Up-regulation of Bcl-2 in APP transgenic mice is associated with neuroprotection

Anthocyanin-Rich Fraction of Black Rice Bran Extract Protects against Amyloid β-Induced Oxidative Stress, Endoplasmic Reticulum Stress, and Neuronal Apoptosis in SK-N-SH Cells

Alzheimer's disease (AD) is the most common neurodegenerative disorder in the aging population. An accumulation of amyloid plaques and neurofibrillary tangles causes degeneration of neurons, leading to neuronal cell death. The anthocyanin-rich fraction of black rice (Oryza sativa L. variety "Luem Pua") bran (AFBRB), extracted using a solution of ethanol and water and fractionated using Amberlite XAD7HP column chromatography, contains a high anthocyanin content (585 mg of cyanidin-3-O-glucoside and 24 mg of peonidin-3-O-glucoside per gram of the rich extract), which has been found to reduce neurodegeneration. This study focused on the neuroprotective effects of AFBRB in Aβ25-35-induced toxicity in the human neuroblastoma cell line (SK-N-SH). SK-N-SH was exposed to Aβ25-35 (10 µM) to induce an AD cell model in vitro. Pretreatment with AFBRB (0.1, 1, or 10 µg/mL) or C3G (20 µM) was conducted for 2 h prior to the treatment with Aβ25-35 (10 µM) for an additional 24 h. The results indicate that AFBRB can protect against the cytotoxic effect of Aβ25-35 through attenuation of intracellular ROS production, downregulation of the expression of the proteins Bax, cytochrome c, cleaved caspase-9, and cleaved caspase-3, upregulation of the expression of Bcl-2 in the mitochondrial death pathway, and reduction in the expression of the three major markers of ER stress pathways in similar ways. Interestingly, we found that pretreatment with AFBRB significantly alleviated Aβ-induced oxidative stress, ER stress, and apoptosis in SK-N-SH cells. This suggests that AFBRB might be a potential therapeutic agent in preventing neurodegenerative diseases.

Amorfrutin B Compromises Hypoxia/Ischemia-induced Activation of Human Microglia in a PPARγ-dependent Manner: Effects on Inflammation, Proliferation Potential, and Mitochondrial Status

Amorfrutin B is a selective PPARγ modulator that we demonstrated to be a promising neuroprotective compound in cellular models of stroke and perinatal asphyxia. Although neuronal mechanisms of amorfrutin B-evoked neuroprotection have been identified, none of them reflects the actions of the compound on microglia, which play a pivotal role in brain response to hypoxia/ischemia. Here, we provide evidence for amorfrutin B-induced effects on human microglia subjected to hypoxia/ischemia; the compound counteracts inflammation, and influences mitochondrial status and proliferation potential in a PPARγ-dependent manner. Post-treatment with amorfrutin B decreased the IBA1 fluorescence intensity, reduced caspase-1 activity, and downregulated IL1B/IL-1β and TNFA but not IL10/IL-10 expression, which was upregulated. Amorfrutin B also stimulated PPARγ signaling, as evidenced by increased mRNA and/or protein levels of PPARγ and PGC1α. In addition, amorfrutin B reversed the hypoxia/ischemia-evoked effects on mitochondria-related parameters, such as mitochondrial membrane potential, BCL2/BCL2 expression and metabolic activity, which were correlated with diminished proliferation potential of microglia. Interestingly, the inhibitory effect of amorfrutin B on the proliferation potential and mitochondrial function of microglia is opposite to the stimulatory effect of amorfrutin B on mouse neuronal survival, as evidenced by increased neuronal viability and reduced neurodegeneration. In summary, this study showed for the first time that amorfrutin B compromises hypoxia/ischemia-induced activation of human microglia in a PPARγ-dependent manner, which involves inhibiting inflammation, normalizing mitochondrial status, and controlling proliferation potential. These data extend the protective potential of amorfrutin B in the pharmacotherapy of hypoxic/ischemic brain injury, targeting not only neurons but also activated microglia.

