Publisher Correction: SLX4 interacts with RTEL1 to prevent transcription-mediated DNA replication perturbations

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

P3666Spondylitis: a frequent and severe complication of infective endocarditis

Background

Spondylodiscitis (SP) is a rare, but severe complication of infective endocarditis (IE). The incidence, clinical features and prognosis of SP in IE are unknown.

Purpose

The primary objective of our study was to assess the incidence, epidemiology, clinical presentation, prognosis, and therapeutic implications of SP in patient with IE. The secondary objectives were to assess factors associated with occurrence of spondylitis and to assess the value of imaging techniques.

Methods

In a French bi-center prospective study of patients who presented in our endocarditis reference centers with a diagnosis of definite IE from 1990 to 2018 (n=1755), 150 (8.5%) presented with SP. Clinical, epidemiological, microbiological, and prognostic variables were prospectively recorded and compared between patients with (n=150) and without (n=1605) SP.

Results

Patients with SP were older (mean age 69.7±18 vs 66.2±14; p=0.004), had more arterial hypertension (48% vs 34,5%; p<0.001) and autoimmune disease (5% vs 2%; p=0.03) than patients without SP. The lumbar vertebrae were the most frequently involved (84 patients, 66%), especially L3-L4. Neurological symptoms were observed in 59% of patients. Enterococci et Gallolyticus streptococci were more frequent (24% vs 12% and 24% vs 11%; p<0,001, respectively) in the SP group. Observed sensitivities of full spine contrast-enhanced MRI and CT were 95% and 89%, respectively. PET/CT had a great power to differentiate infective to degenerative vertebral processes, and to find embolic foci with a sensitivity of 90%. Clinical outcome did not differ between patients with or without SP, including similar in-hospital mortality (16% vs 13,5%, p=0.38).

Conclusions

We describe the largest ever reported series of patients with spondylodiscitis complicating IE. Spondylodiscitis is a more frequent complication of IE than previously reported (8.5% of IE), is observed in older hypertensive patients with Enterococcal or Streptococcus gallolyticus IE and has a similar prognosis than other forms of IE. Since SP is associated with prolonged antibiotic therapy and may need specific surgical therapy, multimodality imaging including MRI, CT, and PET/CT should be used for early diagnosis of this IE complication.

333018F-Fluorodeoxyglucose Positron Emission Tomography Computed Tomography (PET/CT) for the diagnosis of prosthetic valve infective endocarditis (PVIE): a prospective multicenter study

Background and objectives

18F-FDG PET/CT has recently been added as a major criterion in the ESC 2015 infective endocarditis (IE) guidelines, but the value of this new diagnostic algorithm has never been prospectively assessed.

Purposes

1. Primary objective: to assess the value of the new ESC criteria including 18F-FDG PET/CT in prosthetic valve infective endocarditis (PVIE).

2. Secondary objectives: to determine the reproducibility of 18F-FDG PET/CT; to assess its ability to predict embolic events.

Methods

Between 2014 and 2017, 175 patients with suspected PVIE were prospectively included in 3 French centers. After exclusion of patients with uninterpretable or not feasible PET/CT,115 patients were finally included in the analysis, including 91 definite IE and 24 rejected IE, as defined by an expert Consensus of Endocarditis Team after 3-month follow-up as Gold Standard

Nuclear data were blindly analyzed by two independent nuclear medicine physicians.

Patients follow-up was scheduled at one and three months after hospitalization

Results

Significant cardiac uptake by PET/CT (major criterion) was observed in 67 among 91 patients with definite PVIE and 6 patients with rejected IE (sensitivity 73.6%, specificity 75%, positive predictive value 91%, negative predictive value 42%). Considering cardiac uptake as a major criterion, the ESC 2015 classification increased the sensitivity of Duke criteria from 57 to 84% (p<0.001) but decreased its specificity from 84 to 70% (p<0.001).

Intraobserver reproducibility of cardiac uptake evaluation was good (kappa = 0.84) but inter observer reproductibility was less satisfactory (kappa = 0.63).

Embolic events occurred in 31 patients (27%) and were correlated with vegetation size by ECHO (p<0.001), Staphylococcus infection (p=0.003), and PET/CT cardiac uptake (p=0.02).

Conclusion

1. the value of PET CT and ESC criteria is confirmed and may allow earlier diagnosis of PVIE

2. PET CT is associated with an increased risk of false positive results probably related to the technical improvements

3. Reproducibility of nuclear measurements seems unsatisfactory, justifying efforts to standardize PET studies interpretation

4. Our study describes for the first time a positive correlation between a positive PET/Ct and occurrence of embolic events, warranting additional studies.

Early prognostic factors in septic shock cancer patients: a prospective study with a proteomic approach

BACKGROUND

Organ failures are the main prognostic factors in septic shock. The aim was to assess classical clinico-biological parameters evaluating organ dysfunctions at intensive care unit admission, combined with proteomics, on day-30 mortality in critically ill onco-hematology patients admitted to the intensive care unit for septic shock.

METHODS

This was a prospective monocenter cohort study. Clinico-biological parameters were collected at admission. Plasma proteomics analyses were performed, including protein profiling using isobaric Tag for Relative and Absolute Quantification (iTRAQ) and subsequent validation by ELISA.

RESULTS

Sixty consecutive patients were included. Day-30 mortality was 47%. All required vasopressors, 32% mechanical ventilation, 33% non-invasive ventilation and 13% renal-replacement therapy. iTRAQ-based proteomics identified von Willebrand factor as a protein of interest. Multivariate analysis identified four factors independently associated with day-30 mortality: positive fluid balance in the first 24 h (odds ratio = 1.06, 95% CI = 1.01-1.12, P = 0.02), severe acute respiratory failure (odds ratio = 6.14_, 95% CI = 1.04-36.15, P = 0.04), von Willebrand factor plasma level > 439 ng/ml (odds ratio = 9.7, 95% CI = 1.52-61.98, P = 0.02), and bacteremia (odds ratio = 6.98, 95% CI = 1.17-41.6, P = 0.03).

CONCLUSION

Endothelial dysfunction, revealed by proteomics, appears as an independent prognostic factor on day-30 mortality, as well as hydric balance, acute respiratory failure and bacteremia, in critically ill cancer patients admitted to the intensive care unit. Endothelial failure is underestimated in clinical practice and represents an innovative therapeutic target.

