bims-supasi 2026-05-31 papers

bims-supasi

Biomed News

on Sulfation pathways and signalling

Issue of 2026–05–31
eleven papers selected by
Jonathan Wolf Mueller, University of Birmingham

Quantitative LC-MS/MS profiling reveals aberrant chondroitin sulfate in Alzheimer's disease.
Structural Characterization of Chondroitin Sulfate from Hybrid Sturgeon (Acipenser schrenckii × Huso dauricus) Cartilage and Its Alleviating Effect on Osteoarthritis.
Structural basis of chondroitin sulfate backbone polymer synthesis.
How pH and sulfation shape human heparanase structure, stability, and substrate recognition.
Gut-Derived Uremic Toxin Indoxyl Sulfate and Aryl Hydrocarbon Receptor in Renal Osteodystrophy.
Ext1-targeted gene therapy ameliorates tauopathy by inhibiting heparan sulfate-dependent tau propagation.
Fluorogenic Coupled Assays Reveal Catalytic Properties, Inhibition Constants and Cellular Location of Mucin-Active Carbohydrate Sulfatases.
Deciphering the role of chondroitin sulfate a in insulin fibrillation at room temperature: a biophysical and computational perspective.
Biomimetic injectable methacrylated chondroitin sulfate-collagen hydrogels enhance chondrocyte function and promote osteochondral regeneration.
Establishment of normal serum androgen levels in healthy Indian adolescent school-going girls by liquid chromatography-tandem mass spectrometry (LC-MS/MS).
Structural insights into interdomain interactions in Entamoeba histolytica APS kinase.

Commun Biol. 2026 May 28.

Quantitative LC-MS/MS profiling reveals aberrant chondroitin sulfate in Alzheimer's disease.

Yongmei Xu, Haoran Wang, Zhangjie Wang, Jianxiang Zhang, Eduardo Stancanelli, Qin Xu, Yiru Hou, Chunyu Wang, Peng Zhang, Marla Gearing, Jian Liu.

Chondroitin sulfate (CS) is an essential sulfated glycan in the brain, but standard LC-MS/MS disaccharide analysis provides only limited quantitative accuracy for detecting CS structural changes under physiological and pathophysiological conditions. Here, we incorporated eight distinct 13C-labeled CS disaccharide calibrants into the analytical workflow. Using this enhanced approach, we identified structural alterations in both sulfation patterns and total CS abundance in pre-clinical and clinical Alzheimer's disease (AD) brain samples compared with controls. Analysis of cerebrospinal fluid (CSF) from AD patients further revealed elevated levels of the CS-E disaccharide and reduced levels of hyaluronic acid. Functionally, we found that synthetic CS-E 19-mer-but not other synthetic CS 19-mer subtypes-impaired neuronal growth, underscoring the need to pinpoint specific CS structures that contribute to neurodegeneration. Because CS abnormalities are detectable in the pre-clinical AD brain, our findings raise the possibility that CS glycans could serve as early biomarkers for AD.

DOI: https://doi.org/10.1038/s42003-026-10358-x
Nutrients. 2026 May 08. pii: 1494. [Epub ahead of print]18(10):

Structural Characterization of Chondroitin Sulfate from Hybrid Sturgeon (Acipenser schrenckii × Huso dauricus) Cartilage and Its Alleviating Effect on Osteoarthritis.

Shanshan Zhang, Yanyan Li, Mingxiao Yu, Xue Zhao, Zeyu Liu, Tingting Yang, Changwei Wang, Hu Hou.

