Dataset Information

Distinct Neurodegenerative Changes in an Induced Pluripotent Stem Cell Model of Frontotemporal Dementia Linked to Mutant TAU Protein.

ABSTRACT: Frontotemporal dementia (FTD) is a frequent form of early-onset dementia and can be caused by mutations in MAPT encoding the microtubule-associated protein TAU. Because of limited availability of neural cells from patients' brains, the underlying mechanisms of neurodegeneration in FTD are poorly understood. Here, we derived induced pluripotent stem cells (iPSCs) from individuals with FTD-associated MAPT mutations and differentiated them into mature neurons. Patient iPSC-derived neurons demonstrated pronounced TAU pathology with increased fragmentation and phospho-TAU immunoreactivity, decreased neurite extension, and increased but reversible oxidative stress response to inhibition of mitochondrial respiration. Furthermore, FTD neurons showed an activation of the unfolded protein response, and a transcriptome analysis demonstrated distinct, disease-associated gene expression profiles. These findings indicate distinct neurodegenerative changes in FTD caused by mutant TAU and highlight the unique opportunity to use neurons differentiated from patient-specific iPSCs to identify potential targets for drug screening purposes and therapeutic intervention.

SUBMITTER: Ehrlich M

PROVIDER: S-EPMC4618448 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

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Distinct Neurodegenerative Changes in an Induced Pluripotent Stem Cell Model of Frontotemporal Dementia Linked to Mutant TAU Protein.

Ehrlich Marc M Hallmann Anna-Lena AL Reinhardt Peter P Araúzo-Bravo Marcos J MJ Korr Sabrina S Röpke Albrecht A Psathaki Olympia E OE Ehling Petra P Meuth Sven G SG Oblak Adrian L AL Murrell Jill R JR Ghetti Bernardino B Zaehres Holm H Schöler Hans R HR Sterneckert Jared J Kuhlmann Tanja T Hargus Gunnar G

Stem cell reports 20150702 1

Frontotemporal dementia (FTD) is a frequent form of early-onset dementia and can be caused by mutations in MAPT encoding the microtubule-associated protein TAU. Because of limited availability of neural cells from patients' brains, the underlying mechanisms of neurodegeneration in FTD are poorly understood. Here, we derived induced pluripotent stem cells (iPSCs) from individuals with FTD-associated MAPT mutations and differentiated them into mature neurons. Patient iPSC-derived neurons demonstra ...[more]

PMID: 26143746

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Project description:Frontotemporal dementia (FTD) is a frequent form of early-onset dementia and can be caused by mutations in MAPT encoding the microtubule-associated protein tau. Due to limited availability of neural cells from patients` brains, however, the underlying mechanisms of neurodegeneration in FTD are still only poorly understood. Here, we derived induced pluripotent stem (iPS) cells from individuals with FTD-associated MAPT mutations and differentiated them into neurons for mechanistic studies. Patient-derived neurons demonstrated pronounced tau pathology with increased fragmentation and AT8-immunoreactivity, disturbed neurite extension and increased but reversible oxidative stress response to inhibition of mitochondrial respiration. Furthermore, FTD-neurons showed activation of the unfolded protein response and presented with distinct, disease-associated gene expression profiles in a whole-genome transcriptome analysis. These findings indicate distinct, early neurodegenerative changes in FTD caused by mutant tau and highlight the unique opportunity to use patient-specific iPS cells to identify potential targets for drug screening purposes and therapeutic intervention. RNA samples for microarray analysis were prepared using RNeasy columns (Qiagen, Germany) with on-column DNA digestion. 300 ng of total RNA per sample were used as the input in the linear amplification protocol (Ambion), which involved the synthesis of T7-linked double-stranded cDNAs and 12hrs of in vitro transcription incorporating biotin-labeled nucleotides. Purified and labeled cRNA was then hybridized for 18 hrs onto HumanHT-12 v4 expression BeadChips (Illumina, USA) following the manufacturer’s instructions. After the recommended washing, the chips were stained with streptavidin-Cy3 (GE Healthcare) and scanned using the iScan reader (Illumina) and the accompanying software. The samples were exclusively hybridized as biological replicates. The bead intensities were mapped to the corresponding gene information using BeadStudio 3.2 (Illumina) and background correction was performed using the Affymetrix Robust Multi-array Analysis (RMA) background correction model (Irizarry et al., 2003). Variance stabilization was performed using the log2 scaling, and gene expression normalization was calculated with the quantile method implemented in the lumi package of R-Bioconductor. Data post-processing and graphics were performed with in-house developed functions in MATLAB. Hierarchical clusters of genes and samples were performed with the one minus the sample correlation metric and the Unweighted Pair-Group Method using Average (UPGMA) linkage method.

