Publications by authors named "John F Bateman"

84 Publications

Generation of a miR-26b stem-loop knockout human iPSC line, MCRIi019-A-1, using CRISPR/Cas9 editing.

Stem Cell Res 2020 Dec 10;50:102118. Epub 2020 Dec 10.

Murdoch Children's Research Institute, Parkville, Victoria, Australia; Department of Paediatrics, University of Melbourne, Australia. Electronic address:

miR-26b has been implicated in a wide range of human diseases, including cancer, diabetes, heart disease, Alzheimer's disease and osteoarthritis. To provide a tool to explore the importance of miR-26b in this broad context, we have generated and characterized a homozygous miR-26b stem-loop knockout human iPSC line. This gene-edited line exhibited a normal karyotype, expressed pluripotency markers and differentiated into cells representative of the three embryonic germ layers. This iPSC line will be valuable for studies investigating disease mechanisms and testing therapeutic strategies in vitro.
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http://dx.doi.org/10.1016/j.scr.2020.102118DOI Listing
December 2020

CRISPR/Cas9 editing to generate a heterozygous COL2A1 p.G1170S human chondrodysplasia iPSC line, MCRIi019-A-2, in a control iPSC line, MCRIi019-A.

Stem Cell Res 2020 10 6;48:101962. Epub 2020 Sep 6.

Murdoch Children's Research Institute, Australia; Department of Paediatrics, University of Melbourne, Australia.

To develop an in vitro disease model of a human chondrodysplasia, we used CRISPR/Cas9 gene editing to generate a heterozygous COL2A1 exon 50 c.3508 GGT > TCA (p.G1170S) mutation in a control human iPSC line. Both the control and COL2A1 mutant lines displayed typical iPSC characteristics, including normal cell morphology, expression of pluripotency markers, the ability to differentiate into endoderm, ectoderm and mesoderm lineages and normal karyotype. These chondrodysplasia mutant and isogenic control cell lines can be used to explore disease mechanisms underlying type II collagenopathies and aid in the discovery of new therapeutic strategies.
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http://dx.doi.org/10.1016/j.scr.2020.101962DOI Listing
October 2020

Identification of the skeletal progenitor cells forming osteophytes in osteoarthritis.

Ann Rheum Dis 2020 12 22;79(12):1625-1634. Epub 2020 Sep 22.

Arthritis and Regenerative Medicine Laboratory, Aberdeen Centre for Arthritis and Musculoskeletal Health, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK

Objectives: Osteophytes are highly prevalent in osteoarthritis (OA) and are associated with pain and functional disability. These pathological outgrowths of cartilage and bone typically form at the junction of articular cartilage, periosteum and synovium. The aim of this study was to identify the cells forming osteophytes in OA.

Methods: Fluorescent genetic cell-labelling and tracing mouse models were induced with tamoxifen to switch on reporter expression, as appropriate, followed by surgery to induce destabilisation of the medial meniscus. Contributions of fluorescently labelled cells to osteophytes after 2 or 8 weeks, and their molecular identity, were analysed by histology, immunofluorescence staining and RNA in situ hybridisation. mice and mice crossed with multicolour reporter mice were used for identification and clonal tracing of mesenchymal progenitors. Mice carrying , , , , or were crossed with tdTomato reporter mice to lineage-trace chondrocytes and stem/progenitor cell subpopulations.

Results: Articular chondrocytes, or skeletal stem cells identified by , or expression, did not give rise to osteophytes. Instead, osteophytes derived from -expressing stem/progenitor cells in periosteum and synovium that are descendants from the -expressing embryonic joint interzone. Further, we show that -expressing progenitors in periosteum supplied hybrid skeletal cells to the early osteophyte, while -expressing progenitors from synovial lining contributed to cartilage capping the osteophyte, but not to bone.

Conclusion: Our findings reveal distinct periosteal and synovial skeletal progenitors that cooperate to form osteophytes in OA. These cell populations could be targeted in disease modification for treatment of OA.
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http://dx.doi.org/10.1136/annrheumdis-2020-218350DOI Listing
December 2020

CRISPR/Cas9 gene editing of a SOX9 reporter human iPSC line to produce two TRPV4 patient heterozygous missense mutant iPSC lines, MCRIi001-A-3 (TRPV4 p.F273L) and MCRIi001-A-4 (TRPV4 p.P799L).

Stem Cell Res 2020 10 3;48:101942. Epub 2020 Aug 3.

Murdoch Children's Research Institute, Australia; Department of Paediatrics, University of Melbourne, Australia.

To produce in vitro models of human chondrodysplasias caused by dominant missense mutations in TRPV4, we used CRISPR/Cas9 gene editing to introduce two heterozygous patient mutations (p.F273L and p.P799L) into an established control human iPSC line. This control line expressed a fluorescent reporter (tdTomato) at the SOX9 locus to allow real-time monitoring of cartilage differentiation by SOX9 expression. Both TRPV4 mutant iPSC lines had normal karyotypes, expressed pluripotency markers, and could differentiate into cells representative of the three embryonic germ layers. These iPSC lines, with the parental isogenic control, will be used to study TRPV4 chondrodysplasia mechanisms and explore therapeutic approaches.
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http://dx.doi.org/10.1016/j.scr.2020.101942DOI Listing
October 2020

Generation of a heterozygous COL2A1 (p.R989C) spondyloepiphyseal dysplasia congenita mutation iPSC line, MCRIi001-B, using CRISPR/Cas9 gene editing.

Stem Cell Res 2020 05 11;45:101843. Epub 2020 May 11.

Murdoch Children's Research Institute, Australia; Department of Paediatrics, University of Melbourne, Australia.

To produce an in vitro model of the human chondrodysplasia, spondyloepiphyseal dysplasia congenita, we used CRISPR/Cas9 gene editing to generate a heterozygous patient COL2A1 mutation in an established control human iPSC line. The gene-edited heterozygous COL2A1 p.R989C line had a normal karyotype, expressed pluripotency markers, and could differentiate into cells representative of the three embryonic germ layers. When differentiated into cartilage this cell line and the parental isogenic control may be used to explore disease mechanisms and evaluate therapeutic approaches.
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http://dx.doi.org/10.1016/j.scr.2020.101843DOI Listing
May 2020

Generation of a SOX9-tdTomato reporter human iPSC line, MCRIi001-A-2, using CRISPR/Cas9 editing.

