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Nobutaka Wakamiya - One of the best experts on this subject based on the ideXlab platform.
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New Aspects of Collectin Functions
Glycoscience: Biology and Medicine, 2021Co-Authors: Kazuhiro Ohtani, Yasuhiko Suzuki, Nobutaka WakamiyaAbstract:Collectin is a very unique protein, which has two characteristic domains: a collagen-like sequence and carbohydrate recognition domain (CRD). It is considered as a receptor recognizing a pathogen with associated molecular patterns (PAMPs) that play an important role in innate immunity. Recently, it was demonstrated that several Collectins can not only activate the complement pathway but are also involved in various biological functions different from a host defense. In this chapter, we focus on “complement activation-related Collectins,” consisting of mannan-binding lectin (MBL), complement 1q (C1q), collectin kidney 1 (CL-K1), and collectin placenta 1 (CL-P1), and summarize and discuss various new aspects of their functions.
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Chapter 6 – The Collectins
The Complement FactsBook, 2020Co-Authors: Katsuki Ohtani, Nobutaka WakamiyaAbstract:CL-L1 and CL-K1 are the latest discovered Collectins. Collectin is a member of the C-type lectin superfamily having a collagen-like domain and carbohydrate recognition domain. CL-L1 was in the original studies proposed to be a cytosolic protein but it later became clear that it was actually a secreted protein, and it was revealed that CL-L1 forms a heterooligomer with CL-K1 in human blood. They are considered to be secreted mainly by the liver. The heteromeric complex of CL-L1 and CL-K1 was named CL-LK, but it is unknown how this complex is formed. In a study, it was revealed that CL-K1 plays important roles in host defence, complement activation, coagulation and embryonic development.
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Purification, Quantification, and Functional Analysis of Collectins
Methods in molecular biology (Clifton N.J.), 2020Co-Authors: Katsuki Ohtani, Nobutaka WakamiyaAbstract:Native and recombinant Collectins are purified by using mannan-agarose and an anti-collectin antibody column. The use of sandwich enzyme-linked immunosorbent assay (ELISA) with two antibodies against human mannan-binding lectin (MBL) enables elucidation of the collectin concentration in the blood, serum, and plasma. The collectin sugar specificity is demonstrated by determining the concentration of saccharide required to inhibit sugar binding by 50% in a saccharide-binding assay. Biological analyses including the complement-dependent hemolysis test and several other methods are used to evaluate collectin.
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chapter 6 the Collectins
The Complement FactsBook (Second Edition), 2018Co-Authors: Katsuki Ohtani, Nobutaka WakamiyaAbstract:CL-L1 and CL-K1 are the latest discovered Collectins. Collectin is a member of the C-type lectin superfamily having a collagen-like domain and carbohydrate recognition domain. CL-L1 was in the original studies proposed to be a cytosolic protein but it later became clear that it was actually a secreted protein, and it was revealed that CL-L1 forms a heterooligomer with CL-K1 in human blood. They are considered to be secreted mainly by the liver. The heteromeric complex of CL-L1 and CL-K1 was named CL-LK, but it is unknown how this complex is formed. In a study, it was revealed that CL-K1 plays important roles in host defence, complement activation, coagulation and embryonic development.
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the Collectins cl l1 cl k1 and cl p1 and their roles in complement and innate immunity
Immunobiology, 2016Co-Authors: Soren Hansen, Katsuki Ohtani, Nobutaka WakamiyaAbstract:Both the complement system and Collectins play important roles in our innate immune system. The Collectins, which are characterized by their inclusion of a collagen-like region and a calcium-dependent carbohydrate recognition domain, are pattern recognition molecules and include the well characterized proteins mannan-binding lectin (MBL) and the surfactant proteins SP-A/-D. Collectin liver 1 (CL-L1), collectin kidney 1 (CL-K1) and collectin placenta 1 (CL-P1) are the most recently discovered Collectins. Although their function is still under investigation, accumulating information suggests that CL-L1, CL-K1 and CL-P1 play important roles in host defense by recognizing a variety of microorganisms and interacting with effector proteins, including complement components. The recent establishment of the existence of CL-K1 in the circulation in form of heteromeric complexes with CL-L1 (known as CL-LK) and its activation of the lectin pathway via MASPs, drew new attention in the complement biology, which was further strengthened by the observed interactions between CL-P1 and CRP-C1q-factor H or properdin. Deficiency of either CL-K1 or MASP-3 has been demonstrated in 3MC syndrome patients with developmental abnormalities, showing that lectin pathway components, regulation and/or activation are essential during the embryonic development; another feature that they most likely share CL-P1. Herein, we discuss the recent characteristics and roles of the Collectins CL-L1, CL-K1 and CL-P1 in the complement system, in innate immunity and their possible association with disease development and pathogenesis.
