Publications by authors named "Nicodeme Paul"

32 Publications

Impact of Tenascin-C on Radiotherapy in a Novel Syngeneic Oral Squamous Cell Carcinoma Model With Spontaneous Dissemination to the Lymph Nodes.

Front Immunol 2021 5;12:636108. Epub 2021 Jul 5.

INSERM U1109-MN3T, The Microenvironmental Niche in Tumorigenesis and Targeted Therapy, Strasbourg, France.

Radiotherapy, the most frequent treatment of oral squamous cell carcinomas (OSCC) besides surgery is employed to kill tumor cells but, radiotherapy may also promote tumor relapse where the immune-suppressive tumor microenvironment (TME) could be instrumental. We established a novel syngeneic grafting model from a carcinogen-induced tongue tumor, OSCC13, to address the impact of radiotherapy on OSCC. This model revealed similarities with human OSCC, recapitulating carcinogen-induced mutations found in smoking associated human tongue tumors, abundant tumor infiltrating leukocytes (TIL) and, spontaneous tumor cell dissemination to the local lymph nodes. Cultured OSCC13 cells and OSCC13-derived tongue tumors were sensitive to irradiation. At the chosen dose of 2 Gy mimicking treatment of human OSCC patients not all tumor cells were killed allowing to investigate effects on the TME. By investigating expression of the extracellular matrix molecule tenascin-C (TNC), an indicator of an immune suppressive TME, we observed high local TNC expression and TIL infiltration in the irradiated tumors. In a TNC knockout host the TME appeared less immune suppressive with a tendency towards more tumor regression than in WT conditions. Altogether, our novel syngeneic tongue OSCC grafting model, sharing important features with the human OSCC disease could be relevant for future anti-cancer targeting of OSCC by radiotherapy and other therapeutic approaches.
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http://dx.doi.org/10.3389/fimmu.2021.636108DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8287883PMC
July 2021

Impairing flow-mediated endothelial remodeling reduces extravasation of tumor cells.

Sci Rep 2021 Jun 23;11(1):13144. Epub 2021 Jun 23.

Tumor Biomechanics, INSERM UMR_S1109, CRBS, 67000, Strasbourg, France.

Tumor progression and metastatic dissemination are driven by cell-intrinsic and biomechanical cues that favor the growth of life-threatening secondary tumors. We recently identified pro-metastatic vascular regions with blood flow profiles that are permissive for the arrest of circulating tumor cells. We have further established that such flow profiles also control endothelial remodeling, which favors extravasation of arrested CTCs. Yet, how shear forces control endothelial remodeling is unknown. In the present work, we aimed at dissecting the cellular and molecular mechanisms driving blood flow-dependent endothelial remodeling. Transcriptomic analysis of endothelial cells revealed that blood flow enhanced VEGFR signaling, among others. Using a combination of in vitro microfluidics and intravital imaging in zebrafish embryos, we now demonstrate that the early flow-driven endothelial response can be prevented upon specific inhibition of VEGFR tyrosine kinase and subsequent signaling. Inhibitory targeting of VEGFRs reduced endothelial remodeling and subsequent metastatic extravasation. These results confirm the importance of VEGFR-dependent endothelial remodeling as a driving force of CTC extravasation and metastatic dissemination. Furthermore, the present work suggests that therapies targeting endothelial remodeling might be a relevant clinical strategy in order to impede metastatic progression.
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http://dx.doi.org/10.1038/s41598-021-92515-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8222393PMC
June 2021

Tenascin-C immobilizes infiltrating T lymphocytes through CXCL12 promoting breast cancer progression.

EMBO Mol Med 2021 Jun 14;13(6):e13270. Epub 2021 May 14.

The Tumor Microenvironment Laboratory, INSERM UMR_S 1109, Faculté de Médecine, Hopital Civil, Institut d'Hématologie et d'Immunologie, Strasbourg, France.

Immune checkpoint therapy, where CD8 tumor infiltrating T lymphocytes (TIL) are reactivated, is a promising anti-cancer treatment approach, yet with low response rates. The extracellular matrix, in particular tenascin-C, may generate barriers for TIL. To investigate this possibility, we used a MMTV-NeuNT and syngeneic mammary gland grafting model derived thereof with engineered tenascin-C levels and observed accumulation of CD8 TIL in tenascin-C-rich stroma. Inhibition studies revealed that tenascin-C induced CXCL12 through TLR4. By binding CXCL12, tenascin-C retained CD8 TIL in the stroma. Blockade of CXCR4, the receptor of CXCL12, enhanced macrophage and CD8 TIL infiltration and reduced tumor growth and subsequent metastasis. Retention of CD8 TIL by tenascin-C/CXCL12 was also observed in human breast cancer by tissue staining. Moreover, whereas high CD8 TIL numbers correlated with longer metastasis-free survival, this was not the case when also tenascin-C and CXCL12 levels were high. Altogether, these results may be useful for improving tumor immunity as diagnostic tool and to formulate a future "TIL-matrix-release-and-reactivate" strategy.
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http://dx.doi.org/10.15252/emmm.202013270DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8185552PMC
June 2021

Temporal multiomic modeling reveals a B-cell receptor proliferative program in chronic lymphocytic leukemia.

Leukemia 2021 05 8;35(5):1463-1474. Epub 2021 Apr 8.

Laboratoire d'ImmunoRhumatologie Moléculaire, INSERM UMR-S1109, LabEx Transplantex, Plateforme Genomax, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France.

