BaG, a new dimeric metalloproteinase/disintegrin from the Bothrops alternatus snake venom that interacts with alpha5beta1 integrin

Cell-Based Adhesion Assays for Isolation of Snake Venom's Integrin Antagonists

Snake venoms could lead to the development of new drugs to treat a range of life-threatening conditions like cardiovascular diseases. Most snake venoms contain a large variety of lethal toxins as well as anti-adhesive proteins such as disintegrins, which have evolved from the harmless compounds ADAMs (proteins with a disintegrin and a metalloprotease domain) and C-type lectin proteins which disturb connective tissue and cell-matrix interaction. These anti-adhesive proteins target and block integrin receptors and disrupt normal biological processes in snakes' prey such as connective tissue physiology and blood clotting. This chapter provides the experimental details of a practical, cell-based adhesion protocol to help identify and isolate disintegrins and C-type lectin proteins from snake venoms, important tools in integrin research and lead compounds for drug discovery.

Venoms and Isolated Toxins from Snakes of Medical Impact in the Northeast Argentina: State of the Art. Potential Pharmacological Applications

Among the ophidians that inhabit the Northeast of Argentina, the genus Bothrops such as B. alternatus and B. diporus species (also known as yararás) and Crotalus durisus terrificus (named cascabel), represent the most studied snake venom for more than thirty years. These two genera of venomous snakes account for the majority of poisonous snake envenomations and therefore, constitute a medical emergency in this region. This review presents a broad description of the compiled knowledge about venomous snakebite: its pathophysiological action, protein composition, isolated toxins, toxin synergism, toxin-antitoxin cross-reaction assays. Properties of some isolated toxins support a potential pharmacological application.

Heparin-grafted PVA hydrogels: a material for the optical part of artificial cornea

Heparin (Hep) was grafted to a poly(vinyl alcohol) (PVA) hydrogel surface by using the covalent grafting method. The structure of the modified hydrogel was determined from Fourier transform infrared attenuated total reflection and X-ray photoelectron spectroscopy. The thermal stability of the samples was investigated by thermogravimetry–differential thermal analysis. The effects of the concentration of (3-aminopropyl)triethoxysilane (kh550) and Hep on visible light transmittance, moisture content, equilibrium swelling, hydrophilicity and percentage of Hep sodium release of the composite hydrogel were studied. The visible light transmittance of the modified PVA hydrogel was above 94%. The time of swelling equilibrium was about 60 min and the equilibrium swelling ratio ranged from 3·0 to 3·5. The hydrophilicity was enhanced, and the static water contact angle decreased from 41 to 28°. The bioeffects of the PVA–kh550–Hep hydrogel were evaluated by studying cell adhesion and proliferation. During the adhesion assay in vitro, cell adhesion significantly decreased after the interfaces had been modified with Hep. The Cell Counting Kit-8 assay showed that the biocompatibility of the PVA–kh550–Hep hydrogel improved obviously compared to that of pure PVA. The experimental results demonstrated that the PVA–kh550–Hep hydrogel had good stability, bioactivity and biocompatibility, suggesting its potential applications in artificial corneas.

Venom as therapeutic weapon to combat dreadful diseases of 21st century: A systematic review on cancer, TB, and HIV/AIDS

Cancer and infectious diseases are the preeminent causes of human morbidities and mortalities worldwide. At present, chemotherapy, radiotherapy, immunotherapy, and gene therapy are considered as predominant options in order to treat cancer. But these therapies provide inadequate consequences by affecting both the normal and tumor cells. On the other hand, tuberculosis (TB), and HIV (human immunodeficiency virus) infections are significant threats, causing over a million mortalities each year. The extensive applications of antibiotics have caused the microbes to acquire resistance to the existing antibiotics. With the emerging dilemma of drug resistant microbes, it has become imperative to identify novel therapeutic agents from natural sources as emphatic alternative approach. Over the past few decades, venoms derived from several reptiles, amphibians, and arthropods including snakes, scorpions, frogs, spiders, honey bees, wasps, beetles, caterpillars, ants, centipedes, and sponges have been identified as efficient therapeutics. Venoms constitute plethora of bioactive components, particularly peptides, enzymes, and other chemical entities, which exhibit a large array of anticancer and anti-pathogenic activities. This review highlights the panorama of bioactive components of animal venoms divulging the anticancer, anti-tubercular, and anti-HIV activities. In a nutshell, this context discloses the decisive role of animal venoms as alternative natural resources to combat these deadly diseases of 21^st century, and propounding the plausible development of new therapeutic drugs in the present era.

Cytotoxicity and anti-tumor effects of new ruthenium complexes on triple negative breast cancer cells

Triple-negative breast cancer (TNBC) is a highly aggressive breast cancer subtype. The high rate of metastasis associated to the fact that these cells frequently display multidrug resistance, make the treatment of metastatic disease difficult. Development of antitumor metal-based drugs was started with the discovery of cisplatin, however, the severe side effects represent a limitation for its clinical use. Ruthenium (Ru) complexes with different ligands have been successfully studied as prospective antitumor drugs. In this work, we demonstrated the activity of a series of biphosphine bipyridine Ru complexes (1) [Ru(SO4)(dppb)(bipy)], (2) [Ru(CO3)(dppb)(bipy)], (3) [Ru(C2O4)(dppb)(bipy)] and (4) [Ru(CH3CO2)(dppb)(bipy)]PF6 [where dppb = 1,4-bis(diphenylphosphino)butane and bipy = 2,2'-bipyridine], on proliferation of TNBC (MDA-MB-231), estrogen-dependent breast tumor cells (MCF-7) and a non-tumor breast cell line (MCF-10A). Complex (4) was most effective among the complexes and was selected to be further investigated on effects on tumor cell adhesion, migration, invasion and in apoptosis. Moreover, DNA and HSA binding properties of this complex were also investigated. Results show that complex (4) was more efficient inhibiting proliferation of MDA-MB-231 cells over non-tumor cells. In addition, complex (4) was able to inhibit MDA-MB231 cells adhesion, migration and invasion and to induce apoptosis and inhibit MMP-9 secretion in TNBC cells. Complex (4) should be further investigated in vivo in order to stablish its potential to improve breast cancer treatment.

