Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tuberous sclerosis (TS) is an autosomal dominant disorder in which affected individuals manifest mental retardation, seizures, and a variety of benign and malignant tumors. The TSC2 tumor suppressor gene was recently identified by positional cloning and its protein product, tuberin, shown to represent one member of the rap GTPase activating protein (rapGAP) family. In order to determine the contribution of tuberin to the development of mental retardation and seizures in patients with TS, we examined the expression of tuberin in adult and developing nervous system tissues. Since tuberin is the second rapGAP found in the nervous system, the expression of tuberin was compared to the expression of rapGAP, rap1, and rap2. In this study, we demonstrate that tuberin is expressed at greatest levels in the spinal cord and cerebellum as opposed to rapGAP, which is not enriched in these tissues. Tuberin expression in the adult CNS is restricted to the olfactory bulb, several CNS neuronal populations, brainstem nuclei, cerebellar Purkinje cells, and motor neurons in the ventral spinal cord. In contrast, rapGAP is expressed in many different cell types in the adult CNS, but not in cerebellar Purkinje cells or motor neurons in the ventral spinal cord. However, there is significant expression of rapGAP in astrocytes. The restricted distribution of tuberin expression relative to rap1 and rapGAP suggests that tuberin may be the primary rap1 regulator in a subpopulation of CNS neurons.
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PMID:Expression of the tuberous sclerosis 2 gene product, tuberin, in adult and developing nervous system tissues. 917 18

Tuberous sclerosis complex (TSC) is a tumor suppressor gene syndrome characterized by seizures, mental retardation, autism, and tumors of the brain, kidney, heart, retina, and skin. TSC is caused by mutations in either TSC1 or TSC2, both of which are tumor suppressor genes. Hamartin, the protein product of TSC1, was found to interact with the ezrin-radixin-moesin family of cytoskeletal proteins and to activate the small GTPase Rho. To determine whether tuberin, the TSC2 product, can also activate Rho, we stably expressed full-length human tuberin in two cell types: MDCK cells and ELT3 cells. ELT3 cells lack endogenous tuberin expression. We found that expression of human tuberin in both MDCK and ELT3 cells was associated with an increase in the amount of Rho-GTP, but not in Rac1-GTP or cdc42-GTP. Tuberin expression increased cell adhesion in both cell types, and decreased chemotactic cell migration in ELT3 cells. In MDCK cells, there was a decrease in the amount of total Focal Adhesion Kinase (FAK) and an increase in the fraction of phosphorylated FAK. These findings demonstrate for the first time that tuberin activates Rho and regulates cell adhesion and migration. Pathways involving Rho activation may have relevance to the clinical manifestations of TSC, including pulmonary lymphangioleiomyomatosis.
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PMID:Tuberin, the tuberous sclerosis complex 2 tumor suppressor gene product, regulates Rho activation, cell adhesion and migration. 1246 66

Tuberous sclerosis complex is a tumor suppressor gene syndrome whose manifestations can include seizures, mental retardation, and benign tumors of the brain, skin, heart, and kidneys. Hamartin and tuberin, the products of the TSC1 and TSC2 genes, respectively, form a complex and inhibit signaling by the mammalian target of rapamycin. Here, we demonstrate that endogenous hamartin is threonine-phosphorylated during nocodazole-induced G2/M arrest and during the G2/M phase of a normal cell cycle. In vitro assays showed that cyclin-dependent kinase 1 phosphorylates hamartin at three sites, one of which (Thr417) is in the hamartin-tuberin interaction domain. Tuberin interacts with phosphohamartin, and tuberin expression attenuates the phosphorylation of exogenous hamartin. Hamartin with alanine mutations in the three cyclin-dependent kinase 1 phosphorylation sites increased the inhibition of p70S6 kinase by the hamartin-tuberin complex. These findings support a model in which phosphorylation of hamartin regulates the function of the hamartin-tuberin complex during the G2/M phase of the cell cycle.
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PMID:Cell cycle-regulated phosphorylation of hamartin, the product of the tuberous sclerosis complex 1 gene, by cyclin-dependent kinase 1/cyclin B. 1455 Dec 5

Tuberous Sclerosis Complex (TSC) is an autosomal dominant disorder associated with mutations in TSC1, which codes for hamartin, or TSC2, which codes for tuberin. The brain is one of the most severely affected organs, and CNS lesions include cortical tubers and subependymal giant cell astrocytomas, resulting in mental retardation and seizures. Tuberin and hamartin function together as a complex in mammals and Drosophila. We report here the association of Pam, a protein identified as an interactor of Myc, with the tuberin-hamartin complex in the brain. The C terminus of Pam containing the RING zinc finger motif binds to tuberin. Pam is expressed in embryonic and adult brain as well as in cultured neurons. Pam has two forms in the rat CNS, an approximately 450-kDa form expressed in early embryonic stages and an approximately 350-kDa form observed in the postnatal period. In cortical neurons, Pam co-localizes with tuberin and hamartin in neurites and growth cones. Although Pam function(s) are yet to be defined, the highly conserved Pam homologs, HIW (Drosophila) and RPM-1 (Caenorhabditis elegans), are neuron-specific proteins that regulate synaptic growth. Here we show that HIW can genetically interact with the Tsc1.Tsc2 complex in Drosophila and could negatively regulate Tsc1.Tsc2 activity. Based on genetic studies, HIW has been implicated in ubiquitination, possibly functioning as an E3 ubiquitin ligase through the RING zinc finger domain. Therefore, we hypothesize that Pam, through its interaction with tuberin, could regulate the ubiquitination and proteasomal degradation of the tuberin-hamartin complex particularly in the CNS.
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PMID:Pam and its ortholog highwire interact with and may negatively regulate the TSC1.TSC2 complex. 1455 97

