proteins. In its present application, we have introduced Cys-X residues in human glutathione transferase (GST) M2-2, replacing Met-212 in the substrate-binding site. To achieve selectivity of the modifications, the Cys residues in the wild-type enzyme were replaced by Ala. A suite of simple substitutions resulted in a set of homologous Met derivatives ranging from normethionine to S-heptyl-cysteine. The chemical modifications were validated by HPLC and mass spectrometry. The derivatized mutant enzymes were assayed with alternative GST substrates representing diverse chemical reactions: aromatic substitution, epoxide opening, transnitrosylation, and addition to an ortho-quinone. The Cys substitutions had different effects on the alternative substrates and differentially enhanced or suppressed catalytic activities depending on both the Cys-X substitution and the substrate assayed. As a consequence, the enzyme specificity profile could be changed among the alternative substrates. The procedure lends itself to large-scale production of Cys-X modified protein variants.

HDAC2 and TXNL1 distinguish aneuploid from diploid colorectal cancers

DNA aneuploidy has been identified as a prognostic factor for epithelial malignancies. Further understanding of the translation of DNA aneuploidy into protein expression will help to define novel biomarkers to improve therapies and prognosis. DNA ploidy was assessed by image cytometry. Comparison of gel-electrophoresis-based protein expression patterns of three diploid and four aneuploid colorectal cancer cell lines detected 64 ploidy-associated proteins. Proteins were identified by mass spectrometry and subjected to Ingenuity Pathway Analysis resulting in two overlapping high-ranked networks maintaining Cellular Assembly and Organization, Cell Cycle, and Cellular Growth and Proliferation. CAPZA1, TXNL1, and HDAC2 were significantly validated by Western blotting in cell lines and the latter two showed expression differences also in clinical samples using a tissue microarray of normal mucosa (n=19), diploid (n=31), and aneuploid (n=47) carcinomas. The results suggest that distinct protein expression patterns, affecting TXNL1 and HDAC2, distinguish aneuploid with poor prognosis from diploid colorectal cancers.

Elongation factor 1-alpha is released into the culture medium during growth of Giardia intestinalis trophozoites

The molecular pathogenesis of the intestinal parasite Giardia intestinalis is still not fully understood but excretory-secretory products have been suggested to be important during host-parasite interactions. Here we used SDS-PAGE gels and MALDI-TOF analysis to identify proteins released by Giardia trophozoites during in vitro growth. Serum proteins (mainly bovine serum albumin) in the growth medium, bind to the parasite surface and they are continuously released, which interfere with parasite secretome characterization. However, we identified two released Giardia proteins: elongation factor-1 alpha (EF-1α) and a 58 kDa protein, identified as arginine deiminase (ADI). This is the first description of EF-1α as a released/secreted Giardia protein, whereas ADI has been identified in an earlier secretome study. Two genes encoding EF-1α were detected in the Giardia WB genome 35 kbp apart with almost identical coding sequences but with different promoter and 3' regions. Promoter luciferase-fusions showed that both genes are transcribed in trophozoites. The EF-1α protein localizes to the nuclear region in trophozoites but it relocalizes to the cytoplasm during host-cell interaction. Recombinant EF-1α is recognized by serum from giardiasis patients. Our results suggest that released EF-1α protein can be important during Giardia infections.

Meta-data analysis as a strategy to evaluate individual and common features of proteomic changes in breast cancer

BACKGROUND

Individual differences among breast tumours in patients is a significant challenge for the treatment of breast cancer. This study reports a strategy to assess these individual differences and the common regulatory mechanisms that may underlie breast tumourigenesis.

MATERIALS AND METHODS

The two-step strategy was based firstly on a full-scale proteomics analysis of individual cases, and secondly on the analysis of common features of the individual proteome-centred networks (meta-data).

RESULTS

Proteomic profiling of human invasive ductal carcinoma tumours was performed and each case was analysed individually. Analysis of primary datasets for common cancer-related proteins identified keratins. Analysis of individual networks built with identified proteins predicted features and regulatory mechanisms involved in each individual case. Validation of these findings by immunohistochemistry confirmed the predicted deregulation of expression of CK2α, PDGFRα, PYK and p53 proteins.

CONCLUSION

Meta-data analysis allowed efficient evaluation of both individual and common features of the breast cancer proteome.

