The AICD (amyloid precursor protein [APP] intracellular domain) and C31, the caspase-cleaved C-terminal fragment of APP, have been found in the brains of patients with Alzheimer's disease (AD). Here, we demonstrate for the first time that the C-terminal fragments of APP (AICD [C57, C59] and C31) exert neurotoxicity on differentiated PC 12 cells and rat primary cortical neurons by inducing the expression of glycogen synthase kinase 3beta, forming a ternary complex with Fe65 and CP2/LSF/LBP1 in the nucleus, whereas deletion mutants and a point mutant with Y682G of the YENPTY domain, a Fe65 binding domain, do not. Moreover, expression of APP770 and Swedish mutant form of APP increased the levels of C-terminal fragments of APP (APP-CTs) in neuronal cells and also induced the up-regulation of glycogen synthase kinase-3beta at both the mRNA and the protein levels. In addition, we show that CP2/LSF/LBP1 binding site (nt +0 to approximately +10) in human glycogen synthase kinase 3beta promoter region is essential for the induction of the gene transcription by APP-CTs. The neurotoxicities induced by APP-CTs (AICD and C31) were accompanied by an increase in the active form of glycogen synthase kinase-3beta, and by the induction of tau phosphorylation and a reduction in nuclear beta-catenin levels, and led to apoptosis.

Minocycline is a semi-synthetic tetracycline antibiotic that effectively crosses the blood-brain barrier. Minocycline has been reported to have significant neuroprotective effects in models of cerebral ischemia, traumatic brain injury, amyotrophic lateral sclerosis, and Huntington's and Parkinson's diseases. In this study, we demonstrate that minocycline has neuroprotective effects in in vitro and in vivo Alzheimer's disease models. Minocycline was found to attenuate the increases in the phosphorylation of double-stranded RNAdependent serine/threonine protein kinase, eukaryotic translation initiation factor-2 a and caspase 12 activation induced by amyloid b peptide 1-42 treatment in NGF-differentiated PC 12 cells. In addition, increases in the phosphorylation of eukaryotic translation initiation factor-2 a were attenuated by administration of minocycline in Tg2576 mice, which harbor mutated human APP695 gene including the Swedish double mutation and amyloid b peptide 1-42 -infused rats. We found that minocycline administration attenuated deficits in learning and memory in amyloid b peptide 1-42 -infused rats. Increased phosphorylated state of eukaryotic translation initiation factor-2 a is observed in Alzheimer's disease patients' brains and may result in impairment of cognitive functions in Alzheimer's disease patients by decreasing the efficacy of de novo protein synthesis required for synaptic plasticity. On the basis of these results, minocycline may prove to be a good candidate as an effective therapeutic agent for Alzheimer's disease.

Alpha-synuclein (alpha-SN) is a ubiquitous protein that is especially abundant in the brain and has been postulated to play a central role in the pathogenesis of Parkinson's disease, Alzheimer's disease, and other neurodegenerative disorders. However, little is known about the neuronal functions of alpha-SN and the molecular and cellular mechanisms underlying neuronal loss. Here, we show that alpha-SN plays dual roles of neuroprotection and neurotoxicity depending on its concentration or level of expression. At nanomolar concentrations, a-SN protected neurons against serum deprivation, oxidative stress, and excitotoxicity through the PI3/Akt signaling pathway, and its protective effect was increased by Bcl-2 overexpression. Conversely, at both low micromolar and overexpressed levels in the cell, alpha-SN resulted in cytotoxicity. This might be related to decreased Bcl-xL expression and increased bax expression, which is subsequently followed by cytochrome c release and caspase activation and also by microglia-mediated inflammatory responses via the NFkappaB and mitogen-activated protein kinase pathways.

We have previously demonstrated that the active form of matrix metalloproteinase‐3 (actMMP‐3) is released from dopamine(DA)rgic neurons undergoing apoptosis. Herein, whether actMMP‐3 might be generated intracellularly, and if so, whether it is involved in apoptosis of DArgic neurons itself was investigated in primary cultured DArgic neurons of wild‐type, MMP‐3 knockout animals, and CATH.a cells. During apoptosis, gene expression of MMP‐3 is induced, specifically among the various classes of MMPs, generating the proform (55 kDa) which is subsequently cleaved to the catalytically active actMMP‐3 (48 kDa) involving a serine protease. Intracellular actMMP‐3 activity is directly linked to apoptotic signaling in DArgic cells: (i) Pharmacologic inhibition of enzymatic activity, repression of gene expression by siRNA, and gene deficiency all lead to protection; (ii) pharmacologic inhibition causes attenuation of DNA fragmentation and caspase 3 activation, the indices of apoptosis; and (iii) inhibition of the pro‐apoptotic enzyme c‐Jun N‐terminal protein kinase leads to repression of MMP‐3 induction. Under the cell stress condition, MMP‐3 is released as actMMP‐3 rather than the proform (proMMP‐3), and catalytically active MMP‐3 added to the medium does not cause cell death. Thus, actMMP‐3 seems to have a novel intracellular role in apoptotic DArgic cells and this finding provides an insight into the pathogenesis of Parkinson’s disease.

