| 1. |
- Englund, Ulrica, et al.
(författare)
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The use of a recombinant lentiviral vector for ex vivo gene transfer into the rat CNS
- 2000
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Ingår i: NeuroReport. - : Lippincott Williams & Wilkins. - 0959-4965 .- 1473-558X. ; 11:18, s. 3973-3977
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Tidskriftsartikel (refereegranskat)abstract
- A major obstacle in ex vivo gene transfer has been the loss of transgene expression soon after implantation of the grafted transduced cells. Recently, a lentiviral vector system has been developed which has proven to express high levels of transgenes in vivo after direct injection into the tissue. In this study, we have investigated the use of such a vector for ex vivo gene transfer to the brain. A number of neural cell types were found to be permissive to transduction by the lentiviral vector in vitro and a majority of them expressed the transgene after transplantation to the rat brain. Transgene expression was detected up to 8 weeks post-grafting. These findings suggest that recombinant lentiviral vectors may be used for further development of ex vivo gene therapy protocols to the CNS.
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| 2. |
- Fasching, Liana, et al.
(författare)
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TRIM28 Represses Transcription of Endogenous Retroviruses in Neural Progenitor Cells.
- 2015
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Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 10:1, s. 20-28
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Tidskriftsartikel (refereegranskat)abstract
- TRIM28 is a corepressor that mediates transcriptional silencing by establishing local heterochromatin. Here, we show that deletion of TRIM28 in neural progenitor cells (NPCs) results in high-level expression of two groups of endogenous retroviruses (ERVs): IAP1 and MMERVK10C. We find that NPCs use TRIM28-mediated histone modifications to dynamically regulate transcription and silencing of ERVs, which is in contrast to other somatic cell types using DNA methylation. We also show that derepression of ERVs influences transcriptional dynamics in NPCs through the activation of nearby genes and the expression of long noncoding RNAs. These findings demonstrate a unique dynamic transcriptional regulation of ERVs in NPCs. Our results warrant future studies on the role of ERVs in the healthy and diseased brain.
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| 3. |
- Flygare, Johan, et al.
(författare)
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Deficiency of ribosomal protein S19 in CD34+ cells generated by siRNA blocks erythroid development and mimics defects seen in Diamond-Blackfan anemia
- 2005
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 105:12, s. 4627-4634
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Tidskriftsartikel (refereegranskat)abstract
- Diamond-Blackfan anemia (DBA) is a congenital red cell aplasia in which 25% of the patients have a mutation in the ribosomal protein S19 (RPS19) gene. To study effects of RPS19 deficiency in hematopoiesis we transduced CD34+ umbilical cord blood (CB) and bone marrow (BM) cells with 3 lentiviral vectors expressing small interfering RNA (siRNA) against RPS19 and 1 scrambled control vector. All vectors also express green fluorescent protein (GFP). Transduction with the siRNA vectors reduced RPS19 mRNA levels to various degrees, which resulted in erythroid defects, correlating to the degree of RPS19 down-regulation, and was rescued by expression of an siRNA-resistant RPS19 transcript. Erythroid colony formation capacity conjointly decreased with RPS19 levels in CD34+ CB and BM cells. In liquid culture supporting erythroid differentiation, RPS19-silenced as well as DBA patient CD34+ cells exhibited reduced proliferative capacity and impaired erythroid differentiation resulting in fewer erythroid colony-forming units (CFU-Es). When assaying myeloid development, a less pronounced influence on proliferation was seen. This study shows for the first time that RPS19 silencing decreases the proliferative capacity of hematopoietic progenitors and leads to a defect in erythroid development.
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| 4. |
- Johansson, Pia A, et al.
(författare)
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A cis-acting structural variation at the ZNF558 locus controls a gene regulatory network in human brain development
- 2022
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Ingår i: Cell Stem Cell. - : Elsevier BV. - 1934-5909 .- 1875-9777. ; 29:1, s. 8-69
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Tidskriftsartikel (refereegranskat)abstract
- The human forebrain has expanded in size and complexity compared to chimpanzees despite limited changes in protein-coding genes, suggesting that gene expression regulation is an important driver of brain evolution. Here, we identify a KRAB-ZFP transcription factor, ZNF558, that is expressed in human but not chimpanzee forebrain neural progenitor cells. ZNF558 evolved as a suppressor of LINE-1 transposons but has been co-opted to regulate a single target, the mitophagy gene SPATA18. ZNF558 plays a role in mitochondrial homeostasis, and loss-of-function experiments in cerebral organoids suggests that ZNF558 influences developmental timing during early human brain development. Expression of ZNF558 is controlled by the size of a variable number tandem repeat that is longer in chimpanzees compared to humans, and variable in the human population. Thus, this work provides mechanistic insight into how a cis-acting structural variation establishes a regulatory network that affects human brain evolution.
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| 5. |
- Lundberg, Cecilia, et al.
(författare)
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Differentiation of the RN33B Cell Line into Forebrain Projection Neurons after Transplantation into the Neonatal Rat Brain.