PARP-1 attenuates Smad-mediated transcription

The versatile cytokine transforming growth factor β (TGF-β) regulates cellular growth, differentiation, and migration during embryonic development and adult tissue homeostasis. Activation of TGF-β receptors leads to phosphorylation of Smad2 and Smad3, which oligomerize with Smad4 and accumulate in the nucleus where they recognize gene regulatory regions and orchestrate transcription. Termination of Smad-activated transcription involves Smad dephosphorylation, nuclear export, or ubiquitin-mediated degradation. In an unbiased proteomic screen, we identified poly(ADP-ribose) polymerase-1 (PARP-1) as a Smad-interacting partner. PARP-1 dissociates Smad complexes from DNA by ADP-ribosylating Smad3 and Smad4, which attenuates Smad-specific gene responses and TGF-β-induced epithelial-mesenchymal transition. Thus, our results identify ADP-ribosylation of Smad proteins by PARP-1 as a key step in controlling the strength and duration of Smad-mediated transcription.

Differential expression of ANXA6, HSP27, PRDX2, NCF2, and TPM4 during uterine cervix carcinogenesis: diagnostic and prognostic value

Background:

Cytology-based diagnostics of squamous cervical cancer (SCC) precursor lesions is subjective and can be improved by objective markers.

Methods:

IHC-based analysis of ANXA6, HSP27, peroxiredoxin 2 (PRDX2), NCF2, and tropomyosin 4 (TPM4) during SCC carcinogenesis.

Results:

Expression of ANXA6, HSP27, PRDX2, and NCF2 in the cytoplasm of dysplastic cells increased from cervical intraepithelial neoplasia 2/3 (CIN2/3) to microinvasive cancer. Invasive SCC showed lower expression of TPM4 than CIN and normal epithelium. CIN2/3 with the highest sensitivity and specificity differed from normal epithelium by cytoplasmic expression of HSP27. Patients with cytoplasmic HSP27 expression in SCC deviating from that observed in normal epithelium had worse relapse-free (P=0.019) and overall (P=0.014) survival. Invasive SCC with the highest sensitivity and specificity differed from normal epithelium by expression of PRDX2 and TPM4 in the cytoplasm, from CIN2/3 by the expression of ANXA6 and TPM4 in the cytoplasm, and from microinvasive SCC by the expression of PRDX2 and ANXA6 in the cytoplasm. The number of sporadic ANXA6+ cells between the atypical cells increased from CIN2/3 to invasive SCC.

Conclusion:

Detection of expression changes of the proteins ANXA6, HSP27, PRDX2, NCF2, and TPM4 in SCC precursor lesions may aid current cytological and pathological diagnostics and evaluation of prognosis.

Variation in amount of wild-type transthyretin in different fibril and tissue types in ATTR amyloidosis

Familial transthyretin (TTR) amyloidosis is caused by a mutation in the TTR gene, although wild-type (wt) TTR is also incorporated into the amyloid fibrils. Liver transplantation (LT) is the prevailing treatment of the disease and is performed in order to eliminate the mutant TTR from plasma. The outcome of the procedure is varied; especially problematic is a progressive cardiomyopathy seen in some patients, presumably caused by continued incorporation of wtTTR. What determines the discrepancy in outcome is not clear. We have previously shown that two structurally distinct amyloid fibrils (with or without fragmented ATTR) are found among ATTRV30M patients. In this study, we investigated the proportion of wtATTR in cardiac and adipose amyloid from patients having either fibril type. It was found that cardiac amyloid more easily incorporates wtTTR than adipose amyloid, offering a potential explanation for the vulnerability of cardiac tissue for continued amyloidosis after LT. In cardiac tissue, fibrils with fragmented ATTR contained a higher wt proportion than fibrils without, suggesting that continued incorporation of wtTTR after LT, perhaps, can take place more easily in these patients. In adipose tissue, a rapid increase in wt proportion after LT indicates that a rather fast turnover of the deposits must occur. A difference in wt proportion between the fibril types was seen post-LT but not pre-LT, possibly caused by differences in turnover rate. Conclusively, this study further establishes the basic dissimilarities between the two fibril types and demonstrates that their role in LT outcome needs to be further investigated.

