Project description:The function and retention/reprogramming of epigenetic marks during the germline-to-embryo transition is a key issue in developmental and cellular biology, with relevance to stem cell programming and trans-generational inheritance. In zebrafish, DNAme patterns are programmed in transcriptionally-quiescent early cleavage embryos; paternally-inherited patterns are maintained, whereas maternal patterns are reprogrammed to match the paternal pattern. Here we show that a ‘placeholder’ nucleosome, containing the histone H2A variant H2A.Z(FV) and H3K4me1, occupies virtually all regions lacking DNAme in both sperm and cleavage embryos – residing at promoters encoding housekeeping and early embryonic transcription factors. Upon genome-wide transcriptional onset, genes with the Placeholder become either active H3K4me3-marked or silent H3K4me3/K27me3-marked (bivalent). Importantly, functional perturbation causing Placeholder loss confers DNAme acquisition, whereas acquisition/expansion of Placeholder confers DNA hypomethylation and improper gene activation. Thus, during transcriptionally quiescent stages (gamete-zygote-cleavage), an H2A.Z(FV)/H3K4me1-containing Placeholder nucleosome deters DNAme, poising parental genes for either gene-specific activation or facultative repression.
Project description:The function and retention/reprogramming of epigenetic marks during the germline-to-embryo transition is a key issue in developmental and cellular biology, with relevance to stem cell programming and trans-generational inheritance. In zebrafish, DNAme patterns are programmed in transcriptionally-quiescent early cleavage embryos; paternally-inherited patterns are maintained, whereas maternal patterns are reprogrammed to match the paternal pattern. Here we show that a ‘placeholder’ nucleosome, containing the histone H2A variant H2A.Z(FV) and H3K4me1, occupies virtually all regions lacking DNAme in both sperm and cleavage embryos – residing at promoters encoding housekeeping and early embryonic transcription factors. Upon genome-wide transcriptional onset, genes with the Placeholder become either active H3K4me3-marked or silent H3K4me3/K27me3-marked (bivalent). Importantly, functional perturbation causing Placeholder loss confers DNAme acquisition, whereas acquisition/expansion of Placeholder confers DNA hypomethylation and improper gene activation. Thus, during transcriptionally quiescent stages (gamete-zygote-cleavage), an H2A.Z(FV)/H3K4me1-containing Placeholder nucleosome deters DNAme, poising parental genes for either gene-specific activation or facultative repression.
Project description:The function and retention/reprogramming of epigenetic marks during the germline-to-embryo transition is a key issue in developmental and cellular biology, with relevance to stem cell programming and trans-generational inheritance. In zebrafish, DNAme patterns are programmed in transcriptionally-quiescent early cleavage embryos; paternally-inherited patterns are maintained, whereas maternal patterns are reprogrammed to match the paternal pattern. Here we show that a ‘placeholder’ nucleosome, containing the histone H2A variant H2A.Z(FV) and H3K4me1, occupies virtually all regions lacking DNAme in both sperm and cleavage embryos – residing at promoters encoding housekeeping and early embryonic transcription factors. Upon genome-wide transcriptional onset, genes with the Placeholder become either active H3K4me3-marked or silent H3K4me3/K27me3-marked (bivalent). Importantly, functional perturbation causing Placeholder loss confers DNAme acquisition, whereas acquisition/expansion of Placeholder confers DNA hypomethylation and improper gene activation. Thus, during transcriptionally quiescent stages (gamete-zygote-cleavage), an H2A.Z(FV)/H3K4me1-containing Placeholder nucleosome deters DNAme, poising parental genes for either gene-specific activation or facultative repression.
Project description:Hepatitis C virus (HCV) and human immunodeficiency virus (HIV) hijack the host exosomal machinery as an additional mechanism of infection and evasion of the immune system, modifying the small RNA (smRNA) cargo during infection. We characterized the surface epitopes of extracellular vesicles (EVs) from plasma HIV/HCV-coinfected patients and their smRNA cargo profile, by comparing different isolation procedures. Six EVs isolation procedures were compared: ultracentrifugation, and five different polyethylene glycol-based methods (commercial, combined with a column purification step and two custom); and two RNA commercial kits (phenol and non-phenol based) were used. High-throughput sequencing of smRNAs was performed. Exosomal surface epitopes were analyzed by the MACSPlex Exosome Kit. Four miRNAs displayed differences among protocols (hsa-miR-205-5p and hsa-let-7a/b/f-5p). The selection of RNA isolation kit impacted on the detection of miRNAs and other smRNAs, where the phenol-based RNA isolation kit performed acceptably. EVs surface was enriched with HLA-DR/DP/DQ, CD81, and CD8. There were three liver-specific miRNAs overexpressed (let-7a-5p, miR-21-5p and hsa-miR-122-5p), thus, EVs cargo might reflect liver disease evolution. Other smRNAs such as piwi-interacting RNAs were also detected for the first time. Custom polyethylene glycol precipitation-based methods combined with an RNA phenol-based kit yielded the higher number of smRNAs for EVs isolated from plasma HIV/HCV patients.
