Uniparental silencing of 35S rRNA genes (rDNA), known as nucleolar dominance (ND), is common in interspecific hybrids. Allotetraploid Tragopogon mirus composed of Tragopogon dubius (d) and Tragopogon porrifolius (p) genomes shows highly variable ND. To examine the molecular basis of such variation, we studied the genetic and epigenetic features of rDNA homeologs in several lines derived from recently and independently formed natural populations. Inbred lines derived from T. mirus with a dominant d-rDNA homeolog transmitted this expression pattern over generations, which may explain why it is prevalent among natural populations. In contrast, lines derived from the p-rDNA dominant progenitor were meiotically unstable, frequently switching to co-dominance. Interpopulation crosses between progenitors displaying reciprocal ND resulted in d-rDNA dominance, indicating immediate suppression of p-homeologs in F1 hybrids. Original p-rDNA dominance was not restored in later generations, even in those segregants that inherited the corresponding parental rDNA genotype, thus indicating the generation of additional p-rDNA and d-rDNA epigenetic variants. Despite preserved intergenic spacer (IGS) structure, they showed altered cytosine methylation and chromatin condensation patterns, and a correlation between expression, hypomethylation of RNA Pol I promoters and chromatin decondensation was apparent. Reversion of such epigenetic variants occurred rarely, resulting in co-dominance maintained in individuals with distinct genotypes. Generally, interpopulation crosses may generate epialleles that are not present in natural populations, underlying epigenetic dynamics in young allopolyploids. We hypothesize that highly expressed variants with distinct IGS features may induce heritable epigenetic reprogramming of the partner rDNA arrays, harmonizing the expression of thousands of genes in allopolyploids.

• MeSH
• DNA rostlinná genetika   MeSH
• epigenomika * MeSH
• fenotyp MeSH
• genom rostlinný genetika   MeSH
• genotyp MeSH
• hybridizace genetická MeSH
• metylace DNA MeSH
• molekulární evoluce * MeSH
• polyploidie MeSH
• regulace genové exprese u rostlin * MeSH
• ribozomální DNA genetika   MeSH
• Tragopogon genetika   MeSH
• umlčování genů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Hepatocyte nuclear factor 1-beta (HNF-1-beta) is a transcription factor involved in cancerogenesis of various tumors, including endometrioid carcinoma. We performed comprehensive analysis of HNF-1-beta in lesions of the endometrium, including protein expression and genetic and epigenetic changes. Expression of HNF-1-beta was analyzed immunohistochemically in 320 cases including both tumor and non-tumor endometrial lesions. Promoter methylation and genetic variants were evaluated, using bisulphite and direct sequencing, in 30 (18 fresh frozen, 12 FFPE tumors) endometrioid carcinomas (ECs) and 15 ovarian clear cell carcinomas (OCCCs) as a control group. We detected expression of HNF-1-beta in 28 % of ECs (51/180 cases), 26 % of serous carcinoma (7/27 cases), 83 % of endometrial clear cell carcinoma (15/18 cases), 93 % of hyperplastic polyps with atypias (13/14 cases), 100 % of hyperplastic polyps without atypias (16/16 cases), 88 % of hyperplasias with atypias (14/16 cases), 91 % of hyperplasias without atypias (10/11 cases), and in ≥80 % of different normal endometrium samples. The control group of OCCCs showed HNF-1-beta expression in 95 % (18/19 cases). Methylation in promoter region was detected in 13.3 % (4/30) of ECs, but not in corresponding normal tissue where available, nor in OCCCs (0/15 cases). Mutation analysis revealed truncating variant c.454C > T (p.Gln152X) in one EC and missense variant c.848C > T (p.Ala283Val) was detected in one OCCC. In conclusion, expression of HNF-1-beta was detected in various extents in all types of lesions analyzed, nevertheless its strong expression was mostly limited to clear cell carcinomas. Biological significance of genetic and epigenetic changes needs further investigation.

