Cartilage Oligomeric Matrix Protein Gene Research Articles

Abstract 4409: FBXW7 and BCL9L altered pathways as hallmarks of early-onset colorectal cancer

Abstract Background: The incidence of early-onset colorectal cancer (EO-CRC) has been alarmingly increasing, particularly among non-Hispanic Whites (NHWs), resulting in similar rates to ones in African Americans (AAs). Overall, the median age of diagnosis has decreased from 72 to 66 years. The molecular features that could potentially distinguish this phenotype are still not well-established. This study aimed to identify genetic, epigenetic, and transcriptomic factors associated with EO-CRC. Methods: 510 patients with microsatellite-stable tumors analyzed for somatic mutations, targeting 20 cancer driver genes. We included a cohort of 175 AAs from the Yale New Haven Health System, a previously studied cohort of 51 AAs from the Chicago Colorectal Cancer Consortium, and the publicly available molecular data from TCGA COAD-READ PanCancer cohort (50 AAs and 229 NHWs). We analyzed the transcriptomic and methylation profiles from the Yale cohort using Tempo-SeqTM and Illumina EPIC array, respectively. Results: Of the 510 patients, 18% were diagnosed with EO-CRC. Using a multiple variant analysis, adjusting for sex, race, tumor location, and stage, EO-CRC patients were less likely to be male (OR = 0.59, 95% CI: 0.37-0.94, p-value = 0.03), their tumors lacked mutations in APC (OR = 0.37, 95% CI: 0.22-0.63, p-value = 0.0002), and they were more likely to have mutations in FBXW7 (OR = 3.1, 95% CI: 1.60-6.00, p-value = 0.0007) and BCL9L (OR = 3.1, 95% CI: 1.00-8.72, p-value = 0.04). We compared tumors with and without mutations in FBXW7 or BCL9L in two independently analyses. Combining transcriptomics and methylation data, we identified 10 candidate genes that showed significant gene downregulation with hypermethylation or upregulation with hypomethylation. Among FBXW7 mutant tumors, we found the Cartilage oligomeric matrix protein (COMP) gene was significantly downregulated and hypermethylated. In CRC, COMP has been associated with a crosstalk between the TGF-β pathway and immune cell infiltration. Moreover, inactivation of FBXW7 resulted in the accumulation of phosphorylated TGIF1 molecules and repression of TGFβ-dependent transcription in cancer cell lines. Deficiency of FBXW7 is a key element in the phosphorylation-dependent ubiquitination and subsequent proteasome degradation of oncoproteins, such as c-MYC, NOTCH, and Cyclin E. Among BCL9L mutant tumors, keratin 20 (KRT20), the intermediate filament protein and marker of intestinal differentiation in CRC, was downregulated and hypermethylated. BCL9L plays an important role in tumorigenesis induced by aberrant Wnt signaling or aneuploidy tolerance. Conclusion: Our findings further demonstrate the importance of specific etiologic mechanisms in EO-CRC at the level of somatic alterations, providing new ways to understand the biology of EO-CRC and prospects for the development of targeted therapies. Citation Format: Reger Mikaeel, Dante Bellomo, Seeta Rajpara, David Buckley, Mary Yagle, Baris Kerimoglu, Curtis Thorne, Megha Padi, Bodour Salhia, Nathan A. Ellis, Xavier Llor, Rosa Xicola. FBXW7 and BCL9L altered pathways as hallmarks of early-onset colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4409.

Functional characterization of a rare pathogenic variant c.875G>A, p.(Cys292Tyr) in COMP.