Epstein-Barr virus encoded EBNA-3 binds to vitamin D receptor and blocks activation of its target genes

Epstein-Barr virus (EBV) is a human gamma herpes virus that infects B cells and induces their transformation into immortalized lymphoblasts that can grow as cell lines (LCLs) in vitro. EBNA-3 is a member of the EBNA-3-protein family that can regulate transcription of cellular and viral genes. The identification of EBNA-3 cellular partners and a study of its influence on cellular pathways are important for understanding the transforming action of the virus. In this work, we have identified the vitamin D receptor (VDR) protein as a binding partner of EBNA-3. We found that EBNA3 blocks the activation of VDR-dependent genes and protects LCLs against vitamin-D3-induced growth arrest and/or apoptosis. The presented data shed some light on the anti-apoptotic EBV program and the role of the EBNA-3-VDR interaction in the viral strategy.

The activity of hyaluronan synthase 2 is regulated by dimerization and ubiquitination

Hyaluronan is a component of the extracellular matrix, which affects tissue homeostasis. In this study, we investigated the regulatory mechanisms of one of the hyaluronan-synthesizing enzymes, HAS2. Ectopic expression of Flag- and 6myc-HAS2 in COS-1 cells followed by immunoprecipitation and immunoblotting revealed homodimers; after co-transfection with Flag-HAS3, also heterodimers were seen. Furthermore, the expressed HAS2 was ubiquitinated. We identified one acceptor site for ubiquitin on lysine residue 190. Mutation of this residue led to inactivation of the enzymatic activity of HAS2. Interestingly, K190R-mutated HAS2 formed dimers with wt HAS2 and quenched the activity of wt HAS2, thus demonstrating a functional role of the dimeric configuration.

Barley as a green factory for the production of functional Flt3 ligand

Biologically active recombinant human Flt3 ligand was expressed and isolated from transgenic barley seeds. Its expression is controlled by a tissue specific promoter that confines accumulation of the recombinant protein to the endosperm tissue of the seed. The recombinant Flt3 ligand variant expressed in the seeds contains an HQ-tag for affinity purification on immobilized metal ion affinity chromatography (IMAC) resin. The tagged protein was purified from seed extracts to near homogeneity using sequential chromatography on IMAC affinity resin and cation exchange resin. We also show that the recombinant Flt3 ligand protein undergoes posttranslational modifications: it is a glycoprotein containing alpha-1,3-fucose and alpha-1,2-xylose. The HQ-tagged Flt3 ligand variant exhibits comparable biological activity to commercial Flt3 ligand. This is the first report showing expression and accumulation of recombinant human growth factor in barley seeds with a yield of active protein similar to a bacterial expression system. The present results demonstrate that plant molecular farming is a viable approach for the bioproduction of human-derived growth factors.

Identification of glycoproteins targeted by Trypanosoma cruzi trans-sialidase, a virulence factor that disturbs lymphocyte glycosylation

Trypanosoma cruzi, the agent of the American trypanosomiasis or Chagas disease, bypasses its lack of de novo synthesis of sialic acids by expressing a surface-anchored trans-sialidase. This enzyme transfers sialic acid residues from the host's sialylglycoconjugates to the parasite's galactosylglycoconjugates. In addition to carrying out a pivotal role in parasite persistence/replication within the infected mammal, the trans-sialidase is shed into the bloodstream and induces alterations in the host immune system by modifying the sialylation of the immune cells. A major obstacle to understand these events is the difficulty to identify the transferred sialic acid among all those naturally occurring on the cell surface. Here, we report the use of azido-modified unnatural sialic acid to identify those molecules that act as cell surface acceptors of the sialyl residue in the trans-sialidase-catalyzed reaction, which might then be involved in the immune alterations induced. In living parasites, we readily observed the transfer of azido-sialic acid to surface mucins. When evaluating mouse thymocytes and splenocytes as acceptors of the azido-sugar, a complex pattern of efficiently tagged glycoproteins was revealed. In both leukocyte populations, the main proteins labeled were identified as different CD45 isoforms. Disruption of the cell architecture increased the number and the molecular weight distribution of azido-sialic acid tagged proteins. Nevertheless, CD45 remained to be the main acceptor. Mass spectrometry assays allowed us to identify other acceptors, mainly integrins. The findings reported here provide a molecular basis to understand the abnormalities induced in the immune system by the trans-sialidase during T. cruzi infection.

