TSC2

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 12006 Experts worldwide ranked by ideXlab platform

David J Kwiatkowski - One of the best experts on this subject based on the ideXlab platform.

  • TSC2 regulates microrna biogenesis via mtorc1 and gsk3β
    Human Molecular Genetics, 2018
    Co-Authors: Barbara Ogorek, David J Kwiatkowski, Damir Khabibullin, Julie Nijmeh, Robinson Triboulet, Richard I Gregory, Elizabeth P. Henske
    Abstract:

    : Tuberous sclerosis complex (TSC) is an autosomal dominant disease caused by germline inactivating mutations of TSC1 or TSC2. In TSC-associated tumors of the brain, heart, skin, kidney and lung, inactivation of both alleles of TSC1 or TSC2 leads to hyperactivation of the mTORC1 pathway. The TSC/mTORC1 pathway is a key regulator of cellular processes related to growth, proliferation and autophagy. We and others have previously found that mTORC1 regulates microRNA biogenesis, but the mechanisms are not fully understood. Microprocessor, a multi-protein complex including the nuclease Drosha, processes the primary miR transcript. Using a dual-luciferase reporter, we found that inhibition of mTORC1 or downregulation of Raptor decreased Microprocessor activity, while loss of TSC2 led to a striking increase (∼5-fold) in Microprocessor activity. To determine the global impact of TSC2 on microRNAs we quantitatively analyzed 752 microRNAs in TSC2-expressing and TSC2-deficient cells. Out of 259 microRNAs expressed in both cell lines, 137 were significantly upregulated and 24 were significantly downregulated in TSC2-deficient cells, consistent with the increased Microprocessor activity. Microprocessor activity is known to be regulated in part by GSK3β. We found that total GSK3β levels were higher in TSC2-deficient cells, and the increase in Microprocessor activity associated with TSC2 loss was reversed by three different GSK3β inhibitors. Furthermore, mTOR inhibition increased the levels of phospho-GSK3β (S9), which negatively affects Microprocessor activity. Taken together these data reveal that TSC2 regulates microRNA biogenesis and Microprocessor activity via GSK3β.

  • mutations in tsc1 TSC2 and mtor are associated with response to rapalogs in patients with metastatic renal cell carcinoma
    Clinical Cancer Research, 2016
    Co-Authors: David J Kwiatkowski, Magdalena E Tyburczy, Toni K Choueiri, Brian I Rini, Aaron R Thorner, Guillermo De Velasco, Lana Hamieh, Laurence Albiges, Neeraj Agarwal, Thai H Ho
    Abstract:

    Purpose: We examined the hypothesis that mutations in mTOR pathway genes are associated with response to rapalogs in metastatic renal cell carcinoma (mRCC). Experimental Design: We studied a cohort of mRCC patients who were treated with mTOR inhibitors with distinct clinical outcomes. Tumor DNA from 79 subjects was successfully analyzed for mutations using targeted next-generation sequencing of 560 cancer genes. Responders were defined as those with partial response (PR) by RECIST v1.0 or stable disease with any tumor shrinkage for 6 months or longer. Nonresponders were defined as those with disease progression during the first 3 months of therapy. Fisher exact test assessed the association between mutation status in mTOR pathway genes and treatment response. Results: Mutations in MTOR, TSC1 , or TSC2 were more common in responders, 12 (28%) of 43, than nonresponders, 4 (11%) of 36 ( P = 0.06). Mutations in TSC1 or TSC2 alone were also more common in responders, 9 (21%), than nonresponders, 2(6%), ( P = 0.05). Furthermore, 5 (42%) of 12 subjects with PR had mutations in MTOR, TSC1 , or TSC2 compared with 4 (11%) of 36 nonresponders ( P = 0.03). Eight additional non-mTOR pathway genes were found to be mutated in at least 4 of 79 tumors (5%); none were associated positively with response. Conclusions: In this cohort of mRCC patients, mutations in MTOR, TSC1 , or TSC2 were more common in patients who experienced clinical benefit from rapalogs than in those who progressed. However, a substantial fraction of responders (24 of 43, 56%) had no mTOR pathway mutation identified. Clin Cancer Res; 22(10); 2445–52. ©2016 AACR . See related commentary by Voss and Hsieh, [p. 2320][1] [1]: /lookup/volpage/22/2320?iss=10

