Neuronal hyperactivity becomes mTORC1 independent due to epigenetic changes in Tuberous Sclerosis Complex
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE286912 | GEO | 2025/10/25
REPOSITORIES: GEO
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Project description:Tuberous Sclerosis Complex (TSC) is caused by variants in either TSC1 or TSC2, which cooperate to inhibit the mechanistic target of rapamycin complex 1 (mTORC1). TSC is associated with neurological disorders that have been attributed to disinhibition of mTORC1, but mechanisms connecting dysregulation of mTORC1 to molecular and physiological changes in neurons remain unclear. In this study, we sought to understand transcriptional changes in TSC and identified down-regulation of the immediate early gene, EGR1, in TSC2-deficient excitatory neurons. Furthermore, we found that activity-dependent transcription is impaired in TSC due to abnormalities in epigenetic maturation. Finally, we determined that mTORC1 inhibition started late in neuronal maturation of human neurons is only partially effective in reversing gene expression changes and ineffective in reducing spontaneous neuronal hyperactivity in TSC. These data demonstrate a critical window in early brain development where mTORC1 dysregulation leads to epigenetic changes that contribute to persistent neuronal abnormalities.
2025-10-25 | GSE286949 | GEO
Project description:Tuberous Sclerosis Complex (TSC) is a disease caused by autosomal dominant mutations in the TSC1 or TSC2 genes, and is characterized by tumor susceptibility, brain lesions, seizures and behavioral impairments. The TSC1 and TSC2 genes encode proteins forming a complex (TSC), which is a major regulator and suppressor of mammalian target of rapamycin (mTOR) in complex 1 (mTORC1), a signaling complex that promotes cell growth and proliferation. TSC1/2 loss of heterozygosity (LOH) and the subsequent complete loss of TSC regulatory activity in null cells causes mTORC1 dysregulation and TSC-associated brain lesions or other tissue tumors. However, it is not clear whether TSC1/2 heterozygous brain cells are abnormal and contribute to TSC neuropathology. To investigate this issue, we generated induced pluripotent stem cells (iPSCs) from TSC patients and unaffected controls, and utilized these to obtain neural progenitor cells (NPCs) and differentiated neurons in vitro. These patient-derived TSC2 heterozygous NPCs were delayed in their ability to differentiate into neurons. Patient-derived progenitor cells also exhibited a modest activation of mTORC1 signaling downstream of TSC, and a marked attenuation of upstream PI3K/AKT signaling. We further show that pharmacologic AKT inhibition, but not mTORC1 inhibition, causes a neuronal differentiation delay, mimicking the patient phenotype. Together these data suggest that heterozygous TSC2 mutations disrupt neuronal development, potentially contributing to the disease neuropathology, and that this defect may result from dysregulated AKT signaling in neural progenitor cells.
2018-08-26 | GSE111584 | GEO
Project description:Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder caused by mutations in either TSC1 or TSC2, presenting with systemic growth of benign tumors. In addition to the brain lesions, neurologic impairment causes the greatest morbidity in TSC patients. Up to 50% of TSC patients are affected with autism spectrum disorders (ASDs), including a wide range of autistic symptoms overlapping with that in idiopathic ASD patients. Examination of postmortem tissue uncovered activated microglia and neuroinflammation in the brains of TSC patients. Microglia are the resident immune cells of the central nervous system. Studies from animal or human stem cell models with TSC1/2 knockout suggest that TSC1/2 deficiency can cause hyper-activation of the mammalian target of rapamycin complex 1 (mTORC1) signaling, which may result in abnormal neurodevelopment. However, how the causal variants of TSC1/2 genes identified in TSC patients affect human microglia and how they contribute to the neurological manifestations in TSC remain largely unexplored. To address these questions, in this study, we generated human induced pluripotent stem cells-derived microglia (hiPSC-microglia) from TSC patients carrying TSC2 mutations as well as age- and sex-matched healthy controls for the first time. Bulk RNA sequencing (bulk-RNAseq), proteome, and phosphoproteome analyses of TSC microglia revealed that TSC2 mutations not only hyperactivate mTORC1 signaling pathway, but also alter lipid metabolism through the peroxisome proliferator-activated receptor (PPAR) signaling pathway driven by lipoprotein lipase (LPL) gene. This leads to dysregulated phagocytic capacities and pro-inflammatory responses, which further impair neuronal function including altered complexity of neuronal dendrites, dysregulated formation of morphological excitatory synapses and neuronal hyperexcitability. Additionally, unbiased lipidomics revealed alterations of glycerophosphocholines (GPC) and fatty acyls (FA) in TSC microglia. The developmental abnormalities i
2025-09-27 | GSE278357 | GEO
Project description:Tuberous Sclerosis Complex (TSC) is caused by germline TSC1 or TSC2 mutations, leading to hyperactivation of mechanistic target of rapamycin complex 1 (mTORC1) and tumors in multiple organs including the brain, heart, lung (lymphangioleiomyomatosis), and kidney (angiomyolipoma and renal cell carcinoma). Previously, we found that TFEB is constitutively active in models of TSC. To determine the impact of TFEB in vivo, we generated two novel mouse models of TSC, resulting in premature death, in which kidney pathology was the primary phenotype. RNA sequencing revealed that lysosomal and proteasomal gene pathways were the most highly upregulated in the TSC2-deficient kidneys. Knockout of TFEB rescued both kidney pathology and overall survival in both models, indicating that TFEB is the primary driver of renal disease in TSC. Importantly, mTORC1 activity, which was elevated in the TSC2 knockout kidneys, was normalized by TFEB knockout. Knockdown of Rheb or treatment of TSC2-deficient cells with Rapamycin paradoxically increases TFEB phosphorylation at the mTORC1-site (S211) and relocalizes TFEB from the nucleus to the cytoplasm via a Rag-dependent mechanism. Accordingly, treatment of TSC2 knockout mice with Rapamycin normalized lysosomal gene expression, similar to TFEB knockout, suggesting that the beneficial effects of Rapamycin in TSC are TFEB-dependent. These results change the view of the mechanisms leading to mTORC1 hyperactivation in TSC and may lead to novel therapeutic avenues for the treatment of TSC.
