PROJECT SUMMARY/ ABSTRACT
Aging and chronic hyperglycemia results in several metabolic and biochemical perturbations including
elevation of a series of highly reactive a-dicarbonyl compounds (a-DCs, e.g., Methylglyoxal(MGO). a-DCs
are unavoidable byproducts largely of anaerobic glycolysis which react indiscriminately with proteins, lipids,
and DNA to yield a heterogeneous group of molecules called advanced glycation end products (AGEs). A
large body of evidence has linked accelerated glucose metabolism and diabetes to neurodegenerative
diseases like Alzheimer's disease (AD). We hypothesize that toxic byproducts of glucose metabolism that
result in the formation of AGEs explain the enhanced risk of AD due to hyperglycemia and diabetes. In support
of this AGEs in serum and AGE crosslinking in protein aggregates have been associated with enhanced
neurodegeneration in AD. However, AGEs are hard to model as they take years to accumulate in humans and
the mechanism by which they cause cellular damage remains to be elucidated. To overcome this gap, we have
established C. elegans (worm) models that significantly accumulate a-DCs and AGEs, exhibiting several age-
related pathologies, such as hypersensitivity to touch, neuronal damage, paralysis, and early mortality, all
within three weeks of adulthood. In addition, we have observed that direct administration of synthetic
methylglyoxal derived AGEs can directly cause neurotoxicity. Furthermore, we have observed that a C.
elegans model overexpressing the pro-aggregating form of tau, that has been implicated in Alzheimer's
disease, is sensitive to feeding either glucose or AGEs in the diet. In this proposal, we will test the hypothesis
that changes in glucose and lipid metabolism pathways, especially with age, influence MGO and associated
AGEs thereby causing neurodegeneration associated with AD. We will also determine the mechanisms by
which AGEs influence metabolic dysfunction and contribute to neurodegeneration in AD.
In Aim 1 we will explore a causal role for the effects of AGEs on neurodegeneration in normal aging and in
Alzheimer's disease models using synthetically derived AGEs. We will also examine the role of age-associated
changes in glucose metabolism in influencing the levels of MGO and AGEs and enhancing neurodegeneration
in models of AD. In Aim 2 we will determine the relationship between lipid metabolism and production of AGEs.
We will genetically and pharmacologically manipulate fatty acid oxidation pathways to examine their influence
on modulating neurodegeneration in normal aging and AD models through modulation of AGEs. In Aim 3 we
propose to identify the mechanisms by which AGEs mediate their toxicity leading to inhibition of fatty acid
oxidation and neurodegeneration. We will identify AGE-binding proteins and therapeutic targets to modulate
AGE-related neurodegeneration. These studies will identify several genetic and pharmacological targets to
ameliorate AGEs and slow down the progression of neurodegeneration in AD.