Deficiency in docosahexaenoic acid (DHA), a brain-essential omega-3 fatty acid, is associated with cognitive decline. Here we report that, in cytokine-stressed human neural cells, DHA attenuates amyloid-beta (Abeta) secretion, an effect accompanied by the formation of NPD1, a novel, DHA-derived 10,17S-docosatriene. DHA and NPD1 were reduced in Alzheimer disease (AD) hippocampal cornu ammonis region 1, but not in the thalamus or occipital lobes from the same brains. The expression of key enzymes in NPD1 biosynthesis, cytosolic phospholipase A2 and 15-lipoxygenase, was altered in AD hippocampus. NPD1 repressed Abeta42-triggered activation of proinflammatory genes while upregulating the antiapoptotic genes encoding Bcl-2, Bcl-xl, and Bfl-1(A1). Soluble amyloid precursor protein-alpha stimulated NPD1 biosynthesis from DHA. These results indicate that NPD1 promotes brain cell survival via the induction of antiapoptotic and neuroprotective gene-expression programs that suppress Abeta42-induced neurotoxicity.
Human brains retain discrete populations of micro RNA (miRNA) species that support homeostatic brain gene expression functions; however, specific miRNA abundance is significantly altered in neurological disorders such as Alzheimer disease (AD) when compared with age-matched controls. Here we provide evidence in AD brains of a specific up-regulation of an NF-B-sensitive miRNA-146a highly complementary to the 3-untranslated region of complement factor H (CFH), an important repressor of the inflammatory response of the brain. Up-regulation of miRNA-146a coupled to down-regulation of CFH was observed in AD brain and in interleukin-1, A42, and/or oxidatively stressed human neural (HN) cells in primary culture. Transfection of HN cells using an NF-B-containing pre-miRNA-146a promoter-luciferase reporter construct in stressed HN cells showed significant up-regulation of luciferase activity that paralleled decreases in CFH gene expression. Treatment of stressed HN cells with the NF-B inhibitor pyrollidine dithiocarbamate or the resveratrol analog CAY10512 abrogated this response. Incubation of an antisense oligonucleotide to miRNA-146a (anti-miRNA-146a; AM-146a) was found to restore CFH expression levels. These data indicate that NF-Bsensitive miRNA-146a-mediated modulation of CFH gene expression may in part regulate an inflammatory response in AD brain and in stressed HN cell models of AD and illustrate the potential for anti-miRNAs as an effective therapeutic strategy against pathogenic inflammatory signaling.
Gene expression data from microarrays are being applied to predict preclinical and clinical endpoints, but the reliability of these predictions has not been established. In the MAQC-II project, 36 independent teams analyzed six microarray data sets to generate predictive models for classifying a sample with respect to one of 13 endpoints indicative of lung or liver toxicity in rodents, or of breast cancer, multiple myeloma or neuroblastoma in humans. In total, >30,000 models were built using many combinations of analytical methods. The teams generated predictive models without knowing the biological meaning of some of the endpoints and, to mimic clinical reality, tested the models on data that had not been used for training. We found that model performance depended largely on the endpoint and team proficiency and that different approaches generated models of similar performance. The conclusions and recommendations from MAQC-II should be useful for regulatory agencies, study committees and independent investigators that evaluate methods for global gene expression analysis.
The innate immune response and inflammatory signaling play determinant roles in brain homeostasis, neuroprotection, and repair; however, altered or excessive signaling in these injury defense systems contributes to the irreversible degeneration of brain cells, as typified in the common, age-related neurodegenerative disorder Alzheimer disease (AD). Abundant DNA array, Northern, RT-PCR, and Western gene expression analysis of AD brains have repeatedly shown a significant disruption in the homeostatic expression of essential brain genes and a progressive up-regulation of inflammatory gene expression, driven in part by overactivation of transcription factor NF-B. This supports both the development and progression of neurodegenerative disease processes (9 -16). Indeed the TLR/IL-1R-IRAK-NF-B signaling axis is substantially over-stimulated in AD brain (6, 9 -12). Components of this innate immunity and inflammatory pathway are known to play a central role in driving neuropathology, in part via overexpression of interleukin-1  (IL-1) and upregulating the generation of the 42-amino acid amyloid  42 (A42) peptide. These in turn induce transcription from the * This work was supported, in whole or in part, by National Institutes of Health Grant AG18031 (NIA; to W. J. L.
Micro RNA-146a (miRNA-146a) is an inducible, 22 nucleotide, small RNA over-expressed in Alzheimer’s disease (AD) brain. Up-regulated miRNA-146a targets several inflammation-related and membrane-associated messenger RNAs (mRNAs), including those encoding complement factor-H (CFH) and the interleukin-1 receptor associated kinase-1 (IRAK-1), resulting in significant decreases in their expression (p < 0.05, ANOVA). In this study we assayed miRNA-146a, CFH, IRAK-1 and tetraspanin-12 (TSPAN12), abundances in primary human neuronal-glial (HNG) co-cultures, in human astroglial (HAG) and microglial (HMG) cells stressed with Aβ42 peptide and tumor necrosis factor alpha (TNFα). The results indicate a consistent inverse relationship between miRNA-146a and CFH, IRAK-1 and TSPAN12 expression levels, and indicate that HNG, HAG and HMG cell types each respond differently to Aβ42-peptide + TNFα-triggered stress. While the strongest miRNA-146a-IRAK-1 response was found in HAG cells, the largest miRNA-146a-TSPAN12 response was found in HNG cells, and the most significant miRNA-146a-CFH changes were found in HMG cells, the ‘resident scavenging macrophages’ of the brain.
Background
Genome-wide association studies (GWAS) have established ADAMTS7 as a locus for coronary artery disease (CAD) in humans. Yet, these studies fail to provide directionality for the association between ADAMTS7 and CAD. Previous reports have implicated ADAMTS7 in the regulation of vascular smooth muscle cell (VSMC) migration, but a role and direction of impact for this gene in atherogenesis has not been shown in relevant model systems.
Methods and Results
We bred an Adamts7 whole body knockout (KO) mouse onto both the Ldlr and Apoe KO hyperlipidemic mouse models. Adamts7−/−/Ldlr−/− and Adamts7−/−/Apoe−/− mice displayed significant reductions in lesion formation in aortas and aortic roots as compared to controls. Adamts7 KO mice also showed reduced neointimal formation after femoral wire injury. Adamts7 expression was induced in response to injury and hyperlipidemia but was absent at later timepoints, and primary Adamts7 KO VSMCs showed reduced migration in the setting of TNFα stimulation. ADAMTS7 localized to cells positive for SMC markers in human CAD lesions, and sub-cellular localization studies in cultured VSMCs placed ADAMTS7 at the cytoplasm and cell membrane, where it co-localized with markers of podosomes.
Conclusions
These data represent the first in vivo experimental validation of the association of Adamts7 with atherogenesis, likely through modulation of vascular cell migration and matrix in atherosclerotic lesions. These results demonstrate that Adamts7 is proatherogenic, lending directionality to the original genetic association and supporting the concept that pharmacological inhibition of ADAMTS7 should be atheroprotective in humans, making it an attractive target for novel therapeutic interventions.
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