Down‐regulation of Bcl‐2 enhances autophagy activation and cell death induced by mitochondrial dysfunction in rat striatum

In vivo administration of the mitochondrial inhibitor 3‐nitropropionic acid (3‐NP) produces striatal pathology mimicking Huntington's disease (HD). However, the mechanisms of cell death induced by metabolic impairment are not fully understood. Previous studies showed that 3‐NP triggered p53‐depedent autophagy activation and cell death. The present study investigated the contribution of the Bcl‐2 signaling pathway to autophagy activation and cell death induced by 3‐NP. Rat striatum was intoxicated with 3‐NP by stereotaxic injection. 3‐NP up‐regulated the expression of the autophagic protein beclin 1 but down‐regulated the expression of the antiapoptotic protein Bcl‐2. Pretreatment with the autophagy inhibitor 3‐methyladenine (3‐MA) significantly inhibited the 3‐NP‐induced alterations in beclin 1 and Bcl‐2 protein levels. Similarly, the 3‐NP‐induced decline in Bcl‐2 was also prevented by the lysosomal inhibitor E64, indicating degradation of Bcl‐2 by lysosomes. In agreement with the time course of 3‐NP‐induced cell death, an increase in the release of cytochrome c from mitochondria was observed. 3‐MA also attenuated the 3‐NP‐induced release of cytochrome c. On the other hand, 3‐NP‐induced elevations in proapoptotic protein Bax and autophagic protein beclin 1 and LC3‐II were significantly enhanced by the Bcl‐2‐specific inhibitor HA14‐1. Furthermore, HA14‐1 increased the release of cytochrome c and 3‐NP‐induced striatal damage. These results suggest that induction of autophagy leads to degradation of Bcl‐2. Meanwhile, down‐regulation of Bcl‐2 amplifies autophagy activation and apoptotic signaling. Bcl‐2 thus plays important roles in mitochondria dysfunction‐induced apoptotic death of stritatal neurons by modulating both autophagic and apoptotic processes. © 2009 Wiley‐Liss, Inc.     

Lack of Oestrogenic Inhibition of the Nuclear Factor‐κB Pathway in Somatolactotroph Tumour Cells

Activation of nuclear factor (NF)‐κB promotes cell proliferation and inhibits apoptosis. We have previously shown that oestrogens sensitise normal anterior pituitary cells to the apoptotic effect of tumour necrosis factor (TNF)‐α by inhibiting NF‐κB nuclear translocation. In the present study, we examined whether oestrogens also modulate the NF‐κB signalling pathway and apoptosis in GH3 cells, a rat somatolactotroph tumour cell line. As determined by Western blotting, 17β‐oestradiol (E₂) (10^?9 m ) increased the nuclear concentration of NF‐κB/p105, p65 and p50 in GH3 cells. However, E₂ did not modify the expression of Bcl‐xL, a NF‐κB target gene. TNF‐α induced apoptosis of GH3 cells incubated in either the presence or absence of E₂. Inhibition of the NF‐kB pathway using BAY 11‐7082 (BAY) (5 μm ) decreased the viability of GH3 cells and increased the percentage of terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL)‐positive GH3 cells. BAY also increased TNF‐α‐induced apoptosis of GH3 cells, an effect that was further increased by an inhibitor of the c‐Jun N‐terminal protein kinase pathway, SP600125 (10 μm ). We also analysed the role of the NF‐κB signalling pathway on proliferation and apoptosis of GH3 tumours in vivo. The administration of BAY to nude mice bearing GH3 tumours increased the number of TUNEL‐positive cells and decreased the number of proliferating GH3 cells. These findings suggest that GH3 cells lose their oestrogenic inhibitory action on the NF‐κB pathway and that the pro‐apoptotic effect of TNF‐α on these tumour pituitary cells does not require sensitisation by oestrogens as occurs in normal pituitary cells. NF‐κB was required for the survival of GH3 cells, suggesting that pharmacological inhibition of the NF‐κB pathway could interfere with pituitary tumour progression.     

p53‐Induced Uncoupling Expression of Aquaporin‐4 and Inwardly Rectifying K+ 4.1 Channels in Cytotoxic Edema after Subarachnoid Hemorrhage