  Objectives: Given that the structure-activity relationship between sturgeon chondroitin sulfate (S-CS) and the alleviation of osteoarthritis (OA) remains unclear, we characterized the structure of S-CS and explored the relationship between its structure and its effect in alleviating OA. Methods: Chondroitin sulfate was extracted from sturgeon cartilage by alcohol precipitation. Its structure was thoroughly characterized using infrared spectroscopy, pre-column derivatization, high-performance liquid chromatography with PMP (PMP-HPLC), nuclear magnetic resonance spectroscopy (NMR), and other techniques. A rat OA model was established to explore the mechanism underlying its alleviation of OA. In addition, 16S rRNA sequencing was performed to investigate the role of gut microbiota. Results: S-CS was identified as a sulfated polysaccharide with an average molecular weight of 68.81 kDa and a GlcUA-to-GalN molar ratio of approximately 1:1. NMR analysis confirmed its characteristic 6-/4-sulfation patterns. Oral administration of S-CS at 100 mg/kg/d significantly alleviated joint damage by inhibiting the NF-κB and p38 MAPK signaling pathways. Specifically, S-CS decreased the levels of p65 and p38 by 18.94% and 52.40% (p < 0.05), respectively, and decreased TNF-α concentration. Moreover, 16S rRNA sequencing showed that S-CS enhanced the diversity and richness of gut microbiota and reconstructed the microbial community structure. Conclusions: S-CS may be an effective supplement for OA.

Keywords:  16S rRNA; NF-κB pathway; chondroitin sulfate from sturgeon cartilage (S-CS); p38 MAPK pathway; structure-activity relationship; sulfation pattern

DOI:  https://doi.org/10.3390/nu18101494
Nat Commun. 2026 May 27.

Structural basis of chondroitin sulfate backbone polymer synthesis.

Daniel Tehrani, Nil Cortiella-Valls, Chin Huang, Digantkumar Chapla, Zhifeng Zheng, Aarya Venkat, Brady O'Boyle, Natarajan Kannan, Camilo Perez, Kelley W Moremen.

Chondroitin sulfate (CS) proteoglycans are extended (-GlcAβ1,3GalNAcβ1,4-)n co-polymers attached to cell surface and extracellular matrix core proteins that are further modified by extensive sulfation and epimerization. Four homologous proteins contribute to CS backbone synthesis (CHPF1, CHPF2, CHSY1, and CHSY3) and prior data suggests assembly of the proteins into heterocomplexes is required for function. Here we show by sequence alignment and structural modeling that all CHSYs and CHPFs contain an N-terminal CAZy GT31-like domain and a C-terminal GT7-like domain separated by a cystatin-like linker domain. Co-expression of one CHPF and one CHSY is required to form a soluble, functional heterodimeric CS synthase and structural modeling indicates all four potential CHSY-CHPF combinations can form equivalent heterodimeric complexes. Cryo-EM studies on CHSY3-CHPF1 confirm the structure, interface, and active site features predicted by the structural models. Enzymatic analyses of catalytic mutants demonstrate that only the glycosyltransferase domains in the CHSYs are responsible for polymer synthesis: the GT31 domain transfers β1,3-GlcA while the GT7 domain transfers β1,4-GalNAc. The corresponding CHPF domains do not contribute to polymer synthesis but stabilize the corresponding CHSY functional domains. Additional mutagenesis and modeling suggest that the bridging cystatin-like domains may contribute to efficient polymer synthesis.

DOI: https://doi.org/10.1038/s41467-026-73361-0
Arch Biochem Biophys. 2026 May 27. pii: S0003-9861(26)00150-5. [Epub ahead of print]782 110879

How pH and sulfation shape human heparanase structure, stability, and substrate recognition.

Angela Pennacchio, Yesid Aristizabal, José Oñate-Garzón, Sabato D'Auria, Alessio Ausili.

