The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Bo Lönnerdal - One of the best experts on this subject based on the ideXlab platform.
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Nutritional roles of Lactoferrin.
Current opinion in clinical nutrition and metabolic care, 2009Co-Authors: Bo LönnerdalAbstract:Purpose of reviewUntil relatively recently, the only significant source of Lactoferrin in the diet was human Lactoferrin, provided in breast milk. Today, however, bovine Lactoferrin, isolated by dairy technology, as well as recombinant human Lactoferrin are commercially available and can be added to
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Recombinant Human Lactoferrin and Its Variants
Lactoferrin, 1997Co-Authors: Suhasini Iyer, Bo Lönnerdal, Catharine L. Day, Edward N. Baker, John W. Tweedie, Tai-tung Yip, T. William HutchensAbstract:Human Lactoferrin (Lactoferrin) has been shown to bind to receptors present in the human small intestine and on various other types of cells. Little is known about the structural features of the Lactoferrin molecule that are needed for receptor recognition. The Lactoferrin gene has been cloned and sequenced and recombinant Lactoferrin has been expressed in baby hamster kidney cells. The recombinant Lactoferrin has been shown to have normal iron-binding properties, but glycosylation of the recombinant Lactoferrin appears to differ from that of the native Lactoferrin. This expression system has also made it possible to use site-directed mutagenesis to produce variants of human Lactoferrin. In this study, we analyze the physical characteristics as well as the receptor binding properties of recombinant Lactoferrin and its structural variants, including the N-lobe, N-lobe treated with PNGase, and the N-lobe with its glycosylation site (N137A) mutated. Laser-induced desorption/ionization time-of-flight mass spectrometry is used to evaluate differences between the predicted and observed molecular mass values as a function of posttranslational modification. Competitive binding experiments are conducted with both native and recombinant human Lactoferrin to assess receptor binding properties using human brush-border membranes. Each of the recombinant Lactoferrin proteins competes effectively with native Lactoferrin for receptor binding. The N-lobe alone appears to have a greater affinity for the binding sites than does the intact native Lactoferrin. We conclude from these studies that the presence of glycans is not essential for receptor recognition and that the N-lobe of Lactoferrin is both necessary and probably sufficient to allow normal binding to the receptor(s).
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Receptor-mediated binding of milk Lactoferrin to nursing piglet enterocytes: a model for studies on absorption of Lactoferrin-bound iron.
Journal of pediatric gastroenterology and nutrition, 1995Co-Authors: Jóhannes Gíslason, T. W. Hutchens, Gordon C. Douglas, Bo LönnerdalAbstract:Lactoferrin, an iron-binding glycoprotein that is abundant in milk of some species, has been suggested to play a key role in the absorption of iron in human infants. This hypothesis is based on the dominant role of Lactoferrin as an iron-binding component in human milk and on the occurrence of Lactoferrin receptors in brush-border membranes in infants' intestines. The piglet may be a useful model to evaluate the biological activity of Lactoferrin because we have previously found the presence of a Lactoferrin receptor in brush-border membranes from suckling piglets. In this study, viable enterocytes were isolated from 6- to 20-day-old suckling piglets. Binding studies were performed at 4 degrees C using 125I-labeled porcine Lactoferrin. Scatchard analysis of equilibrium binding data showed an apparent binding constant (Kd) of 2 x 10(-6) M (SD = 0.6 x 10(-6)). This affinity is in close agreement with previous results obtained using isolated brush-border membrane vesicles. Bovine Lactoferrin inhibited the binding of porcine Lactoferrin. Porcine transferrin, however, did not affect porcine Lactoferrin binding significantly. Thus, Lactoferrin binding is highly specific. When enterocytes were incubated with 125I-labeled Lactoferrin at 37 degrees C, the amount of cell-associated radioactivity exceeded the surface binding capacity of the cells by almost fivefold. This finding agrees with the continuous binding and subsequent internalization of 125I-labeled Lactoferrin. The isolated piglet enterocyte seems to provide a useful model for further studies of the mechanism of receptor-mediated absorption of Lactoferrin.
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Lactoferrin receptors in intestinal brush border membranes.