Associação de plasma sanguíneo ao tratamento de envenenamento botrópico em equino: relato de caso

RESUMO O presente trabalho tem por objetivo relatar um caso de envenenamento botrópico em um equino, fêmea, seis anos de idade, da raça Quarto de Milha, pesando 460kg, que foi atendido no hospital veterinário da FCAV/Unesp, Campus de Jaboticabal, SP. No exame clínico, observou-se aumento bilateral de narina, com extrema sensibilidade ao toque, presença das marcas da presa da serpente na região rostral de focinho, mucosas róseas com petéquias. No exame de sangue, pôde-se detectar alteração no tempo de coagulação sanguínea (>30 minutos). O animal permaneceu internado, sendo instituída a seguinte terapia: soro antiofídico polivalente, transfusão de plasma sanguíneo equino, fluidoterapia intensa, flunixin meglumine e sulfa associado ao trimetoprim. A associação da transfusão de plasma sanguíneo equino ao tratamento convencional foi de extrema importância para correção da coagulopatia causada pelo acidente ofídico. A égua apresentou melhora clínica e resolução do quadro de envenenamento após cinco dias da internação.

Distal M domain of cobra ADAM-like metalloproteinase mediates the binding of positively charged cysteine-rich domain to αvβ3 integrin in the suppression of cell migration

We have previously identified two new P-III type ADAM-like snake venom metalloproteinases (SVMPs), i.e., atragin and kaouthiagin-like, from Taiwan cobra venom and determined their 3D structures with a distinct C- and I-shaped metalloproteinase/disintegrin-like/cysteine-rich (MDC) modular architecture. Herein, we investigated their functional targets to elucidate the role of cobra SVMPs in perturbing wound healing in snakebite victims. We showed that the non-RGD (Arg-Gly-Asp) C-shaped SVMP atragin binds about ten-fold stronger than the RGD-containing I-shaped SVMP kaouthiagin-like to αvβ3 integrin in the surface-immobilized form. Atragin binds to αvβ3 integrin through a novel interaction mode involving distal M and C domains via the RRN sequence motif in the hyper variable loop. In a cell adhesion assay, the adhesion of fibroblasts to atragin was mediated by αvβ3 integrin. Furthermore, atragin inhibited wound healing and suppressed cell migration in a αvβ3 integrin-dependent manner. These results, together with our previous demonstration of non-cytotoxic cobra CTX A5 in targeting αvβ3 integrin, suggest that cobra venom consists of several non-RGD toxins with integrin-binding specificity that could perturb wound healing in snakebite victims.

A brief update on potential molecular mechanisms underlying antimicrobial and wound-healing potency of snake venom molecules

Infectious diseases remain a significant cause of morbidity and mortality worldwide. A wide range of diverse, novel classes of natural antibiotics have been isolated from different snake species in the recent past. Snake venoms contain diverse groups of proteins with potent antibacterial activity against a wide range of human pathogens. Some snake venom molecules are pharmacologically attractive, as they possess promising broad-spectrum antibacterial activities. Furthermore, snake venom proteins (SVPs)/peptides also bind to integrins with high affinity, thereby inhibiting cell adhesion and accelerating wound healing in animal models. Thus, SVPs are a potential alternative to chemical antibiotics. The mode of action for many antibacterial peptides involves pore formation and disruption of the plasma membrane. This activity often includes modulation of nuclear factor kappa B (NF-κB) activation during skin wound healing. The NF-κB pathway negatively regulates the transforming growth factor (TGF)-β1/Smad pathway by inducing the expression of Smad7 and eventually reducing in vivo collagen production at the wound sites. In this context, SVPs that regulate the NF-κB signaling pathway may serve as potential targets for drug development.

Phospholipase A(2) enhances the endothelial cell detachment effect of a snake venom metalloproteinase in the absence of catalysis

Microvessel disruption leading to hemorrhage stands among the most dangerous consequences of envenomings by snakes of the family Viperidae. A PIII metalloproteinase (SVMP), balteragin, purified from the venom of the snake Bothrops alternatus, displays a potent hemorrhagic effect, and a moderate myotoxicity in vivo. Previous studies described the ability of this SVMP to induce the detachment of C2C12 myoblasts in culture, without causing cytolysis. Surprisingly, a purified acidic phospholipase A2 (PLA2) from the same venom was found to increase this detaching activity of the SVMP on myoblasts. Since endothelial cells are a natural target of SVMPs in vivo, the possibility that this synergistic effect is also observed on this cell type was explored in the present work. In addition, a first approach of the mechanism of action of this effect was studied. Results clearly confirm that the acidic PLA2, despite lacking toxicity towards endothelial cells, significantly enhances the detaching effect of the SVMP even at a concentration as low as 1 μg/mL. Inhibition of enzymatic activity of the PLA2 by chemical modification with p-bromophenacyl bromide did not affect the synergistic activity, suggesting that this effect is not dependent on phospholipase enzymatic activity and may instead be the consequence of an interaction of the PLA2 with endothelial cell plasma membrane. To our knowledge, this is the first report of a synergistic action of a non toxic PLA2 in enhancing the detachment of endothelial cells induced by a metalloproteinase.

Elucidation of procoagulant mechanism and pathophysiological significance of a new prothrombin activating metalloprotease purified from Daboia russelii russelii venom

The procoagulant proteases present in Russell's Viper venom (RVV) are responsible for promoting consumption coagulopathy in victims. In this study, a procoagulant metalloprotease (Rusviprotease) possessing prothrombin activating and α-fibrinogenase properties has been purified and characterized from RVV. Rusviprotease is a 26.8 kDa glycoprotein which also exists in other multimeric forms. The peptide mass fingerprinting and secondary structure analyses of Rusviprotease revealed its similarity with snake venom prothrombin activators and metalloproteases. Similar to group A prothrombin activators, Rusviprotease cleaved prothrombin independent of any co-factor requirement generating meizothrombin which is further cleaved to form thrombin. The Km and Vmax values of Rusviprotease towards prothrombin were determined to be 1.73 μM, and 153.5 nM thrombin generated/min/μmoles of Rusviprotease, respectively. The Km and Vmax values of Rusviprotease towards fibrinogen were calculated to be 3.14 μM and 78.7 nmol/min, respectively. Spectrofluorometric study provided the evidence of interaction between Rusviprotease and factor Xa with a Kd value of 6.64 nM. This interaction augmented the prothrombin activating property of the factor Xa-prothrombinase-Rusviprotease complex by 2.5 fold. Intravenous injection of Rusviprotease to BALB/c mice (0.1 mg/kg) resulted in in vivo defibrinogenation rendering the blood incoagulable. In conclusion, Rusviprotease is the first example of a prothrombin activator with fibrinogenolytic property purified from Daboia russelii russelii venom.

