CS Chains Research Articles

Preparation and characterization of mussel-inspired chitosan/polydopamine films and their feasibility for oral mucosa application

Oral mucosal lesions (OML), which represent a major public health issue worldwide, include any pathological changes in the oral mucosa, such as ulcers, pigmentation, and swelling. Due to its humid and dynamic complex environment, designing oral mucosal preparations poses significant challenges. Drawing inspiration from mussels, this study employed an eco-friendly one-pot strategy for the preparation of chitosan/polydopamine (CS/PDA) films. We demonstrated that CS-induced polymerization of dopamine monomers under acidic conditions, which might be attributed to the large number of hydrogen bonding sites of CS chains. PDA markedly enhances properties of the CS film and exhibits concentration dependence. At the concentration of 1 wt% PDA, the lap-shear strength and tensile strength of CS/PDA films reached 5.01 ± 0.24 kpa and 4.20 ± 0.78 kpa, respectively, indicating that the mucosal adhesion ability was significantly improved. In comparison with the single CS film, the swelling rate of CS/PDA film decreased by about 30 %. Rheological results also showed that the storage modulus returned to 93 % after cyclic large strain, while the single CS film only recovered to 73 %. Moreover, these films demonstrated good biocompatibility and enhanced oral ulcer healing in rats, providing a new and practical option for the local treatment of OML.

A versatile food packaging film fabricated by gallic acid/octanoic acid grafted chitosan: Preparation, characterization, high-efficient cells capture and photodynamic eradication of bacteria and biofilms

This study aims to construct a versatile film fabricated by gallic acid/octanoic acid-grafted-chitosan (GA/OA-g-CS) for high photodynamic antibacterial and antibiofilm efficacy with blue light (BL, 420 nm) irradiation. First, the GA/OA-g-CS conjugates were synthesized by a green radical-induced grafting reaction in the redox system composed of ascorbic acid/hydroxyl peroxide (AA/H2O2). Then, the molecular structural and physicochemical characteristics of the conjugates, as well as the mechanisms of the free radical grafting reaction were further studied. Ascorbate radical (Asc•−) and hydroxyl radical (•OH) were produced in the AA/H2O2 system, and •OH reacted with CS to produce CS macro-radicals (•CS). UV–vis, Fourier transform infrared, nuclear magnetic resonance spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis confirmed that GA/OA was attached onto CS through •OH. Notably, the films constructed by GA/OA-g-CS exhibited robust multi-modal functionalities, including intriguing bacteria-capturing and contact-killing, as well as BL-driven photodynamic sterilization, ascribed to the inherent merits based on the massive photoactive GA, hydrophobic and high membrane affinity of OA within the CS chains. As a result, the GA/OA-g-CS (2:1) film plus BL irradiation can efficiently eradicate Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and their biofilms. After BL irradiation for 30 min, the GA/OA-g-CS (2:1) film showed a reduction of 5.2 Log CFU/mL against E. coli. More importantly, the film with BL irradiation can efficiently not only inhibit the formation of biofilms but also jeopardize the matured biofilms. This research provides a potential platform and promises for applications in active and intelligent food packaging.

Investigation of the structure, rheology and 3D printing characteristics of corn starch regulated by glycyrrhizic acid

This study aimed to construct a novel corn starch-glycyrrhizic acid (CS-GA) ink and systematically investigate the effects of GA on the water distribution, microstructure, rheology and 3D printing properties of CS hydrogels. The results showed that the CS chains could form strong hydrogen bonds with GA molecules, inhibit the formation of short-range ordered structure of CS and reduce the content of B-type starch. The low-field nuclear magnetic results showed that the introduction of GA could increase bound water content in CS-GA hydrogels. With the increase of GA content, the CS-GA hydrogel changed from CS-dominated to a GA-dominated gel network system. Rheological results showed that all samples exhibited typical shear thinning behavior. High GA concentration was beneficial to increasing the self-supporting properties and thixotropic recovery of CS-GA hydrogels. Compared with the pure CS hydrogel, the 3D printing characteristics of CS-GA hydrogels were significantly enhanced due to the increased bound water content and the enhancement of rheological properties. At 40 % GA content, CS-GA hydrogel showed the highest printing accuracy of 96.4 % ± 0.30 %. The printed product could perfectly replicate the preset model. Therefore, this study provided a theoretical basis for regulating starch's rheology and 3D printing characteristics and developing novel food-grade 3D printing inks.