Stem Cell Res 2020 01 19;42:101689. Epub 2019 Dec 19.

Murdoch Children's Research Institute, Australia; Department of Paediatrics, University of Melbourne, Australia.

To develop an iPSC SOX9 reporter line for monitoring differentiation into SOX9 expressing cells such as chondrocytes, cranial neural crest and Sertoli cells, we used gene editing to introduce sequences encoding the tdTomato fluorescent protein into the SOX9 locus. The gene-edited line had a normal karyotype, expressed pluripotency markers and differentiated into cells representative of the three embryonic germ layers. Endogenous SOX9 expression was undisturbed and the tdTomato fluorescent reporter mirrored SOX9 mRNA expression. This iPSC line will be useful for assessing iPSC differentiation into SOX9-expressing cells and enrichment by cell sorting.
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http://dx.doi.org/10.1016/j.scr.2019.101689DOI Listing
January 2020

Identification of Two Independent Variants in Dogs with Ehlers-Danlos Syndrome.

Genes (Basel) 2019 09 21;10(10). Epub 2019 Sep 21.

Murdoch Children's Research Institute, Parkville, Victoria 3052, Australia.

The Ehlers-Danlos syndromes (EDS) are a heterogeneous group of heritable disorders affecting connective tissues. The mutations causing the various forms of EDS in humans are well characterized, but the genetic mutations causing EDS-like clinical pathology in dogs are not known, thus hampering accurate clinical diagnosis. Clinical analysis of two independent cases of skin hyperextensibility and fragility, one with pronounced joint hypermobility was suggestive of EDS. Whole-genome sequencing revealed de novo mutations of in both cases, confirming the diagnosis of the classical form of EDS. The heterozygous p.Gly1013ValfsTer260 mutation characterized in case 1 introduced a premature termination codon and would be expected to result in α1(V) mRNA nonsense-mediated mRNA decay and collagen V haploinsufficiency. While mRNA was not available from this dog, ultrastructural analysis of the dermis demonstrated variability in collagen fibril diameter and the presence of collagen aggregates, termed 'collagen cauliflowers', consistent with mutations underlying classical EDS. In the second case, DNA sequencing demonstrated a p.Gly1571Arg missense variant in the gene. While samples were not available for further analysis, such a glycine substitution would be expected to destabilize the strict molecular structure of the collagen V triple helix and thus affect protein stability and/or integration of the mutant collagen into the collagen V/collagen I heterotypic dermal fibrils. This is the first report of genetic variants in the gene causing the clinical presentation of EDS in dogs. These data provided further evidence of the important role of collagen V in dermal collagen fibrillogenesis. Importantly, from the clinical perspective, we showed the utility of DNA sequencing, combined with the established clinical criteria, in the accurate diagnosis of EDS in dogs.
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http://dx.doi.org/10.3390/genes10100731DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6826881PMC
September 2019

Cartilage endoplasmic reticulum stress may influence the onset but not the progression of experimental osteoarthritis.

Arthritis Res Ther 2019 09 11;21(1):206. Epub 2019 Sep 11.

Wellcome Trust Centre for Cell-Matrix Research, Faculty of Biology, Medicine and Health and Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PT, UK.

Background: Osteoarthritis has been associated with a plethora of pathological factors and one which has recently emerged is chondrocyte endoplasmic reticulum (ER) stress. ER stress is sensed by key ER-resident stress sensors, one of which is activating transcription factor 6 (ATF6). The purpose of this study is to determine whether increased ER stress plays a role in OA.

Methods: OA was induced in male wild-type (+/+), ColIITg (c/c) and Atf6α mice by destabilisation of the medial meniscus (DMM). c/c mice have increased ER stress in chondrocytes via the collagen II promoter-driven expression of ER stress-inducing Tg. Knee joints were scored histologically for OA severity. RNA-seq was performed on laser-micro-dissected RNA from cartilage of +/+ and c/c DMM-operated mice.

Results: In situ hybridisation demonstrated a correlation between the upregulation of ER stress marker, BiP, and early signs of proteoglycan loss and cartilage damage in DMM-operated +/+ mice. Histological analysis revealed a significant reduction in OA severity in c/c mice compared with +/+ at 2 weeks post-DMM. This chondroprotective effect in c/c mice was associated with a higher ambient level of BiP protein prior to DMM and a delay in chondrocyte apoptosis. RNA-seq analysis suggested Xbp1-regulated networks to be significantly enriched in c/c mice at 2 weeks post-DMM. Compromising the ER through genetically ablating Atf6α, a key ER stress sensor, had no effect on DMM-induced OA severity.

Conclusion: Our studies indicate that an increased capacity to effectively manage increases in ER stress in articular cartilage due either to pre-conditioning as a result of prior exposure to ER stress or to genetic pre-disposition may be beneficial in delaying the onset of OA, but once established, ER stress plays no significant role in disease progression.
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http://dx.doi.org/10.1186/s13075-019-1988-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6737683PMC
September 2019

XBP1 signalling is essential for alleviating mutant protein aggregation in ER-stress related skeletal disease.

PLoS Genet 2019 07 1;15(7):e1008215. Epub 2019 Jul 1.

Institute of Genetic Medicine, Newcastle University, Newcastle, United Kingdom.

