Tuberous Sclerosis Complex Disease Research Articles

Neuronal Tsc1/2 complex controls autophagy through AMPK-dependent regulation of ULK1

Tuberous sclerosis complex (TSC) is a disorder arising from mutation in the TSC1 or TSC2 gene, characterized by the development of hamartomas in various organs and neurological manifestations including epilepsy, intellectual disability and autism. TSC1/2 protein complex negatively regulates the mammalian target of rapamycin complex 1 (mTORC1) a master regulator of protein synthesis, cell growth and autophagy. Autophagy is a cellular quality-control process that sequesters cytosolic material in double membrane vesicles called autophagosomes and degrades it in autolysosomes. Previous studies in dividing cells have shown that mTORC1 blocks autophagy through inhibition of Unc-51-like-kinase1/2 (ULK1/2). Despite the fact that autophagy plays critical roles in neuronal homeostasis, little is known on the regulation of autophagy in neurons. Here we show that unlike in non-neuronal cells, Tsc2-deficient neurons have increased autolysosome accumulation and autophagic flux despite mTORC1-dependent inhibition of ULK1. Our data demonstrate that loss of Tsc2 results in autophagic activity via AMPK-dependent activation of ULK1. Thus, in Tsc2-knockdown neurons AMPK activation is the dominant regulator of autophagy. Notably, increased AMPK activity and autophagy activation are also found in the brains of Tsc1-conditional mouse models and in cortical tubers resected from TSC patients. Together, our findings indicate that neuronal Tsc1/2 complex activity is required for the coordinated regulation of autophagy by AMPK. By uncovering the autophagy dysfunction associated with Tsc2 loss in neurons, our work sheds light on a previously uncharacterized cellular mechanism that contributes to altered neuronal homeostasis in TSC disease.

Lymphangioleiomyomatosis: A rare case report

Lymphangioleiomyomatosis (LAM) is a rare disease of unknown etiology that traditionally affects young women of child bearing or premenopausal age. It is characterized by proliferation of atypical smooth muscle cells, preferentially along bronchovascular structures that causes progressive respiratory failure. Due to its unusual and nonspecific presenting symptoms, patients often receive missed or delayed diagnosis. This disease occurs sporadically or in association with the genetic disease tuberous sclerosis complex (TSC). We present 34-year-old young premenopausal woman with LAM.

Tuberous sclerosis complex, mTOR, and the kidney: report of an NIDDK-sponsored workshop

Remarkable basic and translational advances have elucidated the role of the mammalian target of rapamycin (mTOR) signaling network in the pathogenesis of renal disease. Many of these advances originated from studies of the genetic disease tuberous sclerosis complex (TSC), leading to one of the clearest therapeutic opportunities to target mTOR with rapamycin and its analogs ("rapalogs"), which effectively inhibit mTOR complex 1 (mTORC1) by an allosteric mechanism. Clinical trials based on these discoveries have provided strongly positive therapeutic results in TSC (Bissler JJ, McCormack FX, Young LR, Elwing JM, Chuck G, Leonard JM, Schmithorst VJ, Laor T, Brody AS, Bean J, Salisbury S, Franz DN. N Engl J Med 358: 140-151, 2008; Krueger DA, Care MM, Holland K, Agricola K, Tudor C, Mangeshkar P, Wilson KA, Byars A, Sahmoud T, Franz DN. N Engl J Med 363: 1801-1811, 2010; McCormack FX, Inoue Y, Moss J, Singer LG, Strange C, Nakata K, Barker AF, Chapman JT, Brantly ML, Stocks JM, Brown KK, Lynch JP 3rd, Goldberg HJ, Young LR, Kinder BW, Downey GP, Sullivan EJ, Colby TV, McKay RT, Cohen MM, Korbee L, Taveira-DaSilva AM, Lee HS, Krischer JP, Trapnell BC. N Engl J Med 364: 1595-1606, 2011). In June 2013, the National Institute of Diabetes and Digestive and Kidney Diseases convened a small panel of physicians and scientists working in the field to identify key unknowns and define possible "next steps" in advancing understanding of TSC- and mTOR-dependent renal phenotypes. TSC-associated renal disease, which affects >85% of TSC patients, and was a major topic of discussion, focused on angiomyolipomas and epithelial cysts. The third major topic was the role of mTOR and mTOR inhibition in the pathogenesis and therapy of chronic renal disease. Renal cell carcinoma, while recognized as a manifestation of TSC that occurs in a small fraction of patients, was not the primary focus of this workshop and thus was omitted from panel discussions and from this report.