B-cell receptor (BCR) signaling is crucial for the pathophysiology of most mature B-cell lymphomas/leukemias and has emerged as a therapeutic target whose effectiveness remains limited by the occurrence of mutations. Therefore, deciphering the cellular program activated downstream this pathway has become of paramount importance for the development of innovative therapies. Using an original ex vivo model of BCR-induced proliferation of chronic lymphocytic leukemia cells, we generated 108 temporal transcriptional and proteomic profiles from 1 h up to 4 days after BCR activation. This dataset revealed a structured temporal response composed of 13,065 transcripts and 4027 proteins, comprising a leukemic proliferative signature consisting of 430 genes and 374 proteins. Mathematical modeling of this complex cellular response further highlighted a transcriptional network driven by 14 early genes linked to proteins involved in cell proliferation. This group includes expected genes (EGR1/2, NF-kB) and genes involved in NF-kB signaling modulation (TANK, ROHF) and immune evasion (KMO, IL4I1) that have not yet been associated with leukemic cells proliferation. Our study unveils the BCR-activated proliferative genetic program in primary leukemic cells. This approach combining temporal measurements with modeling allows identifying new putative targets for innovative therapy of lymphoid malignancies and also cancers dependent on ligand-receptor interactions.
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http://dx.doi.org/10.1038/s41375-021-01221-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8102193PMC
May 2021

Ral GTPases promote breast cancer metastasis by controlling biogenesis and organ targeting of exosomes.

Elife 2021 Jan 6;10. Epub 2021 Jan 6.

INSERM UMR_S1109, Tumor Biomechanics, Strasbourg, France.

Cancer extracellular vesicles (EVs) shuttle at distance and fertilize pre-metastatic niches facilitating subsequent seeding by tumor cells. However, the link between EV secretion mechanisms and their capacity to form pre-metastatic niches remains obscure. Using mouse models, we show that GTPases of the Ral family control, through the phospholipase D1, multi-vesicular bodies homeostasis and tune the biogenesis and secretion of pro-metastatic EVs. Importantly, EVs from RalA or RalB depleted cells have limited organotropic capacities and are less efficient in promoting metastasis. RalA and RalB reduce the EV levels of the adhesion molecule MCAM/CD146, which favors EV-mediated metastasis by allowing EVs targeting to the lungs. Finally, RalA, RalB, and MCAM/CD146, are factors of poor prognosis in breast cancer patients. Altogether, our study identifies RalGTPases as central molecules linking the mechanisms of EVs secretion and cargo loading to their capacity to disseminate and induce pre-metastatic niches in a CD146-dependent manner.
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http://dx.doi.org/10.7554/eLife.61539DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7822591PMC
January 2021

NCKAP1L defects lead to a novel syndrome combining immunodeficiency, lymphoproliferation, and hyperinflammation.

J Exp Med 2020 12;217(12)

Department of Pediatrics, King Abdulaziz Medical City, King Abdullah Specialized Children's Hospital, Riyadh, Saudi Arabia.

The Nck-associated protein 1-like (NCKAP1L) gene, alternatively called hematopoietic protein 1 (HEM-1), encodes a hematopoietic lineage-specific regulator of the actin cytoskeleton. Nckap1l-deficient mice have anomalies in lymphocyte development, phagocytosis, and neutrophil migration. Here we report, for the first time, NCKAP1L deficiency cases in humans. In two unrelated patients of Middle Eastern origin, recessive mutations in NCKAP1L abolishing protein expression led to immunodeficiency, lymphoproliferation, and hyperinflammation with features of hemophagocytic lymphohistiocytosis. Immunophenotyping showed an inverted CD4/CD8 ratio with a major shift of both CD4+ and CD8+ cells toward memory compartments, in line with combined RNA-seq/proteomics analyses revealing a T cell exhaustion signature. Consistent with the core function of NCKAP1L in the reorganization of the actin cytoskeleton, patients' T cells displayed impaired early activation, immune synapse morphology, and leading edge formation. Moreover, knockdown of nckap1l in zebrafish led to defects in neutrophil migration. Hence, NCKAP1L mutations lead to broad immune dysregulation in humans, which could be classified within actinopathies.
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http://dx.doi.org/10.1084/jem.20192275DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7526481PMC
December 2020

Tenascin-C Orchestrates an Immune-Suppressive Tumor Microenvironment in Oral Squamous Cell Carcinoma.

Cancer Immunol Res 2020 09 14;8(9):1122-1138. Epub 2020 Jul 14.

Université Côte d'Azur, CNRS, IPMC, Valbonne-Sophia Antipolis, France.

Inherent immune suppression represents a major challenge in the treatment of human cancer. The extracellular matrix molecule tenascin-C promotes cancer by multiple mechanisms, yet the roles of tenascin-C in tumor immunity are incompletely understood. Using a 4NQO-induced oral squamous cell carcinoma (OSCC) model with abundant and absent tenascin-C, we demonstrated that tenascin-C enforced an immune-suppressive lymphoid stroma via CCL21/CCR7 signaling, leading to increased metastatic tumors. Through TLR4, tenascin-C increased expression of CCR7 in CD11c myeloid cells. By inducing CCL21 in lymphatic endothelial cells via integrin α9β1 and binding to CCL21, tenascin-C immobilized CD11c cells in the stroma. Inversion of the lymph node-to-tumor CCL21 gradient, recruitment of T regulatory cells, high expression of anti-inflammatory cytokines, and matrisomal components were hallmarks of the tenascin-C-instructed lymphoid stroma. Ablation of tenascin-C or CCR7 blockade inhibited the lymphoid immune-suppressive stromal properties, reducing tumor growth, progression, and metastasis. Thus, targeting CCR7 could be relevant in human head and neck tumors, as high tenascin-C expression and an immune-suppressive stroma correlate to poor patient survival.
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http://dx.doi.org/10.1158/2326-6066.CIR-20-0074DOI Listing
September 2020

A mouse model of MSU-induced acute inflammation suggests imiquimod-dependent targeting of as relevant therapy for gout patients.

Theranostics 2020 12;10(5):2158-2171. Epub 2020 Jan 12.

Université de Strasbourg, INSERM, ImmunoRhumatologie Moléculaire UMR_S 1109, Fédération de Médecine Translationnelle de Strasbourg, Faculté de Médecine, F-67000 Strasbourg, France.