Evidence for the Expression of Urokinase-type Plasminogen Activator by Human Venous Endothelial Cells In Vivo

Endothelial cells (ECs) in culture synthesize and secrete urokinase-type plasminogen activator (u-PA), but the normal vascular endothelium is believed to synthesize only tissue plasminogen activator (t-PA), which is thought to be responsible for intravascular fibrinolysis. More recently, animal studies have shown that the biological role of u-PA in fibrinolysis has been underestimated, prompting a re-examination of its synthesis by the endothelium. In this study, we investigated whether u-PA was synthesized by non-atherosclerotic endothelial cells in vivo by testing ECs dislodged by venipuncture from 12 normal volunteers and 17 patients admitted for plasmapheresis. The ECs were isolated with an anti-endothelial monoclonal antibody coupled to immunomagnetic beads and characterized by morphology and by labelling for vWF, CD31, and UEA-1 binding. U-PA antigen was found in 50% of the ECs from the normal subjects and in 60% of those from patients. U-PA enzymatic activity on zymograms was detected in 50% of the normal samples and 60% of the patient samples, with the latter being more frequently and more strongly positive. U-PA mRNA was found in all the normal and patient samples tested. The results indicate that u-PA is synthesized by the venous endothelium in vivo but that its expression is highly variable.

Abstract P6-12-08: Serum biomarkers identification using quantitative proteomics in patients with HER2-positive inflammatory breast cancer receiving trastuzumab plus bevacizumab-based chemotherapy (BEVERLY 2 trial)

Background

Inflammatory breast cancer (IBC) is a rare but aggressive form of locally advanced breast cancer, the optimal systemic treatment of which is still discussed. Beverly 2 trial was a phase II study evaluating the efficacy and safety of a preoperative regimen associating bevacizumab, trastuzumab, and chemotherapy in 52 patients with non-metastatic HER2-positive IBC, reporting a promising rate of pathological complete response (pCR, 63.5%, 95% CI 49.4–77.5; Pierga et al, Lancet Oncol, 2012). During the study, serum samples were collected at baseline and subjected to proteomic-based approaches to identify circulating biomarkers predictive of treatment response.

Methods

Baseline serum samples from responsive (pCR, according to Sataloff classification, n = 12) and non-responsive (no pCR, n = 11) patients were subjected to isobaric Tag for Relative and Absolute Quantification (iTRAQ)-based proteomics. Samples were pooled according to pCR and hormone receptor (HR) status, to constitute 4 independent mixes (pCR/HR-positive, pCR/HR-negative, nopCR/HR-positive, nopCR/HR-negative). Each of them underwent immuno-depletion of highly abundant proteins, concentration, reduction, alkylation and tryptic digestion. Then, each mix was fractionated and subjected to iTRAQ identification and quantitation using nano-liquid chromatography (LC) and electrospray ionisation (ESI)-orbitrap tandem mass spectrometry (MS/MS) (LTQ-orbitrap, Thermofisher). Differentially expressed proteins were analysed using IPA (IngenuitySystems) to highlight biological functions and signalling pathways that were most significantly enriched.

Results

iTRAQ-based measurements identified and quantified a total of 302 serum proteins. Among them, 48 proteins displayed a significant (fold-change &gt; 1.5 and p-value &lt; 0.05) differential expression between pCR and noPCR pts (18 proteins down-regultated and 30 proteins up-regulated in pCR patients), some of them previously described to be involved in breast cancer biology and/or angiogenesis, including : Alpha-1-acid glycoprotein 1, von Willebrand factor, Galectin-3-binding protein, serum amyloid A-1, Apolipoprotein E, Pigment epithelium-derived factor, Corticosteroid-binding globulin (down-regulated proteins in pCR patients); serum amyloid P-component, angiotensinogen, plasma serine protease inhibitor, carbonic anhydrase 1, mannose-binding protein C, hyaluronan-binding protein 2, peroxiredoxin-2, properdin, ADAMTS13, tetranectin, biotinidase, lumican (up-regulated proteins in pCR patients). Proteins with differential expression during treatment were involved in various biological processes, including cell-to-cell signaling and interaction, lipid metabolism, small molecule biochemistry, molecular transport, cellular function and maintenance as well as various canonical pathways such as acute phase response signalling, LXR/RXR activation and coagulation system.

Conclusion

iTRAQ-based quantitative proteomics identify serum proteins that could predict the therapeutic response to pre-operative trastuzumab plus bevacizumab-based chemotherapy in HER2-positive IBC.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-12-08.

Abstract P3-12-01: Serum biomarkers identification using quantitative proteomics in patients (pts) with untreated brain metastases from HER2-positive breast cancer receiving capecitabine (C) and lapatinib (L) (UNICANCER LANDsCAPE trial)

Background: The LANDsCAPE phase II study showed that C+L had a significant antitumor activity in previously untreated brain metastases (BM) from HER2-positive breast cancer (BC), with a central nervous system-objective response rate (CNS-ORR) of 67% and a median time to whole-brain radiotherapy (WBRT) of 8.3 months (43 analysed pts). Thus initial C+L combination might be a viable alternative to immediate WBRT in this setting. In this study, serum samples were collected before and during treatment for proteomic-based approaches to identify predictive biomarkers of treatment response.

Methods: Baseline (BL) and day 21 (D21) serum samples from highly responsive (R, CNS lesions -volumetric response ≥ 75%, n=6) and non-responsive (NR, CNS-stable or progressive disease, n=6) pts were subjected to isobaric Tag for Relative and Absolute Quantification (iTRAQ)-based proteomics. Samples from each condition were pooled to constitute 4 independent mixes ((BL-R, D21-R, BL-NR and D21-NR). Each of them underwent immuno-depletion of highly abundant proteins, concentration, reduction, alkylation and tryptic digestion. Then, each mix was fractionated and subjected to iTRAQ identification and quantitation using nano-liquid chromatography (LC) and electrospray ionisation (ESI)-orbitrap tandem mass spectrometry (MS/MS) (LTQ-orbitrap, Thermofisher). Differentially expressed proteins were analysed using IPA (Ingenuity® Systems) to highlight biological functions and signalling pathways that were most significantly enriched.