Chitosan-Pd0 nanoparticles encapsulated in Al, Co-pillared montmorillonite by one-pot process

Chitosan-Pd0 (CS-Pd0) nano particles encapsulated in Al, Co-pillared montmorillonite (MMt) nanocomposites were synthesized by a facile one-pot heat treatment method. The MMt was impregnated with Al, Co pillaring reagent, protonated chitosan solution, and Na2PdCl4 solution, followed with a controlled low-temperature (200 °C) heat treatment, resulting in Pd@CS/Al, Co-MMt nanocomposites. Al, Co pillaring effectively expanded the basal spacing of MMt layers from 1.24 nm to 1.82 nm, and generated numerous mesopores in interlayer space, resulting in increase of surface area from 11.8 m2/g to 198.3 m2/g. Due to the well encapsulation of CS chains in the interlayer nano-spaces, the specific surface area of the hybrid nanocomposite underwent a reasonably decrease as the CS content increase. Most of nano-sized Pd species (2–3 nm) chelated with CS chains dispersed well in the interlayer space of the porous Al, Co pillared MMt matrix. The resultant nanocomposite prepared by such facial one-pot process method have similar high comprehensive catalytic performances as applied in coupling reactions to that prepared by regular divided-multistep method. Moreover, it is confirmed that Al pillaring doped with Co and encapsulation of CS chains have synergistic improving effects on the comprehensive catalytic performance of the nanocomposites.

Effects of zeta-potential on enhanced removal of hexavalent chromium by polypyrrole-graft-chitosan biodegradable copolymer

In the present research, chitosan grafted polypyrrole (PPy-g-CS) biodegradable copolymer particles were used as novel adsorbent to remove hexavalent chromium ions, Cr (VI), from water solutions and compared with the PPy. The effects of zeta (ζ)-potentials of these nanoparticles on the uptake properties of Cr(VI) ions were investigated as a function of pH. It was observed that the ζ-potential of PPy was shifted significantly from + 14 mV (pHinitial=4.8 for PPy) to + 47 mV (pHinitial=4.8 for PPy-g-CS) owing to the covalently grafting of polycationic CS chains with PPy chains. Thus, effective sites (−NH3+)for adsorption of Cr(VI) ions were created at the surfaces of the substrate. Adsorption efficiency of the PPy-g-CS copolymer observed to change by changing the pH of the medium which resulted in the variation of ζ-potential. The uptake capability of the PPy-g-CS copolymer increased compared to the pristine PPy. The maximum removal of Cr(VI) at the optimum pH of 4.8 and at 25 °C was 98 % and 73 % for PPy-g-CS and PPy, respectively. The adsorption kinetics was pseudo-second-order and inconsistent with the Freundlich isotherm. According to the thermodynamic parameters, the adsorption was endothermic (ΔH°PPy-g-CS = 7.12 kJ/mol), spontaneous (ΔG°PPy-g-CS = −546.43 kJ/mol) and driven by the increased entropy (ΔS°PPy-g-CS = 247.55 J/mol.K) of the system. In conclusion, the biodegradable PPy-g-CS graft copolymer particles with enhanced positive ζ-potential (+47 mV at pH=4.8) and adsorption capability (128 mg/g) would be a good candidate as an environmentally friendly adsorbent for the removal of negatively charged pollutants from water resources.

Dopamine and Antioxidant Grape Seed Extract loaded chitosan nanoparticles: A preliminary in vitro characterization

Neuronal cell model line SHSY-5Y is extensively adopted when in vitro investigations are related to Parkinson disease (PD) application. Herein, chitosan nanoparticles (CS NPs) were formulated for the co-administration of dopamine (DA) and Grape Seed Extract (GSE) with the aim to gain insight into the interactions occurring between SHSY-5Y and NPs. Following the ionic gelation technique, the mean particle size of the NPs resulted in the range 310–330 nm and the zeta measurements were in the range +16.4 – +35.5 mV. The presence of CS chains on the surface suggested by positive zeta values was also confirmed by FT-IR analysis, whereas storage stability studies upon different temperatures evidenced that, although aggregation occurred, DA autoxidation was prevented because no black suspensions were detected over the time, irrespectively of the temperature assayed. From a biological viewpoint, release studies of CS NPs loaded with DA and GSE showed that in SHSY-5Y cell lines DA accumulation was time-dependent, irrespectively of the presence of GSE. Furthermore, ROS levels and carbonylated proteins both decreased in SHSY-5Y cell line once NPs administering both DA and GSE were incubated, suggesting a significative reduction of oxidative stress which plays a significative role for PD development.