Interrogating the Venom of the Viperid Snake Sistrurus catenatus edwardsii by a Combined Approach of Electrospray and MALDI Mass Spectrometry

The complete sequence characterization of snake venom proteins by mass spectrometry is rather challenging due to the presence of multiple isoforms from different protein families. In the present study, we investigated the tryptic digest of the venom of the viperid snake Sistrurus catenatus edwardsii by a combined approach of liquid chromatography coupled to either electrospray (online) or MALDI (offline) mass spectrometry. These different ionization techniques proved to be complementary allowing the identification a great variety of isoforms of diverse snake venom protein families, as evidenced by the detection of the corresponding unique peptides. For example, ten out of eleven predicted isoforms of serine proteinases of the venom of S. c. edwardsii were distinguished using this approach. Moreover, snake venom protein families not encountered in a previous transcriptome study of the venom gland of this snake were identified. In essence, our results support the notion that complementary ionization techniques of mass spectrometry allow for the detection of even subtle sequence differences of snake venom proteins, which is fundamental for future structure-function relationship and possible drug design studies.

Novel phospholipase A2 inhibitors from python serum are potent peptide antibiotics

Antimicrobial peptides (AMPs) play a vital role in defense against resistant bacteria. In this study, eight different AMPs synthesized from Python reticulatus serum protein were tested for bactericidal activity against various Gram-positive and Gram-negative bacteria (Staphylococcus aureus, Burkholderia pseudomallei (KHW and TES strains), and Proteus vulgaris) using a disc-diffusion method (20 μg/disc). Among the tested peptides, phospholipase A2 inhibitory peptide (PIP)-18[59-76], β-Asp65-PIP[59-67], D-Ala66-PNT.II, and D60,65E-PIP[59-67] displayed the most potent bactericidal activity against all tested pathogens in a dose-dependent manner (100-6.8 μg/ml), with a remarkable activity noted against S. aureus at 6.8 μg/ml dose within 6 h of incubation. Determination of minimum inhibitory concentrations (MICs) by a micro-broth dilution method at 100-3.125 μg/ml revealed that PIP-18[59-76], β-Asp65-PIP[59-67] and D-Ala66-PNT.II peptides exerted a potent inhibitory effect against S. aureus and B. pseudomallei (KHW) (MICs 3.125 μg/ml), while a much less inhibitory potency (MICs 12.5 μg/ml) was noted for β-Asp65-PIP[59-67] and D-Ala66-PNT.II peptides against B. pseudomallei (TES). Higher doses of peptides had no effect on the other two strains (i.e., Klebsiella pneumoniae and Streptococcus pneumoniae). Overall, PIP-18[59-76] possessed higher antimicrobial activity than that of chloramphenicol (CHL), ceftazidime (CF) and streptomycin (ST) (30 μg/disc). When the two most active peptides, PIP-18[59-76] and β-Asp65-PIP[59-67], were applied topically at a 150 mg/kg dose for testing wound healing activity in a mouse model of S. aureus infection, the former accelerates faster wound healing than the latter peptide at 14 days post-treatment. The western blot data suggest that the topical application of peptides (PIP-18[59-67] and β-Asp65-PIP[59-67]) modulates NF-kB mediated wound repair in mice with relatively little haemolytic (100-1.56 μg/ml) and cytotoxic (1000-3.125 μg/ml) effects evident on human cells in vitro.

Dimerization of matrix metalloproteinase-2 (MMP-2): functional implication in MMP-2 activation

Matrix metalloproteinase-2 (MMP-2) functions in diverse biological processes through the degradation of extracellular and non-extracellular matrix molecules. Because of its potential for tissue damage, there are several ways to regulate MMP-2 activity, including gene expression, compartmentalization, zymogen activation, and enzyme inactivation by extracellular inhibitors. Enzyme regulation through zymogen activation is important for the regulation of MMP-2 activity. In our previous studies, we showed that thrombin directly cleaved the propeptide of MMP-2 at specific sites for enzyme activation. We also demonstrated that heparan sulfate was required for thrombin-mediated activation of pro-MMP-2 by binding to thrombin, presumably through conformational changes at the active site of the enzyme. This suggests a regulatory mechanism for thrombin-mediated activation of pro-MMP-2. In this study, we found that MMP-2 formed a reduction-sensitive homodimer in a controlled manner and that Ca(2+) ion was essential for homodimerization of MMP-2. Homodimerization was not associated with protein kinase C-mediated phosphorylation of MMP-2. MMP-2 formed a homodimer through an intermolecular disulfide bond between Cys(102) and the neighboring Cys(102). Homodimerization of MMP-2 enhanced thrombin-mediated activation of pro-MMP-2. Moreover, the MMP-2 homodimer could cleave a small peptide substrate without removal of the propeptide. Taken together, our experimental data suggest a novel regulatory mechanism for pro-MMP-2 activation that is modulated through homodimerization of MMP-2.

Aspectos clínico-patológicos do envenenamento botrópico experimental em equinos

Estudou-se as alterações clínico-patológicas e laboratoriais em equinos, inoculados experimentalmente com a peçonha de Bothropoides jararaca, Bothrops jararacussu, Bothrops moojeni e Bothropoides neuwiedi, com a finalidade de fornecer subsídios para o diagnóstico do envenenamento pela picada dessas. Os venenos liofilizados foram diluídos em 1ml de solução fisiológica e administrados a seis equinos, por via subcutânea, nas doses de 0,5 e 1mg/kg (B. jararaca), 0,8 e 1,6mg/kg (B. jararacussu), 0,205mg/kg (B. moojeni) e 1mg/kg (B. neuwiedi). Todos os equinos, menos os que receberam o veneno de B. jararacussu, morreram Os sinais clínicos iniciaram-se entre 8min e 2h10min após a inoculação. O período de evolução variou, nos quatro casos de êxito letal, de 24h41min a 70h41min, e nos dois equinos que se recuperaram foi de 16 dias. O quadro clínico, independente do tipo de veneno e das doses, caracterizou-se por aumento de volume no local da inoculação, arrastar da pinça do membro inoculado no solo, inquietação, apatia, diminuição da resposta aos estímulos externos, mucosas pálidas e hemorragias. Os exames laboratoriais revelaram anemia normocítica normocrômica com progressiva diminuição no número de hemácias, da hemoglobina e do hematócrito, e leucocitose por neutrofilia. Houve aumento de alamina aminotransferase, creatinaquinase, dehidrogenase láctica, ureia e glicose, bem como aumento do tempo de ativação da protrombina e do tempo de tromboplastina parcial ativada. Os achados de necropsia foram extensas hemorragias no tecido subcutâneo, com presença de sangue não coagulado e em boa parte associadas a edema (edema hemorrágico), que se estendia desde o local da inoculação até as regiões cervical, torácica, escapular e membro. Na periferia das áreas hemorrágicas havia predominantemente edema gelatinoso. Havia ainda presença de grande quantidade de líquido sanguinolento nas cavidades torácica, pericárdica e abdominal. Não foram encontradas alterações histológicas significativas.

