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At least 955 records · Page 53Linked to original sources
PubMed1993

Rapid re-expression of CD45RC on rat CD4 T cells in vitro correlates with a change in function.

Rat CD4+ T cells are divided phenotypically by the anti-CD45RC monoclonal antibody OX22 into subsets with contrasting functions. Stimulation of T cells in vitro is known to induce a change in isoform from CD45RC+ to CD45RC-. We have investigated the in vitro conditions which promote a switch in isoform in the opposite direction. We observed that a majority of CD45RC- CD4 T cells (> 90%) spontaneously re-expressed CD45RC during the first 1-3 days of culture in both the presence and absence of alloantigen. The T cells remained CD45RC+ when cultured for 7 days in serum-free growth medium. However, alloantigen-activated lymphocytes, expressing the interleukin-2 receptor (IL-2R), downregulated CD45RC by day 4 and remained CD45RC- during the course of the experiment. Using mixtures of allotype-marked CD45RC+ and CD45RC- T cells, it was demonstrated that each subset showed comparable survival, IL-2R expression and time courses of activation in response to alloantigen. The repertoire of neither subset was, therefore, deficient in terms of allorecognition. The rapid re-expression of CD45RC in culture was accompanied by a change in function: CD45RC+ "converts", obtained by overnight culture of CD45RC- T cells, induced significantly higher graft-versus-host responses. Thus, the transition in culture from CD45RC- to CD45RC+ reflects a major functional reprogramming of the cell and not a trivial modulation of a surface antigen.

Animals↗
PubMed2026

Functional and Proteomic Profiles of CD3(+) Plasma-Derived Small Extracellular Vesicles Differentiate Cancer Patients From Healthy Donors.

Small extracellular vesicles (sEV) released by T cells play a key role in immune regulation. Immune capture with anti-CD3 antibodies was used to isolate and study T cell-derived CD3(+)sEV from the plasma of patients with melanoma (MPs) or healthy donors (HDs). Functional responses induced in recipient target cells by CD3(+)sEV of MPs differed from responses induced by CD3(+)sEV of HDs. Approximating functions mediated by melanoma cell-derived sEV (MTEX), CD3(+)sEV of MPs reduced metabolic activity and proliferation of T cells while promoting activity in Mel526 cell targets. Proteomics profiling confirmed functional differences between CD3(+)sEV of MPs and HDs. Of 294 sEV-specific proteins identified in CD3(+)sEV, 226 were detected in the parent T cell proteome, confirming that the CD3(+)sEV proteome mimics that of the parent T lymphocytes. Among them were 66 differentially expressed proteins (DEPs) that differentiated vesicles from MPs and HDs. These DEPs were associated with processes linked to cancer-related functions. DEPs upregulated in CD3(+)sEV of MPs were associated with RHO-GTPase, cytokine, and MAPK signaling pathways. Thus, T cells of MPs were reprogrammed by MTEX to produce CD3(+)sEV that functionally resembled MTEX, partly recapitulated features of the tumor proteome, and differed from CD3(+)sEV of HDs. In cancer, the TEX-rewired T cells produce CD3(+)sEV that potentially could serve as a liquid biopsy of patients' T cells.

Humans↗
PubMed2005

Widespread disruption of genomic imprinting in adult interspecies mouse (Mus) hybrids.

Mammalian interspecies hybrids exhibit parent-of-origin effects in that offspring of reciprocal matings, even though genetically identical, frequently exhibit opposite phenotypes, especially in growth. This was also observed in hybridization with the genus Mus. These parent-of-origin effects suggested that imbalance in the expression of imprinted genes, which are expressed differentially, depending on their transmission through the maternal or paternal germline, and/or differential loss-of-imprinting (LOI) could underlie these opposite growth phenotypes in reciprocal mammalian hybrids. Here we report that tissue-specific LOI occurs in adult Mus hybrids. Contrary to expectations, LOI patterns were not consistent with a direct influence of altered expression levels of imprinted genes on growth. Bisulfite sequencing revealed that reactivation of maternal alleles of Peg3 and Snrpn in specific tissues was accompanied by partial demethylation at their potential imprinting control regions. We propose that abnormal reprogramming after fertilization and during preimplantation development is in part responsible for hybrid dysgenesis, for which a strong epigenetic basis has been demonstrated.

