Epigenetics and genetics of hematopoietic stem cells heterogeneity

Abstract In diploid eukaryotic organisms, most genes are expressed biallelically. However, there are exceptions where the expression occurs in a monoallelic pattern that results from a differential allele-specific transcription based on the different epigenetic marking of the two alleles. At the level of cells, there are three classes of monoallelic expression regulated by epigenetic mechanisms: parent-of-origin imprinting, X chromosome inactivation (XCI), and random autosomal monoallelic expression (RMAE). Biased repopulations obtained from single-cell transplantation assays revealed that the pool of hematopoietic stem cells (HSCs) is heterogeneous, reflecting the epigenetic differences of individual cells. According to a model in which the allele-specific expression patterns are established during differentiation in embryonic stem cells and are stably propagated through cell divisions, it is assumed that HSCs carry genes (and alleles) with these stable epigenetic marks. Therefore, the analysis of epigenetic states in the stem cell population at the clonal level is necessary to understand its heterogeneity and diversity. Here we evaluated for the first time the persistence of allele-specific epigenetic states in the hematopoietic system in vivo using allelic imbalance as a readout. We created a monoclonal hematopoietic system in mice by single HSC transplantation and then analyzed the emerging lymphoid progeny using a genome-wide transcriptomics approach. We revealed that in the single-HSC derived hematopoietic cells, XCI is stably maintained through extensive proliferation and differentiation, whereas the vast majority of autosomal genes lack the stable clonal patterns of random monoallelic expression. This finding shows that the recurrent parallels between XCI and RMAE are misleading, suggesting that different mechanisms underlie these two classes of monoallelic expression. Additionally, we show that this in vivo clonal approach, which is free of genetic manipulation, can replace the artificial strategies that have been used to study tissue-specific XCI. Finally, stable allele-specific expression patterns were found in a rare number of genes (14 genes, <0.2%) in the progeny of a single HSC, indicating that these patterns were already present in the original HSC used for transplantation. However, the number of genes with stable monoallelic expression in cells that underwent differentiation steps is much lower than the numbers previously reported in studies using clonal cell lines in vitro without extensive differentiation (~2–15%). To reconcile these observations, we propose that most allele-specific expression patterns in autosomal genes are metastable and can be erased and reestablished at different differentiation stages.Resumo Nos organismos eucarióticos diplóides, a maioria dos genes são expressos bialelicamente. No entanto, existem excepções em que, ao nível das células, a expressão ocorre num padrão monoalélico que resulta de uma transcrição diferencial dos alelos de base epigenética. Existem três classes de expressão monoalélica regulada por mecanismos epigenéticos: imprinting de origem parental, inactivação do cromossoma X (XCI*) e expressão aleatória monoalélica autossómica (RMAE). Populações enviesadas obtidas a partir de ensaios de transplante de uma única célula revelaram que o conjunto de células estaminais hematopoiéticas (HSCs) é heterogéneo, reflectindo as diferenças epigenéticas de células individuais. Segundo um modelo em que os padrões da expressão específica de alelos são estabelecidos durante a diferenciação de células estaminais embrionárias e são propagados depois de forma estável através de divisões celulares, as HSCs carregam genes (e alelos) com marcas epigenéticas estáveis. A análise a nível clonal dos estados epigenéticos das células estaminais é necessária para entender a sua heterogeneidade e diversidade. Nesta tese, avaliamos pela primeira vez a persistência de estados epigenéticos entre os alelos no sistema hematopoiético in vivo usando o desequilíbrio da expressão alélica como ferramenta de leitura. O trabalho baseou-se na criação de um sistema hematopoiético monoclonal em ratinho por transplante de uma única HSC e no subsequente estudo da progenia linfóide emergente por análise transcriptómica de todo o genoma. Nas células hematopoiéticas resultantes de uma única HSC, verificámos que a XCI é mantida de forma estável após extensa proliferação e diferenciação, enquanto a vasta maioria dos genes autossómicos não estão sob RMAE. Assim, os paralelismos recorrentes na literatura entre XCI e RMAE são enganosos, porque estes dois fenómenos não têm a mesma estabilidade e serão regulados por diferentes mecanismos. Além disso, demonstramos que esta abordagem clonal com base num sistema sem manipulação genética pode ser uma estratégia para estudar a XCI específica de tecidos in vivo. Por fim, um padrão de RMAE foi encontrado num número raro de genes (14 genes, <0,2% do total) em células linfóides resultantes de uma única HSC, indicando que esses padrões já estavam presentes na HSC original usada no transplante. No entanto, o número de genes com RMAE em células que passaram por etapas de diferenciação é muito menor do que o número relatado anteriormente em estudos usando linhagens celulares clonais in vitro sem diferenciação extensa (~2–15%). Para conciliar estas observações, propomos que a maioria dos padrões de RMAE são meta-estáveis, isto é, passíveis de eliminação e restauração em diferentes estados de diferenciação

The Effect of Strategic Development on the Competitive Status: The Case of Equinor