Aims: To investigate the mechanism behind cytotoxic edema formation following subarachnoid hemorrhage (SAH). Methods: We explored the role of aquaporin‐4 (AQP4), inwardly rectifying K⁺ 4.1 (Kir4.1) channels and their upstream orchestrators p53 and p38MAPK in this process. A p53 inhibitor, pifithrin‐α (PFT‐α) was administered intraperitoneally to rats undergoing SAH by endovascular perforation. Totally, 98 male SD rats were categorized into sham, SAH, SAH+ dimethyl sulfoxide (DMSO), SAH+ 0.2 or 2.0 mg/kg PFT‐α groups. At 24 h after SAH, MRI (diffusion‐weighted imaging [DWI]), immunohistochemistry, and Western blot were used. Results: MRI (DWI) showed a significant cytotoxic edema in the brain following SAH with PFT‐α therapy reducing it. Immunohistochemistry and Western blot showed an increased level of p53, phosphorylated‐p38MAPK and AQP4 and a reduced level of Kir4.1; all of which could be reversed following PFT‐α treatment. Treble labeling staining revealed colocalization of p53 with phosphorylated‐p38MAPK and unmatched expression of AQP4 and Kir4.1 within astrocyte cells. Conclusion: These results indicated p53 mediates the formation of cytotoxic edema in the brain following SAH; an uncoupling expression of AQP4 and Kir4.1 on astrocytic end feets orchestrated by p38MAPK was partly responsible.     

Autophagic induction of amyotrophic lateral sclerosislinked Cu/Zn superoxide dismutase 1 G93A mutant in NSC34 cells简

Previous studies have confirmed that the beclin 1 complex plays a key role in the initial stage of autophagy and deregulated autophagy might involve in amyotrophic lateral sclerosis. However, the mechanism underlying altered autophagy associated with the beclin 1 complex remains un- clear. In this study, we transfected the Cu/Zn superoxide dismutase 1 G93A mutant protein into the motor neuron-like cell line NSC34 cultured in vitro. Western blotting and co-immunopre- cipitation showed that the Cu/Zn superoxide dismutase 1 G93A mutant enhanced the turnover of autophagic marker microtubule-associated protein light chain 3II （LC3Ⅱ） and stimulated the conversion of EGFP-LC3Ⅰ to EGFP-LC3Ⅱ, but had little influence on the binding capacity of the autophagy modulators ATG14L, rubicon, UVRAG, and hVps34 to beclin 1 during auto- phagosome formation. These results suggest that the amyotrophic lateral sclerosis-linked Cu/Zn superoxide dismutase I G93A mutant can upregulate autophagic activity in NSC34 cells, but that this does not markedly affect beclin 1 complex components.     

Autophagic induction of amyotrophic lateral sclerosislinked Cu/Zn superoxide dismutase 1 G93A mutant in NSC34 cells

Previous studies have confirmed that the beclin 1 complex plays a key role in the initial stage of autophagy and deregulated autophagy might involve in amyotrophic lateral sclerosis.However,the mechanism underlying altered autophagy associated with the beclin 1 complex remains unclear.In this study,we transfected the Cu/Zn superoxide dismutase 1 G93A mutant protein into the motor neuron-like cell line NSC34 cultured in vitro.Western blotting and co-immunoprecipitation showed that the Cu/Zn superoxide dismutase 1 G93A mutant enhanced the turnover of autophagic marker microtubule-associated protein light chain 3II(LC3II)and stimulated the conversion of EGFP-LC3I to EGFP-LC3II,but had little influence on the binding capacity of the autophagy modulators ATG14L,rubicon,UVRAG,and hVps34 to beclin 1 during autophagosome formation.These results suggest that the amyotrophic lateral sclerosis-linked Cu/Zn superoxide dismutase 1 G93A mutant can upregulate autophagic activity in NSC34 cells,but that this does not markedly affect beclin 1 complex components.     