The unfolded protein response (UPR) is a conserved cellular response to the accumulation of proteinaceous material in endoplasmic reticulum (ER), active both in health and disease to alleviate cellular stress and improve protein folding. Multiple epiphyseal dysplasia (EDM5) is a genetic skeletal condition and a classic example of an intracellular protein aggregation disease, whereby mutant matrilin-3 forms large insoluble aggregates in the ER lumen, resulting in a specific 'disease signature' of increased expression of chaperones and foldases, and alternative splicing of the UPR effector XBP1. Matrilin-3 is expressed exclusively by chondrocytes thereby making EDM5 a perfect model system to study the role of protein aggregation in disease. In order to dissect the role of XBP1 signalling in aggregation-related conditions we crossed a p.V194D Matn3 knock-in mouse model of EDM5 with a mouse line carrying a cartilage specific deletion of XBP1 and analysed the resulting phenotype. Interestingly, the growth of mice carrying the Matn3 p.V194D mutation compounded with the cartilage specific deletion of XBP1 was severely retarded. Further phenotyping revealed increased intracellular retention of amyloid-like aggregates of mutant matrilin-3 coupled with dramatically decreased cell proliferation and increased apoptosis, suggesting a role of XBP1 signalling in protein accumulation and/or degradation. Transcriptomic analysis of chondrocytes extracted from wild type, EDM5, Xbp1-null and compound mutant lines revealed that the alternative splicing of Xbp1 is crucial in modulating levels of protein aggregation. Moreover, through detailed transcriptomic comparison with a model of metaphyseal chondrodysplasia type Schmid (MCDS), an UPR-related skeletal condition in which XBP1 was removed without overt consequences, we show for the first time that the differentiation-state of cells within the cartilage growth plate influences the UPR resulting from retention of a misfolded mutant protein and postulate that modulation of XBP1 signalling pathway presents a therapeutic target for aggregation related conditions in cells undergoing proliferation.
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http://dx.doi.org/10.1371/journal.pgen.1008215DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6625722PMC
July 2019

Extra-skeletal manifestations in mice affected by -dependent autosomal dominant osteopetrosis type 2 clinical and therapeutic implications.

Bone Res 2019 11;7:17. Epub 2019 Jun 11.

1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy.

Autosomal dominant osteopetrosis type 2 (ADO2) is a high-density brittle bone disease characterized by bone pain, multiple fractures and skeletal-related events, including nerve compression syndrome and hematological failure. We demonstrated that in mice carrying the heterozygous mutation, whose human mutant homolog affects patients, the clinical impacts of ADO2 extend beyond the skeleton, affecting several other organs. The hallmark of the extra-skeletal alterations is a consistent perivascular fibrosis, associated with high numbers of macrophages and lymphoid infiltrates. Fragmented clinical information in a small cohort of patients confirms extra-skeletal alterations consistent with a systemic disease, in line with the observation that the gene is expressed in many organs. ADO2 mice also show anxiety and depression and their brains exhibit not only perivascular fibrosis but also β-amyloid accumulation and astrogliosis, suggesting the involvement of the nervous system in the pathogenesis of the ADO2 extra-skeletal alterations. Extra-skeletal organs share a similar cellular pathology, confirmed also in vitro in bone marrow mononuclear cells and osteoclasts, characterized by an impairment of the exit pathway of the protein product, ClC7, through the Golgi, with consequent reduced ClC7 expression in late endosomes and lysosomes, associated with high vesicular pH and accumulation of autophagosome markers. Finally, an experimental siRNA therapy, previously proven to counteract the bone phenotype, also improves the extra-skeletal alterations. These results could have important clinical implications, supporting the notion that a systematic evaluation of ADO2 patients for extra-skeletal symptoms could help improve their diagnosis, clinical management, and therapeutic options.
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http://dx.doi.org/10.1038/s41413-019-0055-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6559989PMC
June 2019

The use of simultaneous reprogramming and gene correction to generate an osteogenesis imperfecta patient COL1A1 c. 3936 G>T iPSC line and an isogenic control iPSC line.

Stem Cell Res 2019 07 4;38:101453. Epub 2019 May 4.

Murdoch Children's Research Institute, Australia; Department of Biochemistry and Molecular Biology, University of Melbourne, Australia. Electronic address:

To develop a disease model for the human 'brittle bone' disease, osteogenesis imperfecta, we used a simultaneous reprogramming and CRISPR-Cas9 genome editing method to produce an iPSC line with the heterozygous patient mutation (COL1A1 c. 3936 G>T) along with an isogenic gene-corrected control iPSC line. Both IPSC lines had a normal karyotype, expressed pluripotency markers and differentiated into cells representative of the three embryonic germ layers. This osteogenesis imperfecta mutant and isogenic iPSC control line will be of use in exploring disease mechanisms and therapeutic approaches in vitro.
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http://dx.doi.org/10.1016/j.scr.2019.101453DOI Listing
July 2019

Generation of a heterozygous COL1A1 (c.3969_3970insT) osteogenesis imperfecta mutation human iPSC line, MCRIi001-A-1, using CRISPR/Cas9 editing.

Stem Cell Res 2019 05 23;37:101449. Epub 2019 Apr 23.

Murdoch Children's Research Institute, University of Melbourne, Australia; Department of Biochemistry and Molecular Biology, University of Melbourne, Australia. Electronic address:

To develop a disease model for the human 'brittle bone' disease, osteogenesis imperfecta, we have used gene editing to produce a facsimile of the patient heterozygous COL1A1 mutation in an established control iPSC line. The gene-edited line had a normal karyotype, expressed pluripotency markers and differentiated into cells representative of the three embryonic germ layers. This iPSC line and the isogenic parental iPSC line will be of use in exploring osteogenesis imperfecta disease mechanisms and therapeutic approaches in vitro.
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http://dx.doi.org/10.1016/j.scr.2019.101449DOI Listing
May 2019

Genetic Disorders of the Extracellular Matrix.

Anat Rec (Hoboken) 2020 06 6;303(6):1527-1542. Epub 2019 Mar 6.

Musculoskeletal Research, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville Victoria, Australia.

Mutations in the genes for extracellular matrix (ECM) components cause a wide range of genetic connective tissues disorders throughout the body. The elucidation of mutations and their correlation with pathology has been instrumental in understanding the roles of many ECM components. The pathological consequences of ECM protein mutations depend on its tissue distribution, tissue function, and on the nature of the mutation. The prevalent paradigm for the molecular pathology has been that there are two global mechanisms. First, mutations that reduce the production of ECM proteins impair matrix integrity largely due to quantitative ECM defects. Second, mutations altering protein structure may reduce protein secretion but also introduce dominant negative effects in ECM formation, structure and/or stability. Recent studies show that endoplasmic reticulum (ER) stress, caused by mutant misfolded ECM proteins, makes a significant contribution to the pathophysiology. This suggests that targeting ER-stress may offer a new therapeutic strategy in a range of ECM disorders caused by protein misfolding mutations. Anat Rec, 2019. © 2019 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.
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http://dx.doi.org/10.1002/ar.24086DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7318566PMC
June 2020

Effect of rapamycin on bone mass and strength in the α2(I)-G610C mouse model of osteogenesis imperfecta.

