Chondroitin sulfate proteoglycans (CSPGs) are principal pericellular and extracellular components that form regulatory milieu involving numerous biological and pathophysiological phenomena. Diverse ...functions of CSPGs can be mainly attributed to structural variability of their polysaccharide moieties, chondroitin sulfate glycosaminoglycans (CS-GAG). Comprehensive understanding of the regulatory mechanisms for CS biosynthesis and its catabolic processes is required in order to understand those functions.
Here, we focus on recent advances in the study of enzymatic regulatory pathways for CS biosynthesis including successive modification/degradation, distinct CS functions, and disease phenotypes that have been revealed by perturbation of the respective enzymes in vitro and in vivo.
Fine-tuned machineries for CS production/degradation are crucial for the functional expression of CS chains in developmental and pathophysiological processes.
Control of enzymes responsible for CS biosynthesis/catabolism is a potential target for therapeutic intervention for the CS-associated disorders.
•Chondroitin sulfate (CS) chains are implicated in diverse physiological events.•CS chains are also involved in numerous pathophysiological phenomena.•We summarize the functional importance of CS chains.•We focus on how CS chains are constructed by distinct biosynthetic machineries.•Fine-tuning of CS biosynthesis is crucial for the functional expression of CS.
The extracellular matrix (ECM) of the brain is rich in glycosaminoglycans such as chondroitin sulfate (CS) and hyaluronan. These glycosaminoglycans are organized into either diffuse or condensed ECM. ...Diffuse ECM is distributed throughout the brain and fills perisynaptic spaces, whereas condensed ECM selectively surrounds parvalbumin-expressing inhibitory neurons (PV cells) in mesh-like structures called perineuronal nets (PNNs). The brain ECM acts as a non-specific physical barrier that modulates neural plasticity and axon regeneration.
Here, we review recent progress in understanding of the molecular basis of organization and remodeling of the brain ECM, and the involvement of several types of experience-dependent neural plasticity, with a particular focus on the mechanism that regulates PV cell function through specific interactions between CS chains and their binding partners. We also discuss how the barrier function of the brain ECM restricts dendritic spine dynamics and limits axon regeneration after injury.
The brain ECM not only forms physical barriers that modulate neural plasticity and axon regeneration, but also forms molecular brakes that actively controls maturation of PV cells and synapse plasticity in which sulfation patterns of CS chains play a key role. Structural remodeling of the brain ECM modulates neural function during development and pathogenesis.
Genetic or enzymatic manipulation of the brain ECM may restore neural plasticity and enhance recovery from nerve injury.
This article is part of a Special Issue entitled Neuro-glycoscience, edited by Kenji Kadomatsu and Hiroshi Kitagawa.
•The extracellular matrix (ECM) of the brain plays key roles in neural plasticity.•The brain ECM is rich in chondroitin sulfate and hyaluronan.•Several factors influence formation and remodeling of the brain ECM.•Perineuronal nets modulate maturation of parvalbumin-expressing inhibitory neurons.•Perisynaptic ECM controls synapse formation and dendritic spine dynamics.
Chondroitin sulfate (CS) chains, a class of sulfated glycosaminoglycan (GAG) polysaccharides, are ubiquitously distributed in extra/pericellular matrices that establish microenvironmental niches to ...support a multitude of cellular events. Such wide-ranging functions of CS chains are attributable not only to their sulfation pattern-dependent structural divergence, but also to their multiple modes of action. Although it has long been accepted that CS chains act as passive structural scaffolds that often behave as co-receptors and/or reservoirs for various humoral factors, the discovery of cell surface receptor molecules for distinct CS chains has offered insights into a novel mode of CS function as dynamic extra/pericellular signaling ligands. A recent report by Gong et al. (Identification of PTPRσ-interacting proteins by proximity-labeling assay. J. Biochem. 2021; 169:187-194) also strongly reinforced the physiological importance of CS receptor-mediated signaling pathways. In this commentary, we briefly introduce the functional aspects of CS chains as extra/pericellular signaling molecules.
There is untapped potential for materials whose crystal structures are unobtainable in the bulk state. Several examples of such structures have been found in nanomaterials, and these materials ...exhibit unique properties that arise from their unique electronic states and surface structures. Here, recent developments in the syntheses of these nanomaterials and their unique properties, such as hydrogen‐storage ability and catalytic activity, are summarized. Firstly, the syntheses and properties of novel solid‐solution alloy nanoparticles in immiscible alloy systems such as Ag–Rh and Pd–Ru are introduced. Following this, the crystal structure control of nanoscale Ru is discussed. These unique alloy materials show enhanced properties and highlight the potential of phase control to be a new strategy for nanomaterial development.
Recently developed novel nanomaterials with unobtainable crystal structures in the bulk state attract attention with properties different from those of conventional nanomaterials. Recent developments of these materials, including synthesis and properties, are introduced, and their potential as a new strategy of nanomaterial development is discussed.
Proton conductivity through two-dimensional (2-D) hydrogen-bonding networks within a layered metal-organic framework (MOF) (NH4)2(H2adp)Zn2(ox)3·3H2O (H2adp = adipic acid; ox = oxalate) has been ...successfully controlled by cation substitution. We synthesized a cation-substituted MOF, K2(H2adp)Zn2(ox)3·3H2O, where the ammonium ions in a well-defined hydrogen-bonding network are substituted with non-hydrogen-bonding potassium ions, without any apparent change in the crystal structure. We successfully controlled the proton conductivity by cleavage of the hydrogen bonds in a proton-conducting pathway, showing that the 2-D hydrogen-bonding networks in the MOF truly contribute to the high proton conductivity. This is the first example of the control of proton conductivity by ion substitution in a well-defined hydrogen-bonding network within a MOF.