Soren Hansen - One of the best experts on this subject based on the ideXlab platform.
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the Collectins cl l1 cl k1 and cl p1 and their roles in complement and innate immunity
Immunobiology, 2016Co-Authors: Soren Hansen, Katsuki Ohtani, Nobutaka WakamiyaAbstract:Both the complement system and Collectins play important roles in our innate immune system. The Collectins, which are characterized by their inclusion of a collagen-like region and a calcium-dependent carbohydrate recognition domain, are pattern recognition molecules and include the well characterized proteins mannan-binding lectin (MBL) and the surfactant proteins SP-A/-D. Collectin liver 1 (CL-L1), collectin kidney 1 (CL-K1) and collectin placenta 1 (CL-P1) are the most recently discovered Collectins. Although their function is still under investigation, accumulating information suggests that CL-L1, CL-K1 and CL-P1 play important roles in host defense by recognizing a variety of microorganisms and interacting with effector proteins, including complement components. The recent establishment of the existence of CL-K1 in the circulation in form of heteromeric complexes with CL-L1 (known as CL-LK) and its activation of the lectin pathway via MASPs, drew new attention in the complement biology, which was further strengthened by the observed interactions between CL-P1 and CRP-C1q-factor H or properdin. Deficiency of either CL-K1 or MASP-3 has been demonstrated in 3MC syndrome patients with developmental abnormalities, showing that lectin pathway components, regulation and/or activation are essential during the embryonic development; another feature that they most likely share CL-P1. Herein, we discuss the recent characteristics and roles of the Collectins CL-L1, CL-K1 and CL-P1 in the complement system, in innate immunity and their possible association with disease development and pathogenesis.
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Collectin Liver 1 and Collectin Kidney 1 of the Lectin Complement Pathway Are Associated With Mortality After Kidney Transplantation
American Journal of Transplantation, 2016Co-Authors: J. Smedbråten, Soren Hansen, Solbjørg Sagedal, Anders Åsberg, Anders Hartmann, Halvor Rollag, Geir Mjøen, Morten W. Fagerland, Tom Eirik Mollnes, Steffen ThielAbstract:Kidney transplanted patients still have significantly higher mortality compared with the general population. The innate immune system may play an important role during periods, with suppression of the adaptive immune system. In the present study, two soluble pattern recognition molecules of the innate immune system were investigated, collectin liver 1 (CL-L1) and collectin kidney 1 (CL-K1). Potential associations of their pretransplant levels and long-term graft and recipient survival were examined. The levels of CL-L1 and CL-K1 were measured at the time of transplantation in 382 patients (≥17 years) transplanted in 2000-2001. The cohort was subsequently followed until December 31, 2014. Data on patient and graft survival were obtained from the Norwegian Renal Registry. Both high CL-L1 (≥376 ng/mL) and high CL-K1 (≥304 ng/mL) levels were significantly associated with overall mortality in multivariate Cox analyses with hazard ration (HR) 1.50, 95% confidence interval (CI) 1.09-2.07, p = 0.013 and HR 1.43, 95% CI 1.02-1.99, p = 0.038, respectively. Moreover, high CL-K1 levels were significantly associated with cardiovascular mortality. No association between measured biomarkers and death-censored graft loss was found. Finally, there was a significant correlation between these two Collectins, r = 0.83 (95% CI 0.80-0.86). In conclusion, CL-L1 and CL-K1 were significantly associated with mortality in kidney transplant recipients.
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Structure and function of collectin liver 1 (CL-L1) and collectin 11 (CL-11, CL-K1).