Animals↗
PubMed2002

RANTES stimulates inflammatory cascades and receptor modulation in murine astrocytes.

Cultured mouse astrocytes respond to the CC chemokine RANTES by production of chemokine and cytokine transcripts. Stimulation of astrocytes with 1 nM RANTES or 3-10 nM of the structurally related chemokines (eotaxin, macrophage inflammatory protein-1alpha and -beta [MIP-1alpha, MIP-1beta]) induced transcripts for KC, monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-alpha), MIP-1alpha, MIP-2, and RANTES in a chemokine and cell-specific fashion. Synthesis of chemokine (KC and MCP-1) and cytokine (TNF-alpha) proteins was also demonstrated. RANTES-mediated chemokine synthesis was specifically inhibited by pertussis toxin, indicating that G-protein-coupled chemokine receptors participated in astrocyte signaling. Astrocytes expressed CCR1 and CCR5 (the redundant RANTES receptors). Astrocytes derived from mice with targeted mutations of either CCR1 or CCR5 respond after RANTES stimulation, suggesting multiple chemokine receptors may separately mediate RANTES responsiveness in astrocytes. Preliminary data suggest activation of the MAP kinase pathway is also critical for RANTES-mediated signaling in astrocytes. Treatment with RANTES specifically modulated astrocyte receptors upregulating intercellular adhesion molecule 1 (ICAM-1) and downregulating CX3CR1 expression. Thus, after chemokine treatment, astrocytes release proinflammatory mediators and reprogram their surface molecules. The combined effects of RANTES may serve to amplify inflammatory responses within the central nervous system.

Animals↗
PubMed2004

Translocation of protein kinase C-betaII in astrocytes requires organized actin cytoskeleton and is not accompanied by synchronous RACK1 relocation.

Protein kinase C (PKC)-betaII is the most abundant PKC isoform in astrocytes. Upon activation, this isoform of PKC translocates from the cytosol to the plasma membrane (PM). In this study, we investigated in astrocytes the modality of PKC-betaII translocation as far as the participation of the receptor for activated C kinase-1 (RACK1) and the requirement for intact cytoskeleton in the process. In astrocytes, Western blots and immunocytochemistry coupled to confocal microscopic quantitative analysis showed that after 5 min of phorbol-12-myristate-13-acetate (PMA) exposure, native PKC-betaII, but not PKC-betaI, is relocated efficiently from the cytosol to the PM. Translocation of PKC-betaII was not associated with synchronous RACK1 relocation. Furthermore, the quantity of PM-associated PKC-betaII that co-immunoprecipitated with PM-bound RACK1 increased following PMA exposure, indicating a post activation binding of the two proteins in the PM. Because RACK1 and PKC-betaII relocation seemed not to be synchronous, we hypothesized that an intermediate interaction with the cytoskeleton was taking place. In fact, we were able to show that pharmacological disruption of actin-based cytoskeleton greatly deranged PKC-betaII translocation to the PM. The requirement for intact actin cytoskeleton was specific, because depolymerization of tubulin had no effect on the ability of the kinase to translocate to the PM. These results indicate that in astrocytes, RACK1 and PKC-betaII synchronous relocation is not essential for relocation of PKC-betaII to the PM. In addition, we show for the first time that the integrity of the actin cytoskeleton plays a specific role in PKC-betaII movements in these cells. We hypothesize that in glial cells, rapidly occurring changes of actin cytoskeleton arrangement may be involved in the fast reprogramming of PKC targeting to specific PM location to phosphorylate substrates in different cellular locations.

Actin Cytoskeleton↗
PubMed2005

IL-1-regulated responses in astrocytes: relevance to injury and recovery.

