| 1. |
- Brattås, Per Ludvik, et al.
(författare)
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TRIM28 Controls a Gene Regulatory Network Based on Endogenous Retroviruses in Human Neural Progenitor Cells
- 2017
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Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 18:1, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Endogenous retroviruses (ERVs), which make up 8% of the human genome, have been proposed to participate in the control of gene regulatory networks. In this study, we find a region- and developmental stage-specific expression pattern of ERVs in the developing human brain, which is linked to a transcriptional network based on ERVs. We demonstrate that almost 10,000, primarily primate-specific, ERVs act as docking platforms for the co-repressor protein TRIM28 in human neural progenitor cells, which results in the establishment of local heterochromatin. Thereby, TRIM28 represses ERVs and consequently regulates the expression of neighboring genes. These results uncover a gene regulatory network based on ERVs that participates in control of gene expression of protein-coding transcripts important for brain development.
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| 2. |
- Kvarnung, Malin, et al.
(författare)
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Ataxia in Patients With Bi-Allelic NFASC Mutations and Absence of Full-Length NF186
- 2019
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Ingår i: Frontiers in Genetics. - : Frontiers Media SA. - 1664-8021. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- The etiology of hereditary ataxia syndromes is heterogeneous, and the mechanisms underlying these disorders are often unknown. Here, we utilized exome sequencing in two siblings with progressive ataxia and muscular weakness and identified a novel homozygous splice mutation (c.3020-1G > A) in neurofascin (NFASC). In RNA extracted from fibroblasts, we showed that the mutation resulted in inframe skipping of exon 26, with a deprived expression of the full-length transcript that corresponds to NFASC isoform NF186. To further investigate the disease mechanisms, we reprogrammed fibroblasts from one affected sibling to induced pluripotent stem cells, directed them to neuroepithelial stem cells and finally differentiated to neurons. In early neurogenesis, differentiating cells with selective depletion of the NF186 isoform showed significantly reduced neurite outgrowth as well as fewer emerging neurites. Furthermore, whole-cell patch-clamp recordings of patient-derived neuronal cells revealed a lower threshold for openings, indicating altered Na+ channel kinetics, suggesting a lower threshold for openings as compared to neuronal cells without the NFASC mutation. Taken together, our results suggest that loss of the full-length NFASC isoform NF186 causes perturbed neurogenesis and impaired neuronal biophysical properties resulting in a novel early-onset autosomal recessive ataxia syndrome.
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| 3. |
- Schuy, Jakob, et al.
(författare)
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Partial Monosomy 21 Mirrors Gene Expression of Trisomy 21 in a Patient-Derived Neuroepithelial Stem Cell Model
- 2022
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Ingår i: Frontiers in Genetics. - : Frontiers Media SA. - 1664-8021. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Induced pluripotent stem cells (iPSCs) from patients are an attractive disease model to study tissues with poor accessibility such as the brain. Using this approach, we and others have shown that trisomy 21 results in genome-wide transcriptional dysregulations. The effects of loss of genes on chromosome 21 is much less characterized. Here, we use patient-derived neural cells from an individual with neurodevelopmental delay and a ring chromosome 21 with two deletions spanning 3.8 Mb at the terminal end of 21q22.3, containing 60 protein-coding genes. To investigate the molecular perturbations of the partial monosomy on neural cells, we established patient-derived iPSCs from fibroblasts retaining the ring chromosome 21, and we then induced iPSCs into neuroepithelial stem cells. RNA-Seq analysis of NESCs with the ring chromosome revealed downregulation of 18 genes within the deleted region together with global transcriptomic dysregulations when compared to euploid NESCs. Since the deletions on chromosome 21 represent a genetic “contrary” to trisomy of the corresponding region, we further compared the dysregulated transcriptomic profile in with that of two NESC lines with trisomy 21. The analysis revealed opposed expression changes for 23 genes on chromosome 21 as well as 149 non-chromosome 21 genes. Taken together, our results bring insights into the effects on the global and chromosome 21 specific gene expression from a partial monosomy of chromosome 21qter during early neuronal differentiation.
