A regulatory network comprising let-7 miRNA and SMUG1 is associated with good prognosis in ER+ breast tumours

Single-strand selective uracil–DNA glycosylase 1 (SMUG1) initiates base excision repair (BER) of uracil and oxidized pyrimidines. SMUG1 status has been associated with cancer risk and therapeutic response in breast carcinomas and other cancer types. However, SMUG1 is a multifunctional protein involved, not only, in BER but also in RNA quality control, and its function in cancer cells is unclear. Here we identify several novel SMUG1 interaction partners that functions in many biological processes relevant for cancer development and treatment response. Based on this, we hypothesized that the dominating function of SMUG1 in cancer might be ascribed to functions other than BER. We define a bad prognosis signature for SMUG1 by mapping out the SMUG1 interaction network and found that high expression of genes in the bad prognosis network correlated with lower survival probability in ER(+) breast cancer. Interestingly, we identified hsa-let-7b-5p microRNA as an upstream regulator of the SMUG1 interactome. Expression of SMUG1 and hsa-let-7b-5p were negatively correlated in breast cancer and we found an inhibitory auto-regulatory loop between SMUG1 and hsa-let-7b-5p in the MCF7 breast cancer cells. We conclude that SMUG1 functions in a gene regulatory network that influence the survival and treatment response in several cancers

Etude de la fonction de la protéine humaine TAF15 dans la régulation de l'expression génique

TAF15 (TBP-associated factor 15) constitue avec EWS (Ewing sarcoma) et TLS (translocated in liposarcoma) la famille des protéines TET, dont les gènes correspondants sont fréquemment transloqués dans les sarcomes humains. TAF15 fait partie d une sous-population du facteur général de transcription TFIID et de l ARN polymérase II. Une analyse sur puce à ADN a révélé que 7.5% des gènes présents sur la puce sont dérégulés en absence de TAF15. Une analyse plus détaillée de certains gènes régulés par TAF15 a montré que TAF15 agit au niveau transcriptionnel et est recruté sur les transcrits de ses gènes cibles. En outre, TAF15 forme un nouveau complexe avec le petit ARN nucléaire U1 (U1 snRNA), qui est distinct de la particule ribonucléoprotéique U1 bien caractérisée dans l épissage. Puisque TAF15 lie à la fois l ARN U1 et ses transcrits cibles et contrôle aussi la transcription d un groupe de gènes, TAF15 peut participer au couplage de la transcription et de l épissage de certains gènes.TAF15 (TBP-associated factor 15) forms with EWS (Ewing sarcoma) and TLS (translocated in liposarcoma) the TET protein family, whose genes are frequently translocated in human sarcomas. TAF15 has been identified on the basis of its association with a subpopulation of the general transcription factor TFIID and RNA polymerase II. We found by gene expression profiling that about 7.5% of the genes were misregulated upon TAF15 knockdown. A detailed analysis of certain TAF15-regulated genes showed that TAF15 acts at the transcriptional level and is recruited on the transcripts of its target genes. Most importantly, TAF15 can form a novel complex with the spliceosomal small nuclear U1 RNA (U1 snRNA) that is distinct from the well-characterized small nuclear ribonucleoprotein U1 particle. Since TAF15 binds both the U1 snRNA and its target transcripts and also controls transcription of a specific set of genes, TAF15 may participate in the coupling of transcription and splicing on certain genes.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

PRMT1 mediated methylation of TAF15 is required for its positive gene regulatory function.

International audienceTAF15 (formerly TAF(II)68) is a nuclear RNA-binding protein that is associated with a distinct population of TFIID and RNA polymerase II complexes. TAF15 harbours an N-terminal activation domain, an RNA recognition motif (RRM) and many Arg-Gly-Gly (RGG) repeats at its C-terminal end. The N-terminus of TAF15 serves as an essential transforming domain in the fusion oncoprotein created by chromosomal translocation in certain human chondrosarcomas. Post-transcriptional modifications (PTMs) of proteins are known to regulate their activity, however, nothing is known on how PTMs affect TAF15 function. Here we demonstrate that endogenous human TAF15 is methylated in vivo at its numerous RGG repeats. Furthermore, we identify protein arginine N-methyltransferase 1 (PRMT1) as a TAF15 interactor and the major PRMT responsible for its methylation. In addition, the RGG repeat-containing C-terminus of TAF15 is responsible for the shuttling between the nucleus and the cytoplasm and the methylation of RGG repeats affects the subcellular localization of TAF15. The methylation of TAF15 by PRMT1 is required for the ability of TAF15 to positively regulate the expression of the studied endogenous TAF15-target genes. Our findings demonstrate that arginine methylation of TAF15 by PRMT1 is a crucial event determining its proper localization and gene regulatory function

Human U1 snRNA forms a new chromatin-associated snRNP with TAF15.

