Jiahang Sun

Administration of simvastatin after kainic acid-induced status epilepticus restrains chronic temporal lobe epilepsy.

In this study, we examined the effect of chronic administration of simvastatin immediately after status epilepticus (SE) on rat brain with temporal lobe epilepsy (TLE). First, we evaluated cytokines expression at 3 days post KA-lesion in hippocampus and found that simvastatin-treatment suppressed lesion-induced expression of interleukin (IL)-1β and tumor necrosis factor-α (TNF-α). Further, we quantified reactive astrocytosis using glial fibrillary acidic protein (GFAP) staining and neuron loss using Nissl staining in hippocampus at 4–6 months after KA-lesion. We found that simvastatin suppressed reactive astrocytosis demonstrated by a significant decrease in GFAP-positive cells, and attenuated loss of pyramidal neurons in CA3 and interneurons in dentate hilar (DH). We next assessed aberrant mossy fiber sprouting (MFS) that is known to contribute to recurrence of spontaneous seizure in epileptic brain. In contrast to the robust MFS observed in saline-treated animals, the extent of MFS was restrained by simvastatin in epileptic rats. Attenuated MFS was related to decreased neuronal loss in CA3 and DH, which is possibly a mechanism underlying decreased hippocampal susceptibility in animal treated with simvastatin. Electronic encephalography (EEG) was recorded during 4 to 6 months after KA-lesion. The frequency of abnormal spikes in rats with simvastatin-treatment decreased significantly compared to the saline group. In summary, simvastatin treatment suppressed cytokines expression and reactive astrocytosis and decreased the frequency of discharges of epileptic brain, which might be due to the inhibition of MFS in DH. Our study suggests that simvastatin administration might be a possible intervention and promising strategy for preventing SE exacerbating to chronic epilepsy.

miR-656 Inhibits Glioma Tumorigenesis Through Repression of BMPR1A

Bone morphogenetic protein-2 (BMP-2), a member of the transforming growth factor-β family, plays critical roles in cell differentiation, modeling and regeneration processes in several tissues. BMP-2 is also closely associated with various malignant tumors. microRNAs negatively and posttranscriptionally regulate gene expression and function as oncogenes or tumor suppressors. Herein, we report that miR-656 expression was significantly downregulated in glioma cell lines and tissues. We identified and confirmed that BMP receptor, type 1A (BMPR1A) is a direct target of miR-656. The expression of BMPR1A was negatively correlated with that of miR-656 in human glioma tissues. We further demonstrated that miR-656 suppressed glioma cell proliferation, neurosphere formation, migration and invasion with or without exogenous BMP-2. Engineered knockdown of BMPR1A diminished the antiproliferation effect of miR-656 in vitro. Moreover, the canonical BMP/Smad and non-canonical BMP/mitogen-activated protein kinase (MAPK) pathways were inhibited by miR-656 overexpression. Several cancer-related signaling molecules, including cyclin B, cyclin D1, matrix metalloproteinase-9, p21 and p27, were also involved in miR-656 function in glioma cells. The tumor-suppressing function of miR-656 was validated using an in vivo intracranial xenograft mouse model. Notably, ectopic expression of miR-656 markedly reduced tumor size and prolonged the survival of mice treated with or without BMP-2. These results elucidate the function of miR-656 in glioma progression and suggest a promising application for glioma treatment.

Protection against cognitive impairment and modification of epileptogenesis with curcumin in a post-status epilepticus model of temporal lobe epilepsy

Epileptogenesis is a dynamic process initiated by insults to the brain that is characterized by progressive functional and structural alterations in certain cerebral regions, leading to the appearance of spontaneous recurrent seizures. Within the duration of the trauma to the brain and the appearance of spontaneous recurrent seizures, there is typically a latent period, which may offer a therapeutic window for preventing the emergence of epilepsy. Previous animal studies have shown that curcumin can attenuate acute seizure severity and brain oxidative stress, but the effect of curcumin on epileptogenesis has not been studied. We examined the effect of continued administration of curcumin during the latent period on epileptogenesis and the deleterious consequences of status epilepticus in adult rats in a post-status epilepticus model of temporal lobe epilepsy induced by kainic acid. We demonstrate that, while administration of curcumin treatment during the latent period does not prevent occurrence of spontaneous recurrent seizures after status epilepticus, it can attenuate the severity of spontaneous recurrent seizures and protect against cognitive impairment. Thus, treatment with curcumin during the latent period following status epilepticus is beneficial in modifying epileptogenesis.

