共查询到20条相似文献,搜索用时 15 毫秒
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Foshay KM Looney TJ Chari S Mao FF Lee JH Zhang L Fernandes CJ Baker SW Clift KL Gaetz J Di CG Xiang AP Lahn BT 《Molecular cell》2012,46(2):159-170
It is a long-held paradigm that cell fusion reprograms gene expression but the extent of reprogramming and whether it is affected by the cell types employed remain unknown. We recently showed that the silencing of somatic genes is attributable to either trans-acting cellular environment or cis-acting chromatin context. Here, we examine how trans- versus cis-silenced genes in a somatic cell type behave in fusions to another somatic cell type or to embryonic stem cells (ESCs). We demonstrate that while reprogramming of trans-silenced somatic genes occurs in both cases, reprogramming of cis-silenced somatic genes occurs only in somatic-ESC fusions. Importantly, ESCs reprogram the somatic genome in two distinct phases: trans-reprogramming occurs rapidly, independent of DNA replication, whereas cis-reprogramming occurs with slow kinetics requiring DNA replication. We also show that pluripotency genes Oct4 and Nanog are cis-silenced in somatic cells. We conclude that cis-reprogramming capacity is a fundamental feature distinguishing ESCs from somatic cells. 相似文献
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Summary Various aspects of somatic embryogenesis in carrot suspension cultures were reviewed on the basis of results obtained in our
laboratory. We have established high-frequency and synchronous somatic embryogenesis systems needed for biochemical and molecular
analysis. Using these systems, four phases of somatic embryogenesis were identified. The importance of expression of polarities
in these phases, particularly from single cells to embryogenic cell clusters, in determining somatic embryogenesis, is emphasized.
At the molecular level, genes expressed during somatic embryogenesis were described, and they were classified into three categories:
(1) genes involved in cell division, (2) genes involved in organ formation and (3) genes specific for the process of somatic
embryogenesis. From the results obtained, it is concluded that discrete developmental phases in carrot somatic embryogenesis
are characterized by distinct biochemical and molecular events, but much remains to be understood. 相似文献
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Physical mapping of genes in somatic cell radiation hybrids by comparative genomic hybridization to cDNA microarrays 总被引:1,自引:0,他引:1
Lin JY Pollack JR Chou FL Rees CA Christian AT Bedford JS Brown PO Ginsberg MH 《Genome biology》2002,3(6):research0026.1-research00267
Background
Somatic cell mutants can be informative in the analysis of a wide variety of cellular processes. The use of map-based positional cloning strategies in somatic cell hybrids to analyze genes responsible for recessive mutant phenotypes is often tedious, however, and remains a major obstacle in somatic cell genetics. To fulfill the need for more efficient gene mapping in somatic cell mutants, we have developed a new DNA microarray comparative genomic hybridization (array-CGH) method that can rapidly and efficiently map the physical location of genes complementing somatic cell mutants to a small candidate genomic region. Here we report experiments that establish the validity and efficacy of the methodology. 相似文献6.
Varshaver NB 《Molekuliarnaia biologiia》2002,36(2):328-337
The history of somatic cell genetics from the late 1950s to the present day is considered. Studies in this field provided for the elucidation of numerous fundamental and applied problems, including spontaneous mutagenesis, gene mapping with somatic cell hybrids, and genetic mechanisms of carcinogenesis (e.g., cell protooncogenes, oncogenes, and tumor suppressor genes were revealed). The knocking-out technique allowed the effects of various genes to be analyzed. 相似文献
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Somatic cell genetics and flow cytometry 总被引:1,自引:0,他引:1
Human genes coding cell surface molecules can be introduced into mouse host cells using a variety of somatic cell genetic techniques. Because these human gene products can be detected using indirect immunofluorescence on viable cells, the genes themselves can be monitored and manipulated using flow cytometry and sorting. In this paper, we review ways that we have used cell sorting to develop a somatic cell genetic analysis of the human cell surface. 相似文献
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Gurdon JB 《Journal of biosciences》2005,30(1):11-14
When nuclei of somatic cells are transplanted to enucleated eggs ofXenopus, a complete reprogramming of nuclear function can take place. To identify mechanisms of nuclear reprogramming, somatic nuclei
can be transplanted to growing meiotic oocytes ofXenopus, and stem cell genes activated without DNA replication. The combination of somatic cell nuclear transfer with morphogen signalling
and the community effect may lead towards the possibility of cell replacement therapy. When mechanisms of nuclear reprogramming
