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Tuberous sclerosis complex (TSC) is a rare genetic disease causing multisystem growth of benign tumours and other hamartomatous lesions, which leads to diverse and debilitating clinical symptoms. Patients are born with TSC1 or TSC2 mutations, and somatic inactivation of wild-type alleles drives MTOR activation; however, second hits to TSC1/TSC2 are not always observed. Here, we present the genomic landscape of TSC hamartomas. We determine that TSC lesions contain a low somatic mutational burden relative to carcinomas, a subset feature large-scale chromosomal aberrations, and highly conserved molecular signatures for each type exist. Analysis of the molecular signatures coupled with computational approaches reveals unique aspects of cellular heterogeneity and cell origin. Using immune data sets, we identify significant neuroinflammation in TSC-associated brain tumours. Taken together, this molecular catalogue of TSC serves as a resource into the origin of these hamartomas and provides a framework that unifies genomic and transcriptomic dimensions for complex tumours. Tuberous sclerosis complex (TSC) is a rare genetic disease causing multisystem tumour growth. Here the authors analyse 111 TSC-associated tissues for TSC1/TSC2 status, DNA mutations, copy number aberrations, differential gene expression and DNA methylation patterns providing a comprehensive genomic landscape.

Tuberous sclerosis complex (TSC) integrates upstream stimuli and regulates cell growth by controlling the activity of mTORC1. TSC complex functions as a GTPase-activating protein (GAP) towards small GTPase Rheb and inhibits Rheb-mediated activation of mTORC1. Mutations in TSC genes cause tuberous sclerosis. In this study, the near-atomic resolution structure of human TSC complex reveals an arch-shaped architecture, with a 2:2:1 stoichiometry of TSC1, TSC2, and TBC1D7. This asymmetric complex consists of two interweaved TSC1 coiled-coil and one TBC1D7 that spans over the tail-to-tail TSC2 dimer. The two TSC2 GAP domains are symmetrically cradled within the core module formed by TSC2 dimerization domain and central coiled-coil of TSC1. Structural and biochemical analyses reveal TSC2 GAP-Rheb complimentary interactions and suggest a catalytic mechanism, by which an asparagine thumb (N1643) stabilizes γ-phosphate of GTP and accelerate GTP hydrolysis of Rheb. Our study reveals mechanisms of TSC complex assembly and GAP activity. Tuberous sclerosis complex (TSC) regulates cell growth by controlling the activity of mTORC1. The structure of human TSC complex reveals an arch-shaped, asymmetric architecture and a 2:2:1 stoichiometry of TSC1, TSC2, and TBC1D7 subunits and suggests a mechanism by which TSC2 accelerates GTP hydrolysis against a small GTPase Rheb.

In the EXIST-1 trial, initiated on Aug 10, 2009, more than 35% of patients with subependymal giant cell astrocytoma (SEGA) associated with tuberous sclerosis complex had at least 50% reduction in SEGA volume after 9·6 months of treatment with everolimus. In this Article, we report interim data (up to Jan 11, 2013) to support longer-term tolerability and efficacy of everolimus from the continuing 4-year extension phase of EXIST-1. We assessed data from a prospective, open-label extension of a multicentre, phase 3, randomised, double-blind, placebo-controlled study in patients with tuberous sclerosis complex who had SEGA that was growing and needed treatment. In this extension study, we included all patients who had been assigned everolimus during the double-blind, randomised phase of the trial and those patients who crossed over from the placebo group to receive everolimus during the randomised phase or at the start of the extension phase. All patients received oral everolimus at a starting dose of 4·5 mg/m2 per day. Everolimus dose was subsequently adjusted subject to tolerability to attain blood trough concentrations of 5–15 ng/mL. An independent central radiology review team assessed SEGA response (at least a 50% reduction from baseline in total volume of all target SEGAs; the primary endpoint) by MRI at 12, 24, and 48 weeks, then every year thereafter in all patients who received at least one dose of everolimus. This study was registered with ClinicalTrials.gov, number NCT00789828. Of the original 117 randomly assigned patients, 111 were given everolimus between Aug 20, 2009, and Jan 11, 2013 (date of data cutoff); we included these patients in our longer-term analysis. Median duration of everolimus exposure was 29·3 months (IQR 19·4–33·8). Median follow-up was 28·3 months (IQR 19·3–33·0). 54 (49%) patients had a response of 50% or greater reduction in SEGA volume (95% CI 39·0–58·3), and duration of response was between 2·1 and 31·1 months (median not reached). SEGA volume was reduced by 50% or more in 39 (37%) of 105 patients at 24 weeks, 48 (46%) of 104 patients at 48 weeks, 36 (47%) of 76 patients at 96 weeks, and 11 (38%) of 29 patients at 144 weeks. Stomatitis (48 [43%] patients) and mouth ulceration (33 [30%] patients) were the most frequent treatment-related adverse events; infections were the most commonly reported treatment-related serious adverse event, occurring in 15 (14%) patients. 35 (32%) patients reported treatment-related grade 3 or 4 adverse events, the most common of which were stomatitis (nine [8%]) and pneumonia (nine [8%]). 18 (16%) patients had treatment-related serious adverse events. Six (5%) patients withdrew because of adverse events. These results support the longer-term use of everolimus in patients who have few treatment options and who need continued treatment for tuberous sclerosis complex and its varied manifestations. Reduction or stabilisation of tumour volume with everolimus will hopefully provide long-term clinical benefit in patients with SEGA. Novartis Pharmaceuticals.