J Cell Mol Med 2019 03 30;23(3):1735-1745. Epub 2018 Dec 30.

Orthopaedic Research and Biotechnology Unit, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.

Osteogenesis imperfecta (OI) is commonly caused by heterozygous type I collagen structural mutations that disturb triple helix folding and integrity. This mutant-containing misfolded collagen accumulates in the endoplasmic reticulum (ER) and induces a form of ER stress associated with negative effects on osteoblast differentiation and maturation. Therapeutic induction of autophagy to degrade the mutant collagens could therefore be useful in ameliorating the ER stress and deleterious downstream consequences. To test this, we treated a mouse model of mild to moderate OI (α2(I) G610C) with dietary rapamycin from 3 to 8 weeks of age and effects on bone mass and mechanical properties were determined. OI bone mass and mechanics were, as previously reported, compromised compared to WT. While rapamycin treatment improved the trabecular parameters of WT and OI bones, the biomechanical deficits of OI bones were not rescued. Importantly, we show that rapamycin treatment suppressed the longitudinal and transverse growth of OI, but not WT, long bones. Our work demonstrates that dietary rapamycin offers no clinical benefit in this OI model and furthermore, the impact of rapamycin on OI bone growth could exacerbate the clinical consequences during periods of active bone growth in patients with OI caused by collagen misfolding mutations.
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http://dx.doi.org/10.1111/jcmm.14072DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6378195PMC
March 2019

Identification of TGFβ-related genes regulated in murine osteoarthritis and chondrocyte hypertrophy by comparison of multiple microarray datasets.

Bone 2018 11 21;116:67-77. Epub 2018 Jul 21.

Department of Orthopedics, Erasmus MC University Medical Center, Rotterdam, the Netherlands; Department of Otorhinolaryngology, Erasmus MC University Medical Center, Rotterdam, the Netherlands. Electronic address:

Objective: Osteoarthritis (OA) is a joint disease characterized by progressive degeneration of articular cartilage. Some features of OA, including chondrocyte hypertrophy and focal calcification of articular cartilage, resemble the endochondral ossification processes. Alterations in transforming growth factor β (TGFβ) signaling have been associated with OA as well as with chondrocyte hypertrophy. Our aim was to identify novel candidate genes implicated in chondrocyte hypertrophy during OA pathogenesis by determining which TGFβ-related genes are regulated during murine OA and endochondral ossification.

Methods: A list of 580 TGFβ-related genes, including TGFβ signaling pathway components and TGFβ-target genes, was generated. Regulation of these TGFβ-related genes was assessed in a microarray of murine OA cartilage: 1, 2 and 6 weeks after destabilization of the medial meniscus (DMM). Subsequently, genes regulated in the DMM model were studied in two independent murine microarray datasets on endochondral ossification: the growth plate and transient embryonic cartilage (joint development).

Results: A total of 106 TGFβ-related genes were differentially expressed in articular cartilage of DMM-operated mice compared to sham-control. From these genes, 43 were similarly regulated during chondrocyte hypertrophy in the growth plate or embryonic joint development. Among these 43 genes, 18 genes have already been associated with OA. The remaining 25 genes were considered as novel candidate genes involved in OA pathogenesis and endochondral ossification. In supplementary data of published human OA microarrays we found indications that 15 of the 25 novel genes are indeed regulated in articular cartilage of human OA patients.

Conclusion: By focusing on TGFβ-related genes during OA and chondrocyte hypertrophy in mice, we identified 18 known and 25 new candidate genes potentially implicated in phenotypical changes in chondrocytes leading to OA. We propose that 15 of these candidates warrant further investigation as therapeutic target for OA as they are also regulated in articular cartilage of OA patients.
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http://dx.doi.org/10.1016/j.bone.2018.07.008DOI Listing
November 2018

Collagen VI disorders: Insights on form and function in the extracellular matrix and beyond.

Matrix Biol 2018 10 22;71-72:348-367. Epub 2017 Dec 22.

Musculoskeletal Research, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Vic, Australia; Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Vic, Australia.

Mutations in the three canonical collagen VI genes, COL6A1, COL6A2 and COL6A3, cause a spectrum of muscle disease from Bethlem myopathy at the mild end to the severe Ullrich congenital muscular dystrophy. Mutations can be either dominant or recessive and the resulting clinical severity is influenced by the way mutations impact the complex collagen VI assembly process. Most mutations are found towards the N-terminus of the triple helical collagenous domain and compromise extracellular microfibril assembly. Outside the triple helix collagen VI is highly polymorphic and discriminating mutations from rare benign changes remains a major diagnostic challenge. Collagen VI deficiency alters extracellular matrix structure and biomechanical properties and leads to increased apoptosis and oxidative stress, decreased autophagy, and impaired muscle regeneration. Therapies that target these downstream consequences have been tested in a collagen VI null mouse and also in small human trials where they show modest clinical efficacy. An important role for collagen VI in obesity, cancer and diabetes is emerging. A major barrier to developing effective therapies is the paucity of information about how collagen VI deficiency in the extracellular matrix signals the final downstream consequences - the receptors involved and the intracellular messengers await further characterization.
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http://dx.doi.org/10.1016/j.matbio.2017.12.008DOI Listing
October 2018

Comprehensive Expression Analysis of microRNAs and mRNAs in Synovial Tissue from a Mouse Model of Early Post-Traumatic Osteoarthritis.

Sci Rep 2017 12 18;7(1):17701. Epub 2017 Dec 18.

Murdoch Childrens Research Institute, Parkville, Victoria, 3052, Australia.