In the central nervous system (CNS), the cellular processes of astrocytes make intimate contact with essentially all areas of the brain. They have also been shown to be functionally coupled to neurons, oligodendrocytes, and other astrocytes via both contact-dependent and non-contact-dependent pathways. These observations have led to the suggestion that a major function of astrocytes in the CNS is to maintain the homeostatic environment, thus promoting the proper functioning of the neuronal network. Inflammation in the CNS disrupts this process either transiently or permanently and, as such, is thought to be tightly regulated by both astrocytes and microglia. The remarkable role that single cytokines, such as TNF and IL-1, may play in this process has now been well accepted, but the extent of the reprogramming of the transcriptional machinery initiated by these factors remains to be fully appreciated. With the advent of microarray technology, a more comprehensive analysis of this process is now available. In this report we review data obtained with this technology to provide an overview of the extent of changes induced in astrocytes by the cytokine IL-1.

Animals↗
PubMed2004

Plasticity in the adult rat pancreas: transdifferentiation of exocrine to hepatocyte-like cells in primary culture.

Under certain experimental conditions, hepatocytes can arise in the pancreas. It has been suggested that the pancreas retains a source of hepatocyte progenitor cells. However, such cells have not been yet identified in the adult pancreas. We describe here the transdifferentiation of primary rat pancreatic exocrine cells into hepatocyte-like cells during 5 days of tissue culture in the presence of dexamethasone (DX). Using reverse-transcription polymerase chain reaction and immunocytochemistry, it was observed that DX treatment induced albumin RNA and protein expression in the cells. Coexpression of albumin and amylase, and the absence of cell proliferation, demonstrated a direct transdifferentiation of acinar cells to hepatocytic cells. CCAAT enhancer-binding protein-ss protein, a liver-enriched transcription factor that is considered to be the master switch in pancreatohepatic transdifferentiation, and alpha-fetoprotein were markedly upregulated in the cells after treatment with DX. We compared transcriptional profiles of freshly isolated exocrine cells and DX-treated cells using oligonucleotide microarrays and found that multiple liver-specific genes are induced along with albumin, and that certain pancreatic genes are downregulated in the DX-treated cells. In conclusion, these observations support the notion of plasticity in the adult pancreas and that exocrine cells can be reprogrammed to transdifferentiate into other cell types such as hepatocytes.

Age Factors↗
PubMed2006

Host cell responses induced by hepatitis C virus binding.

Initiation of hepatitis C virus (HCV) infection is mediated by docking of the viral envelope to the hepatocyte cell surface membrane followed by entry of the virus into the host cell. Aiming to elucidate the impact of this interaction on host cell biology, we performed a genomic analysis of the host cell response following binding of HCV to cell surface proteins. As ligands for HCV-host cell surface interaction, we used recombinant envelope glycoproteins and HCV-like particles (HCV-LPs) recently shown to bind or enter hepatocytes and human hepatoma cells. Gene expression profiling of HepG2 hepatoma cells following binding of E1/E2, HCV-LPs, and liver tissue samples from HCV-infected individuals was performed using a 7.5-kd human cDNA microarray. Cellular binding of HCV-LPs to hepatoma cells resulted in differential expression of 565 out of 7,419 host cell genes. Examination of transcriptional changes revealed a broad and complex transcriptional program induced by ligand binding to target cells. Expression of several genes important for innate immune responses and lipid metabolism was significantly modulated by ligand-cell surface interaction. To assess the functional relevance and biological significance of these findings for viral infection in vivo, transcriptional changes were compared with gene expression profiles in liver tissue samples from HCV-infected patients or controls. Side-by-side analysis revealed that the expression of 27 genes was similarly altered following HCV-LP binding in hepatoma cells and viral infection in vivo. In conclusion, HCV binding results in a cascade of intracellular signals modulating target gene expression and contributing to host cell responses in vivo. Reprogramming of cellular gene expression induced by HCV-cell surface interaction may be part of the viral strategy to condition viral entry and replication and escape from innate host cell responses.

Antigens, Viral↗
PubMed1990

Expression of a homeobox gene in the chick wing bud following application of retinoic acid and grafts of polarizing region tissue.

