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Applied and Environmental Microbiology Sep 2022Mushroom-forming fungi () employ enzymatic and nonenzymatic cellulose degradation mechanisms, the latter presumably relying on Fenton-generated radicals. The effects of...
Mushroom-forming fungi () employ enzymatic and nonenzymatic cellulose degradation mechanisms, the latter presumably relying on Fenton-generated radicals. The effects of the two mechanisms on the cellulose microfibrils structure remain poorly understood. We examined cellulose degradation caused by litter decomposers and wood decomposers, including brown-rot and white-rot fungi and one fungus with uncertain wood decay type, by combining small- and wide-angle X-ray scattering. We also examined the effects of commercial enzymes and Fenton-generated radicals on cellulose using the same method. We detected two main degradation or modification mechanisms. The first characterized the mechanism used by most fungi and resembled enzymatic cellulose degradation, causing simultaneous microfibril thinning and decreased crystalline cellulose. The second mechanism was detected in one brown-rot fungus and one litter decomposer and was characterized by patchy amorphogenesis of crystalline cellulose without substantial thinning of the fibers. This pattern did not resemble the effect of Fenton-generated radicals, suggesting a more complex mechanism is involved in the destruction of cellulose crystallinity by fungi. Furthermore, our results showed a mismatch between decay classifications and cellulose degradation patterns and that even within litter decomposers two degradation mechanisms were found, suggesting higher functional diversity under current ecological classifications of fungi. Cellulose degradation by fungi plays a fundamental role in terrestrial carbon cycling, but the mechanisms by which fungi cope with the crystallinity of cellulose are not fully understood. We used X-ray scattering to analyze how fungi, a commercial enzyme mix, and a Fenton reaction-generated radical alter the crystalline structure of cellulose. Our data revealed two mechanisms involved in crystalline cellulose degradation by fungi: one that results in the thinning of the cellulose fibers, resembling the enzymatic degradation of cellulose, and one that involves amorphogenesis of crystalline cellulose by yet-unknown pathways, resulting in a patchy-like degradation pattern. These results pave the way to a deeper understanding of cellulose degradation and the development of novel ways to utilize crystalline cellulose.
Topics: Agaricales; Basidiomycota; Cellulose; Fungi; Lignin; Microfibrils; Wood; X-Rays
PubMed: 35997493
DOI: 10.1128/aem.00995-22 -
Human Molecular Genetics Nov 2018Fibrillin microfibrils are extracellular matrix assemblies that form the template for elastic fibres, endow blood vessels, skin and other elastic tissues with extensible...
Fibrillin microfibrils are extracellular matrix assemblies that form the template for elastic fibres, endow blood vessels, skin and other elastic tissues with extensible properties. They also regulate the bioavailability of potent growth factors of the TGF-β superfamily. A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)10 is an essential factor in fibrillin microfibril function. Mutations in fibrillin-1 or ADAMTS10 cause Weill-Marchesani syndrome (WMS) characterized by short stature, eye defects, hypermuscularity and thickened skin. Despite its importance, there is poor understanding of the role of ADAMTS10 and its function in fibrillin microfibril assembly. We have generated an ADAMTS10 WMS mouse model using Clustered Regularly Spaced Interspaced Short Palindromic Repeats and CRISPR associated protein 9 (CRISPR-Cas9) to introduce a truncation mutation seen in WMS patients. Homozygous WMS mice are smaller and have shorter long bones with perturbation to the zones of the developing growth plate and changes in cell proliferation. Furthermore, there are abnormalities in the ciliary apparatus of the eye with decreased ciliary processes and abundant fibrillin-2 microfibrils suggesting perturbation of a developmental expression switch. WMS mice have increased skeletal muscle mass and more myofibres, which is likely a consequence of an altered skeletal myogenesis. These results correlated with expression data showing down regulation of Growth differentiation factor (GDF8) and Bone Morphogenetic Protein (BMP) growth factor genes. In addition, the mitochondria in skeletal muscle are larger with irregular shape coupled with increased phospho-p38 mitogen-activated protein kinase (MAPK) suggesting muscle remodelling. Our data indicate that decreased SMAD1/5/8 and increased p38/MAPK signalling are associated with ADAMTS10-induced WMS. This model will allow further studies of the disease mechanism to facilitate the development of therapeutic interventions.
