CHU de Montpellier. Laboratoire de Génétique Moléculaire. IURC, Institut Universitaire de Recherche Clinique. UFR Médecine Site NORD UPM/IURC. 640 Avenue du Doyen Giraud 34093 MONTPELLIER Cedex 5
Abstract: Optimal management, including timing of surgery, remains debated in Marfan syndrome because of a lack of data on aortic risk associated with this disease.
Abstract: Mutations in the dysferlin gene (DYSF) lead to a complete or partial absence of the dysferlin protein in skeletal muscles and are at the origin of dysferlinopathies, a heterogeneous group of rare autosomal recessive inherited neuromuscular disorders. As a step towards a better understanding of the DYSF mutational spectrum, and towards possible inclusion of patients in future therapeutic clinical trials, we set up the Universal Mutation Database for Dysferlin (UMD-DYSF), a Locus-Specific Database developed with the UMD® software. The main objective of UMD-DYSF is to provide an updated compilation of mutational data and relevant interactive tools for the analysis of DYSF sequence variants, for diagnostic and research purposes. In particular, specific algorithms can facilitate the interpretation of newly identified intronic, missense- or isosemantic-exonic sequence variants, a problem encountered recurrently during genetic diagnosis in dysferlinopathies. UMD-DYSF v1.0 is freely accessible at www.umd.be/DYSF/. It contains a total of 742 mutational entries corresponding to 266 different disease-causing mutations identified in 558 patients worldwide diagnosed with dysferlinopathy. This article presents for the first time a comprehensive analysis of the dysferlin mutational spectrum based on all compiled DYSF disease-causing mutations reported in the literature to date, and using the main bioinformatics tools offered in UMD-DYSF.
Abstract: ABSTRACT: BACKGROUND: Clinical features, complications and treatments of Gaucher's disease (GD), a rare autosomal--recessive disorder due to a confirmed lysosomal enzyme (glucocerebrosidase) deficiency, are described. METHODS: All patients with known GD, living in France, with >=1 consultations (1980--2010), were included in the French GD registry, yielding the following 4 groups: the entire cohort, with clinical description; and its subgroups: patients with >=1 follow-up visits, to investigate complications; recently followed (2009--2010) patients; and patients treated during 2009--2010, to examine complications before and during treatment. Data are expressed as medians (range) for continuous variables and numbers (%) for categorical variables. RESULTS: Among the 562 registry patients, 265 (49.6%) were females; 454 (85.0%) had type 1, 22 (4.1%) type 2, 37 (6.9%) perinatal--lethal type and 21 (3.9%) type 3. Median ages at first GD symptoms and diagnosis, respectively, were 15 (0--77) and 22 (0--84) years for all types. The first symptom diagnosing GD was splenomegaly and/or thrombocytopenia (37.6% and 26.3%, respectively). Bone-marrow aspiration and/or biopsy yielded the diagnosis for 54.7% of the patients, with enzyme deficiency confirming GD for all patients. Birth incidence rate was estimated at 1/50,000 and prevalence at 1/136,000. For the 378 followed patients, median follow-up was 16.2 (0.1--67.6) years. Major clinical complications were bone events (BE; avascular necrosis, bone infarct or pathological fracture) for 109 patients, splenectomy for 104, and Parkinson's disease for 14; 38 patients died (neurological complications for 15 type-2 and 3 type-3 patients, GD complications for 11 type-1 and another disease for 9 type-1 patients). Forty-six had monoclonal gammopathy. Among 283 recently followed patients, 36 were untreated and 247 had been treated during 2009--2010; 216 patients received treatment in December 2010 (126 with imiglucerase, 45 velaglucerase, 24 taliglucerase, 21 miglustat). BE occurred before (130 in 67 patients) and under treatment (60 in 41 patients) with respective estimated frequencies (95% CI) of first BE at 10 years of 20.3% (14.1%--26.5%) and 19.8% (13.5%--26.1%). CONCLUSION: This registry enabled the epidemiological description of GD in France and showed that BE occur even during treatment.