Rat skin wound healing induced by alternagin-C, a disintegrin-like, Cys-rich protein from Bothrops alternatus venom

Alternagin-C (ALT-C) is a disintegrin-like, Cys-rich protein isolated from Bothrops alternatus snake venom, which has been shown to induce in vivo angiogenesis. Therefore, this protein could be interesting as a new approach for tissue regeneration studies. Here the effects of ALT-C on fibroblasts and inflammatory cells, collagen type III and type I and TGF-α expression in a rat wounded skin model were studied. Thirty-five male Wistar rats (weight 270 ± 20 g) were divided into seven groups with five animals in each of the following groups: a control group which wounded animals received treatment with natrozol(®) gel only; ALT-C10, ALT-C60 and ALT-C100 groups of wounded animals that were treated with the same amount of gel containing 10, 60 and 100 ng of ALT-C, respectively. Animals were treated once a day with 20 µl of gel associated or not with ALT-C for 1, 3, 5 or 7 days. ALT-C treatment increased the fibroblast density, collagen deposition and accelerated the inflammatory process, mostly in the ALT-C60 group. These results indicate that ALT-C improves wound repair process in rat skin. Thus, ALT-C could be a candidate to the development of a novel therapeutic strategy for wounded skin repair.

Identification of novel proteins from the venom of a cryptic snake Drysdalia coronoides by a combined transcriptomics and proteomics approach

We have investigated the transcriptome and proteome of the venom of a cryptic Australian elapid snake Drysdalia coronoides. To probe into the transcriptome, we constructed a partial cDNA library from the venom gland of D. coronoides. The proteome of the venom of D. coronoides was explored by tryptic digestion of the crude venom followed by HPLC separation of the resulting peptides and MALDI-TOF/TOF mass spectrometric analysis. Importantly, the tandem MS data of the tryptic peptides of the venom not only confirmed the predicted protein sequences deduced from the transcriptome, but also added to our knowledge about the venom composition through identification of two more toxin families. Using both the approaches, we were able to identify proteins belonging to eight different snake venom protein superfamilies, namely, three-finger toxins, serine protease inhibitors, cysteine rich secretory proteins, phospholipases A(2), venom nerve growth factors, snake venom metalloproteases, vespryns, and a new family phospholipase B. We also identified three novel proteins belonging to the three-finger toxin superfamily.

A transcriptomic analysis of gene expression in the venom gland of the snake Bothrops alternatus (urutu)

Background

The genus Bothrops is widespread throughout Central and South America and is the principal cause of snakebite in these regions. Transcriptomic and proteomic studies have examined the venom composition of several species in this genus, but many others remain to be studied. In this work, we used a transcriptomic approach to examine the venom gland genes of Bothrops alternatus, a clinically important species found in southeastern and southern Brazil, Uruguay, northern Argentina and eastern Paraguay.

Results

A cDNA library of 5,350 expressed sequence tags (ESTs) was produced and assembled into 838 contigs and 4512 singletons. BLAST searches of relevant databases showed 30% hits and 70% no-hits, with toxin-related transcripts accounting for 23% and 78% of the total transcripts and hits, respectively. Gene ontology analysis identified non-toxin genes related to general metabolism, transcription and translation, processing and sorting, (polypeptide) degradation, structural functions and cell regulation. The major groups of toxin transcripts identified were metalloproteinases (81%), bradykinin-potentiating peptides/C-type natriuretic peptides (8.8%), phospholipases A₂ (5.6%), serine proteinases (1.9%) and C-type lectins (1.5%). Metalloproteinases were almost exclusively type PIII proteins, with few type PII and no type PI proteins. Phospholipases A₂ were essentially acidic; no basic PLA₂ were detected. Minor toxin transcripts were related to L-amino acid oxidase, cysteine-rich secretory proteins, dipeptidylpeptidase IV, hyaluronidase, three-finger toxins and ohanin. Two non-toxic proteins, thioredoxin and double-specificity phosphatase Dusp6, showed high sequence identity to similar proteins from other snakes. In addition to the above features, single-nucleotide polymorphisms, microsatellites, transposable elements and inverted repeats that could contribute to toxin diversity were observed.

Conclusions

Bothrops alternatus venom gland contains the major toxin classes described for other Bothrops venoms based on trancriptomic and proteomic studies. The predominance of type PIII metalloproteinases agrees with the well-known hemorrhagic activity of this venom, whereas the lower content of serine proteases and C-type lectins could contribute to less marked coagulopathy following envenoming by this species. The lack of basic PLA₂ agrees with the lower myotoxicity of this venom compared to other Bothrops species with these toxins. Together, these results contribute to our understanding of the physiopathology of envenoming by this species.

Envenenamento experimental por Bothropoides jararaca e Bothrops jararacussu em ovinos: aspectos clínico-patológicos e laboratoriais

Esse estudo teve como objetivo determinar as alterações clínico-patológicas e laboratoriais em ovinos inoculados com a peçonha de Bothropoides jararaca e Bothrops jararacussu, no intuito de fornecer subsídios que possam facilitar o estabelecimento do diagnóstico e do diagnóstico diferencial dessa condição. Os venenos liofilizados foram diluídos em 1 ml de solução fisiológica e administrados a quatro ovinos por via subcutânea. Três ovinos foram a óbito e um que recebeu a dose de 0,5mg/kg (B. jararaca), recuperou-se. Os sinais clínicos tiveram início entre 7 minutos e 1 hora. O período de evolução variou de 7 horas 9 minutos a 21 horas 59 minutos. O quadro clínico, independentemente das doses, caracterizou-se por aumento de volume no local da inoculação, tempo de sangramento e de preenchimento capilar aumentados, taquicardia, dispnéia, mucosas hipocoradas e apatia. Os exames laboratoriais revelaram acentuada anemia normocítica normocrômica, trombocitopenia, acentuada redução de fibrinogênio e proteínas plasmáticas totais, hematócrito diminuído em dois animais, além de acentuado aumento de creatinaquinase e desidrogenase lática em todos os animais. À necropsia, os principais achados no local da inoculação e tecidos adjacentes eram extensas hemorragias no animal que recebeu o veneno de B. jararaca e edema e acentuado edema pulmonar agudo para os dois animais envenenados por B. jararacussu. Além de hemorragia e edema a principal alteração histopatológica verificada foi necrose das fibras musculares e de vasos, no local de inoculação e adjacências. A necrose tubular renal foi atribuída ao quadro de choque. Nos ovinos deste estudo, o aumento de volume observado no local de inoculação e adjacências era constituído predominantemente por sangue (B. jararaca) e por edema (B. jararacussu).

