A proteomic analysis of Pakistan Daboia russelii russelii venom and assessment of potency of Indian polyvalent and monovalent antivenom

To address the dearth of knowledge on the biochemical composition of Pakistan Russell's Viper (Daboia russelii russelii) venom (RVV), the venom proteome has been analyzed and several biochemical and pharmacological properties of the venom were investigated. SDS-PAGE (reduced) analysis indicated that proteins/peptides in the molecular mass range of ~56.0-105.0kDa, 31.6-51.0kDa, 15.6-30.0kDa, 9.0-14.2kDa and 5.6-7.2kDa contribute approximately 9.8%, 12.1%, 13.4%, 34.1% and 30.5%, respectively of Pakistan RVV. Proteomics analysis of gel-filtration peaks of RVV resulted in identification of 75 proteins/peptides which belong to 14 distinct snake venom protein families. Phospholipases A2 (32.8%), Kunitz type serine protease inhibitors (28.4%), and snake venom metalloproteases (21.8%) comprised the majority of Pakistan RVV proteins, while 11 additional families accounted for 6.5-0.2%. Occurrence of aminotransferase, endo-β-glycosidase, and disintegrins is reported for the first time in RVV. Several of RVV proteins/peptides share significant sequence homology across Viperidae subfamilies. Pakistan RVV was well recognized by both the polyvalent (PAV) and monovalent (MAV) antivenom manufactured in India; nonetheless, immunological cross-reactivity determined by ELISA and neutralization of pro-coagulant/anticoagulant activity of RVV and its fractions by MAV surpassed that of PAV.

BIOLOGICAL SIGNIFICANCE

The study establishes the proteome profile of the Pakistan RVV, thereby indicating the presence of diverse proteins and peptides that play a significant role in the pathophysiology of RVV bite. Further, the proteomic findings will contribute to understand the variation in venom composition owing to different geographical location and identification of pharmacologically important proteins in Pakistan RVV.

Genetic polymorphisms and asthma: findings from a case-control study in the Madeira island population

BACKGROUND

Asthma is a complex disease influenced by multiple genetic and environmental factors. While Madeira has the highest prevalence of asthma in Portugal (14.6%), the effect of both genetic and environmental factors in this population has never been assessed. We categorized 98 asthma patients according to the Global Initiative for Asthma (GINA) guidelines, established their sensitization profile, and measured their forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) indexes. Selected single nucleotide polymorphisms (SNPs) were analysed as potential markers for asthma susceptibility and severity in the interleukin 4 (IL4), interleukin 13 (IL13), beta-2-adrenergic receptor (ADRB2), a disintegrin and metalloprotease 33 (ADAM33), gasdermin-like (GSDML) and the signal transducer and activator of transcription 6 (STAT6) genes comparatively to a population reference set.

RESULTS

Although mites are the major source of allergic sensitization, no significant difference was found amongst asthma severity categories. IL4-590*CT/TT and IL4-RP2*253183/183183 were found to predict the risk (2-fold) and severity (3 to 4-fold) of asthma and were associated with a lower FEV1 index. ADRB2-c.16*AG is a risk factor (3.5-fold), while genotype GSDML-236*TT was protective (4-fold) for moderate-severe asthma. ADAM33-V4*C was associated to asthma and mild asthma by the transmission disequilibrium test (TDT). Finally, ADAM33-V4*CC and STAT6-21*TT were associated with higher sensitization (mean wheal size ≥10 mm) to house dust (1.4-fold) and storage mite (7.8-fold).

CONCLUSION

In Madeira, IL4-590C/T, IL4-RP2 253/183, GSDML-236C/T and ADAM33-V4C/G SNPs are important risk factors for asthma susceptibility and severity, with implications for asthma healthcare management.

Disintegrin, hemorrhagic, and proteolytic activities of Mohave rattlesnake, Crotalus scutulatus scutulatus venoms lacking Mojave toxin

Venom from the Mohave rattlesnake, Crotalus scutulatus scutulatus, has been reported to be either: (1) neurotoxic; (2) hemorrhagic, or both (3) neurotoxic and hemorrhagic. In this study, 14 Mohave rattlesnakes from Arizona and Texas (USA) were analyzed for the presence of disintegrins and Mojave toxin. All venom samples were analyzed for the presence of hemorrhagic, proteolytic and disintegrin activities. The venoms were each chromatographed by reverse phase and their fractions tested for disintegrin activity. All specimens containing Mojave toxin were the most toxic and lacked proteolytic, hemorrhagic and disintegrin activities. In contrast, the venoms containing these activities lacked Mojave toxin. Two disintegrin genes, scutustatin and mojavestatin, were identified by PCR of genomic sequences. Scutustatin is a highly conserved disintegrin, while mojavestatin shows low conservation to other known disintegrins. Venoms with the highest LD50 measurements lacked both disintegrin genes, while the specimens with intermediate and low LD50 contained both genes. The intermediate LD50 group contained Mojave toxin and both disintegrin genes, but lacked hemorrhagic and disintegrin activity. Our results raise the possibility that scutustatin and mojavestatin are not expressed in the intermediate LD50 group, or that they may not be the same disintegrins responsible for the disintegrin activity found in the venom. Therefore, it is possible that Mohave rattlesnakes may produce more than two disintegrins.

