Expression of ADAMTS metalloproteinases in the retinal pigment epithelium derived cell line ARPE-19: transcriptional regulation by TNFalpha

Elevated Plasma Complement Factors in CRB1-Associated Inherited Retinal Dystrophies

Purpose

To determine the profile of inflammation-related proteins and complement system factors in the plasma of CRB1-associated inherited retinal dystrophies (CRB1-IRDs).

Methods

We used the Olink Explore 384 Inflammation II panel for targeted proteomics in 30 cases and 29 controls (cohort I) to identify immune pathways involved in CRB1-IRDs. Genotyping was performed in cohort I and a second cohort of 123 patients from 14 countries and 1292 controls (cohort II).

Results

A significant shift in complement cascade factors was observed in plasma proteomes of CRB1-IRD patients (enrichment for complement cascade, Padj = 3.03 × 10-15). We detected higher plasma levels of complement factor I and complement factor H [CFH] (q = 0.008 and q = 0.046, respectively, adjusted for age and sex), inhibitors of complement component 3 (C3), which correlated significantly (Pearson's coefficient >0.6) with elevated levels of C3 (q = 0.064). The CRB1 missense variants frequently found in patients showed a strong linkage disequilibrium with the common CFH variant rs7535263 (D' = 0.97 for p.(Cys948Tyr); D' = 1.0 for p.(Arg764Cys)), known to be linked with altered plasma CFH-related protein levels. Correction for the CFH genotype revealed significantly elevated plasma levels of CFH-related 2 (CFHR2) in CRB1-IRD patients (q = 0.041).

Conclusions

CRB1-IRDs are characterized by changes in plasma levels of complement factors and proteins of the innate immune system, and linkage between CRB1 and CFH genes implicates functional variants of the CFH-CFHR locus with specific pathogenic variants of CRB1.

Ranibizumab Modifies the Expression of Metalloproteinases and Their Tissue Inhibitors in Peripheral Blood Mononuclear Cells in Patients with Exudative Age-Related Macular Degeneration

BACKGROUND

Age-related macular degeneration (AMD) is the leading cause of vision loss in people over 60 years of age. Despite research, the causes of AMD remain unclear. Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are known to be involved in AMD development, and anti-vascular endothelial growth factor therapy has revolutionized its treatment. This study aims to analyze the changes in gene expression in MMPs and TIMPS in patients with neovascular AMD before and after three doses of ranibizumab.

METHODS

The study involved 29 patients with neovascular AMD treated with ranibizumab. Peripheral blood mononuclear cells were collected before treatment and 24 h after the third dose of ranibizumab. We assessed MMP and TIMP gene expression profiles through oligonucleotide microarrays and validated selected differential genes using RT-qPCR.

RESULTS

A statistically significant change in the expression of six MMP- and TIMP-related genes was observed using oligonucleotide microarray. The mRNA levels of the two genes with the most significant fold changes, MMP15 and TIMP2, were then quantified using RT-qPCR. The results confirmed a statistically significant increase in MMP15 expression and a decrease in TIMP2 levels, although this change was not statistically significant in the group before and after the third dose of ranibizumab.

CONCLUSION

Ranibizumab affects the systemic expression of MMP and TIMP-related genes in patients with neovascular AMD. Results from our exploratory study suggest that MMP15, in particular, may play a role in the treatment response, but further research is necessary.

m6A mRNA Methylation Analysis Provides Novel Insights into Pigmentation in Sheep Skin

N6-methyladenosine (m⁶A) is the most universal post-transcriptional modification of mRNA which may play important roles in verious species. However, the potential roles of m⁶A in the pigmentation of skin are not completely understood. To explore the role of m6A modification in pigmentation of sheep skin, we used MeRIP-seq and RNA-seq to profile the skin transcriptome in black and white coat color (n=3). Our results showed that an average of 7701 m⁶A peaks were obtained for all samples and the average length was 305.89 bp. The GGACUU sequence was the most enrichment motif and shared in black skin and white skin. The m⁶A peaks were mainly enriched in the CDS, 3'UTR and 5'UTR, especially in CDS region near the stop codon of the transcript. 235 significantly differential peaks were found in black skin vs. white skin. The KEGG signaling pathways of downregulated and upregulated m⁶A peaks were mainly enriched in AGE-RAGE signaling pathway in diabetic complications, Viral carcinogenesis, Transcriptional misregulation in cancer, ABC transporters, Basal transcription factors and Thyroid hormone synthesis (P value <0.05). For RNA-seq, 71 differently expressed genes (DEGs) were scanned in black skin vs. white skin. DEGs were significantly enriched in tyrosine metabolism, melanogenesis, neuroactive ligand-receptor interaction pathway (P value <0.05). Combined m⁶A-seq and RNA-seq analysis showed that the hyper-up genes and hypo-up genes were both enriched in ErbB signaling pathway (P value <0.05). In conclusion, it provide a basis for further research into the functions of m⁶A methylation modifications in pigmentation.

ADAMTS6: Emerging roles in cardiovascular, musculoskeletal and cancer biology

ADAMTS family members control mammalian development and disease, primarily through their function as proteases, by regulation of extracellular matrix composition. Until recently, ADAMTS6 was known as one of the orphan proteinases of the nineteen-member family with a relatively unknown expression pattern and function. Emerging focus on this enzyme has started to uncover these unknowns and revealed a vast importance and requirement of ADAMTS6 in cardiovascular and musculoskeletal development. In addition, ADAMTS6 has been linked to numerous disease settings including several types of cancer. This review summarizes the necessity of ADAMTS6 during development, its role in disease and requirement for essential prospective studies to fully realize its biological implications and potential for therapeutic intervention.

Ehlers-Danlos syndromes and their manifestations in the visual system

Ehlers-Danlos syndrome (EDS) is a rare, genetically variable, heterogenous group of (currently recognized) thirteen connective tissue disorders characterized by skin hyperextensibility, tissue fragility, and generalized joint hypermobility. In addition to these commonly recognized phenotypes, recent studies have notably highlighted variable ophthalmic features in EDS. In this review, we comprehensively gather and discuss the ocular manifestations of EDS and its thirteen subtypes in the clinical setting.

Genomic signatures of the evolution of a diurnal lifestyle in Strigiformes

Understanding the targets of selection associated with changes in behavioral traits represents an important challenge of current evolutionary research. Owls (Strigiformes) are a diverse group of birds, most of which are considered nocturnal raptors. However, a few owl species independently adopted a diurnal lifestyle in their recent evolutionary history. We searched for signals of accelerated rates of evolution associated with a diurnal lifestyle using a genome-wide comparative approach. We estimated substitution rates in coding and noncoding conserved regions of the genome of seven owl species, including three diurnal species. Substitution rates of the noncoding elements were more accelerated than those of protein-coding genes. We identified new, owl-specific conserved noncoding elements as candidates of parallel evolution during the emergence of diurnality in owls. Our results shed light on the molecular basis of adaptation to a new niche and highlight the importance of regulatory elements for evolutionary changes in behavior. These elements were often involved in the neuronal development of the brain.