The protein encoded by the cartilage oligomeric matrix protein (COMP) gene is a noncollagenous extracellular matrix (ECM) protein that is important for chondrocyte formation and growth. Variations in the COMP gene cause pseudoachondroplasia (PSACH), which is mainly characterized by short-limbed dwarfing in the clinic. To characterize the function of a rare pathogenic variant in the COMP gene (c.875G>A, p.Cys292Tyr). We performed 3D structural analysis, in vitro expression analysis, and immunofluorescence to characterize the effects of the variant on protein structure, expression, and cellular localization respectively. Variation modeling showed that the interactions between amino acids were changed after the variation, and there were 31 changes in the secondary structure of mutant COMP (MT-COMP). Western blot showed that the intracellular quantity of MT-COMP was higher than the wild-type COMP (WT-COMP). Cellular immunofluorescence results showed that WT-COMP was less abundant and homogenously distributed in cells, while the MT-COMP accumulated in the cytoplasm. Herein, we report a variant of COMP in a Chinese family with PSACH. We have shown that the rare missense variant, COMP c.875G>A, previously reported in ClinVar and identified in our patient, results in excessive accumulation of mutant protein in the cytoplasm, and is therefore pathogenic. Through in silico and experimental analyses, we provide evidence that COMP c.875G>A is the likely cause of PSACH in a Chinese family.

Co-occurrence of neurofibromatosis type 1 and pseudoachondroplasia – a first case report

BackgroundNeurofibromatosis type 1 and pseudoachondroplasia are both rare autosomal dominant disorders, caused by pathogenic mutations in NF1 and COMP genes, respectively. Both neurofibromin 1 and cartilage oligomeric matrix protein (COMP) play a role in the development of the skeleton. Carrying both germline mutations has not been previously reported; however, it can affect the developing phenotype.Case presentationThe index patient, an 8-year-old female presented with several skeletal and dermatologic anomalies resembling the coexistence of multiple syndromes. Her mother had dermatologic symptoms characteristic for neurofibromatosis type 1, and her father presented with distinct skeletal anomalies. NGS-based analysis revealed a heterozygous pathogenic mutation in genes NF1 and COMP in the index patient. A previously unreported heterozygous variant was detected for the NF1 gene. The sequencing of the COMP gene revealed a previously reported, pathogenic heterozygous variant that is responsible for the development of the pseudoachondroplasia phenotype.ConclusionsHere, we present the case of a young female carrying pathogenic NF1 and COMP mutations, diagnosed with two distinct heritable disorders, neurofibromatosis type 1 and pseudoachondroplasia. The coincidence of two monogenic autosomal dominant disorders is rare and can pose a differential diagnostic challenge. To the best of our knowledge, this is the first reported co-occurrence of these syndromes.

Anti-inflammatory and pro-anabolic effects of 5-aminosalicylic acid on human inflammatory osteoarthritis models.

Osteoarthritis (OA) is the most common degenerative joint disease, mainly affecting the elderly worldwide, for which the drug treatment remains a major challenge. Low-grade inflammation plays a pivotal role in OA onset and progression. Exploration of notable anti-inflammatory and disease-modifying drugs on human samples could facilitate the evaluation of therapeutic strategies for OA. The anti-inflammatory drug 5-aminosalicylic acid (5-ASA) is a first-line drug for ulcerative colitis (UC), however no study has explored the effects of 5-ASA on articular chondrocytes. In this work, both in vitro (chondrocyte pellets) and ex vivo (osteochondral explants) human inflammatory OA models were applied to evaluate the effects of 5-ASA. In the inflammatory pellet model, 5-ASA remarkably downregulated the gene expression of interleukin-6 (IL-6), and cyclooxygenase-2 (COX-2) while upregulating proteoglycan 4 (PRG4) and cartilage oligomeric matrix protein (COMP) gene expression. Total glycosaminoglycan (GAG) synthesis by pellets was markedly increased in 5-ASA-treated groups compared with the inflammatory group. In conditioned medium, inflammatory mediators (IL-8, nitric oxide) were markedly inhibited upon 5-ASA treatment. Moreover, histological staining showed 5-ASA retained proteoglycan content and inhibited degradation of extracellular matrix (ECM) core components, aggrecan (ACAN) and collagen type II (COL2). In the inflammatory explant model, 5-ASA mitigated signs of OA development by reducing inflammatory mediators and GAG loss. These findings suggest that 5-ASA has anti-inflammatory and pro-anabolic effects on human chondrocyte pellet and osteochondral explant inflammatory OA models. Disease-modifying OA drugs are an unmet clinical need for the treatment of OA. Our study explored and demonstrated the anti-inflammatory and protective effects of 5-ASA on in vitro and ex vivo human inflammatory OA models, showing its translational potential for OA treatment.