On the Sorbent Ability and Reusability of Graphene-Oxide–Chitosan Aerogels for the Removal of Dyes from Wastewater

One of the most persistent issues affecting people worldwide is water contamination due to the indiscriminate disposal of pollutants, causing severe environmental problems. Dyes are among the most harmful contaminants because of their high chemical stability and consequently difficult degradation. To remove contaminants from water, adsorption is the most widely used and effective method. In this work, we recall the results already published about the synthesis, the characterization and the use of porous graphene-oxide-chitosan aerogels as a sorbent material. Those systems, prepared by mixing GO sheets and CS chains, using APS as a cross-linking agent, and by further lyophilization, were further characterized using nano-computed tomography, supplying more understanding about their micro and nano-structure. Their sorbent ability has been investigated also by the study of their isotherm of adsorption of two different anionic dyes: Indigo Carmine and Cibacron Brilliant Yellow. Those analyses confirmed the potentialities of the aerogels and their affinity for those anionic dyes. Moreover, the possibility of regenerating and reusing the material was evaluated as a key aspect for applications of this kind. The treatment with NaOH, to promote the desorption of adsorbed dyes, and subsequent washing with HCl, to re-protonate the system, ensured the regeneration of the gels and their use in multiple cycles of adsorption with the selected water contaminants.

Chondroitin sulfate glycosaminoglycans function as extra/pericellular ligands for cell surface receptors.

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.

Dual-Cross-linked Liquid Crystal Hydrogels with Controllable Viscoelasticity for Regulating Cell Behaviors.

The liquid crystal properties and viscoelasticity of the natural bone extracellular matrix (ECM) play a decisive role in guiding cell behavior, conducting cell signals, and regulating mineralization. Here, we develop a facile approach for preparing a novel polysaccharide hydrogel with liquid crystal properties and viscoelasticity similar to those of natural bone ECM. First, a series of chitin whisker/chitosan (CHW/CS) hydrogels were prepared by chemical cross-linking with genipin, in which CHW can self-assemble to form cholesteric liquid crystals under ultrasonic treatment and CS chains can enter into the gaps between the helical layers of the CHW cholesteric liquid crystal phase to endow morphological stability and good mechanical properties. Subsequently, the obtained chemically cross-linked liquid crystal hydrogels were immersed into the desired concentration of the NaCl solution to form physical cross-linking. Due to the Hofmeister effect, the as-prepared dual-cross-linked liquid crystal hydrogels showed an enhanced modulus, viscoelasticity similar to that of natural ECM with relatively fast stress relaxation behavior, and fold surface morphology. Compared to both CHW/CS hydrogels without liquid crystal properties and CHW/CS liquid crystal hydrogels without further physical cross-linking, the dual-cross-linked CHW/CS liquid crystal hydrogels are more favorable for the adhesion, proliferation, and osteogenic differentiation of bone marrow mesenchymal stem cells. This approach could inspire the design of hydrogels mimicking the liquid crystal properties and viscoelasticity of natural bone ECM for bone repair.

ChGn-2 Plays a Cardioprotective Role in Heart Failure Caused by Acute Pressure Overload.

