Neuroprotective effects of Activin A on endoplasmic reticulum stress-mediated apoptotic and autophagic PC12 cell death.

Activin A, a member of the transforming growth factor-beta superfamily, plays a neuroprotective role in multiple neurological diseases. Endoplasmic reticulum (ER) stress-mediated apoptotic and autophagic cell death is implicated in a wide range of diseases, including cerebral ischemia and neurodegenerative diseases. Thapsigargin was used to induce PC12 cell death, and Activin A was used for intervention. Our results showed that Activin A significantly inhibited morphological changes in thapsigargin-induced apoptotic cells, and the expression of apoptosis-associated proteins [cleaved-caspase-12, C/EBP homologous protein (CHOP) and cleaved-caspase-3] and biomarkers of autophagy (Beclin-1 and light chain 3), and downregulated the expression of thapsigargin-induced ER stress-associated proteins [inositol requiring enzyme-1 (IRE1), tumor necrosis factor receptor-associated factor 2 (TRAF2), apoptosis signal-regulating kinase 1 (ASK1), c-Jun N-terminal kinase (JNK) and p38]. The inhibition of thapsigargin-induced cell death was concentration-dependent. These findings suggest that administration of Activin A protects PC12 cells against ER stress-mediated apoptotic and autophagic cell death by inhibiting the activation of the IRE1-TRAF2-ASK1-JNK/p38 cascade.

Activin A/Smads signaling pathway negatively regulates Oxygen Glucose Deprivation-induced autophagy via suppression of JNK and p38 MAPK pathways in neuronal PC12 cells.

Activin A (Act A), a member of the transforming growth factor-beta (TGF-ß), reduces neuronal apoptosis during cerebral ischemia through Act A/Smads signaling pathway. However, little is known about the effect of Act A/Smads pathway on autophagy in neurons. Here, we found that oxygen-glucose deprivation (OGD)-induced autophagy was suppressed by exogenous Act A in a concentration-dependent manner and enhanced by Act A/Smads pathway inhibitor (ActRIIA-Ab) in neuronal PC12 cells. These results indicate that Act A/Smads pathway negatively regulates autophagy in OGD-treated PC12 cells. In addition, we found that c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein (MAP) kinase pathways are involved in the OGD-induced autophagy. The activation of JNK and p38 MAPK pathways in OGD-treated PC12 cells was suppressed by exogenous Act A and enhanced by ActRIIA-Ab. Together, our results suggest that Act A/Smads signaling pathway negatively regulates OGD-induced autophagy via suppression of JNK and p38 MAPK pathways in neuronal PC12 cells.

Noncanonical Activin A Signaling in PC12 Cells: A Self-Limiting Feedback Loop.

Activin A (Act A), a member of transforming growth factor-ß superfamily, plays a neuroprotective role in multiple neurological diseases through Act A/Smads signal activation. Traditionally, the up-regulation of Act A gene and extracellular Act A accumulation show the signal activation as a linear pathway. However, one of our discoveries indicated that Act A could lead a loop signaling in ischemic injury. To clarify the characteristic of this loop signaling in a non-pathological state, we up-regulated the expression of Act A, monitored extracellular Act A accumulation and examined the activity of Act A signaling, which was quantified by the expression of phosphorylated Smad3 and the fluorescence intensity of Smad4 in nuclei. The results demonstrated a noncanonical Act A signal loop with self-amplifying property in PC12 cells. Further, it showed self-limiting behavior due to temporary activation and spontaneous attenuation. This periodic behavior of Act A signal loop was found to be regulated by the level of Smad anchor for receptor activation (SARA). Moreover, increased activity of Act A signal loop could promote PC12 cell proliferation and enhance the survival rate of cells to Oxygen-Glucose Deprivation. These practical discoveries will bring new insight on the functional outcome of Act A signaling in neurological diseases by the further understanding: loop signaling.

The role of Rho/Rho-kinase pathway and the neuroprotective effects of fasudil in chronic cerebral ischemia.

