Aging results in the accumulation of a series of highly reactive and toxic biochemical, called ?-dicarbonyl compounds (?-DCs, e.g., methylglyoxal/MGO). These ?-DCs react indiscriminately with protein and DNA to cause irreversible damage to these macromolecules by forming a class of compounds called advanced glycation end products (AGEs). AGEs are associated with aging and several age-related pathologies, but they are hard to model, as they take years to accumulate, and the evidence for their causal role is limited. Prior studies reveal that cellular detoxification of MGO, that forms AGEs, is primarily carried out by the evolutionarily conserved glyoxalase enzymes (GLO1 and DJ1). Utilizing mutants for these enzymes, we have established a Caenorhabditis elegans (worm) model, to study ?-DC and AGEs-related pathologies. These animals significantly accumulate ?-DCs and AGEs, exhibiting several age-related pathologies, such as hypersensitivity to touch, neuronal damage, obesity, paralysis, and early mortality, all within three weeks of adulthood which would take decades in humans to manifest. Our studies with this model demonstrate that a conserved Transient Potential Receptor (TRP) channel, TRPA-1, acts as a conserved sensor for AGE-stress to activate Skn-1/Nrf2 and regulate both glutathione-dependent (GLO1) and -independent (DJ1) glyoxalases enzyme to reduce AGE-stress ultimately. Interestingly, tissue-specific experiments with SKN-1 and DJ1s suggest that MGO levels in the intestine influence degeneration of neurons. In this proposal, we will test the hypothesis that cell non-autonomous action of AGEs contributes to aging and age-related disease pathologies.
In Aim 1 we will explore a causal role for the effects of AGEs on pathological phenotypes using synthetically derived AGEs. Labelled derivatives will be used to identify the transport and targets of AGEs. We describe for the first time that administering synthetic AGEs elicits significant biological activity, leading to obesity, neurodegeneration and reduced lifespan in C. elegans. Given that AGEs are found in the circulation in mammals and are also obtained from the diet, it argues for their potential role as non-autonomous factors in aging.
In Aim 2 we will explore both the synthesis and detoxification of MGO stress, a precursor to the formation of AGEs. We will also test the hypothesis that cell non-autonomous effects of glyoxalases in intestine enhances AGE production and leads to neurodegeneration. Furthermore, we will examine the hypothesis that inhibition of fat metabolism enhances AGEs and ultimately neurodegeneration by altering synthesis of MGO.
In Aim 3 we will characterize the AGE-binding proteins from both worms and mammalian neurons for their effects on lifespan and neurodegeneration. Together these studies will identify several conserved genes and pathways that modulate neuronal damage due to AGEs and provide novel therapeutic targets to ameliorate the effects of AGEs on lifespan and healthspan.
Advanced Glycation End-products (AGEs) are known to accumulate with age enhancing the risk of diabetic pathologies and several neurodegenerative diseases including Alzheimer's (AD) and Parkinson's disease (PD). We will use Caenorhabditis elegans and mammalian cell culture to dissect the conserved pathways that influence the production of AGEs and identify protein targets of AGEs that mediate its downstream pathological effects in a non-autonomous manner. Through this proposal, we will uncover how AGEs play a pervasive and conserved role in aging and age-related diseases using invertebrate and cell culture models.