: The role of Monosodium Urate (MSU) crystals in gout pathophysiology is well described, as is the major impact of IL-1β in the inflammatory reaction that constitutes the hallmark of the disease. However, despite the discovery of the NLRP3 inflammasome and its role as a Pattern Recognition Receptor linking the detection of a danger signal (MSU) to IL-1β secretion , the precise mechanisms leading to joint inflammation in gout patients are still poorly understood. : Acute urate crystal inflammation was obtained by subcutaneous injections of MSU crystals in mice. Symptoms were followed by scoring, cytokine quantification by ELISA and western blot, gene expression by RT-qPCR and RNAseq; Magnetic Resonance Imaging was also used to assess inflammation. : We provide an extensive clinical, biological and molecular characterization of an acute uratic inflammation mouse model which accurately mimics human gout. We report the efficacy of topical imiquimod treatment and its impact on Interferon-dependent down modulation of gene expression in this experimental model. : Our work reveals several key features of MSU-dependent inflammation and identifies novel therapeutic opportunities for gout patients.
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http://dx.doi.org/10.7150/thno.40650DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7019178PMC
April 2021

Matrix-Targeting Immunotherapy Controls Tumor Growth and Spread by Switching Macrophage Phenotype.

Cancer Immunol Res 2020 03 15;8(3):368-382. Epub 2020 Jan 15.

Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom.

The interplay between cancer cells and immune cells is a key determinant of tumor survival. Here, we uncovered how tumors exploit the immunomodulatory properties of the extracellular matrix to create a microenvironment that enables their escape from immune surveillance. Using orthotopic grafting of mammary tumor cells in immunocompetent mice and autochthonous models of breast cancer, we discovered how tenascin-C, a matrix molecule absent from most healthy adult tissues but expressed at high levels and associated with poor patient prognosis in many solid cancers, controls the immune status of the tumor microenvironment. We found that, although host-derived tenascin-C promoted immunity via recruitment of proinflammatory, antitumoral macrophages, tumor-derived tenascin-C subverted host defense by polarizing tumor-associated macrophages toward a pathogenic, immune-suppressive phenotype. Therapeutic monoclonal antibodies that blocked tenascin-C activation of Toll-like receptor 4 reversed this phenotypic switch and reduced tumor growth and lung metastasis , providing enhanced benefit in combination with anti-PD-L1 over either treatment alone. Combined tenascin-C:macrophage gene-expression signatures delineated a significant survival benefit in people with breast cancer. These data revealed a new approach to targeting tumor-specific macrophage polarization that may be effective in controlling the growth and spread of breast tumors.
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http://dx.doi.org/10.1158/2326-6066.CIR-19-0276DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7611136PMC
March 2020

Multi-omics dataset to decipher the complexity of drug resistance in diffuse large B-cell lymphoma.

Sci Rep 2019 01 29;9(1):895. Epub 2019 Jan 29.

Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC, Université de Strasbourg, CNRS UMR 7178, Strasbourg, France.

The prognosis of patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) remains unsatisfactory and, despite major advances in genomic studies, the biological mechanisms underlying chemoresistance are still poorly understood. We conducted for the first time a large-scale differential multi-omics investigation on DLBCL patient's samples in order to identify new biomarkers that could early identify patients at risk of R/R disease and to identify new targets that could determine chemorefractoriness. We compared a well-characterized cohort of R/R versus chemosensitive DLBCL patients by combining label-free quantitative proteomics and targeted RNA sequencing performed on the same tissues samples. The cross-section of both data levels allowed extracting a sub-list of 22 transcripts/proteins pairs whose expression levels significantly differed between the two groups of patients. In particular, we identified significant targets related to tumor metabolism (Hexokinase 3), microenvironment (IDO1, CXCL13), cancer cells proliferation, migration and invasion (S100 proteins) or BCR signaling pathway (CD79B). Overall, this study revealed several extremely promising biomarker candidates related to DLBCL chemorefractoriness and highlighted some new potential therapeutic drug targets. The complete datasets have been made publically available and should constitute a valuable resource for the future research.
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http://dx.doi.org/10.1038/s41598-018-37273-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6351558PMC
January 2019

ZMIZ1 Variants Cause a Syndromic Neurodevelopmental Disorder.

Am J Hum Genet 2019 02 10;104(2):319-330. Epub 2019 Jan 10.

Cook Children's Medical Center, Fort Worth, TX 76102, USA.

ZMIZ1 is a coactivator of several transcription factors, including p53, the androgen receptor, and NOTCH1. Here, we report 19 subjects with intellectual disability and developmental delay carrying variants in ZMIZ1. The associated features include growth failure, feeding difficulties, microcephaly, facial dysmorphism, and various other congenital malformations. Of these 19, 14 unrelated subjects carried de novo heterozygous single-nucleotide variants (SNVs) or single-base insertions/deletions, 3 siblings harbored a heterozygous single-base insertion, and 2 subjects had a balanced translocation disrupting ZMIZ1 or involving a regulatory region of ZMIZ1. In total, we identified 13 point mutations that affect key protein regions, including a SUMO acceptor site, a central disordered alanine-rich motif, a proline-rich domain, and a transactivation domain. All identified variants were absent from all available exome and genome databases. In vitro, ZMIZ1 showed impaired coactivation of the androgen receptor. In vivo, overexpression of ZMIZ1 mutant alleles in developing mouse brains using in utero electroporation resulted in abnormal pyramidal neuron morphology, polarization, and positioning, underscoring the importance of ZMIZ1 in neural development and supporting mutations in ZMIZ1 as the cause of a rare neurodevelopmental syndrome.
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http://dx.doi.org/10.1016/j.ajhg.2018.12.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6369415PMC
February 2019

An unusually high substitution rate in transplant-associated BK polyomavirus in vivo is further concentrated in HLA-C-bound viral peptides.

PLoS Pathog 2018 10 18;14(10):e1007368. Epub 2018 Oct 18.

Plateforme GENOMAX, Laboratoire d'ImmunoRhumatologie Moléculaire, INSERM UMR_S1109, LabEx Transplantex, Centre de Recherche d'Immunologie et d'Hématologie, Faculté de Médecine, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France.