  • tbc1d7 is a third subunit of the tsc1 TSC2 complex upstream of mtorc1
    Molecular Cell, 2012
    Co-Authors: Christian C Dibble, Winfried Elis, Suchithra Menon, Justin Klekota, John M Asara, Peter Finan, David J Kwiatkowski, Leon O Murphy
    Abstract:

    The tuberous sclerosis complex (TSC) tumor suppressors form the TSC1-TSC2 complex, which limits cell growth in response to poor growth conditions. Through its GTPase-activating protein (GAP) activity toward Rheb, this complex inhibits the mechanistic target of rapamycin (mTOR) complex 1 (mTORC1), a key promoter of cell growth. Here, we identify and biochemically characterize TBC1D7 as a stably associated and ubiquitous third core subunit of the TSC1-TSC2 complex. We demonstrate that the TSC1-TSC2-TBC1D7 (TSC-TBC) complex is the functional complex that senses specific cellular growth conditions and possesses Rheb-GAP activity. Sequencing analyses of samples from TSC patients suggest that TBC1D7 is unlikely to represent TSC3. TBC1D7 knockdown decreases the association of TSC1 and TSC2 leading to decreased Rheb-GAP activity, without effects on the localization of TSC2 to the lysosome. Like the other TSC-TBC components, TBC1D7 knockdown results in increased mTORC1 signaling, delayed induction of autophagy, and enhanced cell growth under poor growth conditions.

  • angiomyolipoma have common mutations in TSC2 but no other common genetic events
    PLOS ONE, 2011
    Co-Authors: Vineeta Bajaj, Izabela A Malinowska, Chinlee Wu, Xin Lu, Laura E Macconaill, David J Kwiatkowski
    Abstract:

    Renal angiomyolipoma are part of the PEComa family of neoplasms, and occur both in association with Tuberous Sclerosis Complex (TSC) and independent of that disorder. Previous studies on the molecular genetic alterations that occur in angiomyolipoma are very limited. We evaluated 9 angiomyolipoma for which frozen tissue was available from a consecutive surgical series. Seven of 8 samples subjected to RT-PCR-cDNA sequencing showed mutations in TSC2; none showed mutations in TSC1 or RHEB. Six of the seven mutations were deletions. We searched for 983 activating and inactivating mutations in 115 genes, and found none in these tumors. Similarly analysis for genomic regions of loss or gain, assessed by Affymetrix SNP6.0 analysis, showed no abnormalities. Loss of heterozygosity in the TSC2 region was commonly seen, except in patients with low frequency TSC2 mutations. We conclude that sporadic renal angiomyolipoma usually have mutations in TSC2, but not TSC1 or RHEB, and have no other common genomic events, among those we searched for. However, chromosomal translocations and gene fusion events were not assessed here. TSC2 inactivation by mutation is a consistent and likely necessary genetic event in the pathogenesis of most angiomyolipoma.

  • analysis of tsc cortical tubers by deep sequencing of tsc1 TSC2 and kras demonstrates that small second hit mutations in these genes are rare events
    Brain Pathology, 2010
    Co-Authors: Jennifer A Chan, David Neal Franz, Harry V Vinters, Gary W Mathern, Bruce E Taillon, Pascal Bouffard, David J Kwiatkowski
    Abstract:

    : Tuberous sclerosis complex (TSC) is an often severe neurocutaneous syndrome. Cortical tubers are the predominant neuropathological finding in TSC, and their number and location has been shown to correlate roughly with the severity of neurologic features in TSC. Past studies have shown that genomic deletion events in TSC1 or TSC2 are very rare in tubers, and suggested the potential involvement of the MAPK pathway in their pathogenesis. We used deep sequencing to assess all coding exons of TSC1 and TSC2, and the activating mutation hot spots within KRAS in 46 tubers from TSC patients. Germline heterozygous mutations were identified in 81% of tubers. The same secondary mutation in TSC2 was identified in six tuber samples from one individual. Further study showed that this second hit mutation was widely distributed in the cortex from one cerebral hemisphere of this individual at frequencies up to 10%. No other secondary mutations were found in the other 40 tubers analyzed. These data indicate that small second hit mutations in any of these three genes are very rare in TSC tubers. However, in one TSC individual, a second hit TSC2 point mutation occurred early during brain development, and likely contributed to tuber formation.