Novel and recurrent COMP gene variants in five Japanese patients with pseudoachondroplasia: skeletal changes from the neonatal to infantile periods.

Pseudoachondroplasia (PSACH) is an autosomal dominant skeletal dysplasia caused by pathogenic variants of cartilage oligomeric matrix protein (COMP). Clinical symptoms of PSACH are characterized by growth disturbances after the first year of life. These disturbances lead to severe short stature with short limbs, brachydactyly, scoliosis, joint laxity, joint pain since childhood, and a normal face. Epimetaphyseal dysplasia, shortened long bones, and short metacarpals and phalanges are common findings on radiological examination. Additionally, anterior tonguing of the vertebral bodies in the lateral view is an important finding in childhood because it is specific to PSACH and normalizes with age. Here, we report five Japanese patients with PSACH, with one recurrent (p.Cys351Tyr) and four novel heterozygous pathogenic COMP variants (p.Asp437Tyr, p.Asp446Gly, p.Asp507Tyr, and p.Asp518Val). These five pathogenic variants were located in the calcium-binding type 3 (T3) repeats. In four of the novel variants, the affected amino acid was aspartic acid, which is abundant in each of the eight T3 repeats. We describe the radiological findings of these five patients. We also retrospectively analyzed the sequential changes in the vertebral body and epimetaphysis of the long bones from the neonatal to infantile periods in a patient with PSACH and congenital heart disease.

Torticollis in Connection with Spine Phenotype.

Purpose: Torticollis is not of uncommon occurrence in orthopaedic departments. Various theories and studies concerning the pathogenesis of the deformity have been suggested. We aimed to highlight and discuss the underlying cervical and spine malformation complex in correlation with torticollis via radiographic and tomographic analysis and its connection with a specific syndromic entity. Methods: Torticollis has been recognised in six patients (2 boys and 4 girls with an age range of 14–18 years), in addition to a couple of parents manifested persistent backpain. A variable spine malformation complex was the main reason behind torticollis. In addition, some patients manifested plagiocephaly, facial asymmetry and scoliosis/kyphoscoliosis. In some patients, conventional radiographs were of limited value because of the overlapping anatomical structures. Three-dimensional reconstruction CT scanning was the modality of choice, which enlightens the path for the phenotypic characterisation. Results: A 16-year-old-boy presented with torticollis in correlation with pathologic aberration of the spine cartilaginous stage was analysed via 3DCT scan. Comprehensive clinical and radiological phenotypes were in favour of spondylomegepiphyseal dysplasia. The genotype showed a mutation of the NKX3-2 (BAPX1) gene compatible with the diagnosis of spondylo-meg-epiphyseal-metaphyseal dysplasia. His younger male sibling and parents were heterozygous carriers. In two patients with pseudoachondroplasia syndrome, in which odontoid hypoplasia associated with cervical spine synchondrosis causing life-threatening torticollis, Cartilage oligomeric matrix protein (COMP) gene mutation was identified. MURCS syndrome has been diagnosed in two unrelated girls. Torticollis associated with cervical kyphosis was the major presentation since early childhood. Interestingly, one girl showed omovertebral bones of the lower cervical and upper thoracic spine. Her karyotype manifested a balanced translocation of 46 XX, t (14q; 15q). Conclusion: To detect the underlying etiological diagnosis of torticollis, a skeletal survey was the primary diagnostic tool. Conventional radiographs of the craniocervical junction and spine resulted in confusing readings because of the overlapping anatomical structures. Cranio-cervical malformation complex could have serious neurological deficits, especially for children with indefinite diagnosis of torticollis. The widely used term of congenital muscular torticollis resulted in morbid or mortal consequences. Moreover, some patients received vigorous physical therapy on the bases of muscular torticollis. Sadly speaking, this resulted in grave complications. Understanding the imaging phenotype and the genotype in such patients is the baseline tool for precise and proper management. The value of this paper is to sensitise physicians and orthopaedic surgeons to the necessity of comprehensive clinical and radiological phenotypic characterisations in patients with long term skeletal pathology.