  Human heparanase (HPSE) is an endo-β-d-glucuronidase involved in the degradation of heparan sulfate and in several physiopathological processes, including inflammation, metastasis, and extracellular matrix remodeling. Its activity is strongly influenced by pH and by the sulfation degree of the substrate, yet the structural bases underlying these effects remain only partially understood. In this work, we combine FTIR spectroscopy, temperature-dependent intrinsic fluorescence, and molecular dynamics (MD) simulation experiments to investigate the secondary structure, conformational stability, and structural determinants of substrate recognition in HPSE under different physicochemical conditions. FTIR analyses reveal pH-dependent variations in secondary structure, with acidic environments promoting a more compact and α-helix-rich conformation, consistent with the lysosomal conditions in which HPSE is physiologically active. Fluorescence experiments show a gradual unfolding process at all pH values, with maximal protein stability at pH 5.0. MD simulations of HPSE complexed with heparan-sulfate tetrasaccharides of different sulfation degrees indicate that ionic and hydrogen-bond interactions strongly contribute to binding affinity with highly sulfated ligands forming more stable and persistent interactions. Overall, the integration of spectroscopic analyses and computational simulations suggests that acidic pH and high substrate sulfation favor structural stability and ligand binding in HPSE, providing insights into the physicochemical factors regulating its activity.

Keywords:  Heparan sulfate (HS); Human heparanase (HPSE); Molecular dynamics simulations; Spectroscopic analysis (FTIR, fluorescence); pH-dependent thermostability

DOI:  https://doi.org/10.1016/j.abb.2026.110879
Biochimie. 2026 May 28. pii: S0300-9084(26)00118-5. [Epub ahead of print]

Gut-Derived Uremic Toxin Indoxyl Sulfate and Aryl Hydrocarbon Receptor in Renal Osteodystrophy.

Carl Ralph Russell, Neal Chen, Annabel Biruete, Matt Allen, Corinne Metzger, Joseph M Wallace, Sharon Moe.

  Chronic kidney disease (CKD) affects 14% individuals worldwide. Changes in bone and mineral metabolism in CKD are ubiquitous (CKD- Mineral and Bone Disorder) including renal osteodystrophy with a fracture incidence of up to 5 times greater than the general population. While PTH lowering is the mainstay of therapy for decades this has not reduced fractures in patients or improve bone mechanics in pre-clinical models. This suggests additional factors involved in the pathogenesis of renal osteodystrophy such as uremic toxins due to either increased production or decreased renal excretion. One group of toxins are metabolized by intestinal microbiota from tryptophan and include indoxyl sulfate, a potent ligand for the aryl hydrocarbon receptor (AhR) with downstream effect in many signaling pathways important in bone remodeling and metabolism. In AhR-/- mice, there is impaired fracture healing and mineralization by microCT, and we have shown in vitro that indoxyl sulfate activates AhR canonical signaling in osteocytes. This activation decreased osteocyte mineralization and alkaline phosphatase activity that were reversed by AhR receptor blocker. In early osteocytes, indoxyl sulfate also suppressed the RANKL/OPG ratio (receptor activator of nuclear factor kappa-Β ligand/osteoprotegrin), and increased Wnt inhibitor expression, changes that were reversed or blunted with AhR inhibitor and would reduce overall bone remodeling. Further, in a rat model of progressive CKD, we demonstrated that the dietary fiber inulin reduced indoxyl sulfate levels and improves renal osteodystrophy. These data suggest that the gut-derived uremic toxin indoxyl sulfate activates the AhR and adversely affects bone in CKD.

Keywords:  chronic kidney disease; fiber; indoxyl sulfate; microbiota; renal osteodystrophy

DOI:  https://doi.org/10.1016/j.biochi.2026.05.009
Pharmacol Res. 2026 May 28. pii: S1043-6618(26)00180-5. [Epub ahead of print]230 108265

Ext1-targeted gene therapy ameliorates tauopathy by inhibiting heparan sulfate-dependent tau propagation.

Rongyao Huang, Xiaoxun Ye, Jiayi Liu, Chunyan Yang, Xiaoya Meng, Tingting Dou, Xiaoqing Zhuang, Jinghan Yang, Naizhen Zheng, Yang Zhao, Zhongan Wang, Qin Wang, Jin Hu.

