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1.
Cell ; 184(3): 655-674.e27, 2021 02 04.
Artículo en Inglés | MEDLINE | ID: mdl-33497611

RESUMEN

Ras GTPase-activating protein-binding proteins 1 and 2 (G3BP1 and G3BP2, respectively) are widely recognized as core components of stress granules (SGs). We report that G3BPs reside at the cytoplasmic surface of lysosomes. They act in a non-redundant manner to anchor the tuberous sclerosis complex (TSC) protein complex to lysosomes and suppress activation of the metabolic master regulator mechanistic target of rapamycin complex 1 (mTORC1) by amino acids and insulin. Like the TSC complex, G3BP1 deficiency elicits phenotypes related to mTORC1 hyperactivity. In the context of tumors, low G3BP1 levels enhance mTORC1-driven breast cancer cell motility and correlate with adverse outcomes in patients. Furthermore, G3bp1 inhibition in zebrafish disturbs neuronal development and function, leading to white matter heterotopia and neuronal hyperactivity. Thus, G3BPs are not only core components of SGs but also a key element of lysosomal TSC-mTORC1 signaling.


Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , ADN Helicasas/metabolismo , Lisosomas/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Proteínas de Unión a Poli-ADP-Ribosa/metabolismo , ARN Helicasas/metabolismo , Proteínas con Motivos de Reconocimiento de ARN/metabolismo , Proteínas de Unión al ARN/metabolismo , Transducción de Señal , Esclerosis Tuberosa/metabolismo , Secuencia de Aminoácidos , Animales , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Línea Celular Tumoral , Movimiento Celular/efectos de los fármacos , Gránulos Citoplasmáticos/efectos de los fármacos , Gránulos Citoplasmáticos/metabolismo , ADN Helicasas/química , Evolución Molecular , Femenino , Humanos , Insulina/farmacología , Proteínas de Membrana de los Lisosomas/metabolismo , Lisosomas/efectos de los fármacos , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Fenotipo , Proteínas de Unión a Poli-ADP-Ribosa/química , ARN Helicasas/química , Proteínas con Motivos de Reconocimiento de ARN/química , Ratas Wistar , Transducción de Señal/efectos de los fármacos , Pez Cebra/metabolismo
2.
Mol Cell ; 81(13): 2705-2721.e8, 2021 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-33974911

RESUMEN

The TSC complex is a critical negative regulator of the small GTPase Rheb and mTORC1 in cellular stress signaling. The TSC2 subunit contains a catalytic GTPase activating protein domain and interacts with multiple regulators, while the precise function of TSC1 is unknown. Here we provide a structural characterization of TSC1 and define three domains: a C-terminal coiled-coil that interacts with TSC2, a central helical domain that mediates TSC1 oligomerization, and an N-terminal HEAT repeat domain that interacts with membrane phosphatidylinositol phosphates (PIPs). TSC1 architecture, oligomerization, and membrane binding are conserved in fungi and humans. We show that lysosomal recruitment of the TSC complex and subsequent inactivation of mTORC1 upon starvation depend on the marker lipid PI3,5P2, demonstrating a role for lysosomal PIPs in regulating TSC complex and mTORC1 activity via TSC1. Our study thus identifies a vital role of TSC1 in TSC complex function and mTORC1 signaling.


Asunto(s)
Chaetomium , Proteínas Fúngicas , Lisosomas , Diana Mecanicista del Complejo 1 de la Rapamicina , Fosfatos de Fosfatidilinositol , Serina C-Palmitoiltransferasa , Chaetomium/química , Chaetomium/metabolismo , Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Lisosomas/química , Lisosomas/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/química , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Fosfatos de Fosfatidilinositol/química , Fosfatos de Fosfatidilinositol/metabolismo , Serina C-Palmitoiltransferasa/química , Serina C-Palmitoiltransferasa/metabolismo
3.
Am J Hum Genet ; 110(2): 251-272, 2023 02 02.
Artículo en Inglés | MEDLINE | ID: mdl-36669495

RESUMEN

For neurodevelopmental disorders (NDDs), a molecular diagnosis is key for management, predicting outcome, and counseling. Often, routine DNA-based tests fail to establish a genetic diagnosis in NDDs. Transcriptome analysis (RNA sequencing [RNA-seq]) promises to improve the diagnostic yield but has not been applied to NDDs in routine diagnostics. Here, we explored the diagnostic potential of RNA-seq in 96 individuals including 67 undiagnosed subjects with NDDs. We performed RNA-seq on single individuals' cultured skin fibroblasts, with and without cycloheximide treatment, and used modified OUTRIDER Z scores to detect gene expression outliers and mis-splicing by exonic and intronic outliers. Analysis was performed by a user-friendly web application, and candidate pathogenic transcriptional events were confirmed by secondary assays. We identified intragenic deletions, monoallelic expression, and pseudoexonic insertions but also synonymous and non-synonymous variants with deleterious effects on transcription, increasing the diagnostic yield for NDDs by 13%. We found that cycloheximide treatment and exonic/intronic Z score analysis increased detection and resolution of aberrant splicing. Importantly, in one individual mis-splicing was found in a candidate gene nearly matching the individual's specific phenotype. However, pathogenic splicing occurred in another neuronal-expressed gene and provided a molecular diagnosis, stressing the need to customize RNA-seq. Lastly, our web browser application allowed custom analysis settings that facilitate diagnostic application and ranked pathogenic transcripts as top candidates. Our results demonstrate that RNA-seq is a complementary method in the genomic diagnosis of NDDs and, by providing accessible analysis with improved sensitivity, our transcriptome analysis approach facilitates wider implementation of RNA-seq in routine genome diagnostics.


