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 4

MultiNicheNet analyses of the signaling mechanisms mediating cell-cell communications in GRN+/+ and GRN–/– cortical organoids.

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MultiNicheNet analyses of the signaling mechanisms mediating cell-cell c...
(A) Heatmap of astrocyte-to-astrocyte ligand-receptor pairs split by age and genotype. (B) Violin plots for the expression of TGFB1, ITGB1, ITGAV, SDC2, CD44, and FN1 in GRN+/+ and GRN–/– astrocytes. Data represent mean + SEM. (C and D) Confocal images and quantification of SOX9+pSMAD3+ cells in GRN+/+ and GRN–/– cortical organoids at 25 weeks. (E and F) Confocal images and quantification of NF-κB mean fluorescence intensity (MFI) in GRN+/+ and GRN–/– iPSC-derived cortical organoids at 25 weeks. (G and H) Confocal images and quantification of pTDP-43+SOX9+ cells in GRN+/+ and GRN–/– cortical organoids at 25 weeks. In addition, confocal images of TDP-43, pTDP-43, and GFAP in 25 weeks GRN+/+ and GRN–/– organoids show nuclear depletion of TDP-43 and the presence cytoplasmic pTDP-43 in GFAP+ GRN–/– astrocytes. All data represent mean ± SEM. (I) Immuno-gold electron microscopy (IEM) of total TDP-43 (left column) and pTDP-43 (right column) in GRN+/+ and GRN–/– cortical organoids at 25 weeks. Arrows in first image highlight TDP-43+ structures in the nucleus of a GRN+/+ astrocyte, whereas arrowheads highlight many total TDP-43+ and pTDP-43+ structures in GRN–/– astrocytes (middle). (J) Western blots and quantification of the relative abundance of pSMAD3, pNF-κB, CD44, pTDP-43, and TTBK2 in GRN+/+ and GRN–/– cortical organoids at 25 weeks. Statistics used Student’s t test; data represent mean ± SEM.