Germline TSC1 mutations are permissive for T lymphocyte development and homeostasis in Tuberous Sclerosis individuals.

Event Abstract Back to Event Germline TSC1 mutations are permissive for T lymphocyte development and homeostasis in Tuberous Sclerosis individuals. Karolina Pilipow1, 2*, Veronica Basso2, Nicola Migone3 and Anna Mondino2 1 Vita-Salute San Raffaele University, Italy 2 San Raffaele Scientific Institute, Italy 3 University of Turin, Department of Genetics, Biology and Biochemistry, Italy Antigen recognition on the surface of antigen presenting cells initiate a variety of intracellular signals critical for naïve T cells to commit to proliferate and differentiate. Others and we have shown the TSC/mTOR axis to be critical in coordinating cell quiescence, proliferation and fate determination. Blocking mTOR by Rapamycin, or genetic inactivation of components of the mTOR Complex (mTORC) or TSC1, unbalances mTORC1 and mTORC2 regulation, impacting on cell quiescence, proliferation and differentiation. In humans, germline mutations of TSC1 predispose to Tuberous Sclerosis Complex disease, an autosomal dominant disorder characterized by multifocal hamartomatosis. Whether such mutations impact on T cell functions in these individuals was unknown. To this aim we analyzed subset representation, phenotype and function of T cells from two independent families with characterized mutations of TSC1 in parallel to T cells from healthy volunteers and to mouse T cells with mono- or bilallelic deletion of Tsc1 (from T-lineage restricted Tsc1+/- and Tsc1-/- mice). We found that heterozygosis of Tsc1/TSC1 is sufficient for proper hamartin expression and both homeostatic and TCR-induced mTORC1 and mTORC2-dependent signaling in mice and human T cells. In contrast, loss of Tsc1/TSC1 following biallelic genetic inactivation and shRNA-induced down-regulation unbalanced mTORC-dependent FOXO1/3 regulation, leading to loss of mitochondrial potential apoptotic cell death. Thus, while heterozygosis of Tsc1/TSC1 is sufficient for proper T lymphocyte development and homeostasis, its more severe loss is incompatible with both mouse and human T cell survival. Acknowledgements The authors wish to thank TSC subjects and their family for support, members of the San Raffaele Scientific Institute for suggestions, Dr Rossella Galli for Tsc1 fl/fl mice, Dr Ruggero Pardi for CD4cre mice and Dr Vincenzo Calautti (Dulbecco Telethon Institute, Molecular Biotechnology Center, University of Turin) for the help with TSC1 shRNA. This work was supported by the Associazione Italiana Ricerca sul Cancro. KP benefited of fellowships from the San Raffaele Vita-Salute University and FIRC. Keywords: T lymphocytes, Intracellular signaling, TSC/mTOR, intrinsic apoptosis, Tuberous Sclerosis Complex Disease Conference: 15th International Congress of Immunology (ICI), Milan, Italy, 22 Aug - 27 Aug, 2013. Presentation Type: Abstract Topic: Adaptive Immunity Citation: Pilipow K, Basso V, Migone N and Mondino A (2013). Germline TSC1 mutations are permissive for T lymphocyte development and homeostasis in Tuberous Sclerosis individuals.. Front. Immunol. Conference Abstract: 15th International Congress of Immunology (ICI). doi: 10.3389/conf.fimmu.2013.02.00976 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Jun 2013; Published Online: 22 Aug 2013. * Correspondence: Dr. Karolina Pilipow, Vita-Salute San Raffaele University, Milan, Italy, kpilipow@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Karolina Pilipow Veronica Basso Nicola Migone Anna Mondino Google Karolina Pilipow Veronica Basso Nicola Migone Anna Mondino Google Scholar Karolina Pilipow Veronica Basso Nicola Migone Anna Mondino PubMed Karolina Pilipow Veronica Basso Nicola Migone Anna Mondino Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Is mTOR inhibition a systemic treatment for tuberous sclerosis?