BackgroundCardiac extracellular matrix is critically involved in cardiac homeostasis, and accumulation of chondroitin sulfate glycosaminoglycans (CS‐GAGs) was previously shown to exacerbate heart failure by augmenting inflammation and fibrosis at the chronic phase. However, the mechanism by which CS‐GAGs affect cardiac functions remains unclear, especially at the acute phase.Methods and ResultsWe explored a role of CS‐GAG in heart failure using mice with target deletion of ChGn‐2 (chondroitin sulfate N‐acetylgalactosaminyltransferase‐2) that elongates CS chains of glycosaminoglycans. Heart failure was induced by transverse aortic constriction in mice. The role of CS‐GAG derived from cardiac fibroblasts in cardiomyocyte death was analyzed. Cardiac fibroblasts were subjected to cyclic mechanical stretch that mimics increased workload in the heart. Significant CS‐GAGs accumulation was detected in the heart of wild‐type mice after transverse aortic constriction, which was substantially reduced in ChGn‐2‐/‐ mice. Loss of ChGn‐2 deteriorated the cardiac dysfunction caused by pressure overload, accompanied by augmented cardiac hypertrophy and increased cardiomyocyte apoptosis. Cyclic mechanical stretch increased ChGn‐2 expression and enhanced glycosaminoglycan production in cardiac fibroblasts. Conditioned medium derived from the stretched cardiac fibroblasts showed cardioprotective effects, which was abolished by CS‐GAGs degradation. We found that CS‐GAGs elicits cardioprotective effects via dual pathway; direct pathway through interaction with CD44, and indirect pathway through binding to and activating insulin‐like growth factor‐1.ConclusionsOur data revealed the cardioprotective effects of CS‐GAGs; therefore, CS‐GAGs may play biphasic role in the development of heart failure; cardioprotective role at acute phase despite its possible unfavorable role in the advanced phase.

Glycogenes in Oncofetal Chondroitin Sulfate Biosynthesis are Differently Expressed and Correlated With Immune Response in Placenta and Colorectal Cancer.

Oncofetal chondroitin sulfate expression plays an important role in the development of tumors and the pathogenesis of malaria in pregnancy. However, the biosynthesis and functions of these chondroitin sulfates, particularly the tissue-specific regulation either in tumors or placenta, have not been fully elucidated. Here, by examining the glycogenes availability in chondroitin sulfate biosynthesis such as xylosytransferase, chondroitin synthase, sulfotransferase, and epimerase, the conserved or differential CS glycosylation in normal, colorectal cancer (CRC), and placenta tissue were predicted. We found that the expression of seven chondroitin sulfate biosynthetic enzymes, namely B4GALT7, B3GALT6, B3GAT3, CHSY3, CHSY1, CHPF, and CHPF2, were significantly increased, while four other enzymes (XYLT1, CHST7, CHST15, and UST) were decreased in the colon adenocarcinoma (COAD) and rectum adenocarcinoma (READ) patients. In the human placenta, where the distinct chondroitin sulfate is specifically bound with VAR2CSA on Plasmodium parasite-infected RBC, eight chondroitin sulfate biosynthesis enzymes (CSGALNACT1, CSGALNACT2, CHSY3, CHSY1, CHPF, DSE, CHST11, and CHST3) were significantly higher than the normal colon tissue. The similarly up-regulated chondroitin synthases (CHSY1, CHSY3, and CHPF) in both cancer tissue and human placenta indicate an important role of the proteoglycan CS chains length for Plasmodium falciparum VAR2CSA protein binding. Interestingly, twelve highly expressed chondroitin sulfate enzymes were significantly correlated to worse outcomes (prognosis) in both COAD and READ. Furthermore, we showed that the levels of chondroitin sulfate enzymes are significantly correlated with the expression of immuno-regulators and immune infiltration levels in CRCs and placenta, and involved in multiple essential pathways, such as extracellular matrix organization, epithelial-mesenchymal transition, and cell adhesion. Our study provides novel insights into the oncofetal chondroitin sulfate biosynthesis regulation and identifies promising targets and biomarkers of immunotherapy for CRC and malaria in pregnancy.

