Cell Surface Proteins (cell + surface_protein)

Distribution by Scientific Domains


Selected Abstracts


Fibrodysplasia Ossificans Progressiva (FOP), a Disorder of Ectopic Osteogenesis, Misregulates Cell Surface Expression and Trafficking of BMPRIA,,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 7 2005
Lourdes Serrano de la Peña
Abstract FOP is a disorder in which skeletal muscle is progressively replaced with bone. FOP lymphocytes, a model system for exploring the BMP pathway in these patients, exhibit a defect in BMPRIA internalization and increased activation of downstream signaling, suggesting that altered BMP receptor trafficking underlies ectopic bone formation in this disease. Introduction: Fibrodysplasia ossificans progressiva (FOP) is a severely disabling disorder characterized by progressive heterotopic ossification of connective tissues. Whereas the genetic defect and pathophysiology of this condition remain enigmatic, BMP4 mRNA and protein are overexpressed, and mRNAs for a subset of secreted BMP antagonists are not synthesized at appropriate levels in cultured lymphocytes from FOP patients. These data suggest involvement of altered BMP signaling in the disease. In this study, we investigate whether the abnormality is associated with defective BMP receptor function in lymphocytes. Materials and Methods: Cell surface proteins were quantified by fluorescence-activated cell sorting (FACS). Protein phosphorylation was assayed by immunoprecipitation and immunoblotting. Protein synthesis and degradation were examined by [35S]methionine labeling and pulse-chase assays. mRNA was detected by RT-PCR. Results: FOP lymphocytes expressed 6-fold higher levels of BMP receptor type IA (BMPRIA) on the cell surface compared with control cells and displayed a marked reduction in ligand-stimulated internalization and degradation of BMPRIA. Moreover, in control cells, BMP4 treatment increased BMPRIA phosphorylation, whereas BMPRIA showed ligand-insensitive constitutive phosphorylation in FOP cells. Our data additionally support that the p38 mitogen-activated protein kinase (MAPK) signaling pathway is a major BMP signaling pathway in these cell lines and that expression of inhibitor of DNA binding and differentiation 1 (ID-1), a transcriptional target of BMP signaling, is enhanced in FOP cells. Conclusions: These data extend our previous observations of misregulated BMP4 signaling in FOP lymphocytes and show that cell surface overabundance and constitutive phosphorylation of BMPRIA are associated with a defect in receptor internalization. Altered BMP receptor trafficking may play a significant role in FOP pathogenesis. [source]


A putative lipoprotein of Sphingomonas sp. strain A1 binds alginate rather than a lipid moiety

FEMS MICROBIOLOGY LETTERS, Issue 2 2008
Jinshan He
Abstract Gram-negative Sphingomonas sp. strain A1 accumulates alginate in the cell surface pit and directly incorporates the polysaccharide into its cytoplasm through a ,superchannel'. A cell surface protein Algp7 (27 kDa) is inducibly expressed in the presence of alginate. Although the protein Algp7 was initially classified as a lipoprotein based on its primary structure, Algp7 purified from strain A1 cells did not possess a lipid moiety. Algp7 bound alginate efficiently at a neutral pH with a Kd of 3.6 × 10,8 M, suggesting that the cell surface protein contributed to accumulation of alginate in the pit. [source]


Mss11p is a transcription factor regulating pseudohyphal differentiation, invasive growth and starch metabolism in Saccharomyces cerevisiae in response to nutrient availability

MOLECULAR MICROBIOLOGY, Issue 1 2003
Marco Gagiano
Summary In Saccharomyces cerevisiae, the cell surface protein, Muc1p, was shown to be critical for invasive growth and pseudohyphal differentiation. The transcription of MUC1 and of the co-regulated STA2 glucoamylase gene is controlled by the interplay of a multitude of regulators, including Ste12p, Tec1p, Flo8p, Msn1p and Mss11p. Genetic analysis suggests that Mss11p plays an essential role in this regulatory process and that it functions at the convergence of at least two signalling cascades, the filamentous growth MAPK cascade and the cAMP-PKA pathway. Despite this central role in the control of filamentous growth and starch metabolism, the exact molecular function of Mss11p is unknown. We subjected Mss11p to a detailed molecular analysis and report here on its role in transcriptional regulation, as well as on the identification of specific domains required to confer transcriptional activation in response to nutritional signals. We show that Mss11p contains two independent transactivation domains, one of which is a highly conserved sequence that is found in several proteins with unidentified function in mammalian and invertebrate organisms. We also identify conserved amino acids that are required for the activation function. [source]


