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Reddy, P. H.

Publications and source records attributed to Reddy, P. H..

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

A partial reduction of Drp1 enhances mitophagy, autophagy, mitochondrial biogenesis, dendritic spines and synaptic activity in a transgenic Tau mouse model of Alzheimer disease

The purpose of our study is to understand the impact of a partial dynamin-related protein 1 (Drp1) on cognitive behavior, mitophagy/autophagy, mitochondrial and synaptic activities in transgenic Tau mice in Alzheimers disease (AD). Our lab reported increased levels of A{beta} and P-Tau, and abnormal interactions between A{beta} and Drp1, P-Tau and Drp1 induced increased mitochondrial fragmentation and reduced fusion and synaptic activities in AD. These abnormal interactions, result in the proliferation of dysfunctional mitochondria in AD neurons. Recent research on mitochondria revealed that fission protein Drp1 is largely implicated in mitochondrial dynamics in AD. To determine the impact of reduced Drp1 in AD, we recently crossed transgenic Tau mice with Drp1 heterozygote knockout (Drp1+/-) mice and generated double mutant (Drp1+/- X Tau) mice. In the current study, we assessed cognitive behavior, mRNA and protein levels of mitophagy, autophagy, mitochondrial biogenesis, dynamics and synaptic genes, mitochondrial morphology & mitochondrial function, dendritic spines in Tau mice relative to double mutant mice. When compared to Tau mice, double mutant mice did better on Morris Maze (reduced latency to find hidden platform, increased swimming speed and time spent on quadrant) and rotarod (stayed a longer period of time) tests. Both mRNA and proteins levels autophagy, mitophagy, mitochondrial biogenesis and synaptic proteins were increased in double mutant mice compared to Tau mice. Dendritic spines were significantly increased; mitochondrial number is reduced and length is increased in double mutant mice. Based on these observations, we conclude that reduced Drp1 is beneficial in a symptomatic-transgenic Tau mice.

neuroscience↗