Clinical, Biochemical, Radiological, Genetic and Therapeutic Analysis of Patients with COMP Gene Variants.

Pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia type 1 (MED1) are two rare skeletal disorders caused by cartilage oligomeric matrix protein (COMP) variants. This study aims to analyze the genotype and phenotype of patients with COMP variants. Clinical information for 14 probands was collected; DNA was extracted from blood for COMP variant detection. Clinical manifestations and radiology scoring systems were established to evaluate the severity of each patient's condition. Serum COMP levels in PSACH patients and healthy subjects were measured. Thirty-nine patients were included, along with 12 PSACH probands and two MED1 probands. Disproportionate short stature, waddling gait, early-onset osteoarthritis and skeletal deformities were the most common features. The height Z-score of PSACH patients correlated negatively with age at evaluation (r = - 0.603, p = 0.01) and the clinical manifestation score (r = - 0.556, p = 0.039). Over 50% of the PSACH patients were overweight/obese. The median serum COMP level in PSACH patients was 16.75ng/ml, which was significantly lower than that in healthy controls (98.53ng/ml; p < 0.001). The condition of MED1 patients was better than that of PSACH patients. Four novel variants of COMP were detected: c.874T>C, c.1123_1134del, c.1531G>A, and c.1576G>T. Height Z-scores and serum COMP levels were significantly lower in patients carrying mutations located in calmodulin-like domains 6, 7, and 8. As the two phenotypes overlap to different degrees, PSACH and MED1 are suggested to combine to produce "spondyloepiphyseal dysplasia, COMP type". Clinical manifestations and radiology scoring systems, serum COMP levels and genotype are important for evaluating patient condition severity.

Clinical characteristics and pathogenic gene analysis in a large pedigree with multiple epiphyseal dysplasia

Objective To provide experimental evidence for genetic counseling and prenatal molecular diagnosis by analyzing the clinical characteristics and screening for pathogenic genes of a five-generation suspected multiple epiphyseal dysplasia (MED) family (17 patients). Methods The family members' medical history, general physical examination and hip joint X-ray examination were collected. Peripheral blood samples of the family members were collected and DNA were extracted from these samples. The exons of clinical genes from probands' DNA were sequenced by High throughput sequencing method. Next Gene software was used to compare and analyze the sequence and INGENUITY software was further used to annotate the mutations in order to find the pathogenic mutations in probands. The suspicious mutations were confirmed in pedigree members by PCR and Sanger sequencing. Results The family consisted of 5 generations and 38 members. Pedigree analysis was consistent with autosomal dominant inheritance. There were 17 patients in the family, and their clinical manifestations showed abnormal walking posture in childhood, pain in hip and knee joints, and typical pathological changes of epiphyseal dysplasia on X-ray. Cartilage oligomeric matrix protein (COMP) gene c.1153G>A (p.Asp385Asn) missense heterozygous mutation was screened in proband, which was genotypically and phenotypically segregated in the pedigree. Conclusion A missense mutation of the comp gene has been identified in a pedigree affected with MED which was the first reported in a big family. Our result is conducive to the further diagnosis and treatment and also provides a molecular basisfor the future prenatal diagnosis. Key words: Osteochondrodysplasias; Pedigree; DNA, intergenic; DNA mutational analysis