Infection with human BK polyomavirus, a small double-stranded DNA virus, potentially results in severe complications in immunocompromised patients. Here, we describe the in vivo variability and evolution of the BK polyomavirus by deep sequencing. Our data reveal the highest genomic evolutionary rate described in double-stranded DNA viruses, i.e., 10(-3)-10(-5) substitutions per nucleotide site per year. High mutation rates in viruses allow their escape from immune surveillance and adaptation to new hosts. By combining mutational landscapes across viral genomes with in silico prediction of viral peptides, we demonstrate the presence of significantly more coding substitutions within predicted cognate HLA-C-bound viral peptides than outside. This finding suggests a role for HLA-C in antiviral immunity, perhaps through the action of killer cell immunoglobulin-like receptors. The present study provides a comprehensive view of viral evolution and immune escape in a DNA virus.
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http://dx.doi.org/10.1371/journal.ppat.1007368DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6207329PMC
October 2018

Multi-OMICS analyses unveil as a potential modifier gene in mevalonate kinase deficiency.

Ann Rheum Dis 2018 11 20;77(11):1675-1687. Epub 2018 Jul 20.

Laboratoire d'ImmunoRhumatologie Moléculaire, INSERM UMR_S1109, Plateforme GENOMAX, LabEx TRANSPLANTEX, Faculté de Médecine, Université de Strasbourg, Strasbourg, France.

Objectives: The objective of the present study was to explain why two siblings carrying both the same homozygous pathogenic mutation for the autoinflammatory disease hyper IgD syndrome, show opposite phenotypes, that is, the first being asymptomatic, the second presenting all classical characteristics of the disease.

Methods: Where single omics (mainly exome) analysis fails to identify culprit genes/mutations in human complex diseases, multiomics analyses may provide solutions, although this has been seldom used in a clinical setting. Here we combine exome, transcriptome and proteome analyses to decipher at a molecular level, the phenotypic differences between the two siblings.

Results: This multiomics approach led to the identification of a single gene-which harboured a rare missense variant and showed a significant overexpression of both mRNA and protein in the symptomatic versus the asymptomatic sister. This variant was shown to be of gain of function nature, involved in an increased activation of the Janus kinase/signal transducer and activator of transcription signalling (JAK/STAT) pathway, known to play a critical role in inflammatory diseases and for which specific biotherapies presently exist. Pathway analyses based on information from differentially expressed transcripts and proteins confirmed the central role of STAT1 in the proposed regulatory network leading to an increased inflammatory phenotype in the symptomatic sibling.

Conclusions: This study demonstrates the power of a multiomics approach to uncover potential clinically actionable targets for a personalised therapy. In more general terms, we provide a proteogenomics analysis pipeline that takes advantage of subject-specific genomic and transcriptomic information to improve protein identification and hence advance individualised medicine.
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http://dx.doi.org/10.1136/annrheumdis-2018-213524DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6225799PMC
November 2018

Hemodynamic Forces Tune the Arrest, Adhesion, and Extravasation of Circulating Tumor Cells.

Dev Cell 2018 04;45(1):33-52.e12

Université de Strasbourg, Strasbourg 67000, France; CNRS UMR7504, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Strasbourg 67000, France; LabEx NIE, Université de Strasbourg, Strasbourg 67000, France.

Metastatic seeding is driven by cell-intrinsic and environmental cues, yet the contribution of biomechanics is poorly known. We aim to elucidate the impact of blood flow on the arrest and the extravasation of circulating tumor cells (CTCs) in vivo. Using the zebrafish embryo, we show that arrest of CTCs occurs in vessels with favorable flow profiles where flow forces control the adhesion efficacy of CTCs to the endothelium. We biophysically identified the threshold values of flow and adhesion forces allowing successful arrest of CTCs. In addition, flow forces fine-tune tumor cell extravasation by impairing the remodeling properties of the endothelium. Importantly, we also observe endothelial remodeling at arrest sites of CTCs in mouse brain capillaries. Finally, we observed that human supratentorial brain metastases preferably develop in areas with low perfusion. These results demonstrate that hemodynamic profiles at metastatic sites regulate key steps of extravasation preceding metastatic outgrowth.
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http://dx.doi.org/10.1016/j.devcel.2018.02.015DOI Listing
April 2018

Mutations in signal recognition particle SRP54 cause syndromic neutropenia with Shwachman-Diamond-like features.

J Clin Invest 2017 Nov 3;127(11):4090-4103. Epub 2017 Oct 3.

Division of Pediatric Hematology, Hacettepe University Medical Faculty, Sihhiye, Ankara, Turkey.

Shwachman-Diamond syndrome (SDS) (OMIM #260400) is a rare inherited bone marrow failure syndrome (IBMFS) that is primarily characterized by neutropenia and exocrine pancreatic insufficiency. Seventy-five to ninety percent of patients have compound heterozygous loss-of-function mutations in the Shwachman-Bodian-Diamond syndrome (sbds) gene. Using trio whole-exome sequencing (WES) in an sbds-negative SDS family and candidate gene sequencing in additional SBDS-negative SDS cases or molecularly undiagnosed IBMFS cases, we identified 3 independent patients, each of whom carried a de novo missense variant in srp54 (encoding signal recognition particle 54 kDa). These 3 patients shared congenital neutropenia linked with various other SDS phenotypes. 3D protein modeling revealed that the 3 variants affect highly conserved amino acids within the GTPase domain of the protein that are critical for GTP and receptor binding. Indeed, we observed that the GTPase activity of the mutated proteins was impaired. The level of SRP54 mRNA in the bone marrow was 3.6-fold lower in patients with SRP54-mutations than in healthy controls. Profound reductions in neutrophil counts and chemotaxis as well as a diminished exocrine pancreas size in a SRP54-knockdown zebrafish model faithfully recapitulated the human phenotype. In conclusion, autosomal dominant mutations in SRP54, a key member of the cotranslation protein-targeting pathway, lead to syndromic neutropenia with a Shwachman-Diamond-like phenotype.
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http://dx.doi.org/10.1172/JCI92876DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5663364PMC
November 2017

HIV-Specific B Cell Frequency Correlates with Neutralization Breadth in Patients Naturally Controlling HIV-Infection.

EBioMedicine 2017 Jul 31;21:158-169. Epub 2017 May 31.