Sarcococca saligna ameliorated D-galactose induced neurodegeneration through repression of neurodegenerative and oxidative stress biomarkers

Sarcococca saligna is a valuable source of bioactive secondary metabolites exhibiting antioxidant, anti-inflammatory and acetylcholinesterase inhibitory activities. The study was intended to explore the therapeutic pursuits of S. saligna in amelioration of cognitive and motor dysfunctions induced by D-galactose and linked mechanistic pathways. Alzheimer's disease model was prepared by administration of D-galactose subcutaneous injection100 mg/kg and it was treated with rivastigmine (100 mg/kg, orally) and plant extract for 42 days. Cognitive and motor functions were evaluated by behavioral tasks and oxidative stress biomarkers. Level of acetylcholinesterase, reduced level of glutathione, protein and nitrite level, and brain neurotransmitters were analyzed in brain homogenate. The level of apoptosis regulator Bcl-2, Caspases 3 and heat shock protein HSP-70 in brain homogenates were analyzed by ELISA and colorimetric method, respectively. AChE, IL-1β, TNF-α, IL-1α and β secretase expressions were analyzed by RT-PCR. S. saligna dose dependently suppressed the neurodegenerative effects of D-galactose induced behavioral and biochemical impairments through modulation of antioxidant enzymes and acetylcholinesterase inhibition. S. saligna markedly (P < 0.05) ameliorated the level of brain neurotransmitters, Bcl-2, HSP-70 and Caspases-3 level. S. saligna at 500-1000 mg/kg considerably recovered the mRNA expression of neurodegenerative and neuro-inflammatory biomarkers, also evident from histopathological analysis. These findings suggest that S. saligna could be applicable in cure of Alzheimer's disease.

NMDA receptor antagonists reduce amyloid-β deposition by modulating calpain-1 signaling and autophagy, rescuing cognitive impairment in 5XFAD mice

Overstimulation of N-methyl-d-aspartate receptors (NMDARs) is the leading cause of brain excitotoxicity and often contributes to neurodegenerative diseases such as Alzheimer’s Disease (AD), the most common form of dementia. This study aimed to evaluate a new NMDA receptor antagonist (UB-ALT-EV) and memantine in 6-month-old female 5XFAD mice that were exposed orally to a chronic low-dose treatment. Behavioral and cognitive tests confirmed better cognitive performance in both treated groups. Calcium-dependent protein calpain-1 reduction was found after UB-ALT-EV treatment but not after memantine. Changes in spectrin breakdown products (SBDP) and the p25/p35 ratio confirmed diminished calpain-1 activity. Amyloid β (Aβ) production and deposition was evaluated in 5XFAD mice and demonstrated a robust effect of NMDAR antagonists on reducing Aβ deposition and the number and size of Thioflavin-S positive plaques. Furthermore, glycogen synthase kinase 3β (GSK3β) active form and phosphorylated tau (AT8) levels were diminished after UB-ALT-EV treatment, revealing tau pathology improvement. Because calpain-1 is involved in autophagy activation, autophagic proteins were studied. Strikingly, results showed changes in the protein levels of unc-51-like kinase (ULK-1), beclin-1, microtubule-associated protein 1A/1B-light chain 3(LC3B-II)/LC3B-I ratio, and lysosomal-associated membrane protein 1 (LAMP-1) after NMDAR antagonist treatments, suggesting an accumulation of autophagolysosomes in 5XFAD mice, reversed by UB-ALT-EV. Likewise, treatment with UB-ALT-EV recovered a WT mice profile in apoptosis markers Bcl-2, Bax, and caspase-3. In conclusion, our results revealed the potential neuroprotective effect of UB-ALT-EV by attenuating NMDA-mediated apoptosis and reducing Aβ deposition and deposition jointly with the autophagy rescue to finally reduce cognitive alterations in a mice model of familial AD.

The role of Bcl-2 proteins in modulating neuronal Ca2+ signaling in health and in Alzheimer's disease

The family of B-cell lymphoma-2 (Bcl-2) proteins exerts key functions in cellular health. Bcl-2 primarily acts in mitochondria where it controls the initiation of apoptosis. However, during the last decades, it has become clear that this family of proteins is also involved in controlling intracellular Ca2+ signaling, a critical process for the function of most cell types, including neurons. Several anti- and pro-apoptotic Bcl-2 family members are expressed in neurons and impact neuronal function. Importantly, expression levels of neuronal Bcl-2 proteins are affected by age. In this review, we focus on the emerging roles of Bcl-2 proteins in neuronal cells. Specifically, we discuss how their dysregulation contributes to the onset, development, and progression of neurodegeneration in the context of Alzheimer's disease (AD). Aberrant Ca2+ signaling plays an important role in the pathogenesis of AD, and we propose that dysregulation of the Bcl-2-Ca2+ signaling axis may contribute to the progression of AD and that herein, Bcl-2 may constitute a potential therapeutic target for the treatment of AD.