Kun-liang Guan - One of the best experts on this subject based on the ideXlab platform.

  • Regulation of TS1/TSC2 Stability and Rheb GTP Level by Herc1
    2020
    Co-Authors: Kun-liang Guan
    Abstract:

    Abstract : Over the past decade, considerable progress has been made in understanding the molecular genetics of Tuberous Sclerosis (TSC), highlighted by the identification of the two tumor suppressor genes tsc1 and TSC2. Mutations in either tsc1 or TSC2 cause the disease TSC. A surge of recent research from several labs has shown that TSC1/2 antagonizes the mTOR (mammalian target of rapamycin) signaling network, which plays a central role in the regulation of cell growth in response to growth factors, cellular energy, and nutrient levels. In TSC1 or TSC2 mutant cells, the mTOR signaling pathway, as determined by the phosphorylation of S6K (ribosomal S6 kinase) and 4EBP1 (eukaryote initiation factor 4E binding protein), is highly elevated. Recent studies have also shown that TSC2 functions as a GTPase activating protein (GAP) to stimulate GTP hydrolysis of Rheb (a Ras family GTPase), therefore, inactivating Rheb. Both genetic and biochemical studies support that Rheb is a key direct downstream target of TSC2 and plays an essential role to mediate the physiological functions of TSC1/TSC2. The main objective of this project is to investigate the function of Herc in the regulation of TSC1/TSC2 stability and Rheb GTP level.

  • Measurements of TSC2 GAP activity toward Rheb.
    Methods in Enzymology, 2020
    Co-Authors: Yong Li, Ken Inoki, Haris G. Vikis, Kun-liang Guan
    Abstract:

    Tuberous sclerosis complex (TSC) is a genetic disease caused by mutation in either the tsc1 or TSC2 tumor suppressor genes. TSC1 and TSC2 protein form a physical and functional complex in vivo. Recent studies have demonstrated that TSC2 displays GTPase activating protein (GAP) activity specifically toward the small G protein Rheb (Ras homolog enriched in brain) and inhibits its ability to stimulate the mammalian target of rapamycin (mTOR) signaling pathway. We have presented three methods to determine the activity of TSC2 as a GAP toward the Rheb GTPase. The first involves the isolation of TSC2 from cells and measurement of its activity toward Rheb substrate in vitro. The second involves the measurement of Rheb-associated guanine nucleotides as measure of TSC2 GAP activity on Rheb in vivo. The last method is to determine the phosphorylation of S6K1 (ribosomal S6 kinase), which is a downstream target of mTOR, as an indirect assay for TSC2 GAP activity in vivo.

  • the tsc1 and TSC2 tumor suppressors are required for proper er stress response and protect cells from er stress induced apoptosis
    Cell Death & Differentiation, 2011
    Co-Authors: M K Lu, Young Jun Kang, Kun-liang Guan
    Abstract:

    Tuberous sclerosis complex (TSC)1 and TSC2 are tumor suppressors that inhibit cell growth and mutation of either gene causes benign tumors in multiple tissues. The TSC1 and TSC2 gene products form a functional complex that has GTPase-activating protein (GAP) activity toward Ras homolog enriched in brain (Rheb) to inhibit mammalian target of rapamycin complex 1 (mTORC1), which is constitutively activated in TSC mutant tumors. We found that cells with mutation in either TSC1 or TSC2 are hypersensitive to endoplasmic reticulum (ER) stress and undergo apoptosis. Although the TSC mutant cells show elevated eIF2α phosphorylation, an early ER stress response marker, at both basal and induced conditions, induction of other ER stress response markers, including ATF4, ATF6 and C/EBP homologous protein (CHOP), is severely compromised. The defects in ER stress response are restored by raptor knockdown but not by rapamycin treatment in the TSC mutant cells, indicating that a rapamycin-insensitive mTORC function is responsible for the defects in ER stress response. Consistently, activation of Rheb sensitizes cells to ER stress. Our data show an important role of TSC1/TSC2 and Rheb in unfolded protein response and cell survival. We speculate that an important physiological function of the TSC1/2 tumor suppressors is to protect cells from harmful conditions. These observations indicate a potential therapeutic application of using ER stress agents to selectively kill TSC1 or TSC2 mutant cells for TSC treatment.