Sorbonne Universités, UPMC Univ Paris 06, INSERM U1135, CNRS ERL 8255, Center for Immunology and Microbial Infections - CIMI-Paris, Paris, France. Electronic address:

HIV-specific broadly neutralizing antibodies (bnAbs) have been isolated from patients with high viremia but also from HIV controllers that repress HIV-1 replication. In these elite controllers (ECs), multiple parameters contribute to viral suppression, including genetic factors and immune responses. Defining the immune correlates associated with the generation of bnAbs may help in designing efficient immunotherapies. In this study, in ECs either positive or negative for the HLA-B*57 protective allele, in treated HIV-infected and HIV-negative individuals, we characterized memory B cell compartments and HIV-specific memory B cells responses using flow cytometry and ELISPOT. ECs preserved their memory B cell compartments and in contrast to treated patients, maintained detectable HIV-specific memory B cell responses. All ECs presented IgG1+ HIV-specific memory B cells but some individuals also preserved IgG2+ or IgG3+ responses. Importantly, we also analyzed the capacity of sera from ECs to neutralize a panel of HIV strains including transmitted/founder virus. 29% and 21% of HLA-B*57+ and HLA-B*57- ECs, respectively, neutralized at least 40% of the viral strains tested. Remarkably, in HLA-B*57+ ECs the frequency of HIV-Env-specific memory B cells correlated positively with the neutralization breadth suggesting that preservation of HIV-specific memory B cells might contribute to the neutralizing responses in these patients.
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http://dx.doi.org/10.1016/j.ebiom.2017.05.029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5514383PMC
July 2017

Whole-Genome Sequencing of Seven Strains of Staphylococcus lugdunensis Allows Identification of Mobile Genetic Elements.

Genome Biol Evol 2017 05;9(5)

Université de Strasbourg, CHRU de Strasbourg, VBP EA7290, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Institut de bactériologie, Hôpitaux Universitaires de Strasbourg, France.

Coagulase negative staphylococci are normal inhabitant of the human skin flora that account for an increasing number of infections, particularly hospital-acquired infections. Staphylococcus lugdunensis has emerged as a most virulent species causing various infections with clinical characteristics close to what clinicians usually observe with Staphylococcus aureus and both bacteria share more than 70% of their genome. Virulence of S. aureus relies on a large repertoire of virulence factors, many of which are encoded on mobile genetic elements. S. lugdunensis also bears various putative virulence genes but only one complete genome with extensive analysis has been published with one prophage sequence (φSL2) and a unique plasmid was previously described. In this study, we performed de novo sequencing, whole genome assembly and annotation of seven strains of S. lugdunensis from VISLISI clinical trial. We searched for the presence of virulence genes and mobile genetics elements using bioinformatics tools. We identified four new prophages, named φSL2 to φSL4, belonging to the Siphoviridae class and five plasmids, named pVISLISI_1 to pVISLISI_5. Three plasmids are homologous to known plasmids that include, amongst others, one S. aureus plasmid. The two other plasmids were not described previously. This study provides a new context for the study of S. lugdunensis virulence suggesting the occurrence of several genetic recombination' with other staphylococci.
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http://dx.doi.org/10.1093/gbe/evx077DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5425232PMC
May 2017

A new MHC-linked susceptibility locus for primary Sjögren's syndrome: MICA.

Hum Mol Genet 2017 07;26(13):2565-2576

Plateforme GENOMAX, Laboratoire d'ImmunoRhumatologie Moléculaire, INSERM UMR_S1109, LabEx Transplantex, Centre de Recherche d'Immunologie et d'Hématologie. Faculté de Médecine, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, 67085 Strasbourg, France.

The association of primary Sjögren's syndrome (pSS) with Major Histocompatibility Complex (MHC) alleles is quintessential of MHC-disease associations. Indeed, although disease associations with classical HLA class I and II alleles/haplotypes are amply documented, further dissection is often prevented by the strong linkage disequilibrium across the entire MHC complex. Here we study the association of pSS, not with HLA genes, but with the non-conventional MHC encoded class I gene, MICA (MHC class I chain-related gene A). MICA is selectively expressed within epithelia, and is the major ligand for the activatory receptor, NKG2D, both attributes relevant to pSS' etiology. MICA-pSS association was studied in two independent (French and UK) cohorts representing a total of 959 cases and 1,043 controls. MICA*008 allele was shown to be significantly associated with pSS (pcor=2.61 × 10-35). A multivariate logistic regression showed that this association was independent of all major known MHC-linked risk loci/alleles, as well as other relevant candidate loci that are in linkage disequilibrium with MICA*008 i.e. HLA-B*08:01, rs3131619 (T), MICB*008, TNF308A, HLA-DRB1*03:01 and HLA-DRB1*15:01 (P = 1.84 × 10-04). Furthermore, independently of the MICA*008 allele, higher levels of soluble MICA proteins were detected in sera of pSS patients compared to healthy controls. This study hence defines MICA as a new, MHC-linked, yet HLA-independent, pSS risk locus and opens a new front in our understanding of the still enigmatic pathophysiology of this disease. The fact that the soluble MICA protein is further amplified in MICA*008 carrying individuals, might also be relevant in other auto-immune diseases and cancer.
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http://dx.doi.org/10.1093/hmg/ddx135DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6279161PMC
July 2017

Protein-altering MYH3 variants are associated with a spectrum of phenotypes extending to spondylocarpotarsal synostosis syndrome.

Eur J Hum Genet 2016 12 6;24(12):1746-1751. Epub 2016 Jul 6.

Plateforme GENOMAX, Laboratoire d'ImmunoRhumatologie Moléculaire, INSERM UMR_S1109, Centre de Recherche d'Immunologie et d'Hématologie, Faculté de Médecine, Fédération Hospitalo-Universitaire OMICARE, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France.