A comprehensive atlas of Aggrecan, Versican, Neurocan and Phosphacan expression across time in wildtype retina and in retinal degeneration

As photoreceptor cells die during retinal degeneration, the surrounding microenvironment undergoes significant changes that are increasingly recognized to play a prominent role in determining the efficacy of therapeutic interventions. Chondroitin Sulphate Proteoglycans (CSPGs) are a major component of the extracellular matrix that have been shown to inhibit neuronal regrowth and regeneration in the brain and spinal cord, but comparatively little is known about their expression in retinal degeneration. Here we provide a comprehensive atlas of the expression patterns of four individual CSPGs in three models of inherited retinal degeneration and wildtype mice. In wildtype mice, Aggrecan presented a biphasic expression, while Neurocan and Phosphacan expression declined dramatically with time and Versican expression remained broadly constant. In degeneration, Aggrecan expression increased markedly in Aipl1-/- and Pde6brd1/rd1, while Versican showed regional increases in the periphery of Rho-/- mice. Conversely, Neurocan and Phosphacan broadly decrease with time in all models. Our data reveal significant heterogeneity in the expression of individual CSPGs. Moreover, there are striking differences in the expression patterns of specific CSPGs in the diseased retina, compared with those reported following injury elsewhere in the CNS. Better understanding of the distinct distributions of individual CSPGs will contribute to creating more permissive microenvironments for neuro-regeneration and repair.

Alternative splicing of the metalloprotease ADAMTS17 spacer regulates secretion and modulates autoproteolytic activity

ADAMTS proteases mediate biosynthesis and breakdown of secreted extracellular matrix (ECM) molecules in numerous physiological and disease processes. In addition to their catalytic domains, ADAMTS proteases contain ancillary domains, which mediate substrate recognition and ECM binding and confer distinctive properties and roles to individual ADAMTS proteases. Although alternative splicing can greatly expand the structural and functional diversity of ADAMTS proteases, it has been infrequently reported and functional consequences have been rarely investigated. Here, we characterize the structural and functional impact of alternative splicing of ADAMTS17, mutations in which cause Weill-Marchesani syndrome 4. Two novel ADAMTS17 splice variants, ADAMTS17A and ADAMTS17B, were investigated by structural modeling, mass spectrometry, and biochemical approaches. Our results identify a novel disulfide-bridged insertion in the ADAMTS17A spacer that originates from inclusion of a novel exon. This insertion results in differential autoproteolysis of ADAMTS17, and thus, predicts altered proteolytic activity against other substrates. The second variant, ADAMTS17B, results from an in-frame exon deletion and prevents ADAMTS17B secretion. Thus, alternative splicing of the ADAMTS spacer significantly regulates the physiologically relevant proteolytic activity of ADAMTS17, either by altering proteolytic specificity (ADAMTS17A) or by altering cellular localization (ADAMTS17B).

Regulation of ADAMTS Proteases

A disintegrin and metalloprotease with thrombospondin type I motifs (ADAMTS) proteases are secreted metalloproteinases that play key roles in the formation, homeostasis and remodeling of the extracellular matrix (ECM). The substrate spectrum of ADAMTS proteases can range from individual ECM proteins to entire families of ECM proteins, such as the hyalectans. ADAMTS-mediated substrate cleavage is required for the formation, remodeling and physiological adaptation of the ECM to the needs of individual tissues and organ systems. However, ADAMTS proteases can also be involved in the destruction of tissues, resulting in pathologies such as arthritis. Specifically, ADAMTS4 and ADAMTS5 contribute to irreparable cartilage erosion by degrading aggrecan, which is a major constituent of cartilage. Arthritic joint damage is a major contributor to musculoskeletal morbidity and the most frequent clinical indication for total joint arthroplasty. Due to the high sequence homology of ADAMTS proteases in their catalytically active site, it remains a formidable challenge to design ADAMTS isotype-specific inhibitors that selectively inhibit ADAMTS proteases responsible for tissue destruction without affecting the beneficial functions of other ADAMTS proteases. In vivo, proteolytic activity of ADAMTS proteases is regulated on the transcriptional and posttranslational level. Here, we review the current knowledge of mechanisms that regulate ADAMTS protease activity in tissues including factors that induce ADAMTS gene expression, consequences of posttranslational modifications such as furin processing, the role of endogenous inhibitors and pharmacological approaches to limit ADAMTS protease activity in tissues, which almost exclusively focus on inhibiting the aggrecanase activity of ADAMTS4 and ADAMTS5.

Matrix Metalloproteinases in Age-Related Macular Degeneration (AMD)

Age-related macular degeneration (AMD) is a complex, multifactorial and progressive retinal disease affecting millions of people worldwide. In developed countries, it is the leading cause of vision loss and legal blindness among the elderly. Although the pathogenesis of AMD is still barely understood, recent studies have reported that disorders in the regulation of the extracellular matrix (ECM) play an important role in its etiopathogenesis. The dynamic metabolism of the ECM is closely regulated by matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs). The present review focuses on the crucial processes that occur at the level of the Bruch’s membrane, with special emphasis on MMPs, TIMPs, and the polymorphisms associated with increased susceptibility to AMD development. A systematic literature search was performed, covering the years 1990–2020, using the following keywords: AMD, extracellular matrix, Bruch’s membrane, MMPs, TIMPs, and MMPs polymorphisms in AMD. In both early and advanced AMD, the pathological dynamic changes of ECM structural components are caused by the dysfunction of specific regulators and by the influence of other regulatory systems connected with both genetic and environmental factors. Better insight into the pathological role of MMP/TIMP complexes may lead to the development of new strategies for AMD treatment and prevention.

Age-related Macular Degeneration: Current Knowledge of Zinc Metalloproteinases Involvement

BACKGROUND

Advanced age-related macular degeneration (AMD) is the leading cause of blindness in the elderly with limited therapeutic options. The disease is characterized by photoreceptor loss in the macula and reduced Retinal Pigment Epithelium (RPE) function, associated with matrix degradation, cell proliferation, neovascularization and inflammation. Matrix metalloproteinases (MMPs), a disintegrin and metalloproteinases (ADAMs) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTSs) play a critical role in the physiology of extracellular matrix (ECM) turnover and, in turn, in ECM pathologies, such as AMD. A balance between the activities of MMPs and Tissue Inhibitors of Metalloproteinase (TIMPs) is crucial for the integrity of the ECM components; indeed, a dysregulation in the ratio of these factors produces profound changes in the ECM, including thickening and deposit formation, which eventually might lead to AMD development.

OBJECTIVE

This article reviews the relevance and impact of zinc metalloproteinases on the development of AMD and their roles as biomarkers and/or therapeutic targets. We illustrate some studies on several inhibitors of MMPs currently used to dissect physiological properties of MMPs. Moreover, all molecules or technologies used to control MMP and ADAM activity in AMD are analyzed.

CONCLUSION

This study underlines the changes in the activity of MMPs expressed by RPE cells, highlights the functions of already used MMP inhibitors and consequently suggests their application as therapeutic agents for the treatment of AMD.