CD109, a new marker for myoepithelial cells of mammary, salivary, and lacrimal glands and prostate basal cells

PATHOLOGY INTERNATIONAL, Issue 5 2007
Masaki Hasegawa
The CD109 gene encodes a glycosylphosphatidylinositol (GPI)-anchored cell surface protein. Herein it is shown that CD109 is highly expressed in myoepithelial cells of mammary, salivary, and lacrimal glands; and in prostate basal cells. The anti-CD109 antibody generated by the authors was available for formalin-fixed paraffin section, and it strongly stained myoepithelial cells and basal cells but not ductal, acinar, and secretory cells in these glands. CD109 expression was negative in examined breast ductal carcinomas and prostate adenocarcinomas. These findings indicate that CD109 is a useful marker for the diagnosis of invasive breast and prostate carcinomas. [source]


CD109 expression in squamous cell carcinoma of the uterine cervix

PATHOLOGY INTERNATIONAL, Issue 4 2005
Jing-min Zhang
CD109 is a cell surface protein, a member of the ,2 macroglobulin/C3,C4,C5 family of thioester-containing proteins. The authors have recently reported that high expression of the CD109 gene was detected in approximately half of the examined lung and esophageal squamous cell carcinomas as well as in the testis, and that CD109 has the characteristics of a cancer,testis antigen. In the present study CD109 expression in cervical squamous cell carcinoma was compared with that in endometrial adenocarcinoma by reverse transcription polymerase chain reaction (RT-PCR). The result demonstrated that CD109 expression is significantly higher in cervical squamous cell carcinomas than in endometrial adenocarcinomas and normal cervix and endometrium. In contrast, when expression of RET finger protein (RFP) and bromodomain testis-specific (BRDT) genes, which are also known to be highly expressed in the testis, was examined, no significant difference in their expression levels was observed between squamous cell carcinomas and adenocarcinomas. These findings suggest that CD109 may become a molecular target for the development of new therapeutics for squamous cell carcinoma of various tissue origins. [source]


Transcriptional dynamics of endodermal organ formation

DEVELOPMENTAL DYNAMICS, Issue 1 2009
Richard I. Sherwood
Abstract Although endodermal organs including the liver, pancreas, and intestine are of significant therapeutic interest, the mechanism by which the endoderm is divided into organ domains during embryogenesis is not well understood. To better understand this process, global gene expression profiling was performed on early endodermal organ domains. This global analysis was followed up by dynamic immunofluorescence analysis of key transcription factors, uncovering novel expression patterns as well as cell surface proteins that allow prospective isolation of specific endodermal organ domains. Additionally, a repressive interaction between Cdx2 and Sox2 was found to occur at the prospective stomach,intestine border, with the hepatic and pancreatic domains forming at this boundary, and Hlxb9 was revealed to have graded expression along the dorsal,ventral axis. These results contribute to understanding the mechanism of endodermal organogenesis and should assist efforts to replicate this process using pluripotent stem cells. Developmental Dynamics 238:29,42, 2009. © 2008 Wiley-Liss, Inc. [source]


New assay to detect low-affinity interactions and characterization of leukocyte receptors for collagen including leukocyte-associated Ig-like receptor-1 (LAIR-1)

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 4 2009
Lei Jiang
Abstract Leukocyte activity is controlled by numerous interactions between membrane receptors and ligands on the cell surface. These interactions are of low affinity making detection difficult. We developed a sensitive assay that could readily detect extremely weak interactions such as that between CD200 and the activating receptor CD200RLa (Kd>500,,M) at the protein level. We used the new technology to screen for interactions of inhibitory receptors for collagens. We confirmed that both human and mouse leukocyte-associated Ig-like receptor-1, and in addition the related inhibitory leukocyte Ig-like receptor subfamily B member 4 (CD85K, Gp49B), bound collagen specifically, whereas other cell surface proteins gave no binding. The monomeric affinities of the interactions were then determined to allow comparison with other leukocyte interactions and indicate conditions when these interactions might lead to inhibitory signals. [source]


The CD200 and CD200 receptor cell surface proteins interact through their N-terminal immunoglobulin-like domains