Homeobox gene XlHbox 1 is expressed in a mesodermal gradient in vertebrate forelimbs with maximal expression anteriorly and proximally and may encode positional values. In chick wing buds, anterior cells can be reprogrammed to form posterior structures by grafts of polarizing region tissue and by beads soaked in retinoic acid (RA), which is a good candidate for an endogenous morphogen. Applications of RA anteriorly or at the bud apex, treatments which produce duplicated digits or truncations respectively, substantially increase the extent of mesodermal XlHbox 1 expression. Polarizing region grafts that also produce additional digits lead to a moderate increase. The effects of RA application and the behaviour of transplanted tissue show that only anterior cells are competent to express XlHbox 1 and that expression is cell autonomous. Ectodermal expression in wing buds is enhanced by RA but not by polarizing region grafts and ectoderm/mesoderm recombinations show that the mesoderm is irreversibly affected. The changes in mesodermal expression do not fit the predictions of the simple model that XlHbox 1 encodes anterior positional values but are correlated with a series of novel malformations of the shoulder girdle which, in normal wing buds, is derived from cells expressing XlHbox 1.

Animals↗
PubMed2003

Copernican stem cells: regulatory constellations in adult hippocampal neurogenesis.

In the adult, neurogenesis occurs where constellations of signaling molecules are correctly orchestrated and where competent cells are present to interpret these signals. As the instruments used to observe adult neurogenesis become more sophisticated, the concept of a discrete competent "stem cell" has become less concrete. Neural progenitor cells once thought committed to a single lineage can be influenced to become multipotent and somatic tissues appear to yield cells capable of tremendous peripheral and central lineage potential. The variety of cell types that appear competent to generate neurons suggests that the "Hilios" of adult neurogenesis may not necessarily be a single cellular entity but rather the sum of signals that dictate, "Make a new neuron here." These signals may not be limited to the recruitment of preexisting neural stem cells but may also, in some subtle way, reprogram local precursors to create "stem-like cells," where needed.

Animals↗
PubMed2005

Spatio-temporal dynamics at rDNA foci: global switching between DNA replication and transcription.

We have investigated the in situ organization of ribosomal gene (rDNA) transcription and replication in HeLa cells. Fluorescence in situ hybridization (FISH) revealed numerous rDNA foci in the nucleolus. Each rDNA focus corresponds to a higher order chromatin domain containing multiple ribosomal genes. Multi-channel labeling experiments indicated that, in the majority of cells, all the rDNA foci were active in transcription as demonstrated by co-localization with signals to transcription and fibrillarin, a protein involved in ribosomal RNA processing. In some cells, however, a small portion of the rDNA foci did not overlap with signals to transcription and fibrillarin. Labeling for DNA replication revealed that those rDNA foci inactive in transcription were restricted to the S-phase of the cell cycle and were replicated predominantly from mid to late S-phase. Electron microscopic analysis localized the nucleolar transcription, replication, and fibrillarin signals to the dense fibrillar components of the nucleolus and at the borders of the fibrillar centers. We propose that the rDNA foci are the functional units for coordinating replication and transcription of the rRNA genes in space and time. This involves a global switching mechanism, active from mid to late S-phase, for turning off transcription and turning on replication at individual rDNA foci. Once all the rRNA genes at individual foci are replicated, these higher order chromatin domains are reprogrammed for transcription.

DNA Replication↗
PubMed2007

The commonality of plasticity underlying multipotent tumor cells and embryonic stem cells.

Aggressive cancer cells and pluripotent stem cells converge in their capacity for self-renewal, proliferation and plasticity. Recent studies have capitalized on these similarities by demonstrating that tumors arise from specific cancer stem cell populations that, in a manner reminiscent of normal stem cells, are able to both self-renew and give rise to a heterogeneous tumor population. This stem cell like function of aggressive cancer cells is likely attributable to the ectopic expression of embryonic factors such as Nodal and Cancer Testis Specific Antigens (CTAs), which maintain a functional plasticity by promoting pluripotency and immortality. During development, the expression of these embryonic factors is tightly regulated by a dynamic array of mediators, including the spatial and temporal expression of inhibitors such as Lefty, and the epigenetic modulation of the genome. In aggressive cancer cells, particularly melanoma, this balance of regulatory mediators is disrupted, leading to the aberrant expression of pluripotency-associated genes. By exposing aggressive cancer cells to embryonic microenvironments, this balance of regulatory mediators is restored, thereby reprogramming tumor cells to a more benign phenotype. These stem cell-derived mediators, as well as the genes they regulate, provide therapeutic targets designed to specifically differentiate and eradicate aggressive cancers.