Spondylocarpotarsal synostosis syndrome (SCT) is a rare Mendelian disorder (OMIM #272460) characterized by prenatal vertebral fusion, scoliosis, short stature and carpal and tarsal synostosis. SCT is typically known as an autosomal recessive disease caused by variants in the FLNB gene. The genetic basis of the rarer cases of vertical transmissions remains unknown. In two independent families with symptoms related to autosomal dominant SCT, we identified - by exome sequencing - two protein-altering variants in the embryonic myosin heavy chain 3 (MYH3) gene. As MYH3 variants are also associated with distal arthrogryposis (DA1, DA2A, DA2B) and autosomal dominant multiple pterygium syndromes (MPS), the present study expands the phenotypic spectrum of MYH3 variants to autosomal dominant SCT. Vertebral, carpal and tarsal fusions observed in both families further confirm that MYH3 plays a key role in skeletal development.
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http://dx.doi.org/10.1038/ejhg.2016.84DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5117933PMC
December 2016

Reduced DICER1 Expression Bestows Rheumatoid Arthritis Synoviocytes Proinflammatory Properties and Resistance to Apoptotic Stimuli.

Arthritis Rheumatol 2016 08;68(8):1839-48

INSERM UMR-S1109, Fédération Hospitalo-Universitaire OMICARE, Centre de Recherche en Immunologie et Hématologie, and Université de Strasbourg, Strasbourg, France.

Objective: While the regulatory role of individual microRNAs (miRNAs) in rheumatoid arthritis (RA) is well established, the role of DICER1 in the pathogenesis of the disease has not yet been investigated. The purpose of this study was to analyze the expression of factors involved in miRNA biogenesis in fibroblast-like synoviocytes (FLS) from RA patients and to monitor the arthritis triggered by K/BxN serum transfer in mice deficient in the Dicer gene (Dicer(d/d) ).

Methods: The expression of genes and precursor miRNAs was quantified by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). MicroRNA macroarray profiling was monitored by qRT-PCR. Cytokines were quantified by enzyme-linked immunosorbent assay. Experimental arthritis in mice was achieved by the transfer of serum from K/BxN donors. Apoptosis was quantified using an enzyme-linked immunosorbent assay.

Results: We found decreased DICER1 and mature miRNA expression in synovial fibroblasts from RA patients. These cells were hyperresponsive to lipopolysaccharide, as evidenced by their increased interleukin-6 secretion upon stimulation. Experimental serum-transfer arthritis in Dicer(d/d) mice confirmed that an unbalanced biogenesis of miRNAs correlated with an enhanced inflammatory response. Synoviocytes from both RA patients and Dicer(d/d) mice exhibited increased resistance to apoptotic stimuli.

Conclusion: The findings of this study further substantiate the important role of DICER1 in the maintenance of homeostasis and the regulation of inflammatory responses.
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http://dx.doi.org/10.1002/art.39641DOI Listing
August 2016

Ubiquitin Receptor Protein UBASH3B Drives Aurora B Recruitment to Mitotic Microtubules.

Dev Cell 2016 Jan;36(1):63-78

Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Centre National de la Recherche Scientifique UMR 7104, Institut National de la Santé et de la Recherche Médicale U964, Université de Strasbourg, 67404 Illkirch, France. Electronic address:

Mitosis ensures equal segregation of the genome and is controlled by a variety of ubiquitylation signals on substrate proteins. However, it remains unexplored how the versatile ubiquitin code is read out during mitotic progression. Here, we identify the ubiquitin receptor protein UBASH3B as an important regulator of mitosis. UBASH3B interacts with ubiquitylated Aurora B, one of the main kinases regulating chromosome segregation, and controls its subcellular localization but not protein levels. UBASH3B is a limiting factor in this pathway and is sufficient to localize Aurora B to microtubules prior to anaphase. Importantly, targeting Aurora B to microtubules by UBASH3B is necessary for the timing and fidelity of chromosome segregation in human cells. Our findings uncover an important mechanism defining how ubiquitin attachment to a substrate protein is decoded during mitosis.
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http://dx.doi.org/10.1016/j.devcel.2015.12.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5400057PMC
January 2016

Circulating Human Eosinophils Share a Similar Transcriptional Profile in Asthma and Other Hypereosinophilic Disorders.

PLoS One 2015 2;10(11):e0141740. Epub 2015 Nov 2.

INSERM UMR S_1109, ImmunoRhumatologie Moléculaire, Labex Transplantex, Fédération de Médecine Translationnelle de Strasbourg, Université de Strasbourg, 67085, Strasbourg Cedex, France; Fédération Hospitalo-Universitaire, OMICARE, Centre de Recherche d'Immunologie et d'Hématologie, 67085, Strasbourg, France; Laboratoire Central d'Immunologie, Pôle de Biologie, Nouvel Hôpital Civil, Hôpitaux Universitaires de Strasbourg, 67091, Strasbourg Cedex, France.

Eosinophils are leukocytes that are released into the peripheral blood in a phenotypically mature state and are capable of being recruited into tissues in response to appropriate stimuli. Eosinophils, traditionally considered cytotoxic effector cells, are leukocytes recruited into the airways of asthma patients where they are believed to contribute to the development of many features of the disease. This perception, however, has been challenged by recent findings suggesting that eosinophils have also immunomodulatory functions and may be involved in tissue homeostasis and wound healing. Here we describe a transcriptome-based approach-in a limited number of patients and controls-to investigate the activation state of circulating human eosinophils isolated by flow cytometry. We provide an overview of the global expression pattern in eosinophils in various relevant conditions, e.g., eosinophilic asthma, hypereosinophilic dermatological diseases, parasitosis and pulmonary aspergillosis. Compared to healthy subjects, circulating eosinophils isolated from asthma patients differed in their gene expression profile which is marked by downregulation of transcripts involved in antigen presentation, pathogen recognition and mucosal innate immunity, whereas up-regulated genes were involved in response to non-specific stimulation, wounding and maintenance of homeostasis. Eosinophils from other hypereosinophilic disorders displayed a very similar transcriptional profile. Taken together, these observations seem to indicate that eosinophils exhibit non-specific immunomodulatory functions important for tissue repair and homeostasis and suggest new roles for these cells in asthma immunobiology.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0141740PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4629890PMC
June 2016

A de novo ADCY5 mutation causes early-onset autosomal dominant chorea and dystonia.