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2004
Deborah Hatherley
Abstract CD200 (OX2) is a broadly distributed cell surface glycoprotein that interacts with a receptor on myeloid cells (CD200R) involved in regulation of macrophage function. Both CD200 and CD200R contain two Ig superfamily domains like many other leukocyte membrane proteins. Site-directed mutagenesis of CD200R showed that, like CD200, it interacted through its N-terminal domain. This indicated that the cell-cell interaction spans four Ig superfamily domains and this distance is similar to many interactions found between T,cells and antigen-presenting cells. This suggests that this topology is also important in interactions of CD200 on a variety of cells with CD200R on myeloid cells, and comparable contact sites may be important mediating regulation in other cell-cell interactions. The mutagenesis showed that the binding involved the predicted GFCC, face of its N-terminal domain, like that of CD200, suggesting that the interaction evolved from a homotypic interaction. [source]


A semaphorin code defines subpopulations of spinal motor neurons during mouse development

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2005
Samia Cohen
Abstract In the spinal cord, motor neurons (MNs) with similar muscle targets and sensory inputs are grouped together into motor pools. To date, relatively little is known about the molecular mechanisms that control the establishment of pool-specific circuitry. Semaphorins, a large family of secreted and cell surface proteins, are important mediators of developmental processes such as axon guidance and cell migration. Here, we used mRNA in situ hybridization to study the expression patterns of semaphorins and their receptors, neuropilins and plexins, in the embryonic mouse spinal cord. Our data show that semaphorins and their receptors are differentially expressed in MNs that lie in distinct locations within the spinal cord. Furthermore, we report a combinatorial expression of class 3 (secreted) semaphorins and their receptors that characterizes distinct motor pools within the brachial and lumbar spinal cord. Finally, we found that a secreted semaphorin, Sema3A, elicits differential collapse responses in topologically distinct subpopulations of spinal MNs. These findings lead us to propose that semaphorins and their receptors might play important roles in the sorting of motor pools and the patterning of their afferent and efferent projections. [source]


Seropositivity to Helicobacter pylori heat shock protein 60 is strongly associated with intensity of chronic inflammation, particularly in antrum mucosa: an extension of an 18-year follow-up study of chronic gastritis in Saaremaa, Estonia

FEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2001
Tamara Vorobjova
Abstract Helicobacter pylori is a cause of chronic gastritis and leads to development of atrophy in some cases. There is evidence that the heat shock protein 60 (HSP60) of H. pylori is involved in induction of chronic inflammation. Seroprevalence of IgG antibodies to H. pylori HSP60 in an adult cohort from Saaremaa, Estonia (68 persons, median age 57 years), with a high prevalence of antibodies to cell surface proteins of H. pylori (92%) and a well characterized dynamics of chronic gastritis in an 18-year follow-up study, was tested using purified H. pylori HSP60 at a concentration of 1 ,g ml,1 with ELISA. The state of the gastric mucosa and the presence of H. pylori in histological sections in the samples of 1979 and 1997 were assessed in accordance with the Sydney system. Seropositivity for H. pylori HSP60 was 65%. Immunological response to H. pylori HSP60 is associated with the morphological presence of H. pylori in the antrum and corpus (P=0.01) and is strongly correlated with the grade of chronic inflammation, particularly in the antrum mucosa (r=0.34; P=0.003; OR=5.97 (95% CI 1.21,29.3)), but is not associated with development of atrophy during 18 years of follow-up, or with the activity of gastritis. This finding supports the evidence that immunological response to H. pylori HSP60 may play a role in triggering of the inflammatory process in the gastric mucosa. [source]


Starvation-induced changes in the cell surface of Azospirillum lipoferum

FEMS MICROBIOLOGY ECOLOGY, Issue 1 2000
Thelma Castellanos
Abstract Three starvation regimes (a deficient culture medium, a saline buffer solution and distilled water) were evaluated for their possible effect on cell surface characteristics of Azospirillum lipoferum 1842 related to the initial adsorption of the bacterium to surfaces. The bacteria survived for 7 days in all media although they did not multiply. Upon transfer from a rich growth medium (nutrient agar) to starvation conditions, cell surface hydrophobicity dropped sharply but recovered its initial value within 24 to 48 h, except in phosphate-buffered saline, the length of the recovery period depending on the starvation medium. Starvation affected the sugar affinity of the A. lipoferum cell surface mainly towards p -aminophenyl-,- D -mannopyranoside, to a lesser extent to glucose, but not to other monosaccharides tested. Starvation changed the concentration of several cell surface proteins but did not induce the synthesis of new ones. The cell surface hydrophobic protein (43 kDa) of A. lipoferum 1842 was unaffected by any starvation treatment for a period of up to 48 h, but later disappeared. These data showed that starvation is not a major factor in inducing changes in the cell surface which lead to the primary phase of attachment of Azospirillum to surfaces. [source]