  • tsc1 stabilizes TSC2 by inhibiting the interaction between TSC2 and the herc1 ubiquitin ligase
    Journal of Biological Chemistry, 2006
    Co-Authors: Huira Chongkopera, Ken Inoki, Yong Li, Francesc R Garciagonzalo, Jose Luis Rosa, Kun-liang Guan
    Abstract:

    Abstract Tuberous sclerosis complex (TSC) is an autosomal dominant disease characterized by hamartoma formation in various organs. Two genes responsible for the disease, TSC1 and TSC2, have been identified. The TSC1 and TSC2 proteins, also called hamartin and tuberin, respectively, have been shown to regulate cell growth through inhibition of the mammalian target of rapamycin pathway. TSC1 is known to stabilize TSC2 by forming a complex with TSC2, which is a GTPase-activating protein for the Rheb small GTPase. We have identified HERC1 as a TSC2-interacting protein. HERC1 is a 532-kDa protein with an E3 ubiquitin ligase homology to E6AP carboxyl terminus (HECT) domain. We observed that the interaction of TSC1 with TSC2 appears to exclude TSC2 from interacting with HERC1. Disease mutations in TSC2, which result in its destabilization, allow binding to HERC1 in the presence of TSC1. Our study reveals a potential molecular mechanism of how TSC1 stabilizes TSC2 by excluding the HERC1 ubiquitin ligase from the TSC2 complex. Furthermore, these data reveal a possible biochemical basis of how certain disease mutations inactivate TSC2.

  • identification of fip200 interaction with the tsc1 TSC2 complex and its role in regulation of cell size control
    Journal of Cell Biology, 2005
    Co-Authors: Zara K Melkoumian, Kun-liang Guan, Xiaoyang Wu, Junlin Guan
    Abstract:

    FIP200 (focal adhesion kinase [FAK] family interacting protein of 200 kD) is a newly identified protein that binds to the kinase domain of FAK and inhibits its kinase activity and associated cellular functions. Here, we identify an interaction between FIP200 and the TSC1TSC2 complex through FIP200 binding to TSC1. We found that association of FIP200 with the TSC1TSC2 complex correlated with its ability to increase cell size and up-regulate S6 kinase phosphorylation but was not involved in the regulation of cell cycle progression. Conversely, knockdown of endogenous FIP200 by RNA interference reduced S6 kinase phosphorylation and cell size, which required TSC1 but was independent of FAK. Furthermore, overexpression of FIP200 reduced TSC1TSC2 complex formation, although knockdown of endogenous FIP200 by RNA interference did not affect TSC1TSC2 complex formation. Lastly, we showed that FIP200 is important in nutrient stimulation-induced, but not energy- or serum-induced, S6 kinase activation. Together, these results suggest a cellular function of FIP200 in the regulation of cell size by interaction with the TSC1TSC2 complex.

Brendan D. Manning - One of the best experts on this subject based on the ideXlab platform.

  • The TSC1–TSC2 Complex: A Key Signal-Integrating Node Upstream of TOR
    The Enzymes, 2020
    Co-Authors: Christian C Dibble, Brendan D. Manning
    Abstract:

    Publisher Summary The complexity and breadth of the signaling network upstream of the TSC1 (hamartin)–TSC2 (tuberin) complex is a testament to the importance of proper regulation of mTORC1 in the tight control over cellular growth and proliferation. The TSC1TSC2 complex negatively regulates TORC1 through its guanosine triphosphatase (GTPase)-activating protein (GAP) activity toward the small G-protein Ras homolog enriched in brain (Rheb), an essential activator of TORC1. In contrast, TORC2 in mammalian cells is positively regulated by the TSC1TSC2 complex through both Rheb and TORC1-dependent and independent mechanisms. The regulatory relationship between the TSC1TSC2 complex and TORC1 appears to be conserved in most eukaryotes, including species of yeast. Multisite phosphorylation of both TSC1 and TSC2 promotes or inhibits the ability of the complex to inhibit Rheb downstream of a wide variety of kinases and signaling pathways. Several of these pathways include important oncogene products and tumor suppressors that can promote inhibition of the TSC1TSC2 complex and contribute to the aberrantly elevated levels of mTORC1 signaling detected in the majority of human cancers. Inactivating mutations in the TSC1 and TSC2 genes give rise to a multifaceted tumor syndrome known as “tuberous sclerosis complex.”