Abstract: The diagnosis of Marfan syndrome (MFS) is challenging and international criteria have been proposed. The 1996 Ghent criteria were adopted worldwide, but new diagnostic criteria for MFS were released in 2010, giving more weight to aortic root aneurysm and ectopia lentis. We aimed to compare the diagnosis reached by applying this new nosology vs the Ghent nosology in a well-known series of 1009 probands defined by the presence of an FBN1 mutation. A total of 842 patients could be classified as MFS according to the new nosology (83%) as compared to 894 (89%) according to the 1996 Ghent criteria. The remaining 17% would be classified as ectopia lentis syndrome (ELS), mitral valve prolapse syndrome or mitral valve, aorta, skeleton and skin (MASS) syndrome, or potential MFS in patients aged less than 20 years. Taking into account the median age at last follow-up (29 years), the possibility has to be considered that these patients would go on to develop classic MFS with time. Although the number of patients for a given diagnosis differed only slightly, the new nosology led to a different diagnosis in 15% of cases. Indeed, 10% of MFS patients were reclassified as ELS or MASS in the absence of aortic dilatation; conversely, 5% were reclassified as MFS in the presence of aortic dilatation. The nosology is easier to apply because the systemic score is helpful to reach the diagnosis of MFS only in a minority of patients. Diagnostic criteria should be a flexible and dynamic tool so that reclassification of patients with alternative diagnosis is possible, requiring regular clinical and aortic follow-up.
Abstract: To better characterize patients with Marfan syndrome who have survived an acute aortic dissection and to estimate the risks of events in the descending aorta. Up until now, this portion of the aorta has not been well studied but is gaining importance due to improved patient survival.
Abstract: Analysis of the literature reporting p53 mutations shows that 8% of report display typographical mistakes with a notable increase in recent years. These errors are sometimes isolated, but in some cases, they concern several or even all mutations described in a single article. Furthermore, some works report unusual profile of p53 mutations whose accuracy is difficult to assess. To handle these problems we have developed MUT-TP53 2.0, an accurate and powerful tool that will automatically handle p53 mutations and generate tables ready for publication that will lower the risk of typographical errors. Furthermore, using functional and statistical information issued from the UMD p53 database, it allows to assess the biological activity and the likelihood of every p53 mutant.
Abstract: New technologies, which constantly become available for mutation detection and gene analysis, have contributed to an exponential rate of discovery of disease genes and variation in the human genome. The task of collecting and documenting this enormous amount of data in genetic databases represents a major challenge for the future of biological and medical science. The Locus Specific Databases (LSDBs) are so far the most efficient mutation databases. This review presents the main types of databases available for the analysis of mutations responsible for genetic disorders, as well as open perspectives for new therapeutic research or challenges for future medicine. Accurate and exhaustive collection of variations in human genomes will be crucial for research and personalized delivery of healthcare.
Abstract: With the increasing knowledge of cystic fibrosis (CF) and CFTR-related diseases (CFTR-RD), the number of sequence variations in the CFTR gene is constantly raising. CF and particularly CFTR-RD provide a particular challenge because of many unclassified variants and identical genotypes associated with different phenotypes. Using the Universal Mutation Database (UMD) software we have constructed UMD-CFTR (freely available at the URL: http://www.umd.be/CFTR/), the first comprehensive relational CFTR database that allows an in-depth analysis and annotation of all variations identified in individuals whose CFTR genes have been analyzed extensively. The system has been tested on the molecular data from 757 patients (540 CF and 217 CBAVD) including disease-causing, unclassified, and nonpathogenic alterations (301 different sequence variations) representing 3,973 entries. Tools are provided to assess the pathogenicity of mutations. UMD-CFTR also offers a number of query tools and graphical views providing instant access to the list of mutations, their frequencies, positions and predicted consequences, or correlations between genotypes, haplotypes, and phenotypes. UMD-CFTR offers a way to compile not only disease-causing genotypes but also haplotypes. It will help the CFTR scientific and medical communities to improve sequence variation interpretation, evaluate the putative influence of haplotypes on mutations, and correlate molecular data with phenotypes.