Immunobiology, 2012Co-Authors: Lana Selman, Soren HansenAbstract:Abstract The Collectins are a group of innate immune proteins structurally characterized by their content of a carbohydrate recognition domain and a collagen-like region. Collectin liver 1 (CL-L1) and collectin 11 (CL-11, alias collectin kidney 1, CL-K1) are the more recently described members of this group. Their genomic organization and protein structure reveal many similarities. However, CL-11 is a serum protein, whereas CL-L1 appears to be restricted to the cytosol of cells such as hepatocytes. Specificity analyses of the CRDs reveal some differences in their preferences for saccharides: CL-11 binds most avidly to l -fucose and d -mannose, whereas CL-L1 shows preference for d -mannose, d -fucose, N -acetylglucosamine, and surprisingly also d -galactose. CL-11 binds to various microorganisms including Escherichia coli , Candida albicans and Influenza A virus. Polymorphisms in the CL-11 gene ( COLEC11 ) leading to deficiencies have recently been identified as causative for 3MC syndrome. The 3MC syndrome is associated with a wide spectrum of developmental features including facial dysmorphism, cognitive impairment, hearing loss and vesicorenal anomalies. Similar polymorphic associations were reported for the mannan-binding lectin-associated serine protease 3 (MASP-3), and falls into line with the observation that CL-11 is found in circulating complexes with MASP-1/3. These findings suggest dual or overlapping functions of CL-11 in innate immunity and in fetal development.
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Collectin 11 (CL-11, CL-K1) Is a MASP-1/3–Associated Plasma Collectin with Microbial-Binding Activity
Journal of Immunology, 2010Co-Authors: Soren Hansen, Lana Selman, Nades Palaniyar, Karel Ziegler, Jette Brandt, Anette Kliem, Maiken Jonasson, Mikkel-ole Skjoedt, Ole Haagen Nielsen, Kevan L HartshornAbstract:Collectins play important roles in the innate immune defense against microorganisms. Recently, a new collectin, collectin 11 (CL-11 or CL-K1), was identified via database searches. In present work, we characterize the structural and functional properties of CL-11. Under nonreducing conditions, in gel permeation chromatography recombinant CL-11 forms disulfide-linked oligomers of 100 and 200 kDa. A mAb-based ELISA estimates the concentration of CL-11 in plasma to be 2.1 μg/ml, and the presence of CL-11 in plasma was further verified by Western blotting and mass spectrometry. Mannan-binding lectin-associated serine protease 1 (MASP-1) copurified with CL-11 and the interaction in plasma with MASP-1 and/or MASP-3 was further demonstrated using ELISA. We identified the adrenal glands, the kidneys, and the liver as primary sites of expression. CL-11 lectin activity was demonstrated by ELISA and showed that CL-11 has preference for l-fucose and d-mannose. We finally show that CL-11 binds to intact bacteria, fungi, and viruses and that CL-11 decreases influenza A virus infectivity and forms complexes with DNA. On the basis of the significant concentration of CL-11 in circulation and CL-11’s interaction with various microorganisms and MASP-1 and/or MASP-3, it is conceivable that CL-11 plays a role in activation of the complement system and in the defense against invading microorganisms.
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CL-46, a Novel Collectin Highly Expressed in Bovine Thymus and Liver
Journal of Immunology, 2002Co-Authors: Soren Hansen, Kenneth B M Reid, Dorte Holm, Vivi Moeller, Lars Vitved, Christian Bendixen, Karsten Skjoedt, Uffe HolmskovAbstract:Collectins are oligomeric molecules with C-type lectin domains attached to collagen-like regions via α-helical neck regions. They bind nonself glycoconjugates on the surface of microorganisms and inhibit infection by direct neutralization, agglutination, or opsonization. During the characterization of the gene encoding bovine CL-43 (43-kDa collectin), we identified a novel collectin-gene. We report the cloning and partial characterization of the novel collectin CL-46. The mRNA comprises 1188 nucleotides encoding a protein of 371 aa with an included leader peptide of 20 residues. CL-46 has two cysteine residues in the N-terminal segment, a potential N-glycosylation site in the collagen region, and an extended hydrophilic loop close to the binding site of the carbohydrate recognition domain. It is expressed in the thymus, liver, mammary gland, and tissues of the digestive system. Recombinant CL-46 corresponding to the α-helical neck region and the C-type lectin domain binds preferential N-acetyl-d-glucoseamine and N-acetyl-d-mannoseamine. The gene encoding CL-46 spans ∼10 kb and consists of eight exons, with high structural resemblance to the gene encoding human surfactant protein D. It is located on the bovine chromosome 28 at position q1.8 together with the gene encoding conglutinin and CL-43. Several potential thymus-related cis-regulatory elements were identified in the 5′-upstream sequence, indicating that the expression in thymus may be modulated by signals involved in T cell development.