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| 4. |
- Shahsavani, Mansoureh
(författare)
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Cellular models of human brain disorders from skin to brain
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Studying human brain development and disorders is very challenging. In the absence of comparable model organisms, human-related models, and limitations to obtain live cells from the human brain, induced Pluripotent Stem Cell (iPSC) technology, in particular, provided a unique tool to study the disease mechanisms and investigate potential treatments. The main goal of this thesis was to study neurological disorders and explore novel mechanisms underlying the diseases. We have generated and characterised patient and healthy control iPSCs using Sendai virus as a safe non-integrating method to keep the host genome intact. We have then shown an example of a standardised culture condition by using recombinant spider silk coating for iPSCs and Embryonic Stem Cells (ESCs) cultivation in 2D and 3D formats. Healthy Pluripotent Stem Cell lines cultured on recombinant spider silk displayed the typical stem cell morphology with the expression of pluripotent stem cell markers. Considering the xeno-free culture coating and compatibility with the host immune system, the spider silk, can provide an optimal routine culture system for pluripotent stem cells and future iPSC based therapies. Patient and healthy iPSCs were neurally induced to generate intermediate, expandable Neuroepithelial Stem Cell (NESC) lines. Morphologically, the derived NESCs displayed rosette structures in culture and expressed key neural stem cell markers. Also, the transcriptomic profile of derived lines displayed similarity that proposes the homogeneity of our NESC population despite patient genomic background variation. We have used a healthy control NESC line to model Alzheimer’s Disease (AD) in a dish by exogenous application of amyloid beta oligomers in differentiating culture. Interestingly, AD-related phenotype, dis-localisation of phosphorylated P21-activated kinases (pPAK) protein, was recapitulated only in 3D culture. We further attempted to identify mechanisms underlying Type 1 Lissencephaly from patients carrying Doublecortin (DCX) mutations. Differentiating patients’ cells with dis-regulation of DCX expression exhibited a migrational defect, aberrant neurite outgrowth, and fewer dendrite bundles. In addition, we have dissected a proliferation phenotype of DCX mutant cells upon differentiation. Data suggests an indispensable role of DCX expression at an early stage of neural development which allows proper differentiation and migration. Here we have shown that it is possible to make a robust cellular model to study human brain disorders using patient-specific cells. Identification and verification of disease phenotypes and exploring the underlying mechanisms could provide valuable insights into these complex disorders. These insights may offer novel approaches to therapeutic applications taking scientists one step closer to treating the patients. This study underlines the importance of cellular-based models, 2D and 3D, that can be used to study typical development as well as disease mechanisms.
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| 5. |
- Sobol, Maria, et al.
(författare)
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Transcriptome and Proteome Profiling of Neural Induced Pluripotent Stem Cells from Individuals with Down Syndrome Disclose Dynamic Dysregulations of Key Pathways and Cellular Functions
- 2019
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Ingår i: Molecular Neurobiology. - : Springer Science and Business Media LLC. - 0893-7648 .- 1559-1182. ; 56:10, s. 7113-7127
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Tidskriftsartikel (refereegranskat)abstract
- Down syndrome (DS) or trisomy 21 (T21) is a leading genetic cause of intellectual disability. To gain insights into dynamics of molecular perturbations during neurogenesis in DS, we established a model using induced pluripotent stem cells (iPSC) with transcriptome profiles comparable to that of normal fetal brain development. When applied on iPSCs with T21, transcriptome and proteome signatures at two stages of differentiation revealed strong temporal dynamics of dysregulated genes, proteins and pathways belonging to 11 major functional clusters. DNA replication, synaptic maturation and neuroactive clusters were disturbed at the early differentiation time point accompanied by a skewed transition from the neural progenitor cell stage and reduced cellular growth. With differentiation, growth factor and extracellular matrix, oxidative phosphorylation and glycolysis emerged as major perturbed clusters. Furthermore, we identified a marked dysregulation of a set of genes encoded by chromosome 21 including an early upregulation of the hub gene APP, supporting its role for disturbed neurogenesis, and the transcription factors OLIG1, OLIG2 and RUNX1, consistent with deficient myelination and neuronal differentiation. Taken together, our findings highlight novel sequential and differentiation-dependent dynamics of disturbed functions, pathways and elements in T21 neurogenesis, providing further insights into developmental abnormalities of the DS brain.
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