Asunto(s)
Perfilación de la Expresión Génica , Trastornos del Neurodesarrollo , Humanos , RNA-Seq , Cicloheximida , Análisis de Secuencia de ARN/métodos , Trastornos del Neurodesarrollo/diagnóstico , Trastornos del Neurodesarrollo/genética
4.
PLoS Biol ; 19(5): e3001279, 2021 05.
Artículo en Inglés | MEDLINE | ID: mdl-34038402

RESUMEN

Hyperactivation of the mammalian target of rapamycin (mTOR) pathway can cause malformation of cortical development (MCD) with associated epilepsy and intellectual disability (ID) through a yet unknown mechanism. Here, we made use of the recently identified dominant-active mutation in Ras Homolog Enriched in Brain 1 (RHEB), RHEBp.P37L, to gain insight in the mechanism underlying the epilepsy caused by hyperactivation of the mTOR pathway. Focal expression of RHEBp.P37L in mouse somatosensory cortex (SScx) results in an MCD-like phenotype, with increased mTOR signaling, ectopic localization of neurons, and reliable generalized seizures. We show that in this model, the mTOR-dependent seizures are caused by enhanced axonal connectivity, causing hyperexcitability of distally connected neurons. Indeed, blocking axonal vesicle release from the RHEBp.P37L neurons alone completely stopped the seizures and normalized the hyperexcitability of the distally connected neurons. These results provide new evidence of the extent of anatomical and physiological abnormalities caused by mTOR hyperactivity, beyond local malformations, which can lead to generalized epilepsy.


Asunto(s)
Proteína Homóloga de Ras Enriquecida en el Cerebro/metabolismo , Convulsiones/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Animales , Axones/metabolismo , Encéfalo/metabolismo , Modelos Animales de Enfermedad , Epilepsia/metabolismo , Epilepsia/fisiopatología , Ratones , Ratones Endogámicos C57BL , Neuronas/metabolismo , Convulsiones/fisiopatología , Transducción de Señal , Corteza Somatosensorial/metabolismo
5.
PLoS Genet ; 17(7): e1009651, 2021 07.
Artículo en Inglés | MEDLINE | ID: mdl-34197453

RESUMEN

Smith-Kingsmore syndrome (SKS) is a rare neurodevelopmental disorder characterized by macrocephaly/megalencephaly, developmental delay, intellectual disability, hypotonia, and seizures. It is caused by dominant missense mutations in MTOR. The pathogenicity of novel variants in MTOR in patients with neurodevelopmental disorders can be difficult to determine and the mechanism by which variants cause disease remains poorly understood. We report 7 patients with SKS with 4 novel MTOR variants and describe their phenotypes. We perform in vitro functional analyses to confirm MTOR activation and interrogate disease mechanisms. We complete structural analyses to understand the 3D properties of pathogenic variants. We examine the accuracy of relative accessible surface area, a quantitative measure of amino acid side-chain accessibility, as a predictor of MTOR variant pathogenicity. We describe novel clinical features of patients with SKS. We confirm MTOR Complex 1 activation and identify MTOR Complex 2 activation as a new potential mechanism of disease in SKS. We find that pathogenic MTOR variants disproportionately cluster in hotspots in the core of the protein, where they disrupt alpha helix packing due to the insertion of bulky amino acid side chains. We find that relative accessible surface area is significantly lower for SKS-associated variants compared to benign variants. We expand the phenotype of SKS and demonstrate that additional pathways of activation may contribute to disease. Incorporating 3D properties of MTOR variants may help in pathogenicity classification. We hope these findings may contribute to improving the precision of care and therapeutic development for individuals with SKS.