  • insulin stimulates adipogenesis through the akt TSC2 mtorc1 pathway
    PLOS ONE, 2009
    Co-Authors: Hui H Zhang, Jingxiang Huang, Chinlee Wu, Katrin Duvel, Bernard Boback, Shulin Wu, Rachel M Squillace, Brendan D. Manning
    Abstract:

    Background The signaling pathways imposing hormonal control over adipocyte differentiation are poorly understood. While insulin and Akt signaling have been found previously to be essential for adipogenesis, the relative importance of their many downstream branches have not been defined. One direct substrate that is inhibited by Akt-mediated phosphorylation is the tuberous sclerosis complex 2 (TSC2) protein, which associates with TSC1 and acts as a critical negative regulator of the mammalian target of rapamycin (mTOR) complex 1 (mTORC1). Loss of function of the TSC1-TSC2 complex results in constitutive mTORC1 signaling and, through mTORC1-dependent feedback mechanisms and loss of mTORC2 activity, leads to a concomitant block of Akt signaling to its other downstream targets. Methodology/Principal Findings We find that, despite severe insulin resistance and the absence of Akt signaling, TSC2-deficient mouse embryo fibroblasts and 3T3-L1 pre-adipocytes display enhanced adipocyte differentiation that is dependent on the elevated mTORC1 activity in these cells. Activation of mTORC1 causes a robust increase in the mRNA and protein expression of peroxisome proliferator-activated receptor gamma (PPARγ), which is the master transcriptional regulator of adipocyte differentiation. In examining the requirements for different Akt-mediated phosphorylation sites on TSC2, we find that only TSC2 mutants lacking all five previously identified Akt sites fully block insulin-stimulated mTORC1 signaling in reconstituted TSC2 null cells, and this mutant also inhibits adipogenesis. Finally, renal angiomyolipomas from patients with tuberous sclerosis complex contain both adipose and smooth muscle-like components with activated mTORC1 signaling and elevated PPARγ expression. Conclusions/Significance This study demonstrates that activation of mTORC1 signaling is a critical step in adipocyte differentiation and identifies TSC2 as a primary target of Akt driving this process. Therefore, the TSC1-TSC2 complex regulates the differentiation of mesenchymal cell lineages, at least in part, through its control of mTORC1 activity and PPARγ expression.

  • a complex interplay between akt TSC2 and the two mtor complexes
    Biochemical Society Transactions, 2009
    Co-Authors: Jingxiang Huang, Brendan D. Manning
    Abstract:

    Akt/PKB (protein kinase B) both regulates and is regulated by the TSC (tuberous sclerosis complex) 1–TSC2 complex. Downstream of PI3K (phosphoinositide 3-kinase), Akt phosphorylates TSC2 directly on multiple sites. Although the molecular mechanism is not well understood, these phosphorylation events relieve the inhibitory effects of the TSC1TSC2 complex on Rheb and mTORC1 [mTOR (mammalian target of rapamycin) complex] 1, thereby activating mTORC1 in response to growth factors. Through negative-feedback mechanisms, mTORC1 activity inhibits growth factor stimulation of PI3K. This is particularly evident in cells and tumours lacking the TSC1TSC2 complex, where Akt signalling is severely attenuated due, at least in part, to constitutive activation of mTORC1. An additional level of complexity in the relationship between Akt and the TSC1TSC2 complex has recently been uncovered. The growth-factor-stimulated kinase activity of mTORC2 [also known as the mTOR–rictor (rapamycin-insensitive companion of mTOR) complex], which normally enhances Akt signalling by phosphorylating its hydrophobic motif (Ser 473 ), was found to be defective in cells lacking the TSC1TSC2 complex. This effect on mTORC2 can be separated from the inhibitory effects of the TSC1TSC2 complex on Rheb and mTORC1. The present review discusses our current understanding of the increasingly complex functional interactions between Akt, the TSC1TSC2 complex and mTOR, which are fundamentally important players in a large variety of human diseases.