Advances in experimental medicine and biology, 1994Co-Authors: Bo LönnerdalAbstract:Lactoferrin from milk may have a physiological effect on the neonate by stimulating iron acquisition and/or mucosal growth. We have hypothesized that in order to achieve such an effect(s), Lactoferrin will bind to a specific receptor located on the mucosal surface of the enterocyte. We have studied the presence of Lactoferrin receptors in the brush border membrane from infant rhesus monkey intestine and from fetal and infant human intestine. The receptor exhibits saturation kinetics and the binding is specific for human and monkey Lactoferrin--bovine Lactoferrin or human transferrin do not bind to the receptor or compete with the binding of the primate Lactoferrins. Enzymatic deglycosylation does not affect the binding of human Lactoferrin to its receptor, suggesting that the glycan(s) is not needed for receptor recognition. Competitive binding experiments showed that holo-Lactoferrin was more effective than less Fe-saturated forms of Lactoferrin with regard to receptor binding. Mn-Lactoferrin bound to the receptor, while we were unable to prepare Zn-Lactoferrin in any physiological buffer. The human Lactoferrin receptor was isolated and found to have a MW of approximately 110 kDa. This receptor has now been cloned and is being sequenced.
Joël Mazurier - One of the best experts on this subject based on the ideXlab platform.
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Advances in Lactoferrin Research - Advances in Lactoferrin research.
Biochimie, 2008Co-Authors: Geneviève Spik, Dominique Legrand, Joël Mazurier, Annick Pierce, Jean-paul PerraudinAbstract:Three-Dimensional Structure of Lactoferrin: Implications for Function, Including Comparisons with Transferrin E.N. Baker, et al. Structures of Buffalo and Mare Lactoferrins: Similarities, Differences, and Flexibility A.K. Sharma, et al. Direct Detection and Quantitative Determination of Bovine Lactoferricin and Lactoferrin Fragments in Human Gastric Contents by Affinity Mass Spectrometry H. Kuwata, et al. Analysis of Bovine Lactoferrin in Whey Using Capillary Electrophoresis (CE) and Micellar Electrokinetic Chromatography (MEKC) P. Riechel, et al. Structural and Immunochemical Studies on Bovine Lactoferrin Fragments K. Shimazaki, et al. Role of the First N-Terminal Basic Cluster of Human Lactoferrin (R2R3R4R5) in the Interactions with the Jurkat Human Lymphoblastic T-Cells D. Legrand, et al. Glycation Ligand Binding Motif in Lactoferrin: Implications in Diabetic Infection Y.M. Li. Mouse Lactoferrin Gene: Promoter-Specific Regulation by EGF and cDNA Cloning of the EGF-Response-Element Binding Protein C. Teng, et al. Cloning of Human Genomic Lactoferrin Sequence and Expression in the Mammary Glands of Transgenic Animals S.J. Kim, et al. 33 Additional Articles. Index.
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Human delta-Lactoferrin is a transcription factor that enhances Skp1 (S-phase kinase-associated protein) gene expression.
FEBS Journal, 2007Co-Authors: Cristophe Mariller, Joël Mazurier, Monique Benaissa, Mathilde Breton, Stephane Hardiville, Guillaume Pradelle, Annick PierceAbstract:Delta-Lactoferrin is a cytoplasmic Lactoferrin isoform that can locate to the nucleus, provoking antiproliferative effects and cell cycle arrest in S phase. Using macroarrays, the expression of genes involved in the G(1)/S transition was examined. Among these, Skp1 showed 2-3-fold increased expression at both the mRNA and protein levels. Skp1 (S-phase kinase-associated protein) belongs to the Skp1/Cullin-1/F-box ubiquitin ligase complex responsible for the ubiquitination of cellular regulators leading to their proteolysis. Skp1 overexpression was also found after delta-Lactoferrin transient transfection in other cell lines (HeLa, MDA-MB-231, HEK 293) at comparable levels. Analysis of the Skp1 promoter detected two sequences that were 90% identical to those previously known to interact with Lactoferrin, the secretory isoform of delta-Lactoferrin (GGCACTGTAC-S1(Skp1), located at - 1067 bp, and TAGAAGTCAA-S2(Skp1), at - 646 bp). Both gel shift and chromatin immunoprecipitation assays demonstrated that delta-Lactoferrin interacts in vitro and in vivo specifically with these sequences. Reporter gene analysis confirmed that delta-Lactoferrin recognizes both sequences within the Skp1 promoter, with a higher activity on S1(Skp1). Deletion of both sequences totally abolished delta-Lactoferrin transcriptional activity, identifying them as delta-Lactoferrin-responsive elements. Delta-Lactoferrin enters the nucleus via a short bipartite RRSDTSLTWNSVKGKK(417-432) nuclear localization signal sequence, which was demonstrated to be functional using mutants. Our results show that delta-Lactoferrin binds to the Skp1 promoter at two different sites, and that these interactions lead to its transcriptional activation. By increasing Skp1 gene expression, delta-Lactoferrin may regulate cell cycle progression via control of the proteasomal degradation of S-phase actors.