L-selectin and E-selectin expressed on monocytes mediating Ehrlichia chaffeensis attachment onto host cells

FEMS MICROBIOLOGY LETTERS, Issue 2 2003
Jian-zhi Zhang
Abstract Ehrlichia chaffeensis, the agent of human monocytic ehrlichiosis, is an obligatory intracellular bacterium that exhibits monocytic host cell tropism. Ehrlichiae must enter the host cell, and then establish infection. The tropism of E. chaffeensis for monocytes suggests that the cell contains some specific surface components that mediate E. chaffeensis attachment and entry into host cells. In this study, host cell surface components that play a role in ehrlichial attachment were identified using a human monocyte/macrophage cell line, THP-1. E. chaffeensis attachment to THP-1 cells was partially blocked in the presence of antibodies to E-selectin and L-selectin, but not by antibodies to P-selectin, integrin ,m, integrin ,x, or normal mouse IgG as determined by real time polymerase chain reaction. Conversely, in HeLa cells that do not exhibit surface expression of E-selectin and L-selectin, antibodies to these cell surface proteins did not inhibit E. chaffeensis attachment. These findings indicate that E-selectin and L-selectin are cell surface proteins that might act as co-receptors and contribute to E. chaffeensis attachment and entry into THP-1. [source]


Phosphatidylinositol 3-phosphate 5-kinase is required for the cellular response to nutritional starvation and mating pheromone signals in Schizosaccharomyces pombe

GENES TO CELLS, Issue 2 2002
Masayo Morishita
Background: Phosphatidylinositol (3,5) bisphosphate, which is converted from phosphatidylinositol 3-phosphate by phosphatidylinositol 3-phosphate 5-kinase, is implicated in vacuolar functions and the sorting of cell surface proteins within endosomes in the endocytic pathway of budding yeast. A homologous protein, SpFab1p, has been found in the fission yeast Schizosaccharomyces pombe, but its role is not known. Results: Here we report that SpFab1p is encoded by ste12+ known as a fertility gene in S. pombe. The ste12 mutant grew normally under stress-free conditions, but was highly vacuolated and swelled at high temperatures and under starvation conditions. In nitrogen-free medium, ste12 cells were arrested in G1 phase, but partially defective in the expression of genes responsible for mating and meiosis. The ste12 mutant was defective both in the production of, and in the response to, mating pheromones. The amount of the pheromone receptor protein Map3p, was substantially decreased in ste12 cells. Map3p was transported to the cell surface, then internalized and eventually transported to the vacuolar lumen, even in the ste12 mutant. Conclusion: The results indicate that phosphatidylinositol(3,5)bisphosphate is essential for cellular responses to various stresses and for the mating pheromone signalling under starvation conditions. [source]


Immunoblot Analysis as an Alternative Method to Diagnose Enterohepatic Helicobacter Infections

HELICOBACTER, Issue 3 2009
Torkel Wadström
Abstract Introduction: Enterohepatic Helicobacter species have been associated with chronic infections of the hepatobiliary tract and lower bowel in naturally and experimentally infected mice, Helicobacter -infected animals should thus not be used in studies of diseases associated with chronic inflammation. Helicobacter species induce inflammation and modulate host immune responses, thus emphasizing the need to diagnose these infections in laboratory animals. Materials and Methods: An immunoblot assay was developed to analyze antibodies to enterohepatic Helicobacter species in naturally colonized laboratory mouse colonies. We evaluated the serum antibody responses to cell surface proteins of H. bilis, H. hepaticus, and H. ganmani in 188 mouse sera from four different university animal facilities. Lower bowel tissue specimens from 56 of these animals were available and analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and the results compared with matched immunoblot patterns. Results: Specific antibody reactivity to H. bilis was detected in 8 of 186 (4.3%) sera, to H. hepaticus in 45 of 184 (24%) sera, and to H. ganmani in 51 of 188 (27%) of tested sera. These results were compared with PCR-DGGE analyses of tissue samples of corresponding animals, and concordance between the two diagnostic tests was found in 96% for H. bilis, in 91% for H. hepaticus, and in 82% for H. ganmani. The PCR-DGGE also detected DNA of H. typhlonius, H. sp. flexispira, and H. rodentium. Conclusions: Infection with enterohepatic species was common in the laboratory mouse colonies tested, independent of strain and stock. Immunoblot analysis seems to be a promising diagnostic tool to monitor enterohepatic Helicobacter species infections of laboratory rodents. [source]