The limited and inconsistent efficacy of existing therapies for tuberous sclerosis complex (TSC) has driven the exploration of novel strategies, including epigenetic regulation. GSK-J4, an inducer of global H3K27me3 accumulation, shows broad anti-tumor activity. However, its therapeutic potential in TSC remains unclear. In the study, we reported that GSK-J4 inhibited cell cycle progression and induced apoptosis in primary Tsc1+/− and Tsc2+/− MEFs. Mechanistically, Tsc1 or Tsc2 deletion reduced global H3K27me3, correlating with increased viability, accelerated cell cycle, and suppressed apoptosis-phenotypes reversed by GSK-J4. Moreover, GSK-J4 triggered endoplasmic reticulum stress (ERS) by activating the PERK-ATF4-CHOP axis, which concurrently downregulated the proto-oncogene c-Myc, outlining a GSK-J4→p-PERK→c-Myc inhibitory pathway. Notably, GSK-J4 synergized with rapamycin to enhance cell cycle arrest and apoptosis. In vivo, this combination alleviated renal impairment in Tsc1- or Tsc2-deficient models, suggesting a promising therapeutic strategy for TSC patients with suboptimal response to mammalian target of rapamycin complex 1 (mTORC1) inhibitors. Our study elucidates a specific ERS-dependent anti-tumor mechanism of GSK-J4 in Tsc-deficient contexts and demonstrates the synergistic efficacy of combining epigenetic and mTORC1 inhibitors.

Tuberous sclerosis complex (TSC) is a multisystem developmental disorder caused by mutations in the TSC1 or TSC2 genes, whose protein products are negative regulators of mechanistic target of rapamycin complex 1 signaling. Hallmark pathologies of TSC are cortical tubers—regions of dysmorphic, disorganized neurons and glia in the cortex that are linked to epileptogenesis. To determine the developmental origin of tuber cells, we established human cellular models of TSC by CRISPR–Cas9-mediated gene editing of TSC1 or TSC2 in human pluripotent stem cells (hPSCs). Using heterozygous TSC2 hPSCs with a conditional mutation in the functional allele, we show that mosaic biallelic inactivation during neural progenitor expansion is necessary for the formation of dysplastic cells and increased glia production in three-dimensional cortical spheroids. Our findings provide support for the second-hit model of cortical tuber formation and suggest that variable developmental timing of somatic mutations could contribute to the heterogeneity in the neurological presentation of TSC. CRISPR–Cas9-mediated gene editing of TSC1 and TSC2 in human pluripotent stem cells is used to investigate the contribution of tuberous sclerosis complex–mechanistic target of rapamycin complex 1 signaling to human neural development in two-dimensional monolayer and three-dimensional spheroid models of the neurodevelopmental disorder tuberous sclerosis complex.

Background Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder characterized by multisystem involvement, primarily caused by loss-of-function mutations in the TSC1 or TSC2 genes. TSC is a key integrator of metabolic signaling and cellular stress and has become an important regulator in several kidney diseases. Summary TSC1 and TSC2 can be used not only as genetic markers for disease diagnosis, but also as potential immunotherapeutic targets for kidney disease. Recent studies on the pathogenesis of TSC may provide guidance for developing new treatment strategies for kidney diseases. Key messages Therefore, we systematically reviewed the molecular biology of TSC and their signaling pathway, regulation of cell metabolism, and immune response in acute renal injury, chronic kidney disease, diabetic kidney disease, renal cysts, benign and malignant intrarenal tumors, and renal angiomyolipomas. We also summarize the efficacy and adverse effects of mTOR inhibitors in the treatment of TSC-related kidney diseases.

The TSC complex formed by TSC1 and TSC2 is the most important upstream negative regulator of mTORC1. Genetic variations in either TSC1 or TSC2 cause tuberous sclerosis complex (TSC) disease which is a rare autosomal dominant disorder resulting in impairment of multiple organ systems. In this study, besides a reported variation, c.2509_2512del (p.Asn837Valfs*11, p.N837fs) in TSC1 , we found a de novo TSC2 variation c.1113delG (p.Gln371Hisfs*18, p.Q371fs), which these two mutation influence the formation of TSC complex. We found that the decrease of TSC complex with the appearance of the decreased miR-199b-3p expression. At the same time, the reduction of miR-199b-3p increased the expression of mTOR and the activation of mTORC1 and mTORC2, the additional miR-199b-3p caused the decrease the expression of mTOR and the activation of mTORC1 and mTORC2. In brief, our results may illustrate a novel mechanism of TSC caused by variations in either TSC1 or TSC2 , and a new mTOR expression regulator, miR-199b-3p.