Chondroitin sulfate n-acetylgalactosaminyltransferase-2 (ChGn-2) plays a significant role in cardiac remodeling and heart failure following pressure overload

Abstract Background Cardiac extracellular matrix (ECM) is critically involved in cardiac homeostasis by providing mechanical support as well as modulating growth factor signaling. Cardiac ECM dysregulation has been shown in heart failure pathogenesis, and accumulation of chondroitin sulfate glycosaminoglycans (CS-GAGs) was previously shown to exacerbate heart failure by augmenting inflammation and fibrosis at the chronic phase. However, it remains unclear whether and the mechanism by which CS-GAGs cause cardiac dysfunction, especially at the acute phase. Purpose The purpose of this study is to elucidate the role of CS-GAGs in heart failure. Methods In this study, we analyzed the role of CS-GAGs in heart failure using mice with target deletion of chondroitin sulfate N-acetylgalactosaminyltransferase (ChGn)-2 that elongates CS chains of GAGs. Heart failure was induced by transverse aortic constriction (TAC) in mice. Since cardiac fibroblasts (CFs) are the primary cells for ECM production in the heart, we explored the role of CF-derived ECM in cardiomyocyte apoptosis. CFs were given stretch stimuli that mimic pressure overload conditions. Results Significant CS-GAGs accumulation was detected in the heart of WT mice after TAC, which was substantially reduced in the heart of ChGn2−/− mice. Unexpectedly, loss of ChGn-2 deteriorated left ventricular systolic dysfunction accompanied by augmented cardiac hypertrophy and increased cardiomyocyte apoptosis. Stretch stimuli increased ChGn-2 expression and enhanced GAG production in CFs. Interestingly, only conditioned medium (CM) derived from stretched CFs showed protective effects on cardiomyocyte death induced by doxorubicin. Degradation of CS-GAGs in CFs-derived CM by using Chondroitinase ABC abolished its cardioprotective effect. Further experiments revealed that this cardioprotective effect is at least partially through CS-GAGs-derived PI3K/AKT pathway activation via CD44. Conclusion Our data revealed that CF-derived GAGs protect cardiomyocytes from death in the acute phase of heart failure due to pressure overload; thus, insufficient GAGs production caused by loss of ChGn-2 exacerbated heart failure. Funding Acknowledgement Type of funding sources: None.

High-strength and self-healable poly (acrylic acid) /chitosan hydrogel with organic-inorganic hydrogen bonding networks

Bentonite is a natural clay mineral with high cationic exchange properties and plays an important role in organic-inorganic composite hydrogels. We report an organic-inorganic cross-linked self-healing hydrogel with excellent mechanical properties by introducing acrylic acid-modified bentonite (AABT) into its cross-link network. AABT with unsaturated double bonds was co-polymerized with AA to construct the hybrid cross-link network of the hydrogel. Then, the carboxyl groups in the PAA chain reacted with CS to form a physically cross-linked network with a hydrogen bond structure. As confirmed by FTIR, XRD, XPS and SEM, the AABT participated in the formation of the hydrogel network, and the hydrogen bonds between PAA and CS chains were formed. Our AABT-PAA/CS hydrogels possessed tensile strength, compressive modulus and elongation at break as high as 0.96 MPa, 4.5 MPa and 1331%, respectively. Besides, our hydrogels also exhibited excellent self-healing properties, with recovered rate stress and strain of ~76.6% and ~77.7% after 4 h, respectively.

The emerging role of the chondroitin sulfate proteoglycan family in neurodegenerative diseases.

Chondroitin sulfate (CS) is a kind of linear polysaccharide that is covalently linked to proteins to form proteoglycans. Chondroitin sulfate proteoglycans (CSPGs) consist of a core protein, with one or more CS chains covalently attached. CSPGs are precisely regulated and they exert a variety of physiological functions by binding to adhesion molecules and growth factors. Widely distributed in the nervous system in human body, CSPGs contribute to the major component of extracellular matrix (ECM), where they play an important role in the development and maturation of the nervous system, as well as in the pathophysiological response to damage to the central nervous system (CNS). While there are more than 30 types of CSPGs, this review covers the roles of the most important ones, including versican, aggrecan, neurocan and NG2 in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and multiple sclerosis. The updated reports of the treatment of neurodegenerative diseases are involving CSPGs.