Asunto(s)
Trastornos del Neurodesarrollo/genética , Serina-Treonina Quinasas TOR/genética , Adulto , Preescolar , Discapacidades del Desarrollo/genética , Femenino , Humanos , Discapacidad Intelectual/genética , Masculino , Megalencefalia/genética , Persona de Mediana Edad , Mutación , Mutación Missense , Trastornos del Neurodesarrollo/fisiopatología , Fenotipo , Serina-Treonina Quinasas TOR/metabolismo
6.
Hum Mutat ; 43(12): 2130-2140, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-36251260

RESUMEN

Neurofibromatosis type 1 (NF1) is caused by inactivating mutations in NF1. Due to the size, complexity, and high mutation rate at the NF1 locus, the identification of causative variants can be challenging. To obtain a molecular diagnosis in 15 individuals meeting diagnostic criteria for NF1, we performed transcriptome analysis (RNA-seq) on RNA obtained from cultured skin fibroblasts. In each case, routine molecular DNA diagnostics had failed to identify a disease-causing variant in NF1. A pathogenic variant or abnormal mRNA splicing was identified in 13 cases: 6 deep intronic variants and 2 transposon insertions causing noncanonical splicing, 3 postzygotic changes, 1 branch point mutation and, in 1 case, abnormal splicing for which the responsible DNA change remains to be identified. These findings helped resolve the molecular findings for an additional 17 individuals in multiple families with NF1, demonstrating the utility of skin-fibroblast-based transcriptome analysis for molecular diagnostics. RNA-seq improves mutation detection in NF1 and provides a powerful complementary approach to DNA-based methods. Importantly, our approach is applicable to other genetic disorders, particularly those caused by a wide variety of variants in a limited number of genes and specifically for individuals in whom routine molecular DNA diagnostics did not identify the causative variant.


Asunto(s)
Neurofibromatosis 1 , Humanos , Neurofibromatosis 1/diagnóstico , Neurofibromatosis 1/genética , Neurofibromatosis 1/patología , Mutación , Empalme del ARN/genética , ADN , Fibroblastos/patología , Neurofibromina 1/genética
7.
Mod Pathol ; 34(2): 264-279, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-33051600

RESUMEN

Subependymal giant-cell astrocytomas (SEGAs) are slow-growing brain tumors that are a hallmark feature seen in 5-10% of patients with Tuberous Sclerosis Complex (TSC). Though histologically benign, they can cause serious neurologic symptoms, leading to death if untreated. SEGAs consistently show biallelic loss of TSC1 or TSC2. Herein, we aimed to define other somatic events beyond TSC1/TSC2 loss and identify potential transcriptional drivers that contribute to SEGA formation. Paired tumor-normal whole-exome sequencing was performed on 21 resected SEGAs from 20 TSC patients. Pathogenic variants in TSC1/TSC2 were identified in 19/21 (90%) SEGAs. Copy neutral loss of heterozygosity (size range: 2.2-46 Mb) was seen in 76% (16/21) of SEGAs (44% chr9q and 56% chr16p). An average of 1.4 other somatic variants (range 0-7) per tumor were identified, unlikely of pathogenic significance. Whole transcriptome RNA-sequencing analyses revealed 190 common differentially expressed genes in SEGA (n = 16, 13 from a prior study) in pairwise comparison to each of: low grade diffuse gliomas (n = 530) and glioblastoma (n = 171) from The Cancer Genome Atlas (TCGA) consortium, ganglioglioma (n = 10), TSC cortical tubers (n = 15), and multiple normal tissues. Among these, homeobox transcription factors (TFs) HMX3, HMX2, VAX1, SIX3; and TFs IRF6 and EOMES were all expressed >12-fold higher in SEGAs (FDR/q-value < 0.05). Immunohistochemistry supported the specificity of IRF6, VAX1, SIX3 for SEGAs in comparison to other tumor entities and normal brain. We conclude that SEGAs have an extremely low somatic mutation rate, suggesting that TSC1/TSC2 loss is sufficient to drive tumor growth. The unique and highly expressed SEGA-specific TFs likely reflect the neuroepithelial cell of origin, and may also contribute to the transcriptional and epigenetic state that enables SEGA growth following two-hit loss of TSC1 or TSC2 and mTORC1 activation.


Asunto(s)
Astrocitoma/genética , Neoplasias Encefálicas/genética , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Proteína 1 del Complejo de la Esclerosis Tuberosa/genética , Proteína 2 del Complejo de la Esclerosis Tuberosa/genética , Adolescente , Astrocitoma/metabolismo , Neoplasias Encefálicas/metabolismo , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , Persona de Mediana Edad , Tasa de Mutación , Transcriptoma , Adulto Joven
8.
Hum Mutat ; 41(4): 759-773, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-31799751

RESUMEN

The TSC1 and TSC2 gene products interact to form the tuberous sclerosis complex (TSC), an important negative regulator of the mechanistic target of rapamycin complex 1 (TORC1). Inactivating mutations in TSC1 or TSC2 cause TSC, and the identification of a pathogenic TSC1 or TSC2 variant helps establish a diagnosis of TSC. However, it is not always clear whether TSC1 and TSC2 variants are inactivating. To determine whether TSC1 and TSC2 variants of uncertain clinical significance affect TSC complex function and cause TSC, in vitro assays of TORC1 activity can be employed. Here we combine genetic, functional, and structural approaches to try and classify a series of 15 TSC2 VUS. We investigated the effects of the variants on the formation of the TSC complex, on TORC1 activity and on TSC2 pre-mRNA splicing. In 13 cases (87%), the functional data supported the hypothesis that the identified TSC2 variant caused TSC. Our results illustrate the benefits and limitations of functional testing for TSC.