Tuberous sclerosis complex (TSC) is a genetic multisystem disorder characterized by the development of hamartomas in several organs. Mutations in the TSC1 and TSC2 tumor suppressor genes determin overactivation of the mammalian target of rapamycin (mTOR) signaling pathway and subsequent abnormalities in numerous cell processes. As a result, mTOR inhibitors such as sirolimus and everolimus have the potential to provide targeted therapy for TSC patients. Everolimus has been recently approved as a pharmacotherapy option for TSC patients with subependymal giant-cell astrocytomas (SEGAs) or renal angiomyolipomas (AMLs). However, clinical evidence suggests that this treatment can benefit other TSC-associated disease manifestations, such as skin manifestations, pulmonary lymphangioleiomyomatosis, cardiac rhabdomyomas, and epilepsy. Therefore, the positive effects that mTOR inhibition have on a wide variety of TSC disease manifestations make this a potential systemic treatment option for this genetic multifaceted disorder.

The TSC1-TSC2 complex consists of multiple TSC1 and TSC2 subunits

BackgroundMutations to the TSC1 and TSC2 genes cause the disease tuberous sclerosis complex. The TSC1 and TSC2 gene products form a protein complex that integrates multiple metabolic signals to regulate the activity of the target of rapamycin (TOR) complex 1 (TORC1) and thereby control cell growth. Here we investigate the quaternary structure of the TSC1-TSC2 complex by gel filtration and coimmunoprecipitation.ResultsTSC1 and TSC2 co-eluted in high molecular weight fractions by gel filtration. Coimmunoprecipitation of distinct tagged TSC1 and TSC2 isoforms demonstrated that TSC1-TSC2 complexes contain multiple TSC1 and TSC2 subunits.ConclusionsTSC1 and TSC2 interact to form large complexes containing multiple TSC1 and TSC2 subunits.

Novel mechanism of regulation of the DNA repair enzyme OGG1 in tuberin-deficient cells

Tuberin (protein encodes by tuberous sclerosis complex 2, Tsc2) deficiency is associated with the decrease in the DNA repair enzyme 8-oxoG-DNA glycosylase (OGG1) in tumour kidney of tuberous sclerosis complex (TSC) patients. The purpose of this study was to elucidate the mechanisms by which tuberin regulates OGG1. The partial deficiency in tuberin expression that occurs in the renal proximal tubular cells and kidney cortex of the Eker rat is associated with decreased activator protein 4 (AP4) and OGG1 expression. A complete deficiency in tuberin is associated with loss of AP4 and OGG1 expression in kidney tumour from Eker rats and the accumulation of significant levels of 8-oxo-deoxyguanosine. Knockdown of tuberin expression in human renal epithelial cells (HEK293) with small interfering RNA (siRNA) also resulted in a marked decrease in the expression of AP4 and OGG1. In contrast, overexpression of tuberin in HEK293 cells increased the expression of AP4 and OGG1 proteins. Downregulation of AP4 expression using siRNA resulted in a significant decrease in the protein expression of OGG1. Immunoprecipitation studies show that AP4 is associated with tuberin in cells. Gel shift analysis and chromatin immunoprecipitation identified the transcription factor AP4 as a positive regulator of the OGG1 promoter. AP4 DNA-binding activity is significantly reduced in Tsc2(-/-) as compared with Tsc2(+/+) cells. Transcriptional activity of the OGG1 promoter is also decreased in tuberin-null cells compared with wild-type cells. These data indicate a novel role for tuberin in the regulation of OGG1 through the transcription factor AP4. This regulation may be important in the pathogenesis of kidney tumours in patients with TSC disease.