Topics: ADAMTS Proteins; Animals; Disease Models, Animal; MAP Kinase Signaling System; Mice; Mice, Transgenic; Microfibrils; Mutation; Signal Transduction; Smad Proteins, Receptor-Regulated; Weill-Marchesani Syndrome
PubMed: 30060141
DOI: 10.1093/hmg/ddy276 -
Scientific Reports Sep 2020Odontoblasts and pulp stroma cells are embedded within supramolecular networks of extracellular matrix (ECM). Fibrillin microfibrils and associated proteins are crucial...
Odontoblasts and pulp stroma cells are embedded within supramolecular networks of extracellular matrix (ECM). Fibrillin microfibrils and associated proteins are crucial constituents of these networks, serving as contextual scaffolds to regulate tissue development and homeostasis by providing both structural and mechanical properties and sequestering growth factors of the TGF-β superfamily. EMILIN-1, -2, and -3 are microfibril-associated glycoproteins known to modulate cell behaviour, growth factor activity, and ECM assembly. So far their expression in the various cells of the dentin-pulp complex during development, in the adult stage, and during inflammation has not been investigated. Confocal immunofluorescence microscopy and western blot analysis of developing and adult mouse molars and incisors revealed an abundant presence of EMILINs in the entire dental papilla, at early developmental stages. Later in development the signal intensity for EMILIN-3 decreases, while EMILIN-1 and -2 staining appears to increase in the pre-dentin and in the ECM surrounding odontoblasts. Our data also demonstrate new specific interactions of EMILINs with fibulins in the dentin enamel junction. Interestingly, in dentin caries lesions the signal for EMILIN-3 was significantly increased in inflamed odontoblasts. Overall our findings point for the first time to a role of EMILINs in dentinogenesis, pulp biology, and inflammation.
Topics: Adolescent; Adult; Animals; Animals, Newborn; Antigens, Surface; Dental Caries; Dental Pulp; Dentin; Glycoproteins; Humans; Incisor; Membrane Glycoproteins; Mice, Inbred C57BL; Molar; Young Adult
PubMed: 32948785
DOI: 10.1038/s41598-020-72123-2 -
The microfibril hypothesis of glaucoma: implications for treatment of elevated intraocular pressure.Journal of Ocular Pharmacology and... 2014Microfibrils are macromolecular aggregates located in the extracellular matrix of both elastic and nonelastic tissues that have essential functions in formation of... (Review)
Review
Microfibrils are macromolecular aggregates located in the extracellular matrix of both elastic and nonelastic tissues that have essential functions in formation of elastic fibers and control of signaling through the transforming growth factor beta (TGFβ) family of cytokines. Elevation of systemic TGFβ and chronic activation of TGFβ signal transduction are associated with diseases caused by mutations in microfibril-associated genes, including FBN1. A role for microfibrils in glaucoma is suggested by identification of risk alleles in LOXL1 for exfoliation glaucoma and mutations in LTBP2 for primary congenital glaucoma, both of which are microfibril-associated genes. Recent identification of a mutation in another microfibril-associated gene, ADAMTS10, in a dog model of primary open-angle glaucoma led us to form the microfibril hypothesis of glaucoma, which in general states that defective microfibrils may be an underlying cause of glaucoma. Microfibril defects could contribute to glaucoma through alterations in biomechanical properties of tissue and/or through effects on signaling through TGFβ, which is well established to be elevated in the aqueous humor of glaucoma patients. Recent work has shown that diseases caused by microfibril defects are associated with increased concentrations of TGFβ protein and chronic activation of TGFβ-mediated signal transduction. In analogy with other microfibril-related diseases, defective microfibrils could provide a mechanism for the elevation of TGFβ2 in glaucomatous aqueous humor. If glaucoma shares mechanisms with other diseases caused by defective microfibrils, such as Marfan syndrome, therapeutic interventions to inhibit chronic activation of TGFβ signaling used in those diseases may be applied to glaucoma.