  The propagation of pathological tau protein in neuronal cells is a critical driver of neurodegeneration in tauopathies, including Alzheimer's disease. Heparan sulfate (HS) critically regulates pathological tau seeding and cellular uptake processes closely linked to the development of tau pathology in tauopathies, identifying HS as a key potential therapeutic target. Here, we focused on targeting Exostosin-1 (Ext1), an essential enzyme for HS biosynthesis, in the tauP301S transgenic (PS19) tauopathy mouse model. Conditional knockdown of neuronal Ext1 in PS19 mice by delivering an adeno-associated viral vector expressing Ext1 shRNA decreased neuronal HS levels, resulting in reduced pathological tau phosphorylation, enhanced synaptic function, and restored cognitive performance. Notably, decreasing neuronal Ext1 impeded the intercellular spread of human tau in the mouse brain. Furthermore, treating disease-onset PS19 mice with an antisense oligonucleotide targeting Ext1 ameliorated tau aggregation, improved behavioral deficits, and attenuated neurodegeneration and neuroinflammation. These results suggest that inhibiting tau propagation by targeting Ext1-mediated HS production could be a promising gene therapy approach for tauopathies.

Keywords:  Adeno-associated viral vector; Antisense oligonucleotide; Ext1; Heparan sulfate; Tau propagation; Tauopathies

DOI:  https://doi.org/10.1016/j.phrs.2026.108265
Angew Chem Int Ed Engl. 2026 May 23. e2991471

Fluorogenic Coupled Assays Reveal Catalytic Properties, Inhibition Constants and Cellular Location of Mucin-Active Carbohydrate Sulfatases.

Charles W E Tomlinson, Madouc D Bergers, David N Bolam, Ana S Luis, Alan Cartmell, Zachary Armstrong.

  Sulfated glycans play a central role in human health and influence cell signaling, cancer progression, pathogen invasion, and host-microbiome interactions. Metabolism of these glycans requires a specialized class of enzymes termed carbohydrate sulfatases. These enzymes are particularly important in the human gut where sulfated colonic mucin is produced and subsequently degraded by colonic bacteria. Despite the biological importance of carbohydrate sulfatases, there is currently a lack of chemical tools to study their activity, substrate selectivity, inhibition, and the discovery of novel enzymes. To address this, we have synthesized new chemical tools to rapidly and quantitatively determine the activity and selectivity of carbohydrate sulfatases in plate-based coupled assays. We have synthesized 3-O-sulfated fluorogenic glycosides using efficient synthetic routes and combined these fluorogenic substrates with a glycosidase that selectively cleaves unsulfated glycosides, allowing sensitive detection of sulfatase activity on both purified protein and cell lysate from the S1_20 subfamily sulfatases. Furthermore, we show that the assay enables differentiation and quantification of substrate specificity, identification of sulfatase inhibitors, and determination of sulfatase (sub-)cellular location for two S1_20 subfamily sulfatases. Collectively, we anticipate that these tools will further our understanding of the interplay between carbohydrate sulfatases, sulfated glycans, and human health.

Keywords:  biochemistry; carbohydrate; glycan; mucin; sialidase; sulfatase; sulfation

DOI:  https://doi.org/10.1002/anie.2991471
J Biomol Struct Dyn. 2026 May 24. 1-21

Deciphering the role of chondroitin sulfate a in insulin fibrillation at room temperature: a biophysical and computational perspective.

Malik Hisamuddin, Irum Rizvi, Ajamaluddin Malik, Javed Masood Khan, Syed Moasfar Ali, Tajalli Ilm Chandel, Nasif Hussain, Muhammad Uzair Ashraf, Rizwan Hasan Khan.

