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[EN] Objectives Coeliac disease (CD) is a complex autoimmune disorder that develops in genetically susceptible individuals. Dietary gluten triggers an immune response for which the only available treatment so far is a strict, lifelong gluten free diet. Human leucocyte antigen (HLA) genes and several non-HLA regions have been associated with the genetic susceptibility to CD, but their role in the pathogenesis of the disease is still essentially unknown, making it complicated to develop much needed non-dietary treatments. Here, we describe the functional involvement of a CD-associated single-nudeotide polymorphism (SNP) located in the 5'UTR of XPO1 in the inflammatory environment characteristic of the coeliac intestinal epithelium. Design The function of the CD-associated SNP was investigated using an intestinal cell line heterozygous for the SNP, N6-methyladenosine (m(6)A)-related knock-out and HLA-DQ2 mice, and human samples from patients with CD. Results Individuals harbouring the risk allele had higher m(6)A methylation in the 5'UTR of XPO1 RNA, rendering greater XPO1 protein amounts that led to downstream nuclear factor kappa B (NFkB) activity and subsequent inflammation. Furthermore, gluten exposure increased overall m(6)A methylation in humans as well as in in vitro and in vivo models. Conclusion We identify a novel m(6)A-XPO1-NFkB pathway that is activated in CD patients. The findings will prompt the development of new therapeutic approaches directed at m(6)A proteins and XPO1, a target under evaluation for the treatment of intestinal disorders. This study was supported by a grant from the Spanish Ministry of Science, Universities and Innovation (PGC2018-097573-A-I00) to AC-R. JRB was funded by ISCIII Research project PI16/00258, cofinanced by the Spanish Ministry of Economy and Competitiveness and by the European Union ERDF/ESF 'A way to make Europe'. AO-G and MS-D were funded by predoctoral fellowships from the Basque Government and the University of the Basque Country respectively. DS and LH were funded by the Spanish Ministry (MINECO) (SAF2017-83813-C3-1-R) and cofunded by the ERDF, the Centro de Investigacion Biomedica en Red de Fisiopatologia de la Obesidad y la Nutricion (CIBEROBN) (Grant CB06/03/0001 to DS), the Government of Catalonia (2017SGR278 to DS), and the Fundacio La Marato de TV3 (201627-30 to DS). CH is a Howard Hughes Medical Institute Investigator and has been funded by the National Institute of Health HG008935. We would like to thank Xuechen Yu and Justin Vargas for processing the adult CD biopsy samples obtained from Columbia University. EFV is supported by a CIHR grant 168840 and holds a Canada Research Chair.

Technological advances in high-throughput sequencing in combination with antibody enrichment and/or induced nucleotide-specific chemical modifications have accelerated the mapping of epitranscriptomic modifications. However, site-specific detection and quantification of m6A are still technically challenging. Here, we describe a simple RT-QPCR-based approach for the relative quantification of candidate m6A regions that takes advantage of the diminished capacity of BstI enzyme to retrotranscribe m6A residues.

mRNA stability influences gene expression and translation in almost all living organisms, and the levels of mRNA molecules in the cell are determined by a balance between production and decay. Maintaining an accurate balance is crucial for the correct function of a wide variety of biological processes and to maintain an appropriate cellular homeostasis. Long non-coding RNAs (lncRNAs) have been shown to participate in the regulation of gene expression through different molecular mechanisms, including mRNA stabilization. In this review we provide an overview on the molecular mechanisms by which lncRNAs modulate mRNA stability and decay. We focus on how lncRNAs interact with RNA binding proteins and microRNAs to avoid mRNA degradation, and also on how lncRNAs modulate epitranscriptomic marks that directly impact on mRNA stability. LncRNA work in author’s laboratory is supported by European Foundation for the Study of Diabetes (EFSD)-EFSD/JDRF/Lilly Programme on Type 1 Diabetes Research and the Spanish Ministry of Science, Innovation and Universities (PID2019-104475GA-I00) to I.S; and Spanish Ministry of Science, Innovation and Universities (SAF2017-91873-EXP and PGC2018-097573-A-I00) to ACR. M.S.D. and I.G.M. are supported by a Predoctoral Fellowship Grant from the UPV/EHU (Universidad del País Vasco/Euskal Herriko Unibertsitatea) and A.O.G. is supported by a Predoctoral Fellowship Grant from the Education Department of Basque Government.

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract that develops due to the interaction between genetic and environmental factors. More than 160 loci have been associated with IBD, but the functional implication of many of the associated genes remains unclear. N6-Methyladenosine (m6A) is the most abundant internal modification in mRNA. m6A methylation regulates many aspects of mRNA metabolism, playing important roles in the development of several pathologies. Interestingly, SNPs located near or within m6A motifs have been proposed as possible contributors to disease pathogenesis. We hypothesized that certain IBD-associated SNPs could regulate the function of genes involved in IBD development via m6A-dependent mechanisms. We used online available GWAS, m6A and transcriptome data to find differentially expressed genes that harbored m6A-SNPs associated with IBD. Our analysis resulted in five candidate genes corresponding to two of the major IBD subtypes: UBE2L3 and SLC22A4 for Crohn&rsquo, s Disease and TCF19, C6orf47 and SNAPC4 for Ulcerative Colitis. Further analysis using in silico predictions and co-expression analyses in combination with in vitro functional studies showed that our candidate genes seem to be regulated by m6A-dependent mechanisms. These findings provide the first indication of the implication of RNA methylation events in IBD pathogenesis.

Medulloblastoma is the most common and malignant pediatric brain tumor in childhood. It originates from dysregulation of cerebellar development, due to an excessive proliferation of cerebellar granule neuron precursor cells (CGNPs). The underlying molecular mechanisms, except for the role of SHH and WNT pathways, remain largely unknown. ERBB4 is a tyrosine kinase receptor whose activity in cancer is tissue dependent. In this study, we characterized the role of ERBB4 during cerebellum development and medulloblastoma progression paying particular interests to its role in CGNPs and medulloblastoma stem cells (MBSCs). Our results show that ERBB4 is expressed in the CGNPs during cerebellum development where it plays a critical role in migration, apoptosis and differentiation. Similarly, it is enriched in the population of MBSCs, where also controls those critical processes, as well as self-renewal and tumor initiation for medulloblastoma progression. These results are translated to clinical samples where high levels of ERBB4 correlate with poor outcome in Group 4 and all medulloblastomas groups. Transcriptomic analysis identified critical processes and pathways altered in cells with knock-down of ERBB4. These results highlight the impact and underlying mechanisms of ERBB4 in critical processes during cerebellum development and medulloblastoma.