Bcl-2 or Bcl-XL gene therapy reduces apoptosis and increases plasticity protein GAP-43 in PC12 cells

LncRNA SNHG1 protects SH-SY5Y cells from hypoxic injury through miR-140-5p/Bcl-XL axis

Background: Hypoxic brain injury is one of the major causes of neurodevelopmental impairment and cardiovascular disability. LncRNA SNHG1 works as a critical factor in hypoxic induced injury, however, the potential mechanism is still not known well.Methods: The expression level of small nucleolar RNA host gene 1 (SNHG1) and miR-140-5p was detected by qRT-PCR. The western blot assay was performed to measure the level of Bcl-XL and apoptosis-related proteins. The target relationship between lncRNA SNHG1 and miR-140-5p, as well as miR-140-5p and Bcl-XL was detected by dual luciferase reporter gene assay. Cell apoptosis was assessed using Annexin V/PI staining by flow cytometry. Cell viability was analyzed by MTT assay.Results: Oxygen glucose deprivation (OGD) treatment inhibited SNHG1 and Bcl-XL expression and enhanced miR-140-5p expression. OGD treatment-induced cell viability inhibition, cell apoptosis promotion were partially abrogated when SH-SY5Y cells were transfected with pcDNA3.1-SNHG1 or miR-140-5p inhibitor. Moreover, luciferase reporter assay revealed that lncRNA SNHG1 bound directly to miR-140-5p, and miR-140-5p directly targeted Bcl-XL. The protective effect of SNHG1 overexpressing on cell apoptosis induced by OGD was attenuated after transfected with miR-140-5p mimic or sh-Bcl-XL in SH-SY5Y cells.Conclusion: LncRNA SNHG1-modulated miR-140-5p inhibition regulates Bcl-XL expression, thereby reducing cell apoptosis and recovering cell viability of SH-SY5Y cells. The results in this study provide novel insight into the mechanism of SNHG1 mediated signaling pathway during hypoxic brain injury.

Long-Term Changes of Diffusion Tensor Imaging and Behavioural Status after Acupuncture Treatment in Rats with Transient Focal Cerebral Ischaemia

Background

The effect of acupuncture treatment in cerebral ischaemia is controversial. A study was undertaken to assess its effects in rats with transient middle cerebral artery occlusion (tMCAO) and discuss its mechanisms.

Methods

21 Sprague–Dawley rats were divided into three groups. Group 1 underwent tMCAO and subsequently received acupuncture treatment, Group 2 underwent tMCAO without treatment and Group 3 only underwent sham operation. The evolution of diffusion tensor imaging (DTI) features in ischaemic lesions from acute to chronic periods was assessed and the correlations with behavioural tests and histopathological changes were examined.

Results

tMCAO rats displayed side-specific sensorimotor deficits after occlusion. Behavioural scores of rats in group 1 reduced gradually with acupuncture treatment. No significant difference in lesion size on T2-weighted imaging was found between the two tMCAO groups. Relative apparent diffusion coefficient (rADC) and relative fractional anisotropy (rFA) values in the centre and at the edge of the ischaemic lesions reduced at first and then increased to varying degrees. Only changes in the rFA value at the edge of the ischaemic lesions were significantly different between the two tMCAO groups. A more significant increase in growth-associated protein B-50 and synaptophysin protein expression was found in group 1 than in the other groups. No significant correlations were found between behavioural scores, DTI appearances and immunohistochemical results.

Conclusions

The acupuncture points applied were effective, and improving neuronal regeneration may have a role in the mechanism of acupuncture treatment of post-stroke paralysis of the limbs in rats. MRI, particularly the fractional anisotropy value of DTI, is an appropriate parameter to evaluate the recovery status.