Cell Lineage↗
PubMed2006

The epigenetic network regulating muscle development and regeneration.

This review focuses on our current knowledge of the epigenetic changes regulating gene expression at the chromatin and DNA level, independently on the primary DNA sequence, to reprogram the nuclei of muscle precursors during developmental myogenesis and muscle regeneration. These epigenetic marks provide the blueprint by which the extra-cellular cues are interpreted at the nuclear level by the transcription machinery to select the repertoire of tissue-specific genes to be expressed. The reversibility of some of these changes necessarily reflects the dynamic nature of skeletal myogenesis, which entails the progression through two antagonistic processes--proliferation and differentiation. Other epigenetic modifications are instead associated to events conventionally considered as irreversible--e.g. maintenance of lineage commitment and terminal differentiation. However, recent results support the possibility that these events can be reversed, at least upon certain experimental conditions, thereby revealing a dynamic nature of many of the epigenetic modifications underlying skeletal myogenesis. The elucidation of the epigenetic network that regulates transcription during developmental myogenesis and muscle regeneration might provide the information instrumental to devise pharmacological interventions toward selective manipulation of gene expression to promote regeneration of skeletal muscles and possibly other tissue.

Animals↗
PubMed2026

Bovine Colostrum-Derived Extracellular Vesicles Impair Cancer Cell Proliferation Through Transcriptional Dysregulation.

Milk-derived extracellular vesicles (EVs) are a promising source of molecules with therapeutic potential. Bovine colostrum is particularly enriched in EVs, which carry cargo of proteins involved in immune regulation, development and cellular signalling. Some studies have explored their role as bioactive anti-cancer agents, however, their mechanistic effects remain underexplored. Here, we show that colostrum-derived EVs (Col-EVs) exert anti-proliferative effects in gastrointestinal cancer models, including cell lines and patient-derived organoids, which is independent of apoptosis induction. Using a multi-modal approach combining proteomics, imaging and functional assays, we demonstrate that Col-EVs induce a reversible growth-arrest state, characterized by widespread transcriptional and RNA-processing dysregulation, chromatin compaction, nuclear reorganization and cytoskeletal remodelling. Proteomic analyses reveal that Col-EV treatment disrupts key components of the transcriptional machinery and cell cycle regulatory pathways, effects that are reversible upon EV withdrawal and can be rescued pharmacologically using an EZH2 inhibitor. Col-EVs enhance the sensitivity of cancer cells as well to DNA-targeting chemotherapies such as 5-fluorouracil, indicating their potential as modulatory adjuvants rather than cytotoxic agents. Overall, our findings reveal that Col-EVs can reversibly suppress cancer cell proliferation by reprogramming transcriptional and nuclear architecture, offering a natural, biocompatible strategy for modulating tumour growth and sensitizing cancer cells to conventional therapies.

Extracellular Vesicles↗
PubMed2002

Factors affecting the efficiency of somatic cell nuclear transplantation in the fish embryo.

Procedures to improve somatic cell nuclear transplantation in fish were evaluated. We reported effects of nonirradiated recipient eggs, inactivated recipient eggs, different combinations between recipient eggs and donor cells, duration of serum starvation, generation number, and passage number of donor cells on developmental rates of nuclear transplant (NT) embryos. Exposure to 25,000 R of gamma-rays inactivated recipient eggs. Single nucleus of cultured, synchronized somatic cell from gynogenetic bighead carp (Aristichthys nobilis) was transplanted into nonirradiated or genetically inactivated unfertilized egg of gibel carp (Carassius auratus gibelio). There was no significant difference in developmental rate between nonirradiated and inactivated recipient eggs (27.27% vs. 25.71%, respectively). Chromosome count showed that 70.59% of NT embryos contained 48 chromosomes. It showed that most NT embryos came from donor nuclei of bighead carp, which was supported by microsatellite analysis of NT embryos. But 23.53% of NT embryos contained more than 48 chromosomes. It was presumed that those superfluous chromosomes came from nonirradiated recipient eggs. Besides, 5.88% of NT embryos were chimeras. Eggs of blunt-snout bream (Megalobrama amblycephala) and gibel carp were better recipient eggs than those of loach (Misgurnus anguillicaudatus) (25% and 18.03% vs. 8.43%). Among different duration of serum starvation, developmental rate of NT embryos from somatic nuclei of three-day serum starvation was the highest, reaching 25.71% compared to 14.14% (control), 20% (five-day), and 21.95% (seven-day). Cultured donor cells of less passage facilitated reprogramming of NT embryos than those of more passage. Recloning might improve the developmental rate of NT embryos from the differentiated donor nuclei. Developmental rate of fourth generation was the highest (54.83%) and the lowest for first generation (14.14%) compared to second generation (38.96%) and third generation (53.01%).