  • the tsc1 TSC2 complex a molecular switchboard controlling cell growth
    Biochemical Journal, 2008
    Co-Authors: Jingxiang Huang, Brendan D. Manning
    Abstract:

    TSC1 and TSC2 are the tumour-suppressor genes mutated in the tumour syndrome TSC (tuberous sclerosis complex). Their gene products form a complex that has become the focus of many signal transduction researchers. The TSC1TSC2 (hamartin–tuberin) complex, through its GAP (GTPaseactivating protein) activity towards the small G-protein Rheb (Ras homologue enriched in brain), is a critical negative regulator of mTORC1 (mammalian target of rapamycin complex 1). As mTORC1 activity controls anabolic processes to promote cell growth, it is exquisitely sensitive to alterations in cell growth conditions. Through numerous phosphorylation events, the TSC1TSC2 complex has emerged as the sensor and integrator of these growth conditions, relaying signals from diverse cellular pathways to properly modulate mTORC1 activity. In the present review we focus on the molecular details of TSC1TSC2 complex regulation and function as it relates to the control of Rheb and mTORCl.

  • regulation of mtor function in response to hypoxia by redd1 and the tsc1 TSC2 tumor suppressor complex
    Genes & Development, 2004
    Co-Authors: James Brugarolas, Brendan D. Manning, Rebecca L Hurley, Jan H Reiling, Ernst Hafen, Lee A Witters, Leif W Ellisen, William G Kaelin
    Abstract:

    Mammalian target of rapamycin (mTOR) is a central regulator of protein synthesis whose activity is modulated by a variety of signals. Energy depletion and hypoxia result in mTOR inhibition. While energy depletion inhibits mTOR through a process involving the activation of AMP-activated protein kinase (AMPK) by LKB1 and subsequent phosphorylation of TSC2, the mechanism of mTOR inhibition by hypoxia is not known. Here we show that mTOR inhibition by hypoxia requires the TSC1/TSC2 tumor suppressor complex and the hypoxia-inducible gene REDD1/RTP801. Disruption of the TSC1/TSC2 complex through loss of TSC1 or TSC2 blocks the effects of hypoxia on mTOR, as measured by changes in the mTOR targets S6K and 4E-BP1, and results in abnormal accumulation of Hypoxia-inducible factor (HIF). In contrast to energy depletion, mTOR inhibition by hypoxia does not require AMPK or LKB1. Down-regulation of mTOR activity by hypoxia requires de novo mRNA synthesis and correlates with increased expression of the hypoxia-inducible REDD1 gene. Disruption of REDD1 abrogates the hypoxia-induced inhibition of mTOR, and REDD1 overexpression is sufficient to down-regulate S6K phosphorylation in a TSC1/TSC2-dependent manner. Inhibition of mTOR function by hypoxia is likely to be important for tumor suppression as TSC2-deficient cells maintain abnormally high levels of cell proliferation under hypoxia.

Mark Nellist - One of the best experts on this subject based on the ideXlab platform.

  • targeted next generation sequencing reveals previously unidentified tsc1 and TSC2 mutations
    BMC Medical Genetics, 2015
    Co-Authors: Mark Nellist, Marianne Hoogeveenwesterveld, Rutger W W Brouwer, Christel E M Kockx, Monique Van Veghelplandsoen, Caroline Withagenhermans, Lida Prinsbakker, Alan Mrsic, Mike M P Van Den Berg, Anna E Koopmans
    Abstract:

    Background Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in TSC1 and TSC2. Conventional DNA diagnostic screens identify a TSC1 or TSC2 mutation in 75 - 90% of individuals categorised with definite TSC. The remaining individuals either have a mutation that is undetectable using conventional methods, or possibly a mutation in another as yet unidentified gene.

