TGF-β signaling promotes astroglial activation and TDP-43 proteinopathy in organoid models of frontotemporal lobar degeneration
Arren C. Ramsey, Xiao-Yan Tang, Magdalena J. Macias, Patricia R. Nano, Rufei Lu, Brian Benito, Cameron M. Lau, Jisu Park, Jiasheng Zhang, Wandy Beatty, Tanzila Mukhtar, Arnold R. Kriegstein, Aparna Bhaduri, Elise Marsan, Eric J. Huang
Arren C. Ramsey, Xiao-Yan Tang, Magdalena J. Macias, Patricia R. Nano, Rufei Lu, Brian Benito, Cameron M. Lau, Jisu Park, Jiasheng Zhang, Wandy Beatty, Tanzila Mukhtar, Arnold R. Kriegstein, Aparna Bhaduri, Elise Marsan, Eric J. Huang
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Research Article Aging Neuroscience

TGF-β signaling promotes astroglial activation and TDP-43 proteinopathy in organoid models of frontotemporal lobar degeneration

Abstract

Dominant mutations in progranulin (GRN) gene cause frontotemporal lobar degeneration (FTLD-GRN), whereas homozygous GRN mutations lead to neuronal ceroid lipofuscinosis, a childhood neurodegenerative disorder. While recent transcriptomic studies reveal profound glial and neuronal pathology in FTLD-GRN at the disease end stage, the mechanism that disrupts glia-neuron homeostasis remains unclear. Using induced pluripotent stem cell–derived cortical organoids, we showed that GRN–/– and GRNR493X mutations led to precocious astrogliosis that promoted neuronal stress and synaptic loss. Single-cell transcriptomics and histopathology analyses revealed a robust activation in the TGF-β signaling pathway in GRN–/– and GRNR493X/R493X astrocytes, which was accompanied by features of immune activation, loss of synaptic support, and abundant pTDP-43+ fibrils in astroglial cytoplasm, a feature characteristic of FTLD-GRN. Intriguingly, blocking TGF-β signaling mitigated astroglial activation and pTDP-43 proteinopathy in GRN–/– organoids. Together, these results provide insights into the cell-autonomous role of astroglial activation in neurodegeneration caused by progranulin deficiency.

Authors

Arren C. Ramsey, Xiao-Yan Tang, Magdalena J. Macias, Patricia R. Nano, Rufei Lu, Brian Benito, Cameron M. Lau, Jisu Park, Jiasheng Zhang, Wandy Beatty, Tanzila Mukhtar, Arnold R. Kriegstein, Aparna Bhaduri, Elise Marsan, Eric J. Huang

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Figure 1

Modeling progranulin deficiency in neurodevelopment using iPSC-derived cortical organoids.

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Modeling progranulin deficiency in neurodevelopment using iPSC-derived c...
(A) Schematic representation of the generation and analysis of iPSC-derived GRN+/+ and GRN–/– cortical organoids. (B) Confocal images of DCX, Ki-67, and SOX2 in GRN+/+ and GRN–/– cortical organoids at 5, 10, 16, and 25 weeks. DCX, doublecortin. (C) Percentage of organoids exhibiting different rosette morphologies at various developmental time points in GRN+/+ and GRN–/– cases. Rosette morphologies are categorized by average rosette radius: <50 μm (black), >50 μm (gray), VZ-like morphology (white), and no rosettes (striped). Organoids (n = 9) from 3 independent biological replicate experiments were analyzed per time point for each genotype. VZ, ventricular zone. (D) Quantification of the density of SOX2+DCX– radial glia cells at different time points in GRN+/+ (blue) and GRN–/– (red) groups. Inset shows the percentage of Ki-67+ cells among SOX2+DCX– radial glia over time, with no significant differences (NS) observed between groups. Organoids (n = 9) from 3 independent biological replicate experiments were analyzed per time point per genotype. (E) Confocal images of DCX, Ki-67, and SOX2 in GRN–/– and GRN+/+ iPSC-derived cortical organoids at different developmental time points. (F) Confocal images of CTIP2, SATB2 in GRN–/– and GRN+/+ iPSC-derived cortical organoids at different time points. (G) Percentage of CTIP2+SATB2– deep-layer neurons and CTIP2–SATB2+ upper-layer neurons at different time points in GRN+/+ (blue) and GRN–/– (red) groups. Organoids (n = 9) from 3 independent biological replicate experiments were analyzed per time point for each genotype. (H) Confocal images of glial fibrillary acidic protein (GFAP), S100β, SOX9, and NESTIN (NES) in GRN–/– and GRN+/+ iPSC-derived cortical organoids at different time points. (I) Percentage of NES+SOX9–S100β+ differentiating astrocytes and NES–SOX9+S100β+ mature astrocytes at different time points in GRN+/+ (blue) and GRN–/– (red) groups. Organoids (n = 9) from 3 independent biological replicates were analyzed per time point per genotype. All data represent mean ± SEM.