Role for dipeptidyl peptidase IV in tumor suppression of human non small cell lung carcinoma cells

INTERNATIONAL JOURNAL OF CANCER, Issue 6 2004
Umadevi V. Wesley
Abstract Lung cancer is the leading cause of cancer death. Lung cancers produce a variety of mitogenic growth factors that stimulate tumor cell proliferation and migration. The cell surface protease, dipeptidyl peptidase IV (DPPIV), is involved in diverse biologic functions, including peptide-mediated cellular growth and differentiation. DPPIV is expressed in various normal tissues, including lung tissue, and its expression is lost in many types of human cancers. DPPIV expression and its enzymatic activity are detected in normal bronchial and alveolar epithelium but different histologic subtypes of lung carcinomas lose DPPIV expression. To investigate the role of DPPIV in lung carcinoma, we examined the expression of DPPIV at both mRNA and protein levels in non small cell lung cancer (NSCLC) cell lines and normal human bronchial epithelial cells. DPPIV expression was detectable in normal lung epithelial cells, but was absent or markedly reduced in all NSCLC cell lines at both mRNA and protein levels. Restoration of DPPIV expression in NSCLC cells resulted in profound morphologic changes, inhibition of cell proliferation, anchorage-independent growth, in vitro cell migration and tumorigenicity in nude mice. DPPIV reexpression also correlated with increased p21 expression, leading to induction of apoptosis and cell cycle arrest in G1 stage. These effects were accompanied by increased expression of cell surface proteins, fibroblast-activating protein (Fap,) and CD44 that are associated with suppression of tumor growth and metastasis. Thus, DPPIV functions as a tumor suppressor, and its downregulation may contribute to the loss of growth control in NSCLC cells. © 2004 Wiley-Liss, Inc. [source]


Effects of antibodies against a fusion protein consisting of parts of cell surface protein antigen and glucosyltransferase of Streptococcus sobrinus on cell adhesion of mutans streptococci

MOLECULAR ORAL MICROBIOLOGY, Issue 1 2008
T. Kawato
Background/aims:, The cell surface protein antigen (PAg) and glucosyltransferases (GTFs) produced by Streptococcus sobrinus are considered to be major colonization factors of the organism. Methods:, We constructed a fusion gene encoding a protein composed of the alanine-rich region of PAg (PAgA) and the glucan-binding domain (GB) of GTF-I, which catalyzes the synthesis of water-insoluble glucan in S. sobrinus. The fusion protein PAgA-GB was purified from cell extracts of Escherichia coli harboring the fusion gene, and antibodies against the fusion protein were prepared in rabbits. Results:, In the presence of sucrose, the antibody against PAgA-GB significantly inhibited the adhesion of both S. sobrinus MT8145 and Streptococcus mutans Xc to saliva-coated hydroxyapatite beads, and the inhibitory effect on S. sobrinus was stronger than that on S. mutans. In the absence of sucrose, the antibody against PAgA-GB significantly inhibited the adhesion of both S. sobrinus and S. mutans, however the inhibitory effect on S. sobrinus was unexpectedly weaker than that on S. mutans. A similar result was observed with the antibody against the intact recombinant PAg protein (rPAg), while the same antibody reacted more strongly against S. sobrinus than against S. mutans cells. Conclusion:, Taken together, these results show that the antibody against S. sobrinus GTF-I may be useful for effective inhibition of the sucrose-dependent adhesion of S. sobrinus. However, PAg of S. sobrinus may not function primarily as a receptor for acquired pellicles, and other cell surface proteins may be involved in the sucrose-independent adhesion of S. sobrinus. [source]


Proteolytic cleavage of granulocyte colony-stimulating factor and its receptor by neutrophil elastase induces growth inhibition and decreased cell surface expression of the granulocyte colony-stimulating factor receptor

