Transient Cerebral Ischemia Alters GSK-3β and p-GSK-3β Immunoreactivity in Pyramidal Neurons and Induces p-GSK-3β Expression in Astrocytes in the Gerbil Hippocampal CA1 Area

New insights into the role of GSK-3β in the brain: from neurodegenerative disease to tumorigenesis

Glycogen synthase kinase 3 (GSK-3) is a serine/threonine kinase widely expressed in various tissues and organs. Unlike other kinases, GSK-3 is active under resting conditions and is inactivated upon stimulation. In mammals, GSK-3 includes GSK-3 α and GSK-3β isoforms encoded by two homologous genes, namely, GSK3A and GSK3B. GSK-3β is essential for the control of glucose metabolism, signal transduction, and tissue homeostasis. As more than 100 known proteins have been identified as GSK-3β substrates, it is sometimes referred to as a moonlighting kinase. Previous studies have elucidated the regulation modes of GSK-3β. GSK-3β is involved in almost all aspects of brain functions, such as neuronal morphology, synapse formation, neuroinflammation, and neurological disorders. Recently, several comparatively specific small molecules have facilitated the chemical manipulation of this enzyme within cellular systems, leading to the discovery of novel inhibitors for GSK-3β. Despite these advancements, the therapeutic significance of GSK-3β as a drug target is still complicated by uncertainties surrounding the potential of inhibitors to stimulate tumorigenesis. This review provides a comprehensive overview of the intricate mechanisms of this enzyme and evaluates the existing evidence regarding the therapeutic potential of GSK-3β in brain diseases, including Alzheimer's disease, Parkinson's disease, mood disorders, and glioblastoma.

Perillaldehyde improves diabetic cardiomyopathy by upregulating miR-133a-3p to regulate GSK-3β

Diabetic cardiomyopathy (DCM) is part of the most important causes of death from cardiovascular disease. Perillaldehyde (PAE), a major component of the herb perilla, has been shown to ameliorate doxorubicin-induced cardiotoxicity, but it is unclear whether PAE exerts beneficial effects on DCM. Exploring the potential molecular mechanisms of PAE for the treatment of DCM through network pharmacology and molecular docking. The SD rat type 1 diabetes model was established by a single intraperitoneal injection of streptozotocin (60 mg/kg), the cardiac function indexes of each group were detected by echocardiography; the morphological changes, apoptosis, protein expression of P-GSK-3β (S9), collagen I (Col-Ⅰ), collagen III (Col-Ⅲ) and alpha-smooth muscle actin (α-SMA), and miR-133a-3p expression levels were detected. An DCM model of H9c2 cells was established in vitro and transfected with Mimic and Inhibitor of miR-133a-3p. The results showed that PAE ameliorated cardiac dysfunction, reduced fasting glucose and cardiac weight index, and improved myocardial injury and apoptosis in DCM rats. It reduced high glucose-induced apoptosis, promoted migration and improved mitochondrial division injury in H9c2 cells. PAE decreased P-GSK-3β (S9), Col-Ⅰ, Col-Ⅲ and α-SMA protein expression and upregulated miR-133a-3p expression levels. After miR-133a-3p Inhibitor treatment, the expression of P-GSK-3β (S9) and α-SMA expression were significantly increased; after miR-133a-3p Mimic treatment, the expression of P-GSK-3β (S9) and α-SMA decreased significantly in H9c2 cells. It suggests that the mechanism of action of PAE to improve DCM may be related to the upregulation of miR-133a-3p and inhibition of P-GSK-3β expression.

Kaempferol Protects Against Cerebral Ischemia Reperfusion Injury Through Intervening Oxidative and Inflammatory Stress Induced Apoptosis

The aim of this research is to investigate the potential neuro-protective effect of kaempferol which with anti-oxidant, anti-inflammatory, and immune modulatory properties, and understand the effect of kaempferol on reducing cerebral ischemia reperfusion (I/R) injury in vivo. Male adult Sprague Dawley (SD) rats were pretreated with kaempferol for one week via gavage before cerebral I/R injury operation. We found that kaempferol treatment can reduce the cerebral infarct volume and neurological score after cerebral I/R. Rats were sacrificed after 24 h reperfusion. We observed that kaempferol improved the arrangement, distribution, and morphological structure of neurons, as well as attenuated cell apoptosis in brain tissue via hematoxylin and eosin (H&E) staining, Nissl staining and TUNEL staining. Superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH) kit analysis, enzyme-linked immunosorbent (ELISA) assay, real-time PCR, Western blot, and immunohistochemical examination indicated that kaempferol mitigated oxidative and inflammatory stress via regulating the expression of proteins, p-Akt, p-GSK-3β, nuclear factor erythroid2-related factor 2 (Nrf-2), and p-NF-κB during cerebral I/R, thus increasing the activity of SOD and GSH, meanwhile decreasing the content of MDA in serum and brain tissue, as well as restoring the expression levels of tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), and IL-6 in vivo. Taken together, this study suggested that kaempferol protects against cerebral I/R induced brain damage. The possible mechanism is related with inhibiting oxidative and inflammatory stress induced apoptosis.