  Chondroitin sulfate A (CSA), a natural mucopolysaccharide of the extracellular matrix, plays a critical role in amyloidogenesis. This study explores the interaction between CSA and human insulin, with emphasis on conformational transitions and amyloid fibril formation. A combination of biophysical (UV-Vis spectroscopy, Far-UV CD, light scattering, ThT fluorescence), microscopic (TEM imaging), and computational approaches was employed to assess CSA's impact on insulin solubility, aggregation propensity, and structural rearrangements. Our findings reveal that CSA-induced amyloid formation proceeds through concentration-dependent aggregation of insulin. CSA exposure triggered dose-dependent aggregation of insulin, reaching saturation at a defined concentration. Light scattering increased linearly below 0.125 mg/mL CSA and plateaued thereafter. Far-UV CD analysis demonstrated a secondary structural transition from α-helical to cross-β-sheet above 0.125 mg/mL CSA, a hallmark of amyloid fibrils. ThT fluorescence kinetics and TEM imaging confirmed the presence of amyloid-like structures in CSA-treated insulin samples. Molecular docking identified a stable CSA binding site on the insulin surface mediated by hydrogen bonding and van der Waals interactions. Complementary molecular dynamics simulations suggest a possible structural basis by which CSA may influence insulin aggregation, demonstrating stable CSA binding and pH-dependent conformational changes in insulin over 200 ns. Collectively, these results establish CSA as an aggregation-promoting cofactor and highlight the utility of molecular simulations in dissecting amyloidogenic transitions. This work advances mechanistic understanding of glycosaminoglycan-mediated protein aggregation and offers insights relevant to pharmaceutical formulations and amyloid research.

Keywords:  Chondroitin sulfate A (CSA); ThT fluorescence kinetics; amyloid fibril; cross-β-sheet; human insulin

DOI:  https://doi.org/10.1080/07391102.2026.2664968
Biomater Sci. 2026 May 29.

Biomimetic injectable methacrylated chondroitin sulfate-collagen hydrogels enhance chondrocyte function and promote osteochondral regeneration.

Yining Yang, Yanni Li, Yu Zhang, Lujing Zhang, Kaisheng Wang, Xiaoyue Xu, Mengyao Li, Yan Yang, Yuankai Zhang.

The development of biomimetic scaffolds capable of promoting both cartilage and subchondral bone regeneration remains a major challenge in osteochondral tissue engineering. In this study, type I acid-soluble collagen (ASC) was successfully extracted from black flounder (Paralichthys olivaceus) skin and systematically characterized. The purified ASC retained its native triple-helical structure, as confirmed by SDS-PAGE, FTIR, CD, and XRD analyses, and exhibited favorable self-assembly behavior near physiological pH. Based on this natural matrix, photocrosslinkable methacrylated chondroitin sulfate (CSMA) was synthesized and combined with ASC or mineralized collagen (MC) to fabricate injectable composite hydrogels via UV-initiated polymerization. The resulting CSMA/COL and CSMA/MC hydrogels demonstrated tunable gelation times (90-120 s), high porosity, excellent swelling capacity, and superior mechanical strength (compressive modulus up to ∼40 kPa). Rheological analysis revealed stable viscoelastic properties with G' consistently exceeding G″. The composites also exhibited remarkable self-healing ability. In vitro, all hydrogel extracts displayed outstanding cytocompatibility, promoting primary chondrocyte adhesion, proliferation, and migration. Hydrogels containing collagen and MC (especially CS5M1) significantly enhanced the alkaline phosphatase (ALP) activity and upregulated chondrogenic gene expression (COL II, Acan, and Sox9). In vivo implantation in a rat full-thickness cartilage defect model demonstrated that CSMA-based composite hydrogels facilitated seamless defect filling, enhanced proteoglycan and glycosaminoglycan deposition, and promoted subchondral bone remodeling. Among all formulations, CS5M1 achieved the most complete repair, regenerating hyaline-like cartilage integrated with surrounding tissue after 12 weeks. Collectively, these results demonstrate that the composite hydrogels provide a biomimetic, injectable, and photo-curable platform with excellent osteochondral regenerative potential.

DOI: https://doi.org/10.1039/d6bm00316h
Endocrine. 2026 May 29. pii: 195. [Epub ahead of print]91(1):

Establishment of normal serum androgen levels in healthy Indian adolescent school-going girls by liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Rajni Sharma, Raman Kumar Marwaha, Ashutosh Kumar Arya, Konpal Paharia, Anwesha Saha, Priyanka Gupta, Himanshi Saini, Hem Chandra Sati.