The Rho/Rho-kinase signaling pathway plays an important role in cerebral ischemia/reperfusion injury. However, very few studies have examined in detail the changes in the Rho/Rho-kinase signaling pathway in chronic cerebral ischemia. In this study, rat models of chronic cerebral ischemia were established by permanent bilateral common carotid artery occlusion and intragastrically administered 9 mg/kg fasudil, a powerful ROCK inhibitor, for 9 weeks. Morris water maze results showed that cognitive impairment progressively worsened as the cerebral ischemia proceeded. Immunohistochemistry, semi-quantitative RT-PCR and western blot analysis showed that the expression levels of Rho-kinase, its substrate myosin-binding subunit, and its related protein alpha smooth muscle actin, significantly increased after chronic cerebral ischemia. TUNEL staining showed that chronic cerebral ischemia could lead to an increase in neuronal apoptosis, as well as the expression level of caspase-3 in the frontal cortex of rats subjected to chronic cerebral ischemia. Fasudil treatment alleviated the cognitive impairment in rats with chronic cerebral ischemia, and decreased the expression level of Rho-kinase, myosin-binding subunit and alpha smooth muscle actin. Furthermore, fasudil could regulate cerebral injury by reducing cell apoptosis and decreasing caspase-3 expression in the frontal cortex. These findings demonstrate that fasudil can protect against cognitive impairment induced by chronic cerebral ischemia via the Rho/Rho-kinase signaling pathway and anti-apoptosis mechanism.

Effectiveness and safety of warfarin and anti-platelet drugs for the primary prevention of stroke in patients with non-valvular atrial fibrillation: a meta-analysis.

OBJECTIVE: To evaluate the effectiveness and safety of warfarin and anti-platelet drugs as the primary approach to the prevention of stroke in patients with non-valvular atrial fibrillation (NVAF). METHODS: Three English databases (the Cochrane library, Embase, and Medline), and three Chinese databases (the Chinese Biomedical Literature Database, Chinese National Knowledge Infrastructure, and Chinese Periodical Full-text Database of Science and Technology) were searched to select potentially eligible studies published before May, 2014. The studies were randomized controlled trials (RCTs) that investigated the effectiveness and safety of using warfarin and anti-platelet drugs in preventing stroke in NVAF patients; The statistical analysis was performed using the Review Manager 5.2 software provided by the Cochrane Collaboration. RESULTS: nine articles were finally included. Compared with antiplatelet drugs, warfarin treatment significantly reduced the risk of stroke (OR = 0.62, 95% CI 0.50-05.77), systemic embolism events (OR = 0.49, 95% CI 0.31-0.77), ischemic stroke events (OR = 0.46, 95% CI 0.36-0.59), stroke-related disability or death events (OR = 0.66, 95% CI 0.52-0.84). Warfarin did not increase the incidence of All-cause death events (OR = 0.92, 95% CI 0.78-1.08), intracranial hemorrhage events (OR = 1.28, 95% CI 0.85-1.93), major hemorrhage events (OR = 1.01, 95% CI 0.79-1.29). CONCLUSIONS: This meta-analysis found that compared with antiplatelet drugs, warfarin treatment significantly reduced the risk of stroke, systemic embolism events, ischemic stroke events, stroke-related disability or death events. And warfarin did not increase the incidence of All-cause death events, intracranial hemorrhage events, major hemorrhage events.

Computer-Based Cognitive Programs for Improvement of Memory, Processing Speed and Executive Function during Age-Related Cognitive Decline: A Meta-Analysis.

BACKGROUND: Several studies have assessed the effects of computer-based cognitive programs (CCP) in the management of age-related cognitive decline, but the role of CCP remains controversial. Therefore, this systematic review evaluated the evidence on the efficacy of CCP for age-related cognitive decline in healthy older adults. METHODS: Six electronic databases (through October 2014) were searched. The risk of bias was assessed using the Cochrane Collaboration tool. The standardized mean difference (SMD) and 95% confidence intervals (CI) of a random-effects model were calculated. The heterogeneity was assessed using the Cochran Q statistic and quantified with the I2 index. RESULTS: Twelve studies were included in the current review and were considered as moderate to high methodological quality. The aggregated results indicate that CCP improves memory performance (SMD, 0.31; 95% CI 0.16 to 0.45; p < 0.0001) and processing speed (SMD, 0.50; 95% CI 0.14 to 0.87; p = 0.007) but not executive function (SMD, -0.12; 95% CI -0.33 to 0.09; p = 0.27). Furthermore, there were long-term gains in memory performance (SMD, 0.59; 95% CI 0.13 to 1.05; p = 0.01). CONCLUSION: CCP may be a valid complementary and alternative therapy for age-related cognitive decline, especially for memory performance and processing speed. However, more studies with longer follow-ups are warranted to confirm the current findings.