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Orlov, E.

Publications and source records attributed to Orlov, E..

2 recordsLinked to original sources
bioRxiv2021

Synaptosome microRNAs regulate synapse functions in Alzheimer's disease

MicroRNAs (miRNAs) are found in nerve terminals, synaptic vesicles, and synaptosomes, but it is unclear whether synaptic and cytosolic miRNA populations differ in Alzheimers disease (AD) or if synaptosomal miRNAs affect AD synapse activity. To address these questions, we generated synaptosomes and cytosolic fractions from postmortem brains of AD and unaffected control (UC) samples and analyzed them using a global Affymetrix miRNAs microarray platform. A group of miRNAs significantly differed (p<0.0001) with high fold changes variance (+/- >200-fold) in their expressions in different comparisons- 1) UC synaptosome vs UC cytosol, 2) AD synaptosomes vs AD cytosol, 3) AD cytosol vs UC cytosol, and 4) AD synaptosomes vs UC synaptosomes. MiRNAs data analysis revealed that some potential miRNAs were consistently different across sample groups. These differentially expressed miRNAs were further validated using AD postmortem brains, brains of APP transgenic (Tg2576), Tau transgenic (P301L), and wild type mice. The miR-501-3p, miR-502-3p and miR-877-5p were identified as potential synaptosomal miRNAs upregulated with disease progression based on AD Braak stages. Gene Ontology Enrichment and Ingenuity Pathway Analysis of synaptosomal miRNAs showed the involvement of miRNAs in nervous system development, cell junction organization, synapse assembly formation, and function of GABAergic synapse. This is the first description of synaptic versus cytosolic miRNAs in AD and their significance in synapse function.

neuroscience↗
bioRxiv2021

Novel microRNA-455-3p mouse models to study Alzheimers disease pathogenesis

MicroRNA-455-3p is one of the highly conserved miRNAs involved in several human diseases but newly explored by our lab in Alzheimers disease (AD). Our past studies unveiled the biomarker and therapeutic potentials of miR-455-3p in AD. Our in vitro study exhibited the protective role of miR-455-3p against AD toxicities in reducing full-length APP and amyloid-{beta} (A{beta}) protein levels, and also reducing defective mitochondrial biogenesis, impaired mitochondrial dynamics and synaptic deficiencies. Next, we sought to determine the essential roles of miR-455-3p in AD using mouse models. Therefore, for the first time we generated both transgenic (TG) and knockout (KO) mouse models of miR-455-3p. We determined the positive and negative effects of miR-455-3p on mice cognitive function, mitochondrial biogenesis, mitochondrial dynamics, mitochondrial number & length, dendritic spine density, synapse numbers and synaptic activity in 12-month-old miR-455-3p TG and KO mice. MiR-455-3p TG mice lived 5 months longer than wild-type (WT) mice, whereas KO mice lived 4 months shorter than their WT counter parts. Morris water maze test showed improved cognitive behavior, spatial learning and memory in miR-455-3p TG mice relative to age-matched WT mice and miR-455-3p KO mice. Further, mitochondrial biogenesis, dynamics and synaptic activities were enhanced in miR-455-3p TG mice, while these were reduced in KO mice. Overall, miR-455-3p TG mice displayed protective effects and miR-455-3p KO mice exhibited deleterious effects in relation to AD pathogenesis. Both mouse models could be ideal research tools to understand the molecular mechanism of miR-455-3p in AD and other human diseases.

neuroscience↗