Abstract: Approximately half of gene lesions responsible for human inherited diseases are due to an amino acid substitution, showing that this mutational mechanism plays a large role in diseases. Distinguishing neutral sequence variations from those responsible for the phenotype is of major interest in human genetics. Because in vitro validation of mutations is not always possible in diagnostic settings, indirect arguments must be accumulated to define whether a missense variation is causative. To further differentiate neutral variants from pathogenic nucleotide substitutions, we developed a new tool, UMD-Predictor. This tool provides a combinatorial approach that associates the following data: localization within the protein, conservation, biochemical properties of the mutant and wild-type residues, and the potential impact of the variation on mRNA. To evaluate this new tool, we compared it to the SIFT, PolyPhen, and SNAP software, the BLOSUM62 and Yu's Biochemical Matrices. All tools were evaluated using variations from well-validated datasets extracted from four UMD-LSDB databases (UMD-FBN1, UMD-FBN2, UMD-TGFBR1, and UMD-TGFBR2) that contain all published mutations of the corresponding genes, that is, 1,945 mutations, among which 796 different substitutions corresponding to missense mutations. Our results show that the UMD-Predictor algorithm is the most efficient tool to predict pathogenic mutations in this context with a positive predictive value of 99.4%, a sensitivity of 95.4%, and a specificity of 92.2%. It can thus enhance the interpretation of variations in these genes, and could easily be applied to any other disease gene through the freely available UMD generic software (http://www.umd.be).
Abstract: UMD-DMD France is a knowledgebase developed through a multicenter academic effort to provide an up-to-date resource of curated information covering all identified mutations in patients with a dystrophinopathy. The current release includes 2,411 entries consisting in 2,084 independent mutational events identified in 2,046 male patients and 38 expressing females, which corresponds to an estimated number of 39 people per million with a genetic diagnosis of dystrophinopathy in France. Mutations consist in 1,404 large deletions, 215 large duplications, and 465 small rearrangements, of which 39.8% are nonsense mutations. The reading frame rule holds true for 96% of the DMD patients and 93% of the BMD patients. Quality control relies on the curation by four experts for the DMD gene and related diseases. Data on dystrophin and RNA analysis, phenotypic groups, and transmission are also available. About 24% of the mutations are de novo events. This national centralized resource will contribute to a greater understanding of prevalence of dystrophinopathies in France, and in particular, of the true frequency of BMD, which was found to be almost half (43%) that of DMD. UMD-DMD is a searchable anonymous database that includes numerous newly developed tools, which can benefit to all the scientific community interested in dystrophinopathies. Dedicated functions for genotype-based therapies allowed the prediction of a new multiexon skipping (del 45-53) potentially applicable to 53% of the deleted DMD patients. Finally, such a national database will prove to be useful to implement the international global DMD patients' registries under development.
Abstract: Thousands of mutations are identified yearly. Although many directly affect protein expression, an increasing proportion of mutations is now believed to influence mRNA splicing. They mostly affect existing splice sites, but synonymous, non-synonymous or nonsense mutations can also create or disrupt splice sites or auxiliary cis-splicing sequences. To facilitate the analysis of the different mutations, we designed Human Splicing Finder (HSF), a tool to predict the effects of mutations on splicing signals or to identify splicing motifs in any human sequence. It contains all available matrices for auxiliary sequence prediction as well as new ones for binding sites of the 9G8 and Tra2-beta Serine-Arginine proteins and the hnRNP A1 ribonucleoprotein. We also developed new Position Weight Matrices to assess the strength of 5' and 3' splice sites and branch points. We evaluated HSF efficiency using a set of 83 intronic and 35 exonic mutations known to result in splicing defects. We showed that the mutation effect was correctly predicted in almost all cases. HSF could thus represent a valuable resource for research, diagnostic and therapeutic (e.g. therapeutic exon skipping) purposes as well as for global studies, such as the GEN2PHEN European Project or the Human Variome Project.
Abstract: Congenital contractural arachnodactyly (CCA) is an extremely rare disease, due to mutations in the FBN2 gene encoding fibrillin-2. Another member of the fibrillin family, the FBN1 gene, is involved in a broad phenotypic continuum of connective-tissue disorders including Marfan syndrome. Identifying not only what is in common but also what differentiates these two proteins should enable us to better comprehend their respective functions and better understand the multitude of diseases in which these two genes are involved. In 1995 we created a locus-specific database (LSDB) for FBN1 mutations with the Universal Mutation Database (UMD) tool. To facilitate comparison of identified mutations in these two genes and search for specific functional areas, we created an LSDB for the FBN2 gene: the UMD-FBN2 database. This database lists 26 published and six newly identified mutations that mainly comprise missense and splice-site mutations. Although the number of described FBN2 mutations was low, the frequency of joint dislocation was significantly higher with missense mutations when compared to splice site mutations.