Phosphorylation of thymidylate synthase from various sources by human protein kinase CK2 and its catalytic subunits

Thymidylate synthase (TS) was found to be a substrate for both catalytic subunits of human CK2, with phosphorylation by CK2alpha and CK2alpha' characterized by similar K(m) values, 4.6microM and 4.2microM, respectively, but different efficiencies, the apparent turnover number with CK2alpha being 10-fold higher. With both catalytic subunits, phosphorylation of human TS, like calmodulin and BID, was strongly inhibited in the presence of the regulatory subunit CK2beta, the holoenzyme being activated by polylysine. Phosphorylation of recombinant human, rat, mouse and Trichinella spiralis TSs proteins was compared, with the human enzyme being apparently a much better substrate than the others. Following hydrolysis and TLC, phosphoserine was detected in human and rat, and phosphotyrosine in T. spiralis, TS, used as substrates for CK2alpha. MALDI-TOF MS analysis led to identification of phosphorylated Ser(124) in human TS, within a sequence LGFS(124)TREEGD, atypical for a CK2 substrate recognition site. The phosphorylation site is located in a region considered important for the catalytic mechanism or regulation of human TS, corresponding to the loop 107-128. Following phosphorylation by CK2alpha, resulting in incorporation of 0.4mol of phosphate per mol of dimeric TS, human TS exhibits unaltered K(m) values for dUMP and N(5,10)-methylenetetrahydrofolate, but a 50% lower turnover number, pointing to a strong influence of Ser(124) phosphorylation on its catalytic efficiency.

A new highly toxic protein isolated from the death cap Amanita phalloides is an L-amino acid oxidase

A new highly cytotoxic protein, toxophallin, was recently isolated from the fruit body of the death cap Amanita phalloides mushroom [Stasyk et al. (2008) Studia Biologica 2, 21-32]. The physico-chemical, chemical and biological characteristics of toxophallin differ distinctly from those of another death cap toxic protein, namely phallolysin. The interaction of toxophallin with target cells is not mediated by a specific cell surface receptor. It induces chromatin condensation, as well as DNA and nucleus fragmentation, which are typical for apoptosis. However, caspase III inhibitor [benzyloxycarbonyl-Asp(OMe)-fluoromethylketone] did not stop toxophallin-induced DNA fragmentation. Thus, toxophallin uses a caspase-independent pathway of apoptosis induction. In the present study, we applied a complementary approach based on a combination of proteomics and molecular biology tools for the protein identification of toxophallin. The primary structure of toxophallin was partially studied via direct sequencing of its tryptic peptides, followed by PCR-based cloning of the corresponding cDNA. A subsequent bioinformatic search revealed a structural homology of toxophallin with the l-amino acid oxidase of the Laccaria bicolor mushroom. This demonstrates the usefulness of our approach for the identification of proteins in organisms with unknown genomes. We also found a broad substrate specificity of toxophallin with respect to oxidizing selected amino acids. Ascorbic acid inhibited the cytotoxic effect of toxophallin, most likely as a result of scavenging hydrogen peroxide, which is the product of oxidase catalysis. Thus, in addition to highly toxic cyclopeptides and toxic lectin phallolysin, the death cap fruit body contains another cytotoxic protein in the form of an enzyme, namely l-amino acid oxidase.

Diagnostic protein marker patterns in squamous cervical cancer

PURPOSE

Cervical cancer is the second most prevalent malignancy of women. Our aim was to identify additional marker protein patterns for objective diagnosis of squamous cervical cancer (SCC).

EXPERIMENTAL DESIGN

Collected tissue biopsies of SCC, squamous vaginal cancer (SVC), normal cervical and vaginal mucosa were subjected to 2-DE, SameSpot analysis, MALDI-TOF-MS protein identification, and analysis of the expression of selected proteins by immunohistochemistry.

RESULTS

In 148 protein spots selected by the difference in expression 99 proteins were identified. A differential protein pattern for SCC was, e.g. over-expressed (OE) eukaryotic translation initiation factor 3-2β, neutrophil cytosolic factor 2, annexin A6 (ANXA6), for SVC it was OE cathepsin D, γ-catenin, RAB2A, for both cancers it was OE apolipoprotein E, tropomyosin 3, HSPA8, and underexpressed cytokeratin 13, osteoglycin. In SCC nuclear expression of neutrophil cytosolic factor 2, PRDX2, HSP27 (nine of ten cases), ANXA6 (nine of ten cases) was observed while tropomyosin 4 was expressed only in two of ten cases. There was 81.1% (43/53) agreement between the expression of protein spots and the immune expression of proteins (www.proteinatlas.org).

CONCLUSIONS AND CLINICAL RELEVANCE

SCC is characterized by specific tissue marker protein patterns that allow objective detection of the disease. They can become a basis for objective automated cytology-based screening and improve current diagnostics of SCC.