Desiree-Magloire Bourneville first reported tuberous sclerosis complex as "tuberous sclerosis of the cerebral convolutions" in 1880. This disorder is characterized by multiple hamartomas in several organs, particularly the brain. Commonly recognized clinical features include hypomelanotic skin macules, facial angiofibromas, periungual fibromas, delayed development, and seizures. Abnormalities on brain imaging include subependymal nodules, cortical tubers, and radial white matter lines. The kidney, heart, and retina are among other commonly affected organs. Although the majority of cases (65%) are sporadic, genetic linkage studies of familial cases led to the discovery of two separate genes linked to tuberous sclerosis complex: TSC1, located at chromosome 9q34, encoding a protein called hamartin; and TSC2, located at chromosome 16p13.3, encoding a protein called tuberin. Tuberin has a region of homology to rap1GAP, a guanosine triphosphatase-activating protein. This observation is consistent with the idea of tuberin functioning in a cellular signaling pathway. Hamartin contains a single potential transmembrane domain; orthologues in yeast, drosophila, and rat have been cloned. Hamartin also binds to ezrin and other ezrin-radixin-moesin proteins, which link the cell membrane to the cytoskeleton. Tuberin and hamartin interact directly with each other, and the complex may function together to regulate specific cellular processes. This study reviews current ideas regarding the function of tuberin and hamartin, and the pathogenesis of tuberous sclerosis complex.
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PMID:Tuberous sclerosis complex: genetics to pathogenesis. 1468 35

Tuberous sclerosis complex (TSC) is an autosomal dominant tumor syndrome that affects approximately 1 in 6000 individuals. It is characterized by the development of tumors, named hamartomas, in the kidneys, heart, skin and brain. The latter often cause seizures, mental retardation, and a variety of developmental disorders, including autism. This disease is caused by mutations within the tumor suppressor gene TSC1 on chromosome 9q34 encoding hamartin or within TSC2 on chromosome 16p13.3 encoding tuberin. TSC patients carry a mutant TSC1 or TSC2 gene in each of their somatic cells, and loss of heterozygosity has been documented in a wide variety of TSC tumors. Recent data suggest that functional inactivation of TSC proteins might also be involved in the development of other diseases not associated with TSC, such as sporadic bladder cancer, breast cancer, ovarian carcinoma, gall bladder carcinoma, non-small-cell carcinoma of the lung, and Alzheimer's disease. Tuberin and hamartin form a heterodimer, suggesting they might affect the same processes. Tuberin is assumed to be the functional component of the complex and has been implicated in the regulation of different cellular functions. The TSC proteins regulate cell size control due to their involvement in the insulin signalling pathway. Furthermore, they are potent positive regulators of the cyclin-dependent kinase inhibitor p27, a major regulator of the mammalian cell cycle. Here we review the current knowledge on how mutations within the TSC genes could trigger deregulation of stability and localization of the tumor suppressor p27.
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PMID:The tuberous sclerosis genes and regulation of the cyclin-dependent kinase inhibitor p27. 1671 32

Tuberous sclerosis complex (TSC) is an inherited disorder resulting from mutations in one of two genes, TSC1 (Hamartin) and TSC2 (Tuberin). These two proteins form a cytosolic complex that inhibits the mTOR pathway that controls cell growth and proliferation. Pathologically, abnormalities of neuronal migration, cellular differentiation and excessive cellular proliferation all contribute to the formation of the different brain lesions of TSC. Seizure is the most common presenting symptom. Seizures can be present in the first year of life and up to one third of children develop infantile spasms. Seizures usually have a focal or multifocal origin, are often resistant to antiepileptic drugs and have a negative impact on the neurocognitive development. Vigabatrin has proved to be effective against infantile spasms due to TSC. New evidence suggests that it is possible to noninvasively identify using multimodality techniques, TSC children who are likely to become seizure-free following surgical treatment. Understanding the mechanisms of epileptogenesis and the possible role of the mTOR pathway in this process might increase the availability of novel and targeted therapies.
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PMID:Management of epilepsy in tuberous sclerosis complex. 1834 74

Tuberous sclerosis complex (TSC) is a genetic disease characterized by multiorgan benign tumors as well as neurological manifestations. Epilepsy and autism are two of the more prevalent neurological complications and are usually severe. TSC is caused by mutations in either the TSC1 (encodes hamartin) or the TSC2 (encodes tuberin) genes with TSC2 mutations being associated with worse outcomes. Tuberin contains a highly conserved GTPase-activating protein (GAP) domain that indirectly inhibits mammalian target of rapamycin complex 1 (mTORC1). mTORC1 dysregulation is currently thought to cause much of the pathogenesis in TSC but mTORC1-independent mechanisms may also contribute. We generated a novel conditional allele of Tsc2 by flanking exons 36 and 37 with loxP sites. Mice homozygous for this knock-in Tsc2 allele are viable and fertile with normal appearing growth and development. Exposure to Cre recombinase then creates an in-frame deletion involving critical residues of the GAP domain. Homozygous conditional mutant mice generated using Emx1(Cre) have increased cortical mTORC1 signaling, severe developmental brain anomalies, seizures, and die within 3 weeks. We found that the normal levels of the mutant Tsc2 mRNA, though GAP-deficient tuberin protein, appear unstable and rapidly degraded. This novel animal model will allow further study of tuberin function including the requirement of the GAP domain for protein stability.
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PMID:Conditional and domain-specific inactivation of the Tsc2 gene in neural progenitor cells. 2335 22