Results: iTRAQ-based measurements identified serum proteins with significant (fold-change &gt; 1.5 and p-value &lt; 0.05) differential expression between BL and D21, in R- (n = 38 proteins) and NR- pts (n = 18 proteins). At baseline, 30 proteins were differentially expressed between R-and NR-pts. Among the most differentially expressed proteins, some had been previously described as involved in cancer metastases (between BL and D21: tenascin C, neuropilin-1, Serpin A1, Cathepsin S, prostaglandin D2 synthase, melanoma cell adhesion molecules, procollagen C-endopeptidase enhancer; between R and NR: carnosine dipeptidase 1, endothelial protein C receptor, matrix metallopeptidase 9, cystatin C, lumican, plexin B2, Insulin-like growth factor binding protein acid labile subunit, pro-platelet basic protein, cadherin 5, Protein S). Proteins with differential expression during treatment were involved in various biological processes, including lipid metabolism, small molecule biochemistry, molecular transport, gene expression, cellular growth and proliferation, cellular movement and cancer, as well as various canonical pathways such as acute phase response signalling, LXR/RXR activation and complement system. Interestingly, and as opposed to NR-pts, R-pts specifically showed an overall increase in proteins of acute phase response, with a significant decrease in C-reactive protein (CRP).

Conclusion: iTRAQ-based quantitative proteomics identify serum proteins that could predict the therapeutic response to C+L combination in untreated BM from HER2-positive BC. If validated, such biomarkers may help to select the best therapeutic strategy in this setting.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-12-01.

Antifibroblast antibodies from systemic sclerosis patients bind to α-enolase and are associated with interstitial lung disease

Objective:

To identify target antigens of antifibroblast antibodies (AFA) in systemic sclerosis (SSc) patients.

Patients and Methods:

In the first part, sera from 24 SSc patients (12 with pulmonary arterial hypertension (PAH) and 12 without) and 36 idiopathic PAH patients, tested in pooled sera for groups of three, were compared with a sera pool from 14 healthy controls (HC). Serum IgG reactivity was analysed by the use of a two-dimensional electrophoresis and immunoblotting technique with normal human fibroblasts antigens. In the second part, serum IgG reactivity for two groups: 158 SSc, 67 idiopathic PAH and 100 HC; and 35 SSc and 50 HC was tested against α-enolase from Saccharomyces cerevisiae and recombinant human (rHu) α-enolase, respectively, on ELISA.

Results:

In the first part, α-enolase was identified as a main target antigen of AFA from SSc patients. In the second part, 37/158 (23%) SSc patients, 6/67 (9%) idiopathic PAH patients and 4/100 (4%) HC (p<0.001) had anti-S cerevisiae α-enolase antibodies; 12/35 (34%) SSc patients and 3/50 (6%) HC had anti-rHu α-enolase antibodies (p = 0.001). In SSc, the presence of anti-S cerevisiae α-enolase antibodies was associated with interstitial lung disease (ILD), decreased total lung capacity (73.2% vs 89.7%; p<0.001) and diffusion capacity for carbon monoxide (47.4% vs 62.3%; p<0.001), and antitopoisomerase 1 antibodies (46% vs 21%; p = 0.005) but not anticentromere antibodies (11% vs 34%; p = 0.006). Results were similar with rHu α-enolase testing.

Conclusion:

In SSc, AFA recognise α-enolase and are associated with ILD and antitopoisomerase antibodies.

The effect of stromelysin-1 (MMP-3) on non-collagenous extracellular matrix proteins of demineralized dentin and the adhesive properties of restorative resins

Dentin non-collagenous matrix components (NCPs) are structural proteins involved in the formation, the architecture and the mineralization of the extracellular matrix (ECM). We investigated here how recombinant metalloproteinase stromelysin-1, also termed MMP-3, initiates the release of ECM molecules from artificially demineralized human dentin. Analysis of the supernatants by Western blotting reveals that MMP-3 extracts PGs (decorin, biglycan), and also a series of phosphorylated proteins: dentin sialoprotein (DSP), osteopontin (OPN), bone sialoprotein (BSP) and MEPE, but neither dentin matrix protein-1 (DMP1), another member of the SIBLING family, nor osteocalcin (OC), a non-phosphorylated matrix molecule. After treatment of dentin surfaces by MMP-3, scanning electron microscope (SEM) examination of resin replica shows an increased penetration of the resin into the dentin tubules when compared to surfaces only treated by demineralizing solutions. This preclinical investigation suggests that MMP-3 may be used to improve the adhesive properties of restorative materials.

Antigenic profile, prevalence, and clinical significance of antiphospholipid antibodies in women referred for in vitro fertilization

The aim of this prospective study was to assess the prevalence of antiphospholipid antibodies (aPL) in women who had undergone in vitro fertilization (IVF) and the relationship between aPL and IVF outcome. A total of 101 infertile women with at least three unsuccessful IVF attempts were consecutively included in this study. Samples were collected in the follicular phase of a spontaneous ovarian cycle 2 months after the last ovulation induction treatment. Age-matched healthy fertile women (n = 160) were included as controls. All were evaluated for the presence of lupus anticoagulant (LA), antibodies (IgG, IgA, IgM) to cardiolipin (aCL), beta2-glycoprotein I (abeta2GPI), and phosphatidylethanolamine (aPE). Out of the 101 infertile women, 40 were persistently positive for aPL, showing a prevalence significantly higher than in controls (39.6% versus 5%, P < 0.0001). Among aPL, aPE were found with a significantly higher prevalence compared with LA, aCL, and aP2GPI (67.5% versus 0%, 15%, and 40%, respectively). Interestingly, aPE were found in 70% of the cases in the absence of the other aPL. The predominant isotype of aPL was IgA, in particular for abeta2GPI. Finally, no significant association was found between the presence of aPL and IVF outcome. This prospective study shows aPE as the most prevalent aPL in infertile women and IgA as more common than IgG and IgM. However, our results do not support an association between aPL and IVF outcome.

Étude de l'association hépatite auto-immune et antiphospholipides

INTRODUCTION

Only few series have reported the association of autoimmune hepatitis with antiphospholipid antibodies. The aim of our study is to investigate the frequency of these antibodies in a series of autoimmune hepatitis and to search for a correlation with clinical, biological or histological characteristics.

MATERIAL AND METHODS

Antiphospholipid were investigated in 24 patients with well defined autoimmune hepatitis. Characteristics were compared between antiphopholipids positive and negative patients. Characteristics of our patients were also compared toward cases collected in a literature review.

RESULTS

The frequency of antiphospholipid antibodies is of 70.8% in our series. Four patients had a well defined antiphospholid syndrome. Seven patients had a systemic lupus erythematosus in the antiphospholipid group whereas none in the antiphospholipid negative group. The frequency of the different antiphopholipid antibodies was: IgG ACL (52.9%), IgM APE (52.9%), ACC (43.7%), IgG Abeta2GP1 (41.2%). We found no correlation between hypergammaglobulinemia and the presence or the isotype of antiphospholipid antibodies. Clinical presentation and outcome as biological and histological parameters were similar in both groups.