A disintegrin-like and metalloproteinase with thrombospondin-1 (ADAMTS-1) levels in gingival crevicular fluid correlate with vascular endothelial growth factor-A, hypoxia-inducible factor-1α, and clinical parameters in patients with advanced periodontitis

BACKGROUND

ADAMTS (a disintegrin-like and metalloproteinase with thrombospondin) are a family of proteinases that are structurally similar to the family of matrix metalloproteinases with critical roles in damage and repair of the extracellular matrix. Their functions are closely related to inflammation, hypoxia, and vascularization. Our aim was to determine levels of ADAMTS-1 in gingival crevicular fluid (GCF) in patients with advanced periodontal diseases and identify their association with hypoxia-inducible factor-1alpha (HIF-1α), vascular endothelial growth factor (VEGF-A), and clinical parameters of periodontitis.

METHODS

The study consisted of three groups: healthy individuals (control; n = 20), generalized chronic periodontitis (CP; n = 21), and generalized aggressive periodontitis (GAgP; n = 20). Clinical parameters were measured. Levels of ADAMTS-1, VEGF-A, and HIF-1α in GCF and serum were quantified by enzyme-linked immunosorbent assay (ELISA) and reported as total amounts and concentration.

RESULTS

ADAMTS-1 total amount in GCF were significantly higher in patients with CP and GAgP compared with healthy individuals (P < 0.05). HIF-1α total amount in GCF were also higher in periodontitis groups compared with the control group (P < 0.05). GCF total VEGF-A content was significantly higher in the GAgP group compared with the CP and the controls (respectively; P = 0.023, P = 0.003). There was a significant correlation between ADAMTS-1, VEGF-A, and HIF-1α levels in the GCF and clinical periodontal parameters (probing depth [PD], bleeding on probing [BOP], and clinical attachment loss (CAL); P < 0.05).

CONCLUSION

ADAMTS-1 may play a role in advanced periodontal disease pathogenesis in correlation with tissue hypoxia and vascularization.

Identification of pathogenic genes and upstream regulators in age-related macular degeneration

Background

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in older individuals. Our study aims to identify the key genes and upstream regulators in AMD.

Methods

To screen pathogenic genes of AMD, an integrated analysis was performed by using the microarray datasets in AMD derived from the Gene Expression Omnibus (GEO) database. The functional annotation and potential pathways of differentially expressed genes (DEGs) were further discovered by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. We constructed the AMD-specific transcriptional regulatory network to find the crucial transcriptional factors (TFs) which target the DEGs in AMD. Quantitative real time polymerase chain reaction (qRT-PCR) was performed to verify the DEGs and TFs obtained by integrated analysis.

Results

From two GEO datasets obtained, we identified 1280 DEGs (730 up-regulated and 550 down-regulated genes) between AMD and normal control (NC). After KEGG analysis, steroid biosynthesis is a significantly enriched pathway for DEGs. The expression of 8 genes (TNC, GRP, TRAF6, ADAMTS5, GPX3, FAP, DHCR7 and FDFT1) was detected. Except for TNC and GPX3, the other 6 genes in qRT-PCR played the same pattern with that in our integrated analysis.

Conclusions

The dysregulation of these eight genes may involve with the process of AMD. Two crucial transcription factors (c-rel and myogenin) were concluded to play a role in AMD. Especially, myogenin was associated with AMD by regulating TNC, GRP and FAP. Our finding can contribute to developing new potential biomarkers, revealing the underlying pathogenesis, and further raising new therapeutic targets for AMD.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-017-0498-z) contains supplementary material, which is available to authorized users.

Expression of ADAMTS-1, -4, -5 and TIMP-3 in normal and multiple sclerosis CNS white matter

ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) -1, -4 and -5 proteases have been identified in the CNS at the mRNA level. These glutamyl endopeptidases, inhibited by tissue inhibitor of metalloproteinases (TIMP)-3, are key enzymes in the degradation of the aggregating chondroitin sulphate proteoglycans (CSPGs), and may therefore play a role in CNS extracellular matrix (ECM) changes in multiple sclerosis (MS). We have investigated ADAMTS and TIMP-3 expression in normal and MS CNS white matter by real-time RT-PCR, western blotting and immunohistochemistry. We report for the first time the presence of ADAMTS-1, -4 and -5 in normal and MS white matter. Levels of ADAMTS-1 and -5 mRNA were decreased in MS compared to normal tissue, with no significant change in ADAMTS-4 mRNA levels. Protein levels of ADAMTS-4 were significantly higher in MS tissue compared to normal tissue. Immunohistochemical studies demonstrated that ADAMTS-4 was associated predominantly with astrocytes with increased expression within MS lesions. TIMP-3 mRNA was significantly decreased in MS compared to controls. These studies suggest a role for ADAMTS-4 in the pathogenesis of MS. Further studies on the activity of ADAMTS-4 will enable a better understanding of its role in the turnover of the ECM of white matter in MS.

AMD Genetics in India: The Missing Links

Age related macular degeneration is a disease which occurs in aged individuals. There are various changes that occur at the cellular, molecular and physiological level with advancing age (Samiec et al., 1988; Sharma K. et al., 2014). Drusen deposition between retinal pigment epithelium (RPE) and Bruch’s membrane (BM) is one of the key features in AMD patients (Mullins et al., 2000; Hageman et al., 2001) similar to Aβ/tau aggregates in Alzheimer’s disease (AD) patients. The primary goal of this review is to discuss whether the various candidate genes and associated biomarkers, that are known to play an independent role in progression of AMD, exert deleterious effect on phenotype, alone or in combination, in Indian AMD patients from the same ethnic group and the significance of such research. A statistical model for probable interaction between genes could be derived from such analysis. Therefore, one can use multiple modalities to identify and enrol AMD patients based on established clinical criteria and examine the risk factors to determine if these genes are associated with risk factors, biomarkers or disease by Mendelian randomization. Similarly, there are large numbers of single nucleotide polymorphisms (SNPs) identified in human population. Even non-synonymous SNPs (nsSNPs) are believed to induce deleterious effects on the functionality of various proteins. The study of such snSNPs could provide a better genetic insight for diverse phenotypes of AMD patients, predicting significant risk factors for the disease in Indian population. Therefore, the prediction of biological effect of nsSNPs in the candidate genes and the associated grant applications in the subject are highly solicited.Therefore, genotyping and levels of protein expression of various genes would provide wider canvas in genetic complexity of AMD pathology which should be evaluated by valid statistical and bioinformatics’ tools. Longitudinal follow up of Indian AMD patients to evaluate the temporal effect of SNPs and biomarkers on progression of disease would provide a unique strategy in the field.

ADAMTS-7 exhibits elevated expression in cartilage of osteonecrosis of femoral head and has a positive correlation with TNF- α and NF- κ B P65

ADAMTS-7 has been reported to exaggerate cartilage degeneration and to be associated with TNF-α and NF-κB signaling pathway. In this study we compared the expression of ADAMTS-7, TNF-α, and Phospho-NF-κB in patients with femoral neck fracture (FNF) and osteonecrosis of femoral head (ONFH) at different stages. We found that expression of ADAMTS-7, TNF-α, and Phospho-NF-κB was significantly upregulated in ONFH patients' articular cartilage and related to the pathogenesis of ONFH. Thus we conclude that ADAMTS-7 level appears to be positively associated with expression of TNF-α and Phospho-NF-κB P65 in cartilage, which may imply its association with cartilage destruction of ONFH.