Cerebral ischemia/repefusion injury: From bench space to bedside

While stroke research represents the primary interface between circulation and brain research, the hemostasis system also carries a pivotal role in the mechanism of vascular brain injury. The complex interrelated events triggered by the energy crisis have a specific spatial and temporal pattern arching from the initial damage to the final events of brain repair. The complexity of the pathophysiology make it difficult to model this disease, therefore it is challenging to find appropriate therapeutic targets. The ever-persistent antagonism between the positive results of drug candidates in the experimental stroke models and the failures of the clinical trials prompts changes in the research strategy, especially in the field of potential neuroprotective therapies. System biology approach could initiate new directions in the future for both preclinical and clinical research. Incentive methods aimed at anti-apoptosis mechanisms and the augmentation of post-ischemic brain repair could benefit the facts, that these processes can be targeted much longer following the cell-necrosis in the hyper-acute phase. Sequential monitoring of candidate genes and proteins responsible for stroke progression and post-stroke repair seems to be useful both in therapeutic target-identification, and in clinical testing. Understanding the mechanism behind the effect of selegiline and other drugs capable of activating the anti-apoptotic gene expression could help to find new approaches to enhance the regenerative potential in the remodeling of neuronal and microvascular networks.

Insulin promotes neuronal survival via the alternatively spliced protein kinase CδII isoform

Insulin signaling pathways in the brain regulate food uptake and memory and learning. Insulin and protein kinase C (PKC) pathways are integrated and function closely together. PKC activation in the brain is essential for learning and neuronal repair. Intranasal delivery of insulin to the central nervous system (CNS) has been shown to improve memory, reduce cerebral atrophy, and reverse neurodegeneration. However, the neuronal molecular mechanisms of these effects have not been studied in depth. PKCδ plays a central role in cell survival. Its splice variants, PKCδI and PKCδII, are switches that determine cell survival and fate. PKCδI promotes apoptosis, whereas PKCδII promotes survival. Here, we demonstrate that insulin promotes alternative splicing of PKCδII isoform in HT22 cells. The expression of PKCδI splice variant remains unchanged. Insulin increases PKCδII alternative splicing via the PI3K pathway. We further demonstrate that Akt kinase mediates phosphorylation of the splicing factor SC35 to promote PKCδII alternative splicing. Using overexpression and knockdown assays, we demonstrate that insulin increases expression of Bcl2 and bcl-xL via PKCδII. We demonstrate increased cell proliferation and increased BrdU incorporation in insulin-treated cells as well as in HT22 cells overexpressing PKCδII. Finally, we demonstrate in vivo that intranasal insulin promotes cognitive function in mice with concomitant increases in PKCδII expression in the hippocampus. This is the first report of insulin, generally considered a growth or metabolic hormone, regulating the alternative isoform expression of a key signaling kinase in neuronal cells such that it results in increased neuronal survival.

(-)Deprenyl-N-oxide, a (-)deprenyl metabolite, is cytoprotective after hypoxic injury in PC12 cells, or after transient brain ischemia in gerbils

BACKGROUND AND AIMS

(-)-Deprenyl (selegiline) possesses cyto-protective effect in a much lower concentration, than it is needed to inhibit MAO-B activity. In permanent MCA occlusion stroke model in rats, the infarct volume and the number of apoptotic neurons in the penumbra region were decreased by low concentration (-)deprenyl treatment. Augmented Bcl-2 protein expression was documented as the responsible factor of this effect. The stabilization of mitochondrial membrane and diminished ROS production are the further possible consequences of (-)deprenyl treatment. It is not clear however that (-)deprenyl, or its metabolites are the acting neuroprotective molecules in the hypoxic/ischemic conditions. We report here the possible cyto-protective effect of deprenyl-N-oxide (DNO), a recently synthesized (-)deprenyl metabolite.

METHODS

DNO in a very low dose (10(-5,-8,-12) M) was tested in PC12 cell culture after hypoxia and in gerbils after transient occlusion of bilateral common carotid artery. In PC12 culture the cell death was visualized by PI staining. The level of reactive oxygen species was measured by the Cerium method, and the mitochondrial membrane integrity was labeled by JC1 staining. Apoptotic neurons were counted on formaldehyde fixed gerbil brain slices after TUNEL and caspase-3 immune-staining - NIKON/BIORAD confocal microscopy was used for the quantitative analysis.

RESULTS

DNO treatment significantly decreased the frequency of cell death in PC12 cultures after hypoxia, increased the mitochondrial transmembrane potential (DeltaY(m)) and decreased the ROS production. In the CA2 regions of gerbil hippocampus, we found significantly less apoptotic neurons than in the untreated controls.

CONCLUSION

Transient hypoxia or ischemia induced cell damage could be diminished by DNO. This (-)deprenyl metabolite is an active cell protective molecule.