CONCLUSION

Our study report a high frequency of antiphospholipids antibodies in autoimmune hepatitis patients. However we found no clinical, biological or histological correlation with the presence of antiphospholipids. Further longitudinal studies on larger cohorts should clarify the association between antiphospholipid antibodies and autoimmune hepatitis and potential therapeutic issues.

Le syndrome MYH9 : à propos d'une nouvelle observation et de la mise en évidence d'une nouvelle mutation du gène MYH9

INTRODUCTION

Familial macrothrombocytopenias are a group of rare autosomal dominant platelet disorders including many syndromes in particular the May-Hegglin anomaly. They are characterized by thrombocytopenia with giant platelets and in some cases neutrophilic inclusions in peripheral blood granulocytes. Recently these different clinical entities have been demonstrated to be linked to mutations in the same gene, MYH9.

CASE REPORT

We report in a young African woman presenting as a May-Hegglin anomaly a new mutation of the MYH9 gene. In regard of this case we present a brief review of the MYH9 syndrome.

CONCLUSION

The MYH9 syndrome includes now several clinical entities who share some common clinical and biological characteristics such as a thrombocytopenia with giant platelets, presence or absence of other manifestations including Dohle like bodies, nephritis, sensorineural hearing loss, cataract. We report a new case in which a new mutation of the MYH9 gene was evidenced.

The formation of an intrachain disulfide bond in the leptin protein is necessary for efficient leptin secretion

Leptin is a cytokine secreted by the adipose tissue that is involved in the control of body weight. We previously showed that a point mutation (R105W) in leptin results in leptin deficiency, marked obesity and hypogonadism in humans adults. Expression in COS1 cells showed impaired secretion and intracellular accumulation of the mutated protein. However, impaired secretion of the mutant leptin had not been demonstrated in adipose cells. In this work, we demonstrate that secretion of R105W mutant is impaired in rat and human adipocytes. We also show that R105W mutant expressed in COS1 cells and in PAZ6 adipocytes forms large molecular aggregates that cannot cross a filtration membrane with a cut-off of 100 kDa. Moreover, we have engineered, by site directed mutagenesis, the cDNAs coding for leptin in which either Cys 117, Cys 167, or both, were replaced by a serine. When expressed in COS1 cells or PAZ6 adipocytes, cysteine mutants also show impaired secretion and formation of large molecular aggregates. Therefore, our work indicates that the formation of an intramolecular disulfide bridge is necessary for normal processing and secretion of leptin. Moreover, the similarity of the behavior of R105W mutant and cystein mutants suggests that the lack of secretion observed with the naturally occurring mutant could result from impaired disulfide bond formation.

Serum leptin activity in obese and lean patients

Blood levels of the satiety hormone leptin are directly correlated to fat stores in obese and lean people. Therefore, leptin resistance is the logical explanation for the phenomenon of common obesity. However, the important question of whether or not the intrinsic leptin activity could differ between obese and lean people has not been examined before. In the present study, serum leptin activity was measured by an in vitro assay of leptin signaling in a modified culture of HEK-293 cells. The system is based on activation of a luciferase reporter gene through a leptin receptor-dependent activation of the signal transducer and activator of transcription (STAT3). Serum samples from 20 obese and 20 non-obese individuals with leptin levels ranging from 3 to 75 ng/ml, as determined by radioimmunoassay (RIA), were used. A high correlation was observed for each serum sample between leptin RIA values and leptin activity in the bioassay. The results indicate that obesity in the 20 obese patients among the 40 individuals examined cannot be accounted for by alterations in leptin activity in our assay. The assay system provides a tool to screen for possible rare cases exhibiting alteration in leptin activity either due to a change in leptin itself or through interaction with other serum factors.

Study of antigen-processing steps reveals preferences explaining differential biological outcomes of two HLA-A2-restricted immunodominant epitopes from human immunodeficiency virus type 1

Cytotoxic T-lymphocyte (CTL) responses directed to different human immunodeficiency virus (HIV) epitopes vary in their protective efficacy. In particular, HIV-infected cells are much more sensitive to lysis by anti-Gag/p17(77-85)/HLA-A2 than to that by anti-polymerase/RT(476-484)/HLA-A2 CTL, because of a higher density of p17(77-85) complexes. This report describes multiple processing steps favoring the generation of p17(77-85) complexes: (i) the exact COOH-terminal cleavage of epitopes by cellular proteases occurred faster and more frequently for p17(77-85) than for RT(476-484), and (ii) the binding efficiency of the transporter associated with antigen processing was greater for p17(77-85) precursors than for the RT(476-484) epitope. Surprisingly, these peptides, which differed markedly in their antigenicity, displayed qualitatively and quantitatively similar immunogenicity, suggesting differences in the mechanisms governing these phenomena. Here, we discuss the mechanisms responsible for such differences.

[Retrospective study of 55 patients with circulating blood T gama/delta lymphocytosis]

PURPOSE

Gamma/delta T lymphocytes constitute a singular population due to their particular antigenic recognition and their localization inside the epithelium. Their functions are complementary to those of the alpha/beta T-cells and they are involved in the defense and regulation of the immune system. Their role in human diseases is not very well understood and the aim of our study was to analyze a population of patients with a peripheral gamma/delta T-cell lymphocytosis.

METHODS

The study included 55 patients, recruited from 1997 to 2000, with a peripheral gamma/delta T lymphocytosis (defined by a proportion of gamma/delta T-cells of over 10% of total peripheral T lymphocytes). Analysis of the lymphocyte population was obtained by cytometry after peripheral blood sampling.

RESULTS

Three main groups of diseases were observed: infectious diseases (viral infections and tuberculosis), inflammatory diseases (sarcoidosis and autoimmune diseases) and blood diseases (monoclonal gammopathies and hemopathies). Persistence of gamma/delta T lymphocytosis was dependent on the underlying disease (transitional when associated with an infectious disease and lasting when associated with sarcoidosis). The rest of the immunophenotyping analysis was usually normal.

CONCLUSION

Our results confirm the data published in the literature concerning the role of the gamma/delta T lymphocytes in infectious, inflammatory and autoimmune diseases and neoplasias. These data are in agreement with the cytotoxic and regular functions of these lymphocytes.