  • Identification of regions critical for the integrity of the TSC1-TSC2-TBC1D7 complex.
    PLOS ONE, 2014
    Co-Authors: Arthur Jorge Santiago Lima, Ans M. W. Van Den Ouweland, Dicky J. J. Halley, Marianne Hoogeveen-westerveld, Anneke Maat-kievit, Akio Nakashima, Ushio Kikkawa, Mark Nellist
    Abstract:

    The TSC1-TSC2-TBC1D7 complex is an important negative regulator of the mechanistic target of rapamycin complex 1 that controls cell growth in response to environmental cues. Inactivating TSC1 and TSC2 mutations cause tuberous sclerosis complex (TSC), an autosomal dominant disorder characterised by the occurrence of benign tumours in various organs and tissues, notably the brain, skin and kidneys. TBC1D7 mutations have not been reported in TSC patients but homozygous inactivation of TBC1D7 causes megaencephaly and intellectual disability. Here, using an exon-specific deletion strategy, we demonstrate that some regions of TSC1 are not necessary for the core function of the TSC1-TSC2 complex. Furthermore, we show that the TBC1D7 binding site is encoded by TSC1 exon 22 and identify amino acid residues involved in the TSC1-TBC1D7 interaction.

  • The TSC1-TSC2 complex consists of multiple TSC1 and TSC2 subunits
    BMC Biochemistry, 2012
    Co-Authors: Marianne Hoogeveen-westerveld, Ans M. W. Van Den Ouweland, Dicky J. J. Halley, Leontine Van Unen, André T. Hoogeveen, Mark Nellist
    Abstract:

    Background Mutations 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.

  • A reliable cell-based assay for testing unclassified TSC2 gene variants
    European Journal of Human Genetics, 2008
    Co-Authors: Ricardo Coevoets, Ans M. W. Van Den Ouweland, Dicky J. J. Halley, Sermin Arican, Marianne Hoogeveen-westerveld, Erik J. Simons, Mark Nellist
    Abstract:

    Tuberous sclerosis complex (TSC) is characterised by seizures, mental retardation and the development of hamartomas in a variety of organs and tissues. The disease is caused by mutations in either the TSC1 gene or the TSC2 gene. The TSC1 and TSC2 gene products, TSC1 and TSC2, form a protein complex that inhibits signal transduction to the downstream effectors of the mammalian target of rapamycin (mTOR). We have developed a straightforward, semiautomated in-cell western (ICW) assay to investigate the effects of amino acid changes on the TSC1TSC2-dependent inhibition of mTOR activity. Using this assay, we have characterised 20 TSC2 variants identified in individuals with TSC or suspected of having the disease. In 12 cases, we concluded that the identified variant was pathogenic. The ICW is a rapid, reproducible assay, which can be applied to the characterisation of the effects of novel TSC2 variants on the activity of the TSC1TSC2 complex.

  • Functional characterisation of the TSC1–TSC2 complex to assess multiple TSC2 variants identified in single families affected by tuberous sclerosis complex
    BMC Medical Genetics, 2008
    Co-Authors: Mark Nellist, Ans M. W. Van Den Ouweland, Őzgür Sancak, Miriam Goedbloed, Alwin Adriaans, Marja W. Wessels, Anneke Maat-kievit, Marieke Jh Baars, Charlotte J. Dommering, Dicky J. J. Halley
    Abstract:

    Background Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterised by seizures, mental retardation and the development of hamartomas in a variety of organs and tissues. The disease is caused by mutations in either the TSC1 gene on chromosome 9q34, or the TSC2 gene on chromosome 16p13.3. The TSC1 and TSC2 gene products, TSC1 and TSC2, interact to form a protein complex that inhibits signal transduction to the downstream effectors of the mammalian target of rapamycin (mTOR).

Dicky J. J. Halley - One of the best experts on this subject based on the ideXlab platform.

  • Identification of regions critical for the integrity of the TSC1-TSC2-TBC1D7 complex.
    PLOS ONE, 2014
    Co-Authors: Arthur Jorge Santiago Lima, Ans M. W. Van Den Ouweland, Dicky J. J. Halley, Marianne Hoogeveen-westerveld, Anneke Maat-kievit, Akio Nakashima, Ushio Kikkawa, Mark Nellist
    Abstract:

    The TSC1-TSC2-TBC1D7 complex is an important negative regulator of the mechanistic target of rapamycin complex 1 that controls cell growth in response to environmental cues. Inactivating TSC1 and TSC2 mutations cause tuberous sclerosis complex (TSC), an autosomal dominant disorder characterised by the occurrence of benign tumours in various organs and tissues, notably the brain, skin and kidneys. TBC1D7 mutations have not been reported in TSC patients but homozygous inactivation of TBC1D7 causes megaencephaly and intellectual disability. Here, using an exon-specific deletion strategy, we demonstrate that some regions of TSC1 are not necessary for the core function of the TSC1-TSC2 complex. Furthermore, we show that the TBC1D7 binding site is encoded by TSC1 exon 22 and identify amino acid residues involved in the TSC1-TBC1D7 interaction.