Deregulation of autophagy in postmortem brains of Machado‐Joseph disease patients

Autophagy, the major pathway for protein turnover, is critical to maintain cellular homeostasis and has been implicated in neurodegenerative diseases. The aim of this research was to analyze the expression of autophagy markers in postmortem brains from Machado‐Joseph disease (MJD) patients. The expression of autophagy markers in the cerebellum and the oculomotor nucleus from MJD patients and age‐matched controls with no signs of neuropathology was inspected postmortem by immunohistochemistry (IHC) and Western blot. Furthermore, autophagy was examined by means of transmission electron microscopy (TEM). Western blot and IHC revealed nuclear accumulation of misfolded ataxin‐3 (ATXN3) and the presence of ubiquitin‐ and p62‐positive aggregates in MJD patients as compared to controls. Moreover, the autophagic proteins, autophagy‐related gene (Atg) protein (ATG)‐7, ATG‐12, ATG16L2 and autophagosomal microtubule‐associated protein light chain 3 (LC3) were significantly increased in MJD brains relative to controls, while beclin‐1 levels were reduced in MJD patients. Increase in the levels of lysosomal‐associated membrane protein 2 (LAMP‐2) and of the endosomal markers (Rab7 and Rab1A) were observed in MJD patients relatively to controls. In addition, these findings were further confirmed by TEM in brain tissue where large vesicles accumulating electron‐dense materials were highly enriched in MJD patients. Postmortem brains with MJD exhibit increased markers of autophagy relative to age‐matched control brains, therefore suggesting strong dysregulation of autophagy that may have an important role in the course of MJD pathogenesis.     

Nuclear factor-kappaB-dependent cyclin D1 induction and DNA replication associated with N-methyl-D-aspartate receptor-mediated apoptosis in rat striatum

Cell cycle reentry has been found during apoptosis of postmitotic neurons under certain pathological conditions. To evaluate whether nuclear factor-kappaB (NF-kappaB) activation promotes cell cycle entry and neuronal apoptosis, we studied the relation among NF-kappaB-mediated cyclin induction, bromodeoxyuridine (BrdU) incorporation, and apoptosis initiation in rat striatal neurons following excitotoxic insult. Intrastriatally injected N-methyl-D-aspartate receptor agonist quinolinic acid (QA, 60 nmol) elicited a rise in cyclin D1 mRNA and protein levels (P<0.05). QA-induced NF-kappaB activation occurred in striatal neurons and nonneuronal cells and partially colocalized with elevated cyclin D1 immunoreactivity and TUNEL-positive nuclei. QA triggered DNA replication as evidenced by BrdU incorporation; some striatal BrdU-positive cells were identified as neurons by colocalization with NeuN. Blockade of NF-kappaB nuclear translocation with the recombinant peptide NF-kappaB SN50 attenuated the QA-induced elevation in cyclin D1 and BrdU incorporation. QA-induced internucleosomal DNA fragmentation was blunted by G(1)/S-phase cell cycle inhibitors. These findings suggest that NF-kappaB activation stimulates cyclin D1 expression and triggers DNA replication in striatal neurons. Excitotoxin-induced neuronal apoptosis may thus result from, at least partially, a failed cell cycle attempt.     

A combination of four active compounds alleviates cerebral ischemia–reperfusion injury in correlation with inhibition of autophagy and modulation of AMPK/mTOR and JNK pathways

SMXZF is a combination of Rb1, Rg1, schizandrin, and DT‐13 (6:9:5:4) derived from Sheng‐mai San, a widely used Chinese traditional medicine for the treatment of cardiovascular and cerebral diseases. The present study explores the inhibitory effects and signaling pathways of SMXZF on autophagy induced by cerebral ischemia–reperfusion injury. Male C57BL/6 mice were subjected to ischemia–reperfusion insult by right middle cerebral artery occlusion (MCAO) for 1 hr with subsequent 24 hr reperfusion. Three doses of SMXZF (4.5, 9, and 18 mg/kg) were administered intraperitoneally (i.p.) after ischemia for 1 hr. An autophagic inhibitor, 3‐methyladenine (3‐MA; 300 μg/kg), was administered i.p. 20 min before ischemia as a positive drug. We found that SMXZF significantly increased cerebral blood flow and reduced the infarct volume, brain water content, and the neurological deficits in a dose‐dependent manner. Similar to the positive control, SMXZF at 18 mg/kg also significantly inhibited autophagosome formation. Immunofluorescence staining and Western blotting demonstrated that SMXZF could significantly decrease the expression levels of beclin1 and microtubule‐associated protein 1 light chain 3. SMXZF also remarkably inhibited the phosphorylation of adenosine monophosphate‐activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) as well as the expression of c‐Jun N‐terminal kinase (JNK) and its phosphorylation induced by 24 hr reperfusion. Finally, we demonstrated that the optimal administration time of SMXZF was at the early period of reperfusion. This study reveals that SMXZF displays neuroprotective effect against focal ischemia–reperfusion injury, possibly associated with autophagy inactivation through AMPK/mTOR and JNK pathways. © 2014 Wiley Periodicals, Inc.     