- 2002
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886 .- 1090-2430. ; 175:2, s. 370-387
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Tidskriftsartikel (refereegranskat)abstract
- The rat neural cell line RN33B has a remarkable ability to undergo region-specific neuronal differentiation after transplantation into the CNS. To further study its neurogenic properties in vivo, we used a recombinant lentiviral vector to genetically label the cells with the Green Fluorescent Protein (GFP) gene before implantation into the striatum/cortex, hippocampus, or mesencephalon of newborn rats. Three weeks after implantation, about 1-2% of the GFP-expressing cells had developed morphologies typical of neurons, astrocytes, or oligodendrocytes, the rest remained as either immature or undifferentiated nestin-positive cells. At 15-17 weeks postgrafting, the immature cells had disappeared in most graft recipients and only cells with neuronal or glial morphologies remained in similar numbers as at 3 weeks. The GFP distributed throughout the expressing cells, revealing fine morphological details, including dendrites with spines and extensive axonal projections. In all forebrain regions, the grafted cells differentiated into neurons with morphologies characteristic for each site, including large numbers of pyramidal-like cells in the cortex and the hippocampus, giving rise to dense projections to normal cortical target regions and to the contralateral hippocampus, respectively. In lower numbers, it was also possible to identify GFP-positive granulelike cells in the hippocampus, as well as densely spiny neurons in the striatum. In the mesencephalon by contrast, cells with astrocytic features predominated. The ability of the grafted RN33B cells to undergo region-specific differentiation into highly specialized types of forebrain projection neurons and establish connections with appropriate targets suggests that cues present in the microenvironment of the neonatal rat brain can effectively guide the development of immature progenitors, also in the absence of ongoing neurogenesis. (c) 2002 Elsevier Science (USA).
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| 6. |
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| 7. |
- Rowe, Helen M., et al.
(författare)
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KAP1 controls endogenous retroviruses in embryonic stem cells
- 2010
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 463, s. 40-237
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Tidskriftsartikel (refereegranskat)abstract
- More than forty per cent of the mammalian genome is derived from retroelements, of which about one-quarter are endogenous retroviruses (ERVs). Some are still active, notably in mice the highly polymorphic early transposon (ETn)/MusD and intracisternal A-type particles (IAP). ERVs are transcriptionally silenced during early embryogenesis by histone and DNA methylation (and reviewed in ref. 7), although the initiators of this process, which is essential to protect genome integrity, remain largely unknown. KAP1 (KRAB-associated protein 1, also known as tripartite motif-containing protein 28, TRIM28) represses genes by recruiting the histone methyltransferase SETDB1, heterochromatin protein 1 (HP1) and the NuRD histone deacetylase complex, but few of its physiological targets are known. Two lines of evidence suggest that KAP1-mediated repression could contribute to the control of ERVs: first, KAP1 can trigger permanent gene silencing during early embryogenesis, and second, a KAP1 complex silences the retrovirus murine leukaemia virus in embryonic cells. Consistent with this hypothesis, here we show that KAP1 deletion leads to a marked upregulation of a range of ERVs, in particular IAP elements, in mouse embryonic stem (ES) cells and in early embryos. We further demonstrate that KAP1 acts synergistically with DNA methylation to silence IAP elements, and that it is enriched at the 5' untranslated region (5'UTR) of IAP genomes, where KAP1 deletion leads to the loss of histone 3 lysine 9 trimethylation (H3K9me3), a hallmark of KAP1-mediated repression. Correspondingly, IAP 5'UTR sequences can impose in cis KAP1-dependent repression on a heterologous promoter in ES cells. Our results establish that KAP1 controls endogenous retroelements during early embryonic development.
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| 8. |
- Rowe, Helen M., et al.
(författare)
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TRIM28 repression of retrotransposon-based enhancers is necessary to preserve transcriptional dynamics in embryonic stem cells
- 2013
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory. - 1549-5469 .- 1088-9051. ; 23:3, s. 452-461
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Tidskriftsartikel (refereegranskat)abstract
- TRIM28 is critical for the silencing of endogenous retroviruses (ERVs) in embryonic stem (ES) cells. Here, we reveal that an essential impact of this process is the protection of cellular gene expression in early embryos from perturbation by cis-acting activators contained within these retroelements. In TRIM28-depleted ES cells, repressive chromatin marks at ERVs are replaced by histone modifications typical of active enhancers, stimulating transcription of nearby cellular genes, notably those harboring bivalent promoters. Correspondingly, ERV-derived sequences can repress or enhance expression from an adjacent promoter in transgenic embryos depending on their TRIM28 sensitivity in ES cells. TRIM28-mediated control of ERVs is therefore crucial not just to prevent retrotransposition, but more broadly to safeguard the transcriptional dynamics of early embryos.
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| 9. |
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| 10. |
- Åkerblom, Malin, et al.
(författare)
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MicroRNA-124 Is a Subventricular Zone Neuronal Fate Determinant.
- 2012
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Ingår i: The Journal of Neuroscience : the official journal of the Society for Neuroscience. - 1529-2401. ; 32:26, s. 8879-8889
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Tidskriftsartikel (refereegranskat)abstract
- New neurons are continuously generated from neural stem cells with astrocyte properties, which reside in close proximity to the ventricle in the postnatal and adult brain. In this study we found that microRNA-124 (miR-124) dictates postnatal neurogenesis in the mouse subventricular zone. Using a transgenic reporter mouse we show that miR-124 expression is initiated in the rapid amplifying progenitors and remains expressed in the resulting neurons. When we stably inhibited miR-124 in vivo, neurogenesis was blocked, leading to the appearance of ectopic cells with astrocyte characteristics in the olfactory bulb. Conversely, when we overexpressed miR-124, neural stem cells were not maintained in the subventricular zone and neurogenesis was lost. In summary, our results demonstrate that miR-124 is a neuronal fate determinant in the subventricular zone.
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