Transcriptome analysis reveals the contribution of thermal and the specific effects in cellular response to millimeter wave exposure

Radiofrequency radiations constitute a new form of environmental pollution. Among them, millimeter waves (MMW) will be widely used in the near future for high speed communication systems. This study aimed therefore to evaluate the biocompatibility of MMW at 60 GHz. For this purpose, we used a whole gene expression approach to assess the effect of acute 60 GHz exposure on primary cultures of human keratinocytes. Controls were performed to dissociate the electromagnetic from the thermal effect of MMW. Microarray data were validated by RT-PCR, in order to ensure the reproducibility of the results. MMW exposure at 20 mW/cm², corresponding to the maximum incident power density authorized for public use (local exposure averaged over 1 cm²), led to an increase of temperature and to a strong modification of keratinocyte gene expression (665 genes differentially expressed). Nevertheless, when temperature is artificially maintained constant, no modification in gene expression was observed after MMW exposure. However, a heat shock control did not mimic exactly the MMW effect, suggesting a slight but specific electromagnetic effect under hyperthermia conditions (34 genes differentially expressed). By RT-PCR, we analyzed the time course of the transcriptomic response and 7 genes have been validated as differentially expressed: ADAMTS6, NOG, IL7R, FADD, JUNB, SNAI2 and HIST1H1A. Our data evidenced a specific electromagnetic effect of MMW, which is associated to the cellular response to hyperthermia. This study raises the question of co-exposures associating radiofrequencies and other environmental sources of cellular stress.

ADAMTS-12: a multifaced metalloproteinase in arthritis and inflammation

ADAMTS-12 is a member of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) family of proteases, which were known to play important roles in various biological and pathological processes, such as development, angiogenesis, inflammation, cancer, arthritis, and atherosclerosis. In this review, we briefly summarize the structural organization of ADAMTS-12; concentrate on the emerging role of ADAMTS-12 in several pathophysiological conditions, including intervertebral disc degeneration, tumorigenesis and angioinhibitory effects, pediatric stroke, gonad differentiation, trophoblast invasion, and genetic linkage to schizophrenia and asthma, with special focus on its role in arthritis and inflammation; and end with the perspective research of ADAMTS-12 and its potential as a promising diagnostic and therapeutic target in various kinds of diseases and conditions.

Allelic methylation status of CpG islands on chromosome 21q in patients with Trisomy 21

Trisomy 21 is a chromosomal condition caused by the presence of all or part of an extra 21st chromosome. There has been limited research into the DNA methylation status of CpG islands (CGIs) in trisomy 21, therefore, exploring the DNA methylation status of CGIs in 21q is essential for the development of a series of potential epigenetic biomarkers for prenatal screening of trisomy 21. First, DNA sequences of CGIs in 21q from the USCS database were obtained and 149 sequences and 148 pairs of primers in the BGI YH database were aligned. All 300 cases were analyzed by a heavy methyl-polymerase chain reaction (HM-PCR) assay and a comparison of the DNA methylation status of CGIs was made between trisomy 21 and the control. The HM-PCR assay results did not show a difference in the DNA methylation status between individuals with trisomy 21 and the control. In total, there were 11 CGIs that showed various DNA methylation statuses between Japanese and Chinese patients. Subsequently, bisulfite genomic sequencing found variations in the methylation status of CpG dinucleotides in CGIs (nos. 14, 75, 109, 134 and 146) between trisomy 21 and the control. The different DNA methylation status of CpG dinucleotides in CGIs may be a potential epigenetic marker for diagnosing trisomy 21. No difference was identified in the DNA methylation status of 21q CGIs among Chinese individuals with trisomy 21 and the control. The homogeneity of the DNA methylation status of 21q CGIs in Chinese patients indicates that DNA methylation is likely to be an epigenetic marker distinguishing ethnicities.

Photocoagulation of human retinal pigment epithelial cells in vitro: evaluation of necrosis, apoptosis, cell migration, cell proliferation and expression of tissue repairing and cytoprotective genes

Aims

Sight-threatening diabetic retinopathy has been treated with photocoagulation for decades but the mechanisms behind the beneficial clinical effects are poorly understood. One target of irradiation and a potential player in this process is the retinal pigment epithelium (RPE). Here we establish an in vitro model for photocoagulation of human RPE cells.

Methods

ARPE-19 cells were exposed to photocoagulation and studied at various time points up to 168h. Lesion morphology, necrosis and apoptosis were investigated by light microscopy; LIVE/DEAD staining and measurements of lactate dehydrogenase activity; and TUNEL- and ELISA-based quantification of DNA fragments, respectively. Cell migration and proliferation were explored using docetaxel and mitomycin C; temporal and spatial changes in proliferation were assessed by confocal immunofluorescence of proliferating cell nuclear antigen. Gene expression was measured by qPCR.

Results

Photocoagulation of ARPE-19 resulted in denaturation of proteins and reproducible lesion formation. A transient peak in necrosis, followed by a peak in apoptosis was observed in cells within the lesions at 6h and 24h, respectively after photocoagulation. Cell proliferation was depressed during the first hours after photocoagulation, back to control levels at 24h and augmented in the following days. These effects were not limited to cells in the lesions, but also evident in neighbouring cells. Changes in cell proliferation during lesion repair were preceded by changes in cell migration. Altered mRNA expression of genes previously implicated in the regulation of cell proliferation (FOS, IL-1β, IL-8, HMGA2), migration and tissue repairing (TGFBR2, ADAMTS6, TIMP3, CTGF) was observed, as well as increased expression of the alarmin IL33 and the cytoprotective gene HSPA6.

Conclusions

Using a laser system and experimental settings that comply with standards used in clinical practice, we have established a suitable model for in vitro photocoagulation of human RPE cells to isolate their contribution to the beneficial effects of laser treatment.

Emerging Roles of ADAMTSs in Angiogenesis and Cancer

A Disintegrin-like And Metalloproteinase with ThromboSpondin motifs—ADAMTSs—are a multi-domain, secreted, extracellular zinc metalloproteinase family with 19 members in humans. These extracellular metalloproteinases are known to cleave a wide range of substrates in the extracellular matrix. They have been implicated in various physiological processes, such as extracellular matrix turnover, melanoblast development, interdigital web regression, blood coagulation, ovulation, etc. ADAMTSs are also critical in pathological processes such as arthritis, atherosclerosis, cancer, angiogenesis, wound healing, etc. In the past few years, there has been an explosion of reports concerning the role of ADAMTS family members in angiogenesis and cancer. To date, 10 out of the 19 members have been demonstrated to be involved in regulating angiogenesis and/or cancer. The mechanism involved in their regulation of angiogenesis or cancer differs among different members. Both angiogenesis-dependent and -independent regulation of cancer have been reported. This review summarizes our current understanding on the roles of ADAMTS in angiogenesis and cancer and highlights their implications in cancer therapeutic development.