Topics: Animals; Disease Models, Animal; Dogs; Extracellular Matrix; Glaucoma; Glaucoma, Open-Angle; Humans; Intraocular Pressure; Microfibrils; Mutation; Signal Transduction; Transforming Growth Factor beta
PubMed: 24521159
DOI: 10.1089/jop.2013.0184 -
Plants (Basel, Switzerland) Jan 2020Recent advances in our understanding of the molecular control of secondary cell wall (SCW) formation have shed light on molecular mechanisms that underpin domestication... (Review)
Review
Recent advances in our understanding of the molecular control of secondary cell wall (SCW) formation have shed light on molecular mechanisms that underpin domestication traits related to wood formation. One such trait is the cellulose microfibril angle (MFA), an important wood quality determinant that varies along tree developmental phases and in response to gravitational stimulus. The cytoskeleton, mainly composed of microtubules and actin filaments, collectively contribute to plant growth and development by participating in several cellular processes, including cellulose deposition. Studies in Arabidopsis have significantly aided our understanding of the roles of microtubules in xylem cell development during which correct SCW deposition and patterning are essential to provide structural support and allow for water transport. In contrast, studies relating to SCW formation in xylary elements performed in woody trees remain elusive. In combination, the data reviewed here suggest that the cytoskeleton plays important roles in determining the exact sites of cellulose deposition, overall SCW patterning and more specifically, the alignment and orientation of cellulose microfibrils. By relating the reviewed evidence to the process of wood formation, we present a model of microtubule participation in determining MFA in woody trees forming reaction wood (RW).
PubMed: 31936868
DOI: 10.3390/plants9010090 -
ELife May 2022The embryonic extracellular matrix (ECM) undergoes transition to mature ECM as development progresses, yet few mechanisms ensuring ECM proteostasis during this period...
The embryonic extracellular matrix (ECM) undergoes transition to mature ECM as development progresses, yet few mechanisms ensuring ECM proteostasis during this period are known. Fibrillin microfibrils are macromolecular ECM complexes serving structural and regulatory roles. In mice, and encoding the major microfibrillar components, are strongly expressed during embryogenesis, but fibrillin-1 is the major component observed in adult tissue microfibrils. Here, analysis of and mutant mouse embryos, lacking these homologous secreted metalloproteases individually and in combination, along with in vitro analysis of microfibrils, measurement of ADAMTS6-fibrillin affinities and N-terminomics discovery of ADAMTS6-cleaved sites, identifies a proteostatic mechanism contributing to postnatal fibrillin-2 reduction and fibrillin-1 dominance. The lack of ADAMTS6, alone and in combination with ADAMTS10 led to excess fibrillin-2 in perichondrium, with impaired skeletal development defined by a drastic reduction of aggrecan and cartilage link protein, impaired BMP signaling in cartilage, and increased GDF5 sequestration in fibrillin-2-rich tissue. Although ADAMTS6 cleaves fibrillin-1 and fibrillin-2 as well as fibronectin, which provides the initial scaffold for microfibril assembly, primacy of the protease-substrate relationship between ADAMTS6 and fibrillin-2 was unequivocally established by reversal of the defects in embryos by genetic reduction of , but not .
Topics: ADAMTS Proteins; Animals; Fibrillin-1; Fibrillin-2; Fibrillins; Mice; Microfibrils; Proteolysis
PubMed: 35503090
DOI: 10.7554/eLife.71142 -
Journal of Medical Genetics Oct 2006Marfan syndrome (MFS), a relatively common autosomal dominant hereditary disorder of connective tissue with prominent manifestations in the skeletal, ocular, and... (Review)
Review
Marfan syndrome (MFS), a relatively common autosomal dominant hereditary disorder of connective tissue with prominent manifestations in the skeletal, ocular, and cardiovascular systems, is caused by mutations in the gene for fibrillin-1 (FBN1). The leading cause of premature death in untreated individuals with MFS is acute aortic dissection, which often follows a period of progressive dilatation of the ascending aorta. Recent research on the molecular physiology of fibrillin and the pathophysiology of MFS and related disorders has changed our understanding of this disorder by demonstrating changes in growth factor signalling and in matrix-cell interactions. The purpose of this review is to provide a comprehensive overview of recent advances in the molecular biology of fibrillin and fibrillin-rich microfibrils. Mutations in FBN1 and other genes found in MFS and related disorders will be discussed, and novel concepts concerning the complex and multiple mechanisms of the pathogenesis of MFS will be explained.