The disintegrin-metalloproteinases ADAM9, ADAM12, and ADAM15 are upregulated in gastric cancer

The ADAMs (A disintegrin and metalloproteinase) are a family of cell-surface membrane glycoproteins, whose multidomain structure enables diverse roles in a wide range of cellular processes. Accumulating evidence associates an increased expression of individual ADAM family members with various types of cancer, and we investigated the possible involvement of ADAM9, 12 and 15 in the pathogenesis of gastric cancer (GC). Using immunohistochemistry and quantitative RT-PCR, we examined the transcription and expression pattern of ADAM9, 12, and 15 in GCs and the corresponding non-tumor tissue, and in GC cell lines (AGS, MKN45, MKN28, NCI-N87, KATOIII). All three ADAMs were found to be significantly upregulated in GC compared to non-neoplastic foveolar epithelium, with ADAM12 expression being higher in intestinal- than in diffuse-type tumors. In vitro proliferation assays were used to evaluate the effects of ADAM-specific antibodies on the growth of GC cell lines. The administration of anti-ADAM9 and anti-ADAM15 antibodies inhibited cell growth, whereas anti-ADAM12 enhanced the proliferation of the GC cell lines. ADAM9, 12 and 15 are implicated in the malignant growth of GC cells, perhaps via the interaction with adhesion molecules, or the proteolytic 'shedding' of signaling molecules and the consequent transactivation of their receptors, such as the epithelial growth factor receptor and its ligands. The resultant modulation of the tumor-host interface may contribute to the pathogenesis, development or progression of gastric cancer.

Increased expression of ADAM family members in human breast cancer and breast cancer cell lines

PURPOSE

ADAMs (A Disintegrin and Metalloprotease) are multifunctional, membrane-bound cell surface glycoproteins, which have numerous functions in cell growth, differentiation, and motility. We wished to investigate the expression of ADAM 9, 10, 12, 15, and in human breast cancer.

METHODS

Expression of ADAMs was determined in breast cancer specimens and the corresponding non-neoplastic breast tissue from 24 patients, and in the MCF-7 and MDA-MB 453 breast cancer cell lines via quantitative RT-PCR and immunohistochemistry. The effects of anti-ADAM antibodies on cell proliferation were assessed by measuring DNA-synthesis.

RESULTS

Breast cancer tissue samples showed increased mRNA expression of ADAM 9, 12, and 17, whereas ADAM 10 and 15 were not differently expressed. Protein expression was studied by immunohistochemistry. All ADAMs were expressed in MCF-7 and MDA-MB453 cell lines, with the highest expression levels being observed for ADAM 9, 12, and 17. Application of anti-ADAM 15 and anti-ADAM 17 antibodies significantly inhibited the proliferation of both MCF-7 and MDA-MB453 breast cancer cell lines. In contrast, the growth of MCF-7 cells appeared to be stimulated by the administration of anti-ADAM 12 antibody.

CONCLUSION

The results of this study suggest that ADAMs are differentially expressed in human breast cancer and are capable of modulating tumour cell growth.

Cloning, expression, and characterization of a bi-functional disintegrin/alkaline phosphatase hybrid protein

Integrins are transmembrane heterodimeric glycoproteins responsible for cellular communication; therefore, they play an essential role in many physiological events. Viper snake venoms contain integrin antagonists called disintegrins which bind and inhibit integrin function. They present a loop containing an RGD motif responsible for integrin binding. The engineering of disintegrins fused to a reporter enzyme will be an interesting approach to build integrin markers. Even more, the disintegrin scaffold could be used to present other protein binding motifs. In this work, we have obtained alkaline phosphatase (APv) tagged eristostatin (Er) by cloning and expressing eristostatin DNA into the pLIP6-GN vector. Eristostatin, a 49 residue disintegrin, binds selectively to alphaIIbbeta3 integrin, inhibiting its binding to fibrinogen. The resulting fusion protein Er/APv was identified by SDS-PAGE and by Western blotting using both anti-Er and anti-AP antibodies. This fusion protein showed enzymatic AP activity similar to that of wild APv and its potential use for an alphaIIbbeta3 integrin assay was tested in a one-step dot blot using immobilized cells incubated with the marker and developed by AP substrate. Er/APv showed selectivity towards platelets and alphaIIbbeta3 integrin transfected cells and reacted with the same region as unlabeled Er, as analyzed in competition assays. Our data present a novel tool, Er/APv, with potential use as molecular marker in processes where the alphaIIbbeta3 integrin is involved.