MicroRNA regulation of human protease genes essential for influenza virus replication

Influenza A virus causes seasonal epidemics and periodic pandemics threatening the health of millions of people each year. Vaccination is an effective strategy for reducing morbidity and mortality, and in the absence of drug resistance, the efficacy of chemoprophylaxis is comparable to that of vaccines. However, the rapid emergence of drug resistance has emphasized the need for new drug targets. Knowledge of the host cell components required for influenza replication has been an area targeted for disease intervention. In this study, the human protease genes required for influenza virus replication were determined and validated using RNA interference approaches. The genes validated as critical for influenza virus replication were ADAMTS7, CPE, DPP3, MST1, and PRSS12, and pathway analysis showed these genes were in global host cell pathways governing inflammation (NF-κB), cAMP/calcium signaling (CRE/CREB), and apoptosis. Analyses of host microRNAs predicted to govern expression of these genes showed that eight miRNAs regulated gene expression during virus replication. These findings identify unique host genes and microRNAs important for influenza replication providing potential new targets for disease intervention strategies.

Modulatory effect of interleukin-1α on expression of structural matrix proteins, MMPs and TIMPs in human cardiac myofibroblasts: role of p38 MAP kinase

The proinflammatory cytokine interleukin-1 (IL-1) elicits catabolic effects on the myocardial extracellular matrix (ECM) early after myocardial infarction but there is little understanding of its direct effects on cardiac myofibroblasts (CMF), or the role of p38 mitogen-activated protein kinase (MAPK). We used a focused RT-PCR microarray to investigate the effects of IL-1α on expression of 41 ECM genes in CMF cultured from different patients, and explored regulation by p38 MAPK. IL-1α (10 ng/ml, 6h) had minimal effect on mRNA expression of structural ECM proteins, including collagens, laminins, fibronectin and vitronectin. However, it induced marked increases in expression of specific ECM proteases, including matrix metalloproteinases MMP-1 (collagenase-1), MMP-3 (stromelysin-1), MMP-9 (gelatinase-B) and MMP-10 (stromelysin-2). Conversely, IL-1α reduced mRNA and protein expression of ADAMTS1, a metalloproteinase that suppresses neovascularization. IL-1α increased expression of TIMP-1 slightly, but not TIMP-2. Data for MMP-1, MMP-2, MMP-3, MMP-9, MMP-10 and ADAMTS1 were confirmed by quantitative real-time RT-PCR. Tumor necrosis factor-alpha (TNFα), another important myocardial proinflammatory cytokine, did not alter expression of these metalloproteinases. IL-1α strongly activated the p38 MAPK pathway in human CMF. Pharmacological inhibitors of p38-α/β (SB203580) or p38-α/β/γ/δ (BIRB-0796) reduced MMP-3 and ADAMTS1 mRNA expression, but neither inhibitor affected MMP-9 levels. MMP-1 and MMP-10 expression were inhibited by BIRB-0796 but not SB203580, suggesting roles for p38-γ/δ. In summary, IL-1α induces a distinct pattern of ECM protein and protease expression in human CMF, in part regulated by distinct p38 MAPK subtypes, affirming the key role of IL-1α and CMF in post-infarction cardiac remodeling.

The role of ADAMTSs in arthritis

The ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family consists of 19 proteases. These enzymes are known to play important roles in development, angiogenesis and coagulation; dysregulation and mutation of these enzymes have been implicated in many disease processes, such as inflammation, cancer, arthritis and atherosclerosis. This review briefly summarizes the structural organization and functional roles of ADAMTSs in normal and pathological conditions, focusing on members that are known to be involved in the degradation of extracellular matrix and loss of cartilage in arthritis, including the aggrecanases (ADAMTS-4 and ADAMTS-5), ADAMTS-7 and ADAMTS-12, the latter two are associated with cartilage oligomeric matrix protein (COMP), a component of the cartilage extracellular matrix (ECM). We will discuss the expression pattern and the regulation of these metalloproteinases at multiple levels, including their interaction with substrates, induction by pro-inflammatory cytokines, protein processing, inhibition (e.g., TIMP-3, alpha-2-macroglobulin, GEP), and activation (e.g., syndecan-4, PACE-4).

The emerging roles of ADAMTS-7 and ADAMTS-12 matrix metalloproteinases

The a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) comprise a family of secreted zinc metalloproteinases with a precisely ordered modular organization. These enzymes play an important role in the turnover of extracellular matrix proteins in various tissues and their dysregulation has been implicated in disease-related processes such as arthritis, atherosclerosis, cancer, and inflammation. ADAMTS-7 and ADAMTS-12 share a similar domain organization to each other and form a subgroup within the ADAMTS family. Emerging evidence suggests that ADAMTS-7 and ADAMTS-12 may play an important role in the development and pathogenesis of various kinds of diseases. In this review, we summarize what is currently known about the roles of these two metalloproteinases, with a special focus on their involvement in chondrogenesis, endochondral ossification, and the pathogenesis of arthritis, atherosclerosis, and cancer. The future study of ADAMTS-7 and ADAMTS-12, as well as the molecules with which they interact, will help us to better understand a variety of human diseases from both a biological and therapeutic standpoint.

ADAMTS1 is a unique hypoxic early response gene expressed by endothelial cells

ADAMTS1 (a disintegrin and metalloproteinase with thrombospondin motifs 1) is a member of the matrix metalloproteinase family. We have previously reported that ADAMTS1 was strongly expressed in myocardial infarction. In this study, we investigated whether hypoxia induced ADAMTS1 and investigated its regulatory mechanism. In hypoxia, the expression level of ADAMTS1 mRNA and protein rapidly increased in endothelial cells, but not in other cell types. Interestingly, the induction of ADAMTS1 by hypoxia was transient, whereas vascular endothelial growth factor induction by hypoxia in human umbilical vein endothelial cells (HUVEC) increased in a time-dependent manner. CoCl2, a transition metal that mimics hypoxia, induced ADAMTS1 in HUVEC. The phosphatidylinositol 3-kinase inhibitor LY294002 dose-dependently inhibited the increase of ADAMTS1 mRNA expression in hypoxia. We characterized the promoter region of ADAMTS1, and the secreted luciferase assay system demonstrated that hypoxia induced luciferase secretion in the culture medium 4.6-fold in HUVEC. In the promoter region of ADAMTS1, we found at least three putative hypoxia-inducible factor (HIF) binding sites, and the chromatin immunoprecipitation assay revealed HIF-1 binding to HIF binding sites in the promoter region of ADAMTS1 under hypoxia. Recombinant ADAMTS1 protein promoted the migration of HUVEC under hypoxic conditions. In summary, we found that ADAMTS1 is transiently induced by hypoxia in endothelial cells, and its transcription is mediated by HIF-1 binding. Our data indicate that ADAMTS1 is a novel acute hypoxia-inducible gene.