Topics: Activin Receptors, Type I; Aortic Dissection; Animals; Aortic Aneurysm, Thoracic; Contractile Proteins; Databases, Genetic; Extracellular Matrix Proteins; Fibrillin-1; Fibrillins; Humans; Latent TGF-beta Binding Proteins; Marfan Syndrome; Mice; Microfibrils; Microfilament Proteins; Models, Animal; Models, Biological; Protein Denaturation; Protein Serine-Threonine Kinases; RNA Splicing Factors; Receptor, Transforming Growth Factor-beta Type I; Receptor, Transforming Growth Factor-beta Type II; Receptors, Transforming Growth Factor beta
PubMed: 16571647
DOI: 10.1136/jmg.2005.039669 -
Nature Structural & Molecular Biology May 2023Genetic mutations in fibrillin microfibrils cause serious inherited diseases, such as Marfan syndrome and Weill-Marchesani syndrome (WMS). These diseases typically show...
Genetic mutations in fibrillin microfibrils cause serious inherited diseases, such as Marfan syndrome and Weill-Marchesani syndrome (WMS). These diseases typically show major dysregulation of tissue development and growth, particularly in skeletal long bones, but links between the mutations and the diseases are unknown. Here we describe a detailed structural analysis of native fibrillin microfibrils from mammalian tissue by cryogenic electron microscopy. The major bead region showed pseudo eightfold symmetry where the amino and carboxy termini reside. On the basis of this structure, we show that a WMS deletion mutation leads to the induction of a structural rearrangement that blocks interaction with latent TGFβ-binding protein-1 at a remote site. Separate deletion of this binding site resulted in the assembly of shorter fibrillin microfibrils with structural alterations. The integrin αβ-binding site was also mapped onto the microfibril structure. These results establish that in complex extracellular assemblies, such as fibrillin microfibrils, mutations may have long-range structural consequences leading to the disruption of growth factor signaling and the development of disease.
Topics: Animals; Microfibrils; Fibrillins; Extracellular Matrix; Transforming Growth Factor beta; Fibrillin-1; Mutation; Binding Sites; Mammals
PubMed: 37081316
DOI: 10.1038/s41594-023-00950-8 -
Plant Physiology Dec 2023Environmental influences and differential growth subject plants to mechanical forces. Forces on the whole plant resolve into tensile forces on its primary cell walls and...
Environmental influences and differential growth subject plants to mechanical forces. Forces on the whole plant resolve into tensile forces on its primary cell walls and both tensile and compression forces on the secondary cell wall layers of woody tissues. Forces on cell walls are further resolved into forces on cellulose microfibrils and the noncellulosic polymers between them. Many external forces on plants oscillate, with time constants that vary from seconds to milliseconds. Sound waves are a high-frequency example. Forces on the cell wall lead to responses that direct the oriented deposition of cellulose microfibrils and the patterned expansion of the cell wall, leading to complex cell and tissue morphology. Recent experiments have established many of the details of which cell wall polymers associate with one another in both primary and secondary cell walls, but questions remain about which of the interconnections are load bearing, especially in primary cell walls. Direct cellulose-cellulose interactions appear to have a more important mechanical role than was previously thought, and some of the noncellulosic polymers may have a role in keeping microfibrils apart rather than cross-linking them as formerly envisaged.
Topics: Cellulose; Plants; Cell Wall; Microfibrils
PubMed: 37403192
DOI: 10.1093/plphys/kiad387 -
Nano Letters Jul 2022Understanding nanoscale moisture interactions is fundamental to most applications of wood, including cellulosic nanomaterials with tailored properties. By combining...
Understanding nanoscale moisture interactions is fundamental to most applications of wood, including cellulosic nanomaterials with tailored properties. By combining X-ray scattering experiments with molecular simulations and taking advantage of computed scattering, we studied the moisture-induced changes in cellulose microfibril bundles of softwood secondary cell walls. Our models reproduced the most important experimentally observed changes in diffraction peak locations and widths and gave new insights into their interpretation. We found that changes in the packing of microfibrils dominate at moisture contents above 10-15%, whereas deformations in cellulose crystallites take place closer to the dry state. Fibrillar aggregation is a significant source of drying-related changes in the interior of the microfibrils. Our results corroborate the fundamental role of nanoscale phenomena in the swelling behavior and properties of wood-based materials and promote their utilization in nanomaterials development. Simulation-assisted scattering analysis proved an efficient tool for advancing the nanoscale characterization of cellulosic materials.
Topics: Cell Wall; Cellulose; Microfibrils; Wood
PubMed: 35767745
DOI: 10.1021/acs.nanolett.2c00822