  • The TSC1-TSC2 complex consists of multiple TSC1 and TSC2 subunits
    BMC Biochemistry, 2012
    Co-Authors: Marianne Hoogeveen-westerveld, Ans M. W. Van Den Ouweland, Dicky J. J. Halley, Leontine Van Unen, André T. Hoogeveen, Mark Nellist
    Abstract:

    Background Mutations 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.

  • A reliable cell-based assay for testing unclassified TSC2 gene variants
    European Journal of Human Genetics, 2008
    Co-Authors: Ricardo Coevoets, Ans M. W. Van Den Ouweland, Dicky J. J. Halley, Sermin Arican, Marianne Hoogeveen-westerveld, Erik J. Simons, Mark Nellist
    Abstract:

    Tuberous sclerosis complex (TSC) is characterised by seizures, mental retardation and the development of hamartomas in a variety of organs and tissues. The disease is caused by mutations in either the TSC1 gene or the TSC2 gene. The TSC1 and TSC2 gene products, TSC1 and TSC2, form a protein complex that inhibits signal transduction to the downstream effectors of the mammalian target of rapamycin (mTOR). We have developed a straightforward, semiautomated in-cell western (ICW) assay to investigate the effects of amino acid changes on the TSC1TSC2-dependent inhibition of mTOR activity. Using this assay, we have characterised 20 TSC2 variants identified in individuals with TSC or suspected of having the disease. In 12 cases, we concluded that the identified variant was pathogenic. The ICW is a rapid, reproducible assay, which can be applied to the characterisation of the effects of novel TSC2 variants on the activity of the TSC1TSC2 complex.

  • Functional characterisation of the TSC1–TSC2 complex to assess multiple TSC2 variants identified in single families affected by tuberous sclerosis complex
    BMC Medical Genetics, 2008
    Co-Authors: Mark Nellist, Ans M. W. Van Den Ouweland, Őzgür Sancak, Miriam Goedbloed, Alwin Adriaans, Marja W. Wessels, Anneke Maat-kievit, Marieke Jh Baars, Charlotte J. Dommering, Dicky J. J. Halley
    Abstract:

    Background Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterised by seizures, mental retardation and the development of hamartomas in a variety of organs and tissues. The disease is caused by mutations in either the TSC1 gene on chromosome 9q34, or the TSC2 gene on chromosome 16p13.3. The TSC1 and TSC2 gene products, TSC1 and TSC2, interact to form a protein complex that inhibits signal transduction to the downstream effectors of the mammalian target of rapamycin (mTOR).

  • Phosphorylation and binding partner analysis of the TSC1–TSC2 complex
    Biochemical and Biophysical Research Communications, 2005
    Co-Authors: Mark Nellist, Peter C. Burgers, Ans M. W. Van Den Ouweland, Dicky J. J. Halley, Theo M. Luider
    Abstract:

    Tuberous sclerosis complex (TSC) is an autosomal dominant benign tumour syndrome caused by mutations to either the TSC1 or TSC2 tumour suppressor gene. The TSC1 and TSC2 gene products, TSC1 and TSC2, form a protein complex that integrates inputs from multiple signalling cascades to inactivate the small GTPase rheb, and thereby inhibit mTOR-dependent cell growth. We have used matrix-assisted laser desorption/ionisation time-of-flight and Fourier transform mass spectrometry to identify TSC1 and TSC2 phosphorylation sites and candidate TSC1 and TSC2 interacting proteins. We identified three sites of TSC2 phosphorylation and a novel site of TSC1 phosphorylation, and investigated the roles of these sites in regulating the activity of the TSC1-TSC2 complex. In addition, we identified three TSC1-TSC2 interacting proteins, including DOCK7 a putative rhebGEF.