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

Bachvarova, Velina; Dierker, Tabea; Hoffmann, Daniel; Kjellén, Lena; Vortkamp, Andrea

doi:10.1016/j.matbio.2020.03.006

Cited by 16 publications

(16 citation statements)

References 59 publications

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“…This is associated with and may likely cause elevated GAG-synthesis and GAG-deposition in HS-deficient cartilage. In line, data from Bachvarova et al indicate that Ext1 gt/gt chondrocytes compensate HS-deficiency by overproduction of chondroitin sulfate, likely attached to aggrecan, a major component of the articular cartilage [ 10 ]. Increased cartilage matrix formation also occurs in affected tissue of mouse mutants mimicking Hereditary Multiple Exostoses (HME), a disease linked to aberrant Ext1 -expression [ 51 , 52 , 53 ].…”

Section: Discussionmentioning

confidence: 72%

“…Ext1 gt/gt mice were bred by mating heterozygous Ext1 gt ( ext1 Gt(pGT2TMpfs)064Wcs ) mice that were maintained on a C57Bl/6 J background [ 37 ]. Genotyping was performed by genomic PCR of tail biopsies as described elsewhere [ 10 ].…”

Section: Methodsmentioning

confidence: 99%

“…Remarkably, already during early OA, chondrocytes fail to compensate for the loss of GAGs by enhanced synthesis [ 7 , 8 , 9 ]. Although the HS-content is 100 times lower than the CS-content in cartilage of porcine articular cartilage, an increasing number of studies suggest a role for HS in OA-development [ 10 , 11 , 12 , 13 , 14 ]. Reduction in HS-synthesizing ( EXT1 ) or modifying enzymes (NDST1) [ 12 ], deletion of the major HS-bearing proteoglycan Syndecan-4 (SDC4) [ 13 ], or ablation of the HS-modification of Perlecan (HSPG2) [ 14 ] resulted in chondro-protective effects in mouse models after surgical induction of OA.…”

Section: Introductionmentioning

confidence: 99%

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Heparan Sulfate Deficiency in Cartilage: Enhanced BMP-Sensitivity, Proteoglycan Production and an Anti-Apoptotic Expression Signature after Loading

Gerstner

Severmann

Chasan

et al. 2021

IJMS

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Osteoarthritis (OA) represents one major cause of disability worldwide still evading efficient pharmacological or cellular therapies. Severe degeneration of extracellular cartilage matrix precedes the loss of mobility and disabling pain perception in affected joints. Recent studies showed that a reduced heparan sulfate (HS) content protects cartilage from degradation in OA-animal models of joint destabilization but the underlying mechanisms remained unclear. We aimed to clarify whether low HS-content alters the mechano-response of chondrocytes and to uncover pathways relevant for HS-related chondro-protection in response to loading. Tissue-engineered cartilage with HS-deficiency was generated from rib chondrocytes of mice carrying a hypomorphic allele of Exostosin 1 (Ext1), one of the main HS-synthesizing enzymes, and wildtype (WT) littermate controls. Engineered cartilage matured for 2 weeks was exposed to cyclic unconfined compression in a bioreactor. The molecular loading response was determined by transcriptome profiling, bioinformatic data processing, and qPCR. HS-deficient chondrocytes expressed 3–6% of WT Ext1-mRNA levels. Both groups similarly raised Sox9, Col2a1, and Acan levels during maturation. However, HS-deficient chondrocytes synthesized and deposited 50% more GAG/DNA. TGFβ and FGF2-sensitivity of Ext1gt/gt chondrocytes was similar to WT cells but their response to BMP-stimulation was enhanced. Loading induced similar activation of mechano-sensitive ERK and P38-signaling in WT and HS-reduced chondrocytes. Transcriptome analysis reflected regulation of cell migration as major load-induced biological process with similar stimulation of common (Fosl1, Itgα5, Timp1, and Ngf) as well as novel mechano-regulated genes (Inhba and Dhrs9). Remarkably, only Ext1-hypomorphic cartilage responded to loading by an expression signature of negative regulation of apoptosis with pro-apoptotic Bnip3 being selectively down-regulated. HS-deficiency enhanced BMP-sensitivity, GAG-production and fostered an anti-apoptotic expression signature after loading, all of which may protect cartilage from load-induced erosion.