AMERICAN JOURNAL OF HEMATOLOGY, Issue 3 2003
Melissa G. Hunter
Abstract Neutrophil elastase (NE) is a serine protease stored in the primary granules of neutrophils that proteolytically cleaves multiple cytokines and cell surface proteins on release from activated neutrophils. Recent reports of mutations in the gene encoding this enzyme in some patients with neutropenic syndromes prompted us to investigate whether granulocyte colony-stimulating factor (G-CSF) and its receptor (G-CSFR) are also substrates for NE. To further address this, we examined the effect of NE on G-CSF and the G-CSFR both in solution and on intact cells. Incubation of recombinant G-CSF or a G-CSFR form corresponding to its extracellular domain with purified NE resulted in rapid proteolytic cleavage of both proteins. Addition of NE to tissue culture medium or pretreatment of G-CSF with NE before its addition to media suppressed the growth of G-CSF,responsive cells. NE also cleaved the G-CSFR on the surface of intact cells resulting in a time-dependent reduction in cell surface expression of the G-CSFR. Notably, decreased G-CSFR surface expression resulting from treatment of cells with NE was also associated with a reduction in cell viability and proliferation in response to G-CSF. These results are the first to demonstrate that G-CSF and G-CSFR are proteolytically cleaved by NE and that NE-induced degradation of these proteins correlates with a reduction in the biologic activity of the cytokine and a decrease in the signaling function of the receptor because of decreased G-CSFR surface expression. These findings provide additional insights into mechanisms by which G-CSF/G-CSFR interactions may be modulated. Am. J. Hematol. 74:149,155, 2003. © 2003 Wiley-Liss, Inc. [source]


Rhizobium colonization induced changes in membrane-bound and soluble hydroxyproline-rich glycoprotein composition in pea

PHYSIOLOGIA PLANTARUM, Issue 4 2002
Pål Axel Olsson
Abundance and distribution of plant cell surface proteins of the hydroxyproline-rich glycoprotein (HRGP) class were studied in the pea- Rhizobium symbiosis using immunoblot analysis. The MAC 265-epitope was especially abundant in pea root nodules containing nitrogen-fixing Rhizobium bacteria. A 180-kDa MAC 265-HRGP dominated in pea shoot plasma membranes, while almost no MAC 265-HRGP was detected in root plasma membranes. We show here that a major difference between the plant-derived peribacteroid membrane of the symbiosomes and the root plasma membrane was the presence of a 100-kDa MAC 265-HRGP in the former. Arabinogalactan proteins (AGPs), as recognized by the monoclonal antibodies MAC 207 and JIM 8, were not detected in the peribacteroid membrane, while two isoforms (100 and 220 kDa) were detected in shoot and root plasma membranes. Specific MAC 265-HRGP isoforms were found in the peribacteroid space fraction of the symbiosomes and thus as soluble proteins in the interface between the symbionts. The abundance of the MAC 265-epitope was much reduced in non-nitrogen-fixing nodules when this phenotype resulted from a dicarboxylate transport mutation in Rhizobium. There was no reduction in the abundance of the MAC 265-epitope in non-fixing phenotypes resulting from a mutation in the plant. The results suggest that bacterial signals related to the bacterial ability to fix nitrogen, might be responsible for the regulation of HRGP expression in root nodules. [source]


Atomic force microscopy: A powerful molecular toolkit in nanoproteomics

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 24 2009
Yves F. DufrêneArticle first published online: 7 OCT 200
Abstract Analysing microbial cell surface proteins is a challenging task in current microbial proteomic research, which has major implications for drug design, vaccine development, and microbial monitoring. In this context, atomic force microscopy (AFM) has recently emerged has a powerful characterization platform, providing valuable insights into the surface proteome of microbial cells. The aim of this article is to show how advanced AFM techniques, that all have in common functionalization of the AFM tip with specific molecules, can be used to answer pertinent questions related to surface-associated proteins, such as what is their spatial arrangement on the cell surface, and what are the forces driving their interaction with the environment? [source]


Direct analysis of the extracellular proteome from two strains of Helicobacter pylori