The role of ADAMTS-7 and ADAMTS-12 in the pathogenesis of arthritis

Loss of articular cartilage caused by extracellular matrix breakdown is the hallmark of arthritis. Degradative fragments of cartilage oligomeric matrix protein (COMP) have been observed in arthritic patients. ADAMTS-7 and ADAMTS-12, two members of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family, have been associated with COMP degradation in vitro, and are significantly overexpressed in the cartilage and synovium of patients with rheumatoid arthritis. Recent studies have demonstrated the importance of COMP degradation by ADAMTS-7 and ADAMTS-12. Specifically, the size of COMP fragments generated by ADAMTS-7 or ADAMTS-12 is similar to that of COMP-degradative fragments seen in arthritic patients. In addition, antibodies against ADAMTS-7 or ADAMTS-12 dramatically inhibit tumor necrosis factor-induced and interleukin-1beta-induced COMP degradation in cartilage explants. Furthermore, suppression of ADAMTS-7 or ADAMTS-12 expression using the small interfering RNA silencing approach in human chondrocytes markedly prevents COMP degradation. COMP degradation mediated by ADAMTS-7 and ADAMTS-12 is inhibited by alpha(2)-macroglobulin. More significantly, granulin-epithelin precursor, a newly characterized chondrogenic growth factor, disturbs the interaction between COMP and ADAMTS-7 and ADAMTS-12, preventing COMP degradation by these enzymes. This Review summarizes the evidence demonstrating that ADAMTS-7 and ADAMTS-12 are newly identified enzymes responsible for COMP degradation in arthritis, and that alpha(2)-macroglobulin and granulin-epithelin precursor represent their endogenous inhibitors.

Inhibition of ADAMTS-7 and ADAMTS-12 degradation of cartilage oligomeric matrix protein by alpha-2-macroglobulin

OBJECTIVE

As we previously reported, ADAMTS-7 and ADAMTS-12, two members of ADAMTS (a disintegrin and metalloprotease with thrombospondin motifs) family, degrade cartilage oligomeric matrix protein (COMP) in vitro and are significantly induced in the cartilage and synovium of arthritic patients [Liu CJ, Kong W, Ilalov K, Yu S, Xu K, Prazak L, et al. ADAMTS-7: a metalloproteinase that directly binds to and degrades cartilage oligomeric matrix protein. FASEB J 2006;20(7):988-90; Liu CJ, Kong W, Xu K, Luan Y, Ilalov K, Sehgal B, et al. ADAMTS-12 associates with and degrades cartilage oligomeric matrix protein. J Biol Chem 2006;281(23):15800-8]. The purpose of this study was to determine (1) whether cleavage activity of ADAMTS-7 and ADAMTS-12 of COMP are associated with COMP degradation in osteoarthritis (OA); (2) whether alpha-2-macroglobulin (a(2)M) is a novel substrate for ADAMTS-7 and ADAMTS-12; and (3) whether a(2)M inhibits ADAMTS-7 or ADAMTS-12 cleavage of COMP.

METHODS

An in vitro digestion assay was used to examine the degradation of COMP by ADAMTS-7 and ADAMTS-12 in the cartilage of OA patients; in cartilage explants incubated with tumor necrosis factor-alpha (TNF-alpha) or interleukin-1-beta (IL-1beta) with or without blocking antibodies; and in human chondrocytes treated with specific small interfering RNA (siRNA) to knockdown ADAMTS-7 or/and ADAMTS-12. Digestion of a(2)M by ADAMTS-7 and ADAMTS-12 in vitro and the inhibition of ADAMTS-7 or ADAMTS-12-mediated digestion of COMP by a(2)M were also analyzed.

RESULTS

The molecular mass of the COMP fragments produced by either ADAMTS-7 or ADAMTS-12 were similar to those observed in OA patients. Specific blocking antibodies against ADAMTS-7 and ADAMTS-12 dramatically inhibited TNF-alpha- or IL-1beta-induced COMP degradation in the cultured cartilage explants. The suppression of ADAMTS-7 or ADAMTS-12 expression by siRNA silencing in the human chondrocytes also prevented TNF-alpha- or IL-1beta-induced COMP degradation. Both ADAMTS-7 and ADAMTS-12 were able to cleave a(2)M, giving rise to 180- and 105-kDa cleavage products, respectively. Furthermore, a(2)M inhibited both ADAMTS-7- and ADAMTS-12-mediated COMP degradation in a concentration (or dose)-dependent manner.

CONCLUSION

Our observations demonstrate the importance of COMP degradation by ADAMTS-7 and ADAMTS-12 in vivo. Furthermore, a(2)M is a novel substrate for ADAMTS-7 and ADAMTS-12. More significantly, a(2)M represents the first endogenous inhibitor of ADAMTS-7 and ADAMTS-12.

Microarray identifies ADAM family members as key responders to TGF-beta1 in alveolar epithelial cells

The molecular mechanisms of Idiopathic Pulmonary Fibrosis (IPF) remain elusive. Transforming Growth Factor beta 1(TGF-beta1) is a key effector cytokine in the development of lung fibrosis. We used microarray and computational biology strategies to identify genes whose expression is significantly altered in alveolar epithelial cells (A549) in response to TGF-beta1, IL-4 and IL-13 and Epstein Barr virus. A549 cells were exposed to 10 ng/ml TGF-beta1, IL-4 and IL-13 at serial time points. Total RNA was used for hybridisation to Affymetrix Human Genome U133A microarrays. Each in vitro time-point was studied in duplicate and an average RMA value computed. Expression data for each time point was compared to control and a signal log ratio of 0.6 or greater taken to identify significant differential regulation. Using normalised RMA values and unsupervised Average Linkage Hierarchical Cluster Analysis, a list of 312 extracellular matrix (ECM) proteins or modulators of matrix turnover was curated via Onto-Compare and Gene-Ontology (GO) databases for baited cluster analysis of ECM associated genes. Interrogation of the dataset using ontological classification focused cluster analysis revealed coordinate differential expression of a large cohort of extracellular matrix associated genes. Of this grouping members of the ADAM (A disintegrin and Metalloproteinase domain containing) family of genes were differentially expressed. ADAM gene expression was also identified in EBV infected A549 cells as well as IL-13 and IL-4 stimulated cells. We probed pathologenomic activities (activation and functional activity) of ADAM19 and ADAMTS9 using siRNA and collagen assays. Knockdown of these genes resulted in diminished production of collagen in A549 cells exposed to TGF-beta1, suggesting a potential role for these molecules in ECM accumulation in IPF.

An alternative spliced transcript of ADAMTS4 is present in human synovium from OA patients

The major proteoglycan of articular cartilage aggrecan is a substrate for ADAMTS4. RT-PCR analysis of human osteoarthritic (OA) synovial co-cultures using oligonucleotide primers designed to amplify across the exon 8/9 junction of human ADAMTS4 resulted in the amplification of two products, the expected product and a smaller product missing 161 bp from the 5' end of exon 9, the result of alternative splicing in which exon 8 joins to a cryptic 3' splice site within exon 9. The protein produced would be identical to human ADAMTS4 up to Arg(696), and would have a new C-terminal domain with no commonality with the ADAMTS4 spacer domain. Changes in the C-terminal domain of ADAMTS4 may alter its substrate specificity.

