Search results for "chromatin"
showing 10 items of 490 documents
Epigenetic Control of the foxp3 Locus in Regulatory T Cells
2007
Compelling evidence suggests that the transcription factor Foxp3 acts as a master switch governing the development and function of CD4+ regulatory T cells (Tregs). However, whether transcriptional control of Foxp3 expression itself contributes to the development of a stable Treg lineage has thus far not been investigated. We here identified an evolutionarily conserved region within the foxp3 locus upstream of exon-1 possessing transcriptional activity. Bisulphite sequencing and chromatin immunoprecipitation revealed complete demethylation of CpG motifs as well as histone modifications within the conserved region in ex vivo isolated Foxp3+CD25+CD4+ Tregs, but not in naïve CD25−CD4+ T cells. …
INTACT vs. FANS for Cell-Type-Specific Nuclei Sorting: A Comprehensive Qualitative and Quantitative Comparison
2021
Increasing numbers of studies seek to characterize the different cellular sub-populations present in mammalian tissues. The techniques “Isolation of Nuclei Tagged in Specific Cell Types” (INTACT) or “Fluorescence-Activated Nuclei Sorting” (FANS) are frequently used for isolating nuclei of specific cellular subtypes. These nuclei are then used for molecular characterization of the cellular sub-populations. Despite the increasing popularity of both techniques, little is known about their isolation efficiency, advantages, and disadvantages or downstream molecular effects. In our study, we compared the physical and molecular attributes of sfGFP+ nuclei isolated by the two methods—INTACT and FAN…
Co-option of Neutrophil Fates by Tissue Environments
2020
Classically considered short-lived and purely defensive leukocytes, neutrophils are unique in their fast and moldable response to stimulation. This plastic behavior may underlie variable and even antagonistic functions during inflammation or cancer, yet the full spectrum of neutrophil properties as they enter healthy tissues remains unexplored. Using a new model to track neutrophil fates, we found short but variable lifetimes across multiple tissues. Through analysis of the receptor, transcriptional, and chromatin accessibility landscapes, we identify varying neutrophil states and assign non-canonical functions, including vascular repair and hematopoietic homeostasis. Accordingly, depletion…
Y chromosomes: born to be destroyed
2005
Suppression of recombination is the prerequisite for stable genetically determined sex systems. A consequence of suppression of recombination is the strong bias in the distribution of transposable elements (TEs), mostly retrotransposons. Our results and those from others indicate that the major force driving the degeneration of Y chromosomes are retrotransposons in remodelling former euchromatic chromosome structures into heterochromatic ones. We put forward the following hypotheses. (1) A massive accumulation of retrotransposons occurs early in non-recombining regions. (2) Heterochromatic nucleation centres are formed as a genomic defence mechanism against invasive parasitic elements. The …
In vivo GSH depletion induces c-myc expression by modulation of chromatin protein complexes.
2009
Abstract We hypothesize that glutathione (GSH) fluctuations could have a prominent role in the modulation of c-myc expression through a mechanism affecting chromatin remodeling complexes. This could lead to an open chromatin structure accessible to transcription factors. We studied the in vivo effect of GSH depletion on these complexes bound to the c-myc promoter in the liver of l-buthionine-(S,R)-sulfoximine (BSO)-treated rats. Using chromatin immunoprecipitation we found that 3 h after BSO treatment the repressing complexes Id2 and Sin3A (part of a histone–deacetylase complex) were released from the c-myc promoter. STAT3 was phosphorylated and associated with its coactivator p300 with int…
Chromosome Analysis and rDNA FISH in The Stag Beetle Dorcus Parallelipipedus L. (Coleoptera: Scarabaeoidea: Lucanidae)
2001
In the present work the chromosome complement (2n = 18; 8AA + XY) of the stag beetle Dorcus parallelipipedus L. (Scarabaeoidea: Lucanidae) is analyzed using conventional Giemsa staining, banding techniques and ribosomal fluorescent in situ hybridization (rDNA FISH). rDNA FISH remains the unique tool for providing a clear-cut identification of Nucleolar Organizer Regions (NORs) when conventional banding methods such as silver- and CMA3-staining proved to be inadequate. The dull, homogeneous CMA3 fluorescence of all chromosomes indicates the absence of markedly GC rich compartmentalized regions in D. parallelipipedus genome. Silver impregnation inadequacy in detecting NOR regions is to be sou…
Different micrococcal nuclease cleavage patterns characterize transcriptionally active and inactive sea-urchin histone genes.
1986
Micrococcal nuclease (MNase) and DNaseI have made a great contribution to our present understanding of the structural organization of the eucaryotic genome [l - 31. The enhanced sensitivity of active portions of the genome to DNaseI gave, in fact, the first indication of differences in the nucleoproteic arrangement of the transcribed as compared to the silent DNA regions [4]. The use of MNase, as a probe of the chromatin organization of specific genes in the active and inactive state, provided additional evidence for this and further showed that the packing of several coding segments of DNA in a regular array of nucleosomal particles is severely but reversibly affected by the transcriptiona…
Nuclear fos domains in transcriptionally activated supraoptic nucleus neurons
1993
This study has analysed by light and electron microscopy immunolocalization the nuclear pattern of distribution of Fos-related proteins in supraotic neurons. Two experimental models of transcriptional activation have been used: sustained, global transcriptional activation, at relatively near physiological conditions, by six days of chronic intermittent salt loading; and superinduction of c-fos gene by this salt loading regime plus cycloheximide treatment for 4 h. In the first condition, the ultrastructural analysis showed a distribution of Fos-like immunoreactivity on the reticular network of dispersed chromatin that extends between the nucleolar surface and the nuclear envelope, whereas th…
RNAPol-ChIP: a novel application of chromatin immunoprecipitation to the analysis of real-time gene transcription.
2004
We describe a procedure, RNAPol-ChIP, to measure actual transcriptional rate. It consists of the detection, by chromatin immunoprecipitation (ChIP), of RNA polymerase II within the coding region of genes. To do this, the DNA immunoprecipitated with polymerase antibodies is analysed by PCR, using an amplicon well within the coding region of the desired genes to avoid interferences with polymerase paused at the promoter. To validate RNAPol-ChIP, we compare our results to those obtained by classical methods in several genes induced during either liver regeneration or acute pancreatitis. When short half-life mRNA genes are studied (e.g. c-fos and egr1), RNAPol-ChIP gives results similar to thos…
The human X chromosome is enriched for germline genes expressed in premeiotic germ cells of both sexes.
2006
The role of X-chromosomal genes in spermatogenesis has been subject to a number of studies in different organisms. Recently, it was proposed that the X chromosome has a predominant role in premeiotic stages of mammalian spermatogenesis. We analyzed the expression of a representative set of 17 X-linked and 48 autosomal germline-restricted genes in different stages of human germ cell development. In accordance with data from other species, we show that the human X chromosome is indeed significantly enriched for genes activated in premeiotic stages of spermatogenesis. In contrast to recent studies, however, we found that expression of these genes is not restricted to spermatogenesis, but is ac…