Clinical characteristics of pseudoachondroplasia and analysis of COMP gene mutation

Objective This article reported the clinical characteristics and gene mutations of two pseudoachondroplasia cases, and made a literature review in order to improve clinicians′ understanding of the disease. Methods Clinical features of two patients who were short stature accompanied with skeletal deformities were summarized, and they accepted whole exome sequencing. We also reviewed literature to summarize the clinical characteristics and known gene research progress of all reported Chinese pseudoachondroplasia cases. Results The two patients′ clinical characteristics were short limbdwarfism with skeletal deformity. Genetic results showed that there were two heterozygous mutations in the cartilage oligomeric matrix protein (COMP) gene of the two patients, c. 1417_1419delGAC and c. 1552G>A, respectively. Up to March 2019, a total of 58 cases of pseudoachondroplasia have been reported in China. The median height of these patients is -5.03 SDS. The clinical features include abnormal gait, short limbs, short fingers/toes, scoliosis, bracelet sign, ankle sign and other skeletal deformities. COMP is the pathogenic gene and mutations mainly located in calmodulin-like domains. The hotspot mutation is c. 1417_1419delGAC. Conclusions Pseudoachondroplasia is a kind of rare genetic disease characterized by short stature and skeletal deformities. The clinical and genetic characteristics of the disease were summarized, which may improve the early diagnosis rate. Key words: Pseudoachondroplasia; Cartilage oligomeric matrix protein; Gene mutation; Molecular mechanism

A constellation of orthopaedic deformities in connection with cartilage oligomeric matrix protein mutation.

Background:Trendelenburg's gait can be observed in Legg-Calvé-Perthes disease, antalgic gait observed in osteoarthropathy and waddling gait is usually seen in genu varum and circumduction gait in patients with genu valgum. Disabling pain was a prime manifestation in slipped capital femoral epiphysis (SCFE). Limited joint range of motion with an inability to bear full weight on an affected extremity with swaying and wide-based gait is seen in patients with malalignment of the lower limbs. All the above-mentioned deformities have been labelled as idiopathic. The main objective of this article is to approach to the aetiology understanding.Patients and Methods:Ten children (3 girls and 7 boys with age average of 9 years) presented with variable deformities; Perthes-like deformity, genu varum/valgum and osteoarthropathy and one patient with SCFE. Clinical and radiological phenotypes were the baseline tool of diagnosis. Genotypic characterisations were performed.Results:Diverse clinical presentations of Perthes-like disease, osteoarthropathy, genu varum/valgum and SCFE were the most prominent skeletal abnormalities in patients manifested cartilage oligomeric matrix protein (COMP) gene mutation.Conclusion:The value of presenting this article is fourfold; first to signify that mutation study was essential for the increment of knowledge related to the genotype–phenotype relationships. Second, to indicate that professional awareness is needed to differentiate between the hidden pathologies in patients with Perthes-like deformity, genu varum, genu valgum and early osteoarthritis in correlation with COMP gene mutation. Third, it is mandatory to question the validity of the term idiopathic. Fourth, this article is an attempt to sensitise orthopaedic physicians and surgeons that deformities might be stemmed from diverse forms of intrinsic bone disorders.

COMP Gene Coexpresses With EMT Genes and Is Associated With Poor Survival in Colon Cancer Patients