   OBJECTIVE: The diagnosis of adolescent polycystic ovarian syndrome is based on the presence of menstrual irregularity and clinical/biochemical hyperandrogenism. However, the cut-off for normal adolescent androgen levels remains unclear. Normative data for androgens by LCMS for Indian adolescents is not available. We measured serum androgens by LCMS and DHEAS by immunoassay and their relation to the menstrual cycle phase and body mass index in healthy adolescent girls.
METHODS: This was a cross-sectional study in North India among girls studying in public schools. A total of 1469 girls aged 10-18 years were screened out of which 977 consented for blood sampling.
RESULTS: A total of 628 post-menarcheal with normal menstrual cycles and 142 premenarcheal girls were included. Normative data for serum testosterone, androstenedione, DHEA, DHEAS and DHT are presented as per post-menstrual (PMA) and chronological age. There was a progressive increase in levels of androgens with PMA with testosterone and androstenedione being significantly higher in the mid-cycle and luteal compared to the follicular phase. The upper reference limit (97.5th percentile [95% CI]) for testosterone in girls with post-menstrual age > 1 year in the follicular (n = 104), mid-cycle (n = 191) and luteal phase (n = 210) was 1.564 [1.431-1.698] nmol/l, 2.094 [1.90-2.77] nmol/l and 2.08 [1.837-2.166] nmol/l. Androstenedione and DHEAS levels were significantly higher in obese compared to normal weight girls whereas DHT levels were lower.
CONCLUSIONS: This study provides normative ethnicity-specific data for androgens using LCMS in Indian girls with normal menstrual cycles according to the post-menstrual age which can help define hyperandrogenaemia in adolescent girls and aid in the diagnosis of adolescent PCOS and ovarian/adrenal dysfunction irrespective of menstrual phase.

Keywords:  Androstenedione; DHEA; DHT; testosterone

DOI:  https://doi.org/10.1007/s12020-026-04668-7
J Struct Biol X. 2026 Jun;13 100147

Structural insights into interdomain interactions in Entamoeba histolytica APS kinase.

Ryo Hatanaka, Yukiko Ohsumi, Hiroki Matsui, Ayuna Inoguchi, Hina Yuasa, Fumika Mi-Ichi, Jun-Ichi Kishikawa, Tomoo Shiba.

  The biosynthetic pathway of 3'-phosphoadenosine-5'-phosphosulfate (PAPS) is a universal and essential metabolic process in many organisms, providing the activated sulfate donor required for the synthesis of diverse sulfated metabolites. However, this pathway has undergone substantial evolutionary diversification among species. In Entamoeba histolytica, PAPS biosynthesis occurs within the mitosomes, mitochondrion-related organelles (MROs), representing a distinctive example of lineage-specific evolutionary adaptation. PAPS synthesis proceeds through a conserved two-step process, which is sequentially catalyzed by ATP sulfurylase (AS) and adenosine 5'-phosphosulfate (APS) kinase (APSK). In this study, we focused on E. histolytica APSK (EhAPSK). EhAPSK contains an additional AS-like domain (SLD), although its functional role remains unclear. Here, we determined the crystal structure of full-length EhAPSK at 2.60 Å resolution and the structure of the truncated EhAPSK lacking APS kinase domain (KD) (EhAPSKΔKD) at 2.10 Å resolution. Structural analyses revealed that the SLD engages in dynamic contacts with the KD. Furthermore, deletion of the domain and mutational analyses indicated that the SLD significantly influences the catalytic activity of the KD. Based on these findings, we propose a new regulatory mechanism in which transient interdomain interactions modulate APS kinase activity, representing an unique evolutionary adaptation of E. histolytica.

Keywords:  Adenosine5′phosphosulfatekinase; Amoebiasis; Entamoeba histolytica; Single particle cryo-EM; Sulfate activation; X-ray crystallography

DOI:  https://doi.org/10.1016/j.yjsbx.2026.100147