Diethylene glycol (DEG) has produced many mass poisonings that have led to severe acute kidney injury, peripheral neuropathy, and >800 deaths throughout the world. Although DEG is a health concern in the US because it is found in easily available consumer products, its toxicity offers a unique aspect in the relationship between its nephrotoxicity and its neurotoxicity. Because the toxic mechanism is not well understood, the proposed studies relating the mechanism of the renal damage and that of the peripheral neuropathy will advance the field by increasing the knowledge of such damage-associated pathways. Our studies have definitively shown that the metabolite responsible for the renal damage is diglycolic acid (DGA), however its role in the neuropathy is not established. Mechanistic studies with DGA have shown that it produces mitochondrial dysfunction as an inhibitor of oxidative phosphorylation leading to ATP depletion and ultimately cell death. DGA has also been shown to chelate free calcium in a similar strength as known calcium chelator EGTA. Part of the mechanism of DGA-induced cell death might include chelation of intracellular calcium, thereby decreasing transport of energy-producing substrates into the mitochondria by the calcium- regulated protein aralar, which then can explain the decreased production of ATP by the electron transport We hypothesize that DGA exerts a detrimental change in intracellular calcium homeostasis by chelating cytosolic calcium stores, thus leading to mitochondrial dysfunction in both the kidney and in sensorimotor neurons. Development of efficacious therapy to counteract DGA toxicity is needed for better treatment of DEG poisoning, so this research is critical to determine the mechanism by which DGA is toxic and to be able to develop and test potential new therapies.
Aim 1 will establish an animal model of the neurotoxicity of DEG and will characterize the toxicity profile of DGA in the brain and kidney as it pertains to calcium homeostasis and aralar-mediated mitochondrial dysfunction.
Aim 2 will examine the effects of DGA on calcium homeostasis in the renal proximal tubule (HPT) cell model and kinetically relate these changes to DGA-mediated mitochondrial dysfunction.
Aim 3 will relate alterations by DGA in calcium-related proteins to changes in calcium homeostasis and will examine changes in aralar levels in HPT cells to test whether such manipulations rescue effects of DGA toxicity. Outcome. These mechanistic studies will significantly impact the field of kidney and neuronal function by using a unique toxicological model (DGA accumulation) to assess common mechanisms of toxicity between the two tissues. These in vivo and in vitro studies will convincingly show that DGA produces organ damage by altering calcium- regulated uptake of energy substrates thereby leading to inhibition of mitochondrial function. AREA Impact. This project will offer area undergraduates an excellent research training experience and thus will enhance the research capacity of the NW Louisiana region.
Diethylene glycol (DEG), a widely-used chemical that is often found in consumer products in the US, has produced many, highly-fatal poisoning epidemics throughout the world in which it has produced a failure of the kidney and damage to peripheral nerves leading to paralysis. We have recently shown that a breakdown product known as diglycolate, rather than DEG itself, is responsible for the renal injury and that it does this by damaging mitochondria. However, there is hardly anything known about how DEG produces the nervous system damage, so these studies will develop an animal model for the nervous system damage and will investigate whether diglycolate produces the kidney and neurological damage by chelating calcium which then leads to the loss of mitochondrial function. These studies should contribute important knowledge that can relate mechanisms by which toxic substances can affect both the kidney and nervous system.