• MeSH
• adenokarcinom z jasných buněk genetika   patologie   MeSH
• endometroidní karcinom genetika   patologie   MeSH
• epigeneze genetická genetika   MeSH
• epigenomika metody   MeSH
• genetická variace genetika   MeSH
• hepatocytární jaderný faktor 1-beta genetika   MeSH
• imunohistochemie metody   MeSH
• lidé MeSH
• metylace DNA genetika   MeSH
• nádorové biomarkery genetika   MeSH
• nádory endometria genetika   patologie   MeSH
• promotorové oblasti (genetika) genetika   MeSH
• serózní cystadenokarcinom genetika   patologie   MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Epigenetic DNA modifications are pivotal in eukaryotic gene expression, but their regulatory significance in bacteria is less understood. In Synechocystis 6803, the DNA methyltransferase M.Ssp6803II modifies the first cytosine in the GGCC motif, forming N4-methylcytosine (GGm4CC). Deletion of the sll0729 gene encoding M.Ssp6803II (∆sll0729) caused a bluish phenotype due to reduced chlorophyll levels, which was reversed by suppressor mutations. Re-sequencing of 7 suppressor clones revealed a common GGCC to GGTC mutation in the slr1790 promoter's discriminator sequence, encoding protoporphyrinogen IX oxidase, HemJ, crucial for tetrapyrrole biosynthesis. Transcriptomic and qPCR analyses indicated aberrant slr1790 expression in ∆sll0729 mutants. This aberration led to the accumulation of coproporphyrin III and protoporphyrin IX, indicative of impaired HemJ activity. To confirm the importance of DNA methylation in hemJ expression, hemJ promoter variants with varying discriminator sequences were introduced into the wild type, followed by sll0729 deletion. The sll0729 deletion segregated in strains with the GGTC discriminator motif, resulting in wild-type-like pigmentation, whereas freshly prepared ∆sll0729 mutants with the native hemJ promoter exhibited the bluish phenotype. These findings demonstrate that hemJ is tightly regulated in Synechocystis and that N4-methylcytosine is essential for proper hemJ expression. Thus, cytosine N4-methylation is a relevant epigenetic marker in Synechocystis and likely other cyanobacteria.

• MeSH
• bakteriální proteiny metabolismus   genetika   MeSH
• epigeneze genetická * MeSH
• metylace DNA * MeSH
• mutace MeSH
• promotorové oblasti (genetika) * MeSH
• regulace genové exprese u bakterií MeSH
• Synechocystis * genetika   metabolismus   MeSH
• tetrapyrroly * metabolismus   biosyntéza   MeSH
• Publikační typ
• časopisecké články MeSH

5-Hydroxymethylcytosine (5-hmC) was recently identified as a relatively frequent base in eukaryotic genomes. Its physiological function is still unclear, but it is supposed to serve as an intermediate in DNA de novo demethylation. Using X-ray diffraction, we solved five structures of four variants of the d(CGCGAATTCGCG) dodecamer, containing either 5-hmC or 5-methylcytosine (5-mC) at position 3 or at position 9. The observed resolutions were between 1.42 and 1.99 Å. Cytosine modification in all cases influences neither the whole B-DNA double helix structure nor the modified base pair geometry. The additional hydroxyl group of 5-hmC with rotational freedom along the C5-C5A bond is preferentially oriented in the 3' direction. A comparison of thermodynamic properties of the dodecamers shows no effect of 5-mC modification and a sequence-dependent only slight destabilizing effect of 5-hmC modification. Also taking into account the results of a previous functional study [Münzel et al. (2011) (Improved synthesis and mutagenicity of oligonucleotides containing 5-hydroxymethylcytosine, 5-formylcytosine and 5-carboxylcytosine. Chem. Eur. J., 17, 13782-13788)], we conclude that the 5 position of cytosine is an ideal place to encode epigenetic information. Like this, neither the helical structure nor the thermodynamics are changed, and polymerases cannot distinguish 5-hmC and 5-mC from unmodified cytosine, all these effects are making the former ones non-mutagenic.

• MeSH
• 5-methylcytosin chemie   MeSH
• B-DNA chemie   MeSH
• cytosin analogy a deriváty   chemie   MeSH
• epigeneze genetická MeSH
• kationty chemie   MeSH
• krystalografie rentgenová MeSH
• molekulární modely MeSH
• termodynamika MeSH
• voda chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Hepatocyte nuclear factor 1 beta (HNF1B) is a transcription factor which plays a crucial role in nephronogenesis, and its germline mutations have been associated with kidney developmental disorders. However, the effects of HNF1B somatic exonic mutations and its role in the pathogenesis of kidney tumours has not yet been elucidated. Depending on the type of the tumour HNF1B may act as a tumour suppressor or oncogene, although the exact mechanism by which HNF1B participates in the process of cancerogenesis is unknown. Using an immunohistochemical approach, and methylation and mutation analysis, we have investigated the expression, epigenetic, and genetic changes of HNF1B in 130 cases of renal tumours (121 renal cell carcinomas, 9 oncocytomas). In the subset of clear cell renal cell carcinoma (ccRCC), decreased HNF1B expression was associated with a higher tumour grade and higher T stage. The mutation analysis revealed no mutations in the analysed samples. Promoter methylation was detected in two ccRCCs and one oncocytoma. The results of our work on a limited sample set suggest that while in papillary renal cell carcinoma HNF1B functions as an oncogene, in ccRCC and chRCC it may act in a tumour suppressive fashion.