2023-09-28 | GSE244072 | GEO
Project description:Aberrant activation of the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) is a common molecular event in a large variety of pathological settings, including genetic tumor syndromes, cancer, and obesity. However, the cell intrinsic consequences of mTORC1 activation remain poorly defined. Here, we identify global trancriptional changes in TSC1 and TSC2 null MEFs, which exhibit constitutive activation of mTORC1, compared to wild-type littermate control lines. A rapamycin time course is included to determine those changes that are dependent on mTORC1 signaling, revealing mTORC1 induced and repressed transcripts. In order to identify mTORC1-dependent transcriptional changes, we compared wild-type MEFs to both Tsc1-/- and Tsc2-/- MEFs following serum starvation, where mTORC1 signaling is off in wild-type cells and fully active in TSC-deficient cells. All cell lines were serum-starved for 24 h, and the Tsc1-/- and Tsc2-/- cells were treated with a time course of rapamycin prior to the isolation of mRNA for microarray analysis. Immortalized wild-type (Tsc2+/+ p53-/-), Tsc1-/- (p53+/+, 3T3-immortalized), and Tsc2-/- (p53-/-, derived from a littermate of the wild-type cell line) MEFs are the three cell lines used in this study and were derived in the laboratory of David J. Kwiatkowski (Brigham and Women's Hospital, Harvard Medical School, Boston, MA). Wild-type and null MEFs were grown to 70% confluence in 10 cm plates and were serum starved for 24 h in the presence of vehicle (DMSO) for 24 h or rapamycin (20 nM) for 2, 6, 12, or 24 h. All vehicle-treated samples (0 h time points) were plated in triplicate and all rapamycin time course samples were plated in duplicate. For each replicate, expression analysis was performed by hybridization to an Affymetrix Mouse 430_2 oligonucleotide microarray chip.
2010-07-30 | E-GEOD-21755 | biostudies-arrayexpress
Project description:Tuberous sclerosis complex (TSC) is an inherited neurodevelopmental (ND) disorder with frequent manifestations of epilepsy and autism spectrum disorder (ASD) caused by mutations in TSC1 or TSC2 genes. TSC1 and TSC2 form a complex inhibiting mechanistic target of rapamycin complex-1 (mTORC1) signaling, leading to hyperactive mTORC1 signaling upon TSC1/2 loss of function. Although rapalogs, which are FDA-approved allosteric mTORC1-selective inhibitors, are used to treat TSC-associated hamartomas, they are not effective for treating ND manifestations. mTORC1 signaling controls protein synthesis by regulating formation of the eIF4F complex, whose activity is further modulated by the MNK1/2 kinases via phosphorylation of the eIF4F subunit eIF4E. While both these pathways modulate translation in transcript-selective fashion depending on features in target mRNAs’ 5’ untranslated regions (5’UTRs), their effect on transcriptome-wide patterns of mRNA translation has not been compared. Here, employing CRISPR-modified, isogenic TSC2 patient-derived neural progenitor cells (NPCs), we examined how loss of TSC2 affects gene expression via changes in mRNA abundance and translation at a transcriptome-wide scale. This revealed abundant mRNA translation alterations in TSC2-Null NPCs overlapping with those we previously observed in TSC1-Null NPCs. Surprisingly, numerous non-monogenic ASD- and NDD-associated genes, identified in patients harboring putative loss-of-function mutations, were selectively translationally suppressed in TSC2-Null NPCs consistent with their distinct repertoire of 5’UTR features. Importantly, translation of these ASD- and NDD-associated genes was reversed upon inhibition of either mTORC1 or MNK1/2 signaling using RMC-6272 or eFT-508, respectively. This study thereby establishes mTORC1-eIF4F and MNK-eIF4E-sensitive mRNA translation as key components in TSC, ASD and other neurodevelopmental disorders; and lay the groundwork for evaluating drugs in clinical development that target these pathways as a treatment strategy for TSC as well as ASD/NDD.