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Lactoferrin: a modulator of immune and inflammatory responses.
Cellular and Molecular Life Sciences, 2005Co-Authors: Dominique Legrand, Elisabeth Elass, Mathieu Carpentier, Joël MazurierAbstract:Lactoferrin is an iron-binding glycoprotein of the transferrin family. Abundant expression and secretion of Lactoferrin, in particular in milk and fluids of the digestive tract, are related to its implication in the first line of host defense. Lactoferrin is also a prominent component of the secondary granules of neutrophils (PMNs) and is released in infected tissues and blood during the inflammatory process. In addition to its direct antimicrobial properties, the abilities of Lactoferrin to regulate the immune response and to protect against infection and septic shock have been described in numerous in vitro and in vivo studies. Although the cellular and molecular mechanisms that account for the modulation of the inflammatory and immune responses by Lactoferrin are not yet totally elucidated, many are now established. At the cellular level, Lactoferrin modulates the migration, maturation and function of immune cells. At the molecular level and in addition to iron binding, interactions of Lactoferrin with a plethora of compounds, either soluble or membrane molecules, account for its modulatory properties. This paper reviews our current understanding of the cellular and molecular mechanisms that explain the regulatory properties of Lactoferrin in host defence.
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Lactoferrin inhibits the lipopolysaccharide-induced expression and proteoglycan-binding ability of interleukin-8 in human endothelial cells.
Infection and Immunity, 2002Co-Authors: Elisabeth Elass, Joël Mazurier, Maryse Masson, Dominique LegrandAbstract:Interleukin-8 (IL-8), a C-X-C chemokine bound to endothelium proteoglycans, initiates the activation and selective recruitment of leukocytes at inflammatory foci. We demonstrate that human Lactoferrin, an antimicrobial lipopolysaccharide (LPS)-binding protein, decreases both IL-8 mRNA and protein expression induced by the complex Escherichia coli 055:B5 LPS/sCD14 in human umbilical vein endothelial cells. The use of recombinant Lactoferrins mutated in the LPS-binding sites indicates that this inhibitory effect is mediated by an interaction of Lactoferrin with LPS and CD14s that suppresses the endotoxin biological activity. Furthermore, since dimeric IL-8 and Lactoferrin are both proteoglycan-binding molecules, the competition between these proteins for heparin binding was investigated. Lactoferrin strongly inhibited the interaction of radiolabeled IL-8 to immobilized heparin, whereas a Lactoferrin variant lacking the amino acid residues essential for heparin binding was not inhibitory. Moreover, this process is specific, since serum transferrin, a glycoprotein whose structure is close to that of Lactoferrin, did not prevent the interaction of IL-8 with heparin. These results suggest that the anti-inflammatory properties of Lactoferrin during septicemia are related, at least in part, to the regulation of IL-8 production and also to the ability of Lactoferrin to compete with chemokines for their binding to proteoglycans.
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Lactoferrin: a multifunctional glycoprotein involved in the modulation of the inflammatory process.