Increased expression of a novel osteoclast-stimulating factor, ADAM8, in interface tissue around loosened hip prostheses

OBJECTIVE

ADAM8 is a protein of a disintegrin and a metalloproteinase family that can induce osteoclast fusion and activity, perhaps via interactions involving integrin receptors and their cysteine-rich/disintegrin domains. Because loosening of hip replacement implants is characterized by foreign body giant cells and peri-implant osteoclasts, it was speculated that this molecule might be (over)expressed in the synovial membrane-like interface tissues.

METHODS

In situ hybridization; immunohistochemical staining with or without tartrate-resistant acid phosphatase (TRAP) staining; image analysis/morphometry; isolation, amplification, and cloning of ADAM8; nucleotide sequencing; quantitative reverse transcriptase-polymerase chain reaction (RT-PCR); and Western blot.

RESULTS

In situ hybridization disclosed ADAM8 mRNA in mono- and multinuclear cells in both interface and control synovial samples. Quantitative RT-PCR revealed high ADAM8 mRNA copy numbers in interface tissue (p < 0.01). Accordingly, extensive ADAM8 immunoreactivity was observed in the lining-like layers and sublining areas of interface tissue (p < 0.001). A 65 kDa ADAM8 band in Western blot of tissue extracts confirmed these findings. ADAM8/TRAP double staining showed close spatial relationships of ADAM8 positive precursor cells with other precursors and/or TRAP-positive multinuclear cells.

CONCLUSION

ADAM8 is (over)expressed in tissues around aseptically loosened total hip implants, which are characterized by chronic foreign body inflammation and peri-implant bone loss. This is compatible with a role for ADAM8 in the formation of foreign body giant cells and osteoclasts.

Localization of ADAM10 and Notch receptors in bone

In Drosophila melanogaster, the role of the metallodisintegrin, Kuzbanian (kuz), is thought to involve activation of the Drosophila Notch receptor that plays a role in cell-fate determination during neurogenesis and myoblast differentiation. To understand the possible function(s) of a-disintegrin and metalloproteinase (ADAM10), the mammalian ortholog of kuz, in the skeleton, we studied its expression as well as the messenger RNA (mRNA) encoding one candidate substrate, the mammalian Notch2 receptor in bone, bone cells, and cartilage. In sections of neonatal rat tibiae, ADAM10 is expressed in specific regions of articular cartilage and metaphyseal bone. Expression of ADAM10 in articular cartilage occurs predominantly in superficial chondrocytes and becomes more sporadic with increasing distance from the articular surface. In bone, ADAM10 is expressed by periosteal cells, osteoblasts, and osteocytes at locations of active bone formation. Osteoclasts did not express ADAM10. Notch2 mRNA expression was not detectable in superficial chondrocytes. However it colocalized at all sites of ADAM10 expression in bone cells. In vitro, both primary human osteoblasts and osteoblast cell lines expressed a single 4.5 kb and 7.5 kb transcript of ADAM10 and the Notch2 receptor homolog, respectively. Subcellular localization of the ADAM10 protein in MG-63 cells was determined using immunofluorescent techniques. These observations showed clearly that the ADAM10 protein was expressed in the trans-Golgi network and on the plasma membrane. Western blot analysis of fractionated cells showed that, in the plasma membrane fraction, the previously characterized 58 kDa and 56 kDa isoforms were present, whereas, in the trans-Golgi network, the ADAM10 protein was present in several additional bands, possibly indicative of further interdomain processing of the ADAM10 protein. The metallodisintegrins (ADAMs) have several putative functions, including modulation of cell adhesion, membrane-associated proteolysis, and cell-cell signaling. These observations suggest that, in bone but not cartilage, ADAM10 has catalytic activity within the transGolgi network and may play a role in the activation of Notch receptor homologs. This implicates ADAM10 in cell-fate determination of osteoblast progenitor cells, possibly during skeletal development and normal bone remodeling. Plasma-membrane-associated ADAM10 may confer alternative functions.

Voltage-dependent activation of frog eggs by a sperm surface disintegrin peptide

Fertilin, a sperm protein of the metalloprotease/disintegrin/cysteine-rich (MDC) family, plays a critical role in sperm-egg binding in mammals. Peptides corresponding to the disintegrin domain of fertilin and antibodies against fertilin have been shown to inhibit mammalian sperm-egg binding and fusion. A protein from the same family, xMDC16, was recently cloned from frog (Xenopus laevis) testis and was found to be involved in frog sperm-egg binding. Here we report that xMDC16 is localized predominantly on the posterior surface of egg jelly-activated sperm, and peptides from the disintegrin domain of this protein activate eggs when applied near the egg surface. Egg activation was dependent on (1) specific amino acid residues (KTX); (2) the presence of divalent cations, but not external Ca2+ alone; and (3) voltage across the egg plasma membrane. This is the first demonstration of egg activation in vertebrates by the surface application of a peptide derived from a sperm surface protein, supporting a model for egg activation that involves a signal transducing receptor for sperm in the egg's plasma membrane.