scholarly journals The corepressor NCOR1 and OCT4 facilitate early reprogramming by suppressing fibroblast gene expression

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8952 ◽  
Author(s):  
Georgina Peñalosa-Ruiz ◽  
Klaas W. Mulder ◽  
Gert Jan C. Veenstra
Keyword(s):  
Transcriptional Repression ◽  
Somatic Cells ◽  
Chromatin Regulators ◽  
Highly Correlated ◽  
Induced Pluripotent ◽  
Transcriptional Corepressors ◽  
Transcriptomic Changes ◽  
Shed Light ◽  
Pluripotency Genes

Reprogramming somatic cells to induced pluripotent stem cells (iPSC) succeeds only in a small fraction of cells within the population. Reprogramming occurs in distinctive stages, each facing its own bottlenecks. It initiates with overexpression of transcription factors OCT4, SOX2, KLF4 and c-MYC (OSKM) in somatic cells such as mouse embryonic fibroblasts (MEFs). OSKM bind chromatin, silencing the somatic identity and starting the stepwise reactivation of the pluripotency programme. However, inefficient suppression of the somatic lineage leads to unwanted epigenetic memory from the tissue of origin, even in successfully generated iPSCs. Thus, it is essential to shed more light on chromatin regulators and processes involved in dissolving the somatic identity. Recent work characterised the role of transcriptional corepressors NCOR1 and NCOR2 (also known as NCoR and SMRT), showing that they cooperate with c-MYC to silence pluripotency genes during late reprogramming stages. NCOR1/NCOR2 were also proposed to be involved in silencing fibroblast identity, however it is unclear how this happens. Here, we shed light on the role of NCOR1 in early reprogramming. We show that siRNA-mediated ablation of NCOR1 and OCT4 results in very similar phenotypes, including transcriptomic changes and highly correlated high-content colony phenotypes. Both NCOR1 and OCT4 bind to promoters co-occupied by c-MYC in MEFs. During early reprogramming, downregulation of one group of somatic MEF-expressed genes requires both NCOR1 and OCT4, whereas another group of MEF-expressed genes is downregulated by NCOR1 but not OCT4. Our data suggest that NCOR1, assisted by OCT4 and c-MYC, facilitates transcriptional repression of genes with high expression in MEFs, which is necessary to bypass an early reprogramming block; this way, NCOR1 facilitates early reprogramming progression.

scholarly journals NCOR1 and OCT4 Facilitate Early Reprogramming by Co-Suppressing Fibroblast Gene Expression

2019 ◽  
Author(s):  
Georgina Peñalosa-Ruiz ◽  
Klaas W. Mulder ◽  
Gert Jan C. Veenstra
Keyword(s):  
Pluripotent Stem Cells ◽  
Somatic Cells ◽  
Embryonic Fibroblasts ◽  
Chromatin Regulators ◽  
Highly Correlated ◽  
Induced Pluripotent ◽  
Transcriptomic Changes ◽  
Shed Light ◽  
Pluripotency Genes

ABSTRACTReprogramming somatic cells to induced pluripotent stem cells (iPSC) succeeds only in a small fraction of cells within the population. Reprogramming occurs in distinctive stages, each facing its own bottlenecks. It initiates with overexpression of transcription factors OCT4, SOX2, KLF4 and c-MYC (OSKM) in somatic cells such as mouse embryonic fibroblasts (MEFs). OSKM bind chromatin, silencing the somatic identity and starting the stepwise reactivation of the pluripotency program. However, inefficient suppression of the somatic lineage leads to unwanted epigenetic memory from the tissue of origin, even in successfully generated iPSCs. Thus, it is essential to shed more light on chromatin regulators and processes involved in dissolving the somatic identity. Recent work characterized the role of transcriptional co-repressors NCOR1 and NCOR2 (also known as NCoR and SMRT), showing that they cooperate with c-MYC to silence pluripotency genes during late reprogramming stages. NCOR1/NCOR2 were also proposed to be involved in silencing fibroblast identity, however it is unclear how this happens. Here, we shed light on the role of NCOR1 in early reprogramming. We show that siRNA-mediated ablation of NCOR1 and OCT4 results in very similar phenotypes, including transcriptomic changes and highly correlated high content colony phenotypes.. Both NCOR1 and OCT4 bind to promoters co-occupied by c-MYC in MEFs. During early reprogramming, downregulation of one group of somatic MEF-expressed genes requires both NCOR1 and OCT4, whereas another group of MEF-expressed genes is downregulated by NCOR1 but not OCT4. Our data suggest that NCOR1, assisted by OCT4 and c-MYC, facilitates transcriptional inactivation of genes with high expression in MEFs, which need to be suppressed to bypass an early reprogramming block. This way, NCOR1 facilitates early reprogramming progression.