Molecular Interactions Stabilizing the Promatrix Metalloprotease-9·Serglycin Heteromer

Previous studies have shown that THP-1 cells produced an SDS-stable and reduction-sensitive complex between proMMP-9 and a chondroitin sulfate proteoglycan (CSPG) core protein. The complex could be reconstituted in vitro using purified serglycin (SG) and proMMP-9 and contained no inter-disulfide bridges. It was suggested that the complex involved both the FnII module and HPX domain of proMMP-9. The aims of the present study were to resolve the interacting regions of the molecules that form the complex and the types of interactions involved. In order to study this, we expressed and purified full-length and deletion variants of proMMP-9, purified CSPG and SG, and performed in vitro reconstitution assays, peptide arrays, protein modelling, docking, and molecular dynamics (MD) simulations. ProMMP-9 variants lacking both the FnII module and the HPX domain did not form the proMMP-9∙CSPG/SG complex. Deletion variants containing at least the FnII module or the HPX domain formed the proMMP-9∙CSPG/SG complex, as did the SG core protein without CS chains. The interacting parts covered large surface areas of both molecules and implicated dynamic and complementary ionic, hydrophobic, and hydrogen bond interactions. Hence, no short single interacting linear motifs in the two macromolecules could explain the strong SDS-stable and reduction-sensitive binding.

Fabrication, characterization and drug release behaviors of chitosan microfibers loaded with herbal or non-herbal drugs

Two chitosan, CS, microfibers loaded with the herbal persimmon leaves, PL, and the non-herbal metformin hydrochloride, MH, were wet spun, respectively. SEM images shown that these two CS microfibers have different surface morphologies at the as-spun state due to the PL-loaded fiber presented the squamae-like structure and the MH-loaded fiber presented some bright dots. This suggested that the PL and MH were loaded in the CS chains by different mechanisms and some loaded MH molecules out of the CS chains might be free and separated by spinning-induced extrusion forces. FTIR spectra analysis indicated that the PL was loaded in the CS chains mainly by the O-H groups and formed the interpenetration network and the MH was loaded in the CS chains mainly by the N-H groups and formed the sheathing structure. The loading of these herbal and non-herbal drugs in CS chains both shown good miscibility while the mechanical properties were reduced as compared with the pure CS fiber. The release of the PL and MH from CS fibers both followed the same Langmuir kinetics model, while the comparisons found that the released amount was greater for the PL and the release rate was faster for the MH.

An affinity chromatography and glycoproteomics workflow to profile the chondroitin sulfate proteoglycans that interact with malarial VAR2CSA in the placenta and in cancer.

Chondroitin sulfate (CS) is the placental receptor for the VAR2CSA malaria protein, expressed at the surface of infected erythrocytes during Plasmodium falciparum infection. Infected cells adhere to syncytiotrophoblasts or get trapped within the intervillous space by binding to a determinant in a 4-O-sulfated CS chains. However, the exact structure of these glycan sequences remains unclear. VAR2CSA-reactive CS is also expressed by tumor cells, making it an attractive target for cancer diagnosis and therapeutics. The identities of the proteoglycans carrying these modifications in placental and cancer tissues remain poorly characterized. This information is clinically relevant since presentation of the glycan chains may be mediated by novel core proteins or by a limited subset of established proteoglycans. To address this question, VAR2CSA-binding proteoglycans were affinity-purified from the human placenta, tumor tissues and cancer cells and analyzed through a specialized glycoproteomics workflow. We show that VAR2CSA-reactive CS chains associate with a heterogenous group of proteoglycans, including novel core proteins. Additionally, this work demonstrates how affinity purification in combination with glycoproteomics analysis can facilitate the characterization of CSPGs with distinct CS epitopes. A similar workflow can be applied to investigate the interaction of CSPGs with other CS binding lectins as well.

Chondrocytes respond to an altered heparan sulfate composition with distinct changes of heparan sulfate structure and increased levels of chondroitin sulfate