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 13 2007
Todd G. Smith
Abstract Helicobacter pylori extracellular proteins are of interest because of possible roles in pathogenesis, host recognition, and vaccine development. We utilized a unique approach by growing two strains (including one nonsequenced strain) in a defined serum-free medium and directly analyzing the proteins present in the culture supernatants by LC-MS/MS. Over 125 proteins were identified in the extracellular proteomes of two H. pylori strains. Forty-five of these proteins were enriched in the extracellular fraction when compared to soluble cell-associated protein samples. Our analysis confirmed and expanded on the previously reported H. pylori extracellular proteome. Extracellular proteins of interest identified here included cag pathogenicity island protein Cag24 (CagD); proteases HP0657 and HP1012; a polysaccharide deacetylase, HP0310, possibly involved in the hydrolysis of acetyl groups from host N -acetylglucosamine residues or from residues on the cell surface; and HP0953, an uncharacterized protein that appears to be restricted to Helicobacter species that colonize the gastric mucosa. In addition, our analysis found eight previously unidentified outer membrane proteins and two lipoproteins that could be important cell surface proteins. [source]


DIGE compatible labelling of surface proteins on vital cells in vitro and in vivo

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 2 2006
Corina Mayrhofer
Abstract Efficient methods for profiling of the cell surface proteome are desirable to get a deeper insight in basic biological processes, to localise proteins and to uncover proteins differentially expressed in diseases. Here we present a strategy to target cell surface exposed proteins via fluorescence labelling using CyDye DIGE fluors. This method has been applied to human cell lines in vitro as well as to a complex biological system in vivo. It allows detection of fluorophore-tagged cell surface proteins and visualisation of the accessible proteome within a single 2-D gel, simplifying subsequent UV MALDI-MS analysis. [source]


Molecular and Cellular Mechanisms of Ectodomain Shedding

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 6 2010
Kazutaka Hayashida
Abstract The extracellular domain of several membrane-anchored proteins is released from the cell surface as soluble proteins through a regulated proteolytic mechanism called ectodomain shedding. Cells use ectodomain shedding to actively regulate the expression and function of surface molecules, and modulate a wide variety of cellular and physiological processes. Ectodomain shedding rapidly converts membrane-associated proteins into soluble effectors and, at the same time, rapidly reduces the level of cell surface expression. For some proteins, ectodomain shedding is also a prerequisite for intramembrane proteolysis, which liberates the cytoplasmic domain of the affected molecule and associated signaling factors to regulate transcription. Ectodomain shedding is a process that is highly regulated by specific agonists, antagonists, and intracellular signaling pathways. Moreover, only about 2% of cell surface proteins are released from the surface by ectodomain shedding, indicating that cells selectively shed their protein ectodomains. This review will describe the molecular and cellular mechanisms of ectodomain shedding, and discuss its major functions in lung development and disease. Anat Rec, 293:925,937, 2010. © 2010 Wiley,Liss, Inc. [source]


Signalization and cytoskeleton activity through myosin IB during the early steps of phagocytosis in Entamoeba histolytica: a proteomic approach

CELLULAR MICROBIOLOGY, Issue 10 2005
Sabrina Marion
Summary Phagocytosis of human cells is a crucial activity for the virulence of the human parasite Entamoeba histolytica. This protozoan invades and destroys the intestine by killing and phagocytosing epithelial cells, erythrocytes and cells from the immune system. In this study, we used magnetic beads covered with proteins from human serum as a model system to study the early events involved in phagocytosis by E. histolytica. We validated the system showing that the beads uptake triggered the activation of the actin-myosin cytoskeleton and involved a PI3-kinase as previously described for erythrophagocytosis. We purified early phagosomes from wild-type (WT) amoeba and from parasites that overproduced myosin IB (MyoIB+), the unique unconventional myosin of E. histolytica. The MyoIB+ cells exhibit a slower and more synchronized uptake process than the WT strain. Proteomic analysis by liquid chromatography and tandem mass spectroscopy (LC-MS/MS) of the WT and MyoIB+ phagosomes allowed us to identify, for the first time, molecular actors involved in the early step of the uptake process. These include proteins involved in cytoskeleton activity, signalling, endocytosis, lytic activity and cell surface proteins. Interestingly, the proteins that we found specifically recruited on the phagosomes from the MyoIB+ strain were previously described in other eukarytotic cells, as involved in the regulation of cortical F-actin dynamics, such as ,-actinin and formins. This proteomics approach allows a step further towards the understanding of the molecular mechanisms involved in phagocytosis in E. histolytica that revealed some interesting differences compared with phagocytosis in macrophages or Dictyostelium discoideum, and allowed to identify putative candidates for proteins linked to myosin IB activity during the phagocytic process [source]