223 ISOLATION OF RABBIT PLURIPOTENCY GENES TO GENERATE RABBIT INDUCED PLURIPOTENT STEM CELLS

2012 ◽  
Vol 24 (1) ◽  
pp. 223 ◽  
Author(s):  
Z. Tancos ◽  
O. Ujhelly ◽  
M. K. Pirity ◽  
A. Dinnyes
Keyword(s):  
Stem Cells ◽  
Induced Pluripotent Stem Cells ◽  
Pluripotent Stem Cells ◽  
Somatic Cells ◽  
Blastocyst Stage ◽  
Promising Tool ◽  
Human Genes ◽  
Pluripotency Gene ◽  
Induced Pluripotent ◽  
Pluripotency Genes

Induced pluripotent stem cells (iPSC) technology, which allows direct reprogramming of somatic cells to a pluripotent state, is a promising tool for gene-function studies disease modelling, drug screening, toxicology tests and to generate knockout animal models. The goal of the current work was to close the gap in knowledge with regard to the molecular biological background for rabbit iPS work by isolating the putative pluripotency genes from the rabbit, based on the sequences published for other species. The sequence of known pluripotency genes (Oct4, Sox2, Klf4, c-Myc, Nanog) were analysed and primers designed based on the similarity of sequences. Sequences of each individual rabbit pluripotency gene was compared to other vertebrates (e.g. human, mouse, bovine) phylogenetically. Rabbit ESCs and blastocyst stage embryos were collected from superovulated rabbits to isolate total RNA. Genes of interest were amplified using RT-PCR and electrophoretically separated for cDNA fragment isolation. Isolated and subcloned cDNA fragments were sequenced and analysed. Our results showed that after restriction digestion the size of amplified and cloned rabbit Oct4, Sox2, Klf4, c-Myc and Nanog gene fragments correspond to the expected amplicon size. Furthermore, sequence confirmation by DNA sequencing has been completed in the case of Oct4, c-Myc, Klf4 and Nanog. The homology of these genes to that of their mouse and human orthologs were as follows: Oct4: at Na level 79% homologue to mouse, 85% homologue to human, at Aa level 81% homologue to mouse, 90% homologue to human; Klf4: at Na level 98% homologue to mouse, 85% homologue to human, at Aa level 95% homologue to mouse, 84% homologue to human; c-myc: at Na level 88% homologue to mouse, 92% homologue to human, at Aa level 91% homologue to mouse and 94% homologue to human; Nanog: at Na level 71% homologue to mouse, 78% homologue to human, at Aa level 55% homologue to mouse, 66% homologue to human. In conclusion, we have revealed differences at both Na and Aa level in all four major rabbit pluripotency gene sequences in comparison to their mammalian orthologs which might partially explain difficulties in generation of rabbit iPSC capable of germline transmission. Our further goal is to apply rabbit specific pluripotency genes to reprogram somatic cells and generate iPSC more efficiently than by using mouse or human genes. This work was supported by grants from Plurabbit, OMFB-00130/2010 ANR-NKTH; NKTH-OTKA-EU-7KP HUMAN-MB08-C-80-205; EU FP7 (AniStem, PIAP-GA-2011-286264PartnErS, PIAP-GA-2008-218205; InduStem, PIAP-GA-2008-230675; InduHeart, PEOPLE-IRG-2008-234390; InduVir, PEOPLE-IRG-2009-245808; PluriSys, HEALTH-2007-B-223485).

scholarly journals 5-Aza-2′-Deoxycytidine and Valproic Acid in Combination with CHIR99021 and A83-01 Induce Pluripotency Genes Expression in Human Adult Somatic Cells