Identification of a novel family of snake venom proteins Veficolins from Cerberus rynchops using a venom gland transcriptomics and proteomics approach

Cerberus rynchops (dog-faced water snake) belongs to Homalopsidae of Colubroidea (rear-fanged snakes). So far, venom compositions of snakes of the Homalopsidae family are not known. To determine the venom composition of C. rynchops, we have used both transcriptomics and proteomics approaches. The venom gland transcriptome revealed 104 ESTs and the presence of three known snake protein families, namely, metalloprotease, CRISP, and C-type lectin. In addition, we identified two proteins that showed sequence homology to ficolin, a mammalian protein with collagen-like and fibrinogen-like domains. We named them as ryncolin 1 and ryncolin 2 (rynchops ficolin) and this new family of snake venom proteins as veficolins (venom ficolins). On the basis of its structural similarity to ficolin, we speculate that ryncolins may induce platelet aggregation and/or initiate complement activation. To determine the proteome, the whole C. rynchops venom was trypsinized and fractionated by reverse phase HPLC followed by MALDI-MS/MS analysis of the tryptic peptides. Analysis of the tandem mass spectrometric data indicated the presence of all protein families compared to the translated cDNA library. Overall, our combined approach of transcriptomics and proteomics revealed that C. rynchops venom is among the least complex snake venom characterized to date despite the presence of a new family of snake venom proteins.

ADAM-17: the enzyme that does it all

This review focuses on the role of ADAM-17 in disease. Since its debut as the tumor necrosis factor converting enzyme (TACE), ADAM-17 has been reported to be an indispensible regulator of almost every cellular event from proliferation to migration. The central role of ADAM-17 in cell regulation is rooted in its diverse array of substrates: cytokines, growth factors, and their receptors as well as adhesion molecules are activated or inactivated by their cleavage with ADAM-17. It is therefore not surprising that ADAM-17 is implicated in numerous human diseases including cancer, heart disease, diabetes, rheumatoid arthritis, kidney fibrosis, Alzheimer's disease, and is a promising target for future treatments. The specific role of ADAM-17 in the pathophysiology of these diseases is very complex and depends on the cellular context. To exploit the therapeutic potential of ADAM-17, it is important to understand how its activity is regulated and how specific organs and cells can be targeted to inactivate or activate the enzyme.

Leberagin-C, A disintegrin-like/cysteine-rich protein from Macrovipera lebetina transmediterranea venom, inhibits alphavbeta3 integrin-mediated cell adhesion

Leberagin-C, a new member of the disintegrin-like/cysteine-rich (D/C) family, was purified to homogeneity from the venom of Tunisian snake Macrovipera lebetina transmediterranea. It is a monomeric protein with a molecular mass of 25,787 Da. Its complete sequence of 205 amino acid residues was established by cDNA cloning. The leberagin-C shows many conserved sequences with other known D/C proteins, like the SECD binding sites and a pattern of 28 cysteines. It is the first purified protein from M. lebetina transmediterranea with only two disintegrin-like/cysteine-rich domains. Leberagin-C is able to inhibit platelet aggregation induced by thrombin and arachidonic acid with IC(50) of 40 and 50 nM respectively. It was also able to inhibit the adhesion of melanoma tumour cells on fibrinogen and fibronectin, by interfering with the function of alphavbeta3 and, to a lesser extent, with alphavbeta6 and alpha5beta1 integrins. To our knowledge, leberagin-C is the sole described D/C protein that does not specifically interact with the alpha2beta1 integrin. Structure-activity relationship study of leberagin-C suggested that there are some important amino acid differences with jararhagin, the most studied PIII metalloprotease from Bothrops jararaca, notably around the SECD motif in its disintegrin-like domain. Other regions implicated in leberagin-C specificities could not be excluded.

Matrix metalloproteinases in inflammatory pathologies of the horse

The extracellular matrix (ECM) of connective tissue is constantly being remodelled to allow for growth and regeneration. Normal tissue maintenance requires the ECM components to be degraded and re-synthesised in relatively equal proportions. This degradation is facilitated by matrix metalloproteinases (MMPs) and their proteolytic action is controlled primarily by the tissue inhibitors of metalloproteinases (TIMPs). Both MMPs and TIMPs exist in a state of dynamic equilibrium, with a slight excess of one or the other depending on the need for either ECM breakdown or synthesis. Long-term disruption to this balance between MMPs and TIMPs will have pathological consequences. Matrix metalloproteinases are involved in a number of diseases in mammals, including the horse. Excess MMP activity can cause ECM destruction, as seen in the lamellar basement membrane in laminitis and the articular cartilage in osteoarthritis. Matrix metalloproteinase under-activity can potentially impede healing by preventing fibrinolysis in fibrotic conditions and the removal of scar tissue in wounds. Matrix metalloproteinases also degrade non-ECM proteins and regulate cell behaviour via the release of growth factors from the substrates they cleave, increasing the scope of their effects. This review looks at the involvement of MMPs in equine health and pathologies, whilst exploring the potential consequences of therapeutic intervention.

Aspectos clínico-patológicos e laboratoriais do envenenamento experimental por Bothrops alternatus em bovinos

