9 results on '"Gunhanlar N"'
Search Results
2. A simplified protocol for differentiation of electrophysiologically mature neuronal networks from human induced pluripotent stem cells
- Author
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Gunhanlar, N, primary, Shpak, G, additional, van der Kroeg, M, additional, Gouty-Colomer, L A, additional, Munshi, S T, additional, Lendemeijer, B, additional, Ghazvini, M, additional, Dupont, C, additional, Hoogendijk, W J G, additional, Gribnau, J, additional, de Vrij, F M S, additional, and Kushner, S A, additional
- Published
- 2017
- Full Text
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3. A simplified protocol for differentiation of electrophysiologically mature neuronal networks from human induced pluripotent stem cells
- Author
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Gunhanlar, N, Shpak, G, van der Kroeg, M, Gouty-Colomer, L A, Munshi, S T, Lendemeijer, B, Ghazvini, M, Dupont, C, Hoogendijk, W J G, Gribnau, J, de Vrij, F M S, and Kushner, S A
- Abstract
Progress in elucidating the molecular and cellular pathophysiology of neuropsychiatric disorders has been hindered by the limited availability of living human brain tissue. The emergence of induced pluripotent stem cells (iPSCs) has offered a unique alternative strategy using patient-derived functional neuronal networks. However, methods for reliably generating iPSC-derived neurons with mature electrophysiological characteristics have been difficult to develop. Here, we report a simplified differentiation protocol that yields electrophysiologically mature iPSC-derived cortical lineage neuronal networks without the need for astrocyte co-culture or specialized media. This protocol generates a consistent 60:40 ratio of neurons and astrocytes that arise from a common forebrain neural progenitor. Whole-cell patch-clamp recordings of 114 neurons derived from three independent iPSC lines confirmed their electrophysiological maturity, including resting membrane potential (−58.2±1.0 mV), capacitance (49.1±2.9 pF), action potential (AP) threshold (−50.9±0.5 mV) and AP amplitude (66.5±1.3 mV). Nearly 100% of neurons were capable of firing APs, of which 79% had sustained trains of mature APs with minimal accommodation (peak AP frequency: 11.9±0.5 Hz) and 74% exhibited spontaneous synaptic activity (amplitude, 16.03±0.82 pA; frequency, 1.09±0.17 Hz). We expect this protocol to be of broad applicability for implementing iPSC-based neuronal network models of neuropsychiatric disorders.
- Published
- 2018
- Full Text
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4. Monocarboxylate Transporter 8 Deficiency: From Pathophysiological Understanding to Therapy Development.
- Author
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van Geest FS, Gunhanlar N, Groeneweg S, and Visser WE
- Subjects
- Humans, Mental Retardation, X-Linked mortality, Mental Retardation, X-Linked pathology, Monocarboxylic Acid Transporters genetics, Muscle Hypotonia mortality, Muscle Hypotonia pathology, Muscular Atrophy mortality, Muscular Atrophy pathology, Phenotype, Signal Transduction genetics, Symporters genetics, Therapies, Investigational methods, Therapies, Investigational trends, Mental Retardation, X-Linked genetics, Mental Retardation, X-Linked therapy, Muscle Hypotonia genetics, Muscle Hypotonia therapy, Muscular Atrophy genetics, Muscular Atrophy therapy
- Abstract
Genetic defects in the thyroid hormone transporter monocarboxylate transporter 8 (MCT8) result in MCT8 deficiency. This disorder is characterized by a combination of severe intellectual and motor disability, caused by decreased cerebral thyroid hormone signalling, and a chronic thyrotoxic state in peripheral tissues, caused by exposure to elevated serum T3 concentrations. In particular, MCT8 plays a crucial role in the transport of thyroid hormone across the blood-brain-barrier. The life expectancy of patients with MCT8 deficiency is strongly impaired. Absence of head control and being underweight at a young age, which are considered proxies of the severity of the neurocognitive and peripheral phenotype, respectively, are associated with higher mortality rate. The thyroid hormone analogue triiodothyroacetic acid is able to effectively and safely ameliorate the peripheral thyrotoxicosis; its effect on the neurocognitive phenotype is currently under investigation. Other possible therapies are at a pre-clinical stage. This review provides an overview of the current understanding of the physiological role of MCT8 and the pathophysiology, key clinical characteristics and developing treatment options for MCT8 deficiency., Competing Interests: The Erasmus Medical Centre (Rotterdam, Netherlands), which employs FSvG, NG, SG, and WEV receives royalties from Rare Thyroid Therapeutics (the manufacturer of Triac), dependent on commercialisation. None of the authors will benefit personally from any royalties. None of the authors have personal disclosures relevant to this work., (Copyright © 2021 van Geest, Gunhanlar, Groeneweg and Visser.)