Katsuki Ohtani - One of the best experts on this subject based on the ideXlab platform.
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Molecular cloning of mouse collectin liver 1.
Bioscience Biotechnology and Biochemistry, 2020Co-Authors: Takao Kawai, Yasuhiko Suzuki, Katsuki Ohtani, Tetsuo Kase, Hiroyuki Keshi, Yoshinori Sakai, Atsushi Fukuoh, Takashi Sakamoto, Masami NozakiAbstract:Collectins are members of the superfamily of vertebrate C-type lectins that contain a collagen-like region, and are involved in first-line host defense. We earlier cloned and characterized a new kind of collectin, collectin liver 1 (CL-L1). In this study, we isolated the mouse homologue of CL-L1 encoding 277 amino acid residues; its deduced protein sequence was 88% identical with human CL-L1. Mouse CL-L1 mRNA was expressed mainly in the liver and stomach, but was found also in muscles, testes, intestines, and embryos. In mouse embryos, the level of CL-L1 mRNA gradually increased with embryonic age. In 16-day-old mouse embryos, CL-L1 mRNA was expressed in the liver, amnion, and visceral yolk sac. The mouse CL-L1 gene, Cll1 was found on chromosome 15 in a region syntenic with human chromosome 8q. CL-L1 was a highly conserved protein in mammals, birds, and fish.
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Identification and Characterization of a Novel Human Collectin CL‐K1
Microbiology and Immunology, 2020Co-Authors: Hiroyuki Keshi, Katsuki Ohtani, Takao Kawai, Wataru Motomura, Takayuki Yoshizaki, Seong-jae Jang, Takashi Sakamoto, Tsuyoshi Katoh, Mitsuko Fukuda, Satoshi KoyamaAbstract:Collectins are a family of C-type lectins with two characteristic structures, collagen like domains and carbohydrate recognition domains. They recognize carbohydrate antigens on microorganisms and act as host-defense. Here we report the cloning and characterization of a novel collectin CL-K1. RT-PCR analyses showed CL-K1 mRNA is present in all organs. The deduced amino acid sequence and the data from immunostaining of CL-K1 cDNA expressing CHO cells revealed that CL-K1 is expressed as a secreted protein. CL-K1 is found in blood by immunoblotting and partial amino acid analyses. CL-K1 showed Ca 2� -dependent sugar binding activity of fucose and weakly mannose but not N-acetyl-galac- tosamine, N-acetyl-glucosamine, or maltose, though mannose-binding lectin (MBL) containing similar amino acid motif. CL-K1 can recognize specially several bacterial saccharides due to specific sugar-binding character. Elucidation of the role of two ancestor Collectins of CL-K1 and CL-L1 could lead to see the bio- logical function of collectin family.
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Chapter 6 – The Collectins
The Complement FactsBook, 2020Co-Authors: Katsuki Ohtani, Nobutaka WakamiyaAbstract:CL-L1 and CL-K1 are the latest discovered Collectins. Collectin is a member of the C-type lectin superfamily having a collagen-like domain and carbohydrate recognition domain. CL-L1 was in the original studies proposed to be a cytosolic protein but it later became clear that it was actually a secreted protein, and it was revealed that CL-L1 forms a heterooligomer with CL-K1 in human blood. They are considered to be secreted mainly by the liver. The heteromeric complex of CL-L1 and CL-K1 was named CL-LK, but it is unknown how this complex is formed. In a study, it was revealed that CL-K1 plays important roles in host defence, complement activation, coagulation and embryonic development.
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Purification, Quantification, and Functional Analysis of Collectins
Methods in molecular biology (Clifton N.J.), 2020Co-Authors: Katsuki Ohtani, Nobutaka WakamiyaAbstract:Native and recombinant Collectins are purified by using mannan-agarose and an anti-collectin antibody column. The use of sandwich enzyme-linked immunosorbent assay (ELISA) with two antibodies against human mannan-binding lectin (MBL) enables elucidation of the collectin concentration in the blood, serum, and plasma. The collectin sugar specificity is demonstrated by determining the concentration of saccharide required to inhibit sugar binding by 50% in a saccharide-binding assay. Biological analyses including the complement-dependent hemolysis test and several other methods are used to evaluate collectin.