Esse estudo teve como objetivo determinar as alterações clínico-patológicas e os achados laboratoriais em bovinos inoculados com a peçonha de Bothrops alternatus, no intuito de fornecer subsídios para o estabelecimento do diagnóstico e do diagnóstico diferencial, bem como esclarecer pontos obscuros da literatura pertinente. O veneno liofilizado foi diluído em 1 ml de solução fisiológica e administrado a cinco bovinos, por via subcutânea, nas doses de 0,0625, 0,125 e 0,25 mg/kg e a dois outros, por via intramuscular, nas doses de 0,25 e 0,45 mg/kg. Seis bovinos foram a óbito e um que recebeu a dose de 0,0625mg/kg, por via subcutânea, recuperou-se. Os sinais clínicos tiveram início entre 25 minutos a 5 horas 30 minutos após a inoculação. O período de evolução variou de 7 horas 18 minutos a 66 horas 12 minutos. Um animal recuperou-se após 92 horas. O quadro clínico, independentemente das doses, caracterizou-se por aumento de volume (hemorragia/hematoma) no local da inoculação, tempo de sangramento aumentado, mucosas hipocoradas e apatia. O exame laboratorial revelou progressiva anemia normocítica normocrômica, trombocitopenia, redução de fibrinogênio e proteínas plasmáticas totais, hematócrito e hemoglobina diminuídos, além de leve aumento dos níveis de creatinaquinase e desidrogenase lática. Á necropsia, havia, a partir do local da inoculação, extensos hematomas e áreas de hemorragia no tecido celular subcutâneo dos animais que receberam o veneno por via subcutânea; nos animais inoculados por via intramuscular, adicionalmente, havia hemorragia intramuscular. O endocárdio esquerdo apresentava extensas hemorragias e verificaram-se petéquias na serosa do rúmen e do omaso e na mucosa do abomaso e da vesícula biliar. Em cinco animais, o cólon, reto e região perirrenal estavam envoltos por coágulos de sangue. Ao exame histológico observou-se, além do quadro hemorragíparo, necrose muscular coagulativa, acompanhada de hemorragia, no entorno do local da inoculação nos animais que receberam o veneno por via intramuscular; essa lesão era discreta nos músculos próximos ao local de inoculação subcutânea. Nos bovinos deste estudo, o aumento de volume observado no local de inoculação e adjacências era constituído por sangue e não edema. Não foram observadas mioglobinúria, nem lesões macro ou microscópicas significativas nos rins. Este estudo indica que exemplares de B. alternatus, caso inoculem todo seu veneno, poderiam levar bovinos adultos à morte. Por outro lado, pelo fato de ofídios serem capazes de regular a quantidade de veneno inoculada e, possivelmente, não considerarem bovinos como presa potencial, é provável que o número de acidentes nessa espécie seja pequeno, o que está de acordo com o observado na maioria dos centros diagnóstico anátomo-patológico no país.

Insights into and speculations about snake venom metalloproteinase (SVMP) synthesis, folding and disulfide bond formation and their contribution to venom complexity

As more data are generated from proteome and transcriptome analyses of snake venoms, we are gaining an appreciation of the complexity of the venoms and, to some degree, the various sources of such complexity. However, our knowledge is still far from complete. The translation of genetic information from the snake genome to the transcriptome and ultimately the proteome is only beginning to be appreciated, and will require significantly more investigation of the snake venom genomic structure prior to a complete understanding of the genesis of venom composition. Venom complexity, however, is derived not only from the venom genomic structure but also from transcriptome generation and translation and, perhaps most importantly, post-translation modification of the nascent venom proteome. In this review, we examine the snake venom metalloproteinases, some of the predominant components in viperid venoms, with regard to possible synthesis and post-translational mechanisms that contribute to venom complexity. The aim of this review is to highlight the state of our knowledge on snake venom metalloproteinase post-translational processing and to suggest testable hypotheses regarding the cellular mechanisms associated with snake venom metalloproteinase complexity in venoms.

Molecular and functional characterization of a new non-hemorrhagic metalloprotease from Bothrops jararacussu snake venom with antiplatelet activity

BjussuMP-II is an acidic low molecular weight metalloprotease (Mr approximately 24,000 and pI approximately 6.5), isolated from Bothrops jararacussu snake venom. The chromatographic profile in RP-HPLC and its N-terminal sequence confirmed its high purity level. Its complete cDNA was obtained by RT-PCR and the 615bp codified for a mature protein of 205 amino acid residues. The multiple alignment of its deduced amino acid sequence and those of other snake venom metalloproteases showed a high structural similarity, mainly among class P-I proteases. The molecular modeling analysis of BjussuMP-II showed also conserved structural features with other SVMPs. BjussuMP-II did not induce hemorrhage, myotoxicity and lethality, but displayed dose-dependent proteolytic activity on fibrinogen, collagen, fibrin, casein and gelatin, keeping stable at different pHs, temperatures and presence of several divalent ions. BjussuMP-II did not show any clotting or anticoagulant activity on human citrated plasma, in contrast to its inhibitory effects on platelet aggregation. The aspects broached, in this work, provide data on the relationship between structure and function, in order to better understand the effects elicited by snake venom metalloproteases.

Cytoskeletal rearrangement and cell death induced by Bothrops alternatus snake venom in cultured Madin–Darby canine kidney cells

Bothrops snake venoms cause renal damage, with renal failure being the main cause of death in humans bitten by these snakes. In this work, we investigated the cytoskeletal rearrangement and cytotoxicity caused by Bothrops alternatus venom in cultured Madin–Darby canine kidney (MDCK) cells. Incubation with venom (10 and 100 µg/mL) significantly (p <0.05) decreased the cellular uptake of neutral red dye after 1 and 3 h. Venom (100 µg/mL) also markedly decreased the transepithelial electrical resistance (RT) across MDCK monolayers. Staining with rhodamine-conjugated phalloidin revealed disarray of the cytoskeleton that involved the stress fibers at the basal cell surface and focal adhesion-associated F-actin in the cell–matrix contact region. Feulgen staining showed a significant decrease in the number of cells undergoing mitosis and an increase in the frequency of altered nuclei. Scanning electron microscopy revealed a decrease in the number of microvilli and the presence of cells with a fusiform format. Flow cytometry with annexin V and propidium iodide showed that cell death occurred by necrosis, with little apoptosis, a conclusion supported by the lack of DNA fragmentation characteristic of apoptosis. Pretreating the cells with catalase significantly attenuated the venom-induced loss of viability, indicating a possible involvement of H2O2 in the cellular damage; less protection was observed with superoxide dismutase or Nω-nitro-l-arginine methyl ester. These results indicate that Bothrops alternatus venom is cytotoxic to cultured MDCK cells, possibly via the action of reactive oxygen species. This cytotoxicity could contribute to nephrotoxicity after envenoming by this species.