- Published
- 2021
- Full Text
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5. Candidate CSPG4 mutations and induced pluripotent stem cell modeling implicate oligodendrocyte progenitor cell dysfunction in familial schizophrenia.
- Author
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de Vrij FM, Bouwkamp CG, Gunhanlar N, Shpak G, Lendemeijer B, Baghdadi M, Gopalakrishna S, Ghazvini M, Li TM, Quadri M, Olgiati S, Breedveld GJ, Coesmans M, Mientjes E, de Wit T, Verheijen FW, Beverloo HB, Cohen D, Kok RM, Bakker PR, Nijburg A, Spijker AT, Haffmans PMJ, Hoencamp E, Bergink V, Vorstman JA, Wu T, Olde Loohuis LM, Amin N, Langen CD, Hofman A, Hoogendijk WJ, van Duijn CM, Ikram MA, Vernooij MW, Tiemeier H, Uitterlinden AG, Elgersma Y, Distel B, Gribnau J, White T, Bonifati V, and Kushner SA
- Subjects
- Adult, Antigens genetics, Cell Differentiation physiology, Chondroitin Sulfate Proteoglycans metabolism, Diffusion Tensor Imaging, Family, Female, Humans, Induced Pluripotent Stem Cells metabolism, Male, Membrane Proteins metabolism, Mutation genetics, Oligodendrocyte Precursor Cells physiology, Oligodendroglia metabolism, Pedigree, Proteoglycans genetics, Schizophrenia metabolism, White Matter metabolism, Chondroitin Sulfate Proteoglycans genetics, Membrane Proteins genetics, Oligodendrocyte Precursor Cells metabolism, Schizophrenia genetics
- Abstract
Schizophrenia is highly heritable, yet its underlying pathophysiology remains largely unknown. Among the most well-replicated findings in neurobiological studies of schizophrenia are deficits in myelination and white matter integrity; however, direct etiological genetic and cellular evidence has thus far been lacking. Here, we implement a family-based approach for genetic discovery in schizophrenia combined with functional analysis using induced pluripotent stem cells (iPSCs). We observed familial segregation of two rare missense mutations in Chondroitin Sulfate Proteoglycan 4 (CSPG4) (c.391G > A [p.A131T], MAF 7.79 × 10
-5 and c.2702T > G [p.V901G], MAF 2.51 × 10-3 ). The CSPG4A131T mutation was absent from the Swedish Schizophrenia Exome Sequencing Study (2536 cases, 2543 controls), while the CSPG4V901G mutation was nominally enriched in cases (11 cases vs. 3 controls, P = 0.026, OR 3.77, 95% CI 1.05-13.52). CSPG4/NG2 is a hallmark protein of oligodendrocyte progenitor cells (OPCs). iPSC-derived OPCs from CSPG4A131T mutation carriers exhibited abnormal post-translational processing (P = 0.029), subcellular localization of mutant NG2 (P = 0.007), as well as aberrant cellular morphology (P = 3.0 × 10-8 ), viability (P = 8.9 × 10-7 ), and myelination potential (P = 0.038). Moreover, transfection of healthy non-carrier sibling OPCs confirmed a pathogenic effect on cell survival of both the CSPG4A131T (P = 0.006) and CSPG4V901G (P = 3.4 × 10-4 ) mutations. Finally, in vivo diffusion tensor imaging of CSPG4A131T mutation carriers demonstrated a reduction of brain white matter integrity compared to unaffected sibling and matched general population controls (P = 2.2 × 10-5 ). Together, our findings provide a convergence of genetic and functional evidence to implicate OPC dysfunction as a candidate pathophysiological mechanism of familial schizophrenia.- Published
- 2019
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6. SOX10 Single Transcription Factor-Based Fast and Efficient Generation of Oligodendrocytes from Human Pluripotent Stem Cells.