BackgroundAbout 1.2 million new cases of colon cancer (CC) and 0.6 million deaths are reported every year, establishing CC as an important contributor to worldwide cancer morbidity and mortality. Although the overall incidence and mortality of CC have declined over the past 3 decades, the number of early-onset colon cancer ([EOCC], patients <50 y old) continues to rise alarmingly. These young patients are often diagnosed at a more advanced stage and tend to have poor survival. Our recently published data showed that the cartilage oligomeric matrix protein (COMP) is overexpressed in early-onset colon cancer patients. COMP is also reported in several cancers to coexpress with epithelial-mesenchymal transition (EMT) transcription factors. Given the role of EMT in cancer metastasis and cell invasion, we assessed the correlation between COMP gene expression and EMT gene expression in CC, and COMP's relationship to patient survival. MethodsmRNA expression of COMP was compared to that of EMT markers using the UCSC Cancer Genomics Browser. Survival analysis was performed using the UCSC Xena Browser for cancer genomics. ResultsExpression analysis revealed coexpression of COMP with the EMT markers CDH2, FN1, VIM, TWIST1, TWIST2, SNAI1, SNAI2, ZEB1, ZEB2, POSTN, MMP2, MMP9, and COL1A1. Samples that were more mesenchymal had higher expression levels of COMP and EMT markers, thus suggesting a potential role of COMP in EMT. Patients with increased COMP expression presented with poorer overall survival compared to patients with no change or reduced COMP expression (P = 0.02). ConclusionsThese findings reveal COMP as a potential biomarker for CC especially in more aggressive CC and CC in young patients, with a likely role in EMT during tumor metastasis and invasion, and a contributing factor to patient survival.

Whole-Exome Sequencing Reveals a Recurrent D401N Mutation in the COMP gene that Causes Multiple Epiphyseal Dysplasia

Multiple epiphyseal dysplasia (MED) is a rare osteochondrodysplasia characterized by moderate short limb dwarfism and earlyonset osteoarthrosis. By whole-exome sequencing (WES), we identified a dominantly inherited mutation (c.1201G>A; p.D401N) in cartilage oligomeric matrix protein (COMP) in a large four-generation Chinese family. Immunofluorescence analysis revealed mutant COMP secretion was severely impaired. Our result expands the mutational spectrum of COMP and provides strong evidence for the genotype-phenotype correlation of COMP pathogenicity in MED.

A novel mutation in exon 11 of COMP gene in a Chinese family with pseudoachondroplasia

Pseudoachondroplasia (PSACH) is a relatively common skeletal dysplasia characterized by disproportionate short stature, joint laxity, early-onset osteoarthrosis, and dysplasia of the spine, epiphysis, and metaphysis. It is known as an autosomal dominant disease which results exclusively from mutations in the gene for Cartilage Oligomeric Matrix Protein (COMP). We have identified a five year old Chinese boy who was diagnosed as pseudoachondroplasia according to clinical manifestations and X-ray symptoms. His mother seems like another effected individual because of the apparent short stature. Genomic DNA was extracted from peripheral blood lymphocytes. DNA sequencing analysis of the COMP gene revealed a heterozygous mutation (c.1219 T > C,p.Cys407Arg) in the patient. His mother was also affected with the same genetic change. Mutations in COMP gene is proved to change the Cartilage Oligomeric Matrix Protein. This missense mutation (c.1219 T > C) has not been reported before and it is not belongs to polymorphism sites. Our results extend the spectrum of mutations in COMP gene leading to pseudoachondroplasia.

Are Intervertebral Disc Tissue Cells Damaged When Attempting to Prevent Thrombus Formation Using Dabigatran, A New Oral Anticoagulant?

To investigate the effect of dabigatran, a new oral anticoagulant, on human primary cell cultures isolated from intact intervertebral disc tissue. Cell cultures were prepared from tissues obtained from six cases who had undergone surgery due to spinal trauma. Dabigatran, an active pharmacological agent, was applied to intact annulus fibrosus (AF)/nucleus pulposus (NP) primary cell cultures from the study group. After performing cell viability, toxicity, and proliferation tests on all cultures in the control and study groups, the surface morphologies of the samples were evaluated. Subsequently, chondroadherin (CHAD), cartilage oligomeric matrix protein (COMP), and matrix metalloproteinase (MMP)-13 and -19 expressions were measured via a real-time polymerase chain reaction (RT-PCR). Data were analyzed statistically. In the proliferation assays performed on the 20th day of the study, cells in the dabigatran-supplemented group were reported to have lost 46.37% more viability than those in the control group. Expressions of all genes examined except MMP-13 were evaluated in the control group by time, but in contrast to the control group results, COMP and MMP-19 gene expressions decreased in the dabigatran-treated group. No CHAD or MMP-13 expression was noted in these cultures. The potential for a systemically applied drug to accumulate in tissue and negatively affect surrounding tissues and microstructures must be emphasized.