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chapter 6 the Collectins
The Complement FactsBook (Second Edition), 2018Co-Authors: Katsuki Ohtani, Nobutaka WakamiyaAbstract:CL-L1 and CL-K1 are the latest discovered Collectins. Collectin is a member of the C-type lectin superfamily having a collagen-like domain and carbohydrate recognition domain. CL-L1 was in the original studies proposed to be a cytosolic protein but it later became clear that it was actually a secreted protein, and it was revealed that CL-L1 forms a heterooligomer with CL-K1 in human blood. They are considered to be secreted mainly by the liver. The heteromeric complex of CL-L1 and CL-K1 was named CL-LK, but it is unknown how this complex is formed. In a study, it was revealed that CL-K1 plays important roles in host defence, complement activation, coagulation and embryonic development.
Uffe Holmskov - One of the best experts on this subject based on the ideXlab platform.
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increasing antiviral activity of surfactant protein d trimers by introducing residues from bovine serum Collectins dissociation of mannan binding and antiviral activity
Scandinavian Journal of Immunology, 2010Co-Authors: Kevan L Hartshorn, Uffe Holmskov, Yoshio Kuroki, Mitchell R White, Grith Lykke Sørensen, Kelly A Smith, James F Head, Erika C CrouchAbstract:Collectins contribute to host defense through interactions with glycoconjugates on pathogen surfaces. We have prepared recombinant trimeric neck and carbohydrate recognition domains (NCRDs) of Collectins and we now show that the NCRDs of bovine conglutinin and CL-46 (like that of CL-43) have greater intrinsic antiviral activity for influenza A virus (IAV) than the human SP-D NCRD (hSP-D-NCRD). The three serum Collectins differ from SP-D by having insertions adjacent to amino acid 325 and substitution of hydrophobic residues for arginine 343. We previously showed that a 3 amino acid (RAK) insertion, as found in CL-43, increases antiviral activity and mannan binding activity of the hSP-D-NCRD, while the substitution of valine at 343, as in conglutinin, more strongly increased these activities. Mannan binding activity of Collectins has been considered to predict for ability to bind to high mannose glycans on viruses or other pathogens. We now show, however, that combined mutants containing the RAK insertion and R343V or R343I substitutions have greatly increased mannan binding ability, but lower IAV binding or inhibiting activity than mutants containing R343V or R343I substitutions only. These findings indicate differences in the recognition of glycan structures of mannan and IAV by the NCRDs and emphasize the importance of the flanking sequences in determining the differing interactions of human SP-D and bovine serum Collectins with mannose-rich glycoconjugates on IAV and other pathogens. Of interest, we show conservation of some monoclonal antibody binding epitopes between bovine collectin NCRDs and hSP-D, suggesting shared structural motifs.
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Viral aggregating and opsonizing activity in collectin trimers.
American Journal of Physiology-lung Cellular and Molecular Physiology, 2009Co-Authors: Kevan L Hartshorn, Uffe Holmskov, Mitchell R White, Tesfaldet Tecle, Grith Lykke Sørensen, Erika C CrouchAbstract:Collectins are collagenous lectins present in blood, respiratory lining fluid, and other mucosal secretions that play important roles in innate defense against infection. The collectin, surfactant protein D (SP-D), limits infection by viruses and bacteria in the respiratory tract, eye, and female genital tract. Multimeric SP-D has strong antiviral activity and is a potent viral and bacterial agglutinin and opsonin; however, trimers composed of the neck and carbohydrate recognition domain (hSP-D-NCRD) of SP-D lack these activities. We now show that, in contrast, a trimeric neck and CRD construct of bovine serum collectin CL-46 induces aggregation of influenza A virus (IAV) and potently increases IAV uptake by neutrophils. CL-46-NCRD showed calcium-dependent and sugar-sensitive binding to both neutrophils and IAV. Replacement of specific residues of the CRD of human SP-D with those found in bovine serum Collectins conferred opsonizing activity. The most effective substitution involved replacement of arginine 343 with valine (hSP-D-NCRD/R343V). hSP-D-NCRD/R343V greatly increased viral uptake by neutrophils and monocytes and also potentiated neutrophil respiratory burst responses. These effects were further increased by cross-linking of hSP-D-NCRD/R343V trimers with MAbs directed against areas of the hSP-D-NCRD not involved in viral binding. Unlike the wild-type human SP-D hSP-D-NCRD, hSP-D-NCRD/R343V also induced viral aggregation. These results indicate that Collectins can act as opsonins for IAV even in the absence of the collagen domain or higher order multimerization. This may involve increased affinity of individual CRDs for glycoconjugates displayed on host cells or the viral envelope.