Excitotoxic and metabolic damage to the rodent striatum: role of the P75 neurotrophin receptor and glial progenitors

After injury, the striatum displays several morphologic responses that may play a role in both regenerative and degenerative events. One such response is the de novo expression of the low-affinity p75 neurotrophin receptor (p75(NTR)), a gene that plays critical roles in central nervous system (CNS) cell death pathways. The present series of experiments sought to elucidate the cellular origins of this p75(NTR) response, to define the conditions under which p75(NTR) is expressed after striatal injury, and how this receptor expression is associated with neuronal plasticity. After chemical lesions, by using either the excitotoxin quinolinic acid (QA) or the complex II mitochondria inhibitor 3-nitropropionic acid (3-NP), we compared the expression of the p75(NTR) receptor within the rat striatum at different survival times. Intrastriatal administration of QA between 7 days and 21 days postlesion induced p75(NTR) expression in astrocytes that was preferentially distributed throughout the lesion core. P75(NTR) immunoreactivity within astrocytes was seen at high (100-220 nmol) but not low (50 nmol) QA doses. Seven and 21 days after 3-NP lesions, p75(NTR) expression was present in astrocytes at all doses tested (100-1,000 nmol). However, in contrast to QA, these cells were located primarily around the periphery of the lesion and not within the lesion core. At the light microscopic level p75(NTR) immunoreactive elements resembled vasculature: but did not colocalize with the pan endothelium cell marker RecA-1. In contrast, p75(NTR)-containing astrocytes colocalized with nestin, vimentin, and 5-bromo-2-deoxyuridine, indicating that these cells are newly born astrocytes. Additionally, striatal cholinergic neurons were distributed around the lesion core expressed p75(NTR) 3-5 days after lesion in both QA and 3-NP lesions. These cells did not coexpress the pro-apoptotic degradation enzyme caspase-3. Taken together, these data indicate that striatal lesions created by means of excitotoxic or metabolic mechanisms trigger the expression of p75(NTR) in structures related to progenitor cells. The expression of the p75(NTR) receptor after these chemical lesions support the concept that this receptor plays a role in the initiation of endogenous cellular events associated with CNS injury.     

Nuclear factor‐κB/p65 responds to changes in the Notch signaling pathway in murine BV‐2 cells and in amoeboid microglia in postnatal rats treated with the γ‐secretase complex blocker DAPT

Microglial cells constitutively express Notch‐1 and nuclear factor‐κB/p65 (NF‐κB/p65), and both pathways modulate production of inflammatory mediators. This study sought to determine whether a functional relationship exists between them and, if so, to investigate whether they synergistically regulate common microglial cell functions. By immunofluorescence labeling, real‐time polymerase chain reaction (RT‐PCR), flow cytometry, and Western blot, BV‐2 cells exhibited Notch‐1 and NF‐κB/p65 expression, which was significantly up‐regulated in cells challenged with lipopolysaccharide (LPS). This was coupled with an increase in expression of Hes‐1, tumor necrosis factor‐α (TNF‐α), and interleukin‐1β (IL‐1β). In BV‐2 cells pretreated with N‐[N‐(3,5‐difluorophenacetyl)‐1‐alany1]‐S‐phenyglycine t‐butyl ester (DAPT), a γ‐secretase inhibitor, followed by LPS stimulation, Notch‐1 expression level was enhanced but that of all other markers was suppressed. Additionally, Hes‐1 expression and NF‐κB nuclear translocation decreased as shown by flow cytometry. Notch‐1's modulation of NF‐κB/p65 was also evidenced in amoeboid microglial cells (AMC) in vivo. In 5‐day‐old rats given intraperitoneal injections of LPS, Notch‐1, NF‐κB/p65, TNF‐α, and IL‐1β immunofluorescence in AMC was markedly enhanced. However, in rats given an intraperitoneal injection of DAPT prior to LPS, Notch‐1 labeling was augmented, but that of TNF‐α and IL‐1β was reduced. The results suggest that blocking of Notch‐1 activation with DAPT would reduce the level of its downstream end product Hes‐1 along with suppression of NF‐κB/p65 translocation, resulting in suppressed production of proinflammatory cytokines. It is concluded that Notch‐1 signaling can trans‐activate NF‐κB/p65 by amplifying NF‐κB/p65‐dependent proinflammatory functions in activated microglia. © 2010 Wiley‐Liss, Inc.     

