Title. Synaptosomal MicroRNAs, Synaptic Damage and Cognitive Decline in Alzheimer's Disease
Project summary/abstract
The purpose of our study is to determine the role of synaptosomal microRNAs (miRNAs) in Alzheimer's
disease (AD) progression and pathogenesis. Synapses are the most important compartments of neuron that
deliver signals to adjacent neuron and maintain healthy synaptic functions of the brain. Synapse territories are
composed of synaptic vesicles, synaptic proteins, mitochondria, neurotransmitters receptors, postsynaptic
density protein and localized small RNAs and miRNAs. Recently, several studies identified the miRNAs
enrichments at synapse, synaptic vesicles and synaptosomes. However, the role of synapse-associated
miRNAs in AD progression is completely unexplored. In the first part of our study, we will identify the
synaptosome-specific miRNAs that are deregulated in AD, and further, we will characterize their roles in AD
progression and pathogenesis. Synaptosomal fraction will be extracted from frontal cortex region of
postmortem brains from AD (n=15) and healthy controls (n=15). Total RNA will be extracted from
synaptosomal fraction and processed for miRNA and mRNA sequencing. The deregulated synaptosome-
specific miRNAs will be characterized in vitro using miRNA mimics and inhibitor(s) approaches and mutant
APP and p-tau cDNA constructs. Impact of synaptosomal miRNAs will be studied against Aß and p-tau
induced toxicities. In second part we will determine the role of synaptosomal miRNAs in Aß induced synaptic
and cognitive dysfunction in AD. The impact of synaptosomal miRNAs will be studied on healthy neurons and
AD neurons with Aß induced toxicities. We will focus on neuronal processing, neuronal growth and network
development and synaptic plasticity using APP primary neuronal cultures. Alteration of synaptosomal miRNAs
expression and synaptic proteins will be studied with disease progression in APP transgenic (TG) and APP
knockout (KO) mice. We will execute the synaptosome-specific miRNAs expression with various cognitive
behavioral and biochemical tests in 2-, 6-, 12- and 18-month-old APP TG and APP KO mice lines relative to
age-matched TG negative wild-type (WT) mice. And in third part we will study the role of synaptosomal
miRNAs in phosphorylated-tau (p-tau) induced synaptic and cognitive dysfunction in AD. The impact of
synaptosomal miRNAs will be studied on p-tau induced toxicity in neurons, healthy neurons processing,
neuronal growth and network development and synaptic plasticity using tau primary neuronal culture. Alteration
of synaptosomal miRNAs and synaptic proteins will be studied with disease progression in Tau TG and Tau
KO mice. We will execute the synaptosome-specific miRNAs expression with various cognitive behavioral and
biochemical tests in 2-, 6-, 12- and 18-month-old tau TG and KO mice relative to WT mice. Our study outcome
will provide the answers for - 1) presence of synaptosomal miRNAs at AD synapse, 2) synaptosome-
associated miRNAs linked with Aß and p-tau pathologies in AD, 3) Overall synapse function, synaptic activity,
assessment of therapeutic value of synaptosome-associated miRNAs in AD.