The iodocyanopindolol and SM-11044 binding protein belongs to the TM9SF multispanning membrane protein superfamily

SM-11044 is the only beta-adrenergic agonist that inhibits guinea pig eosinophil chemotaxis and induces relaxation of depolarized rat colon tonus. We have previously reported the purification of a 34 kDa photoaffinity-labeled SM-11044 binding protein (SMBP) from rat colon that may mediate the biological effects of the ligand and that differs from all known monoamine receptors (Sugasawa et al., J. Biol. Chem. 272 (1997) 21244). The present report describes partial amino acid sequence of rat SMBP and molecular cloning of corresponding human SMBP (hSMBP) cDNA. This cDNA encodes a 588 amino acid residue polypeptide comprising a signal peptide, a long hydrophilic amino-terminal region, and a highly hydrophobic C-terminal portion organized into nine putative transmembrane domains. The sequence and structure of hSMBP shows homology to members of a new transmembrane protein 9 superfamily (TM9SF). Comparison of hSMBP with related protein sequences from yeast, plant and human revealed two subgroups within TM9SF. The members of these groups differ in length and have characteristic amino acid sequence motifs in their amino-terminal portion. Northern blot analysis revealed two major SMBP mRNAs, at 3.4 and 3.8 kb, that were present in all the human tissues examined. Western blot experiments detected SMBP as a 70 kDa protein that may be further cleaved into an active 34 kDa N-terminal polypeptide. Stable Chinese Hamster Ovary cell transfectants expressing hSMBP cDNA displayed specific binding of [(125)I]iodocyanopindolol that was displaced by SM-11044 in a dose-dependent manner. Thus, SMBP is the first member of TM9SF with functional ligand binding properties, suggesting that some of these integral membrane proteins may function as channels, small molecule transporters or receptors.

Chemokines control fat accumulation and leptin secretion by cultured human adipocytes

In addition to their role in inflammation, cytokines like TNFalpha have been reported to regulate the adipose tissue function suggesting a role for these soluble mediators in metabolism. However, it is not known whether adipocytes have the capacity to secrete chemokines, a group of low molecular weight inflammatory mediators that control leukocyte migration into tissues. Here we show that primary cultures of human preadipocytes constitutively produce three chemokines, interleukin-8 (IL-8), macrophage inflammatory protein-1alpha (MIP-1alpha) and monocyte chemotactic protein-1 (MCP-1), while their level of expression is low in mature adipocytes. Upon TNFalpha treatment, the expression of all the three chemokines is upregulated in adipocytes differentiated in vitro. In addition, we describe the presence of seven different chemokine receptors, mainly in mature adipocytes, both in vitro and in human fat tissue sections. Prolonged stimulation of cultured human adipocytes with exogenous chemokines leads to a decrease in lipid content in association with the downregulation of PPARgamma mRNA expression. Moreover, chemokines positively control the secretion of leptin, a hormone that regulates appetite, by a post-transcriptional mechanism. These findings reveal a new role for chemokines in the regulation of adipose tissue and suggest a novel therapeutic basis for the treatment of obesity, diabetes and cachexia.

Genetic variation in the stress protein hsp70-2 gene is highly associated with obesity

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) expression is increased in adipose tissue of both rodent models of obesity and obese humans. It has therefore been considered as a candidate gene for obesity. Several studies have indeed shown statistical evidence of linkage between obesity and the chromosomal region encompassing the TNF-alpha gene, suggesting that TNF-alpha and/or a nearby gene (eg hsp70 gene) is involved in the onset and progression of weight gain. We designed a case-controlled study to investigate the potential association of polymorphism of the TNF-alpha and that of a stress protein (hsp70-2) with obesity.

METHODS

We used the polymerase chain reaction and restriction enzyme digestion to characterize the variation of the TNF-alpha promoter region and that of the hsp70-2 gene in 343 unrelated Tunisian patients with obesity and 174 healthy control subjects.

RESULTS

Analysis of the -308 TNF-alpha polymorphism in patients with obesity and in control subjects did not reveal an association between TNF-alpha alleles and obesity. In contrast, polymorphism analysis of the hsp70-2 gene in patients with obesity demonstrated highly significant differences in genotypic distribution of this bi-allelic locus compared to the control subject group. Homozygosity for one hsp70-2 allele was highly associated with obesity (r2=7.12; P<10(-6)).

CONCLUSION

Tunisian persons carrying the P2/P2 genotype of the hsp70-2 gene may have an increased risk of obesity.

Substituting selenocysteine for catalytic cysteine 41 enhances enzymatic activity of plant phospholipid hydroperoxide glutathione peroxidase expressed in Escherichia coli

The citrus phospholipid hydroperoxide glutathione peroxidase (cit-PHGPx) was the first plant peroxidase demonstrated to exhibit PHGPx-specific enzymatic activity, although it was 500-fold weaker than that of the pig heart analog. This relatively low activity is accounted for the catalytic residue of cit-PHGPx, which was found to be cysteine and not the rare selenocysteine (Sec) present in animal enzymes. Sec incorporation into proteins is encoded by a UGA codon, usually a STOP codon, which, in prokaryotes, is suppressed by an adjacent downstream mRNA stem-loop structure, the Sec insertion sequence (SECIS). By performing appropriate nucleotide substitutions into the gene encoding cit-PHGPx, we introduced bacterial-type SECIS elements that afforded the substitution of the catalytic Cys(41) by Sec, as established by mass spectrometry, while preserving the functional integrity of the peroxidase. The recombinant enzyme, whose synthesis is selenium-dependent, displayed a 4-fold enhanced peroxidase activity as compared with the Cys-containing analog, thus confirming the higher catalytic power of Sec compared with Cys in cit-PHGPx active site. The study led also to refinement of the minimal sequence requirements of the bacterial-type SECIS, and, for the first time, to the heterologous expression in Escherichia coli of a eukaryotic selenoprotein containing a SECIS in its open reading frame.