Abstract: The implication of mutations in the TGFBR2 gene, known to be involved in cancers, in Marfan syndrome (MFS) and later in Loeys-Dietz syndrome (LDS) and Familial Thoracic Aortic Aneurysms and Dissections (TAAD2) gives a new example of the complexity of one gene involved in multiple diseases. To date, known TGFBR2 mutations are not disease-specific and many mutations have to be accumulated before genotype-phenotype relationships emerge. To facilitate mutational analysis of the TGFBR2 gene, a locus-specific database has been set up with the Universal Mutation Database (UMD) software. The version of the computerized database contains 85 entries. A total of 12 mutations are reported to be involved in MFS, six in incomplete MFS, 30 in LDS type I, 10 in LDS type II, seven in TAAD2, and 20 in various cancers. The database is accessible online at http://www.umd.be (last accessed: 3 July 2007).
Abstract: Using the Universal Mutation Database (UMD) software, we have constructed "UMD-USHbases", a set of relational databases of nucleotide variations for seven genes involved in Usher syndrome (MYO7A, CDH23, PCDH15, USH1C, USH1G, USH3A and USH2A). Mutations in the Usher syndrome type I causing genes are also recorded in non-syndromic hearing loss cases and mutations in USH2A in non-syndromic retinitis pigmentosa. Usher syndrome provides a particular challenge for molecular diagnostics because of the clinical and molecular heterogeneity. As many mutations are missense changes, and all the genes also contain apparently non-pathogenic polymorphisms, well-curated databases are crucial for accurate interpretation of pathogenicity. Tools are provided to assess the pathogenicity of mutations, including conservation of amino acids and analysis of splice-sites. Reference amino acid alignments are provided. Apparently non-pathogenic variants in patients with Usher syndrome, at both the nucleotide and amino acid level, are included. The UMD-USHbases currently contain more than 2,830 entries including disease causing mutations, unclassified variants or non-pathogenic polymorphisms identified in over 938 patients. In addition to data collected from 89 publications, 15 novel mutations identified in our laboratory are recorded in MYO7A (6), CDH23 (8), or PCDH15 (1) genes. Information is given on the relative involvement of the seven genes, the number and distribution of variants in each gene. UMD-USHbases give access to a software package that provides specific routines and optimized multicriteria research and sorting tools. These databases should assist clinicians and geneticists seeking information about mutations responsible for Usher syndrome.
Abstract: Approximately two-thirds of Duchenne muscular dystrophy (DMD) patients show intragenic deletions ranging from one to several exons of the DMD gene and leading to a premature stop codon. Other deletions that maintain the translational reading frame of the gene result in the milder Becker muscular dystrophy (BMD) form of the disease. Thus the opportunity to transform a DMD phenotype into a BMD phenotype appeared as a new treatment strategy with the development of antisense oligonucleotides technology, which is able to induce an exon skipping at the pre-mRNA level in order to restore an open reading frame. Because the DMD gene contains 79 exons, thousands of potential transcripts could be produced by exon skipping and should be investigated. The conventional approach considers skipping of a single exon. Here we report the comparison of single- and multiple-exon skipping strategies based on bioinformatic analysis. By using the Universal Mutation Database (UMD)-DMD, we predict that an optimal multiexon skipping leading to the del45-55 artificial dystrophin (c.6439_8217del) could transform the DMD phenotype into the asymptomatic or mild BMD phenotype. This multiple-exon skipping could theoretically rescue up to 63% of DMD patients with a deletion, while the optimal monoskipping of exon 51 would rescue only 16% of patients.
Abstract: Mutation of the p53 gene is the most frequent genetic alteration found in human cancer, but it is also the most frequently reported with more than 22,000 mutations published in 2,000 papers. In 1991, we developed a database and software to handle and analyze all this information. The database has been widely used for clinical analysis and molecular epidemiology. We have expanded the scope of the database by integrating structural, phylogenetic and biological information on wild-type (wt) and mutant TP53. Integration of the TP53 mutant activity database provides unique information that will be useful to both clinicians and scientists. All of this information is available from a new website (www.umd.be:2072/) that will generate a detailed informative page for every TP53 mutant in the database. New tools to check TP53 mutations and minimize errors found in the literature are also available.
Abstract: Analyses of the pattern of p53 mutations have been essential for epidemiologic studies linking carcinogen exposure and cancer. We were concerned by the inclusion of dubious reports in the p53 databases that could lead to controversial analysis prejudicial to the scientific community.