A B–Z junction induced by an A … A mismatch in GAC repeats in the gene for cartilage oligomeric matrix protein promotes binding with the hZαADAR1 protein

GAC repeat expansion from five to seven in the exonic region of the gene for cartilage oligomeric matrix protein (COMP) leads to pseudoachondroplasia, a skeletal abnormality. However, the molecular mechanism by which GAC expansions in the COMP gene lead to skeletal dysplasias is poorly understood. Here we used molecular dynamics simulations, which indicate that an A … A mismatch in a d(GAC)6·d(GAC)6 duplex induces negative supercoiling, leading to a local B-to-Z DNA transition. This transition facilitates the binding of d(GAC)7·d(GAC)7 with the Zα-binding domain of human adenosine deaminase acting on RNA 1 (ADAR1, hZαADAR1), as confirmed by CD, NMR, and microscale thermophoresis studies. The CD results indicated that hZαADAR1 recognizes the zigzag backbone of d(GAC)7·d(GAC)7 at the B-Z junction and subsequently converts it into Z-DNA via the so-called passive mechanism. Molecular dynamics simulations carried out for the modeled hZαADAR1-d(GAC)6d(GAC)6 complex confirmed the retention of previously reported important interactions between the two molecules. These findings suggest that hZαADAR1 binding with the GAC hairpin stem in COMP can lead to a non-genetic, RNA editing-mediated substitution in COMP that may then play a crucial role in the development of pseudoachondroplasia.

Novel mutations in the cartilage oligomeric matrix protein gene identified in two Taiwanese patients with pseudoachondroplasia and multiple epiphyseal dysplasia

Novel mutations in the cartilage oligomeric matrix protein gene identified in two Taiwanese patients with pseudoachondroplasia and multiple epiphyseal dysplasia

Quantitative evaluation of the relationship between COMP promoter methylation and the susceptibility and curve progression of adolescent idiopathic scoliosis.

The cartilage oligomeric matrix protein (COMP) was reported to be down-regulated in adolescent idiopathic scoliosis (AIS). The purposes of the study were to evaluate the roles of COMP promoter methylation on the abnormal gene expression and the epigenetic phenotype in AIS. DNA samples of 50 AIS patients and 50 healthy controls were analyzed. Five CpG sites of COMP gene were amplified and sequenced using the polymerase chain reaction (PCR) and the pyrophosphate sequencing technology, while the COMP gene expression was evaluated using real-time PCR. Comparisons were analyzed with the Chi-square test and independent t test. Pearson coefficients of correlation were used to evaluate the association between gene methylation and clinical phenotypes. The average COMP gene promoter methylation of the AIS and control groups was 12.26±2.36 and 8.76±1.94 (p<0.0001), and correspondingly the relative expression of COMP gene expression was 0.52±0.12 and 1.16±0.52 (p<0.001), respectively. The correlation analysis showed significantly negative correlation between methylation level and gene expression (p<0.0001). The comparison analysis between AIS patients with positive and negative methylation showed significant difference in chronological age (p<0.001) and Cobb angle of main curve (p=0.011). The methylation level of the COMP promoters was significantly correlated with Cobb angle of main curve and age (p<0.0001) among the five CpG sites. AIS patients had significantly high COMP promoter methylation and low gene expression. Positive and high COMP promoter methylation was correlated with young age and high Cobb angle of main curve. Therefore, COMP gene promoter methylation may provide significant prognostic information in predicting the susceptibility and curve progression of AIS.