Master of Science i global ledelse - Nord universitet 202

The Effects of Low Doses of Ionizing Radiation Upon the Micromorphology and Functional State of Cell Surface

The cellular membrane as one of the targets of ionizing radiation might play an important role in the development and modification of radiation-induced alterations after low doses. The present paper reviews the micromorphological and functional changes of plasma membranes of irradiated blood and cultured cells with special emphasis on the surface conditions: lectin binding, negative surface charges. The review is completed by our own studies on distribution of positive surface charges and the bindings of two lectins, the Concanavalin A and the wheat germ agglutinin. It was found that the decrease of negative surface charges is unconcomitant with appearance of domains exposing positive ones, particularly on the surfaces of rufflings. The distribution of Concanavalin A binding sites turned from a uniform distribution to a polarized one, especially on apical regions where it appeared in large aggregates. The polarity in localization of wheat germ agglutinin on untreated fibroblasts observed in our experiments ceased shortly after irradiation

Effects of Low Energy Beta-Irradiation from Tritiated Water on the Morphology of 3T3 Fibroblasts

Cellular alterations of cultured 3T3 cells irradiated with beta-rays from tritiated water were studied by scanning and transmission electron microscopy. We observed decreased negative surface charges, vacuolization of rough endoplasmic reticulum and Golgi-complex, degeneration of mitochondria, increase of lysosomal activity and changes in distribution and amount of microfilaments in the irradiated cells, that parallelled changes in cell shape

Molecular Tuning of the Magnetic Response in Organic Semiconductors

The tunability of high-mobility organic semi-conductors (OSCs) holds great promise for molecular spintronics. In this study, we show this extreme variability - and therefore potential tunability - of the molecular gyromagnetic coupling ("g-") tensor with respect to the geometric and electronic structure in a much studied class of OSCs. Composed of a structural theme of phenyl- and chalcogenophene (group XVI element containing, five-membered) rings and alkyl functional groups, this class forms the basis of several intensely studied high-mobility polymers and molecular OSCs. We show how in this class the g-tensor shifts, $\Delta g$, are determined by the effective molecular spin-orbit coupling (SOC), defined by the overlap of the atomic spin-density and the heavy atoms in the polymers. We explain the dramatic variations in SOC with molecular geometry, chemical composition, functionalization, and charge life-time using a first-principles theoretical model based on atomic spin populations. Our approach gives a guide to tuning the magnetic response of these OSCs by chemical synthesis

Polarized Membrane Domains of Fibroblasts

Data on the heterogeneous distribution of various membrane domains on the surface of fibroblasts are reviewed. Polarized localization of negative charges is demonstrated and new results on the development and maintenance of polarity in primary human fibroblasts are presented. Cell membrane heterogeneity in fibroblasts and in other cells is compared. Our results indicate that the regional localization of membrane domains of fibroblasts, and their dependence on cell movement and cell contacts is in several aspects similar to that described for epithelial cells

Socio-cultural rehabilitation of children with ASD in the State Darwin Museum. Program «Others»

The State Darwin Museum has been carrying out work on the socio-cultural rehabilitation of people with disabilities with museum facilities for the many years. The museum is actively developing the direction on the complex adaptation for visitors with autism spectrum disorders

Professional Burnout of Faculty Members of Higher Educational Institutions

The article is devoted to the analysis of professional burnout of the academic staff of a number of Moscow higher educational institutions. This problem most often affects residents of large cities, due to the intense rhythm of the city and lack of time for personal life, wasted on the way from home to work and back. The empirical basis of the study was the results of a sociological study conducted by the authors in 2019 on the basis of FSBEI HE Russian State Social University (RSSU), FSBEI HE Moscow State Humanitarian and Economic University (MSHEU), and FSBEI HE Russian State University of Tourism and Service (RSUTS). The problem of the deteriorated psychological state of teachers leading to professional burnout is poorly developed and causes increased research and practical interest, and gives rise to the practical need to improve the development of measures for the prevention and avoidance of burnout. All the above makes further research activity highly relevant, and may be extremely necessary in some universities. This is evidenced by the results of the study.: It is of vital importance to take measures to prevent professional burnout of the academic staff and to develop a strategy for a teacher-based approach considering personal qualities and potential. The administration should consider psychological, spiritual, and labor characteristics of teachers for the formation and distribution of individual schedules of teachers. The Novelty of the study is in investigating the professional burnout of the academic staff of an institution in Moscow

Effect of X-Irradiation on Adenylate Cyclase Activity and Cyclic AMP Content of Primary Human Fibroblasts

Ionizing radiation provokes an increase of the cAMP level in several organs and body fluids. After reviewing the relevant literature we present the results of our own experiments on primary human fibroblasts. X-irradiation at doses of 0.5 and 2.5 Gy in vitro evoked a rapid and reversible increase of adenylate cyclase enzyme activity. A significant increase in cAMP level of these cells was also observed. Adenylate cyclase was usually localized basolaterally on the surface of unirradiated cells, while irradiation resulted in a modification of distribution, i.e., the enzyme activity also appeared in apical localization