Mov Disord 2015 Mar 27;30(3):423-7. Epub 2014 Dec 27.

Plateforme GENOMAX, Laboratoire d'ImmunoRhumatologie Moléculaire, INSERM UMR_S1109, Centre de Recherche d'Immunologie et d'Hématologie, Faculté de Médecine, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France.

Importance: Apart from Huntington's disease, little is known of the genetics of autosomal dominant chorea associated with dystonia. Here we identify adenylate cyclase 5 (ADCY5) as a likely new causal gene for early-onset chorea and dystonia.

Observations: Whole exome sequencing in a three-generation family affected with autosomal dominant chorea associated with dystonia identified a single de novo mutation—c.2088+1G>A in a 5' donor splice-site of ADCY5—segregating with the disease. This mutation seeming leads to RNA instability and therefore ADCY5 haploinsufficiency.

Conclusions And Relevance: Our finding confirms the genetic/clinical heterogeneity of the disorder; corroborated by previous identification of ADCY5 mutations in one family with dyskinesia-facial myokymia and in two unrelated sporadic cases of paxoysmal choreic/dystonia-facial myokymia; ADCY5's high expression in the striatum and movement disorders in ADCY5-deficient mice. Hence ADCY5 genetic analyses may be relevant in the diagnostic workup of unexplained early-onset hyperkinetic movement disorders.
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http://dx.doi.org/10.1002/mds.26115DOI Listing
March 2015

A new mutation in the C-SH2 domain of PTPN11 causes Noonan syndrome with multiple giant cell lesions.

J Hum Genet 2014 Jan 14;59(1):57-9. Epub 2013 Nov 14.

Plateforme GENOMAX, Laboratoire d'ImmunoRhumatologie Moléculaire, INSERM UMR_S1109, Centre de Recherche d'Immunologie et d'Hématologie. Faculté de Médecine, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France.

Noonan syndrome (NS), an autosomal dominant multisystem disorder, is caused by the dysregulation of the RAS-MAPK pathway and is characterized by short stature, heart defects, pectus excavatum, webbed neck, learning problems, cryptorchidism and facial dysmorphism. We here present the clinical and molecular characterization of a family with NS and multiple giant cell lesions (MGCLs). The proband is a 12-year-old girl with NS and MGCL. Her mother shows typical NS without MGCL. Whole-exome sequencing of the girl, her mother and her healthy maternal grand parents revealed a previously unobserved mutation in exon 5 of the PTPN11 gene (c.598 A>T; p.N200Y), transmitted from the mother to the proband. As no other modification in the RAS-MAPK pathway genes as related to Rasopathies was detected in the proband, this report demonstrates for the first time that a unique mutation affecting this, otherwise unaffected signaling route, can cause both NS and NS/MGCL in the same family. This observation further confirms that NS/MGCL is not a distinct entity but rather that MGCL represents a rare complication of NS. Moreover, the localization of the p.N200Y mutation suggests an alternative molecular mechanism for the excessive phosphatase activity of the PTPN11-encoded protein.
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http://dx.doi.org/10.1038/jhg.2013.118DOI Listing
January 2014

Cullin 3 mediates SRC-3 ubiquitination and degradation to control the retinoic acid response.

Proc Natl Acad Sci U S A 2011 Dec 6;108(51):20603-8. Epub 2011 Dec 6.

Department of Functional Genomics and Cancer, Institut National de la Santé et de la Recherche Médicale U964, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7104, Université de Strasbourg, BP 10142, 67404 Illkirch Cedex, France.

SRC-3 is an important coactivator of nuclear receptors including the retinoic acid (RA) receptor α. Most of SRC-3 functions are facilitated by changes in the posttranslational code of the protein that involves mainly phosphorylation and ubiquitination. We recently reported that SRC-3 is degraded by the proteasome in response to RA. Here, by using an RNAi E3-ubiquitin ligase entry screen, we identified CUL-3 and RBX1 as components of the E3 ubiquitin ligase involved in the RA-induced ubiquitination and subsequent degradation of SRC-3. We also show that the RA-induced ubiquitination of SRC-3 depends on its prior phosphorylation at serine 860 that promotes binding of the CUL-3-based E3 ligase in the nucleus. Finally, phosphorylation, ubiquitination, and degradation of SRC-3 cooperate to control the dynamics of transcription. In all, this process participates to the antiproliferative effect of RA.
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http://dx.doi.org/10.1073/pnas.1102572108DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3251120PMC
December 2011

Expression proteomics of UPF1 knockdown in HeLa cells reveals autoregulation of hnRNP A2/B1 mediated by alternative splicing resulting in nonsense-mediated mRNA decay.

BMC Genomics 2010 Oct 14;11:565. Epub 2010 Oct 14.

Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK.

Background: In addition to acting as an RNA quality control pathway, nonsense-mediated mRNA decay (NMD) plays roles in regulating normal gene expression. In particular, the extent to which alternative splicing is coupled to NMD and the roles of NMD in regulating uORF containing transcripts have been a matter of debate.

Results: In order to achieve a greater understanding of NMD regulated gene expression we used 2D-DiGE proteomics technology to examine the changes in protein expression induced in HeLa cells by UPF1 knockdown. QPCR based validation of the corresponding mRNAs, in response to both UPF1 knockdown and cycloheximide treatment, identified 17 bona fide NMD targets. Most of these were associated with bioinformatically predicted NMD activating features, predominantly upstream open reading frames (uORFs). Strikingly, however, the majority of transcripts up-regulated by UPF1 knockdown were either insensitive to, or even down-regulated by, cycloheximide treatment. Furthermore, the mRNA abundance of several down-regulated proteins failed to change upon UPF1 knockdown, indicating that UPF1's role in regulating mRNA and protein abundance is more complex than previously appreciated. Among the bona fide NMD targets, we identified a highly conserved AS-NMD event within the 3' UTR of the HNRNPA2B1 gene. Overexpression of GFP tagged hnRNP A2 resulted in a decrease in endogenous hnRNP A2 and B1 mRNA with a concurrent increase in the NMD sensitive isoforms.