ADAMTS-7: a metalloproteinase that directly binds to and degrades cartilage oligomeric matrix protein

Degradative fragments of cartilage oligomeric matrix protein (COMP) have been observed in arthritic patients. The physiological enzyme(s) that degrade COMP, however, remain unknown. We performed a yeast two-hybrid screen (Y2H) to search for proteins that associate with COMP to identify an interaction partner that might degrade it. One screen using the epidermal growth factor (EGF) domain of COMP as bait led to the discovery of ADAMTS-7. Rat ADAMTS-7 is composed of 1595 amino acids, and this protein exhibits higher expression in the musculoskeletal tissues. COMP binds directly to ADAMTS-7 in vitro and in native articular cartilage. ADAMTS-7 selectively interacts with the EGF repeat domain but not with the other three functional domains of COMP, whereas the four C-terminal TSP motifs of ADAMTS-7 are required and sufficient for association with COMP. The recombinant catalytic domain and intact ADAMTS-7 are capable of digesting COMP in vitro. The enzymatic activity of ADAMTS-7 requires the presence of Zn2+ and appropriate pH (7.5-9.5), and the concentration of ADAMTS-7 in cartilage and synovium of patients with rheumatoid arthritis is significantly increased as compared to normal cartilage and synovium. ADAMTS-7 is the first metalloproteinase found to bind directly to and degrade COMP.

Purification of an insect derived recombinant human ADAMTS-1 reveals novel gelatin (type I collagen) degrading activities

ADAMTS-1 (A Disintegrin And Metalloprotease with ThromboSpondin repeats) is a member of a family of secreted proteolytic enzymes with a complex modular structure. These enzymes are characterised by an N-terminal metalloproteinase domain, a disintegrin-like domain and a carboxyl terminal region containing variable numbers of a repeat sequence with homology to thrombospondin-1. The expression of the gene for ADAMTS-1 has been associated with inflammation, ovulation, angiogenesis, cellular proliferation and bone formation. ADAMTS-1 can proteolytically process large proteoglycans indicating a potential role in extracellular matrix turnover. In this study, we have tested ADAMTS-1 activity in gelatin zymogram assays. Since previous data demonstrate that ADAMTS-1 is a matrix metalloproteinase (MMP) substrate and is highly unstable in conditioned medium from eukaryotic cell types, we created an insect cell line expressing human ADAMTS-1. We isolated an epitope tagged full-length recombinant ADAMTS-1 from serum free insect cell conditioned medium. The purified protein had aggrecanase activity and appears as two major bands on the silver stained SDS-PAGE corresponding well to a pro-domain on form of 115 kDa and a pro-domain off form of 90 kDa. Using denatured type I collagen in zymographic analysis we demonstrate that ADAMTS-1 has a previously unreported gelatinolytic activity. Also, we notice that processing of its C-terminal region by an apparently autocatalytic process reveals a 27 kDa species with gelatinolytic activity. Furthermore, we show that MMP2 but not MMP13 remove ADAMTS-1 specific gelatin zymopraphic zones.

Matrix-degrading proteases ADAMTS4 and ADAMTS5 (disintegrins and metalloproteinases with thrombospondin motifs 4 and 5) are expressed in human glioblastomas

Brain tumors, in particular glioblastomas, have a high morbidity and mortality, mainly due to their invasive nature. A prerequisite for this invasiveness is cell migration based on increased expression of proteases digesting the extracellular matrix. Brevican, an important extracellular proteoglycan that is upregulated in glioblastomas, can be degraded by certain proteases. We demonstrate that in human glioblastomas secretory proteases like ADAMTS4 and ADAMTS5 (aggrecanases 1 and 2; ADAMTS = a disintegrin and metalloproteinase with thrombospondin motifs) are expressed on the mRNA and protein levels in considerable amounts. Real-time RT-PCR shows a higher levels of ADAMTS4 and 5 expressions in glioblastomas in situ, compared to cultured human glioblastoma cells. The upregulation of these proteases in vivo by cytokines may explain this difference. In vitro, transforming growth factor-beta induces ADAMTS4, but less ADAMTS5, and interleukin-1beta ADAMTS5, but not ADAMTS4. As demonstrated by immunohistochemistry and confocal microscopy in situ, ADAMTS5 expression is confined to proliferating glioblastoma cells of surgical tumor sections and with lower intensity to astroglial cells in normal brain sections, as opposed to brevican. In vitro, glioblastoma-derived ADAMTS5 degrades recombinant human brevican to several smaller fragments. Our results show that ADAMTS4 and 5 are upregulated on proliferating glioblastoma cells and these proteases may contribute to their invasive potential.

Analysis of full length ADAMTS6 transcript reveals alternative splicing and a role for the 5' untranslated region in translational control

The ADAMTS (A Disintegrin and metalloproteinase with thrombospondin-1 type repeats) family of enzymes have been implicated in turnover of extracellular matrix. We previously showed that levels of ADAMTS6 mRNA in ARPE-19 cells were markedly increased following treatment with tumour necrosis factor alpha (TNFalpha). This study shows that the ADAMTS6 transcript contains unusually large untranslated regions (UTRs) at both the 5' and 3'end. The 5'UTR contains 11 AUG codons upstream of the predicted ADAMTS6 start codon and potently inhibits translation of a downstream reporter gene. However some translation can be restored by truncating the 5'UTR from the 5'end. The 5'UTR was tested for internal ribosome entry site activity using a bicistronic luciferase reporter plasmid, but none was detected. Using the 5' and 3'UTR sequences to screen the GenBank database we identified a full length ADAMTS6 cDNA of 7262 bp. This transcript is alternatively spliced at the 3'end of the open reading frame (ORF), resulting in an extended ORF containing 3 additional tsp-1 type repeats. Quantitative RT-PCR showed that the long and short form of the ADAMTS6 ORF are co-expressed in ARPE-19 cells, but the relative levels of the two forms is modulated by TNFalpha. The region of the transcript encoding the catalytic domain also contains several notable differences compared to the previously published ADAMTS6 cDNA sequence, including a redefinition of the predicted active site motif.

Peptidyl-Lys metalloendopeptidase-catalyzed 18O labeling for comparative proteomics: application to cytokine/lipolysaccharide-treated human retinal pigment epithelium cell line

We recently proposed a comparative proteomic method utilizing proteolytic 18O labeling of peptides catalyzed by peptidyl-Lys metalloendopeptidase (Lys-N) (Rao, K. C. S., Carruth, R. T., and Miyagi, M. (2005) Proteolytic 18O labeling by peptidyl-Lys metalloendopeptidase for comparative proteomics. J. Proteome Res. 4, 507-514). Unlike trypsin, which generates a mixture of isotopic isoforms resulting from the incorporation of one or two 18O atoms into each peptide species, Lys-N incorporates only a single 18O atom into the carboxyl terminus of each proteolytically generated peptide in H2(18)O solvent. This study reports the first biological application of the Lys-N-based proteolytic 18O labeling method, characterizing the proteome changes of cytokine/lipopolysaccharide-treated verses untreated human retinal pigment epithelium (ARPE-19) cells. The study resulted not only in the identification of 584 proteins but also the determination of the relative abundances of 562 proteins in the two proteomes. The results demonstrate the usefulness of the Lys-N-based proteolytic 18O labeling method in comparative proteomic studies. The results also provide the most comprehensive description of the retinal pigment epithelium proteome to date.