J. Neurochem. (2011) 116, 22–32. Abstract Matrix metalloproteinase‐3 (MMP‐3) is a member of the class of zinc‐dependent proteases known to degrade the extracellular matrix. MMP‐3 activity is regulated at three different levels: gene expression, proteolytic activation of the zymogen, and inhibition by the endogenous tissue inhibitors of metalloproteinase. A line of evidence indicates a role of MMP‐3 in neurodegeneration. In neuronal cells, MMP‐3 expression is increased in response to cell stress, and the cleaved, active MMP‐3 participates in apoptotic signaling. In the extracellular space, MMP‐3 triggers microglia to produce proinflammatory and cytotoxic molecules as well as MMP‐3, which in turn contribute to neuronal damage. MMP‐3 is increased in various experimental models of Parkinson’s disease that are produced by selective toxins and by inflammagen, and the neuronal death is attenuated by various ways that inhibit MMP‐3. α‐Synuclein, whose gene mutations are associated with familial forms of Parkinson’s disease, is proteolyzed by MMP‐3. Contribution of MMP‐3 toward the pathogenesis of Alzheimer’s disease and other neurodegenerative diseases has also been suggested. Thus, modulation of MMP‐3 expression and/or activity could be of therapeutic value for neurodegenerative diseases.

Quantification of nanoparticles in biological systems (i.e., cells, tissues and organs) is becoming a vital part of nanotoxicological and nanomedical fields. Dose is a key parameter when assessing behavior and any potential risk of nanomaterials. Various techniques for nanoparticle quantification in cells and tissues already exist but will need further development in order to make measurements reliable, reproducible and intercomparable between different techniques. Microscopy allows detection and location of nanoparticles in cells and has been used extensively in recent years to characterize nanoparticles and their pathways in living systems. Besides microscopical techniques (light microscopy and electron microscopy mainly), analytical techniques such as mass spectrometry, an established technique in trace element analysis, have been used in nanoparticle research. Other techniques require 'labeled' particles, fluorescently, radioactively or magnetically. However, these techniques lack spatial resolution and subcellular localization is not possible. To date, only electron microscopy offers the resolving power to determine accumulation of nanoparticles in cells due to its ability to image particles individually. So-called super-resolution light microscopy techniques are emerging to provide sufficient resolution on the light microscopy level to image or 'see' particles as individual particles. Nevertheless, all microscopy techniques require statistically sound sampling strategies in order to provide quantitative results. Stereology is a well-known sampling technique in various areas and, in combination with electron microscopy, proves highly successful with regard to quantification of nanoparticle uptake by cells.

Parkinson's disease (PD) is a progressive neurodegenerative disorder with a selective loss of dopaminergic neurons in the substantia nigra. Evidence suggests oxidation of dopamine (DA) to DA quinone and consequent oxidative stress as a major factor contributing to this vulnerability. We have previously observed that exposure to or induction of NAD(P)H:quinone reductase (QR1), the enzyme that catalyzes the reduction of quinone, effectively protects DA cells. Sulforaphane (SF) is a drug identified as a potent inducer of QR1 in various nonneuronal cells. In the present study, we show that SF protects against compounds known to induce DA quinone production (6-hydroxydopamine and tetrahydrobiopterin) in DAergic cell lines CATH.a and SK-N-BE(2)C as well as in mesencephalic DAergic neurons. SF leads to attenuation of the increase in protein-bound quinone in tetrahydrobiopterin-treated cells, but this does not occur in cells that have been depleted of DA, suggesting involvement of DA quinone. SF pretreatment prevents membrane damage, DNA fragmentation, and accumulation of reactive oxygen species. SF causes increases in mRNA levels and enzymatic activity of QR1 in a dose-dependent manner. Taken together, these results indicate that SF causes induction of QR1 gene expression, removal of intracellular DA quinone, and protection against toxicity in DAergic cells. Thus, this major isothiocyanate found in cruciferous vegetables may serve as a potential candidate for development of treatment and/or prevention of PD.Parkinson's disease (PD) is a progressive neurodegenerative disorder associated with a selective loss of the neurons containing dopamine (DA) in the substantia nigra pars compacta. Among the proposed underlying causes of DAergic neurodegeneration, oxidative stress is believed to play an important role. Lines of evidence suggest oxidation of DA and consequent quinone modification and oxidative stress as a major factor contributing to the vulnerability of DA cells (Hastings and Zigmond, 1997;Asanuma et al., 2003;Choi et al., 2003a). DA is easily oxidized spontaneously (Hastings and Zigmond, 1997) or enzymatically (Maker et al., 1981) to produce DA quinones. The DA quinone species are capable of covalently modifying cellular nucleophiles, including low molecular weight sulfhydryls and protein cysteinyl residues (Graham, 1978). In addition, when in excess, DA quinone cyclizes to become the highly reactive aminochrome, whose redox-cycling leads to generation of superoxide and depletion of cellular NADPH. The detrimental role of DA quinones suggests a requirement for effective mechanisms to remove the cellular quinones. NAD(P)H:quinone reductase (QR1) [DT-diaphorase; NAD(P):H-(quinone acceptor)oxidoreductase; EC 1.6.5.2] is an enzyme that catalyzes two-electron reduction of quinone to the redox-stable hydroquinone (Joseph et al., 2000;Cavelier and Amzel, 2001) and therefore might effectively protect DA cells from quinone-induced damages. A safe and effective inducer of QR1 would be a good candidate with which to p...

IntroductionAdolescent pregnancy causes serious problems not only for girls, but also for their family, and society. This study aimed to understand factors related to adolescent pregnancy in low- and middle-income countries using a multilevel approach adopted by Bronfenbrenner's ecological model.MethodsA total of 11,933 studies published in between 2000 and 2015 were identified in 4 databases. Based on inclusion criteria and risk of bias assessment, a total of 67 articles were retrieved for analysis.ResultsThematic analysis revealed that early marriage, sexual risk behaviors, substance use, family experience of adolescent birth, peer pressure, and lack of sex education and health service increased the hazards of adolescent pregnancy. Communication with parents, school activities, community meetings, laws, and government policies protected adolescents from pregnancy.ConclusionsResults of this study suggests that the background of adolescents and complex interactions among various factors should be considered for pregnancy. In future research, mixed-method that supplements the methodological weaknesses of previous studies is also recommended.