European Respiratory Society guidelines for the diagnosis and management of lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare lung disease, which occurs sporadically or in association with the genetic disease tuberous sclerosis complex (TSC) 1, 2. Sporadic LAM affects ∼1 in 400,000 adult females; in TSC, LAM occurs in 30–40% of adult females 3, 4 and exceptionally in males and children 5, 6. Patients with LAM usually develop progressive dyspnoea and recurrent pneumothorax, chylous collections and occasional haemoptysis 1. Extra pulmonary lymphadenopathy and cystic masses of the axial lymphatics termed lymphangioleiomyomas can result in abdominal and pelvic lymphatic obstruction 7. LAM is often associated with angiomyolipoma in the kidneys 8, and an increased frequency of meningioma 9. LAM varies in clinical features and rate of progression: this together with an absence of clear prognostic factors results in patients being given conflicting information about prognosis. Diagnosis is made by tissue biopsy (generally from the lung but occasionally from lymph nodes or lymphangioleiomyomas) and/or a combination of history and high-resolution computed tomography scanning (HRCT). Pathological diagnosis relies on characteristic LAM cell morphology and positive immunoreactivity to smooth muscle actin and HMB-45 antibodies. Increasingly HRCT is used to diagnose LAM without resorting to lung biopsy; however a number of conditions with multiple pulmonary cysts can mimic LAM. As LAM is rare, there have been no controlled trials of its management. Supportive treatment includes management of airflow obstruction and hypoxaemia with bronchodilators and oxygen respectively, specific treatment for surgical or pleural complications including pneumo- and chylothorax, and interventional treatment of renal lesions 10, 11. As LAM is a disease of females and is thought to be accelerated by oestrogen, oophorectomy, tamoxifen, progesterone and gonadotropin-releasing hormone (GnRH) analogues have been used without evidence that they are effective. The recent finding of abnormalities in the TSC1/2 genes resulting …

Molecular mechanism of regulation of OGG1: tuberin deficiency results in cytoplasmic redistribution of transcriptional factor NF-YA

The tuberous sclerosis complex (TSC) is caused by defects in one of two tumor suppressor genes, TSC-1 or TSC-2. TSC-2 gene encodes tuberin, a protein involved in the pathogenesis of kidney tumors, both angiomyolipomas and renal cell carcinomas. On the other hand, mice-deficient in the DNA repair enzyme OGG1 spontaneously develop adenoma and carcinoma. Downregulation of tuberin results in a marked decrease of OGG1 and accumulation of oxidative DNA damage, (8-oxodG) in cultured cells. In addition, tuberin haploinsufficiency is associated with the loss of OGG1 and accumulation of 8-oxodG in rat kidney tumor. Deficiency in tuberin results in decreased OGG1 and NF-YA protein expression and increased 8-oxodG in kidney tumor from TSC patients. In the current study, molecular mechanisms by which tuberin regulates OGG1 were explored. The deficiency of tuberin was associated with a significant decrease in NF-YA and loss of OGG1 in kidney tumors of Eker rat. Downregulation of tuberin by siRNA resulted in a marked decrease in NF-YA and OGG1 protein expression in human renal epithelial cells. Localization of NF-YA in wild type and tuberin-deficient cells was examined by western blot and immunostaining assays. In wild type cells, NF-YA was detected in the nucleus while in tuberin deficient cells in the cyotoplasm. Introducing adenovirus-expressing tuberin (Ad-TSC2) into tuberin-deficient cells restored the nuclear localization of NF-YA. These data define a novel mechanism of regulation of OGG1 through tuberin. This mechanism may be important in the pathogenesis of kidney tumors in patients with TSC disease.

Tuberous sclerosis complex: disease modifiers and treatments

Tuberous sclerosis complex (TSC) is an autosomal dominant neurocutaneous disorder involving benign growths in multiple organ systems of affected patients. Variable phenotypes from mild to severe have been reported for related as well as unrelated patients affected by TSC. The two causative genes, TSC1 and TSC2, which code for hamartin and tuberin respectively, play central roles in regulating cell survival and proliferation signaling pathways. The severity of disease phenotypes of TSC patients is influenced by the activities of genes both up and down-stream in the associated pathways. The high-expressing12CA repeat variant of the IFNG gene was suggested to contribute lower risk for kidney angiomyolipomas in patients with TSC2 gene mutations. Genetic modifiers for TSC have been localized on chromosomes 3 and 5 of the rat genome. We performed association studies linking the c.68C allele of the 5-hydroxytryptamine receptor 2C gene to lower seizure risk in TSC-affected individuals. Genetic and epigenetic factors affecting the activity of each and every interacting partner of the tuberin-hamartin complex could potentially alter the disease presentation. Identifying functional polymorphic variants of interacting partners affecting TSC gene functions will delineate the mechanisms leading to TSC disease severity, ultimately resulting in treatment strategies.