Selective Targeting of Non-nuclear Estrogen Receptors with PaPE-1 as a New Treatment Strategy for Alzheimer's Disease

Alzheimer’s disease (AD) is a multifactorial and severe neurodegenerative disorder characterized by progressive memory decline, the presence of Aβ plaques and tau tangles, brain atrophy, and neuronal loss. Available therapies provide moderate symptomatic relief but do not alter disease progression. This study demonstrated that PaPE-1, which has been designed to selectively activate non-nuclear estrogen receptors (ERs), has anti-AD capacity, as evidenced in a cellular model of the disease. In this model, the treatment of mouse neocortical neurons with Aβ (5 and 10 μM) induced apoptosis (loss of mitochondrial membrane potential, activation of caspase-3, induction of apoptosis-related genes and proteins) accompanied by increases in levels of reactive oxygen species (ROS) and lactate dehydrogenase (LDH) as well as reduced cell viability. Following 24 h of exposure, PaPE-1 inhibited Aβ-evoked effects, as shown by reduced parameters of neurotoxicity, oxidative stress, and apoptosis. Because PaPE-1 downregulated Aβ-induced Fas/FAS expression but upregulated that of Aβ-induced FasL, the role of PaPE-1 in controlling the external apoptotic pathway is controversial. However, PaPE-1 normalized Aβ-induced loss of mitochondrial membrane potential and restored the BAX/BCL2 ratio, suggesting that the anti-AD capacity of PaPE-1 particularly relies on inhibition of the mitochondrial apoptotic pathway. These data provide new evidence for an anti-AD strategy that utilizes the selective targeting of non-nuclear ERs with PaPE-1.

Calcium-Handling Defects and Neurodegenerative Disease

Calcium signaling is critical to neuronal function and regulates highly diverse processes such as gene transcription, energy production, protein handling, and synaptic structure and function. Because there are many common underlying calcium-mediated pathological features observed across several neurological conditions, it has been proposed that neurodegenerative diseases have an upstream underlying calcium basis in their pathogenesis. With certain diseases such as Alzheimer's, Parkinson's, and Huntington's, specific sources of calcium dysregulation originating from distinct neuronal compartments or channels have been shown to have defined roles in initiating or sustaining disease mechanisms. Herein, we will review the major hallmarks of these diseases, and how they relate to calcium dysregulation. We will then discuss neuronal calcium handling throughout the neuron, with special emphasis on channels involved in neurodegeneration.

Preserving Lysosomal Function in the Aging Brain: Insights from Neurodegeneration

Lysosomes are acidic, membrane-bound organelles that serve as the primary catabolic compartment of the cell. They are crucial to a variety of cellular processes from nutrient storage to autophagy. Given the diversity of lysosomal functions, it is unsurprising that lysosomes are also emerging as important players in aging. Lysosomal dysfunction is implicated in several aging-related neurodegenerative diseases including Alzheimer's, Parkinson's, amyotrophic lateral sclerosis/frontotemporal dementia, and Huntington's. Although the precise role of lysosomes in the aging brain is not well-elucidated, some insight into their function has been gained from our understanding of the pathophysiology of age-dependent neurodegenerative diseases. Therapeutic strategies targeting lysosomes and autophagic machinery have already been tested in several of these diseases with promising results, suggesting that improving lysosomal function could be similarly beneficial in preserving function in the aging brain.