The apoptosis modulating role of SAP (SLAM associated protein) contributes to the symptomatology of the X linked lymphoproliferative disease

Deletion or mutation of the SH2D1A gene located at Xq25 is responsible for the development of the X-linked lymphoproliferative disease, XLP. Primary infection of the affected individuals with EBV leads to fulminant and often fatal infectious mononucleosis, FIM. Moreover, they run a 200 fold elevated risk for lymphoma development. Due to the critical role of the immune response for the outcome of EBV infection and the detection of EBV genomes in several malignancies, XLP studies have been mainly focused on the immunological aspects. The involvement of SAP in the apoptotic machinery provides a further aspect in the complex syndrome of XLP. Functional impairment of SAP leads to defective apoptotic responses. Activation induced apoptosis plays a pivotal role in the termination of the lymphocyte proliferation in IM. This mechanism is inefficient in XLP patients. In addition, in the absence of SAP, lymphoma development may be promoted by the illegitimate survival of lymphocytes with damaged DNA that would be normally eliminated by apoptosis.

Proteomic analysis of protein expression in human tonsillar cancer: differentially expressed proteins characterize human tonsillar cancer

BACKGROUND

Head and neck cancer continues to be one of the most common tumor entities worldwide. Within this group of malignancies, tonsillar squamous cell carcinoma represent approximately 15-20% of all intraoral and oropharyngeal carcinomas in the United States. Accurate and early stage diagnosis still remains a major challenge, as patients are often presented at an advanced stage of disease, causing a low overall survival rate. Thus, new diagnostic markers are highly desirable and could allow for a more reliable diagnosis, with further insights into carcinogenesis and tumor biology. Furthermore, these markers could be the basis for new therapeutic targets and early disease detection. To address these issues, we decided to use a global proteomic approach to characterize tonsillar squamous cell carcinoma.

MATERIALS AND METHODS

A total of 19 tonsillar carcinoma samples and 12 benign controls acquired from the corresponding normal epithelium were analyzed by 2-D gel electrophoresis. 2-DE gels were silver stained and analyzed using the PDQuest analysis software (BioRad). Tumor specific spots were detected and identified by consecutive MALDI-TOF-MS or MS/MS polypeptide identification.

RESULTS

In total, 70 proteins showed significant quantitative differences in protein expression, with 50 polypeptides accessible for identification. Of those 50 polypeptides, we were able to identify a total of 27 proteins and protein isoforms, significantly up- or down-regulated in tonsillar cancer samples. In addition to previously reported polypeptides in head and neck cancers, we were able to identify several new potential marker proteins in this study.

CONCLUSION

Our results show that a combination of tonsillar cancer specific proteins can be used for histopathological diagnosis and may serve as a basis for discovering further biomarkers for early detection and prediction of response to treatment in the future.

Galectin-8 provides costimulatory and proliferative signals to T lymphocytes

Galectin (Gal) constitute a family of carbohydrate-recognizing molecules ubiquitously expressed in mammals. In the immune system, they regulate many processes such as inflammation, adhesion, and apoptosis. Here, we report the expression in the spleen of the two same Gal-8 splice variants described previously in the thymus. Gal-8 was found to induce two separate biological activities on T lymphocytes: a robust naive CD4(+) T cell proliferation in the absence of antigen and notably, a costimulatory signal that synergized the cognate OVA peptide in DO11.10 mice transgenic for TCR(OVA). The antigen-independent proliferation induced by Gal-8 displayed increased expression of pro- and anti-inflammatory cytokines, thus suggesting the polyclonal expansion of Th1 and Th2 clones. The costimulatory effect on antigen-specific T cell activation was evidenced when the Gal and the peptide were assayed at doses suboptimal to induce T cell proliferation. By mass spectra analysis, several integrins and leukocyte surface markers, including CD45 isoforms, as well as other molecules specific to macrophages, neutrophils, and platelets, were identified as putative Gal-8 counter-receptors. Gal-8 triggered pZAP70 and pERK1/2. Moreover, pretreatment with specific inhibitors of CD45 phosphatase or ERK1/2 prevented its antigen-dependent and -independent T cell-proliferative activities. This seems to be associated with the agonistic binding to CD45, which lowers the activation threshold of the TCR signaling pathway. Taken together, our findings support a distinctive role for locally produced Gal-8 as an enhancer of otherwise borderline immune responses and also suggest that Gal-8 might fuel the reactivity at inflammatory foci.