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ABSTRACT: Overproduction and accumulation of amyloid-β (Aβ) have been proposed to be an initiating factor of neuron loss in Alzheimer's disease (AD). AKT is a pivotal molecule in regulating neuronal survival, however, it is still not known whether upregulation of AKT can protect the cells from the Aβ-induced apoptosis. By using cell viability assay and flow cytometry, we demonstrated in the present study that overexpression of AKT could significantly attenuate the cell apoptosis induced by Aβ1-42, whereas simultaneous inhibition of PI3 K, the immediate upstream stimulator of AKT, abolished the protective effect of AKT in HEK293 cells. Upregulation of AKT restored the Aβ-induced alterations of the mitochondria-related Bcl-2 family members (including Bcl-xL, Bcl-w, Bad, and Bax) and suppressed the activation of caspase-3 and JNK. Our data suggest that upregulation of AKT could be a promising therapeutic strategy for arresting Aβ toxicity in AD patients.
Journal of Alzheimer's disease: JAD 03/2011; 25(2):337-45. · 3.74 Impact Factor
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ABSTRACT: To study the role of autophagy in the death of dopaminergic neurons induced by 6-hydroxydopamine (6-OHDA).
Rat models of Parkinson disease (PD) were established by stereotaxic administration of 6-OHDA (8 μg) into the unilateral substantia nigra par compact (SNpc). Autophagosomes in the SNpc were observed with transmission electron microscopy (TEM), and the expression of autophagy-related protein LC3 was determined with immunofluoresence (IF) assay.
Under TEM, the autophagosomes were found in the ipsilateral SNpc 6-24 h after 6-OHDA injection, which suggested the activation of autophagy. IF assay showed significantly increased LC3 expression in 6-OHDA-damaged TH-positive neurons as compared to the control group.
The increase of autophagosomes and activation of autophagy may play a role in dopaminergic neuron death induced by 6-OHDA.
Nan fang yi ke da xue xue bao = Journal of Southern Medical University 12/2010; 30(12):2649-51.
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ABSTRACT: The finding of nuclear translocation of cathepsin L and its ability to process the CDP/Cux transcription factor uncovers an important role of cathepsin L in control of cell cycle progression. As the expression of certain cell cycle regulators is associated with nigral neuronal death, the present study was sought to investigate if nuclear translocation of cathepsin L and expression of certain cyclins were induced in DA neurons by 6-hydroxydopamine (6-OHDA). The neuroprotective effects of the cell cycle inhibitor olomoucine against 6-OHDA-induced death of nigral neurons were examined. Using immunocytochemistry and real-time PCR we demonstrated that cyclin D1, cyclin B1 and proliferating cell nuclear antigen (PCNA) were aberrantly expressed in some dopaminergic neurons after 6-OHDA infusion. The nuclear translocation of cathepsin L and up-regulation of LC3, a protein involved in autophagy, were observed in nigral DA neurons. Olomoucine, a cyclin dependent kinase (CDK) inhibitor, reduced contralateral rotations and the loss of TH-positive neurons in substantia nigra induced by lesion with 6-OHDA. Pretreatment of rats or primary DA neurons with olomoucine resulted in a partial blockade of nuclear translocation of cathepsin L. Olomoucine also increased the expression of punctate LC3 immunoreactivity, indicating activation of autophagy. These findings suggest that olomoucine may exert neuroprotective effects through inhibiting cathepsin L nuclear translocation and activating autophagy.
Brain research 03/2009; 1264:85-97. · 2.46 Impact Factor
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ABSTRACT: To investigate the effects of bilobalide on the activation of NF-kappaB, and apoptosis of dopaminergic neurons induced by 6-hydroxydopamine (6-OHDA).
A rat model of Parkinson's disease was produced with a unilateral infusion of 6-OHDA (8 mug) into the substantia nigra par compact. Bilobalide was administered 5, 10, and 20 mg/kg (ip) once a day for 7 d, starting 6 d prior to the 6- OHDA infusion. The rats were subjected to locomotor activity and rotational behavior testing 2 or 3 weeks after the 6-OHDA infusion. The expressions of tyrosine hydroxylase (TH) and NF-kappaB p65 were examined by immunofluorescence. The loss of dopaminergic neurons was detected by Nissl's staining. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling was used to identify apoptosis.
The behavioral changes due to 6-OHDA were significantly restored by bilobalide pretreatment. Bilobalide inhibited the 6-OHDA-induced loss of TH-positive neurons, decreased the activation of NF-kappaB, and protected dopaminergic neurons from apoptosis remarkably.
NF-kappaB activation contributes to the 6-OHDA-induced loss of dopaminergic neurons, and the inhibition of the NF-kappaB pathway is likely to be involved in the neuroprotective effect of bilobalide.
Acta Pharmacologica Sinica 06/2008; 29(5):539-47. · 1.95 Impact Factor
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ABSTRACT: Aim: To investigate the effects of bilobalide on the activation of NF-κB, and apoptosis of dopaminergic neurons induced by 6-hydroxydopamine (6-OHDA). Methods: A rat model of Parkinson's disease was produced with a unilateral infusion of 6-OHDA (8 μg) into the substantia nigra par compact. Bilobalide was administered 5, 10, and 20 mg/kg (ip) once a day for 7 d, starting 6 d prior to the 6-OHDA infusion. The rats were subjected to locomotor activity and rotational behavior testing 2 or 3 weeks after the 6-OHDA infusion. The expressions of tyrosine hydroxylase (TH) and NF-κB p65 were examined by immunofluorescence. The loss of dopaminergic neurons was detected by Nissl's staining. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling was used to identify apoptosis. Results: The behavioral changes due to 6-OHDA were significantly restored by bilobalide pretreatment. Bilobalide inhibited the 6-OHDA-induced loss of TH-positive neurons, decreased the activation of NF-κB, and protected dopaminergic neurons from apoptosis remarkably. Conclusion: NF-κB activation contributes to the 6-OHDA-induced loss of dopaminergic neurons, and the inhibition of the NF-κB pathway is likely to be involved in the neuroprotective effect of bilobalide.