are understood, it may eventually be possible to directly reprogramme human somatic cell nuclei without the use of eggs. 相似文献
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N I Shapiro 《Genetika》1975,11(6):159-176
A review of recent advances in genetics of somatic cells is given in the article. It contains three sections: 1) hybridization of somatic cells and its application to the mapping of genes and to the study of gene action; 2) relation of somatic cell genetics to genetic engineerings; 3) progress and perspectives of higher plant somatic cell genetics. 相似文献
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Chromosomal footprinting of transcriptionally active and inactive oocyte-type 5S RNA genes of Xenopus laevis 总被引:5,自引:2,他引:3
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The chromatin structure of the Xenopus oocyte-specific 5S rRNA genes was examined at high resolution in immature oocyte and somatic cell chromosomes by DNase I footprinting. On oocyte chromatin, where the genes are active, the cleavage preferences over the entire gene region showed a periodic pattern of sensitivity and were dramatically different from the patterns obtained with deproteinized DNA or somatic cell chromatin. Further, the normal binding site for TFIIIA over the internal promoter region was preferentially sensitive to cleavage, indicating that TFIIIA was not bound in the manner predicted by in vitro experiments. In somatic cell chromatin, the oocyte-type 5S genes displayed a cleavage pattern largely similar to deproteinized DNA suggesting the absence of positioned nucleosomes on these inactive genes, although the presence of uncharacterized repressor complexes could not be ruled out. These data are discussed in terms of potential forms of the chromatin structure and alternative mechanisms of oocyte-type gene activation. 相似文献
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Suh YH Kim MK Shin YK Kim SH Oh KI Gil M Kim MK Choi YL Jung KC Lee KM Lee IS Park SH 《Molecules and cells》2002,13(2):237-244
Hodgkin's disease (HD) is a lymphoid neoplasm characterized by a low frequency of malignant giant tumor cells, known as Hodgkin's and Reed-Sternberg (HRS) cells. Sequence analysis of the immunoglobulin heavy chain hypervariable region (IgH V) genes of HRS cells revealed multiple nucleotide substitutions, indicating somatic mutations, and suggested that HRS cells originate from germinal center B cells or their progeny. We previously reported that CD99-antisense transfected B cell lines led to the generation of cells with a HRS phenotype. Because it is considered that HRS cells in HD carry somatic mutations of the IgH genes, we assume that somatic mutation may take place in the IgH genes of HRS-like cells which do not express CD99. Here we report that CD99 downregulated BJAB cell line has several mutations in IgH V genes. The frequency of mutation was 5.2 x 10(-4) mut.bp(-1) out of total sequenced cell clones. On the contrary, control vector transfected BJAB cell line or CD99 downregulated IM9 cell line did not show any mutations on single strand conformational polymorphism (SSCP) and sequence analysis. We expect that the analysis of the mutation pattern of the CD99-deficient BJAB cell line might be the basis for the understanding of the molecular and cellular mechanism that regulate somatic mutation and B cell selection. 相似文献
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Antoine D. Rolland Aurélie Lardenois Anne-Sophie Goupil Jean-Jacques Lareyre Rémi Houlgatte Frédéric Chalmel Florence Le Gac 《PloS one》2013,8(1)
The capacity of testicular somatic cells to promote and sustain germ cell differentiation is largely regulated by sexual steroids and notably androgens. In fish species the importance of androgens is emphasized by their ability to induce sex reversal of the developing fries and to trigger spermatogenesis. Here we studied the influence of androgens on testicular gene expression in trout testis using microarrays. Following treatment of immature males with physiological doses of testosterone or 11-ketotestosterone, 418 genes that exhibit changes in expression were identified. Interestingly, the activity of testosterone appeared stronger than that of 11-ketotestosterone. Expression profiles of responsive genes throughout testis development and in isolated germ cells confirmed androgens to mainly affect gene expression in somatic cells. Furthermore, specific clusters of genes that exhibit regulation coincidently with changes in the natural circulating levels of androgens during the reproductive cycle were highlighted, reinforcing the physiological significance of these data. Among somatic genes, a phylogenetic footprinting study identified putative androgen response elements within the proximal promoter regions of 42 potential direct androgen target genes. Finally, androgens were also found to alter the germ line towards meiotic expression profiles, supporting the hypothesis of a role for the somatic responsive genes in driving germ cell fate. This study significantly increases our understanding of molecular pathways regulated by androgens in vertebrates. The highly cyclic testicular development in trout together with functions associated with regulated genes reveal potential mechanisms for androgen actions in tubule formation, steroid production, germ cell development and sperm secretion. 相似文献