miR-124 downregulates BACE 1 and alters autophagy in APP/PS1 transgenic mice

One role of BACE 1 (Beta-site amyloid precursor protein cleaving enzyme 1) is to cleave the sequential amyloid precursor protein (APP) into β-Amyloid (Aβ), the accumulation of which is an important participant in the formation of the amyloid plaques and neurofibrillary tangles of Alzheimer's disease (AD). Our previous study showed BACE 1, the potential functional downstream target of miR-124, to be connected to cell death in AD cell models. Recent studies have shown that autophagy is altered in AD, however, as to whether miR-124 is involved in this alteration is not clear. In this study, 7-month-old APP/PS1 transgenic mice were transfected with miR-124 lentiviral vectors, injected bilaterally into the dentate gyrus (DG) of mice hippocampi. Following 7 days of recovery, both behavior and biochemical pathology tests were implemented. The results demonstrated learning ability improvement and specific AD pathology alleviation. Meanwhile there was down-regulation of Bcl-2 to Bax ratio expression, increase in Beclin-1 and decreases in expression of LC3II, Atg5 and p62/SQSTMl. In view of this, we hypothesis that miR-124 conducts its neuroprotective effect through BACE 1 by regulation of autophagic pathways.

Effects of sodium ferulate on preventing steroid-induced femoral head osteonecrosis in rabbits

The aim of this study is to investigate the effects and possible mechanisms of sodium ferulate (SF) on anti-apoptosis in steroid-induced femoral head osteonecrosis in rabbits. Japanese white rabbits were randomly divided into three groups (control group, treatment group, and model group), each with 24 rabbits. The model and treatment groups were first injected with an intravenous dose of horse serum, 10 ml/kg, three weeks later with an intravenous dose of 7.5 ml/kg, and two weeks later with an intramuscular dose of methylprednisolone, 45 mg/kg, three times in order to establish rabbit models of osteonecrosis. Concurrently, the treatment group was injected with intravenous doses of SF 20 mg/kg for two weeks, once per day. Three time points, Weeks 2, 4, and 8, were selected after modeling was completed. Osteonecrosis was verified by histopathology with haematoxylin-eosin (HE) staining. The apoptosis rate of osteonecrosis was observed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The apoptosis expressions of caspase-3 and Bcl-2 were analyzed by immunohistochemistry and Western blot. The rabbit models of osteonecrosis were successfully established and observed by HE staining. SF was effective in intervening in apoptosis and decreasing the apoptosis rate in femoral head necrosis by the immunohistochemistry and TUNEL assay (P<0.01). Western blot analysis indicated that there were statistical significances in the protein levels of caspase-3 and Bcl-2 (P<0.01). SF has a protective effect by reducing the incidence of early steroid-induced femoral head necrosis in rabbits, effectively intervening in apoptosis through decreasing caspase-3 expression and up-regulating Bcl-2 expression.

Antitumor effect and mechanism of an ellagic acid derivative on the HepG2 human hepatocellular carcinoma cell line

In the present study, to identify the effective components of Chinese traditional herbs, Euphorbia hylonoma Hand.-Mazz. (Euphorbiaceae), a folk herb that has been used among the Qinling mountain area for hundreds of years, was investigated. 3,3′-Di-O-methyl ellagic acid-4′-O-β-d-xylopyranoside (JNE2), an ellagic acid derivative, was isolated from the acetone extract of the herb and its antitumor activity against human hepatoma HepG2 cells was detected in vitro. The results showed that JNE2 inhibited the proliferation of HepG2 cells in a dose- and time-dependent manner and blocked the cell cycle at the G1/S phase. A high dosage of JNE2 induced apoptosis of the tumor cells, but no significant differences were identified between the treatment groups. The invasiveness of HepG2 cells was also inhibited by JNE2. The mechanism of the antitumor effect of JNE2 at the molecular level was presumed to be due to the upregulation of the protein expression of Bax and caspase-3, and the downregulation of the protein expression of Bcl-2 and CCND1. The results suggested that JNE2 is a potential antitumor agent that merits further investigation.