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Collectins collectin receptors and the lectin pathway of complement activation
Clinical and Experimental Immunology, 2008Co-Authors: Rajneesh Malhotra, Jinhua Lu, Uffe HolmskovAbstract:The Collectins are a group of soluble multimeric lectins, which contain collagenous segments, and resemble the complement protein C1q in aspects of their structures and functions. This group of proteins, which includes MBP, SP-A, SP-D, conglutinin and CL-43, are known to act as opsonins in various circumstances, and are likely to have roles in innate immunity. The focus of current research is to pursue the hypothesis that the Collectins recognize and bind to non-host carbohydrate structures on microorganisms and particles, and participate in the processing or elimination of such material, either by direct interaction with phagocytic cell receptors, or by indirect routes such as complement activation .
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CL-46, a Novel Collectin Highly Expressed in Bovine Thymus and Liver
Journal of Immunology, 2002Co-Authors: Soren Hansen, Kenneth B M Reid, Dorte Holm, Vivi Moeller, Lars Vitved, Christian Bendixen, Karsten Skjoedt, Uffe HolmskovAbstract:Collectins are oligomeric molecules with C-type lectin domains attached to collagen-like regions via α-helical neck regions. They bind nonself glycoconjugates on the surface of microorganisms and inhibit infection by direct neutralization, agglutination, or opsonization. During the characterization of the gene encoding bovine CL-43 (43-kDa collectin), we identified a novel collectin-gene. We report the cloning and partial characterization of the novel collectin CL-46. The mRNA comprises 1188 nucleotides encoding a protein of 371 aa with an included leader peptide of 20 residues. CL-46 has two cysteine residues in the N-terminal segment, a potential N-glycosylation site in the collagen region, and an extended hydrophilic loop close to the binding site of the carbohydrate recognition domain. It is expressed in the thymus, liver, mammary gland, and tissues of the digestive system. Recombinant CL-46 corresponding to the α-helical neck region and the C-type lectin domain binds preferential N-acetyl-d-glucoseamine and N-acetyl-d-mannoseamine. The gene encoding CL-46 spans ∼10 kb and consists of eight exons, with high structural resemblance to the gene encoding human surfactant protein D. It is located on the bovine chromosome 28 at position q1.8 together with the gene encoding conglutinin and CL-43. Several potential thymus-related cis-regulatory elements were identified in the 5′-upstream sequence, indicating that the expression in thymus may be modulated by signals involved in T cell development.
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Distinctive anti-influenza properties of recombinant collectin 43.
The Biochemical journal, 2002Co-Authors: Kevan L Hartshorn, Uffe Holmskov, Soren Hansen, Pengnian Zhang, Joseph Meschi, Tirsit Mogues, Mitchell R White, Erika C CrouchAbstract:Collectins play important roles in innate defence against viral, fungal and bacterial pathogens. CL-43, a bovine serum collectin, which appears to have evolutionarily evolved from surfactant protein D (SP-D), shows unique structural and functional properties. In the present study, we describe the initial characterization of a recombinant CL-43 expressed in mammalian cells. Like natural CL-43, the recombinant is secreted as trimeric forms that show a preference for mannose and N-acetyl mannosamine. The natural and recombinant proteins have significantly higher haemagglutination-inhibiting activity against influenza A virus (IAV) than recombinant trimeric forms of SP-D. In contrast with the more highly multimerized forms of SP-D, namely conglutinin or mannose-binding lectin, CL-43 did not induce viral or bacterial aggregation and did not enhance IAV-induced neutrophil H(2)O(2) generation. Like SP-D, CL-43 also strongly enhanced neutrophil uptake of IAV. However, the mechanism of this enhanced internalization is different from that of SP-D in that it did not require viral aggregation. These studies establish that the trimeric structure of CL-43 is specified by its primary sequence and indicate that this naturally occurring trimeric collectin has unique antiviral activities. These findings could facilitate the development of recombinant Collectins with novel antimicrobial properties.