To better understand the molecular processes involved in driving osteoarthritis disease progression we characterized expression profiles of microRNAs (miRNA) and mRNAs in synovial tissue from a post-traumatic OA mouse model. OA was induced in 10-12 week old male C57BL6 mice by bilateral surgical destabilization of the medial meniscus (DMM). RNA isolated from the anterior synovium of mice at 1 and 6 weeks post-surgery was subject to expression profiling using Agilent microarrays and qPCR. OA severity was determined histologically. Anterior and posterior synovitis decreased with post-operative time after sham and DMM. No differences in synovitis parameters were evident between sham and DMM in the anterior synovium at either time. While expression profiling revealed 394 miRNAs were dysregulated between 1 and 6 week time-points in the anterior synovium, there were no significant changes in miRNA or mRNA expression between DMM and sham mice at both time-points. Bioinformatic analysis of the miRNAs and mRNAs differentially expressed in tandem with the resolution of anterior synovial inflammation revealed similar biological processes and functions, including organismal injury, connective tissue disorder and inflammatory responses. Our data demonstrates that early OA-specific patterns of synovial miRNAs or mRNAs dysregulation could not be identified in this model of post-traumatic OA.
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http://dx.doi.org/10.1038/s41598-017-17545-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5735155PMC
December 2017

Cartilage MicroRNA Dysregulation During the Onset and Progression of Mouse Osteoarthritis Is Independent of Aggrecanolysis and Overlaps With Candidates From End-Stage Human Disease.

Arthritis Rheumatol 2018 03 6;70(3):383-395. Epub 2018 Feb 6.

Murdoch Children's Research Institute and University of Melbourne, Parkville, Victoria, Australia.

Objective: To identify candidate microRNAs (miRNAs) that potentially regulate the initiation and progression of osteoarthritis (OA).

Methods: OA was induced in 10-12-week-old male wild-type C57BL/6 mice and in mice resistant to aggrecanase cleavage (Acan p.374ALGS→374NVYS) by destabilization of the medial meniscus (DMM). Pathologic changes of OA were scored histologically. RNA from cartilage and subchondral bone was harvested in parallel by laser microdissection at 1 week and 6 weeks postsurgery. Global miRNA expression profiling was performed using Agilent microarrays and was validated by quantitative polymerase chain reaction analysis.

Results: Wild-type DMM mice had characteristic cartilage degeneration, subchondral bone sclerosis, and osteophyte formation. While no miRNA dysregulation was seen in subchondral bone, 139 miRNAs were differentially expressed in cartilage obtained at 1 and/or 6 weeks after OA initiation from wild-type mice that underwent DMM. To prioritize OA candidates, dysregulated miRNAs with human orthologs were filtered, and paired miRNA/messenger RNA (mRNA) expression analysis was conducted to identify those with corresponding changes in mRNA target transcripts in the DMM mouse cartilage. An important cohort also overlapped with miRNAs identified in human end-stage OA. Comparisons of miRNA dysregulation in DMM mouse cartilage where aggrecan cleavage was genetically ablated demonstrated that all candidates were independent of aggrecan breakdown, earmarking these as important to the critical stages of OA initiation. Furthermore, functional enrichment analysis and data annotation revealed the responses to mechanical stimuli, apoptotic processes, and core extracellular matrix structural and regulatory factors to be potentially influenced by OA-dysregulated miRNA/mRNA networks.

Conclusion: Our comprehensive analyses identified high-priority miRNA candidates that have potential as biomarkers and therapeutic targets in human OA.
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http://dx.doi.org/10.1002/art.40378DOI Listing
March 2018

Increased intracellular proteolysis reduces disease severity in an ER stress-associated dwarfism.

J Clin Invest 2017 Oct 18;127(10):3861-3865. Epub 2017 Sep 18.

Wellcome Trust Centre for Cell-Matrix Research.

The short-limbed dwarfism metaphyseal chondrodysplasia type Schmid (MCDS) is linked to mutations in type X collagen, which increase ER stress by inducing misfolding of the mutant protein and subsequently disrupting hypertrophic chondrocyte differentiation. Here, we show that carbamazepine (CBZ), an autophagy-stimulating drug that is clinically approved for the treatment of seizures and bipolar disease, reduced the ER stress induced by 4 different MCDS-causing mutant forms of collagen X in human cell culture. Depending on the nature of the mutation, CBZ application stimulated proteolysis of misfolded collagen X by either autophagy or proteasomal degradation, thereby reducing intracellular accumulation of mutant collagen. In MCDS mice expressing the Col10a1.pN617K mutation, CBZ reduced the MCDS-associated expansion of the growth plate hypertrophic zone, attenuated enhanced expression of ER stress markers such as Bip and Atf4, increased bone growth, and reduced skeletal dysplasia. CBZ produced these beneficial effects by reducing the MCDS-associated abnormalities in hypertrophic chondrocyte differentiation. Stimulation of intracellular proteolysis using CBZ treatment may therefore be a clinically viable way of treating the ER stress-associated dwarfism MCDS.
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http://dx.doi.org/10.1172/JCI93094DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5617653PMC
October 2017

The intervertebral disc contains intrinsic circadian clocks that are regulated by age and cytokines and linked to degeneration.

Ann Rheum Dis 2017 Mar 3;76(3):576-584. Epub 2016 Aug 3.

Faculty of Life Sciences, University of Manchester, Manchester, UK.

Objectives: The circadian clocks are internal timing mechanisms that drive ∼24-hour rhythms in a tissue-specific manner. Many aspects of the physiology of the intervertebral disc (IVD) show clear diurnal rhythms. However, it is unknown whether IVD tissue contains functional circadian clocks and if so, how their dysregulation is implicated in IVD degeneration.

Methods: Clock gene dynamics in ex vivo IVD explants (from PER2:: luciferase (LUC) reporter mice) and human disc cells (transduced with lentivirus containing ::luc reporters) were monitored in real time by bioluminescence photon counting and imaging. Temporal gene expression changes were studied by RNAseq and quantitative reverse transcription (qRT)-PCR. IVD pathology was evaluated by histology in a mouse model with tissue-specific deletion of the core clock gene .

Results: Here we show the existence of the circadian rhythm in mouse IVD tissue and human disc cells. This rhythm is dampened with ageing in mice and can be abolished by treatment with interleukin-1β but not tumour necrosis factor α. Time-series RNAseq revealed 607 genes with 24-hour patterns of expression representing several essential pathways in IVD physiology. Mice with conditional knockout of in their disc cells demonstrated age-related degeneration of IVDs.

Conclusions: We have established autonomous circadian clocks in mouse and human IVD cells which respond to age and cytokines, and control key pathways involved in the homeostasis of IVDs. Genetic disruption to the mouse IVD molecular clock predisposes to IVD degeneration. These results support the concept that disruptions to circadian rhythms may be a risk factor for degenerative IVD disease and low back pain.
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http://dx.doi.org/10.1136/annrheumdis-2016-209428DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5446006PMC
March 2017

Novel Elements of the Chondrocyte Stress Response Identified Using an in Vitro Model of Mouse Cartilage Degradation.