Project description:BackgroundPallido-ponto-nigral degeneration (PPND), a major subtype of frontotemporal dementia with parkinsonism related to chromosome 17 (FTDP-17), is a progressive and terminal neurodegenerative disease caused by c.837 T > G mutation in the MAPT gene encoding microtubule-associated protein tau (rs63750756; N279K). This MAPT mutation induces alternative splicing of exon 10, resulting in a modification of microtubule-binding region of tau. Although mutations in the MAPT gene have been linked to multiple tauopathies including Alzheimer's disease, frontotemporal dementia and progressive supranuclear palsy, knowledge regarding how tau N279K mutation causes PPND/FTDP-17 is limited.ResultsWe investigated the underlying disease mechanism associated with the N279K tau mutation using PPND/FTDP-17 patient-derived induced pluripotent stem cells (iPSCs) and autopsy brains. In iPSC-derived neural stem cells (NSCs), the N279K tau mutation induced an increased ratio of 4-repeat to 3-repeat tau and accumulation of stress granules indicating elevated cellular stress. More significant, NSCs derived from patients with the N279K tau mutation displayed impaired endocytic trafficking as evidenced by accumulation of endosomes and exosomes, and a reduction of lysosomes. Since there were no significant differences in cellular stress and distribution of subcellular organelles between control and N279K skin fibroblasts, N279K-related vesicle trafficking defects are likely specific to the neuronal lineage. Consistently, the levels of intracellular/luminal vesicle and exosome marker flotillin-1 were significantly increased in frontal and temporal cortices of PPND/FTDP-17 patients with the N279K tau mutation, events that were not seen in the occipital cortex which is the most spared cortical region in the patients.ConclusionTogether, our results demonstrate that alterations of intracellular vesicle trafficking in NSCs/neurons likely contribute to neurodegeneration as an important disease mechanism underlying the N279K tau mutation in PPND/FTDP-17.

Project description:Common neurodegenerative diseases feature progressive accumulation of disease-specific protein aggregates in selectively vulnerable brain regions. Increasing experimental evidence suggests that misfolded disease proteins exhibit prion-like properties, including the ability to seed corruptive templating and self-propagation along axons. Direct evidence for transneuronal spread in patients, however, remains limited. To test predictions made by the transneuronal spread hypothesis in human tissues, we asked whether tau deposition within axons of the corticospinal and corticopontine pathways can be predicted based on clinical syndromes and cortical atrophy patterns seen in frontotemporal lobar degeneration (FTLD). Sixteen patients with Pick's disease, 21 with corticobasal degeneration, and 3 with FTLD-MAPT were included, spanning a range of clinical syndromes across the frontotemporal dementia (FTD) spectrum. Cortical involvement was measured using a neurodegeneration score, a tau score, and a composite score based on semiquantitative ratings and complemented by an MRI-based cortical atrophy W-map based on antemortem imaging. Midbrain cerebral peduncle and pontine base descending fibers were divided into three subregions, representing prefrontopontine, corticospinal, and parieto-temporo-occipital fiber pathways. Tau area fraction was calculated in each subregion and related to clinical syndrome and cortical measures. Within each clinical syndrome, there were predicted relationships between cortical atrophy patterns and axonal tau deposition in midbrain cerebral peduncle and pontine base. Between syndromes, contrasting and predictable patterns of brainstem axonal tau deposition emerged, with, for example, greater tau in prefrontopontine fibers in behavioral variant FTD and in corticospinal fibers in corticobasal syndrome. Finally, semiquantitative and quantitative cortical degeneration scores predicted brainstem axonal tau deposition based on anatomical principles. Taken together, these findings provide important human evidence in support of axonal tau spreading in patients with specific forms of tau-related neurodegeneration.

Dataset Information

Distinct Neurodegenerative Changes in an Induced Pluripotent Stem Cell Model of Frontotemporal Dementia Linked to Mutant TAU Protein.

Publications

Distinct Neurodegenerative Changes in an Induced Pluripotent Stem Cell Model of Frontotemporal Dementia Linked to Mutant TAU Protein.

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