Asunto(s)
Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Mutación , Fenotipo , Proteína 2 del Complejo de la Esclerosis Tuberosa/química , Proteína 2 del Complejo de la Esclerosis Tuberosa/genética , Sustitución de Aminoácidos , Técnicas de Silenciamiento del Gen , Estudios de Asociación Genética/métodos , Genotipo , Humanos , Modelos Moleculares , Unión Proteica , Conformación Proteica , Multimerización de Proteína , Empalme del ARN , Relación Estructura-Actividad , Proteína 2 del Complejo de la Esclerosis Tuberosa/metabolismo
9.
Genet Med ; 22(5): 889-897, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32015538

RESUMEN

PURPOSE: Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder associated with cognitive deficits. The NF1 cognitive phenotype is generally considered to be highly variable, possibly due to the observed T2-weighted hyperintensities, loss of heterozygosity, NF1-specific genetic modifiers, or allelic imbalance. METHODS: We investigated cognitive variability and assessed the contribution of genetic factors by performing a retrospective cohort study and a monozygotic twin case series. We included data of 497 children with genetically confirmed NF1 and an IQ assessment, including 12 monozygotic twin and 17 sibling sets. RESULTS: Individuals carrying an NF1 chromosomal microdeletion showed significant lower full-scale IQ (FSIQ) scores than individuals carrying intragenic pathogenic NF1 variants. For the intragenic subgroup, the variability in cognitive ability and the correlation of IQ between monozygotic NF1 twin pairs or between NF1 siblings is similar to the general population. CONCLUSIONS: The variance and heritability of IQ in individuals with NF1 are similar to that of the general population, and hence mostly driven by genetic background differences. The only factor that significantly attenuates IQ in NF1 individuals is the NF1 chromosomal microdeletion genotype. Implications for clinical management are that individuals with intragenic NF1 variants that score <1.5-2 SD below the mean of the NF1 population should be screened for additional causes of cognitive disability.


Asunto(s)
Neurofibromatosis 1 , Niño , Cognición , Humanos , Pruebas de Inteligencia , Neurofibromatosis 1/genética , Estudios Retrospectivos , Gemelos Monocigóticos/genética
10.
J Natl Compr Canc Netw ; 16(4): 352-358, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29632054

RESUMEN

mTOR inhibitors are used to treat renal cell carcinoma (RCC). Treatment response is variable and appears to correlate with genetic alterations that activate mTOR signaling. Recently, everolimus was suggested to be more effective than sunitinib in chromophobe RCC (chRCC), a tumor with frequent mTOR pathway defects. This report presents the genomic and functional characterization of a metastatic chRCC that showed complete response at metastatic sites and 80% reduction in primary tumor size upon temsirolimus treatment. After surgery, the patient remained disease-free for 8 years after temsirolimus therapy. Whole-exome sequencing (WES) revealed 2 somatic variants in TSC2, a critical negative regulator of mTOR: a splicing defect (c.5069-1G>C) and a novel missense variant [c.3200_3201delinsAA; p.(V1067E)]. In vitro functional assessment demonstrated that the V1067E substitution disrupted TSC2 function. Immunohistochemistry in the tumor tissues revealed increased phosphorylated S6 ribosomal protein, indicating mTOR pathway activation. In conclusion, WES revealed TSC2 inactivation as the likely mechanism for this extraordinary response to temsirolimus. These findings support high efficacy of mTOR inhibitors in a subset of patients with chRCC and propose sequencing of mTOR pathway genes to help guide therapy.


Asunto(s)
Carcinoma de Células Renales/tratamiento farmacológico , Carcinoma de Células Renales/genética , Neoplasias Renales/tratamiento farmacológico , Neoplasias Renales/genética , Mutación , Sirolimus/análogos & derivados , Proteína 2 del Complejo de la Esclerosis Tuberosa/genética , Adulto , Antineoplásicos/administración & dosificación , Antineoplásicos/efectos adversos , Antineoplásicos/uso terapéutico , Biopsia , Análisis Mutacional de ADN , Femenino , Humanos , Inmunohistoquímica , Terapia Molecular Dirigida , Inhibidores de Proteínas Quinasas/administración & dosificación , Inhibidores de Proteínas Quinasas/efectos adversos , Inhibidores de Proteínas Quinasas/uso terapéutico , Sirolimus/administración & dosificación , Sirolimus/efectos adversos , Sirolimus/uso terapéutico , Tomografía Computarizada por Rayos X , Resultado del Tratamiento
11.
J Biol Chem ; 291(16): 8591-601, 2016 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-26893383