In vitro generation of endothelial microparticles and possible prothrombotic activity in patients with lupus anticoagulant

Microparticles (MPs) resulting from vesiculation of platelets and other blood cells have been extensively documented in vitro and have been found in increased numbers in several vascular diseases, but little is known about MPs of endothelial origin. The aim of this study was to analyze morphological, immunological, and functional characteristics of MPs derived from human umbilical vein endothelial cells (HUVECs) stimulated by TNF, and to investigate whether these MPs are detectable in healthy individuals and in patients with a prothrombotic coagulation abnormality. Electron microscopy evidenced bleb formation on the membrane of TNF-stimulated HUVECs, leading to increased numbers of MPs released in the supernatant. These endothelial microparticles (EMPs) expressed the same antigenic determinants as the corresponding cell surface, both in resting and activated conditions. MPs derived from TNF-stimulated cells induced coagulation in vitro, via a tissue factor/factor VII-dependent pathway. The expression of E-selectin, ICAM-1, alphavbeta3, and PECAM-1 suggests that MPs have an adhesion potential in addition to their procoagulant activity. In patients, labeling with alphavbeta3 was selected to discriminate EMPs from those of other origins. We provide evidence that endothelial-derived MPs are detectable in normal human blood and are increased in patients with a coagulation abnormality characterized by the presence of lupus anticoagulant. Thus, MPs can be induced by TNF in vitro, and may participate in vivo in the dissemination of proadhesive and procoagulant activities in thrombotic disorders.

Copurification of selected glycolytic enzymes with retinal S-antigen (arrestin) by hydroxyapatite agarose chromatography of bovine retina

PURPOSE

A variety of methods have been developed for the purification of S-antigen but a simple and rapid procedure based on hydroxyapatite-agarose (HA) adsorbtion is most widely used. In the present study, we investigated the nature of proteins purified with the aid of HA chromatography.

METHODS

After elimination of retinal S-antigen by HA, the soluble extract of retinal tissue was readsorbed on HA. The proteins were thereafter desorbed by 10 to 500 mM phosphate buffer gradient. Two peaks obtained by SDS-PAGE were used for the generation of specific antisera for subsequent analysis by ELISA and Western blotting.

RESULTS

Four proteins (two 48 kDa , one 50 kDa and one 46 kDa) were obtained in this manner. Partial amino acid sequencing permitted the identification of these proteins as alpha-enolase (48 kDa), gamma-enolase (48 kDa), Glucose-6-phosphate-Isomerase (50 kDa) and aspartate-amino-transferase (46 kDa).

CONCLUSION

The selected glycolytic enzymes co-purified with retinal S-antigen by hydroxyapatite agarose chromatography of bovine retina.

Purification and identification of two putative autolytic sites in human calpain 3 (p94) expressed in heterologous systems

Human muscle-specific calpain (CAPN3) was expressed in two heterologous systems: Sf9 insect cells and Escherichia coli cells. Polyclonal antibodies were prepared against peptides whose sequences were taken from the three unique regions of human CAPN3, namely NS, IS1, and IS2, which are not found in other members of the calpain family. Western blot analysis using these antibodies revealed that CAPN3 was well expressed in both systems. However, considerable rapid degradation of the expressed CAPN3 was observed in both Sf9 and E. coli cells. These antibodies were therefore also used to detect CAPN3 and its degradation products in human and rat muscles, as well as to detect the protein throughout the purification of the recombinant His-tagged human CAPN3 by Ni2+ affinity chromatography and by immunopurification over immobilized antibody. An alternative purification procedure was used for purification of all putative CAPN3 immunoreactive fragments by combining SDS-PAGE and hydroxyapatite chromatography. Two fragments of CAPN3 of approximately 55 kDa were purified, and their N-terminal amino acid sequencing demonstrated that cleavage of CANP3 occurred between residues 30-31 and 412-413, thus providing the first evidence for the localization of putative autolytic sites in this enzyme.

Evidence for the expression of urokinase-type plasminogen activator by human venous endothelial cells in vivo

Endothelial cells (ECs) in culture synthesize and secrete urokinase-type plasminogen activator (u-PA), but the normal vascular endothelium is believed to synthesize only tissue plasminogen activator (t-PA), which is thought to be responsible for intravascular fibrinolysis. More recently, animal studies have shown that the biological role of u-PA in fibrinolysis has been underestimated, prompting a re-examination of its synthesis by the endothelium. In this study, we investigated whether u-PA was synthesized by non-atherosclerotic endothelial cells in vivo by testing ECs dislodged by venipuncture from 12 normal volunteers and 17 patients admitted for plasmapheresis. The ECs were isolated with an anti-endothelial monoclonal antibody coupled to immunomagnetic beads and characterized by morphology and by labelling for vWF, CD31, and UEA-1 binding. U-PA antigen was found in 50% of the ECs from the normal subjects and in 60% of those from patients. U-PA enzymatic activity on zymograms was detected in 50% of the normal samples and 60% of the patient samples, with the latter being more frequently and more strongly positive. U-PA mRNA was found in all the normal and patient samples tested. The results indicate that u-PA is synthesized by the venous endothelium in vivo but that its expression is highly variable.

Human preformed IgG combining with membrane-bound porcine serotransferrin lyse porcine endothelial cells through antibody-dependent cellular cytotoxicity

Preformed antibodies are involved in xenograft rejection. The purpose of this work was to characterize porcine xenoantigens recognized by human preformed IgG (hpIgG), and to investigate the role of hpIgG in xenogeneic rejection. IgG eluted from porcine livers perfused with human plasma, human sera and total human IgG were immunoblotted on porcine aortic endothelial cell extracts. The amino acid sequence of a 76-kDa antigen constantly revealed was 100% homologous with porcine serotransferrin (psTf). hpIgG from human sera, human IgG1 and IgG2 and F(ab')2gamma specifically bound to psTf. Neutralization by psTf abolished that binding. Although alpha1,3-linked galactose residues (Gal(alpha)1,3Gal) is the dominant epitope recognized by preformed antibodies in the swine-to-human combination, the analysis of carbohydrate composition of psTf showed that the molecule was devoid of Gal(alpha)1,3Gal moieties and that preformed anti-psTf IgG bound to epitopes localized on the peptide core of the molecule. Purified human anti-psTf IgG antibodies were able to bind to psTf linked to its receptor on porcine endothelial cells, and to kill those cells through antibody-dependent cellular cytotoxicity.