International audienceThe U1 small nuclear RNA (snRNA)--in the form of the U1 spliceosomal Sm small nuclear ribonucleoprotein particle (snRNP) that contains seven Sm and three U1-specific RNP proteins-has a crucial function in the recognition and removal of pre-messenger RNA introns. Here, we show that a fraction of human U1 snRNA specifically associates with the nuclear RNA-binding protein TBP-associated factor 15 (TAF15). We show that none of the known protein components of the spliceosomal U1-Sm snRNP interacts with the newly identified U1-TAF15 snRNP. In addition, the U1-TAF15 snRNP tightly associates with chromatin in an RNA-dependent manner and accumulates in nucleolar caps upon transcriptional inhibition. The Sm-binding motif of U1 snRNA is essential for the biogenesis of both U1-Sm and U1-TAF15 snRNPs, suggesting that the U1-TAF15 particle is produced by remodelling of the U1-Sm snRNP. A demonstration that human U1 snRNA forms at least two structurally distinct snRNPs supports the idea that the U1 snRNA has many nuclear functions

SMUG1 Promotes Telomere Maintenance through Telomerase RNA Processing

Telomerase biogenesis is a complex process where several steps remain poorly understood. Single-strand-selective uracil-DNA glycosylase (SMUG1) associates with the DKC1-containing H/ACA ribonucleoprotein complex, which is essential for telomerase biogenesis. Herein, we show that SMUG1 interacts with the telomeric RNA component (hTERC) and is required for co-transcriptional processing of the nascent transcript into mature hTERC. We demonstrate that SMUG1 regulates the presence of base modifications in hTERC, in a region between the CR4/CR5 domain and the H box. Increased levels of hTERC base modifications are accompanied by reduced DKC1 binding. Loss of SMUG1 leads to an imbalance between mature hTERC and its processing intermediates, leading to the accumulation of 3′-polyadenylated and 3′-extended intermediates that are degraded in an EXOSC10-independent RNA degradation pathway. Consequently, SMUG1-deprived cells exhibit telomerase deficiency, leading to impaired bone marrow proliferation in Smug1-knockout mice

SMUG1 Promotes Telomere Maintenance through Telomerase RNA Processing

Telomerase biogenesis is a complex process where several steps remain poorly understood. Single-strand-selective uracil-DNA glycosylase (SMUG1) associates with the DKC1-containing H/ACA ribonucleoprotein complex, which is essential for telomerase biogenesis. Herein, we show that SMUG1 interacts with the telomeric RNA component (hTERC) and is required for co-transcriptional processing of the nascent transcript into mature hTERC. We demonstrate that SMUG1 regulates the presence of base modifications in hTERC, in a region between the CR4/CR5 domain and the H box. Increased levels of hTERC base modifications are accompanied by reduced DKC1 binding. Loss of SMUG1 leads to an imbalance between mature hTERC and its processing intermediates, leading to the accumulation of 3′-polyadenylated and 3′-extended intermediates that are degraded in an EXOSC10-independent RNA degradation pathway. Consequently, SMUG1-deprived cells exhibit telomerase deficiency, leading to impaired bone marrow proliferation in Smug1-knockout mice

Vaccination coverage of children with inflammatory bowel disease after an awareness campaign on the risk of infection

International audienceBACKGROUND: Children with inflammatory bowel disease are at risk of vaccine-preventable diseases mostly due to immunosuppressive drugs. AIM: To evaluate coverage after an awareness campaign informing patients, their parents and general practitioner about the vaccination schedule. METHODS: Vaccination coverage was firstly evaluated and followed by an awareness campaign on the risk of infection via postal mail. The trial is a case-control study on the same patients before and after the awareness campaign. Overall, 92 children were included. A questionnaire was then completed during a routine appointment to collect data including age at diagnosis, age at data collection, treatment history, and vaccination status. RESULTS: Vaccination rates significantly increased for vaccines against diphtheria-tetanus-poliomyelitis (92% vs. 100%), Haemophilus influenzae (88% vs. 98%), hepatitis B (52% vs. 71%), pneumococcus (36% vs. 57%), and meningococcus C (17% vs. 41%) (p\textless0.05). Children who were older at diagnosis were 1.26 times more likely to be up-to-date with a minimum vaccination schedule (diphtheria-tetanus-poliomyelitis, pertussis, H. influenzae, measles-mumps-rubella, tuberculosis) (p=0.002). CONCLUSION: Informing inflammatory bowel disease patients, their parents and general practitioner about the vaccination schedule via postal mail is easy, inexpensive, reproducible, and increases vaccination coverage. This method reinforces information on the risk of infection during routine visit

Uracil Accumulation and Mutagenesis Dominated by Cytosine Deamination in CpG Dinucleotides in Mice Lacking UNG and SMUG

Both a DNA lesion and an intermediate for antibody maturation, uracil is primarily processed by base excision repair (BER), either initiated by uracil-DNA glycosylase (UNG) or by single-strand selective monofunctional uracil DNA glycosylase (SMUG1). The relative in vivo contributions of each glycosylase remain elusive. To assess the impact of SMUG1 deficiency, we measured uracil and 5-hydroxymethyluracil, another SMUG1 substrate, in Smug1−/− mice. We found that 5-hydroxymethyluracil accumulated in Smug1−/− tissues and correlated with 5-hydroxymethylcytosine levels. The highest increase was found in brain, which contained about 26-fold higher genomic 5-hydroxymethyluracil levels than the wild type. Smug1−/− mice did not accumulate uracil in their genome and Ung−/− mice showed slightly elevated uracil levels. Contrastingly, Ung−/−Smug1−/− mice showed a synergistic increase in uracil levels with up to 25-fold higher uracil levels than wild type. Whole genome sequencing of UNG/SMUG1-deficient tumours revealed that combined UNG and SMUG1 deficiency leads to the accumulation of mutations, primarily C to T transitions within CpG sequences. This unexpected sequence bias suggests that CpG dinucleotides are intrinsically more mutation prone. In conclusion, we showed that SMUG1 efficiently prevent genomic uracil accumulation, even in the presence of UNG, and identified mutational signatures associated with combined UNG and SMUG1 deficiency