Role of TSC–mTOR pathway in diabetic nephropathy

TSC–mTOR signaling plays a crucial role in the regulation of cell growth and survival control. Mammalian target of rapamycin (mTOR) is an evolutionarily conserved serine/threonine kinase that forms two distinct functional complexes, termed TOR complex 1 (TORC1) and TORC2, respectively. TORC1 is a rapamycin-sensitive complex and regulates a wide array of cellular processes including translation, transcription, and autophagy. Tuberous sclerosis complex (TSC) gene products, TSC1 and TSC2 are tumor suppressors and specifically suppress TORC1 activity. Mutation of either TSC1 or TSC2 causes TSC disease, which is characterized by formation of hamartomas in multiple organs. Although the role of TSC–mTOR pathway in tumor and cancer development has been extensively studied, more recent studies have indicated a role for mTOR function in appetite, memory, aging, and energy metabolism. Dysregulation of the TSC–mTOR pathway may cause not only tumor development but also metabolic disorders such as diabetes and its complications.

Tuberous Sclerosis Complex With Polycystic Kidney Disease of the Adult Type: the TSC2/ADPKD1 Contiguous Gene Syndrome

Although different diseases, tuberous sclerosis complex and autosomal dominant polycystic kidney disease have been seen in association, the molecular basis of this being the proximity of tuberous sclerosis complex 2 and polycystic kidney disease 1 genes on the same chromosome (16p13.3). Therefore, the classic autosomal dominant polycystic kidney disease renal phenotype may occur in the context of tuberous sclerosis complex disease as a result of large deletions involving both the polycystic kidney disease 1 and tuberous sclerosis complex 2 genes. This is known as the tuberous sclerosis complex 2/autosomal dominant polycystic kidney disease 1 contiguous gene syndrome. The criteria for this condition are fulfilled when renal lesions typical for classic autosomal dominant polycystic kidney disease phenotype are associated with tuberous sclerosis complex phenotype. We present a new case of the sporadic form of this genetic disorder. The diagnosis of tuberous sclerosis complex in this patient was established on the presence of major and minor features, and the diagnosis of ADPKD was based on the presence of numerous large roundish renal cysts lined by a nondescript tubular epithelium. Sporadic cases of autosomal dominant polycystic kidney disease and tuberous sclerosis complex do occur. Molecular analysis was not performed because the patient's parents refused permission.

Rheb fills a GAP between TSC and TOR

There has been much interest in determining the molecular and cellular functions of hamartin and tuberin, which are encoded by the genes TSC1 and TSC2 that are mutated in the tuberous sclerosis complex disease. Recently, several laboratories have independently reported a major breakthrough in this field. Together, these genetic, biochemical and cell-biological studies have demonstrated that the tuberin–hamartin complex inhibits target of rapamycin (TOR) signaling by acting as a GTPase-activating protein for the Ras-related small G protein Rheb.

United at last: the tuberous sclerosis complex gene products connect the phosphoinositide 3-kinase/Akt pathway to mammalian target of rapamycin (mTOR) signalling.

The molecular interplay between the phosphoinositide 3-kinase (PI3K) pathway and mammalian target of rapamycin (mTOR) signalling in the control of cell growth and proliferation has been the subject of much interest and debate amongst cell biologists. A recent escalation of research in this area has come from the discovery of the tuberous sclerosis complex gene products, tuberin and hamartin, as central regulators of mTOR activation. The PI3K effector Akt/protein kinase B has been found to directly phosphorylate tuberin and is thereby thought to activate mTOR through inhibition of the tuberin-hamartin complex. The many recent studies aimed at defining the molecular nature of this revamped PI3K/Akt/mTOR pathway are reviewed here. The collective data discussed have laid the groundwork for important new insights into the many cancers caused by aberrant PI3K activation and the clinically challenging tuberous sclerosis complex disease and have suggested a possible means of treatment for both.

Carotid artery aneurysm in a child with tuberous sclerosis

Tuberous sclerosis complex (TSC) is an autosomal dominant disease of variable penetrance characterised by the presence and growth of hamar tomas in almost every organ. Dysplasia and hamar tomatous proliferation of small blood vessels including haemangiomas are commonplace in TSC but intrinsic disease of medium-sized and large vessels is rare and often fatal. 1 To our knowledge this is the first reported case of carotid ar tery aneurysm in a patient with tuberous sclerosis.