J Proteome Res 2016 Mar 12;15(3):1033-50. Epub 2016 Feb 12.

Murdoch Childrens Research Institute, Royal Children's Hospital , Parkville, Melbourne, Victoria 3052, Australia.

The destruction of articular cartilage in osteoarthritis involves chondrocyte dysfunction and imbalanced extracellular matrix (ECM) homeostasis. Pro-inflammatory cytokines such as interleukin-1α (IL-1α) contribute to osteoarthritis pathophysiology, but the effects of IL-1α on chondrocytes within their tissue microenvironment have not been fully evaluated. To redress this we used label-free quantitative proteomics to analyze the chondrocyte response to IL-1α within a native cartilage ECM. Mouse femoral heads were cultured with and without IL-1α, and both the tissue proteome and proteins released into the media were analyzed. New elements of the chondrocyte response to IL-1α related to cellular stress included markers for protein misfolding (Armet, Creld2, and Hyou1), enzymes involved in glutathione biosynthesis and regeneration (Gstp1, Gsto1, and Gsr), and oxidative stress proteins (Prdx2, Txn, Atox1, Hmox1, and Vnn1). Other proteins previously not associated with the IL-1α response in cartilage included ECM components (Smoc2, Kera, and Crispld1) and cysteine proteases (cathepsin Z and legumain), while chondroadherin and cartilage-derived C-type lectin (Clec3a) were identified as novel products of IL-1α-induced cartilage degradation. This first proteome-level view of the cartilage IL-1α response identified candidate biomarkers of cartilage destruction and novel targets for therapeutic intervention in osteoarthritis.
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http://dx.doi.org/10.1021/acs.jproteome.5b01115DOI Listing
March 2016

XBP1-Independent UPR Pathways Suppress C/EBP-β Mediated Chondrocyte Differentiation in ER-Stress Related Skeletal Disease.

PLoS Genet 2015 Sep 15;11(9):e1005505. Epub 2015 Sep 15.

Murdoch Childrens Research Institute, Parkville, Victoria, Australia; Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia.

Schmid metaphyseal chondrodysplasia (MCDS) involves dwarfism and growth plate cartilage hypertrophic zone expansion resulting from dominant mutations in the hypertrophic zone collagen, Col10a1. Mouse models phenocopying MCDS through the expression of an exogenous misfolding protein in the endoplasmic reticulum (ER) in hypertrophic chondrocytes have demonstrated the central importance of ER stress in the pathology of MCDS. The resultant unfolded protein response (UPR) in affected chondrocytes involved activation of canonical ER stress sensors, IRE1, ATF6, and PERK with the downstream effect of disrupted chondrocyte differentiation. Here, we investigated the role of the highly conserved IRE1/XBP1 pathway in the pathology of MCDS. Mice with a MCDS collagen X p.N617K knock-in mutation (ColXN617K) were crossed with mice in which Xbp1 was inactivated specifically in cartilage (Xbp1CartΔEx2), generating the compound mutant, C/X. The severity of dwarfism and hypertrophic zone expansion in C/X did not differ significantly from ColXN617K, revealing surprising redundancy for the IRE1/XBP1 UPR pathway in the pathology of MCDS. Transcriptomic analyses of hypertrophic zone cartilage identified differentially expressed gene cohorts in MCDS that are pathologically relevant (XBP1-independent) or pathologically redundant (XBP1-dependent). XBP1-independent gene expression changes included large-scale transcriptional attenuation of genes encoding secreted proteins and disrupted differentiation from proliferative to hypertrophic chondrocytes. Moreover, these changes were consistent with disruption of C/EBP-β, a master regulator of chondrocyte differentiation, by CHOP, a transcription factor downstream of PERK that inhibits C/EBP proteins, and down-regulation of C/EBP-β transcriptional co-factors, GADD45-β and RUNX2. Thus we propose that the pathology of MCDS is underpinned by XBP1 independent UPR-induced dysregulation of C/EBP-β-mediated chondrocyte differentiation. Our data suggest that modulation of C/EBP-β activity in MCDS chondrocytes may offer therapeutic opportunities.
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http://dx.doi.org/10.1371/journal.pgen.1005505DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4651170PMC
September 2015

A mouse splice-site mutant and individuals with atypical chromosome 22q11.2 deletions demonstrate the crucial role for crkl in craniofacial and pharyngeal development.

Mol Syndromol 2014 Dec 8;5(6):276-86. Epub 2014 Nov 8.

Murdoch Childrens Research Institute, Department of Plastic and Maxillofacial Surgery, Royal Children's Hospital, Parkville, Vic., Australia ; Department of Paediatrics, University of Melbourne, Parkville, Vic., Australia.

The 22q11.2 deletion syndrome (22q11DS) is thought to be a contiguous gene syndrome caused by haploinsufficiency for a variable number of genes with overlapping function during the development of the craniofacial, pharyngeal and cardiac structures. The complexity of genetic and developmental anomalies resulting in 22q11DS has made attributing causation to specific genes difficult. The CRKL gene resides within the common 3-Mb region, most frequently affected in 22q11DS, and has been shown to play an essential role in the development of tissues affected in 22q11DS. Here, we report the characterisation of a mouse strain we named 'snoopy', harbouring a novel Crkl splice-site mutation that results in a loss of Crkl expression. The snoopy strain exhibits a variable phenotype that includes micrognathia, pharyngeal occlusion, aglossia and holoprosencephaly, and altered retinoic acid and endothelin signalling. Together, these features are reminiscent of malformations occurring in auriculocondylar syndrome and agnathia-otocephaly complex, 2 conditions not previously associated with the CRKL function. Comparison of the features of a cohort of patients harbouring small 22q11.2 deletions centred over the CRKL gene, but sparing TBX1, highlights the role of CRKL in contributing to the craniofacial features of 22q11DS. These analyses demonstrate the central role of Crkl in regulating signalling events in the developing oropharyngeal complex and its potential to contribute to dysmorphology.
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http://dx.doi.org/10.1159/000368865DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4281577PMC
December 2014

bfb, a novel ENU-induced blebs mutant resulting from a missense mutation in Fras1.

PLoS One 2013 15;8(10):e76342. Epub 2013 Oct 15.

Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia.

Fras1 is an extracellular matrix associated protein with essential roles in adhesion of epithelia and mesenchyme during early embryonic development. The adhesive function of Fras1 is achieved through interaction with a group of related proteins, Frem 1-3, and a cytoplasmic adaptor protein Grip1. Mutation of each of these proteins results in characteristic epithelial blistering and have therefore become known as "blebs" proteins. Human Fraser syndrome presents with a similar phenotype and the blebs mice have been instrumental in identification of the genetic basis of Fraser syndrome. We have identified a new ENU-induced blebs allele resulting from a novel missense mutation in Fras1. The resulting mouse strain, blood filled blisters (bfb), presents with a classic blebs phenotype but does not exhibit embryonic lethality typical of other blebs mutants and in addition, we report novel palate and sternal defects. Analysis of the bfb phenotype confirms the presence of epithelial-mesenchymal adhesion defects but also supports the emerging role of blebs proteins in regulating signalling during organogenesis. The bfb strain provides new opportunities to investigate the role of Fras1 in development.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0076342PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3797057PMC
June 2014

Cauli: a mouse strain with an Ift140 mutation that results in a skeletal ciliopathy modelling Jeune syndrome.

PLoS Genet 2013 Aug 29;9(8):e1003746. Epub 2013 Aug 29.

Murdoch Childrens Research Institute, Parkville, Victoria, Australia.

Cilia are architecturally complex organelles that protrude from the cell membrane and have signalling, sensory and motility functions that are central to normal tissue development and homeostasis. There are two broad categories of cilia; motile and non-motile, or primary, cilia. The central role of primary cilia in health and disease has become prominent in the past decade with the recognition of a number of human syndromes that result from defects in the formation or function of primary cilia. This rapidly growing class of conditions, now known as ciliopathies, impact the development of a diverse range of tissues including the neural axis, craniofacial structures, skeleton, kidneys, eyes and lungs. The broad impact of cilia dysfunction on development reflects the pivotal position of the primary cilia within a signalling nexus involving a growing number of growth factor systems including Hedgehog, Pdgf, Fgf, Hippo, Notch and both canonical Wnt and planar cell polarity. We have identified a novel ENU mutant allele of Ift140, which causes a mid-gestation embryonic lethal phenotype in homozygous mutant mice. Mutant embryos exhibit a range of phenotypes including exencephaly and spina bifida, craniofacial dysmorphism, digit anomalies, cardiac anomalies and somite patterning defects. A number of these phenotypes can be attributed to alterations in Hedgehog signalling, although additional signalling systems are also likely to be involved. We also report the identification of a homozygous recessive mutation in IFT140 in a Jeune syndrome patient. This ENU-induced Jeune syndrome model will be useful in delineating the origins of dysmorphology in human ciliopathies.
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http://dx.doi.org/10.1371/journal.pgen.1003746DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3757063PMC
August 2013

The circadian clock in murine chondrocytes regulates genes controlling key aspects of cartilage homeostasis.

Arthritis Rheum 2013 Sep;65(9):2334-45

University of Manchester, Manchester, UK.

Objective: To characterize the circadian clock in murine cartilage tissue and identify tissue-specific clock target genes, and to investigate whether the circadian clock changes during aging or during cartilage degeneration using an experimental mouse model of osteoarthritis (OA).

Methods: Cartilage explants were obtained from aged and young adult mice after transduction with the circadian clock fusion protein reporter PER2::luc, and real-time bioluminescence recordings were used to characterize the properties of the clock. Time-series microarrays were performed on mouse cartilage tissue to identify genes expressed in a circadian manner. Rhythmic genes were confirmed by quantitative reverse transcription-polymerase chain reaction using mouse tissue, primary chondrocytes, and a human chondrocyte cell line. Experimental OA was induced in mice by destabilization of the medial meniscus (DMM), and articular cartilage samples were microdissected and subjected to microarray analysis.

Results: Mouse cartilage tissue and a human chondrocyte cell line were found to contain intrinsic molecular circadian clocks. The cartilage clock could be reset by temperature signals, while the circadian period was temperature compensated. PER2::luc bioluminescence demonstrated that circadian oscillations were significantly lower in amplitude in cartilage from aged mice. Time-series microarray analyses of the mouse tissue identified the first circadian transcriptome in cartilage, revealing that 615 genes (∼3.9% of the expressed genes) displayed a circadian pattern of expression. This included genes involved in cartilage homeostasis and survival, as well as genes with potential importance in the pathogenesis of OA. Several clock genes were disrupted in the early stages of cartilage degeneration in the DMM mouse model of OA.

Conclusion: These results reveal an autonomous circadian clock in chondrocytes that can be implicated in key aspects of cartilage biology and pathology. Consequently, circadian disruption (e.g., during aging) may compromise tissue homeostasis and increase susceptibility to joint damage or disease.
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http://dx.doi.org/10.1002/art.38035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3888512PMC
September 2013

Nonsense-mediated mRNA decay of collagen -emerging complexity in RNA surveillance mechanisms.

J Cell Sci 2013 Jun 31;126(Pt 12):2551-60. Epub 2013 May 31.

Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville 3052, Australia.

Nonsense-mediated mRNA decay (NMD) is an evolutionarily conserved mRNA surveillance system that degrades mRNA transcripts that harbour a premature translation-termination codon (PTC), thus reducing the synthesis of truncated proteins that would otherwise have deleterious effects. Although extensive research has identified a conserved repertoire of NMD factors, these studies have been performed with a restricted set of genes and gene constructs with relatively few exons. As a consequence, NMD mechanisms are poorly understood for genes with large 3' terminal exons, and the applicability of the current models to large multi-exon genes is not clear. In this Commentary, we present an overview of the current understanding of NMD and discuss how analysis of nonsense mutations in the collagen gene family has provided new mechanistic insights into this process. Although NMD of the collagen genes with numerous small exons is consistent with the widely accepted exon-junction complex (EJC)-dependent model, the degradation of Col10a1 transcripts with nonsense mutations cannot be explained by any of the current NMD models. Col10a1 NMD might represent a fail-safe mechanism for genes that have large 3' terminal exons. Defining the mechanistic complexity of NMD is important to allow us to understand the pathophysiology of the numerous genetic disorders caused by PTC mutations.
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http://dx.doi.org/10.1242/jcs.120220DOI Listing
June 2013

Comparative proteomic analysis of normal and collagen IX null mouse cartilage reveals altered extracellular matrix composition and novel components of the collagen IX interactome.