ADAMTS proteinases: a multi-domain, multi-functional family with roles in extracellular matrix turnover and arthritis

Members of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family are known to influence development, angiogenesis, coagulation and progression of arthritis. As proteinases their substrates include the von Willebrand factor precursor and extracellular matrix components such as procollagen, hyalectans (hyaluronan-binding proteoglycans including aggrecan), decorin, fibromodulin and cartilage oligomeric matrix protein. ADAMTS levels and activities are regulated at multiple levels through the control of gene expression, mRNA splicing, protein processing and inhibition by TIMP (tissue inhibitor of metalloproteinases). A recent screen of human cartilage has shown that multiple members of the ADAMTS family may be important in connective tissue homeostasis and pathology.

ADAMTS-9 is synergistically induced by interleukin-1β and tumor necrosis factor α in OUMS-27 chondrosarcoma cells and in human chondrocytes

OBJECTIVE

To compare induction of the aggrecanases (ADAMTS-1, ADAMTS-4, ADAMTS-5, ADAMTS-8, ADAMTS-9, and ADAMTS-15) by interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNFalpha) in chondrocyte-like OUMS-27 cells and human chondrocytes, and to determine the mechanism of induction of the most responsive aggrecanase gene.

METHODS

OUMS-27 cells were stimulated for different periods of time and with various concentrations of IL-1beta and/or TNFalpha. Human chondrocytes obtained from osteoarthritic joints and human skin fibroblasts were also stimulated with IL-1beta and/or TNFalpha. Total RNA was extracted, reverse transcribed, and analyzed by quantitative real-time polymerase chain reaction and Northern blotting. ADAMTS-9 protein was examined by Western blotting, and the role of the MAPK signaling pathway for ADAMTS9 induction in IL-1beta-stimulated OUMS-27 cells was investigated.

RESULTS

IL-1beta increased messenger RNA (mRNA) levels of ADAMTS4, ADAMTS5, and ADAMTS9 but not ADAMTS1 and ADAMTS8. The fold increase for ADAMTS9 mRNA was greater than that for mRNA of the other aggrecanase genes. The increase of ADAMTS9 mRNA by IL-1beta stimulation was greater in chondrocytes than in fibroblasts. The combination of IL-1beta and TNFalpha had a synergistic effect, resulting in a considerable elevation in the level of ADAMTS9 mRNA. ADAMTS-9 protein was also induced in IL-1beta-stimulated OUMS-27 cells. The MAPK inhibitors SB203580 and PD98059 decreased ADAMTS9 up-regulation in OUMS-27 cells.

CONCLUSION

ADAMTS9 is an IL-1beta- and TNFalpha-inducible gene that appears to be more responsive to these proinflammatory cytokines than are other aggrecanase genes. Furthermore, these cytokines had a synergistic effect on ADAMTS9. Together with the known ability of ADAMTS-9 to proteolytically degrade aggrecan and its potential to cleave other cartilage molecules, the data suggest that ADAMTS-9 may have a pathologic role in arthritis.

Functional evolution of ADAMTS genes: evidence from analyses of phylogeny and gene organization

Background

The ADAMTS (A Disintegrin-like and Metalloprotease with Thrombospondin motifs) proteins are a family of metalloproteases with sequence similarity to the ADAM proteases, that contain the thrombospondin type 1 sequence repeat motifs (TSRs) common to extracellular matrix proteins. ADAMTS proteins have recently gained attention with the discovery of their role in a variety of diseases, including tissue and blood disorders, cancer, osteoarthritis, Alzheimer's and the genetic syndromes Weill-Marchesani syndrome (ADAMTS10), thrombotic thrombocytopenic purpura (ADAMTS13), and Ehlers-Danlos syndrome type VIIC (ADAMTS2) in humans and belted white-spotting mutation in mice (ADAMTS20).

Results

Phylogenetic analysis and comparison of the exon/intron organization of vertebrate (Homo, Mus, Fugu), chordate (Ciona) and invertebrate (Drosophila and Caenorhabditis) ADAMTS homologs has elucidated the evolutionary relationships of this important gene family, which comprises 19 members in humans.

Conclusions

The evolutionary history of ADAMTS genes in vertebrate genomes has been marked by rampant gene duplication, including a retrotransposition that gave rise to a distinct ADAMTS subfamily (ADAMTS1, -4, -5, -8, -15) that may have distinct aggrecanase and angiogenesis functions.

ADAMTS7B, the full-length product of the ADAMTS7 gene, is a chondroitin sulfate proteoglycan containing a mucin domain

We have characterized ADAMTS7B, the authentic full-length protein product of the ADAMTS7 gene. ADAMTS7B has a domain organization similar to that of ADAMTS12, with a total of eight thrombospondin type 1 repeats in its ancillary domain. Of these, seven are arranged in two distinct clusters that are separated by a mucin domain. Unique to the ADAMTS family, ADAMTS7B is modified by attachment of the glycosaminoglycan chondroitin sulfate within the mucin domain, thus rendering it a proteoglycan. Glycosaminoglycan addition has potentially important implications for ADAMTS7B cellular localization and for substrate recognition. Although not an integral membrane protein, ADAMTS7B is retained near the cell surface of HEK293F cells via interactions involving both the ancillary domain and the prodomain. ADAMTS7B undergoes removal of the prodomain by a multistep furin-dependent mechanism. At least part of the final processing event, i.e. cleavage following Arg(220) (mouse sequence annotation), occurs at the cell surface. ADAMTS7B is an active metalloproteinase as shown by its ability to cleave alpha(2)-macroglobulin, but it does not cleave specific peptide bonds in versican and aggrecan attacked by ADAMTS proteases. Together with ADAMTS12, whose primary structure also predicts a mucin domain, ADAMTS7B constitutes a unique subgroup of the ADAMTS family.

The expression of native and cultured RPE grown on different matrices

The purpose of this work was to determine the expression profiles of retinal pigment epithelial (RPE) cells grown on different matrices and to assess the degree of culture-induced artifact by comparing the profiles to native RPE. Visually confluent ARPE-19 cells were grown on plastic, Matrigel, collagen I, collagen IV, laminin, and fibronectin for 1 wk, and serum was withdrawn for 3 days. Morphologically normal, macular RPE cells were laser-capture microdissected from three human eye globes. Total RNA was extracted from 5,000 cells and reverse transcribed, and radiolabeled cDNA probes were hybridized to an array containing 4,325 known genes. Arrays were assessed by cluster analysis and significance analysis of microarrays (SAM). Real-time RT-PCR was used to validate differentially expressed genes. Despite similar morphology, ARPE-19 demonstrated different expression profiles when grown on different matrices. Cluster analysis showed that cells grown on collagen IV, laminin, and fibronectin had similar profiles that were distinct from cells grown on collagen I. Cells grown on plastic clustered closest to native RPE. This expression pattern was confirmed with supervised cluster analyses. The number of differentially expressed genes, function of differentially expressed genes, and profile of expressed and unexpressed genes suggest that the overall expression profile of cultured cells is significantly different from native RPE. RPE cells grown on collagen IV, laminin, and fibronectin have profiles more similar than cells grown on plastic, Matrigel, or collagen I. The overall mRNA phenotype, however, is different from morphologically normal, native macular RPE.