Chondroitin sulfate (CS) chains constitute a class of glycosaminoglycans (GAGs). CS chains are distributed on the surfaces of virtually all cells and throughout most extracellular matrices; they are ...covalently attached to serine residues of core proteoglycan proteins. CS proteoglycans have been implicated as regulators of a variety of biological events, including cell–cell and cell–matrix adhesion, cell proliferation, morphogenesis, and neurite outgrowth. The functional diversity of CS proteoglycans is mainly attributed to the structural variability of the GAG chains, specifically the CS chains. Despite their relatively simple polysaccharide backbones, CS chains acquire remarkable structural variability via several types of enzymatic modifications, including sulfation. Moreover, the sulfation status of CS chains, chain length, number of CS chains per core protein, or combinations thereof can be finely tuned via CS biosynthetic machinery to specify the structure and function of CS proteoglycans. The term “sugar remodeling” refers to the experimental or therapeutic structural alteration of CS chains via perturbation of specific CS biosynthetic enzymes in cells or living organisms; sugar remodeling is a promising approach to the study of CS chain function. This review focuses on our recent findings regarding CS function which have resulted from studies involving sugar remodeling.
One of the key issues for an upcoming hydrogen energy‐based society is to develop highly efficient hydrogen‐storage materials. Among the many hydrogen‐storage materials reported, transition‐metal ...hydrides can reversibly absorb and desorb hydrogen, and have thus attracted much interest from fundamental science to applications. In particular, the Pd−H system is a simple and classical metal‐hydrogen system, providing a platform suitable for a thorough understanding of ways of controlling the hydrogen‐storage properties of materials. By contrast, metal nanoparticles have been recently studied for hydrogen storage because of their unique properties and the degrees of freedom which cannot be observed in bulk, i. e., the size, shape, alloying, and surface coating. In this review, we overview the effects of such degrees of freedom on the hydrogen‐storage properties of Pd‐related nanomaterials, based on the fundamental science of bulk Pd−H. We shall show that sufficiently understanding the nature of the interaction between hydrogen and host materials enables us to control the hydrogen‐storage properties though the electronic‐structure control of materials.
The hydrogen‐storage properties of Pd‐related nanomaterials have been explored by using the degrees of freedom particular to nanomaterials, that is, size, shape, alloying, and metal‐organic framework coating, with a deep understanding of the electronic states based on the fundamental science of the bulk Pd−H system.
A novel metal-organic framework (MOF), (NH(4))(2)(adp)Zn(2)(ox)(3) x 3 H(2)O (1) was synthesized and its structure was determined. We propose three types of rational design to introduce proton ...carriers into MOFs. The simplest method is to introduce them directly as counterions such as NH(4)(+), H(3)O(+), and HSO(4)(-) into the pores of frameworks (type I). The second is to put acid groups on frameworks, the protons being provided from them (type II). The third is to incorporate acidic molecules into voids (type III). 1 demonstrated a combination of two of the concepts by introducing NH(4)(+) ions using the anionic framework (type I) and putting carboxyl end groups of adipic acid in a honeycomb-shaped void (type III). 1 showed a superprotonic conductivity of 10(-2) S cm(-1) at ambient temperature, comparable to organic polymers such as Nafion, which is in practical use in fuel cells. This is the first example of an MOF to exhibit a superprotonic conductivity of 10(-2) S cm(-1) at ambient temperature.
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•An overview of crystalline architectures utilizing Hofmann-type MOFs at the nanoscale.•Thin film fabrication and nanoscale patterning by means of step-by-step technique.•Crystalline ...oriented thin films confirmed by X-ray diffraction study.•Crystal-downsizing effects observed in nanoparticles and thin films.•Potential uses for future optical, electronic and sensing device applications.
Metal–organic frameworks (MOFs) have been of particular interest to researchers because of their structural designability, robustness, and rich science arising from uniform porosity. Among them, Hofmann-type MOFs, which are one of the earliest examples of a MOF, have been intensively studied. For the bulk state of Hofmann-type MOFs, their spin transition behavior induced by guest molecules and external stimuli has long been discussed as a key subject. On the other hand, the use of Hofmann-type MOFs as a nanoscale architecture has recently attracted significant attention toward future practical applications, such as stimuli-responsive sensors and switching devices. In this review, we present an overview of the recent development of fabrication of crystalline architectures at the nanoscale including thin films and nanoparticles utilizing Hofmann-type MOFs.
This study provided an effective strategy to construct dual‐atom sites by solid–solution alloying. A slow synthesis methodology was established for the solid–solution preparations as dual‐atom‐site ...catalysts. The atomic‐level homogeneous PdxRh1−x dual‐atom‐site catalysts were successfully synthesized over the whole composition range, as evidenced by X‐ray powder diffraction and scanning transmission electron microscope energy‐dispersive X‐ray spectroscopy mapping measurements. The challenging morphology formation in the immiscible alloys was achieved by an energy‐controlling process as the octahedral Rh‐rich alloys. The Pd0.3Rh0.7 dual‐atom‐site catalyst had unique surface states to activate the key reactants of CO and NO in the complex three‐way catalytic reactions, and it performed significantly better than pure Rh.
A novel synthetic methodology was established by diminishing the differences in reduction rates for the precursor systems to prepare homogeneous RhxPd1−x solid solutions as a dual‐atom‐site catalyst. The Rh−Pd dual‐atom sites in Pd0.1Rh0.9 and Pd0.3Rh0.7 could activate CO and NO in three‐way catalytic reactions, and showed superior activities over pure Rh.
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