Asiaticoside nitric oxide gel accelerates diabetic cutaneous ulcers healing by activating Wnt/β-catenin signaling pathway

Diabetic ulcers, gangrene, local infections and other traumatic symptoms of wound healing are all directly related. Promoting the early healing of diabetic cutaneous ulcers (DCU) and reducing the disability and treatment costs is an important research project integrating traditional Chinese and Western medicine. Nitric oxide (NO) is a key component of wound healing, and endogenous NO secretion is insufficient during the development of DCU. It has been reported that exogenous NO can promote wound healing, but exogenous NO has a short half-life and is difficult to adhere to the skin. Asiaticoside (AC) is extracted from the traditional Chinese medicine Centella asiatica, and has angiogenic, anticancer, antioxidant, anti-inflammatory, and wound-healing effects. Therefore, our study is based on the hypothesis that the combination of AC and NO to treat DCU is possible. In this study we considered gels of AC and NO, and evaluated the effects of the gel on DCU healing. Based on our study, it was found that the combined effect of asiaticoside and NO could accelerate the healing rate of DCU wounds. The asiaticoside NO gel can inhibit the growth of bacteria in the wound surface, alleviate the inflammatory reaction of wound, and increase the expression of VEGF, iNOS, eNOS and CD34. Our research shows that asiaticoside NO gel may promote DCU wound healing by regulating Wnt/β-Catenin signaling pathway. It will provide new targets and strategies for the diagnosis and treatment of DCU.

Analysis of knowledge bases and research focuses of cerebral ischemia-reperfusion from the perspective of mapping knowledge domain

Cerebral ischemia-reperfusion (IR) has attracted wide attention as a serious clinical problem. So far, the field has accumulated a large amount of scientific research literature. To clarify the temporal and spatial distribution characteristics of research resources, knowledge bases and research focuses, a visual analysis was performed on 5814 articles cited in the WoS databases from 2004 to 2019. This analysis was based on bibliometrics and mapping knowledge domain (MKD) analysis with VOSviewer, and CiteSpace 5.4.R4. The results can be elaborated from four aspects. First, the volume of publications in this area is on the rise. Second, the United States and China are the active regions. The USA is the central region of cerebral ischemia-reperfusion research. Third, the knowledge bases of IR have focused on five major areas of "Suitable small-animal models", "A framework with further study", "Molecular signaling targets by oxidative stress", "Finding new potential targets for therapy" and "Protective effect of multiple transient ischemia". Fourth, the research focuses consist of three representative areas: "Oxidative stress closelyd with cerebral ischemia-reperfusion", "Neuronal apoptosis and neuronal protection", and "Neuroprotective effect of the blood-brain barrier".

Inhibition of PDE4 protects neurons against oxygen-glucose deprivation-induced endoplasmic reticulum stress through activation of the Nrf-2/HO-1 pathway

Inhibition of phosphodiesterase 4 (PDE4) produces neuroprotective effects against cerebral ischemia. However, the involved mechanism remains unclear. Augmentation of endoplasmic reticulum (ER) stress promotes neuronal apoptosis, and excessive oxidative stress is an inducer of ER stress. The present study aimed to determine whether suppression of ER stress is involved in the protective effects of PDE4 inhibition against cerebral ischemia. We found that exposing HT-22 cells to oxygen-glucose deprivation (OGD) significantly activated ER stress, as evidenced by increased expression of the 78-kDa glucose-regulated protein (GRP78), phosphorylated eukaryotic translation-initiation factor 2α (eIF2α), and C/EBP-homologous protein (CHOP). Overexpression of PDE4B increased ER stress, while knocking down PDE4B or treatment with the PDE4 inhibitor, FCPR03, prevented OGD-induced ER stress in HT-22 cells. Furthermore, FCPR03 promoted the translocation of nuclear factor erythroid 2-related factor 2 (Nrf-2) from the cytoplasm to the nucleus. Importantly, the Nrf-2 inhibitor, ML385, blocked the inhibitory role of FCPR03 on OGD-induced ER stress. ML385 also abolished the protective role of FCPR03 in HT-22 cells subjected to OGD. Knocking down heme oxygenase-1 (HO-1), which is a target of Nrf-2, also blocked the protective role of FCPR03, enhanced the level of reactive oxygen species (ROS), and increased ER stress and cell death. We then found that FCPR03 or the antioxidant, N-Acetyl-l-cysteine, reduced oxidative stress in cells exposed to OGD. This effect was accompanied by increased cell viability and decreased ER stress. In primary cultured neurons, we found that FCPR03 reduced OGD-induced production of ROS and phosphorylation of eIF2α. The neuroprotective effect of FCPR03 against OGD in neurons was blocked by ML385. These results demonstrate that inhibition of PDE4 activates Nrf-2/HO-1, attenuates the production of ROS, and thereby attenuates ER stress in neurons exposed to OGD. Additionally, we conclude that FCPR03 may represent a promising therapeutic agent for the treatment of ER stress-related disorders.