Conclusions: Despite the large number of changes in protein expression upon UPF1 knockdown, a relatively small fraction of them can be directly attributed to the action of NMD on the corresponding mRNA. From amongst these we have identified a conserved AS-NMD event within HNRNPA2B1 that appears to mediate autoregulation of HNRNPA2B1 expression levels.
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http://dx.doi.org/10.1186/1471-2164-11-565DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3091714PMC
October 2010

Computational analysis of full-length cDNAs reveals frequent coupling between transcriptional and splicing programs.

DNA Res 2008 Apr 14;15(2):63-72. Epub 2008 Feb 14.

Division of Bioinformatics, Biozentrum, University of Basel, Klingelbergstrasse 50-70, Basel CH-4056, Switzerland.

High-throughput sequencing studies revealed that the majority of human and mouse multi-exon genes have multiple splice forms. High-density oligonucleotide array-based measurements have further established that many exons are expressed in a tissue-specific manner. The mechanisms underlying the tissue-dependent expression of most alternative exons remain, however, to be understood. In this study, we focus on one possible mechanism, namely the coupling of (tissue specific) transcription regulation with alternative splicing. We analyzed the FANTOM3 and H-Invitational datasets of full-length mouse and human cDNAs, respectively, and found that in transcription units with multiple start sites, the inclusion of at least 15% and possibly up to 30% of the 'cassette' exons correlates with the use of specific transcription start sites (TSS). The vast majority of TSS-associated exons are conserved between human and mouse, yet the conservation is weaker when compared with TSS-independent exons. Additionally, the currently available data only support a weak correlation between the probabilities of TSS association of orthologous exons. Our analysis thus suggests frequent coupling of transcriptional and splicing programs, and provides a large dataset of exons on which the molecular basis of this coupling can be further studied.
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http://dx.doi.org/10.1093/dnares/dsm036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2650624PMC
April 2008

SPA: a probabilistic algorithm for spliced alignment.

PLoS Genet 2006 Apr 28;2(4):e24. Epub 2006 Apr 28.

Biozentrum, University of Basel, Basel, Switzerland.

Recent large-scale cDNA sequencing efforts show that elaborate patterns of splice variation are responsible for much of the proteome diversity in higher eukaryotes. To obtain an accurate account of the repertoire of splice variants, and to gain insight into the mechanisms of alternative splicing, it is essential that cDNAs are very accurately mapped to their respective genomes. Currently available algorithms for cDNA-to-genome alignment do not reach the necessary level of accuracy because they use ad hoc scoring models that cannot correctly trade off the likelihoods of various sequencing errors against the probabilities of different gene structures. Here we develop a Bayesian probabilistic approach to cDNA-to-genome alignment. Gene structures are assigned prior probabilities based on the lengths of their introns and exons, and based on the sequences at their splice boundaries. A likelihood model for sequencing errors takes into account the rates at which misincorporation, as well as insertions and deletions of different lengths, occurs during sequencing. The parameters of both the prior and likelihood model can be automatically estimated from a set of cDNAs, thus enabling our method to adapt itself to different organisms and experimental procedures. We implemented our method in a fast cDNA-to-genome alignment program, SPA, and applied it to the FANTOM3 dataset of over 100,000 full-length mouse cDNAs and a dataset of over 20,000 full-length human cDNAs. Comparison with the results of four other mapping programs shows that SPA produces alignments of significantly higher quality. In particular, the quality of the SPA alignments near splice boundaries and SPA's mapping of the 5' and 3' ends of the cDNAs are highly improved, allowing for more accurate identification of transcript starts and ends, and accurate identification of subtle splice variations. Finally, our splice boundary analysis on the human dataset suggests the existence of a novel non-canonical splice site that we also find in the mouse dataset. The SPA software package is available at http://www.biozentrum.unibas.ch/personal/nimwegen/cgi-bin/spa.cgi.
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http://dx.doi.org/10.1371/journal.pgen.0020024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1449883PMC
April 2006

Identification of clustered microRNAs using an ab initio prediction method.

BMC Bioinformatics 2005 Nov 7;6:267. Epub 2005 Nov 7.

Biozentrum, Universität Basel, Basel, Switzerland.

Background: MicroRNAs (miRNAs) are endogenous 21 to 23-nucleotide RNA molecules that regulate protein-coding gene expression in plants and animals via the RNA interference pathway. Hundreds of them have been identified in the last five years and very recent works indicate that their total number is still larger. Therefore miRNAs gene discovery remains an important aspect of understanding this new and still widely unknown regulation mechanism. Bioinformatics approaches have proved to be very useful toward this goal by guiding the experimental investigations.

Results: In this work we describe our computational method for miRNA prediction and the results of its application to the discovery of novel mammalian miRNAs. We focus on genomic regions around already known miRNAs, in order to exploit the property that miRNAs are occasionally found in clusters. Starting with the known human, mouse and rat miRNAs we analyze 20 kb of flanking genomic regions for the presence of putative precursor miRNAs (pre-miRNAs). Each genome is analyzed separately, allowing us to study the species-specific identity and genome organization of miRNA loci. We only use cross-species comparisons to make conservative estimates of the number of novel miRNAs. Our ab initio method predicts between fifty and hundred novel pre-miRNAs for each of the considered species. Around 30% of these already have experimental support in a large set of cloned mammalian small RNAs. The validation rate among predicted cases that are conserved in at least one other species is higher, about 60%, and many of them have not been detected by prediction methods that used cross-species comparisons. A large fraction of the experimentally confirmed predictions correspond to an imprinted locus residing on chromosome 14 in human, 12 in mouse and 6 in rat. Our computational tool can be accessed on the world-wide-web.

Conclusion: Our results show that the assumption that many miRNAs occur in clusters is fruitful for the discovery of novel miRNAs. Additionally we show that although the overall miRNA content in the observed clusters is very similar across the three considered species, the internal organization of the clusters changes in evolution.
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http://dx.doi.org/10.1186/1471-2105-6-267DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1315341PMC
November 2005
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