Resveratrol attenuates brain damage in a rat model of focal cerebral ischemia via up-regulation of hippocampal Bcl-2

A number of studies have demonstrated that resveratrol (Res), a natural polyphenol compound found in plants, shows potent neuroprotective, anti-inflammatory and antioxidant effects; however, its ability to prevent ischemia-induced brain damage remains unclear. Here we tested whether Res played a neuroprotective role in a rat brain ischemia model induced by middle cerebral artery occlusion (MCAO). Adult male rats were randomly assigned into four experimental groups: sham operation (sham), ischemia treatment (MCAO), Res-treated MCAO (Res+MCAO) and Res alone group (Res+sham). The brain damage size and hippocampal apoptotic neurons in each rat were evaluated by triphenyltetrazolium chloride (TTC) staining and terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling (TUNEL) staining, respectively. Long-term potentiation (LTP) induced by high-frequency stimulation (HFS) in the hippocampus was assessed with extracellular recording. The expression of apoptosis-related proteins, i.e., Bcl-2 and Bax, in the hippocampus was detected by western blot. Our results revealed that Res treatment significantly reduced brain infarct volume of MCAO rats as compared to MCAO rats without Res treatment. A significant increase in TUNEL-positive neurons in the hippocampal CA1 region was visualized in the MCAO rats as compared to that of the sham group, but this increase was attenuated with Res treatment. Functionally, extracellular recordings revealed that MCAO operation impaired LTP in the hippocampal CA1 region and the basal synaptic transmission between the Schaffer collaterals, whereas Res treatment rescued the impaired LTP and facilitated synaptic transmission in the CA1 region of the MCAO rats. Res treatment increased the expression of anti-apoptotic protein Bcl-2 and decreased the expression of pro-apoptotic protein Bax in the MCAO rats. The findings suggest that Res can attenuate the deleterious effects of focal cerebral ischemia/reperfusion-induced brain injury and function as a potential neuroprotective agent. The neuroprotective qualities of Res, based on our data, may be attributable to the up-regulation of Bcl-2 expression and down-regulation of Bax expression.

Age-dependent accumulation of soluble amyloid beta (Abeta) oligomers reverses the neuroprotective effect of soluble amyloid precursor protein-alpha (sAPP(alpha)) by modulating phosphatidylinositol 3-kinase (PI3K)/Akt-GSK-3beta pathway in Alzheimer mouse model

Neurotrophins, activating the PI3K/Akt signaling pathway, control neuronal survival and plasticity. Alterations in NGF, BDNF, IGF-1, or insulin signaling are implicated in the pathogenesis of Alzheimer disease. We have previously characterized a bigenic PS1×APP transgenic mouse displaying early hippocampal Aβ deposition (3 to 4 months) but late (17 to 18 months) neurodegeneration of pyramidal cells, paralleled to the accumulation of soluble Aβ oligomers. We hypothesized that PI3K/Akt/GSK-3β signaling pathway could be involved in this apparent age-dependent neuroprotective/neurodegenerative status. In fact, our data demonstrated that, as compared with age-matched nontransgenic controls, the Ser-9 phosphorylation of GSK-3β was increased in the 6-month PS1×APP hippocampus, whereas in aged PS1×APP animals (18 months), GSK-3β phosphorylation levels displayed a marked decrease. Using N2a and primary neuronal cell cultures, we demonstrated that soluble amyloid precursor protein-α (sAPPα), the predominant APP-derived fragment in young PS1×APP mice, acting through IGF-1 and/or insulin receptors, activated the PI3K/Akt pathway, phosphorylated the GSK-3β activity, and in consequence, exerted a neuroprotective action. On the contrary, several oligomeric Aβ forms, present in the soluble fractions of aged PS1×APP mice, inhibited the induced phosphorylation of Akt/GSK-3β and decreased the neuronal survival. Furthermore, synthetic Aβ oligomers blocked the effect mediated by different neurotrophins (NGF, BDNF, insulin, and IGF-1) and sAPPα, displaying high selectivity for NGF. In conclusion, the age-dependent appearance of APP-derived soluble factors modulated the PI3K/Akt/GSK-3β signaling pathway through the major neurotrophin receptors. sAPPα stimulated and Aβ oligomers blocked the prosurvival signaling. Our data might provide insights into the selective vulnerability of specific neuronal groups in Alzheimer disease.

