Bromine is ubiquitously present in animals as ionic bromide (Br(-)) yet has no known essential function. Herein, we demonstrate that Br(-) is a required cofactor for peroxidasin-catalyzed formation ...of sulfilimine crosslinks, a posttranslational modification essential for tissue development and architecture found within the collagen IV scaffold of basement membranes (BMs). Bromide, converted to hypobromous acid, forms a bromosulfonium-ion intermediate that energetically selects for sulfilimine formation. Dietary Br deficiency is lethal in Drosophila, whereas Br replenishment restores viability, demonstrating its physiologic requirement. Importantly, Br-deficient flies phenocopy the developmental and BM defects observed in peroxidasin mutants and indicate a functional connection between Br(-), collagen IV, and peroxidasin. We establish that Br(-) is required for sulfilimine formation within collagen IV, an event critical for BM assembly and tissue development. Thus, bromine is an essential trace element for all animals, and its deficiency may be relevant to BM alterations observed in nutritional and smoking-related disease. PAPERFLICK:
Mammalian collagen IV Khoshnoodi, Jamshid; Pedchenko, Vadim; Hudson, Billy G.
Microscopy research and technique,
20/May , Volume:
71, Issue:
5
Journal Article
The cellular microenvironment, characterized by an extracellular matrix (ECM), played an essential role in the transition from unicellularity to multicellularity in animals (metazoans), and in the ...subsequent evolution of diverse animal tissues and organs. A major ECM component are members of the collagen superfamily -comprising 28 types in vertebrates - that exist in diverse supramolecular assemblies ranging from networks to fibrils. Each assembly is characterized by a hallmark feature, a protein structure called a triple helix. A current gap in knowledge is understanding the mechanisms of how the triple helix encodes and utilizes information in building scaffolds on the outside of cells. Type IV collagen, recently revealed as the evolutionarily most ancient member of the collagen superfamily, serves as an archetype for a fresh view of fundamental structural features of a triple helix that underlie the diversity of biological activities of collagens. In this Opinion, we argue that the triple helix is a protein structure of fundamental importance in building the extracellular matrix, which enabled animal multicellularity and tissue evolution.
Collagen IV scaffolds assemble through an intricate pathway that begins intracellularly and is completed extracellularly. Multiple intracellular enzymes act in concert to assemble collagen IV ...protomers, the building blocks of collagen IV scaffolds. After being secreted from cells, protomers are activated to initiate oligomerization, forming insoluble networks that are structurally reinforced with covalent crosslinks. Within these networks, embedded binding sites along the length of the protomer lead to the “decoration” of collagen IV triple helix with numerous functional molecules. We refer to these networks as “smart” scaffolds, which as a component of the basement membrane enable the development and function of multicellular tissues in all animal phyla. In this review, we present key molecular mechanisms that drive the assembly of collagen IV smart scaffolds.
The role of the cellular microenvironment in enabling metazoan tissue genesis remains obscure. Ctenophora has recently emerged as one of the earliest-branching extant animal phyla, providing a unique ...opportunity to explore the evolutionary role of the cellular microenvironment in tissue genesis. Here, we characterized the extracellular matrix (ECM), with a focus on collagen IV and its variant, spongin short-chain collagens, of non-bilaterian animal phyla. We identified basement membrane (BM) and collagen IV in Ctenophora, and show that the structural and genomic features of collagen IV are homologous to those of non-bilaterian animal phyla and Bilateria. Yet, ctenophore features are more diverse and distinct, expressing up to twenty genes compared to six in vertebrates. Moreover, collagen IV is absent in unicellular sister-groups. Collectively, we conclude that collagen IV and its variant, spongin, are primordial components of the extracellular microenvironment, and as a component of BM, collagen IV enabled the assembly of a fundamental architectural unit for multicellular tissue genesis.
This study compared the conformation of the antibody epitopes in Goodpasture's disease and Alport's post-transplantation nephritis in search of the pathogenesis of anti–basement membrane ...glomerulonephritis. The authors report evidence that the initiation of such disease depends on the conformation involving perturbation of the quaternary structure of basement-membrane collagen, eliciting an autoimmune response.
Goodpasture's disease is an organ-specific autoimmune disorder characterized by rapidly progressive glomerulonephritis, pulmonary hemorrhage, and glomerular pathological findings that include linear deposits of antibodies along the glomerular basement membrane (GBM) (Figure 1A).
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,
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(For this article we have studied Goodpasture's disease, which describes the specific entity in which the cause of organ dysfunction is proven to be anti-GBM antibodies, in contrast with Goodpasture's syndrome, which is a clinical term used to describe rapidly progressive glomerulonephritis and pulmonary hemorrhage.) Lerner and colleagues
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passively transferred Goodpasture anti-GBM antibodies in a primate model, inducing glomerulonephritis and thereby showing that an autoantibody itself can . . .