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Overexpression of PDE4 increased ER stress under both basal and OGD conditions.

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Inhibition of PDE4 reduced ER stress and neuronal apoptosis in neurons exposed to OGD.

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PDE4 inhibition activated Nrf-2, and increased the level of antioxidant enzyme HO-1.

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Inhibition of Nrf-2 attenuated the role of FCPR03 on ER stress and cell viability.

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HO-1 knockdown abolished the effects of FCPR03 on ER stress and ROS production.

Dexamethasone induces osteoblast apoptosis through ROS-PI3K/AKT/GSK3β signaling pathway

BACKGROUND

Osteoblasts play important roles in the process of osteogenesis and prevention of osteonecrosis. Dexamethasone (Dex), a type of glucocorticoids (GCs), induces apoptosis of osteoblasts and leads to the occurrence of non-traumatic osteonecrosis. This study aimed to explore the effects of phosphatidylinositol 3-kinase/Protein kinase 3 (PI3K/AKT) and glycogen synthase kinase 3β (GSK3β) on Dex-induced osteoblasts apoptosis.

METHODS

Viabilities, proliferation, and apoptosis of primary osteoblasts and pre-osteoblast MC3T3-E1 cells after Dex treatment were detected using cell counting kit-8 (CCK-8) assay, 5-bromo-2'-deoxyuridine (BrdU) incorporation assay, FITC-Annexin V/PI staining and western blotting, respectively. 2',7'-Dichlorodihydrofluorescein diacetate (DCFH-DA) staining was performed to measure the intracellular reactive oxygen species (ROS) levels after Dex treatment. N-acetyl-l-cysteine (NAC) was used as ROS scavenger in this research. The expressions of PI3K/AKT and GSK3β in osteoblasts and MC3T3-E1 cells after Dex treatment were analyzed using western blotting and qRT-PCR, respectively. Then the effects of GSK3β knockdown on Dex-induced apoptosis of osteoblasts were explored. Alkaline phosphatase (ALP) activity assay was used to detect the role of Dex in regulating ALP activity.

RESULTS

Dex remarkably inhibited proliferation and induced apoptosis of osteoblasts and MC3T3-E1 cells. Dex potentially attenuated the osteoblast differentiation. The intracellular ROS levels were significantly increased after Dex treatment. Dex suppressed the activation of PI3K/AKT pathway in osteoblasts and MC3T3-E1 cells by down-regulating the expressions of p-PI3K and p-AKT. The expressions of GSK3β in osteoblasts and MC3T3-E1 cells were obviously up-regulated after Dex treatment. Knockdown of GSK3β alleviated Dex-induced osteoblast and MC3T3-E1 cell apoptosis by decreasing the expressions of Bax, cleaved-caspase 3, cleaved-caspase 9 and increasing the expression of Bcl-2.

CONCLUSION

Our research verified that Dex induced osteoblasts apoptosis by ROS-PI3K/AKT/GSK3β signaling pathway.

Time-Course Changes and New Expressions of MIP-3α and Its Receptor, CCR6, in the Gerbil Hippocampal CA1 Area Following Transient Global Cerebral Ischemia

Macrophage inflammatory protein-3α (MIP-3α) and its sole receptor, CCR6, play pivotal roles in neuroinflammatory processes induced by brain ischemic insults. In this study, we investigated transient ischemia-induced changes in MIP-3α and CCR6 protein expressions in the hippocampal CA1 area following 5 min of transient global cerebral ischemia (tgCI) in gerbils. Both MIP-3α and CCR6 immunoreactivities were very strongly expressed in pyramidal neurons of the CA1 area from 6 h to 1 day after tgCI and were hardly shown 4 days after tgCI. In addition, strong MIP-3α immunoreactivity was newly expressed in astrocytes 6 h after tgCI. These results indicate that tgCI causes apparent changes in MIP-3α and CCR6 expressions in pyramidal neurons and astrocytes in the hippocampal CA1 area and suggest that tgCI-induced changes in MIP-3α and CCR6 expressions might be closely associated with neuroinflammatory processes in brain ischemic regions.