PROTEIN CARBONYLATION AND AXONAL DAMAGE IN EAE

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DESCRIPTION (provided by applicant): Our long-term goal is to define and characterize the mechanisms underlying tissue injury in multiple sclerosis, the most common demyelinating disease of the central nervous system in humans. In recent years, oxidative stress has been implicated in the pathophysiology of both multiple sclerosis and its animal model, experimental allergic encephalomyelitis (EAE). Reactive oxygen species (ROS) are released by activated macrophages/microglia or are endogenously generated by dysfunctional mitochondria in the nerve cells. Although there is unquestionable experimental evidence demonstrating that oxidative stress plays a causal role in these disorders, the precise mechanism(s) by which ROS produces tissue damage is far from clear. A major consequence of ROS accumulation is the non-enzymatic introduction of aldehydes or ketones into specific amino acid residues of proteins (i.e. carbonylation). Based on recent reports regarding the molecular and cellular consequences of protein carbonylation in other systems and a number of important findings from our laboratory, we hypothesize that a major outcome of oxidative stress in EAE is the carbonylation of neuronal proteins, which contributes to tissue damage and axonal injury. We also put forth the idea that inhibition of protein carbonylation will be therapeutic in this disease. To test our hypothesis, we will measure the levels of protein carbonyls in the spinal cord and brain of remitting/relapsing EAE mice in relationship to well-established pathological hallmarks of the disease (inflammation, neuronal death, axonal damage and demyelination). These studies will employ state-of the-art biochemical and immunocytochemical techniques. We will then identify the oxidized proteins in the inflammatory and degenerative stages of the disease by redox proteomics, and will ascertain both the chemical nature and origin of the oxidizing species from the type of carbonylated amino acid residues produced. Finally, we will examine the ability of various carbonyl scavengers and metabolic inhibitors to prevent tissue injury and axonal damage in EAE animals. If successful, these studies will uncover a novel molecular mechanism by which oxidative stress causes chronic disability in demyelinating disorders. PUBLIC HEALTH RELEVANCE: Multiple sclerosis (MS) is a neurological disorder that affects approximately 1 in 700 young adults in the US. We have recently observed that a special type of oxidative process called carbonylation modifies several brain proteins from MS patients. These modifications affect protein function and likely contribute to tissue injury in this devastating disease. Using a mouse model of MS, we will determine whether drugs that reduce protein carbonylation can effectively prevent tissue damage and neurological deficits. We envision that in the future these agents could be administered in combination with antioxidants, anti-inflammatory or neuroactive substances for an improved clinical management of chronic MS.