The mechanistic target of rapamycin (mTOR) pathway serves as a master regulator of cell growth, proliferation, and survival. Upregulation of the mTOR pathway has been shown to cause malformations of cortical development, medically refractory epilepsies, and neurodevelopmental disorders, collectively described as mTORopathies. Tuberous sclerosis complex (TSC) serves as the prototypical mTORopathy. Characterized by the development of benign tumors in multiple organs, pathogenic variants in TSC1 or TSC2 disrupt the TSC protein complex, a negative regulator of the mTOR pathway. Variants in critical domains of the TSC complex, especially in the catalytic TSC2 subunit, correlate with increased disease severity. Variants in less crucial exons and non-coding regions, as well as those undetectable with conventional testing, may lead to milder phenotypes. Despite the assumption of complete penetrance, expressivity varies within families, and certain variants delay disease onset with milder neurological effects. Understanding these genotype–phenotype correlations is crucial for effective clinical management. Notably, 15% of patients have no mutation identified by conventional genetic testing, with the majority of cases postulated to be caused by somatic TSC1/TSC2 variants which present complex diagnostic challenges. Advancements in genetic testing, prenatal screening, and precision medicine hold promise for changing the diagnostic and treatment paradigm for TSC and related mTORopathies. Herein, we explore the genetic and molecular mechanisms of TSC and other mTORopathies, emphasizing contemporary genetic methods in understanding and diagnosing the condition.

Background Tuberous sclerosis (TSC)–associated kidney disease is a leading cause of mortality in adults with TSC. This study aimed to understand TSC features in children, particularly kidney involvement, to inform clinical care for this specific group. Methods This retrospective cohort study included all paediatric (< 19 years) TSC cases at a large tertiary paediatric nephrology centre. Relevant data were collected from patients’ records, statistical analyses were performed to identify associations between variables, survival probabilities were estimated with Kaplan‒Meier curves, and log-rank tests were conducted to assess survival differences among genetic mutations. Results A total of 182 children with TSC were included. Among the 145 children with available kidney imaging data, 78.6% (114/145) exhibited kidney lesions. Angiomyolipomas (AMLs) were significantly more prevalent in the TSC2 mutation group ( p  = 0.018). Children with TSC2 mutations generally had poorer lesion-free survival than those with TSC1 mutations, but this difference was only significant for AMLs ( p  = 0.030). The change in size of largest AMLs increased with age and doubled in children above 9 years; a similar pattern was observed when stratified by genetic mutation. In contrast, kidney cysts exhibited two peaks: one in children under 5 years (2.31 mm/year) and the second in children between 15–19 years (2.82 mm/year). Chronic kidney disease was observed in 12.3% (10/81) of children, and high-risk AMLs above 3 cm were observed in 9% (13/145). Conclusions While TSC kidney disease emerges later in the disease course than neurological features, our findings emphasise the importance of kidney surveillance during childhood, including routine kidney imaging, kidney function, and blood pressure monitoring. Graphical abstract A higher resolution version of the Graphical abstract is available as Supplementary information

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder in which renal manifestations are prominent. There are three major renal lesions in TSC: angiomyolipomas, cysts, and renal cell carcinoma (RCC). Major recent advances have revolutionized our understanding of TSC-associated RCC, including two series that together include more than 100 TSC-RCC cases, demonstrating a mean age at onset of about 36 years, tumors in children as young as 7, and a striking 2:1 female predominance. These series also provide the first detailed understanding of the pathologic features of these distinctive tumors, which include chromophobe-like features and eosinophilia, with some of the tumors unclassified. This pathologic heterogeneity is distinctive and reminiscent of the pathologic heterogeneity in Birt–Hogg–Dube-associated RCC, which also includes chromophobe-like tumors. Additional advances include the identification of sporadic counterpart tumors that carry somatic TSC1/TSC2/mTOR mutations. These include unclassified eosinophilic tumors, eosinophilic solid cystic RCC (ESC-RCC), and RCC with leiomyomatous stroma (RCCLMS). A variety of epithelial renal neoplasms have been identified both in patients with tuberous sclerosis complex (TSC) and in the nonsyndromic setting associated with somatic mutations in the TSC1 and TSC2 genes. Interestingly, whether tumors are related to a germline or somatic TSC1/2 mutation, these tumors often display similar morphologic and immunophenotypic features. Finally, recent work has identified molecular links between TSC and BHD-associated tumors, involving the TFEB/TFE3 transcription factors.