2025-03-06 | GSE277844 | GEO
Project description:Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by heterozygous pathogenic variants in either TSC1 or TSC2. Emerging evidence suggests a connection between microglia activation and epilepsy as well as cognitive impairment in TSC patients. However, the impact of the causal variants of TSC1/2 genes on human microglia and their contribution to TSC's neurological symptoms remain largely unexplored. In this study, we generated human microglia from induced pluripotent stem cells (iPSCs) from a TSC patient cohort. Through extensive molecular and cellular analysis of TSC microglia, including transcriptomics, proteomics/phosphopreteomics, and lipidomics, we found that heterozygous TSC2 pathogenic variants were sufficient to cause aberrant lipid metabolism marked by increased glycerophosphocholines and fatty acyls. These metabolic changes resulted in enhanced phagocytosis and inflammation. Strikingly, the dysregulated lipid metabolism in TSC microglia is driven by a hyper-activated mTOR-lipoprotein lipase (LPL) pathway. Further, cellular and electrophysiological assessments of neuron/microglia co-cultures revealed that TSC microglia directly affect neuronal development, excitability, and neuronal network activity, which could be largely ameliorated by mTOR/LPL inhibition. Collectively, our research unveiled the molecular and cellular abnormalities in TSC microglia affecting neuronal development and function, and highlighted the mTOR-LPL pathway as a novel potential therapeutic target for the neuropathology of TSC.
2023-09-27 | GSE244091 | GEO
Project description:Aberrant activation of the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) is a common molecular event in a large variety of pathological settings, including genetic tumor syndromes, cancer, and obesity. However, the cell intrinsic consequences of mTORC1 activation remain poorly defined. Here, we identify global trancriptional changes in TSC1 and TSC2 null MEFs, which exhibit constitutive activation of mTORC1, compared to wild-type littermate control lines. A rapamycin time course is included to determine those changes that are dependent on mTORC1 signaling, revealing mTORC1 induced and repressed transcripts. In order to identify mTORC1-dependent transcriptional changes, we compared wild-type MEFs to both Tsc1-/- and Tsc2-/- MEFs following serum starvation, where mTORC1 signaling is off in wild-type cells and fully active in TSC-deficient cells. All cell lines were serum-starved for 24 h, and the Tsc1-/- and Tsc2-/- cells were treated with a time course of rapamycin prior to the isolation of mRNA for microarray analysis.
2010-07-30 | GSE21755 | GEO
Project description:The tuberous sclerosis complex (TSC) family of tumor suppressors, TSC1 and TSC2, function together in an evolutionarily conserved protein complex that is a point of convergence for major cell signaling pathways that regulate mTOR complex 1 (mTORC1). Mutation or aberrant inhibition of the TSC complex is common in various human tumor syndromes and cancers. The discovery of novel therapeutic strategies to selectively target cells with functional loss of this complex is therefore of substantial clinical relevance to TSC and sporadic cancers. We developed a CRISPR-based method to generate homogenous mutant Drosophila cell lines. By combining TSC1 and TSC2 mutant cell lines with RNAi screens against all kinases and phosphatases, we identified synthetic interactions with TSC1 and TSC2. Knockdown of three candidate genes (mRNA-cap, Pitslre and CycT; orthologs of RNGTT, CDK11 and CCNT1 in humans) reduced the population growth rate of both Drosophila TSC1 and TSC2 mutant cells but not that of wild-type cells. Moreover, knockdown of all three genes displayed similar selective effects in mammalian TSC2-deficient cell lines, including human tumor-derived cells, illustrating the power of this cross species screening strategy to identify potential drug targets.
2018-10-24 | PXD002670 | Pride
Project description:Tuberous Sclerosis Complex (TSC) is a debilitating developmental disorder characterized by a variety of clinical manifestations. While benign tumors in the heart, lungs, kidney, and brain are all hallmarks of the disease, often the most severe symptoms of TSC are neurological, including seizures, autism, psychiatric disorders, and intellectual disabilities. TSC is caused by a heterozygous loss of function mutation in TSC1 or TSC2 and consequent dysregulation of signaling via mechanistic Target of Rapamycin Complex 1 (mTORC1). While TSC neurological phenotypes are well-documented, it is not yet known how early in neural development TSC1/2-mutant cells diverge from the typical developmental trajectory, and whether such phenotypes are seen in the heterozygous-mutant populations comprising the vast majority of cells in patient tissues. Using TSC patient-derived isogenic induced pluripotent stem cells (iPSCs), we observed aberrant early neurodevelopment in vitro, including misexpression of key transcription factors associated with lineage commitment and premature electrical activity. These alterations in differentiation were coincident with widespread changes in DNA methylation, including at loci associated with key genes in neurodevelopment. Collectively, these data suggest that mutation or loss of TSC2 affects gene regulation and expression at earlier timepoints than previously appreciated, with implications for whether and how prenatal treatment should be pursued.
2024-06-26 | GSE269086 | GEO