Deletion mutational analysis of BMRP, a pro-apoptotic protein that binds to Bcl-2

Bcl-2 is an anti-apoptotic member of the Bcl-2 family of proteins that protects cells from apoptosis induced by a large variety of stimuli. The protein BMRP (MRPL41) was identified as a Bcl-2 binding partner and shown to have pro-apoptotic activity. We have performed deletion mutational analyses to identify the domain(s) of Bcl-2 and BMRP that are involved in the Bcl-2/BMRP interaction, and the region(s) of BMRP that mediate its pro-apoptotic activity. The results of these studies indicate that both the BH4 domain of Bcl-2 and its central region encompassing its BH1, BH2, and BH3 domains are required for its interaction with BMRP. The loop region and the transmembrane domain of Bcl-2 were found to be dispensable for this interaction. The Bcl-2 deletion mutants that do not interact with BMRP were previously shown to be functionally inactive. Deletion analyses of the BMRP protein delimited the region of BMRP needed for its interaction with Bcl-2 to the amino-terminal two-thirds of the protein (amino acid residues 1-92). Further deletions at either end of the BMRP(1-92) truncated protein resulted in lack of binding to Bcl-2. Functional studies performed with BMRP deletion mutants suggest that the cell death-inducing domains of the protein reside mainly within its amino-terminal two-thirds. The region of BMRP required for the interaction with Bcl-2 is very relevant for the cell death-inducing activity of the protein, suggesting that one possible mechanism by which BMRP induces cell death is by binding to and blocking the anti-apoptotic activity of Bcl-2.

Single-prolonged stress induced mitochondrial-dependent apoptosis in hippocampus in the rat model of post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is a stress-related mental disorder caused by experience of a traumatic event, and presents with characteristic symptoms including intrusive memories, hyperarousal, and avoidance. Recently, structural neuroimaging studies showed that hippocampal volumes were relatively low in PTSD patients. However, the mechanisms that cause such atrophy are not well understood. The aim of this study was to reveal the possible mechanisms involved in apoptosis induced by single-prolonged stress (SPS) in hippocampus of PTSD rats. SPS is one of the animal models proposed for PTSD. Rats exposure to SPS showed enhanced inhibition of the hypothalamo-pituitary-adrenal (HPA) axis, which has been reliably reproduced in patients with PTSD. Wistar rats were killed at 1, 4, 7, 14 and 28 days after exposure to SPS. Expression of caspase-9, caspase-3, cytochrome c, Bcl-2 and Bax was detected by immunohistochemistry, immunofluorescence, Western blotting and electron microscopy. Apoptotic cells were assessed by TUNEL method. Our results showed apoptotic cells were significantly increased in hippocampus of SPS rats, accompanied by release of cytochrome c from the mitochondria into the cytosol, increase of caspase-9 and caspase-3 expression and decrease of the Bcl-2/Bax ratio. The results indicate that SPS-induced apoptosis in hippocampus of PTSD rats, and the mitochondrial pathway was involved in the process of SPS-induced apoptosis.

Changes of Bax, Bcl-2 and apoptosis in hippocampus in the rat model of post-traumatic stress disorder

OBJECTIVE

Post-traumatic stress disorder (PTSD) is a stress-related mental disorder caused by experience of a traumatic event. PTSD is often accompanied by morphological and functional changes in the hippocampus. Recently, it was reported that the hippocampal volumes of PTSD patients are relatively low. However, the mechanisms that cause such atrophy are not well understood. Single prolonged stress (SPS) is one of the animal models proposed for PTSD. The aim of this study was to reveal whether hippocampal neuronal apoptosis and the expression of apoptosis-related protein and gene occur and investigate behavioral and electrophysiological changes of hippocampi in SPS rats.

METHODS

Wistar rats were killed at 1, 4, 7, 14 and 28 days after exposure to SPS. The apoptotic cells were assessed by TUNEL method and transmission electron microscopy. Bax and Bcl-2 expression was detected by immunohistochemistry, immunofluorescence, western blotting and RT-PCR. Behavioral and electrophysiological alterations were detected by Morris water maze test and long-term potentiation (LTP) respectively.

RESULTS

Our results showed that apoptosis exactly occurred in hippocampus of SPS rats. Apoptotic cells reached peak level at 7 days after exposure to SPS. Both Bcl-2 and Bax were significantly up-regulated during early PTSD. Bcl-2 reached peak level at 4 days. Bax reached peak level at 7 days. Behavioral analyses revealed that the SPS rats exhibited obvious impaired spatial memory that paralleled the deficits in hippocampal LTP.