RESUMEN

Mutations in TSC1 or TSC2 cause tuberous sclerosis complex (TSC), an autosomal dominant disorder characterized by the occurrence of benign tumors in various vital organs and tissues. TSC1 and TSC2, the TSC1 and TSC2 gene products, form the TSC protein complex that senses specific cellular growth conditions to control mTORC1 signaling. TBC1D7 is the third subunit of the TSC complex, and helps to stabilize the TSC1-TSC2 complex through its direct interaction with TSC1. Homozygous inactivation of TBC1D7 causes intellectual disability and megaencephaly. Here we report the crystal structure of a TSC1-TBC1D7 complex and biochemical characterization of the TSC1-TBC1D7 interaction. TBC1D7 interacts with the C-terminal region of the predicted coiled-coil domain of TSC1. The TSC1-TBC1D7 interface is largely hydrophobic, involving the α4 helix of TBC1D7. Each TBC1D7 molecule interacts simultaneously with two parallel TSC1 helices from two TSC1 molecules, suggesting that TBC1D7 may stabilize the TSC complex by tethering the C-terminal ends of two TSC1 coiled-coils.


Asunto(s)
Proteínas Portadoras/química , Proteínas Supresoras de Tumor/química , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Cristalografía por Rayos X , Humanos , Péptidos y Proteínas de Señalización Intracelular , Estructura Cuaternaria de Proteína , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Proteína 1 del Complejo de la Esclerosis Tuberosa , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismo
12.
Biochim Biophys Acta ; 1863(11): 2658-2667, 2016 11.
Artículo en Inglés | MEDLINE | ID: mdl-27542907

RESUMEN

There is a growing evidence of the role of protein acetylation in different processes controlling metabolism. Sirtuins (histone deacetylases nicotinamide adenine dinucleotide-dependent) activate autophagy playing a protective role in cell homeostasis. This study analyzes tuberous sclerosis complex (TSC2) lysine acetylation, in the regulation of mTORC1 signaling activation, autophagy and cell proliferation. Nicotinamide 5mM (a concentration commonly used to inhibit SIRT1), increased TSC2 acetylation in its N-terminal domain, and concomitantly with an augment in its ubiquitination protein status, leading to mTORC1 activation and cell proliferation. In contrast, resveratrol (RESV), an activator of sirtuins deacetylation activity, avoided TSC2 acetylation, inhibiting mTORC1 signaling and promoting autophagy. Moreover, TSC2 in its deacetylated state was prevented from ubiquitination. Using MEF Sirt1 +/+ and Sirt1 -/- cells or a SIRT1 inhibitor (EX527) in MIN6 cells, TSC2 was hyperacetylated and neither NAM nor RESV were capable to modulate mTORC1 signaling. Then, silencing Tsc2 in MIN6 or in MEF Tsc2-/- cells, the effects of SIRT1 modulation by NAM or RESV on mTORC1 signaling were abolished. We also observed that two TSC2 lysine mutants in its N-terminal domain, derived from TSC patients, differentially modulate mTORC1 signaling. TSC2 K599M variant presented a lower mTORC1 activity. However, with K106Q mutant, there was an activation of mTORC1 signaling at the basal state as well as in response to NAM. This study provides, for the first time, a relationship between TSC2 lysine acetylation status and its stability, representing a novel mechanism for regulating mTORC1 pathway.


Asunto(s)
Autofagia , Complejos Multiproteicos/metabolismo , Transducción de Señal , Serina-Treonina Quinasas TOR/metabolismo , Proteínas Supresoras de Tumor/metabolismo , Acetilación , Animales , Autofagia/efectos de los fármacos , Carbazoles/farmacología , Línea Celular Tumoral , Proliferación Celular , Relación Dosis-Respuesta a Droga , Células HEK293 , Inhibidores de Histona Desacetilasas/farmacología , Humanos , Lisina , Diana Mecanicista del Complejo 1 de la Rapamicina , Ratones , Complejos Multiproteicos/genética , Niacinamida/farmacología , Dominios Proteicos , Procesamiento Proteico-Postraduccional , Estabilidad Proteica , Interferencia de ARN , Resveratrol , Transducción de Señal/efectos de los fármacos , Sirtuina 1/antagonistas & inhibidores , Sirtuina 1/metabolismo , Estilbenos/farmacología , Serina-Treonina Quinasas TOR/genética , Factores de Tiempo , Transfección , Proteína 2 del Complejo de la Esclerosis Tuberosa , Proteínas Supresoras de Tumor/genética
13.
Am J Med Genet A ; 173(3): 771-775, 2017 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-28211972

RESUMEN

Tuberous sclerosis complex (TSC) is an autosomal dominantly inherited disorder with variable expressivity associated with hamartomatous tumors, abnormalities of the skin, and neurologic problems including seizures, intellectual disability, and autism. TSC is caused by pathogenic variants in either TSC1 or TSC2. In general, TSC2 pathogenic variants are associated with a more severe phenotype than TSC1 pathogenic variants. Here, we report a pathogenic TSC2 variant, c.1864C>T, p.(Arg622Trp), associated with a mild phenotype, with most carriers meeting fewer than two major clinical diagnostic criteria for TSC. This finding has significant implications for counseling patients regarding prognosis. More patient data are required before changing the surveillance recommendations for patients with the reported variant. However, consideration should be given to tailoring surveillance recommendations for all pathogenic TSC1 and TSC2 variants with documented milder clinical sequelae. © 2017 Wiley Periodicals, Inc.