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1909
Author(s):  
Alain Aguirre-Vázquez ◽  
Luis A. Salazar-Olivo ◽  
Xóchitl Flores-Ponce ◽  
Ana L. Arriaga-Guerrero ◽  
Dariela Garza-Rodríguez ◽  
...  
Keyword(s):  
Valproic Acid ◽  
Disease Modeling ◽  
Morphological Changes ◽  
Somatic Cells ◽  
Ectopic Expression ◽  
Dermal Fibroblasts ◽  
Klf4 Expression ◽  
Genes Expression ◽  
Induced Pluripotent ◽  
Pluripotency Genes

A generation of induced pluripotent stem cells (iPSC) by ectopic expression of OCT4, SOX2, KLF4, and c-MYC has established promising opportunities for stem cell research, drug discovery, and disease modeling. While this forced genetic expression represents an advantage, there will always be an issue with genomic instability and transient pluripotency genes reactivation that might preclude their clinical application. During the reprogramming process, a somatic cell must undergo several epigenetic modifications to induce groups of genes capable of reactivating the endogenous pluripotency core. Here, looking to increase the reprograming efficiency in somatic cells, we evaluated the effect of epigenetic molecules 5-aza-2′-deoxycytidine (5AZ) and valproic acid (VPA) and two small molecules reported as reprogramming enhancers, CHIR99021 and A83-01, on the expression of pluripotency genes and the methylation profile of the OCT4 promoter in a human dermal fibroblasts cell strain. The addition of this cocktail to culture medium increased the expression of OCT4, SOX2, and KLF4 expression by 2.1-fold, 8.5-fold, and 2-fold, respectively, with respect to controls; concomitantly, a reduction in methylated CpG sites in OCT4 promoter region was observed. The epigenetic cocktail also induced the expression of the metastasis-associated gene S100A4. However, the epigenetic cocktail did not induce the morphological changes characteristic of the reprogramming process. In summary, 5AZ, VPA, CHIR99021, and A83-01 induced the expression of OCT4 and SOX2, two critical genes for iPSC. Future studies will allow us to precise the mechanisms by which these compounds exert their reprogramming effects.

The Role of Zinc in Thyroid Hormones Metabolism

2019 ◽  
Vol 89 (1-2) ◽  
pp. 80-88 ◽  
Author(s):  
Juliana Soares Severo ◽  
Jennifer Beatriz Silva Morais ◽  
Taynáh Emannuelle Coelho de Freitas ◽  
Ana Letícia Pereira Andrade ◽  
Mayara Monte Feitosa ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Scientific Evidence ◽  
Thyroid Stimulating Hormone ◽  
Zinc Transporters ◽  
Serum Concentrations ◽  
Metabolic Adaptations ◽  
Serum T3 ◽  
Regulatory Effects ◽  
Shed Light

Abstract. Thyroid hormones play an important role in body homeostasis by facilitating metabolism of lipids and glucose, regulating metabolic adaptations, responding to changes in energy intake, and controlling thermogenesis. Proper metabolism and action of these hormones requires the participation of various nutrients. Among them is zinc, whose interaction with thyroid hormones is complex. It is known to regulate both the synthesis and mechanism of action of these hormones. In the present review, we aim to shed light on the regulatory effects of zinc on thyroid hormones. Scientific evidence shows that zinc plays a key role in the metabolism of thyroid hormones, specifically by regulating deiodinases enzymes activity, thyrotropin releasing hormone (TRH) and thyroid stimulating hormone (TSH) synthesis, as well as by modulating the structures of essential transcription factors involved in the synthesis of thyroid hormones. Serum concentrations of zinc also appear to influence the levels of serum T3, T4 and TSH. In addition, studies have shown that Zinc transporters (ZnTs) are present in the hypothalamus, pituitary and thyroid, but their functions remain unknown. Therefore, it is important to further investigate the roles of zinc in regulation of thyroid hormones metabolism, and their importance in the treatment of several diseases associated with thyroid gland dysfunction.