Heparan sulfate (HS) regulates the activity of many signaling molecules critical for the development of endochondral bones. Even so, mice with a genetically altered HS metabolism display a relatively mild skeletal phenotype compared to the defects observed in other tissues and organs pointing to a reduced HS dependency of growth-factor signaling in chondrocytes. To understand this difference, we have investigated the glycosaminoglycan (GAG) composition in two mouse lines that produce either reduced levels of HS (Ext1gt/gt mice) or HS lacking 2-O-sulfation (Hs2st1−/− mice). Analysis by RPIP-HPLC revealed an increased level of sulfated disaccarides not affected by the mutation in both mouse lines indicating that chondrocytes attempt to restore a critical level of sulfation. In addition, in both mutant lines we also detected significantly elevated levels of CS. Size exclusion chromatography further demonstrated that Ext1gt/gt mutants produce more but shorter CS chains, while the CS chains produced by (Hs2st1−/− mice) mutants are of similar length to that of wild type littermates indicating that chondrocytes produce more rather than longer CS chains. Expression analysis revealed an upregulation of aggrecan, which likely carries most of the additionally produced CS. Together the results of this study demonstrate for the first time that not only a reduced HS synthesis but also an altered HS structure leads to increased levels of CS in mammalian tissues. Furthermore, as chondrocytes produce 100-fold more CS than HS the increased CS levels point to an active, precursor-independent mechanism that senses the quality of HS in a vast excess of CS. Interestingly, reducing the level of cell surface CS by chondroitinase treatment leads to reduced Bmp2 induced Smad1/5/9 phosphorylation. In addition, Erk phosphorylation is increased independent of Fgf18 treatment indicating that both, HS and CS, affect growth factor signaling in chondrocytes in distinct manners.

Characterization of C. elegans Chondroitin Proteoglycans and Their Large Functional and Structural Heterogeneity; Evolutionary Aspects on Structural Differences Between Humans and the Nematode.

Proteoglycans regulate important cellular pathways in essentially all metazoan organisms. While considerable effort has been devoted to study structural and functional aspects of proteoglycans in vertebrates, the knowledge of the core proteins and proteoglycan-related functions in invertebrates is relatively scarce, even for C.elegans. This nematode produces a large amount of non-sulfated chondroitin in addition to small amount of low-sulfated chondroitin chains (Chn and CS chains, respectively). Until recently, 9 chondroitin core proteins (CPGs) had been identified in C.elegans, none of which showed any homology to vertebrate counterparts or to other invertebrate core proteins. By using a glycoproteomic approach, we recently characterized the chondroitin glycoproteome of C.elegans, resulting in the identification of 15 novel CPG core proteins in addition to the 9 previously established. Three of the novel core proteins displayed homology to human proteins, indicating that CPG and CSPG core proteins may be more conserved throughout evolution than previously perceived. Bioinformatic analysis of the primary amino acid sequences revealed that the core proteins contained a broad range of functional domains, indicating that specialization of proteoglycan-mediated functions may have evolved early in metazoan evolution. This review specifically discusses our recent data in relation to previous knowledge of core proteins and GAG-attachment sites in Chn and CS proteoglycans of C.elegans and humans, and point out both converging and diverging aspects of proteoglycan evolution.

The Effect of Simultaneous Radical Polymerization of Poly(N-vinyl pyrrolidone)/α,ω-Bis(methacryloyloxy-poly(ethylene glycol)) on Physical Properties of Marine Polysaccharide

In order to expand the application in biomedical field of bio-derived polymers it is imperative that the issues related to their surface properties be addressed. Here we explore the approach of simultaneous radical polymerization to modify the surface properties of chitosan by grafting/crosslinking with poly(N-vinyl pyrrolidone) (PNVP)/α,ω-bis (methacryloyloxy-poly(ethylene glycol) (M-PEG) in the presence of potassium persulfate. The structure of the resultant copolymer membranes was proved by Attenuated Total Reflectance-Fourier Transform Infrared Spectrometry. Scanning Electron Microscopy and Atomic Force Microscopy revealed the crosslinked copolymer membranes are porous materials with pore dimension, distribution and shape depending on the content of vinyl sequences. In addition, was revealed that the presence of vinyl crosslinked sequences linked to CS is disturbing the thermodynamic equilibrium conformation of CS. As a consequence, the ordering of CS chains into crystalline domains is reduced and the planes giving rise to the diffraction peaks are modified. Thus, the resultant copolymer membranes, depending by the weight ratio PNVP/M-PEG, became more amorphous. As a result of the crosslinking, the copolymer membranes were characterized by a smaller water swelling degree (about 300%) as compared with neat chitosan membrane (700%). The thermo-oxidative data have revealed an enhancement of the thermal stability of CS by crosslinking with PNVP/M-PEG copolymers. The water contact angles of the copolymer membranes proved to be more water wettable as compared to neat chitosan membrane.