Asunto(s)
Alelos , Estudios de Asociación Genética , Mutación , Fenotipo , Esclerosis Tuberosa/diagnóstico , Esclerosis Tuberosa/genética , Proteínas Supresoras de Tumor/genética , Sustitución de Aminoácidos , Encéfalo/patología , Niño , Preescolar , Femenino , Genotipo , Humanos , Recién Nacido , Imagen por Resonancia Magnética , Masculino , Linaje , Rabdomioma/diagnóstico , Rabdomioma/genética , Rabdomioma/cirugía , Índice de Severidad de la Enfermedad , Proteína 2 del Complejo de la Esclerosis Tuberosa
14.
Croat Med J ; 58(6): 416-423, 2017 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-29308833

RESUMEN

We presented an extremely severe case of tuberous sclerosis complex (TSC) in a female patient with recurring, life-threatening bleeding complications related to renal angiomyolipomas. Massive intratumoral hemorrhage required surgical removal of both angiomyolipomatous kidneys and kidney transplantation. During the follow-up period, the patient developed severe metrorrhagia that eventually led to hysterectomy and salpingo-oophorectomy. Bleeding from the operative sites caused the loss of the first kidney transplant received from the mother, and immediate hemorrhagic shock led to the loss of the second, cadaveric kidney allograft. The third kidney transplant had a successful outcome. Pathological analysis of all tissue specimens showed TSC-associated lesions and deformed blood vessels in the surgically removed organs. Molecular genetic analysis of TSC1 and TSC2 in the DNA of peripheral leukocytes identified a novel TSC2 c.3599G>C (p.R1200P) variant. Functional assessment confirmed the likely pathogenicity of the TSC2 c.3599G>C (p.R1200P) variant. To the best of our knowledge, this is the first report of the c.3599G>C (p.R1200P) variant in exon 29 of the TSC2 gene related to a severe clinical course and multiple kidney transplants in a patient with TSC.


Asunto(s)
Angiomiolipoma/cirugía , Neoplasias Renales/cirugía , Trasplante de Riñón/efectos adversos , Mutación Missense , Hemorragia Posoperatoria/etiología , Esclerosis Tuberosa/genética , Proteínas Supresoras de Tumor/genética , Adulto , Angiomiolipoma/genética , Exones , Femenino , Humanos , Riñón/patología , Neoplasias Renales/genética , Recurrencia Local de Neoplasia , Proteína 2 del Complejo de la Esclerosis Tuberosa
15.
Hum Mutat ; 37(4): 364-70, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26703369

RESUMEN

Inactivating mutations in TSC1 and TSC2 cause tuberous sclerosis complex (TSC). The 2012 international consensus meeting on TSC diagnosis and management agreed that the identification of a pathogenic TSC1 or TSC2 variant establishes a diagnosis of TSC, even in the absence of clinical signs. However, exons 25 and 31 of TSC2 are subject to alternative splicing. No variants causing clinically diagnosed TSC have been reported in these exons, raising the possibility that such variants would not cause TSC. We present truncating and in-frame variants in exons 25 and 31 in three individuals unlikely to fulfil TSC diagnostic criteria and examine the importance of these exons in TSC using different approaches. Amino acid conservation analysis suggests significantly less conservation in these exons compared with the majority of TSC2 exons, and TSC2 expression data demonstrates that the majority of TSC2 transcripts lack exons 25 and/or 31 in many human adult tissues. In vitro assay of both exons shows that neither exon is essential for TSC complex function. Our evidence suggests that variants in TSC2 exons 25 or 31 are very unlikely to cause classical TSC, although a role for these exons in tissue/stage specific development cannot be excluded.


Asunto(s)
Exones , Estudios de Asociación Genética , Mutación , Esclerosis Tuberosa/diagnóstico , Esclerosis Tuberosa/genética , Proteínas Supresoras de Tumor/genética , Adulto , Alelos , Empalme Alternativo , Niño , Preescolar , Biología Computacional/métodos , Bases de Datos Genéticas , Expresión Génica , Variación Genética , Humanos , Fenotipo , Proteína 2 del Complejo de la Esclerosis Tuberosa
16.
Hum Mutat ; 36(2): 200-9, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25366275

RESUMEN

The mechanistic target of rapamycin complex 1 (TORC1) senses nutrient availability to regulate eukaryotic anabolic metabolism. In response to limiting concentrations of amino acids, TORC1 kinase activity is inhibited through the GATOR-1 complex. Mutations in DEPDC5, that encodes one of the components of the GATOR-1 complex, have recently been associated with different forms of focal epilepsy. Here, we investigate the effects of 10 DEPDC5 variants identified in individuals with focal epilepsy and two DEPDC5 variants identified in serous ovarian tumors, on TORC1 signaling and GATOR-1 complex formation. According to our functional assessment, three variants clearly disrupted the DEPDC5-dependent inhibition of TORC1. We did not obtain functional evidence to support pathogenicity in the remaining cases. The observed functional differences between the DEPDC5 variants might underlie some of the clinical differences observed in the individuals carrying the different variants.