Clinical Chemistry and Laboratory Medicine, 1999Co-Authors: Sophie Baveye, Geneviève Spik, Joël Mazurier, Elisabeth Elass, Dominique LegrandAbstract:Lactoferrin is an iron-binding glycoprotein found in exocrine secretions of mammals and released from neutrophilic granules during inflammation. This review describes the biological roles of Lactoferrin in host defence. Secreted Lactoferrin exerts antimicrobial action either by chelation of iron or by destabilization of bacterial membranes. Furthermore, Lactoferrin modulates the inflammatory process, mainly by preventing the release of cytokines from monocytes and by regulating the proliferation and differentiation of immune cells. Some of these activities are related to the ability of Lactoferrin to bind lipopolysaccharides (LPS) with high affinity. Indeed, recent in vitro studies indicate that Lactoferrin is able to compete with the LPS-binding protein for LPS binding and therefore to prevent the transfer of LPS to CD14 present at the surface of monocytes. Moreover, the prophylactic properties of Lactoferrin against septicemia in vivo have been demonstrated. Taken as a whole, these observations strongly suggest that Lactoferrin is one of the key molecules which modulate the inflammatory response.
Dominique Legrand - One of the best experts on this subject based on the ideXlab platform.
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Overview of Lactoferrin as a Natural Immune Modulator
The Journal of Pediatrics, 2016Co-Authors: Dominique LegrandAbstract:Lactoferrin is thought to be the most polyvalent protein present in host defense against tissue injuries and infections in vertebrates. Owing to the propensity of its basic N-terminal domain to interact with various microbial and host targets, Lactoferrin not only has antimicrobial properties, but also modulates the innate and adaptive immune responses. Lactoferrin may indeed up- and downregulate immune cell activation, migration, and growth. Whereas the immunomodulatory properties of Lactoferrin are evidenced from in vivo studies using either Lactoferrin-knockout, Lactoferrin-overexpressing transgenic models, and dietary Lactoferrin, few mechanisms from in vitro studies have been proposed to explain these properties. The best characterized Lactoferrin targets are negatively charged molecules. They encompass pro-inflammatory microbial molecules, such as pathogen-associated molecular patterns (eg, lipopolysaccharide), but also host components such as DNA, the glycosaminoglycan chains of proteoglycans, and surface cell receptors. Signaling through these receptors is thought to be the main lever used by Lactoferrin to influence immune cells and cytokine-balance-controlling cell activity. This article aims to review our current understanding, though incomplete, of the many ways Lactoferrin influences the complex immune machinery and the known and putative mechanisms that may explain its properties.
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Advances in Lactoferrin Research - Advances in Lactoferrin research.
Biochimie, 2008Co-Authors: Geneviève Spik, Dominique Legrand, Joël Mazurier, Annick Pierce, Jean-paul PerraudinAbstract:Three-Dimensional Structure of Lactoferrin: Implications for Function, Including Comparisons with Transferrin E.N. Baker, et al. Structures of Buffalo and Mare Lactoferrins: Similarities, Differences, and Flexibility A.K. Sharma, et al. Direct Detection and Quantitative Determination of Bovine Lactoferricin and Lactoferrin Fragments in Human Gastric Contents by Affinity Mass Spectrometry H. Kuwata, et al. Analysis of Bovine Lactoferrin in Whey Using Capillary Electrophoresis (CE) and Micellar Electrokinetic Chromatography (MEKC) P. Riechel, et al. Structural and Immunochemical Studies on Bovine Lactoferrin Fragments K. Shimazaki, et al. Role of the First N-Terminal Basic Cluster of Human Lactoferrin (R2R3R4R5) in the Interactions with the Jurkat Human Lymphoblastic T-Cells D. Legrand, et al. Glycation Ligand Binding Motif in Lactoferrin: Implications in Diabetic Infection Y.M. Li. Mouse Lactoferrin Gene: Promoter-Specific Regulation by EGF and cDNA Cloning of the EGF-Response-Element Binding Protein C. Teng, et al. Cloning of Human Genomic Lactoferrin Sequence and Expression in the Mammary Glands of Transgenic Animals S.J. Kim, et al. 33 Additional Articles. Index.
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Lactoferrin: a modulator of immune and inflammatory responses.