Project description:ObjectivesTo evaluate the diagnostic performance of seven non-invasive tests (NITs) of liver fibrosis and to assess fibrosis progression over time in HIV/HCV co-infected patients.MethodsTransient elastography (TE) and six blood tests were compared to histopathological fibrosis stage (METAVIR). Participants were followed over three years with NITs at yearly intervals.ResultsArea under the receiver operating characteristic curve (AUROC) for significant fibrosis (> = F2) in 105 participants was highest for TE (0.85), followed by FIB-4 (0.77), ELF-Test (0.77), APRI (0.76), Fibrotest (0.75), hyaluronic acid (0.70), and Hepascore (0.68). AUROC for cirrhosis (F4) was 0.97 for TE followed by FIB-4 (0.91), APRI (0.89), Fibrotest (0.84), Hepascore (0.82), ELF-Test (0.82), and hyaluronic acid (0.79). A three year follow-up was completed by 87 participants, all on antiretroviral therapy and in 20 patients who completed HCV treatment (9 with sustained virologic response). TE, APRI and Fibrotest did not significantly change during follow-up. There was weak evidence for an increase of FIB-4 (mean increase: 0.22, p = 0.07). 42 participants had a second liver biopsy: Among 38 participants with F0-F3 at baseline, 10 were progessors (1-stage increase in fibrosis, 8 participants; 2-stage, 1; 3-stage, 1). Among progressors, mean increase in TE was 3.35 kPa, in APRI 0.36, and in FIB-4 0.75. Fibrotest results did not change over 3 years.ConclusionTE was the best NIT for liver fibrosis staging in HIV/HCV co-infected patients. APRI-Score, FIB-4 Index, Fibrotest, and ELF-Test were less reliable. Routinely available APRI and FIB-4 performed as good as more expensive tests. NITs did not change significantly during a follow-up of three years, suggesting slow liver disease progression in a majority of HIV/HCV co-infected persons on antiretroviral therapy.
Project description:Background & aims: MicroRNAs (miRNAs) encapsulated in EVs are potential diagnostic and prognostic biomarkers. However, discrepancies on miRNA patterns and their validation are still frequent due to differences in sample origin, EVs isolation, miRNA extraction and sequencing methods. Selecting appropriate EVs isolation methods is therefore a critical step for miRNA-based biomarker discovery. The aim of the present study is to find the most suitable EVs isolation method for miRNAs sequencing adequate for clinical application. Material & Methods EVs were isolated by Size Exclusion Chromatography (SEC), iodixanol gradients (GRAD) and the combination of both (SEC+GRAD), using the same plasma sample, in triplicate isolation assays. Isolated EVs were characterized and RNA was extracted. Three different protocols for miRNA library preparation were compared (NEBNext, NEXTFlex and SMARTer smRNA-seq) and miRNAs encapsulated on EVs were sequenced using NextSeq 500 system (Illumina). Finally, the yield, abundance and diversity of miRNAs using the three different EVs isolation protocols were analyzed and compared between them. Results The majority of lipoproteins, total cholesterol and plasma proteins were removed from the EVs-containing fractions by using SEC, GRAD, and SEC+GRAD. SEC method recovered a larger amount of EVs followed by GRAD and SEC+GRAD, while GRAD and SEC+GRAD yielded the purest vesicles. NEBNext was the library preparation kit that showed the highest reproducibility among replicas, higher number of reads corresponding to miRNAs and more different miRNAs, followed by NEXTFlex and SMARTer smRNA-seq. GRAD method showed the highest reproducibility among replicas, a higher number of reads corresponding to miRNAs and more different miRNAs, followed by SEC and SEC+GRAD methods. Conclusions These results render the GRAD method to isolate EVs as one of the most appropriate to detect miRNAs from Evs.