Asunto(s)
Proteínas Represoras/genética , Epilepsias Parciales/genética , Proteínas Activadoras de GTPasa/metabolismo , Estudios de Asociación Genética , Células HEK293 , Proteínas de Homeodominio/metabolismo , Humanos , Inmunoprecipitación , Diana Mecanicista del Complejo 1 de la Rapamicina , Complejos Multiproteicos/metabolismo , Mapeo de Interacción de Proteínas , Transducción de Señal , Serina-Treonina Quinasas TOR/metabolismo , Proteínas Supresoras de Tumor/metabolismo
17.
Mol Genet Metab ; 114(3): 467-73, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-25523067

RESUMEN

Activating germ-line and somatic mutations in AKT3 (OMIM 611223) are associated with megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome (MPPH; OMIM # 615937) and megalencephaly-capillary malformation (MCAP; OMIM # 602501). Here we report an individual with megalencephaly, polymicrogyria, refractory epilepsy, hypoglycemia and a germline AKT3 mutation. At birth, head circumference was 43 cm (5 standard deviations above the mean). No organomegaly was present, but there was generalized hypotonia, joint and skin laxity, developmental delay and failure to thrive. At 6 months of age the patient developed infantile spasms that were resistant to antiepileptic polytherapy. Recurrent hypoglycemia was noted during treatment with adrenocorticotropic hormone but stabilized upon introduction of continuous, enriched feeding. The infantile spasms responded to the introduction of a ketogenic diet, but the hypoglycemia recurred until the diet was adjusted for increased resting energy expenditure. A novel, de novo AKT3 missense variant (exon 5; c.548T>A, p.(V183D)) was identified and shown to activate AKT3 by in vitro functional testing. We hypothesize that the sustained hypoglycemia in this patient is caused by increased glucose utilization due to activation of AKT3 signaling. This might explain the efficacy of the ketogenic diet in this individual.


Asunto(s)
Epilepsia/genética , Mutación de Línea Germinal , Hipoglucemia/genética , Megalencefalia/genética , Polimicrogiria/genética , Proteínas Proto-Oncogénicas c-akt/genética , Anomalías Múltiples/etiología , Anomalías Múltiples/genética , Hormona Adrenocorticotrópica/uso terapéutico , Capilares/anomalías , Dieta Cetogénica , Epilepsia/etiología , Humanos , Hipoglucemia/etiología , Hipoglucemia/metabolismo , Lactante , Megalencefalia/etiología , Hipotonía Muscular/genética , Mutación , Polimicrogiria/etiología , Proteínas Proto-Oncogénicas c-akt/metabolismo , Radiografía , Cráneo/diagnóstico por imagen , Espasmos Infantiles/terapia , Malformaciones Vasculares/etiología , Malformaciones Vasculares/genética
18.
BMC Med Genet ; 16: 10, 2015 Feb 25.
Artículo en Inglés | MEDLINE | ID: mdl-25927202

RESUMEN

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. METHODS: Here we apply a targeted Next Generation Sequencing (NGS) approach to screen the complete TSC1 and TSC2 genomic loci in 7 individuals fulfilling the clinical diagnostic criteria for definite TSC in whom no TSC1 or TSC2 mutations were identified using conventional screening methods. RESULTS: We identified and confirmed pathogenic mutations in 3 individuals. In the remaining individuals we identified variants of uncertain clinical significance. The identified variants included mosaic changes, changes located deep in intronic sequences and changes affecting promoter regions that would not have been identified using exon-only based analyses. CONCLUSIONS: Targeted NGS of the TSC1 and TSC2 loci is a suitable method to increase the yield of mutations identified in the TSC patient population.


Asunto(s)
Análisis Mutacional de ADN , Secuenciación de Nucleótidos de Alto Rendimiento , Mutación , Proteínas Supresoras de Tumor/genética , Adolescente , Niño , Sitios Genéticos/genética , Genómica , Humanos , Persona de Mediana Edad , Esclerosis Tuberosa/genética , Proteína 1 del Complejo de la Esclerosis Tuberosa , Proteína 2 del Complejo de la Esclerosis Tuberosa
19.
J Pathol ; 233(3): 247-57, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24604753