• MeSH
• epigeneze genetická genetika   MeSH
• epigenomika metody   MeSH
• hepatocytární jaderný faktor 1-beta genetika   MeSH
• karcinom z renálních buněk genetika   patologie   MeSH
• ledviny patologie   MeSH
• lidé MeSH
• mutační analýza DNA metody   MeSH
• nádory ledvin genetika   patologie   MeSH
• promotorové oblasti (genetika) genetika   MeSH
• zárodečné mutace genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Recent genomic studies of sporadic clear cell renal cell carcinoma (ccRCC) have uncovered novel driver genes and pathways. Given the unequal incidence rates among men and women (male:female incidence ratio approaches 2:1), we compared the genome-wide distribution of the chromosomal abnormalities in both sexes. We observed a higher frequency for the somatic recurrent chromosomal copy number variations (CNVs) of autosomes in male subjects, whereas somatic loss of chromosome X was detected exclusively in female patients (17.1%). Furthermore, somatic loss of chromosome Y (LOY) was detected in about 40% of male subjects, while mosaic LOY was detected in DNA isolated from peripheral blood in 9.6% of them, and was the only recurrent CNV in constitutional DNA samples. LOY in constitutional DNA, but not in tumor DNA was associated with older age. Amongst Y-linked genes that were downregulated due to LOY, KDM5D and KDM6C epigenetic modifiers have functionally-similar X-linked homologs whose deficiency is involved in ccRCC progression. Our findings establish somatic LOY as a highly recurrent genetic defect in ccRCC that leads to downregulation of hitherto unsuspected epigenetic factors, and suggest that different mechanisms may underlie the somatic and mosaic LOY observed in tumors and peripheral blood, respectively.

• MeSH
• chromozomální delece * MeSH
• epigeneze genetická * MeSH
• histondemethylasy genetika   MeSH
• karcinom z renálních buněk genetika   MeSH
• lidé MeSH
• lidský chromozom Y * MeSH
• nádory ledvin genetika   MeSH
• regulace genové exprese u nádorů * MeSH
• variabilita počtu kopií segmentů DNA MeSH
• vedlejší histokompatibilní antigeny genetika   MeSH
• viabilita buněk genetika   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND: Obesity is a major health burden. Preadipocytes proliferate and differentiate in mature adipocytes in the adipogenic process, which could be a potential therapeutic approach for obesity. Deficiency of SIRT6, a stress-responsive protein deacetylase and mono-ADP ribosyltransferase enzyme, blocks adipogenesis. Mutants of SIRT6 (N308K/A313S) were recently linked to the in the long lifespan Ashkenazi Jews. In this study, we aimed to clarify how these new centenarian-associated SIRT6 genetic variants affect adipogenesis at the transcriptional and epigenetic level. METHODS: We analyzed the role of SIRT6 wild-type (WT) or SIRT6 centenarian-associated mutant (N308K/A313S) overexpression in adipogenesis, by creating stably transduced preadipocyte cell lines using lentivirus on the 3T3-L1 model. Histone post-translational modifications (PTM: acetylation, methylation) and transcriptomic changes were analyzed by mass spectrometry (LC-MS/MS) and RNA-Seq, respectively, in 3T3-L1 adipocytes. In addition, the adipogenic process and related signaling pathways were investigated by bioinformatics and biochemical approaches. RESULTS: Overexpression of centenarian-associated SIRT6 mutant increased adipogenic differentiation to a similar extent compared to the WT form. However, it triggered distinct histone PTM profiles in mature adipocytes, with significantly higher acetylation levels, and activated divergent transcriptional programs, including those dependent on signaling related to the sympathetic innervation and to PI3K pathway. 3T3-L1 mature adipocytes overexpressing SIRT6 N308K/A313S displayed increased insulin sensitivity in a neuropeptide Y (NPY)-dependent manner. CONCLUSIONS: SIRT6 N308K/A313S overexpression in mature adipocytes ameliorated glucose sensitivity and impacted sympathetic innervation signaling. These findings highlight the importance of targeting SIRT6 enzymatic activities to regulate the co-morbidities associated with obesity.