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Collas P 《Cytotherapy》2007,9(3):236-244
Reprogramming of a differentiated cell into a cell capable of giving rise to many different cell types, a pluripotent cell, which in turn could repopulate or repair sick or damaged tissue, would present beneficial applications in regenerative medicine. Somatic cell nuclear transfer may offer this possibility, but technical hurdles and ethical frameworks currently prevent application of this technology in several countries. As a result, alternative strategies to reprogramming cell fate are being developed. This review briefly addresses somatic cell nuclear transfer and focuses on recent non-nuclear transfer-based approaches for reprogramming somatic cells and enhancing their differentiation potential. These include the fusion of somatic cells with embryonic stem cells, the treatment of somatic cells with extract of pluripotent cells and the retroviral transduction of somatic cells to overexpress pluripotency genes. 相似文献
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Burkitt's lymphoma is a malignancy of mature B cells expressing somatically mutated V region genes. 总被引:4,自引:0,他引:4
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U. Klein G. Klein B. Ehlin-Henriksson K. Rajewsky R. K¼ppers 《Molecular medicine (Cambridge, Mass.)》1995,1(5):495-505
BACKGROUND: The developmental stage from which stems the malignant B cell population in Burkitt's lymphoma (BL) is unclear. An approach to answering this question is provided by the sequence analysis of rear-ranged immunoglobulin (Ig) variable region (V) genes from BL for evidence of somatic mutations, together with a phenotypic characterization. As somatic hypermutation of Ig V region genes occurs in germinal center B cells, somatically mutated Ig genes are found in germinal center B cells and their descendents. MATERIALS AND METHODS: Rearranged V kappa region genes from 10 kappa-expressing sporadic and endemic BL-derived cell lines (9 IgM and 1 IgG positive) and three kappa-expressing endemic BL biopsy specimens were amplified by polymerase chain reaction and sequenced. In addition, VH region gene sequences from these cell lines were determined. RESULTS: All BL cell lines and the three biopsy specimens carried somatically mutated V region genes. The average mutation frequency of rearranged V kappa genes from eight BL cell lines established from sporadic BL was 1.8%. A higher frequency (6%) was found in five endemic cases (three biopsy specimens and two BL cell lines). CONCLUSIONS: The detection of somatic mutations in the rearranged V region genes suggests that both sporadic and endemic BL represent a B-cell malignancy originating from germinal center B cells or their descendants. Interestingly, the mutation frequency detected in sporadic BL is in a range similar to that characteristic for IgM-expressing B cells in the human peripheral blood and for mu chain-expressing germinal center B cells, whereas the mutation frequency found in endemic BL is significantly higher. 相似文献
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Four systems of cyclic somatic embryogenesis of Siberian ginseng (Eleutherococcus senticosus Maxim) were used to study the mechanism of embryonic cell cluster generation. The first, direct somatic embryo induction (DSEI), generates secondary embryos directly from the primary somatic embryos; the second, direct embryogenic cell cluster induction (DEC)), induces embryogenic cell clusters directly from somatic embryos in agar medium. Subsequently, we found that when DEC-derived somatic embryos are transferred to suspension culture or a bioreactor culture, only somatic embryos are induced, and embryogenic cell clusters cannot form. Therefore, these new lines were named DEC cultured by liquid medium (ECS) and DEC cultured by bioreactor (ECB), respectively. Transmission electron microscopy showed that DEC epidermal cells contained a variety of inclusions, distinct from other lines. A cDNA library of DEC was constructed, and 1,948 gene clusters were obtained and used as probes. RNA was prepared from somatic embryos from each of the four lines and hybridized to a microarray. In DEC, 7 genes were specifically upregulated compared with the other three lines, and 4 genes were downregulated. EsXTH1 and EsPLT1, which were among the genes upregulated in DEC, were cloned using the rapid amplification of cDNA ends (RACE). Real-time quantitative PCR showed EsXTH1 was more highly expressed in DEC than in other lines throughout the culture cycle, and EsPLT1 expression in DEC increased as culture duration increased, but remained at a low expression level in other lines. These results suggest that EsXTH1 and EsPLT1 may be the essential genes that play important roles during the induction of embryogenic cell clusters. 相似文献