Collagen IV comprises the predominant protein network of basement membranes, a specialized extracellular matrix, which underlie epithelia and endothelia. These networks assemble through ...oligomerization and covalent crosslinking to endow mechanical strength and shape cell behavior through interactions with cell-surface receptors. A recently discovered sulfilimine (S=N) bond between a methionine sulfur and hydroxylysine nitrogen reinforces the collagen IV network. We demonstrate that peroxidasin, an enzyme found in basement membranes, catalyzes formation of the sulfilimine bond. Drosophila peroxidasin mutants have disorganized collagen IV networks and torn visceral muscle basement membranes, pointing to a critical role for the enzyme in tissue biogenesis. Peroxidasin generates hypohalous acids as reaction intermediates, suggesting a paradoxically anabolic role for these usually destructive oxidants. This work highlights sulfilimine bond formation as what is to our knowledge the first known physiologic function for peroxidasin, a role for hypohalous oxidants in tissue biogenesis, and a possible role for peroxidasin in inflammatory diseases.
Basement membrane, a specialized ECM that underlies polarized epithelium of eumetazoans, provides signaling cues that regulate cell behavior and function in tissue genesis and homeostasis. A collagen ...IV scaffold, a major component, is essential for tissues and dysfunctional in several diseases. Studies of bovine and Drosophila tissues reveal that the scaffold is stabilized by sulfilimine chemical bonds (S = N) that covalently cross-link methionine and hydroxylysine residues at the interface of adjoining triple helical protomers. Peroxidasin, a heme peroxidase embedded in the basement membrane, produces hypohalous acid intermediates that oxidize methionine, forming the sulfilimine cross-link. We explored whether the sulfilimine cross-link is a fundamental requirement in the genesis and evolution of epithelial tissues by determining its occurrence and evolutionary origin in Eumetazoa and its essentiality in zebrafish development; 31 species, spanning 11 major phyla, were investigated for the occurrence of the sulfilimine cross-link by electrophoresis, MS, and multiple sequence alignment of de novo transcriptome and available genomic data for collagen IV and peroxidasin. The results show that the cross-link is conserved throughout Eumetazoa and arose at the divergence of Porifera and Cnidaria over 500 Mya. Also, peroxidasin, the enzyme that forms the bond, is evolutionarily conserved throughout Metazoa. Morpholino knockdown of peroxidasin in zebrafish revealed that the cross-link is essential for organogenesis. Collectively, our findings establish that the triad—a collagen IV scaffold with sulfilimine cross-links, peroxidasin, and hypohalous acids—is a primordial innovation of the ECM essential for organogenesis and tissue evolution.
Diabetic nephropathy (DN) is a major life-threatening complication of diabetes. Renal lesions affect glomeruli and tubules, but the pathogenesis is not completely understood. Phospholipids and ...glycolipids are molecules that carry out multiple cell functions in health and disease, and their role in DN pathogenesis is unknown. We employed high spatial resolution MALDI imaging MS to determine lipid changes in kidneys of eNOS(-/-) db/db mice, a robust model of DN. Phospholipid and glycolipid structures, localization patterns, and relative tissue levels were determined in individual renal glomeruli and tubules without disturbing tissue morphology. A significant increase in the levels of specific glomerular and tubular lipid species from four different classes, i.e., gangliosides, sulfoglycosphingolipids, lysophospholipids, and phosphatidylethanolamines, was detected in diabetic kidneys compared with nondiabetic controls. Inhibition of nonenzymatic oxidative and glycoxidative pathways attenuated the increase in lipid levels and ameliorated renal pathology, even though blood glucose levels remained unchanged. Our data demonstrate that the levels of specific phospho- and glycolipids in glomeruli and/or tubules are associated with diabetic renal pathology. We suggest that hyperglycemia-induced DN pathogenic mechanisms require intermediate oxidative steps that involve specific phospholipid and glycolipid species.
Goodpasture's (GP) disease is an autoimmune disorder characterized by the deposition of pathogenic autoantibodies in basement membranes of kidney and lung eliciting rapidly progressive ...glomerulonephritis and pulmonary hemorrhage. The principal autoantigen is the α345 network of collagen IV, which expression is restricted to target tissues. Recent discoveries include a key role of chloride and bromide for network assembly, a novel posttranslational modification of the antigen, a sulfilimine bond that crosslinks the antigen, and the mechanistic role of HLA in genetic susceptibility and resistance to GP disease. These advances provide further insights into molecular mechanisms of initiation and progression of GP disease and serve as a basis for developing of novel diagnostic tools and therapies for treatment of Goodpasture's disease.
•Goodpasture's disease is mediated by antibodies to the α345 collagen IV network in basement membranes of kidney and lungs•Pathogenic autoantibodies bind to four conformational epitopes within α3 and α5 subunits of α345 collagen IV NC1 hexamer•Chloride ions play a fundamental role in extracellular assembly of collagen IV networks•Sulfilimine crosslink formed by peroxidasin using bromide, stabilizes Goodpasture's autoantigen and confers immune privilege•T cells and HLA play an central role in genetic susceptibility and resistance to GP disease
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