Cellular and Molecular Life Sciences, 2005Co-Authors: Dominique Legrand, Elisabeth Elass, Mathieu Carpentier, Joël MazurierAbstract:Lactoferrin is an iron-binding glycoprotein of the transferrin family. Abundant expression and secretion of Lactoferrin, in particular in milk and fluids of the digestive tract, are related to its implication in the first line of host defense. Lactoferrin is also a prominent component of the secondary granules of neutrophils (PMNs) and is released in infected tissues and blood during the inflammatory process. In addition to its direct antimicrobial properties, the abilities of Lactoferrin to regulate the immune response and to protect against infection and septic shock have been described in numerous in vitro and in vivo studies. Although the cellular and molecular mechanisms that account for the modulation of the inflammatory and immune responses by Lactoferrin are not yet totally elucidated, many are now established. At the cellular level, Lactoferrin modulates the migration, maturation and function of immune cells. At the molecular level and in addition to iron binding, interactions of Lactoferrin with a plethora of compounds, either soluble or membrane molecules, account for its modulatory properties. This paper reviews our current understanding of the cellular and molecular mechanisms that explain the regulatory properties of Lactoferrin in host defence.
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Lactoferrin inhibits the lipopolysaccharide-induced expression and proteoglycan-binding ability of interleukin-8 in human endothelial cells.
Infection and Immunity, 2002Co-Authors: Elisabeth Elass, Joël Mazurier, Maryse Masson, Dominique LegrandAbstract:Interleukin-8 (IL-8), a C-X-C chemokine bound to endothelium proteoglycans, initiates the activation and selective recruitment of leukocytes at inflammatory foci. We demonstrate that human Lactoferrin, an antimicrobial lipopolysaccharide (LPS)-binding protein, decreases both IL-8 mRNA and protein expression induced by the complex Escherichia coli 055:B5 LPS/sCD14 in human umbilical vein endothelial cells. The use of recombinant Lactoferrins mutated in the LPS-binding sites indicates that this inhibitory effect is mediated by an interaction of Lactoferrin with LPS and CD14s that suppresses the endotoxin biological activity. Furthermore, since dimeric IL-8 and Lactoferrin are both proteoglycan-binding molecules, the competition between these proteins for heparin binding was investigated. Lactoferrin strongly inhibited the interaction of radiolabeled IL-8 to immobilized heparin, whereas a Lactoferrin variant lacking the amino acid residues essential for heparin binding was not inhibitory. Moreover, this process is specific, since serum transferrin, a glycoprotein whose structure is close to that of Lactoferrin, did not prevent the interaction of IL-8 with heparin. These results suggest that the anti-inflammatory properties of Lactoferrin during septicemia are related, at least in part, to the regulation of IL-8 production and also to the ability of Lactoferrin to compete with chemokines for their binding to proteoglycans.
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Lactoferrin: a multifunctional glycoprotein involved in the modulation of the inflammatory process.
Clinical Chemistry and Laboratory Medicine, 1999Co-Authors: Sophie Baveye, Geneviève Spik, Joël Mazurier, Elisabeth Elass, Dominique LegrandAbstract:Lactoferrin is an iron-binding glycoprotein found in exocrine secretions of mammals and released from neutrophilic granules during inflammation. This review describes the biological roles of Lactoferrin in host defence. Secreted Lactoferrin exerts antimicrobial action either by chelation of iron or by destabilization of bacterial membranes. Furthermore, Lactoferrin modulates the inflammatory process, mainly by preventing the release of cytokines from monocytes and by regulating the proliferation and differentiation of immune cells. Some of these activities are related to the ability of Lactoferrin to bind lipopolysaccharides (LPS) with high affinity. Indeed, recent in vitro studies indicate that Lactoferrin is able to compete with the LPS-binding protein for LPS binding and therefore to prevent the transfer of LPS to CD14 present at the surface of monocytes. Moreover, the prophylactic properties of Lactoferrin against septicemia in vivo have been demonstrated. Taken as a whole, these observations strongly suggest that Lactoferrin is one of the key molecules which modulate the inflammatory response.
Jun-mo Yang - One of the best experts on this subject based on the ideXlab platform.
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An antimicrobial protein, Lactoferrin exists in the sweat: proteomic analysis of sweat.