Purification and characterization of equine testicular cytochrome P-450 aromatase: comparison with the human enzyme

Cytochrome P-450 aromatase was purified by five chromatographic steps from adult stallion testis. It was first separated from NADPH-cytochrome P-450 reductase (reductase) on omega-aminohexyl-Sepharose 4B then purified to homogeneity on concanavalin A-Sepharose 4B, hydroxyapatite-Sepharose 4B, DEAE-Sepharose CL-6B and on a second hydroxyapatite-Sepharose 4B. On the other hand, purifications of the equine testicular and rat liver reductases, which allowed the reconstitution of aromatase activity in vitro, were achieved for each species in one chromatographic step on an adenosine 2',5'-diphosphate-agarose affinity column. Analysis on SDS/PAGE indicated single bands with apparent molecular masses of 53, 82, and 80 kDa for purified equine testicular cytochrome P-450 aromatase (eAROM), equine testicular reductase and rat liver reductase respectively. eAROM shows a time- and concentration-dependent activity that was stable for at least 2 months when stored at -78 degrees C. It is a highly hydrophobic protein composed from 505 residues and direct sequencing of its N-terminal part showed good homology when compared with human aromatase. When deglycosylated by N-glycosidase-F the apparent molecular mass of eAROM was decreased from 53 to 51 kDa as revealed by electrophoresis, its activity, however, was not impaired. eAROM exhibits much higher affinity for androgens than for 19-norandrogens, Km values were approximately 3, 16 and 170 nM for androstenedione (A), testosterone (T) and 19-nortestosterone (19-NT) respectively. However, it aromatizes 19-norandrostenedione (19-NA) slightly more efficiently than A, the estrone (E1) formed was 4.27 vs 3.54 pmol min-1 micrograms-1 respectively (P < 0.01). After incubation of eAROM with radiolabelled A and separation of steroids on HPLC, E1, 19-hydroxyandrostenedione (19-OHA) and 19-oxoandrostenedione (19-oxoA) were accumulated in the incubation medium in a time-dependent manner. The presence of 4-hydroxyandrostenedione (4-OHA), a suicide inhibitor of aromatase, cause a time-dependent inactivation of the enzyme. Whereas the activity of eAROM was unchanged in the presence of K+ (up to 250 mM), it was increased in the presence of EDTA (up to 50 mM) and decreased in the presence of DTT or Mg2+ (from 25 mM). We conclude that: (a) eAROM is a glycoprotein, however, deglycosylation by N-glycosidase-F does not appear to impair its activity, (b) eAROM aromatizes really both androgens and 19-norandrogens having a higher affinity for androgens, (c) the intermediary compounds of aromatization 19-OHA and 19-oxoA appear to be synthesized by the same active site that synthesizes E1 as the final product, (d) the inhibition of eAROM by increasing concentrations of Mg2+ and the stimulation of its activity by EDTA, taken together, indicate the importance of negatively charged residues in the polypeptide chain of equine aromatase, which play a role in enzymatic activity.

Characterization of a novel iodocyanopindolol and SM-11044 binding protein, which may mediate relaxation of depolarized rat colon tonus

Studies under blockade of alpha-, beta1-, and beta2-adrenoreceptors revealed a good correlation between the responses of rat colon relaxation of depolarized tonus and of rat adipocyte lipolysis elicited by catecholamines or BRL-37344, a selective beta3-adrenoreceptor agonist, suggesting beta3-adrenoreceptor stimulation. In contrast, SM-11044, a nonselective beta-adrenoreceptor agonist, stimulated colon relaxation more efficiently than lipolysis; its effects were differently antagonized by cyanopindolol with pA2 values of 8.31 in colon and of 7.32 in adipocytes. Binding studies in rat colon smooth muscle membranes using [125I]iodocyanopindolol under blockade of adrenaline and serotonin receptors revealed the existence of a single class of sites (Kd = 11.0 nM, Bmax = 716.7 fmol/mg protein). The specific binding was saturable and reversible and was displaced by SM-11044 but not by BRL-37344, isoproterenol, noradrenaline, adrenaline, serotonin, nor dopamine. This binding site was photoaffinity labeled using [125I]iodocyanopindolol-diazirine. The labeling was prevented by SM-11044 but not by BRL-37344. The amino-terminal amino acid sequences of the high performance liquid chromatography-purified peptides generated by enzymatic and chemical cleavages of the affinity labeled 34-kDa protein confirmed that the novel iodocyanopindolol or SM-11044 binding protein of rat colon smooth muscle membranes is different from known adrenaline, serotonin, or dopamine receptors. Its functional role might include the relaxation of depolarized colon.

Amino acid sequence and three-dimensional structure of the Tn-specific isolectin B4 from Vicia villosa

The partial amino acid sequence of the tetrameric isolectin B4 from Vicia villosa seeds has been determined by peptide analysis, and its three-dimensional structure solved by molecular replacement techniques and refined at 2.9 A resolution to a crystallographic R-factor of 21%. Each subunit displays the thirteen-stranded beta-barrel topology characteristic of legume lectins. The amino acid residues involved in metal- and sugar-binding are similar to those of other GalNAc-specific lectins, indicating that residues outside the carbohydrate-binding pocket modulate the affinity for the Tn glycopeptide. Isolectin B4 displays an unusual quaternary structure, probably due to protein glycosylation.

Association of the cytoplasmic domain of intercellular-adhesion molecule-1 with glyceraldehyde-3-phosphate dehydrogenase and beta-tubulin

To elucidate the molecular mechanisms of the transendothelial migration of leukocytes, we attempted to identify the cellular proteins capable of interaction with the cytoplasmic domain of the intercellular adhesion molecule-1 (ICAM-1) in a rat brain microvessel endothelial cell line (RBE4 cells). A 27-amino-acid synthetic peptide, corresponding to the cytoplasmic domain of rat ICAM-1, was covalently linked to a Sepharose matrix. Upon affinity chromatography of RBE4 cell cytosol, several ICAM-1-interacting proteins were specifically eluted by the soluble peptide. Two of these proteins have been identified by microsequencing as the cytoskeletal protein beta-tubulin and the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GraP-DH). Experiments carried out with purified GraP-DH or CNBr fragments of GraP-DH indicated that binding to the ICAM-1 matrix was mediated by the C-terminal domain of GraP-DH, containing the binding site of the cofactor NAD+, and that NAD+ could compete with this binding. Using a series of ICAM-1 C-terminal truncated peptides, we could demonstrate that (a) the nitric-oxide-induced covalent linkage of NAD+ to GraP-DH was impaired by these peptides, (b) the glycolytic activity of GraP-DH was drastically inhibited by a truncated peptide containing the 15 C-terminal residues, (c) nitric oxide appeared to prevent this inhibition. Together, our results demonstrate that GraP-DH specifically associates with the isolated ICAM-1 cytoplasmic domain. Since GraP-DH is known as a microtubule bundling protein, these findings suggest that, in a cellular environment, GraP-DH may behave as an adaptor molecule by linking ICAM-1 to the microtubule network. The role of nitric oxide in the modulation of this interaction deserves further investigation.