Acta Pharmacologica Sinica 04/2008; 29(5):539 - 547. · 1.95 Impact Factor
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ABSTRACT: 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.
Journal of Neuroscience Research 06/2007; 85(6):1295-309. · 2.74 Impact Factor
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ABSTRACT: To investigate the relationship between methylenetetrahydrofolate reductases (MTHFR) polymorphisms and colorectal cancer susceptibility.
A case-control study of 126 patients and 343 healthy controls was conducted to investigate the roles of MTHFR C677T and A1298C polymorphisms in colorectal cancer development. Genotypes of C677T and A1298C polymorphisms were analyzed by polymerase chain resction-restriction fragment length polymorphism (PCR-RFLP) methods.
The frequencies of MTHFR 677T and 1298C allele were 39.7% and 17.1%, respectively. After adjustment for age and sex, the MTHFR 1298C alleles seemed to have reduced association on the risk of colorectal cancer comparing to wild types. Among those with 677T and 1298A alleles, a decreased risk of colorectal cancer was observed: a 4-fold decrease in colorectal cancer risk (OR = 0.552, 95% CI: 0.265 - 1.150) in those with 677T and 1298C alleles. Men who were ex-drinkers and with MTHFR 1298C allele had a 2-fold increase in risk of colorectal cancer (OR = 3.307, 95% CI: 0.521 - 17.698) while no increased risk was seen among those current-drinkers.
This study suggested that certain MTHFR C677T and A1298C might be associated with the risk of colorectal cancer development. The interaction between MTHFR 1298AC polymorphisms and ex-drinking might also serve as a risk factor of colorectal cancer.
Zhonghua liu xing bing xue za zhi = Zhonghua liuxingbingxue zazhi 08/2004; 25(7):612-6.
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ABSTRACT: The Bcl10 gene has recently been cloned from the chromosomal translocation t(1:14) (p22; q32) in a low-grade mucosa-associated lymphoid tissue (MALT) lymphoma, and was implicated in the pathogenesis of this and several other tumor types. In yeast two hybrid systems, when it was fused to Gal4 DNA-binding domain of pGBT9, this fusion protein can activate the expression of reporter genes without Gal4-AD domain. Through deletion assay and secondary structure prediction, we found that the N-terminal of Bcl10 contributed more to activation than the C-terminal. It has been recently reported that Bcl10 expression is correlated with the activation of NF-kappaB in eukaryotic cells, so it may represent an important role in protein expression. Our research is the first to demonstrate a new function of Bcl10: transcription activation in yeast.
Molecular and Cellular Biochemistry 05/2003; 246(1-2):97-103. · 2.06 Impact Factor
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ABSTRACT: A sensitive and quantitative in vitro analysis method was established to detect the nascent RNAs stimulated by angiogenin using the nuclei isolated from human umbilical vein endothelial cells (HUVE). Angiogenin was mixed with nuclei in the reaction buffer, then transcription was initiated by adding the NTPs mixture. The RNA products were measured quantitatively by [alpha-(32)P]CTP incorporation with a liquid scintillation counter, either after removing free isotope by using spin column, or cutting the electrophoresis lane and counting after autoradiography. It was found that the optimum reacting temperature was 30 degrees, the most suitable reaction time was 30 min for this system, and the transcription enhancement activity of angiogenin was dose-dependent with the feasible concentration being 1 mg/L. Higher concentration of angiogenin degraded the RNA products in the system, suggesting that there is a mechanism to control the entry and accumulation of angiogenin in the target cells, which ensured angiogenin to play its role properly in the cells. Based on the evidence that angiogenin bound to DNA in nucleolus and enhanced RNA transcription, it was proposed that angiogenin might act as a trans-acting factor in nucleus to regulate RNA transcription, and inhibition of angiogenin-stimulated RNA transcription might be a promising target for screening anti-angiogenesis inhibitor.
Sheng wu hua xue yu sheng wu wu li xue bao Acta biochimica et biophysica Sinica 05/2003; 35(4):350-4.
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ABSTRACT: Three current strains of measles virus (MV) Fu, IMA and SMD, isolated using B95a cell line, were adapted to Vero cells. After adaption, these strains obtained the ability to agglutinate African green monkey red blood cells (AGM-RBC). We compared hemagglutinin gene sequences and fusion gene sequences of these two kinds of viruses. Fu strain has an Asn (HAD negative) to Tyr (HAD positive) substitution at position 481 in the hemagglutinin glycoprotein. IMA strain has an Asp(HAD negative) to Asn(HAD positive) substitution at position 14 and a Ser(HAD negative) to Gly (HAD positive) substitution at position 546 in the protein. F gene was confirmed identical between viruses. Our data show that two mutations, Asn to Tyr at position 481 and Ser to Gly at position 546 in hemagglutinin glycoprotein are responsible for alteration in hemadsorption.
Sheng wu hua xue yu sheng wu wu li xue bao Acta biochimica et biophysica Sinica 02/1998; 30(5):488-494.