Kevan L Hartshorn - One of the best experts on this subject based on the ideXlab platform.
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Collectin 11 (CL-11, CL-K1) Is a MASP-1/3–Associated Plasma Collectin with Microbial-Binding Activity
Journal of Immunology, 2010Co-Authors: Soren Hansen, Lana Selman, Nades Palaniyar, Karel Ziegler, Jette Brandt, Anette Kliem, Maiken Jonasson, Mikkel-ole Skjoedt, Ole Haagen Nielsen, Kevan L HartshornAbstract:Collectins play important roles in the innate immune defense against microorganisms. Recently, a new collectin, collectin 11 (CL-11 or CL-K1), was identified via database searches. In present work, we characterize the structural and functional properties of CL-11. Under nonreducing conditions, in gel permeation chromatography recombinant CL-11 forms disulfide-linked oligomers of 100 and 200 kDa. A mAb-based ELISA estimates the concentration of CL-11 in plasma to be 2.1 μg/ml, and the presence of CL-11 in plasma was further verified by Western blotting and mass spectrometry. Mannan-binding lectin-associated serine protease 1 (MASP-1) copurified with CL-11 and the interaction in plasma with MASP-1 and/or MASP-3 was further demonstrated using ELISA. We identified the adrenal glands, the kidneys, and the liver as primary sites of expression. CL-11 lectin activity was demonstrated by ELISA and showed that CL-11 has preference for l-fucose and d-mannose. We finally show that CL-11 binds to intact bacteria, fungi, and viruses and that CL-11 decreases influenza A virus infectivity and forms complexes with DNA. On the basis of the significant concentration of CL-11 in circulation and CL-11’s interaction with various microorganisms and MASP-1 and/or MASP-3, it is conceivable that CL-11 plays a role in activation of the complement system and in the defense against invading microorganisms.
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increasing antiviral activity of surfactant protein d trimers by introducing residues from bovine serum Collectins dissociation of mannan binding and antiviral activity
Scandinavian Journal of Immunology, 2010Co-Authors: Kevan L Hartshorn, Uffe Holmskov, Yoshio Kuroki, Mitchell R White, Grith Lykke Sørensen, Kelly A Smith, James F Head, Erika C CrouchAbstract:Collectins contribute to host defense through interactions with glycoconjugates on pathogen surfaces. We have prepared recombinant trimeric neck and carbohydrate recognition domains (NCRDs) of Collectins and we now show that the NCRDs of bovine conglutinin and CL-46 (like that of CL-43) have greater intrinsic antiviral activity for influenza A virus (IAV) than the human SP-D NCRD (hSP-D-NCRD). The three serum Collectins differ from SP-D by having insertions adjacent to amino acid 325 and substitution of hydrophobic residues for arginine 343. We previously showed that a 3 amino acid (RAK) insertion, as found in CL-43, increases antiviral activity and mannan binding activity of the hSP-D-NCRD, while the substitution of valine at 343, as in conglutinin, more strongly increased these activities. Mannan binding activity of Collectins has been considered to predict for ability to bind to high mannose glycans on viruses or other pathogens. We now show, however, that combined mutants containing the RAK insertion and R343V or R343I substitutions have greatly increased mannan binding ability, but lower IAV binding or inhibiting activity than mutants containing R343V or R343I substitutions only. These findings indicate differences in the recognition of glycan structures of mannan and IAV by the NCRDs and emphasize the importance of the flanking sequences in determining the differing interactions of human SP-D and bovine serum Collectins with mannose-rich glycoconjugates on IAV and other pathogens. Of interest, we show conservation of some monoclonal antibody binding epitopes between bovine collectin NCRDs and hSP-D, suggesting shared structural motifs.
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Viral aggregating and opsonizing activity in collectin trimers.