Structural analysis of the principal immunodominant domain of the feline immunodeficiency virus transmembrane glycoprotein

In the transmembrane envelope glycoprotein (TM) of lentiviruses, including human immunodeficiency virus type 1 (HIV-1) and feline immunodeficiency virus (FIV), two cysteine residues, conserved in most retroviruses, are thought to form a loop containing five to seven amino acids. These elements make up a B-cell epitope recognized by nearly 100% of sera from infected patients or animals, designated the principal immunodominant domain (PID). The PID amino acid sequences are highly conserved between isolates of the same lentivirus but are unrelated, except for the two cysteines, when divergent lentiviruses are compared. The aim of this study was to analyze the relationship between amino acid sequence in the PID and envelope function. We introduced two kinds of mutations in the PID of FIV: mutations which impeded the formation of a loop and mutations which substituted the sequence of FIV with the corresponding sequences from other lentiviruses, HIV-1, visna virus, and equine infectious anemia virus. We analyzed antibody recognition, processing, and fusogenic properties of the modified envelopes, using two methods of Env expression: a cell-free expression system and transfection of a feline fibroblast cell line with gag-pol-deleted FIV proviruses. Most mutations in the PID of FIV severely affected envelope processing and abolished syncytium formation. Only the chimeric envelope containing the HIV-1 PID sequence was correctly processed and maintained the capacity to induce syncytium formation, although less efficiently than the wild-type envelope. We computed three-dimensional structural models of the PID, which were consistent with mutagenesis data and confirmed the similarity of FIV and HIV-1 PID structures, despite their divergence in amino acid sequence. Considering these results, we discussed the respective importance of selection exerted by functional requirements or host antibodies to explain the observed variations of the PIDs in lentiviruses.

Cultured astrocytes release a factor that decreases endothelin-1 secretion by brain microvessel endothelial cells

Endothelin-1 (ET-1), originally characterized as a potent vasoconstrictor peptide secreted by vascular endothelial cells, has now been described to possess a wide range of biological activities within the cardiovascular system and in other organs. Brain microvessel endothelial cells, which, together with perivascular astrocytes, constitute the blood-brain barrier, have been shown to secrete ET-1, whereas specific ET-1 receptors are expressed on astrocytes. It is reported here that conditioned medium from primary cultures of mouse embryo astrocytes could significantly, and reversibly, attenuate the accumulation of both ET-1 and its precursor big ET-1 in the supernatant of rat brain microvessel endothelial cells by up to 59 and 76%, respectively, as assessed by immunometric assay. This inhibitor of ET-1 production was purified by gel-exclusion and ion-exchange chromatography as a 280-Da iron-containing molecule, able to release nitrites upon degradation. These results suggest that astrocytes, via release of an iron-nitrogen oxide complex, may be involved in a regulatory loop of ET-1 production at the level of the blood-brain barrier.

Tyr394 and Tyr505 are autophosphorylated in recombinant Lck protein-tyrosine kinase expressed in Escherichia coli

The activity of the Src family protein-tyrosine kinase p56lck is regulated by phosphorylation and dephosphorylation of two critical tyrosine residues Tyr394 and Tyr505. Tyr394 is autophosphorylated after p56lck activation, whereas phosphorylation of Tyr505 is believed to be due to p50csk which negatively modulates p56lck activity. To determine whether Tyr505 could be autophosphorylated, we used the prokaryotic glutathione S-transferase expression system to express wild-type Lck, the mutants [Y394F]Lck and [Y505F]Lck, a kinase-deficient p56lck with a mutation of the ATP-binding site [K273E]Lck and a double mutant [Y394F, Y505F]Lck. We studied the kinase activities and the patterns of autophosphorylation for tyrosine residues in these mutants and wild-type Lck both in vivo and in vitro. Wild-type Lck, [Y505F]Lck and [Y394F]Lck were phosphorylated on tyrosine. Both the kinase-deficient mutant[K273E]Lck and the double mutant [Y394F, Y505F]Lck did not react with monoclonal anti-phosphotyrosine antibody [anti-Y(P) mAb], thus providing evidence that (a) the bacterial strains used lacked intrinsic protein-tyrosine kinase activities, and therefore tyrosine phosphorylations of wild-type Lck, [Y505F]Lck and [Y394F]Lck are due to autophosphorylation occurring in vivo in bacteria, and (b) that p56lck can only be autophosphorylated on two tyrosine residues, namely Tyr394 and Tyr505. Phosphopeptide mapping analysis confirmed that p56lck can undergo autophosphorylation on these two tyrosine residues. We propose that autophosphorylation at Tyr505 of p56lck may represent an accessory mechanism for the down-regulation of the tyrosine kinase activity of p56lck.

Purification of the plasmin receptor from human carcinoma cells and comparison to alpha-enolase

We have characterized a receptor for plasmin (Pli-R) from a human tumor cell line, MCF7MF. The Pli-R was purified from a MCF7 0.1% Triton X-100 solubilisate by affinity chromatography. A protein of 55-60 kDa was obtained, which bound plasminogen and plasmin specifically. Chemical cross-linking of M(r) 90 kDa [125I]-Pli to the surface of MCF7 cells with DSP results in the formation of a labelled complex of M(r) 145 kDa, suggesting a M(r) of 55-60 kDa for the receptor. Comparing Pli-R with alpha-enolase (a candidate for plasminogen receptor in U937 cells) we have found a high homology between both proteins, but not an identity.

The origin of the diversity of crotoxin isoforms in the venom of Crotalus durissus terrificus

Crotoxin, the main toxin from the venom of the South American rattlesnake Crotalus durissus terrificus, is a beta-neurotoxin which consists of the non-covalent association of two subunits: a phospholipase A2 subunit B (CB), and a non-enzymic subunit A (CA). We have previously purified and characterized several isoforms of each subunit of crotoxin in the venom collected from numerous snakes. Furthermore, three cDNAs encoding two CB isoforms and the precursor, pro-CA, of subunit A have been isolated from a cDNA library prepared from a single venom gland of Crotalus durissus terrificus. The aim of this study is to analyse an individual snake venom from an animal that has been used to construct a cDNA library. Several isoforms of subunit A and two isoforms of subunit B were isolated and compared to purified and characterized subunit isoforms from pooled venom. The result of this study showed that the multiplicity and the diversity of crotoxin isoforms result from post-translational modifications occurring on a precursor and from the expression of different messenger RNAs present in an individual snake. It allowed for the identification of the two CB isoforms encoding cDNAs expressed in the individual venom with two isoforms from pooled venom, CBc and probably CBa2, that belong to two classes of crotoxin complexes which can be distinguished biochemically and pharmacologically.