Rolipram reduces excitotoxic neuronal damage

Proinflammatory cytokines are supposed to be involved in the pathophysiology of neuronal damage following excitotoxic lesions. We examined the effect of rolipram, a TNF-alpha-inhibitor, on excitotoxic neuronal damage. Quinolinic acid (240 nmol in 1 microl) was injected stereotactically into the striatum of male Wistar rats. Four groups of QA rats were treated i.p. with solvent, MK-801 (4 mg/kg) or rolipram (0.3 mg/kg) which was started either 6 or 24 h after QA injection and continued with daily applications for 14 days. QA injection induced neuronal damage which affected 93% of the striatal area. MK-801 reduced this damage to 12% of the striatal area. Treatment with rolipram when started at 6 h after QA injection resulted in neuronal damage amounting to 60%; the result after starting at 24 h was not different from solvent (91%). The present results demonstrate that rolipram reduces neuronal damage induced by intrastriatal QA application.     

Effects of dopamine on LC3-II activation as a marker of autophagy in a neuroblastoma cell model

Dopamine at 100–500 μM has toxic effects on human SH-SY5Y neuroblastoma cells, manifested as apoptotic cell loss and strong autophagy. The molecular mechanisms and types of dopamine-induced cell death are not yet well known. Their identification is important in the study of neurodegenerative diseases that specifically involve dopaminergic neurons. We looked for changes in expression and content of proteins involved in apoptosis and autophagy after dopamine treatment. All the changes found were prevented by avoiding dopamine oxidation with N-acetylcysteine, indicating a key role for the products of dopamine oxidation in dopamine toxicity. As early as 1–2 h after treatment we found an increase in hypoxia-inducible factor-1α (HIF-1α) and an accumulation of ubiquitinated proteins. Proteins regulated by HIF-1α and involved in apoptosis and/or autophagy, such as p53, Puma and Bnip3, were subsequently increased. However, apoptotic parameters (caspase-3, caspase-7, PARP) were only activated after 12 h of 500 μM dopamine treatment. Autophagy, monitored by the LC3-II increase after LC3-I linkage to autophagic vacuoles, was evident after 6 h of treatment with both 100 and 500 μM dopamine. The mTOR pathway was inhibited by dopamine, probably due to the intracellular redox changes and energy depletion leading to AMPK activation. However, this mechanism is not sufficient to explain the high LC3-II activation caused by dopamine: the LC3-II increase was not reversed by IGF-1, which prevented this effect when caused by the mTOR inhibitor rapamycin. Our results suggest that the aggregation of ubiquitinated non-degraded proteins may be the main cause of LC3-II activation and autophagy. As we have reported previously, cytosolic dopamine may cause damage by autophagy in neuroblastoma cells (and presumably in dopaminergic neurons), which develops to apoptosis and leads to cell degeneration.     

Excessive Autophagy Contributes to Neuron Death in Cerebral Ischemia

Aims: To determine the extent to which autophagy contributes to neuronal death in cerebral hypoxia and ischemia. Methods: We performed immunocytochemistry, western blot, cell viability assay, and electron microscopy to analyze autophagy activities in vitro and in vivo. Results: In both primary cortical neurons and SH‐SY5Y cells exposed to oxygen and glucose deprivation (OGD)for 6 h and reperfusion (RP) for 24, 48, and 72 h, respectively, an increase of autophagy was observed as determined by the increased ratio of LC3‐II to LC3‐I and Beclin‐1 (BECN1) expression. Using Fluoro‐Jade C and monodansylcadaverine double‐staining, and electron microscopy we found the increment in autophagy after OGD/RP was accompanied by increased autophagic cell death, and this increased cell death was inhibited by the specific autophagy inhibitor, 3‐methyladenine. The presence of large autolysosomes and numerous autophagosomes in cortical neurons were confirmed by electron microscopy. Autophagy activities were increased dramatically in the ischemic brains 3–7 days postinjury from a rat model of neonatal cerebral hypoxia/ischemia as shown by increased punctate LC3 staining and BECN1 expression. Conclusion: Excessive activation of autophagy contributes to neuronal death in cerebral ischemia.     

