mRNA expression analysis of EWAS-related genes in AD CA1 pyramidal neurons AD CA1 astrocytes and AD CA1 microglia. Only two of the seven identified transcripts in the EWAS study were significantly differentially expressed, BIN1 in AD neurons and SERPINF2 in AD microglia. * indicates p < .05.
ANK1 gene expression change found in brain’s microglia cells associated with neuroinflammation. Researchers led by Arizona State University (ASU) and the Translational Genomics Research Institute (TGen) have identified altered expression of a gene called ANK1, which only recently has been associated with memory robbing Alzheimer’s disease, in specific cells in the brain. Using an extremely precise method of isolating cells called “laser capture microdissection,” researchers looked at 3 specific cell types – microglia, astrocytes and neurons – in the brain tissue of individuals with a pathological diagnosis of Alzheimer’s disease, and compared them to brain samples from healthy individuals and those with Parkinson’s disease.
Following sequencing of each of these cell types, the ASU-TGen led team found that altered ANK1 expression originates in microglia, a type of immune cell found in the brain and central nervous system. “Here, we provide evidence that microglia are the source of the previously observed differential expression patterns in the ANK1 gene in Alzheimer’s disease,” said Dr. Diego Mastroeni, an Assistant Research Professor at Biodesign’s ASU-Banner Neurodegenerative Disease Research Center, and the study’s lead author.
All 3 of the cell types in this study were derived from the hippocampus. In Alzheimer’s disease – and other forms of dementia – the hippocampus is one of the first regions of the brain to suffer damage, resulting in short-term memory loss and disorientation. Individuals with extensive damage to the hippocampus are unable to form and retain new memories.
“Using our unique data set, we show that in the hippocampus, ANK1 is significantly increased 4-fold in Alzheimer’s disease microglia, but not in neurons or astrocytes from the same individuals,” said Dr. Winnie Liang, an Assistant Professor, Director of TGen Scientific Operations and Director of TGen’s Collaborative Sequencing Center. “These findings emphasize that expression analysis of defined classes of cells is required to understand what genes and pathways are dysregulated in Alzheimer’s.”
Alzheimer’s features many signs of chronic inflammation, and microglia are key regulators of the inflammatory cascade, proposed as an early event in the development of Alzheimer’s, the study said. Because the study found that ANK1 also was increased 2X in Parkinson’s disease, “these data suggest that alterations in ANK1, at lease in microglia, may not be disease specific, but rather a response, or phenotype associated with neurodegeneration … more specifically, neuroinflammation.”
More than 5 million Americans have Alzheimer’s, an irreversible and progressive brain disorder that slowly destroys memory, thinking skills and eventually the ability to conduct even the simplest of tasks. For most patients, symptoms first appear in the mid-60s. For older Americans, it is the third leading cause of death, following heart disease and cancer, according to the National Institutes of Health. https://www.tgen.org/home/news/2017-media-releases/asu-tgen-find-source-of-alzheimers-gene.aspx.WWaE-YqQzUo
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0177814
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