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Section: Discussionmentioning

confidence: 72%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Heparan Sulfate Deficiency in Cartilage: Enhanced BMP-Sensitivity, Proteoglycan Production and an Anti-Apoptotic Expression Signature after Loading

Gerstner

Severmann

Chasan

et al. 2021

IJMS

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“…Hybridization was performed as described previously (67). Immunofluorescence staining was performed with a rat-CD44 antibody (Invitrogen) as described previously (68).…”

Section: Transcriptome Analysismentioning

confidence: 99%

Epigenetic mechanisms mediating cell state transitions in chondrocytes

Wuelling

Neu

Thiesen

et al. 2020

Preprint

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Epigenetic modifications play critical roles in regulating cell lineage differentiation, but the epigenetic mechanisms guiding specific differentiation steps within a cell lineage have rarely been investigated. To decipher such mechanisms, we used the defined transition from proliferating (PC) into hypertrophic chondrocytes (HC) during endochondral ossification as a model. We established a map of activating and repressive histone modifications for each cell type. ChromHMM state transition analysis and Pareto-based integration of differential levels of mRNA and epigenetic marks revealed that differentiation associated gene repression is initiated by the addition of H3K27me3 to promoters still carrying substantial levels of activating marks. Moreover, the integrative analysis identified genes specifically expressed in cells undergoing the transition into hypertrophy. Investigation of enhancer profiles detected surprising differences in enhancer number, location, and transcription factor binding sites between the two closely related cell types. Furthermore, cell type-specific upregulation of gene expression was associated with a shift from low to high H3K27ac decoration. Pathway analysis identified PC-specific enhancers associated with chondrogenic genes, while HC-specific enhancers mainly control metabolic pathways linking epigenetic signature to biological functions.

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“…This phenomenon has also been documented in HS-deficient CHO-cells and in embryonic stem cells with altered HS production, and also in vivo in cartilage of mouse embryos with defective HS biosynthesis. 8,59–61 A similar increase in CS amounts was not seen in the ext2 mutant, and it was speculated that the “committed step,” glycosyltransferases adding GlcNAc for HS (Extl3) or GalNAc for CS biosynthesis, could be critical in determining HS and CS/DS amounts. The more severe cartilage phenotype of the ext2 than the extl3 mutant could be another explanation.…”

Section: Introductionmentioning

confidence: 95%

Heparan Sulfate Biosynthesis in Zebrafish

Filipek-Górniok

Habicher

Ledin

et al. 2020

J Histochem Cytochem.

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The biosynthesis of heparan sulfate (HS) proteoglycans occurs in the Golgi compartment of cells and will determine the sulfation pattern of HS chains, which in turn will have a large impact on the biological activity of the proteoglycans. Earlier studies in mice have demonstrated the importance of HS for embryonic development. In this review, the enzymes participating in zebrafish HS biosynthesis, along with a description of enzyme mutants available for functional studies, are presented. The consequences of the zebrafish genome duplication and maternal transcript contribution are briefly discussed as are the possibilities of CRISPR/Cas9 methodologies to use the zebrafish model system for studies of biosynthesis as well as proteoglycan biology.

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

Cited by 16 publications

References 59 publications

Heparan Sulfate Deficiency in Cartilage: Enhanced BMP-Sensitivity, Proteoglycan Production and an Anti-Apoptotic Expression Signature after Loading

Heparan Sulfate Deficiency in Cartilage: Enhanced BMP-Sensitivity, Proteoglycan Production and an Anti-Apoptotic Expression Signature after Loading

Epigenetic mechanisms mediating cell state transitions in chondrocytes

Heparan Sulfate Biosynthesis in Zebrafish

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