American Journal of Physiology-lung Cellular and Molecular Physiology, 2009Co-Authors: Kevan L Hartshorn, Uffe Holmskov, Mitchell R White, Tesfaldet Tecle, Grith Lykke Sørensen, Erika C CrouchAbstract:Collectins are collagenous lectins present in blood, respiratory lining fluid, and other mucosal secretions that play important roles in innate defense against infection. The collectin, surfactant protein D (SP-D), limits infection by viruses and bacteria in the respiratory tract, eye, and female genital tract. Multimeric SP-D has strong antiviral activity and is a potent viral and bacterial agglutinin and opsonin; however, trimers composed of the neck and carbohydrate recognition domain (hSP-D-NCRD) of SP-D lack these activities. We now show that, in contrast, a trimeric neck and CRD construct of bovine serum collectin CL-46 induces aggregation of influenza A virus (IAV) and potently increases IAV uptake by neutrophils. CL-46-NCRD showed calcium-dependent and sugar-sensitive binding to both neutrophils and IAV. Replacement of specific residues of the CRD of human SP-D with those found in bovine serum Collectins conferred opsonizing activity. The most effective substitution involved replacement of arginine 343 with valine (hSP-D-NCRD/R343V). hSP-D-NCRD/R343V greatly increased viral uptake by neutrophils and monocytes and also potentiated neutrophil respiratory burst responses. These effects were further increased by cross-linking of hSP-D-NCRD/R343V trimers with MAbs directed against areas of the hSP-D-NCRD not involved in viral binding. Unlike the wild-type human SP-D hSP-D-NCRD, hSP-D-NCRD/R343V also induced viral aggregation. These results indicate that Collectins can act as opsonins for IAV even in the absence of the collagen domain or higher order multimerization. This may involve increased affinity of individual CRDs for glycoconjugates displayed on host cells or the viral envelope.
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inhibition of influenza viral neuraminidase activity by Collectins
Archives of Virology, 2007Co-Authors: Tesfaldet Tecle, Erika C Crouch, Mitchell R White, Kevan L HartshornAbstract:The Collectins, lung surfactant proteins A and D (SP-A and SP-D), contribute to innate host defense against influenza A virus (IAV) in vivo. Although Collectins bind to the viral hemagglutinin (HA) and inhibit early stages of viral infection in vitro, they also bind to the neuraminidase (NA) and inhibit NA activity. We used a variety of NA functional assays, viral strains and recombinant (mutant or wild type) Collectins to characterize the mechanism of NA inhibition. NA inhibition by SP-D correlates with binding of its carbohydrate recognition domain (CRD) to oligomannose oligosaccharides on the viral hemagglutinin (HA). The effects of SP-D are additive with oseltamivir, consistent with differences in mechanism of action. NA inhibition was observed using fetuin or MDCK cells as a substrate, but not in assays using a soluble sialic acid analogue. Collectin multimerization and CRD binding properties are key determinants for NA inhibition. SP-D had greater NA inhibitory activity than mannose-binding lectin, which in turn had greater activity than SP-A. The markedly greater NA inhibitory activity of SP-D compared to SP-A may partly account for the finding that deletion of the SP-D gene in mice has a greater effect on viral replication in vivo.
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porcine pulmonary Collectins show distinct interactions with influenza a viruses role of the n linked oligosaccharides in the carbohydrate recognition domain
Journal of Immunology, 2003Co-Authors: Martin Van Eijk, Henk P Haagsman, Lambert M G Van Golde, Joseph J Batenburg, Mitchell R White, Erika C Crouch, Arie B Vaandrager, Kevan L HartshornAbstract:Influenza A virus (IAV) infections are a major cause of respiratory disease of humans and animals. Pigs can serve as important intermediate hosts for transmission of avian IAV strains to humans, and for the generation of reassortant strains; this may result in the appearance of new pandemic IAV strains in humans. We have studied the role of the porcine lung Collectins surfactant proteins D and A (pSP-D and pSP-A), two important components of the innate immune response against IAV. Hemagglutination inhibition assays revealed that both pSP-D and pSP-A display substantially greater inhibitory activity against IAV strains isolated from human, swine, and horse, than lung Collectins from other animal species. The more potent activity of pSP-D results from interactions mediated by the asparagine-linked oligosaccharide located in the carbohydrate recognition domain of pSP-D, which is absent in SP-Ds from other species characterized to date. Presence of this sialylated oligosaccharide moiety enhances the anti-influenza activity of pSP-D, as demonstrated by assays of viral aggregation, inhibition of infectivity, and neutrophil response to IAV. The greater hemagglutination inhibitory activity of pSP-A is due to porcine-specific structural features of the conserved asparagine-linked oligosaccharide in the carbohydrate recognition domain of SP-A. A more efficient lung collectin-mediated immune response against IAV in pigs may play a role in providing conditions by which pigs can act as “mixing vessel” hosts that can lead to the production of reassortant, pandemic strains of IAV.