Experimental Dermatology, 2011Co-Authors: Ji Hye Park, Geon Tae Park, Jun-mo YangAbstract:Abstract: The main function of the eccrine gland has been considered to be thermoregulation. Recently, it has been reported that antimicrobial peptides including cathelicidin and dermcidin exist in the sweat. Lactoferrin is found in body fluids such as milk tears and saliva. It is known as a component of host defense against infection and inflammation. In this study, we explored whether Lactoferrin is produced by eccrine glands, thereby establishing its potential role in the skin defense. By immunohistochemistry, Lactoferrin was detected in eccrine glands of normal human skin. In Western blot analysis, Lactoferrin was found in sweat and skin surface substances obtained from healthy volunteers. By proteomic analysis, Lactoferrin and other antimicrobial peptides were detected in sweat. In addition, we measured the concentration of Lactoferrin in sweat by enzyme-linked immunosorbent assay. These findings suggest that Lactoferrin may contribute to skin defense against infection through its secretion in sweat.
Annick Pierce - One of the best experts on this subject based on the ideXlab platform.
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SILAC-Based Proteomic Profiling of the Human MDA-MB-231 Metastatic Breast Cancer Cell Line in Response to the Two Antitumoral Lactoferrin Isoforms: The Secreted Lactoferrin and the Intracellular Delta-Lactoferrin
PloS one, 2014Co-Authors: Esthelle Hoedt, Karima Chaoui, Isabelle Huvent, Christophe Mariller, Bernard Monsarrat, Odile Burlet-schiltz, Annick PierceAbstract:Background: Lactoferrins exhibit antitumoral activities either as a secretory Lactoferrin or an intracellular delta-Lactoferrin isoform. These activities involve processes such as regulation of the cell cycle and apoptosis. While Lactoferrin has been shown to exert its function by activating different transduction pathways, delta-Lactoferrin has been proven to act as a transcription factor. Like many tumor suppressors, these two proteins are under-expressed in several types of cancer, particularly in breast cancer. Methodology/Principal Findings: In order to compare the differential effects of the re-introduction of Lactoferrin isoforms in breast cancer cells we chose the cancerous mammary gland MDA-MB-231 cell line as a model. We produced a cell line stably expressing delta-Lactoferrin. We also treated these cells with fresh purified human breast Lactoferrin. We performed two quantitative proteomic studies in parallel using SILAC coupled to mass spectrometry in order to compare the effects of different doses of the two Lactoferrin isoforms. The proteome of untreated, delta-Lactoferrin expressing and human Lactoferrin treated MDA-MB-231 cells were compared. Overall, around 5300 proteins were identified and quantified using the in-house developed MFPaQ software. Among these, expression was increased by 1.5-fold or more for around 300 proteins in delta-Lactoferrin expressing cells and 190 proteins in Lactoferrin treated cells. At the same time, about 200 and 40 proteins were found to be downregulated (0-0.7-fold) in response to delta-Lactoferrin and Lactoferrin, respectively. Conclusions/Significance: Re-introduction of delta-Lactoferrin and Lactoferrin expression in MDA-MB-231 mainly leads to modifications of protein profiles involved in processes such as proliferation, apoptosis, oxidative stress, the ubiquitin pathway, translation and mRNA quality control. Moreover, this study identified new target genes of delta-Lactoferrin transcriptional activity such as SelH, GTF2F2 and UBE2E1.
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Advances in Lactoferrin Research - Advances in Lactoferrin research.
Biochimie, 2008Co-Authors: Geneviève Spik, Dominique Legrand, Joël Mazurier, Annick Pierce, Jean-paul PerraudinAbstract:Three-Dimensional Structure of Lactoferrin: Implications for Function, Including Comparisons with Transferrin E.N. Baker, et al. Structures of Buffalo and Mare Lactoferrins: Similarities, Differences, and Flexibility A.K. Sharma, et al. Direct Detection and Quantitative Determination of Bovine Lactoferricin and Lactoferrin Fragments in Human Gastric Contents by Affinity Mass Spectrometry H. Kuwata, et al. Analysis of Bovine Lactoferrin in Whey Using Capillary Electrophoresis (CE) and Micellar Electrokinetic Chromatography (MEKC) P. Riechel, et al. Structural and Immunochemical Studies on Bovine Lactoferrin Fragments K. Shimazaki, et al. Role of the First N-Terminal Basic Cluster of Human Lactoferrin (R2R3R4R5) in the Interactions with the Jurkat Human Lymphoblastic T-Cells D. Legrand, et al. Glycation Ligand Binding Motif in Lactoferrin: Implications in Diabetic Infection Y.M. Li. Mouse Lactoferrin Gene: Promoter-Specific Regulation by EGF and cDNA Cloning of the EGF-Response-Element Binding Protein C. Teng, et al. Cloning of Human Genomic Lactoferrin Sequence and Expression in the Mammary Glands of Transgenic Animals S.J. Kim, et al. 33 Additional Articles. Index.