Animals↗
PubMed1982

Effect of antimetabolites on programming of inner cells of the mouse blastocyst.

When early blastocysts are subjected to immunosurgery, the resulting inner cell masses (ICMs) regenerate trophoblast cells. In contrast, ICMs from later blastocysts produce endoderm cells. We have found that if embryos are treated with cycloheximide during the transition from the early to late blastocyst stages, subsequently isolated ICMs give rise to trophoblast-like giant cells. These cells do not, however, exhibit detectable levels of delta 5, 3 beta-hydroxysteroid dehydrogenase, an enzyme normally found in primary trophoblast cells. Neither Colcemid nor alpha-amanitin affects the conversion of the ICM program in the same way as cycloheximide, although alpha-amanitin added at later stages interferes with the formation of a cohesive endoderm layer around the isolated ICM. We propose that the reprogramming of ICM cells involves at least two events: one terminates the giant cell program and the other, occurring later in development, promotes endoderm formation.

3-Hydroxysteroid Dehydrogenases↗
PubMed2005

A novel binary adenovirus-based dual-regulated expression system for independent transcription control of two different transgenes.

BACKGROUND: Stringent multitransgene control is a prerequisite for future gene-therapy and tissue-engineering scenarios and requires constant improvements in design to achieve optimal conditional transcription profiles. METHODS: We have pioneered a variety of recombinant adenoviruses which (i) enable streptogramin-responsive transgene transduction in a compact autoregulated one-virus format, (ii) manage independent streptogramin- and tetracycline-responsive control of two different transgenes from a single divergent expression unit, and (iii) control sense and antisense expression of the human cyclin-dependent kinase inhibitor p27(Kip1) to engineer conditional positive (enforced S-phase entry, p27(Kip1)-antisense expression) or negative (G1-phase-specific growth arrest, p27(Kip1)-sense expression) growth control in mammalian cell lines and human primary cells. RESULTS: The transgene control performance of all adenoviral expression configurations has been rigorously optimized for tight, balanced and maximum expression levels and was validated for intracellular as well as for secreted product in a variety of biotechnologically relevant cell lines (Chinese hamster ovary cells [CHO-K1], baby hamster kidney cells [BHK-21]) as well as in human cell lines (human fibrosarcoma cells [HT-1080]) and primary cells (human aortic fibroblasts [HAFs]). CONCLUSIONS: We believe that multiregulated multigene-controlled adenoviruses are important assets for successful therapeutic reprogramming of mammalian cells in clinically relevant scenarios.

Adenoviridae↗
PubMed2005

In vivo transduction of HIV-1-derived lentiviral particles engineered for macrolide-adjustable transgene expression.

BACKGROUND: The molecular merger of latest-generation transduction technologies with advanced transgene control modalities may foster decisive advances in therapeutic reprogramming of somatic cell phenotypes. METHODS: We have engineered self-inactivating HIV-1-based lentiviral expression vectors for reversible macrolide-adjustable transgene expression. RESULTS: Lentiviral particles engineered for macrolide-responsive human vascular endothelial growth factor 121 (VEGF121) expression compared favourably with isogenic streptogramin- and tetracycline-responsive configurations and showed excellent growth-factor fine-tuning following transduction into a variety of mammalian cell lines and different human primary cells. Chicken embryos transduced for macrolide-controlled VEGF121 production exhibited dose-dependent neovascularization and exemplified lentivector-delivered transgene transcription fine-tuning in vivo. CONCLUSIONS: Macrolide-adjustable lentivectors enable robust and precise in vitro and in vivo transgene fine-tuning which may give future gene therapy trials a new impetus.

Animals↗