The Adult as Foe or Friend?: Childism in Guus Kuijer's Criticism and Fiction

2013 ◽  
Vol 6 (2) ◽  
pp. 205-217 ◽  
Author(s):  
Vanessa Joosen
Keyword(s):  
Children's Literature ◽  
Children’S Literature ◽  
Age Groups ◽  
Children's Books ◽  
Children’S Books ◽  
Memorial Award ◽  
Adult Reader ◽  
Shed Light ◽  
Selection Of

Compared to the attention that children's literature scholars have paid to the construction of childhood in children's literature and the role of adults as authors, mediators and readers of children's books, few researchers have made a systematic study of adults as characters in children's books. This article analyses the construction of adulthood in a selection of texts by the Dutch author and Astrid Lindgren Memorial Award winner Guus Kuijer and connects them with Elisabeth Young-Bruehl's recent concept of ‘childism’ – a form of prejudice targeted against children. Whereas Kuijer published a severe critique of adulthood in Het geminachte kind [The despised child] (1980), in his literary works he explores a variety of positions that adults can take towards children, with varying degrees of childist features. Such a systematic and comparative analysis of the way grown-ups are characterised in children's texts helps to shed light on a didactic potential that materialises in different adult subject positions. After all, not only literary and artistic aspects of children's literature may be aimed at the adult reader (as well as the child), but also the didactic aspect of children's books can cross over between different age groups.

Tax evasion in the medical profession An Empirical Study in the General Tax Authority in Iraq

2019 ◽  
Vol 118 (11) ◽  
pp. 80-88
Author(s):  
Ramyar Rzgar Ahmed ◽  
Hawkar Qasim Birdawod ◽  
S. Rabiyathul Basariya
Keyword(s):  
Tax Evasion ◽  
Income Tax ◽  
Medical Profession ◽  
Great Influence ◽  
Tax Law ◽  
Degree Of Confidence ◽  
Medical Professions ◽  
Shed Light

The study dealt with tax evasion in the medical profession, where the problem was the existence of many cases of tax evasion, especially tax evasion in the income tax of medical professions. The aim of the study is to try to shed light on the phenomenon of tax evasion and the role of the tax authority in the development of controls and means that reduce the phenomenon of tax evasion. The most important results of the low level of tax awareness and lack of knowledge of the tax law and the unwillingness to read it and the sense of taxpayers unfairness of the tax all lead to an increase in cases of tax evasion and in suggested tightening control and follow-up on the offices of auditors, through the investigation and auditing The reports of certified accountants and the use of computers for this purpose in order to raise the degree of confidence in these reports and bring them closer to the required truth and coordination and cooperation with the Union of Accountants and Auditors and inform them about each case of violations of the auditors and accountants N because of its great influence in the rejection of the organization of the accounts and not to ratify fake accounts lead to show taxpayers accounts on a non-truth in order to tax evasion.

Methyl mercury in the dutch rhine delta

1994 ◽  
Vol 30 (10) ◽  
pp. 213-219 ◽  
Author(s):  
Hendrik Pieters ◽  
Victor Geuke
Keyword(s):  
Suspended Matter ◽  
Methyl Mercury ◽  
Mercury Contamination ◽  
Benthic Organisms ◽  
Considerable Decrease ◽  
Continuous Sedimentation ◽  
Highly Correlated ◽  
High Level ◽  
Almost All

Samples of yellow eel from various locations in the Dutch Rhine area have been analyzed for trend monitoring of mercury since 1977. In the western Rhine delta mercury levels in eels have hardly changed since the seventies, whereas in the eastern part of the Dutch Rhine area a considerable decrease of mercury concentrations in eel has occurred. Because of continuous sedimentation of contaminated suspended matter transported from upstream regions, accumulation rates and concentrations of mercury in eel in the western Rhine delta remained at a relatively high level. Analyses of methyl mercury in biota have been performed to elucidate the role of methyl mercury in the mercury contamination of the Dutch Rhine ecosystem. Low percentages of methyl mercury were observed in zooplankton (3 to 35%). In benthic organisms (mussels) percentages of methyl mercury ranged from 30 to 57%, while in fish species and liver of aquatic top predator birds almost all the mercury was present in the form of methyl mercury (> 80%). During the period 1970-1990 mercury concentrations of suspended matter in the eastern Rhine delta have drastically decreased. These concentrations seemed to be highly correlated with mercury concentrations of eel (R = 0.84). The consequences of this relation are discussed.

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