The role and mechanism of plasma microRNA-146a in the early diagnosis of osteoarthritis

Objective To investigate the difference of microRNA (miRNA, miR)-146a-3p in plasma of patients with different grades of osteoarthritis (OA), and explore its molecular mechanism in the early development of OA. Methods The expression of miR-146a-3p was detected by real-time fluorescent quantitative polymerase chain reaction (FQ-PCR) both in plasma of patients with different grades of OA and OA cell models. The mRNA expression of OA related factors, such as cartilage oligomeric matrix protein (COMP), matrix metalloproteinase-13 (MMP-13), collagen type Ⅱ alpha 1 (COL2A1) and a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5), was detected in human articular chondrocytes after transient transfection of miR-146a-3p mimics/inhibitor. The miR-146a-3p target genes were predicted by bioinformatics methods. Results With the increase of OA grades, the plasma miR-146a-3p content was gradually decreased (F=3.15, P=0.012). The miR-146a-3p level in pre-OA group (4.41±2.55) was between the control group (2.79±1.59) and OA I group (5.52±2.48). The expression of miR-146a-3p in human articular chondrocytes was decreased significantly with the time of IL-1β treatment (F=24.32, P=0.000). After transient transfection of miR-146a-3p mimics/inhibitor, the expression of COMP and MMP-13 gene in human articular chondrocytes changed reversely with miR-146a-3p expression levels. MiRanda database predicts that COMP and MMP-13 may be the target genes of miR-146a-3p. Conclusion MiR-146a-3p is involved in the early development of OA. It may play a biological role by down-regulating MMP-13 and COMP, which provids a new biomarker and therapeutic target for early OA diagnosis and treatment. Key words: Osteoarthritis; MicroRNA-146a-3p; Articular chondrocytes; Cartilage oligomeric matrix protein; Matrix metalloproteinase-13

Cartilage oligomeric matrix protein improves in vivo cartilage regeneration and compression modulus by enhancing matrix assembly and synthesis

Cartilage oligomeric matrix protein (COMP), an abundant cartilage extracellular matrix protein, plays an important role in mesenchymal chondrogenesis. To test our hypothesis that COMP could promote tissue engineering cartilage regeneration as well as improve cartilaginous mechanical properties, COMP gene transfected rabbit bone marrow mesenchymal stem cells (BMSCs) were used for chondrogenic differentiation in vitro and were implanted with biphasic scaffolds into osteochondral defects of New Zealand white rabbit trochlear grooves for cartilage regeneration in vivo. In vitro, over expressed COMP could enhance the chondrogenic differentiation and ECM secretion of BMSCs. After euthanasia at 12 weeks post implantation, macroscopic observation, histological staining, mechanical tests and micro-CT were performed for the assessment of repaired cartilage. Overexpression of COMP leads to more newly formed hyaline cartilage and significantly improved mechanical property. These results demonstrated the significant role of COMP in the cartilage regeneration in vivo and offered inspiring advantage of COMP in the application of tissue engineering.

Identification of two novel mutations in the COMP gene in six families with pseudoachondroplasia.

Pseudoachondroplasia (PSACH; MIM no.177170) is an autosomal dominant osteochondrodysplasia characterized by short‑limb short stature, brachydactyly and early‑onset osteoarthropathy. Typically, at approximately two years of age, the rate of growth falls below the standard growth curve, causing a moderately severe form of disproportionate short‑limb short stature. The current study described the clinical and radiographic observations of six Chinese patients with PSACH, and identified two denovo novel missense mutations [p.Asp326Asn (c.976G>A) and c.1585A>G (p.Thr529Ala)] in cartilage oligomeric matrix protein (COMP) in the patients. The current study expanded the mutation spectrum of the COMP gene, and contributes to the understanding of phenotype/genotype of COMP‑associated diseases.