Abstract: With the completion of the Human Genome Project, our vision of human genetic diseases has changed. The cloning of new disease-causing genes can now be performed in silico, and thousands of mutations are being identified in diagnostic and research laboratories yearly. Knowledge about these mutations and their association with clinical and biological data is essential for clinicians, geneticists, and researchers. To collect and analyze these data, we developed a generic software called Universal Mutation Databases (UMD) to create locus-specific databases. Here we report the new release (September 2004) of this freely available tool (www.umd.be), which allows the creation of LSDBs for virtually any gene and includes a large set of new analysis tools. We have implemented new features to integrate noncoding sequences, clinical data, pictures, monoclonal antibodies, and polymorphic markers (SNPs). Today the UMD retains all specifically designed tools to analyze mutations at the molecular level, as well as new sets of routines to search for genotype-phenotype correlations. We also created specific tools for infrequent mutations such as gross deletions and duplications, and deep intronic mutations. A large set of dedicated tools are now available for intronic mutations, including methods to calculate the consensus values (CVs) of potential splice sites and to search for exonic splicing enhancer (ESE) motifs. In addition, we have created specific routines to help researchers design new therapeutic strategies, such as exon skipping, aminoglycoside read-through of stop codons, or monoclonal antibody selection and epitope scanning for gene therapy.
Abstract: The study reported here characterizes the presence both of endothelin (ET) receptors and of a synthesizing ET apparatus in the human neuroblastoma SK-SY5Y cell line. We demonstrated, using reverse transcriptase polymerase chain reaction (RT-PCR), that these cells bound [125I]ET-1. The potency order of ET analogs to inhibit [125I]ET-1 binding was consistent with the presence of ET(A)-receptors. [Ca2+]i was increased by both ET-1 and ET-3 (potency order: ET-1 > ET-3. The mRNAs of preproendothelin-1 and of endothelin converting enzyme (ECE) were expressed by cells, as shown by RT-PCR studies. These mRNAs were translated into functional proteins as the cells were able to release mature (1-21) ET-like immunoreactivity into the culture medium. That secretion was time-dependent and was enhanced by treatment of the cells by the phorbol ester 12-O-tetradecanoyl phorbol-13-acetate. These results show that the human SK-SY5Y neuroblastoma cell line produces mature ET which could act as an autocrine/paracrine factor these cells.
Abstract: The aim of this investigation was to determine whether the endothelin receptor subtype of a megakaryoblastic cell line (MEG-01) changes during culture passages as cells undergo maturation and differentiation. On early-passage cells, binding of [125I]endothelin-1 was completely inhibited by 1 microM BQ 123 (cyclo-[D-tryptophanyl-D-aspartyl-prolyl-D-valyl-leucyl]), but not by sarafotoxin 6C. Also the endothelin-1-enhancing effect on [Ca2+]i was prevented by BQ 123, whereas sarafotoxin 6C had no effect on [Ca2+]i. In late-passage cells, endothelin ET(B) analogs, unlike endothelin ET(A) analogs, competed with binding of [125I]endothelin-1. Endothelin ET(B) receptor agonists increased [Ca2+]i while the endothelin-1-induced response was inhibited by BQ 788 ([N-[(2R,6S)-2,6-dimethyl-piperidinocarbonyl]-4-methyl-D-leucyl]-[ N(omega)-(methoxycarbonyl)-D-tryptophanyl]-D-norleucine), but not by BQ 123, although both endothelin ET(A) and ET(B) receptor mRNAs were expressed, as shown by reverse transcriptase-polymerase chain reaction. These results demonstrate that in MEG-01 cells switch from expression of endothelin ET(A) to expression of ET(B) receptors during culture. The data also suggest that late-passage MEG-01 cells look like platelets, in terms of endothelin receptor subtype.
Abstract: The human megakaryoblastic cell lines HEL, MEG-01, and DAMI express preproendothelin-1 mRNA. This investigation was designed to find out whether they could also express endothelin-converting enzyme (ECE) and release mature endothelin (ET). RT-PCR applied to RNA isolated from the cell lines amplified fragments of the expected size. The amplified cDNA of MEG-01 was submitted to restriction enzymes, which generated the expected subfragments. Membrane ECE activity was phosphoramidon-sensitive, in contrast to the cytosolic activity capable of producing ET-1 from big ET-1. The three cell lines produced ir-ET in a time-dependent manner. These results show that human megakaryoblastic cell lines express functional, phosphoramidon-sensitive and insensitive ECE activity and produce mature ET.