CONCLUSION

In conclusion, SPS caused a series of morphological and behavioral changes in hippocampus. Apoptosis may be one of the reasons inducing hippocampus atrophy. The changes of apoptosis-related proteins and genes of Bcl-2 and Bax might be involved in the early molecular regulatory mechanism of apoptosis in PTSD. The impaired LTP was related to apoptosis in the hippocampus of SPS rats. The mechanisms of apoptosis and impaired LTP might be involved in PTSD.

Selective induction of calcineurin activity and signaling by oligomeric amyloid beta

Alzheimer's disease (AD) is a terminal age-associated dementia characterized by early synaptic dysfunction and late neurodegeneration. Although the presence of plaques of fibrillar aggregates of the amyloid beta peptide (Abeta) is a signature of AD, evidence suggests that the preplaque small oligomeric Abeta promotes both synaptic dysfunction and neuronal death. We found that young Tg2576 transgenic mice, which accumulate Abeta and develop cognitive impairments prior to plaque deposition, have high central nervous system (CNS) activity of calcineurin (CaN), a phosphatase involved in negative regulation of memory function via inactivation of the transcription factor cAMP responsive element binding proteins (CREB), and display CaN-dependent memory deficits. These results thus suggested the involvement of prefibrillary forms of Abeta. To investigate this issue, we compared the effect of monomeric, oligomeric, and fibrillar Abeta on CaN activity, CaN-dependent pCREB and phosphorylated Bcl-2 Associated death Protein (pBAD) levels, and cell death in SY5Y cells and in rat brain slices, and determined the role of CaN on CREB phosphorylation in the CNS of Tg2576 mice. Our results show that oligomeric Abeta specifically induces CaN activity and promotes CaN-dependent CREB and Bcl-2 Asociated death Protein (BAD) dephosphorylation and cell death. Furthermore, Tg2576 mice display Abeta oligomers and reduced pCREB in the CNS, which is normalized by CaN inhibition. These findings suggest a role for CaN in mediating effects of oligomeric Abeta on neural cells. Because elevated CaN levels have been reported in the CNS of cognitively impaired aged rodents, our results further suggest that abnormal CaN hyperactivity may be a common event exacerbating the cognitive and neurodegenerative impact of oligomeric Abeta in the aging CNS.

Mechanisms of neuronal death in disease: defining the models and the players

Dysregulation of life and death at the cellular level leads to a variety of diseases. In the nervous system, aberrant neuronal death is an outstanding feature of neurodegenerative diseases. Since the discovery of the caspase family of proteases, much effort has been made to determine how caspases function in disease, including neurodegenerative diseases. Although many papers have been published examining caspases in neuronal death and disease, the pathways have not been fully clarified. In the present review, we examine the potential players in the death pathways, the current tools for examining these players and the models for studying neurological disease. Alzheimer's disease, the most common neurodegenerative disorder, and cerebral ischaemia, the most common cause of neurological death, are used to illustrate our current understanding of death signalling in neurodegenerative diseases. A better understanding of the neuronal death pathways would provide targets for the development of therapeutic interventions for these diseases.

Lack of pathology in a triple transgenic mouse model of Alzheimer's disease after overexpression of the anti-apoptotic protein Bcl-2

Alzheimer's disease (AD) is characterized by the accumulation of plaques containing beta-amyloid (Abeta) and neurofibrillary tangles (NFTs) consisting of modified tau. Although Abeta deposition is thought to precede the formation of NFTs in AD, the molecular steps connecting these two pathologies is not known. Previous studies have suggested that caspase activation plays an important role in promoting the pathology associated with AD. To further understand the contribution of caspases in disease progression, a triple transgenic Alzheimer's mouse model overexpressing the anti-apoptotic protein Bcl-2 was generated. Here we show that overexpression of Bcl-2 limited caspase-9 activation and reduced the caspase cleavage of tau. Moreover, overexpression of Bcl-2 attenuated the processing of APP (amyloid precursor protein) and tau and reduced the number of NFTs and extracellular deposits of Abeta associated with these animals. In addition, overexpression of Bcl-2 in 3xTg-AD mice improved place recognition memory. These findings suggest that the activation of apoptotic pathways may be an early event in AD and contributes to the pathological processes that promote the disease mechanisms underlying AD.