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Human delta-Lactoferrin is a transcription factor that enhances Skp1 (S-phase kinase-associated protein) gene expression.
FEBS Journal, 2007Co-Authors: Cristophe Mariller, Joël Mazurier, Monique Benaissa, Mathilde Breton, Stephane Hardiville, Guillaume Pradelle, Annick PierceAbstract:Delta-Lactoferrin is a cytoplasmic Lactoferrin isoform that can locate to the nucleus, provoking antiproliferative effects and cell cycle arrest in S phase. Using macroarrays, the expression of genes involved in the G(1)/S transition was examined. Among these, Skp1 showed 2-3-fold increased expression at both the mRNA and protein levels. Skp1 (S-phase kinase-associated protein) belongs to the Skp1/Cullin-1/F-box ubiquitin ligase complex responsible for the ubiquitination of cellular regulators leading to their proteolysis. Skp1 overexpression was also found after delta-Lactoferrin transient transfection in other cell lines (HeLa, MDA-MB-231, HEK 293) at comparable levels. Analysis of the Skp1 promoter detected two sequences that were 90% identical to those previously known to interact with Lactoferrin, the secretory isoform of delta-Lactoferrin (GGCACTGTAC-S1(Skp1), located at - 1067 bp, and TAGAAGTCAA-S2(Skp1), at - 646 bp). Both gel shift and chromatin immunoprecipitation assays demonstrated that delta-Lactoferrin interacts in vitro and in vivo specifically with these sequences. Reporter gene analysis confirmed that delta-Lactoferrin recognizes both sequences within the Skp1 promoter, with a higher activity on S1(Skp1). Deletion of both sequences totally abolished delta-Lactoferrin transcriptional activity, identifying them as delta-Lactoferrin-responsive elements. Delta-Lactoferrin enters the nucleus via a short bipartite RRSDTSLTWNSVKGKK(417-432) nuclear localization signal sequence, which was demonstrated to be functional using mutants. Our results show that delta-Lactoferrin binds to the Skp1 promoter at two different sites, and that these interactions lead to its transcriptional activation. By increasing Skp1 gene expression, delta-Lactoferrin may regulate cell cycle progression via control of the proteasomal degradation of S-phase actors.
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Brain Lactoferrin: origins and mechanisms of accumulation in neurodegenerative disorders
2000Co-Authors: Carine Fillebeen, Roméo Cecchelli, David Dexter, Monique Benaissa, Annick PierceAbstract:Several lines of evidence indicate that alterations in iron metabolism and/or immune-mediated pathophysiology might contribute to neuronal loss. Recently, Lactoferrin, an iron-binding protein and a modulatory agent of the inflammatory response, has been associated with neurodegenerative disorders. We have shown that the source of Lactoferrin in brain tissues is double, either synthezised in situ or originating from the circulating blood, and we investigated the mechanisms by which Lactoferrin accumulates in pathological conditions. Lactoferrin is synthezised in situ in the mouse brain. An animal model of Parkinson's disease was used to study the expression of Lactoferrin in pathological conditions. Lactoferrin expression was increased after treatment with MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) which is selectively toxic to the dopaminergic neurons, suggesting that Lactoferrin might be produced in response to the oxidative stress generate by the neurodegenerative process occurring in Parkinson's disease. Lactoferrin crosses the blood-brain barrier (BBB). An in vitro model of the BBB was used to characterize the transport of Lactoferrin through the brain capillary endothelial cells. We next showed, that this transport was increased in inflammatory conditions, leading to Lactoferrin accumulation in the cerebral compartment. This accumulation may account for the increased level of Lactoferrin observed in the vicinity of the inflammatory foci.
