Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 4

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

Search:
in the keywords:  CHROMATIN
help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1

Regulation of cytokine transcription in the context of chromatin

100%
Nikolajczyk B.
Archivum Immunologiae et Therapiae Experimentalis
|
2006
|
vol. 54
|
issue 5
295-305
EN
Understanding the transcriptional regulation of an important class of innate and adaptive immune system effector molecules, the cytokines, is increasingly important given the promise cytokine regulation holds for treating various autoimmune and inflammatory diseases. Studies defining the mechanisms regulating cytokine transcription initially focused on identifying the cis-acting elements and trans-acting factors that activate cytokine promoters and enhancers. In the past, these studies were largely completed in the absence of constraints instituted by cellular chromatin. Over the past decade it has become obvious that changes in chromatin accessibility critically control, rather than simply correlate with, the transcriptional activation of most genes, including cytokines. Hence candidate transcriptional activators are being re-evaluated for potency in the context of cellular chromatin. Several distinct mechanisms for manipulating the generally repressive context of chromatin have been identified for cytokine genes. Most recently, single nucleotide polymorphisms in cytokine transcriptional regulatory elements have been shown to play measurable roles in regulating cytokine levels in the context of naturally selected haplotypes. Overall, subtle differences in DNA sequence and nucleoprotein complex composition, including protein post-translational modification, come together in cell type-specific combinations to explain the normal variation in cytokine transcription throughout the human populace.
2

Histone deacetylase complexes: implications for plants

100%
Lawit S. J., Czarnecka-Verner E.
|
EN
Post-translational modifications of histone tails have dramatic ramifications on a variety of vital cellular functions. Removal of the acetyl groups from lysine residues is catalyzed by histone deacetylases (HDs). Many HDs are known to be components of multiprotein complexes such as SIN3 and NuRD that are involved in chromatin condensation and gene regulation. Plants contain a highly elaborated set of HDs with four distinct classes of these enzymes. Plant HDs have been implicated to play roles in transgene silencing, rDNA regulation, gene expression, and many developmental processes. Seventeen Arabidopsis HDs are apparent in Genbank as are numerous putative HD-interacting partners. Maize HDs have been extensively characterized biochemically and the use of powerful genetic tools currently available in Arabidopsis is rapidly accelerating the base of knowledge on the control circuitry of plant chromatin.
3
Content available remote

Chromatin structure and transcriptional activity of MAG gene

100%
Konat G. W.
Acta Neurobiologiae Experimentalis
|
1996
|
vol. 56
|
issue 1
281-285
EN
Myelin associated glycoprotein (MAG) is an essential component of the periaxonal architecture of the myelin sheath. Because of its potent neurite growth repressive activity, MAG is also likely to play an important role in axonal guidance during the CNS development, and to be responsible for abortive neuronal regeneration in adult CNS. The MAG gene chromatin from approximately -1.6 to +0.6 kb features MNase hypersensitivity that maydelineate the gene control region. The proximal upstream region of the gene is organized into an array of five nucleosomes with hypersensitive linkers. The core promoter is located within the first upstream linker that becomes highly hypersensitive in the course of oligodendrocyte differentiation. The adjacent upstream region contains positive and negative enhancers that are likely to streamline oligodendrocyte specific expession of the gene. The TATA-less core promoter contains novel, as yet uncharacterized initiator elements that direct the assembly of transcriptional complexes. The promoter appears to be controlled by both, the addition of activating trans-factors as progenitor cells differentiate into mature oligodendrocyte. The developmental activation of the gene is also concomitant with profound DNA demethylation that may provide auxiliary regulatory mechanisms. Hence, the upregulation of the MAG gene is differentiating oligodendrocytes entails chromantic remodeling as well as changes in the assortment of nuclear trans-factors.
4

Artificial activation of porcine oocytes in somatic cell cloning procedure - biotechnological, genetic and epigenetic aspects

88%
Samiec M.
Biotechnologia
|
2009
|
issue 3
85-110
EN
In the somatic cell cloning of pigs, nuclear transfer-derived oocytes are artificially stimulated with the use one of the three experimental protocols: 1) electrical, chemical or physicochemical delayed activation (i.e., post-activation); 2) simultaneous fusion and electrical activation (SF-EA) or simultaneous electrofusion and physicochemical activation, as well as 3) chemical sequential (combined) electrical and chemical activation. In the first activation protocol, somatic cell nuclei at G0/G1 or G2/M stages are introduced into enucleated Metaphase II oocytes (ooplasts), which are activated 30 minutes to several hours after nuclear transfer. In the second activation protocol, somatic cell nuclei at G1 or G0 stage are introduced into non-activated Metaphase II ooplasts and simultaneously obtained clonal nuclear-cytoplasmic hybrids are activated. In turn, the third activation protocol includes the SF-EA followed by an additional treatment of the reconstituted oocytes with chemical factors, which is initiated after a 1.5-2-h delay. The concentration of calcium cations in the fusion/activation medium affects not only the transition from meiotic to mitotic control of cell cycle of clonal cybrids, but also the degree of ploidy of reconstructed zygotes as a result of both emission of second polar body and formation of pseudopronucleus/pseudopronuclei. The artificial stimulation of reconstituted oocytes also determines the processes of architectural remodeling and epigenetic reprogramming of donor cell nuclei in nuclear-transferred embryos. Moreover, the transcriptional and translational activity of genes (eg Oct-3/Oct-4) that are crucial for preimplantation development of porcine cloned embryos is dependent on physicochemical parameters of calcium oscillations induced by activation of clonal nuclear-cytoplasmic hybrids.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.