J Biol Chem 2013 May 24;288(19):13481-92. Epub 2013 Mar 24.

Center for Biochemistry, Medical Faculty, University of Cologne, Cologne 50931, Germany.

Background: Collagen IX is an integral cartilage extracellular matrix component important in skeletal development and joint function.

Results: Proteomic analysis and validation studies revealed novel alterations in collagen IX null cartilage.

Conclusion: Matrilin-4, collagen XII, thrombospondin-4, fibronectin, βig-h3, and epiphycan are components of the in vivo collagen IX interactome.

Significance: We applied a proteomics approach to advance our understanding of collagen IX ablation in cartilage. The cartilage extracellular matrix is essential for endochondral bone development and joint function. In addition to the major aggrecan/collagen II framework, the interacting complex of collagen IX, matrilin-3, and cartilage oligomeric matrix protein (COMP) is essential for cartilage matrix stability, as mutations in Col9a1, Col9a2, Col9a3, Comp, and Matn3 genes cause multiple epiphyseal dysplasia, in which patients develop early onset osteoarthritis. In mice, collagen IX ablation results in severely disturbed growth plate organization, hypocellular regions, and abnormal chondrocyte shape. This abnormal differentiation is likely to involve altered cell-matrix interactions but the mechanism is not known. To investigate the molecular basis of the collagen IX null phenotype we analyzed global differences in protein abundance between wild-type and knock-out femoral head cartilage by capillary HPLC tandem mass spectrometry. We identified 297 proteins in 3-day cartilage and 397 proteins in 21-day cartilage. Components that were differentially abundant between wild-type and collagen IX-deficient cartilage included 15 extracellular matrix proteins. Collagen IX ablation was associated with dramatically reduced COMP and matrilin-3, consistent with known interactions. Matrilin-1, matrilin-4, epiphycan, and thrombospondin-4 levels were reduced in collagen IX null cartilage, providing the first in vivo evidence for these proteins belonging to the collagen IX interactome. Thrombospondin-4 expression was reduced at the mRNA level, whereas matrilin-4 was verified as a novel collagen IX-binding protein. Furthermore, changes in TGFβ-induced protein βig-h3 and fibronectin abundance were found in the collagen IX knock-out but not associated with COMP ablation, indicating specific involvement in the abnormal collagen IX null cartilage. In addition, the more widespread expression of collagen XII in the collagen IX-deficient cartilage suggests an attempted compensatory response to the absence of collagen IX. Our differential proteomic analysis of cartilage is a novel approach to identify candidate matrix protein interactions in vivo, underpinning further analysis of mutant cartilage lacking other matrix components or harboring disease-causing mutations.
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http://dx.doi.org/10.1074/jbc.M112.444810DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3650385PMC
May 2013

Maintaining mRNA integrity during decalcification of mineralized tissues.

PLoS One 2013 7;8(3):e58154. Epub 2013 Mar 7.

Murdoch Childrens Research Institute, Parkville, Victoria, Australia.

Biomineralization of the extracellular matrix occurs inappropriately in numerous pathological conditions such as cancer and vascular disease, but during normal mammalian development calcification is restricted to the formation of the skeleton and dentition. The comprehensive study of gene expression in mineralized skeletal tissues has been compromized by the traditional decalcification/fixation methods that result in significant mRNA degradation. In this study we developed a novel RNAlater/EDTA decalcification method that protects the integrity of the mRNA in mature mouse tibial epiphyses. Furthermore, this method preserves the tissue structure to allow histological sectioning and microdissection to determine region-specific gene expression, in addition to immuno- and in situ histology. This method will be widely applicable to the molecular analysis of calcified tissues in various pathological conditions, and will be of particular importance in dissection of the gene expression in mouse bone and joint tissues during development and in important clinical conditions such as arthritis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0058154PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3591421PMC
September 2013

Transcriptomics of wild-type mice and mice lacking ADAMTS-5 activity identifies genes involved in osteoarthritis initiation and cartilage destruction.

Arthritis Rheum 2013 Jun;65(6):1547-60

Murdoch Childrens Research Institute and University of Melbourne, Parkville, Victoria, Australia.

Objective: To identify changes in gene expression in mice with osteoarthritis (OA) in order to explore the mechanisms of the disease.

Methods: Gene expression profiling was performed in cartilage from mice with surgically induced OA. We used wild-type (WT) mice and Adamts5Δcat mice, in which ADAMTS-5 activity is lacking and aggrecan loss and cartilage erosion are inhibited, to distinguish gene expression changes that are independent of ADAMTS-5 activity and cartilage breakdown. Mechanical instability was introduced into the knee joints of 10-week-old male mice via surgical destabilization of the medial meniscus (DMM). Cartilage from the developing lesion in the destabilized medial meniscus and corresponding regions in sham-operated joints was harvested by microdissection at 1, 2, and 6 weeks postsurgery, and RNA was extracted, amplified, and hybridized to whole-genome microarrays.

Results: Several previously identified OA-related genes, including Ptgs2, Crlf1, and Inhba, and novel genes, such as Phdla2 and Il11, were up-regulated in both WT mice and Adamts5Δcat mice, indicating that they are independent of ADAMTS-5 activity. The altered expression of other genes, including Col10a1, the sentinel marker of cartilage hypertrophy, and Wnt/β-catenin pathway genes, required ADAMTS-5 activity. Cell death pathway genes were dysregulated, and Tp53, Foxo4, and Xbp1 endoplasmic reticulum-stress transcriptional networks were activated. Analysis of degradome genes identified up-regulation of many proteases, including Mmp3, Capn2, and the novel cartilage proteases Prss46 and Klk8. Comparison with other studies identified 16 genes also dysregulated in rat and human OA as priorities for study.

Conclusion: We have identified, for the first time, several genes that have an ADAMTS-5-independent role in OA, identifying them as possible OA initiation candidates. This work provides new insights into the sequence of gene dysregulation and the molecular basis of cartilage destruction in OA.
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http://dx.doi.org/10.1002/art.37900DOI Listing
June 2013