The effects of simvastatin on hippocampal caspase-3 and Bcl-2 expression following kainate-induced seizures in rats

Status epilepticus (SE) causes neuronal loss and apoptosis by inducing several apoptosis-regulatory genes. Two such genes, cysteinyl aspartate-specific protease-3 (caspase-3), an apoptosis activator, and B-cell leukemia-2 (Bcl-2), an apoptosis suppressor, are tightly regulated for their expression and activation. Statins, inhibitors of HMG-CoA reductase, have been recently recognized as neuroprotective drugs. However, their underlying mechanisms are still unclear. In this study, we examined the neuroprotective effects of simvastatin in a rat model of SE induced by kainic acid (KA). Feeding of simvastatin for 3 days after kainate injection rescued SE-induced neuronal apoptosis, as determined by histological examination of brain sections at the level of the dorsal hippocampus. Semi-quantitative RT-PCR showed that SE treatment markedly increased caspase-3 mRNA expression and reduced Bcl-2 mRNA expression in the hippocampus. Similarly, western blot analysis and immunohistochemical analysis of the rat hippocampus demonstrated that under SE treatment, caspase-3 protein levels significantly increased and peaked at 72 h, whereas Bcl-2 protein levels decreased from 6-24 h following SE. Interestingly, simvastatin could reverse the aforementioned SE-induced changes, suggesting that the neuroprotective effects of simvastatin against neuronal apoptosis may be achieved by inhibiting caspase-3 expression and increasing Bcl-2 expression.

Centrosomal Protein of 55 Regulates Glucose Metabolism, Proliferation and Apoptosis of Glioma Cells via the Akt/mTOR Signaling Pathway.

Introduction: Glioma is one of the most common and most aggressive brain tumors in humans. The molecular and cellular mechanisms responsible for the onset and the progression of glioma are elusive and controversial. Centrosomal protein of 55 (CEP55) was initially described as a highly coiled-coil protein that plays critical roles in cell division, but was recently identified as being overexpressed in many human cancers. The function of CEP55 has not previously been characterized in glioma. We aim to discover the effect and mechanism of CEP55 in glioma development. Method: qRT-PCR and immunohistochemistry were used to analyze CEP55 expression. Glucose uptake, western blot, MTS, CCK-8, Caspase-3 activity and TUNEL staining assays were performed to investigate the role and mechanism of CEP55 on glioma cell process. Results: We found that the levels of CEP55 expression were upregulated in glioma. In addition, CEP55 appeared to regulate glucose metabolism of glioma cells. Furthermore, knockdown of CEP55 inhibited cell proliferation and induced cell apoptosis in glioma. Finally, we provided preliminary evidence that knockdown of CEP55 inhibited glioma development via suppressing the activity of Akt/mTOR signaling. Conclusions: Our results demonstrated that CEP55 regulates glucose metabolism, proliferation and apoptosis of glioma cells via the Akt/mTOR signaling pathway, and its promotive effect on glioma tumorigenesis can be a potential target for glioma therapy in the future.

Antagomirs Targeting MiroRNA-134 Attenuates Epilepsy in Rats through Regulation of Oxidative Stress, Mitochondrial Functions and Autophagy

The effects of the existing anti-epileptic drugs are unsatisfactory to almost one third of epileptic patients. MiR-134 antagomirs prevent pilocarpine-induced status epilepticus. In this study, a lithium chloride-pilocarpine-induced status epilepticus model was established and treated with intracerebroventricular injection of antagomirs targeting miR-134 (Ant-134). The Ant-134 treatment significantly improved the performance of rats in Morris water maze tests, inhibited mossy fiber sprouting in the dentate gyrus, and increased the survival neurons in the hippocampal CA1 region. Silencing of miR-134 remarkably decreased malonaldehyde and 4-hydroxynonenal levels and increased superoxide dismutase activity in the hippocampus. The Ant-134 treatment also significantly increased the production of ATP and the activities of mitochondrial respiratory enzyme complexes and significantly decreased the reactive oxygen species generation in the hippocampus compared with the status epilepticus rats. Finally, the Ant-134 treatment remarkably downregulated the hippocampal expressions of autophagy-associated proteins Atg5, beclin-1 and light chain 3B. In conclusion, Ant-134 attenuates epilepsy via inhibiting oxidative stress, improving mitochondrial functions and regulating autophagy in the hippocampus.

Antagomirs Targeting MicroRNA-134 Increase Limk1 Levels After Experimental Seizures in Vitro and in Vivo

Background: MiR-134 is enriched in dendrites of hippocampal neurons and plays crucial roles in the progress of epilepsy. The present study aims to investigate the effects of antagomirs targeting miroRNA-134 (Ant-134) on limk1 expression and the binding of miR-134 and limk1 in experimental seizure. Methods: Status epilepticus (SE) rat model was established by lithium chloride-pilocarpine injection and was treated with Ant-134 by intracerebroventricular injection. Low Mg2+-exposed primary neurons were used as an in vitro model of SE. The expression of miR-134 was determined using real-time PCR. Protein expressions of limk1 and cofilin were determined by Western blotting. Luciferase reporter assay was used to examine the binding between miR-134 and limk1 3’-untranslated region. Results: The expression of miR-134 was markedly enhanced in hippocampus of the SE rats and low Mg2+-exposed neurons. Ant-134 increased the expression of limk1 and reduced the expression of cofilin in the SE hippocampus and Low Mg2+-exposed neurons. In addition, luciferase reporter assay confirmed that miR-134 bound limk1 3’-UTR. MiR-134 overexpression inhibited limk1 mRNA and protein expressions in neurons. Conclusion: Blockage of miR-134 upregulates limk1 expression and downregulated cofilin expression in hippocampus of the SE rats. This mechanism may contribute to the neuroprotective effects of Ant-134.