Calcium dysregulation and vulnerability of entorhinal cortex neurons in Alzheimer's disease

ABSTRACT The broad, long-term objective of this multi-PI grant application is to understand the role of calcium (Ca2+) dysregulation as the mechanistic driver for synaptic loss between the lateral entorhinal cortex (LEC) and hippocampus (HPC) in evolving Alzheimer’s disease (AD). While dysfunction of the LEC-HPC circuit has been implicated, the cause of the early, selective vulnerability of LEC neurons and projections remain unknown. We will test the hypothesis that dysregulation of neuronal Ca2+ signaling plays a key role in LEC-HPC circuit dysfunction in early AD. Specifically, in experiments with the APPKI mouse model of AD, we will investigate if normalization of the activity of two key proteins, the Ca2+-dependent phosphatase calcineurin (CaN) or the prolyl isomerase, Pin1 rescues defects in LEC–HPC communication, function and stability in early AD. Pin1 is a key target of CaN-mediated inhibition in neurons, directly leading to synaptic and neuronal loss. In experiments with APPKI mice, we will also determine if dominant negative Pin1 accelerates defects in LEC–HPC communication irrespective of CaN normalization in APPKI mice. We will use a combination of molecular, biochemical, imaging, electrophysiological, behavioral and neuropathological techniques to address these specific aims. The proposed studies, if successful, will provide a mechanistic understanding of early AD evolution as well as a rationale for the use of CaN inhibitors such as FK506 or voclosporin to treat early AD.