- Author
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García-León JA, Kumar M, Boon R, Chau D, One J, Wolfs E, Eggermont K, Berckmans P, Gunhanlar N, de Vrij F, Lendemeijer B, Pavie B, Corthout N, Kushner SA, Dávila JC, Lambrichts I, Hu WS, and Verfaillie CM
- Subjects
- Amyotrophic Lateral Sclerosis genetics, Amyotrophic Lateral Sclerosis therapy, Antigens, Surface genetics, Gene Expression Regulation, Developmental, Humans, Multiple Sclerosis genetics, Multiple Sclerosis pathology, Multiple Sclerosis therapy, Myelin Basic Protein genetics, Neurons pathology, Neurons transplantation, Oligodendroglia cytology, Oligodendroglia transplantation, Pluripotent Stem Cells cytology, Pluripotent Stem Cells transplantation, Transcriptome genetics, Cell Differentiation genetics, Oligodendroglia metabolism, Pluripotent Stem Cells metabolism, SOXE Transcription Factors genetics
- Abstract
Scarce access to primary samples and lack of efficient protocols to generate oligodendrocytes (OLs) from human pluripotent stem cells (hPSCs) are hampering our understanding of OL biology and the development of novel therapies. Here, we demonstrate that overexpression of the transcription factor SOX10 is sufficient to generate surface antigen O4-positive (O4
+ ) and myelin basic protein-positive OLs from hPSCs in only 22 days, including from patients with multiple sclerosis or amyotrophic lateral sclerosis. The SOX10-induced O4+ population resembles primary human OLs at the transcriptome level and can myelinate neurons in vivo. Using in vitro OL-neuron co-cultures, myelination of neurons by OLs can also be demonstrated, which can be adapted to a high-throughput screening format to test the response of pro-myelinating drugs. In conclusion, we provide an approach to generate OLs in a very rapid and efficient manner, which can be used for disease modeling, drug discovery efforts, and potentially for therapeutic OL transplantation., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)- Published
- 2018
- Full Text
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7. Epigenetic characterization of the FMR1 promoter in induced pluripotent stem cells from human fibroblasts carrying an unmethylated full mutation.
- Author
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de Esch CE, Ghazvini M, Loos F, Schelling-Kazaryan N, Widagdo W, Munshi ST, van der Wal E, Douben H, Gunhanlar N, Kushner SA, Pijnappel WW, de Vrij FM, Geijsen N, Gribnau J, and Willemsen R
- Subjects
- Adolescent, Animals, Case-Control Studies, Cell Line, Cellular Reprogramming, Child, Child, Preschool, Female, Fibroblasts cytology, Fragile X Mental Retardation Protein metabolism, Histones metabolism, Humans, Induced Pluripotent Stem Cells cytology, Male, Mice, Promoter Regions, Genetic, RNA, Messenger genetics, RNA, Messenger metabolism, DNA Methylation, Fibroblasts metabolism, Fragile X Mental Retardation Protein genetics, Gene Silencing, Induced Pluripotent Stem Cells metabolism, Mutation
- Abstract
Silencing of the FMR1 gene leads to fragile X syndrome, the most common cause of inherited intellectual disability. To study the epigenetic modifications of the FMR1 gene during silencing in time, we used fibroblasts and induced pluripotent stem cells (iPSCs) of an unmethylated full mutation (uFM) individual with normal intelligence. The uFM fibroblast line carried an unmethylated FMR1 promoter region and expressed normal to slightly increased FMR1 mRNA levels. The FMR1 expression in the uFM line corresponds with the increased H3 acetylation and H3K4 methylation in combination with a reduced H3K9 methylation. After reprogramming, the FMR1 promoter region was methylated in all uFM iPSC clones. Two clones were analyzed further and showed a lack of FMR1 expression, whereas the presence of specific histone modifications also indicated a repressed FMR1 promoter. In conclusion, these findings demonstrate that the standard reprogramming procedure leads to epigenetic silencing of the fully mutated FMR1 gene., (Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2014
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8. The pluripotency factor-bound intron 1 of Xist is dispensable for X chromosome inactivation and reactivation in vitro and in vivo.