Mitogen‐activated protein kinases support survival of activated microglia that mediate thrombin‐induced striatal injury in organotypic slice culture

Intracerebral hemorrhage‐associated tissue damage is triggered by blood‐derived serine proteases such as thrombin. In addition, our previous studies have suggested that mitogen‐activated protein (MAP) kinases contribute to intracerebral hemorrhage‐ and thrombin‐induced striatal tissue damage in vivo. Here we addressed the mechanisms of MAP kinase involvement in thrombin cytotoxicity in rat corticostriatal slice culture, focusing on striatal tissue damage. Thrombin induced apoptotic nuclear condensation and fragmentation in striatal cells, which was suppressed by DEVD‐CHO, a caspase‐3 inhibitor. DEVD‐CHO also prevented shrinkage of the striatal tissue induced by thrombin. Phagocytotic activity may be involved in tissue deterioration, because a phagocytosis inhibitor (cytochalasin D) and an inhibitor of phagocytosis of apoptotic cells (O‐phospho‐L ‐serine) suppressed shrinkage of the striatal tissue. OX42 immunostaining revealed that apoptosis‐like microglial cell death was induced only when thrombin treatment was combined with application of inhibitors of MAP kinase/extracellular signal‐regulated kinase kinase (PD98059), p38 MAP kinase (SB203580), or c‐Jun N‐terminal kinase (SP600125). Thrombin‐induced increase in the number of microglia was also prevented by these inhibitors of MAP kinase pathways. We also found that thrombin‐induced production of tumor necrosis factor (TNF)‐α was inhibited by PD98059, SB203580, and SP600125. Finally, thrombin‐induced neuronal apoptosis and shrinkage of the striatal tissue were significantly inhibited by anti‐TNF‐α neutralizing antibody. These results suggest that MAP kinases contribute to thrombin‐induced striatal damage by supporting survival of activated microglia, which induce neuron death by producing TNF‐α and cause tissue shrinkage by phagocytosing apoptotic cells. © 2010 Wiley‐Liss, Inc.     

Cypermethrin Activates Autophagosome Formation Albeit Inhibits Autophagy Owing to Poor Lysosome Quality: Relevance to Parkinson’s Disease

Parkinson’s disease (PD) is the second most familiar, progressive and movement-related neurodegenerative disorder after Alzheimer disease. This study aimed to decipher the role of autophagy in cypermethrin-induced Parkinsonism, an animal model of PD. Indicators of autophagy [expression of beclin 1, autophagy-related protein 12 (Atg 12), unc-51 like autophagy activating kinase 1 (Ulk 1), p62 and lysosome-associated membrane protein 2 (LAMP 2) and conversion of microtubule-associated protein 1A/1B-light chain 3 (LC3) I to II], signalling cascade [phosphorylated (p) 5′ adenosine monophosphate-activated protein kinase (p-AMPK), sirtuin 1 (Sirt 1), phosphorylated-mammalian target of rapamycin (p-mTOR), tuberous sclerosis complex 2 (TSC 2), p₃₁₇Ulk 1 and p₇₅₇Ulk 1 levels] and lysosome morphology were assessed in control and cypermethrin-treated rat model of PD. Autophagy markers were also measured in cypermethrin-treated neuroblastoma cells in the presence of 3-methyl adenine, a phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) class III inhibitor; vinblastine, an autophagosome elongation inhibitor; bafilomycin A1, an autophagolysosome and lysosome fusion/abnormal acidification inhibitor or torin 1, a mechanistic target of rapamycin inhibitor. Cypermethrin reduced LAMP 2 and increased p-AMPK and Sirt 1 without causing any change in other signalling proteins. 3-Methyl adenine did not change LC3 conversion; vinblastine and bafilomycin A1 decreased LAMP 2 expression in controls. While cypermethrin increased LC3 conversion in the presence of 3-methyl adenine, LAMP 2 reduction was more pronounced in vinblastine and bafilomycin A1-treated cells. Torin 1 normalized the expression of LAMP 2 without any change in other autophagy markers. Results demonstrate that albeit cypermethrin activates autophagosome formation, it reduces LAMP 2 expression and lysosome quality leading to autophagy inhibition.     