• MeSH
• adipogeneze * genetika   MeSH
• buňky 3T3-L1 * MeSH
• epigeneze genetická * genetika   MeSH
• histony metabolismus   genetika   MeSH
• lidé MeSH
• mutace MeSH
• myši MeSH
• obezita genetika   metabolismus   MeSH
• posttranslační úpravy proteinů genetika   MeSH
• sirtuiny * genetika   metabolismus   MeSH
• tukové buňky * metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Hepatocyte nuclear factor 1 beta (HNF1B) is transcription factor which plays a crucial role in the regulation of the development of several organs, but also seems to be implicated in the development of certain tumours, especially the subset of clear cell carcinomas of the ovary and kidney. Depending on the type of the tumour, HNF1B may act as either a tumour suppressor or an oncogene, although the exact mechanism by which HNF1B participates in the process of cancerogenesis is unknown. Using immunohistochemical approach and methylation and mutation analysis, we have investigated the expression, epigenetic, and genetic changes of HNF1B on 40 cases of colorectal adenomas and 105 cases of colorectal carcinomas. The expression of HNF1B was correlated with the benign or malignant behaviour of the lesion, given that carcinomas showed significantly lower levels of expression compared to adenomas. In carcinomas, lower levels of HNF1B expression were associated with recurrence and shortened disease-free survival. The mutation analysis revealed three somatic mutations (two frameshift and one nonsense) in the carcinoma sample set. Promoter methylation was detected in three carcinomas. These results suggest that in colorectal cancer, HNF1B may play a part in the pathogenesis and act in a tumour suppressive fashion.

• MeSH
• epigeneze genetická * MeSH
• hepatocytární jaderný faktor 1-beta genetika   MeSH
• kolorektální nádory genetika   metabolismus   patologie   MeSH
• lidé MeSH
• lokální recidiva nádoru genetika   metabolismus   patologie   MeSH
• metylace DNA * MeSH
• míra přežití MeSH
• nádorové biomarkery genetika   MeSH
• následné studie MeSH
• prognóza MeSH
• promotorové oblasti (genetika) MeSH
• regulace genové exprese u nádorů * MeSH
• senioři MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

We studied the in trans-silencing capacities of a transgene locus that carried the neomycin phosphotransferase II reporter gene linked to the 35S promoter in an inverted repeat (IR). This transgene locus was originally posttranscriptionally silenced but switched to a transcriptionally silenced epiallele after in vitro tissue culture. Here, we show that both epialleles were strongly methylated in the coding region and IR center. However, by genomic sequencing, we found that the 1.0 kb region around the transcription start site was heavily methylated in symmetrical and non-symmetrical contexts in transcriptionally but not in posttranscriptionally silenced epilallele. Also, the posttranscriptionally silenced epiallele could trans-silence and trans-methylate homologous transgene loci irrespective of their genomic organization. We demonstrate that this in trans-silencing was accompanied by the production of small RNA molecules. On the other hand, the transcriptionally silenced variant could neither trans-silence nor trans-methylate homologous sequences, even after being in the same genetic background for generations and meiotic cycles. Interestingly, 5-aza-2-deoxy-cytidine-induced hypomethylation could partially restore signaling from the transcriptionally silenced epiallele. These results are consistent with the hypothesis that non-transcribed highly methylated IRs are poor silencers of homologous loci at non-allelic positions even across two generations and that transcription of the inverted sequences is essential for their trans-silencing potential.

• MeSH
• alely MeSH
• epigeneze genetická MeSH
• financování organizované MeSH
• geneticky modifikované rostliny genetika   metabolismus   MeSH
• kanamycinkinasa genetika   metabolismus   MeSH
• metylace DNA MeSH
• nekódující RNA analýza   MeSH
• repetitivní sekvence nukleových kyselin MeSH
• reportérové geny MeSH
• tabák genetika   MeSH
• transgeny MeSH
• umlčování genů MeSH

• MeSH
• epigeneze genetická MeSH
• regulace genové exprese MeSH
• Publikační typ
• monografie MeSH

• Konspekt
• Biotechnologie. Genetické inženýrství
• NLK Obory
• genetika, lékařská genetika