Induction of apoptosis in HepG2 cells by solanine and Bcl-2 protein

The nightshade (Solanum nigrum Linn.) has been widely used in Chinese traditional medicine as a remedy for the treatment of digestive system cancer. The anti-tumor activity of solanine, a steroid alkaloid isolated from the nightshade has been demonstrated. To observe the effect of anti-tumor and mechanism of solanine. The MTT assay was used to evaluate the IC(50) on the three digestive system tumor cell lines. The effect on the morphology was observed with a laser confocal microscopy; the rate of apoptosis and the cell cycle were measured using flow cytometry (FCM); the expression of Bcl-2 protein was measured by Western blot. The results show that the IC(50) for HepG(2), SGC-7901, and LS-174 were 14.47, >50, and >50 microg/ml, respectively; the morphology of cells in the negative control was normal; for the treated groups, typical signs for apoptosis were found. The rate of apoptosis in HepG(2) cells induced by solanine was found to be 6.0, 14.4, 17.3, 18.9, and 32.2%, respectively. Observation of the cell cycle showed that cells in the G(2)/M phases disappeared while the number of cells in the S phase increased significantly for treated groups. Western blot showed that solanine decreased the expression of Bcl-2 protein. Therefore, the target of solanine in inducing apoptosis in HepG(2) cells seems to be mediated by the inhibition in the expression of Bcl-2 protein.

Differential nigral expression of bcl-2 protein family in the pure and common forms of Dementia with Lewy bodies: relevance for dopaminergic neuronal vulnerability

We investigated whether bcl-2 protein family is involved in the pathogenesis of the dopaminergic neurodegeneration that occurs in Dementia with Lewy bodies (DLB). The expression of the proapoptotic protein bax and the antiapoptotic proteins bcl-2 and bcl-xL was investigated by Western blot in the pars compacta of the substantia nigra of pure and common DLB forms. No changes in the nigral expression levels of bax, bcl-2 and bcl-xL proteins were found between control and DLB pure cases. In the common DLB forms, nigral bcl-xL and bcl-2 proteins levels were significantly decreased in the DLB cases associated with a concomitant severe AD pathology (p < 0.05). An increase in nigral bcl-2 protein expression was observed in the DLB cases with a mild AD-associated pathology (p < 0.05). The present results are in agreement with previous observations indicating that DLB cases with severe AD pathology tend to show severe Lewy pathology suggesting that AD pathology might exacerbate Lewy pathology.

Altered levels and distribution of IGF-II/M6P receptor and lysosomal enzymes in mutant APP and APP + PS1 transgenic mouse brains

The insulin-like growth factor-II/mannose-6-phosphate (IGF-II/M6P) receptor participates in the trafficking of lysosomal enzymes from the trans-Golgi network or the cell surface to lysosomes. In Alzheimer's disease (AD) brains, marked up-regulation of the lysosomal system in vulnerable neuronal populations has been correlated with altered metabolic functions. To establish whether IGF-II/M6P receptors and lysosomal enzymes are altered in the brain of transgenic mice harboring different familial AD mutations, we measured the levels and distribution of the receptor and lysosomal enzymes cathepsins B and D in select brain regions of transgenic mice overexpressing either mutant presenilin 1 (PS1; PS1(M146L+L286V)), amyloid precursor protein (APP; APP(KM670/671NL+V717F)) or APP+PS1 (APP(KM670/671NL+V717F)+PS1(M146L+L286V)) transgenes. Our results revealed that levels and expression of the IGF-II/M6P receptor and lysosomal enzymes are increased in the hippocampus and frontal cortex of APP and APP+PS1, but not in PS1, transgenic mouse brains compared with wild-type controls. The changes were more prominent in APP+PS1 than in APP single transgenic mice. Additionally, all beta-amyloid-containing neuritic plaques in the hippocampal and cortical regions of APP and APP+PS1 transgenic mice were immunopositive for both lysosomal enzymes, whereas only a subset of the plaques displayed IGF-II/M6P receptor immunoreactivity. These results suggest that up-regulation of the IGF-II/M6P receptor and lysosomal enzymes in neurons located in vulnerable regions reflects an altered functioning of the endosomal-lysosomal system which may be associated with the increased intracellular and/or extracellular A beta deposits observed in APP and APP+PS1 transgenic mouse brains.