Authors: Blazejczyk M., Macias M., Korostynski M., Firkowska M., Piechota M., Skalecka A., Tempes A., Koscielny A., Urbanska M., Przewlocki R., Jaworski J.

Mol Neurobiol 2016 March 19; doi: 10.1007/s12035-016-9821-6

Abstract

Epileptogenesis is a process triggered by initial environmental or genetic factors that result in epilepsy and may continue during disease progression. Important parts of this process include changes in transcriptome and the pathological rewiring of neuronal circuits that involves changes in neuronal morphology. Mammalian/mechanistic target of rapamycin (mTOR) is upregulated by proconvulsive drugs, e.g., kainic acid, and is needed for progression of epileptogenesis, but molecular aspects of its contribution are not fully understood. Since mTOR can modulate transcription, we tested if rapamycin, an mTOR complex 1 inhibitor, affects kainic acid-evoked transcriptome changes. Using microarray technology, we showed that rapamycin inhibits the kainic acid-induced expression of multiple functionally heterogeneous genes. We further focused on engulfment and cell motility 1 (Elmo1), which is a modulator of actin dynamics and therefore could contribute to pathological rewiring of neuronal circuits during epileptogenesis. We showed that prolonged overexpression of Elmo1 in cultured hippocampal neurons increased axonal growth, decreased dendritic spine density, and affected their shape. In conclusion, data presented herein show that increased mTORC1 activity in response to kainic acid has no global effect on gene expression. Instead, our findings suggest that mTORC1 inhibition may affect development of epilepsy, by modulating expression of specific subset of genes, including Elmo1, and point to a potential role for Elmo1 in morphological changes that accompany epileptogenesis.


 

authors: Domanska-Pakiela D., Kaczorowska M., Jurkiewicz E., Kotulska K., Dunin-Wasowicz D., Jozwiak S.

Eur J Paediatr Neurol. 2014 Jul;18(4):458-68. doi: 10.1016/j.ejpn.2013.12.006.

Abstract

Tuberous sclerosis complex (TSC) is a multisystem, autosomal dominant disorder characterized by multiple hamartomas development. Epilepsy is the most common symptom appearing in 80-90% of the patients mainly in the first year of life. A prompt and early seizure control is crucial and can prevent development of an epileptic encephalopathy and secondary mental retardation. Therefore the very early identification of seizures seems to be of a great importance. We present the cases of 5patients diagnosed with TSC prenatally or perinatally and regularly monitored (at 4-6 weeks intervals) with EEG before theepilepsyonset. The patientsage at baseline varied from 9 days to 9 weeks. In all of the patients epileptiform discharges preceded the epilepsyonset. The time interval between abnormality detection on EEG and the epilepsyonset varied from 1 to 8 days. The patient's age at the epilepsyonset ranged from the 17th day to the 5th month of life. In one patient the EEG was abnormal from the beginning and in this patient the epileptic seizures started from the neonatal period. In the rest of thepatients (4/5) the EEG remained normal throughout the first months of life. In all of the children epilepsy started with focal motor seizures. Our study is the first prospective one showing the results of the EEG monitoring in TSC patients and the natural evolution of the EEG patterns in patients with the seizures types other than infantile spasms.

authors: Hu Z., Wang Y., Huang F., Chen R., Li C., Wang F., Goto J., Kwiatkowski DJ., Wdzieczak-Bakala J., Tu P., Liu J., Zha X., Zhang H.

J Biol Chem; 2015 Oct 16;290(42): 25756-65. doi: 10.1074/jbc.M115.665208.

Abstract

Frequent alteration of upstream proto-oncogenes and tumor suppressor genes activates mechanistictarget of rapamycin(mTOR) and causes cancer. However, the downstream effectors of mTOR remain largely elusive. Here we report that brain-expressedX-linked2 (BEX2) is a novel downstream effector of mTOR. Elevated BEX2 in Tsc2(-/-) mouse embryonic fibroblasts, Pten(-/-) mouse embryonic fibroblasts, Tsc2-deficient rat uterine leiomyoma cells, and brains of neuronal specific Tsc1 knock-out mice were abolished by mTOR inhibitor rapamycin. Furthermore, BEX2 was also increased in the liver of a hepatic specific Pten knock-out mouse and the kidneys of Tsc2 heterozygous deletion mice, and a patient with tuberous sclerosis complex (TSC). mTOR up-regulation of BEX2 was mediated in parallel by both STAT3 and NF-κB. BEX2 was involved in mTOR up-regulation of VEGF production and angiogenesis. Depletion of BEX2 blunted the tumorigenesis of cells with activated mTOR. Therefore, enhanced STAT3/NF-κB-BEX2-VEGF signaling pathway contributes to hyperactivemTOR-induced tumorigenesis. BEX2 may be targeted for the treatment of the cancers with aberrantly activated mTOR signaling pathway.

authors: Prabhakar S., Zhang X., Goto J., Han S., Lai C., Bronson R., Sena-Esteves M., Ramesh V., Stemmer-Rachamimov A., Kwiatkowski DJ., Breakefield XO.

Neurobiol Dis. 2015 Oct;82:22-31. doi: 10.1016/j.nbd.2015.04.018.

Abstract

We examined the potential benefit of genetherapy in a mousemodel of tuberoussclerosis complex (TSC) in which there is embryonic loss of Tsc1 (hamartin) in brain neurons. An adeno-associated virus (AAV) vector (serotype rh8) expressing a tagged form of hamartin was injected into the cerebral ventricles of newborn pups with the genotype Tsc1(cc) (homozygous for a conditional floxed Tsc1 allele) SynI-cre(+), in which Tsc1 is lost selectively in neurons starting at embryonic day 12. Vector-treated Tsc1(cc)SynIcre(+) mice showed a marked improvement in survival from a mean of 22 days in non-injected mice to 52 days in AAV hamartin vector-injected mice, with improved weight gain and motor behavior in the latter. Pathologic studies showed normalization of neuron size and a decrease in markers of mTOR activation in treated as compared to untreated mutant littermates. Hence, we show that gene replacement in the brain is an effective therapeutic approach in thismousemodel of TSC1. Our strategy for genetherapy has the advantages that therapy can be achieved from a single application, as compared to repeated treatment with drugs, and that AAV vectors have been found to have minimal to no toxicity in clinical trials for other neurologic conditions. Although there are many additional issues to be addressed, our studies support genetherapy as a useful approach in TSC patients.

authors: D'Gama AM., Geng Y., Couto JA., Martin B., Boyle EA., LaCoursiere CM., Hossain A., Hatem NE., Barry BJ., Kwiatkowski DJ., Vinters HV., Barkovich AJ., Shendure J., Mathern GW., Walsh GA., Poduri A.

Ann Neurol. 2015 Apr;77(4):720-5. doi: 10.1002/ana.24357.

Abstract

Focalmalformations of cortical development, including focalcortical dysplasia (FCD) and hemimegalencephaly (HME), are important causes of intractable childhood epilepsy. Using targeted and exome sequencing on DNA from resected brain samples and nonbrain samples from 53 patients with FCD or HME, we identified pathogenic germline and mosaic mutations in multiple PI3K/AKT pathway genes in 9 patients, and a likely pathogenic variant in 1 additional patient. Our data confirm the association of DEPDC5 with sporadic FCD but also implicate this gene for the first time in HME. Our findings suggest that modulation of the mammalian target of rapamycinpathway may hold promise for malformation-associated epilepsy.