Use of SILAC for exploring sheddase and matrix degradation of fibroblasts in culture by the PIII SVMP atrolysin A: Identification of two novel substrates with functional relevance

Snake venom metalloproteinases (SVMPs) in Viperid venoms primarily function to give rise to local and systemic hemorrhage following snake envenomation. Years of research on these toxins, both in vitro and in vivo, indicate that they function by disrupting capillary basement membranes, stromal matrix and cell-cell and cell-matrix contacts to allow escape of capillary contents under pressure. However, most of these studies used either defined substrates in vitro or were limited by relevant antibodies for detection of sites of action in vivo. In this investigation we use stable isotope-labeled amino acids in culture (SILAC) to determine novel proteolytic activities for exogenously added atrolysin A, a hemorrhagic PIII SVMP isolated from Crotalus atrox venom. When comparing the solubilized products of SILAC-labeled cultured human fibroblasts treated with atrolysin A to that of untreated fibroblasts using LC/MS/MS, several proteins were identified as being released into the culture media specifically due to atrolysin A proteolytic activity. These included collagen VI, fibronectin, fibulin 2 and annexin V. Of particular interest was the observation of collagen VI and annexin V in that the release of these substrates could play a role in altering hemostasis and promote hemorrhage caused by the more typical actions of atrolysin A. In summary, this study demonstrates the utility of SILAC for exploring sheddase activity with cells in culture and suggests the presence of two novel substrates for SVMPs that may play a pathological role in altering host hemostasis during envenomation.

Cytotoxic, thrombolytic and edematogenic activities of leucurolysin-a, a metalloproteinase from Bothrops leucurus snake venom

Leucurolysin-a (leuc-a), a 23 kDa non-hemorrhagic metalloproteinase, is found in venom of the viper Bothrops leucurus. Here, we examine the biological consequences of leuc-a, including thrombolytic activity, direct effects on endothelial cells in culture and edematogenic activity in vivo. We demonstrate fibrinolytic activity of leuc-a, in which the protease specifically degrades alpha, beta, and gamma-gamma chains. While not causing hemorrhaging, leuc-a does cause thrombolytic activities in whole blood clots. Endothelial cells are highly resistant to leuc-a in culture. Cell viability suffered only when cells were exposed to large quantities of the protease. Nevertheless, leuc-a induces changes in cell morphology. The impact of leuc-a on cell adhesion was confirmed by an adhesion assay, in which cell adhesion to fibronectin decreased due to leuc-a. This mild cellular impact is unlike that of crude venom, where lower concentrations triggered cell death and a greater reduction in cell adhesion. Also, leuc-a increased microvessel permeability with marked edema in mice peritoneum and foot pads. These effects are similar to those of other P-I class SVPMs. These in vivo effects were weaker when crude venom was tested. In conclusion, albeit not showing significant hemorrhagic activity, leuc-a can induce a prominent edema which appears to be significant in the local effects observed after B. leucurus venom accidents.

Molecular characterization and phylogenetic analysis of BjussuMP-I: A RGD-P-III class hemorrhagic metalloprotease from Bothrops jararacussu snake venom

Snake venom metalloproteases (SVMPs) embody zinc-dependent multidomain enzymes responsible for a relevant pathophysiology in envenomation, including local and systemic hemorrhage. The molecular features responsible for hemorrhagic potency of SVMPs have been associated with their multidomains structures which can target these proteins them to several receptors of different tissues and cellular types. BjussuMP-I, a SVMP isolated from the Bothrops jararacussu venom, has been characterized as a P-III hemorrhagic metalloprotease. The complete cDNA sequence of BjussuMP-I with 1641bp encodes open reading frames of 547 amino acid residues, which conserve the common domains of P-III high molecular weight hemorrhagic metalloproteases: (i) pre-pro-peptide, (ii) metalloprotease, (iii) disintegrin-like and (iv) rich cysteine domain. BjussuMP-I induced lyses in fibrin clots and inhibited collagen- and ADP-induced platelet aggregation. We are reporting, for the first time, the primary structure of an RGD-P-III class snake venom metalloprotease. A phylogenetic analysis of the BjussuMP-I metalloprotease/catalytic domain was performed to get new insights into the molecular evolution of the metalloproteases. A theoretical molecular model of this domain was built through folding recognition (threading) techniques and refined by molecular dynamics simulation. Then, the final BjussuMP-I catalytic domain model was compared to other SVMPs and Reprolysin family proteins in order to identify eventual structural differences, which could help to understand the biochemical activities of these enzymes. The presence of large hydrophobic areas and some conserved surface charge-positive residues were identified as important features of the SVMPs and other metalloproteases.

Snake venom metalloproteases--structure and function of catalytic and disintegrin domains

Snake venoms are relevant sources of toxins that have evolved towards the engineering of highly active compounds. In the last years, research efforts have produced great advance in their understanding and uses. Metalloproteases with disintegrin domains are among the most abundant toxins in many Viperidae snake venoms. This review will focus on the structure, function and possible applications of the metalloprotease and disintegrin domains.

Tick saliva is a potent inhibitor of endothelial cell proliferation and angiogenesis

We report for the first time that saliva of the hard tick and Lyme disease vector, Ixodes scapularis, is a potent inhibitor of angiogenesis. Saliva (< or = 1:500 dilutions) or salivary gland (0.1-0.5 pairs/assay) dose-dependently inhibits microvascular endothelial cell (MVEC) proliferation. Inhibition was also detected with the saliva of the cattle tick Boophilus microplus but not with the salivary gland of Anopheles gambiae, An. stephensi, Lutzomyia longipalpis, Phlebotomus papatasi, Aedes aegypti, Culex quinquefasciatus, and Cimex lectularius. Inhibition of MVEC proliferation by I. Scapularis saliva was accompanied by a change in cell shape (shrinkage of the cytoplasm with loss of cell-cell interactions) and apoptosis which was estimated by expression of phosphatidylserine using the Apopercentage dye, and by a typical pattern of chromatin margination, condensation, and fragmentation as revealed by nuclear staining with Hoechst 33258. The effect of saliva appears to be mediated by endothelial cell alpha5beta1 integrin, because monoclonal antibodies against this but not alphavbeta3, alphavbeta5, alpha9beta1, or alpha2beta1 integrins remarkably block its effect. In addition, SDS/PAGE shows that saliva specifically degrades purified alpha5beta1 but not alphavbeta5 or alphavbeta3 integrins. Incubation of saliva with EDTA and 1,10-phenanthroline, but not phenylmethylsulfonyl fluoride (PMSF), inhibits saliva-dependent degradation of purified alpha5beta1 integrin, suggesting that a metalloprotease is responsible for the activity. Finally, saliva at < or = 1:1,000 dilutions blocks sprouting formation from chick embryo aorta implanted in Matrigel, an in vitro model of angiogenesis. These findings introduce the concept that tick saliva is a negative modulator of angiogenesis-dependent wound healing and tissue repair, therefore allowing ticks to feed for days. Inhibition of angiogenesis was hitherto an unidentified biologic property of the saliva of any blood-sucking arthropod studied so far. Its presence in tick saliva may be regarded as an additional source of angiogenesis inhibitors with potential applications for the study of both vector and vascular biology.