Abstract: Endothelin-1 (ET-1) is involved in adrenal steroid secretion but its cell origin remains unclear. We showed, using RT-PCR the expression of the mRNAs for preproET-1 and ECE-1 in primary cultures of human adrenal cells enriched in glomerulosa cells. Since these expressions could be due to contamination of steroid secreting cells by other cells, we also used the human adrenocortical cell line H295R, which was shown to produce steroids. This cell line also expressed preproET-1-RNA and released mature ET. Functional ET receptors were shown on H295R and cultured human adrenocortical cells. These findings indicate that adrenal steroid-secreting cells synthesize and release ET-1, raising the possibility for an autocrine-paracrine effect of ET-1 on adrenocortical functions.
Abstract: Because it has been shown that human platelet precursors from normal bone marrow express preproendothelin-1 (ET-1) mRNA, this investigation was designed to find out whether these cells could synthesize and release mature ET-1 and express ET receptors. Therefore, we examined the expression of endothelin-converting enzyme (ECE) mRNA and of mRNAs for ET receptors in cells purified from normal bone marrow and measured immunoreactive (ir)ET in their culture medium. RT-PCR applied to RNAs from platelet precursors yielded amplified fragments of the expected sizes of 567, 428, and 299 bp for ECE, ETB and ETA receptors, respectively. These cells released ir-ET into the culture medium in a time-dependent fashion. These results raise the possibility of autocrine actions of the intrinsic ET system in bone marrow platelet precursor cells.
Abstract: The aim of the present investigation was to determine whether endothelin (ET) could be expressed in and released from the human leukemia megakaryoblastic cell lines HEL, MEG-01, DAMI and the normal human platelet progenitors. Using the reverse transcriptase-polymerase chain reaction (RT-PCR) on total RNA isolated from the cells, we amplified a cDNA of the expected size (453 bp). Southern-blotting hybridization revealed that RT-PCR products from the cell lines were specific of ET-1 mRNA. Immunocytochemical analyses highlighted immunoreactive ET-1 in the cytoplasm of these cells which also released the mature peptide. ET-1 release from the three cell lines was increased by thrombin exposure. Although MEG-01 cells express ET receptors, ET-1, the selective ETB agonist sarafotoxin 6C and the non-selective ET-receptor antagonist PD 142893 showed no proliferative or antiproliferative action in basal or stimulating medium. This indicated a lack of autocrine ET-mediated effect on growth. These results demonstrate for the first time that human megakaryoblastic leukemia cell lines and normal bone marrow platelet precursors express ET-1 mRNA and release the mature peptide.
Abstract: Endothelin binds to receptors belonging to the family of G-protein-coupled receptors with an N-terminal extracellular domain that is suspected to be part of the binding site. We have synthesized different peptides of this N-terminal extracellular domain and analyzed the increase in calcium concentration ([Ca2+]i) induced by these peptides in the MEG-01 cell line and their influence on the ET-1 concentration-effect response. Nt (20-79) exhibited a partial agonistic effect on [Ca2+]i and blunted the functional response of ET-1 in MEG-01 cells, but was not able to compete with radiolabeled ET-1 binding. The agonist effect was inhibited by the ET receptor antagonists PD 142893 and BQ123, suggesting an interaction between Nt (20-79) and the ETA receptor at a site that could be different from the one of ET-1.
Abstract: The presence of endothelin (ET) receptors and the nature of the subtype and expression of ET were investigated in the human megakaryoblastic cell line MEG-01. By the RT-PCR procedure, we have shown that both ETA and ETB receptor subtype mRNAs are expressed in the cells. However, binding experiments have shown that the selective ETB receptor antagonist BQ788, but not the selective ETA receptor antagonist BQ123, competes with the specific binding of [125I]ET-1. Using immunocytochemistry, RIA, and RT-PCR Southern blot, we have shown that MEG-01 cells express ET-1. In addition, ET (1-21)-like immunoreactivity was released from the cells into the culture medium, and this release was modulated by thrombin. These data suggest that an ET-1-mediated autocrine loop could occur in the human megakaryoblastic MEG-01 cell line.