Inhibition of Autophagy via p53-Mediated Disruption of ULK1 in a SCA7 Polyglutamine Disease Model

Spinocerebellar ataxia type 7 (SCA7) is one of nine neurodegenerative disorders caused by expanded polyglutamine domains. These so-called polyglutamine (polyQ) diseases are all characterized by aggregation. Reducing the level of aggregating polyQ proteins via pharmacological activation of autophagy has been suggested as a therapeutic approach. However, recently, evidence implicating autophagic dysfunction in these disorders has also been reported. In this study, we show that the SCA7 polyglutamine protein ataxin-7 (ATXN7) reduces the autophagic activity via a previously unreported mechanism involving p53-mediated disruption of two key proteins involved in autophagy initiation. We show that in mutant ATXN7 cells, an increased p53–FIP200 interaction and co-aggregation of p53–FIP200 into ATXN7 aggregates result in decreased soluble FIP200 levels and subsequent destabilization of ULK1. Together, this leads to a decreased capacity for autophagy induction via the ULK1–FIP200–Atg13–Atg101 complex. We also show that treatment with a p53 inhibitor, or a blocker of ATXN7 aggregation, can restore the soluble levels of FIP200 and ULK1, as well as increase the autophagic activity and reduce ATXN7 toxicity. Understanding the mechanism behind polyQ-mediated inhibition of autophagy is of importance if therapeutic approaches based on autophagy stimulation should be developed for these disorders.     

Nuclear factor‐κB/Bcl‐XL pathway is involved in the protective effect of hydrogen‐rich saline on the brain following experimental subarachnoid hemorrhage in rabbits

Early brain injury (EBI), a significant contributor to poor outcome after subarachnoid hemorrhage (SAH), is intimately associated with neuronal apoptosis. Recently, the protective role of hydrogen (H₂) in the brain has been widely studied, but the underlying mechanism remains elusive. Numerous studies have shown nuclear factor‐κB (NF‐κB) as a crucial survival pathway in neurons. Here we investigated the role of H₂ in EBI following SAH, focusing on the NF‐κB pathway. A double blood injection model was used to produce experimental SAH, and H₂‐rich saline was injected intraperitoneally. NF‐κB activity within the occipital cortex was measured. Immunofluorescence was performed to demonstrate the activation of NF‐κB; Bcl‐xL and cleaved caspase‐3 were determined via Western blot. Gene expression of Bcl‐xL was detected by real‐time PCR, and TUNEL and Nissl staining were performed to illustrate brain injury in the occipital cortex. SAH induced a significant increase of cleaved caspase‐3. Correspondingly, TUNEL staining demonstrated obvious neuronal apoptosis following SAH. In contrast, H₂ treatment markedly increased NF‐κB activity and the expression of Bcl‐xL and decreased the level of cleaved caspase‐3. Additionally, H₂ treatment significantly reduced post‐SAH neuronal apoptosis. The current study shows that H₂ treatment alleviates EBI in the rabbits following SAH and that NF‐κB/Bcl‐xL pathway is involved in the protective role of H₂. © 2013 Wiley Periodicals, Inc.     

氟西汀对癫痫合并抑郁大鼠模型海马自噬的作用

目的 探讨氟西汀对癫痫合并抑郁大鼠海马齿状回自噬的影响。方法 将60只SD大鼠随机分为对照组、模型组、氟西汀组、3-甲基腺嘌呤（3-MA）组。采用体重、摄食量、旷场试验评定大鼠抑郁水平;采用免疫组化测定大鼠海马齿状回beclin1、LC3-I、mToR蛋白表达水平,荧光实时定量RT-PCR测定大鼠海马齿状回beclin1、LC3-I、mToR基因表达水平。结果 药物干预后,模型组体重、摄食量、垂直运动次数和水平运动次数明显低于对照组（P<0.01）;氟西汀组、3-MA组经药物治疗后以上指标高于模型组（P<0.01,P<0.05）。模型组海马齿状回beclin1、LC3-I表达显著升高,mToR表达下降,与对照组相比有统计学意义（P<0.01）;氟西汀组、3-MA组大鼠海马齿状回beclin1、LC3-I表达下降,mToR表达升高,与模型组相比差异有统计学意义（P<0.01）。结论 氟西汀可能通过改善癫痫合并抑郁大鼠海马齿状回区beclin1、LC3-I、mToR表达,抑制细胞自噬。