Alternagin-C, a disintegrin-like protein from the venom of Bothrops alternatus, modulates alpha2beta1 integrin-mediated cell adhesion, migration and proliferation

The alpha2beta1 integrin is a major collagen receptor that plays an essential role in the adhesion of normal and tumor cells to the extracellular matrix. Alternagin-C (ALT-C), a disintegrin-like protein purified from the venom of the Brazilian snake Bothrops alternatus, competitively interacts with the alpha2beta1 integrin, thereby inhibiting collagen binding. When immobilized in plate wells, ALT-C supports the adhesion of fibroblasts as well as of human vein endothelial cells (HUVEC) and does not detach cells previously bound to collagen I. ALT-C is a strong inducer of HUVEC proliferation in vitro. Gene expression analysis was done using an Affimetrix HU-95A probe array with probe sets of approximately 10,000 human genes. In human fibroblasts growing on collagen-coated plates, ALT-C up-regulates the expression of several growth factors including vascular endothelial growth factor, as well as some cell cycle control genes. Up-regulation of the vascular endothelial growth factor gene and other growth factors could explain the positive effect on HUVEC proliferation. ALT-C also strongly activates protein kinase B phosphorylation, a signaling event involved in endothelial cell survival and angiogenesis. In human neutrophils, ALT-C has a potent chemotactic effect modulated by the intracellular signaling cascade characteristic of integrin-activated pathways. Thus, ALT-C acts as a survival factor, promoting adhesion, migration and endothelial cell proliferation after binding to alpha2beta1 integrin on the cell surface. The biological activities of ALT-C may be helpful as a therapeutic strategy in tissue regeneration as well as in the design of new therapeutic agents targeting alpha2beta1 integrin.

Platelets as targets of snake venom metalloproteinases

For centuries snake venoms have been known to interfere with haemostasis and this is now known basically due either to toxins activating/inhibiting clotting factors, having effects on blood vessels or interfering with platelet function. In this short review, the interaction of one major group of toxins, the snake venom metalloproteinases, with platelets is considered. This is relevant for understanding the mechanism of haemorrhage induced by these toxins.

Snake venom probes of platelet adhesion receptors and their ligands

Snake venom proteins that modulate platelet adhesive interactions are chiefly from either of two main structural families: the C-type lectin-like family, or the metalloproteinase-disintegrins. Snake venom probes from both families selectively target platelet adhesion receptors, including glycoprotein (GP) Ib-IX-V, GP VI, alpha2beta1 and alphaIIbbeta3 (GP IIb-IIIa). These receptors act together to mediate platelet adhesion, activation and aggregation (thrombus formation) under hydrodynamic shear stress in flowing blood. The receptors are members of the leucine-rich repeat family (GP Ib-IX-V), the immunoglobulin superfamily (GP VI), or integrins (alpha2beta1, alphaIIbbeta3). In addition, adhesive glycoproteins in matrix and/or plasma such as von Willebrand factor (that binds GP Ibalpha and alphaIIbbeta3), collagen (that binds GP V, GP VI and alpha2beta1), or fibrinogen (that binds alphaIIbbeta3), are also targeted by C-type lectin family or metalloproteinase-disintegrin snake venom proteins. Emerging structural and functional evidence is beginning to explain how interactions between the conserved structural module-domains that make up these mammalian and snake proteins are regulated. Whether homologous adhesion/counter-receptors on platelets and other vascular cells are also potential snake venom targets is as yet largely unexplored.

Jararhagin, a snake venom metalloproteinase-disintegrin, stimulates epithelial cell migration in an in vitro restitution model

The snake venom metalloproteinase-disintegrin jararhagin (JG) has no chemotactic activity but stimulates the migration of neutrophils in vivo through a mechanism still unclear. In this study we investigated the effects of jararhagin on epithelial cell adhesion and migration in vitro. F-actin arrangement and the distribution of laminin, fibronectin, several integrins and phosphorylated Focal Adhesion Kinase (FAK) were studied using rhodamine-phalloidin and immunofluorescence. Maximum stimulation of migration (about 100%) was obtained with 5 microg/ml JG, with about 38% inhibition of cellular adhesion. In migratory cells the toxin stimulated the formation of filopodia, lamellipodia and stress fibers. The pericellular fibronectin matrix was lost in migrating cells, while laminin was less affected. The toxin stimulated FAK phosphorylation and the recruitment of alphav-containing integrins to focal contacts, whereas integrins containing the alpha2 subunit were reduced in these junctions. Inactivation of the toxin with 1,10 phenanthroline showed that the catalytic activity is important for the effect of jararhagin on cell migration, FAK phosphorylation and for the recruitment of alphav, but not as much for the anti-adhesive effect. In conclusion, jararhagin stimulates the migration of epithelial cells in vitro through a mechanism that involves its proteolytic activity, qualitative changes in cellular adhesion and the formation of actin-rich cellular processes.

Alternagin-C, a Disintegrin-like Protein, Induces Vascular Endothelial Cell Growth Factor (VEGF) Expression and Endothelial Cell Proliferation in Vitro

Alternagin-C (ALT-C), a disintegrin-like protein purified from the venom of the Brazilian snake Bothrops alternatus, interacts with the major collagen I receptor, the alpha(2)beta(1) integrin, inhibiting collagen binding. Here we show that ALT-C also inhibits the adhesion of a mouse fibroblast cell line (NIH-3T3) to collagen I (IC(50) 2.2 microm). In addition, when immobilized on plate wells, ALT-C supports the adhesion of this cell line as well as of human vein endothelial cell (HUVEC). ALT-C (3 microm) does not detach cells that were previously bound to collagen I. ALT-C (5 nm) induces HUVEC proliferation in vitro, and it inhibits the positive effect of vascular endothelial growth factor (VEGF) or FGF-2 on the proliferation of these cells, thus suggesting a common mechanism for these proteins. Gene expression analysis of human fibroblasts growing on ALT-C- or collagen-coated plates showed that ALT-C and collagen I induce a very similar pattern of gene expression. When compared with cells growing on plastic only, ALT-C up-regulates the expression of 45 genes including the VEGF gene and down-regulates the expression of 30 genes. Fibroblast VEGF expression was confirmed by RT-PCR and ELISA assay. Up-regulation of the VEGF gene and other growth factors could explain the positive effect on HUVEC proliferation. ALT-C also strongly activates Akt/PKB phosphorylation, a signaling event involved in endothelial survival and angiogenesis. In conclusion, ALT-C acts as a survival factor, promoting adhesion and endothelial cell proliferation.