- Author
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Minkovsky A, Barakat TS, Sellami N, Chin MH, Gunhanlar N, Gribnau J, and Plath K
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- Animals, Cell Differentiation, Cellular Reprogramming, Embryonic Stem Cells metabolism, Gene Deletion, Gene Expression Regulation, Developmental, Mice, RNA, Long Noncoding genetics, Transcription Factors metabolism, Transcription, Genetic, Up-Regulation, Introns, RNA, Long Noncoding metabolism, X Chromosome Inactivation
- Abstract
X chromosome inactivation (XCI) is a dynamically regulated developmental process with inactivation and reactivation accompanying the loss and gain of pluripotency, respectively. A functional relationship between pluripotency and lack of XCI has been suggested, whereby pluripotency transcription factors repress the master regulator of XCI, the noncoding transcript Xist, by binding to its first intron (intron 1). To test this model, we have generated intron 1 mutant embryonic stem cells (ESCs) and two independent mouse models. We found that Xist's repression in ESCs, its transcriptional upregulation upon differentiation, and its silencing upon reprogramming to pluripotency are not dependent on intron 1. Although we observed subtle effects of intron 1 deletion on the randomness of XCI and in the absence of the antisense transcript Tsix in differentiating ESCs, these have little relevance in vivo because mutant mice do not deviate from Mendelian ratios of allele transmission. Altogether, our findings demonstrate that intron 1 is dispensable for the developmental dynamics of Xist expression., (Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2013
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9. RNF12 activates Xist and is essential for X chromosome inactivation.
- Author
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Barakat TS, Gunhanlar N, Pardo CG, Achame EM, Ghazvini M, Boers R, Kenter A, Rentmeester E, Grootegoed JA, and Gribnau J
- Subjects
- Animals, Embryonic Stem Cells metabolism, Female, Fluorescent Antibody Technique, Gene Expression Profiling, Gene Expression Regulation, Developmental, Genetic Vectors, Homeodomain Proteins genetics, Homeodomain Proteins metabolism, In Situ Hybridization, Fluorescence, Introns genetics, Male, Mice, Nanog Homeobox Protein, RNA, Long Noncoding, Repressor Proteins genetics, Ubiquitin-Protein Ligases, Gene Silencing, RNA, Untranslated genetics, Repressor Proteins physiology, X Chromosome Inactivation genetics
- Abstract
In somatic cells of female placental mammals, one of the two X chromosomes is transcriptionally silenced to accomplish an equal dose of X-encoded gene products in males and females. Initiation of random X chromosome inactivation (XCI) is thought to be regulated by X-encoded activators and autosomally encoded suppressors controlling Xist. Spreading of Xist RNA leads to silencing of the X chromosome in cis. Here, we demonstrate that the dose dependent X-encoded XCI activator RNF12/RLIM acts in trans and activates Xist. We did not find evidence for RNF12-mediated regulation of XCI through Tsix or the Xist intron 1 region, which are both known to be involved in inhibition of Xist. In addition, we found that Xist intron 1, which contains a pluripotency factor binding site, is not required for suppression of Xist in undifferentiated ES cells. Analysis of female Rnf12⁻/⁻ knockout ES cells showed that RNF12 is essential for initiation of XCI and is mainly involved in the regulation of Xist. We conclude that RNF12 is an indispensable factor in up-regulation of Xist transcription, thereby leading to initiation of random XCI., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2011
- Full Text
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