RESUMEN

Most patients with tuberous sclerosis complex (TSC) develop cortical tubers that cause severe neurological disabilities. It has been suggested that defects in neuronal differentiation and/or migration underlie the appearance of tubers. However, the precise molecular alterations remain largely unknown. Here, by combining cytological and immunohistochemical analyses of tubers from nine TSC patients (four of them diagnosed with TSC2 germline mutations), we show that alteration of microtubule biology through ROCK2 signalling contributes to TSC neuropathology. All tubers showed a larger number of binucleated neurons than expected relative to control cortex. An excess of normal and altered cytokinetic figures was also commonly observed. Analysis of centrosomal markers suggested increased microtubule nucleation capacity, which was supported by the analysis of an expression dataset from cortical tubers and control cortex, and subsequently linked to under-expression of Rho-associated coiled-coil containing kinase 2 (ROCK2). Thus, augmented microtubule nucleation capacity was observed in mouse embryonic fibroblasts and human fibroblasts deficient in the Tsc2/TSC2 gene product, tuberin. Consistent with ROCK2 under-expression, microtubule acetylation was found to be increased with tuberin deficiency; this alteration was abrogated by rapamycin treatment and mimicked by HDAC6 inhibition. Together, the results of this study support the hypothesis that loss of TSC2 expression can alter microtubule organization and dynamics, which, in turn, deregulate cell division and potentially impair neuronal differentiation.


Asunto(s)
Corteza Cerebral/enzimología , Microtúbulos/enzimología , Neuronas/enzimología , Transducción de Señal , Esclerosis Tuberosa/enzimología , Quinasas Asociadas a rho/metabolismo , Animales , Estudios de Casos y Controles , Células Cultivadas , Corteza Cerebral/efectos de los fármacos , Corteza Cerebral/patología , Citocinesis , Fibroblastos/enzimología , Fibroblastos/patología , Predisposición Genética a la Enfermedad , Mutación de Línea Germinal , Histona Desacetilasa 6 , Inhibidores de Histona Desacetilasas/farmacología , Histona Desacetilasas/metabolismo , Humanos , Diana Mecanicista del Complejo 1 de la Rapamicina , Ratones , Microtúbulos/efectos de los fármacos , Microtúbulos/patología , Complejos Multiproteicos/antagonistas & inhibidores , Complejos Multiproteicos/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Neurogénesis , Neuronas/efectos de los fármacos , Neuronas/patología , Fenotipo , Inhibidores de Proteínas Quinasas/farmacología , Interferencia de ARN , Transducción de Señal/efectos de los fármacos , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Serina-Treonina Quinasas TOR/metabolismo , Transfección , Esclerosis Tuberosa/genética , Esclerosis Tuberosa/patología , Proteína 2 del Complejo de la Esclerosis Tuberosa , Tubulina (Proteína)/metabolismo , Proteínas Supresoras de Tumor/deficiencia , Proteínas Supresoras de Tumor/genética , Quinasas Asociadas a rho/genética
20.
Mod Pathol ; 27(10): 1321-30, 2014 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-24633195

RESUMEN

Uveal melanoma is a lethal cancer with a strong propensity to metastasize. Limited therapeutic options are available once the disease has disseminated. A strong predictor for metastasis is the loss of chromosome 3. Inactivating mutations in BAP1 encoding the BRCA1-associated protein 1 and located on chromosome 3p21.1, have been described in uveal melanoma and other types of cancer. In this study, we determined the prevalence of somatic BAP1 mutations and examined whether these mutations correlate with the functional expression of BAP1 in uveal melanoma tissue and with other clinical, histopathological and chromosomal parameters. We screened a cohort of 74 uveal melanomas for BAP1 mutations, using different deep sequencing methods. The frequency of BAP1 mutations in our study group was 47%. The expression of BAP1 protein was studied using immunohistochemistry. BAP1 staining was absent in 43% of the cases. BAP1 mutation status was strongly associated with BAP1 protein expression (P<0.001), loss of chromosome 3 (P<0.001), and other aggressive prognostic factors. Patients with a BAP1 mutation and absent BAP1 expression had an almost eightfold higher chance of developing metastases compared with those without these changes (P=0.002). We found a strong correlation between the immunohistochemical and sequencing data and therefore propose that, immunohistochemical screening for BAP1 should become routine in the histopathological work-up of uveal melanoma. Furthermore, our analysis indicates that loss of BAP1 may be particularly involved in the progression of uveal melanoma to an aggressive, metastatic phenotype.


Asunto(s)
Biomarcadores de Tumor/genética , Inmunohistoquímica , Melanoma/genética , Mutación , Proteínas Supresoras de Tumor/genética , Ubiquitina Tiolesterasa/genética , Neoplasias de la Úvea/genética , Adulto , Anciano , Anciano de 80 o más Años , Biomarcadores de Tumor/análisis , Análisis Mutacional de ADN , Femenino , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Hibridación Fluorescente in Situ , Estimación de Kaplan-Meier , Masculino , Melanoma/mortalidad , Melanoma/patología , Persona de Mediana Edad , Modelos de Riesgos Proporcionales , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Neoplasias de la Úvea/mortalidad , Neoplasias de la Úvea/patología
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