CONTRIBUTION OF THE ALDA-1 ACTIVATOR OF THE ENZYME ALDEHYDE DEHYDROGENASE 2 IN THE PROGRESSION OF AMYOTROPHIC LATERAL SCLEROSIS IN SOD1*G93A MICE.

Abstract

Recently, knowledge about the pathophysiology of amyotrophic lateral sclerosis (ALS) has established that the formation and accumulation of aldehydes resulting from mitochondrial dysfunction and consequent excessive lipid peroxidation are extremely neurotoxic and are associated with the appearance of symptoms and progression of ALS in preclinical models. Among the various aldehydes, 4-hydroxy-2-nonenal (4-HNE), originated from the oxidation of phospholipids present in the inner membrane of mitochondria, is accumulated in the cerebrospinal fluid of patients with sporadic ALS. This electrophilic aldehyde is capable of attacking nucleophilic amino acids and forming adducts with proteins, resulting in the inactivation of target proteins, formation of protein aggregates and consequent cellular disarrangement/dysfunction. Among the main enzymes responsible for the elimination of 4-HNE and other short-chain aliphatic aldehydes, aldehyde dehydrogenase 2 (ALDH2) stands out, located in the mitochondrial matrix. Studies by our group have recently demonstrated that the sustained activation of ALDH2 through the administration of Alda-1, an allosteric agonist of the enzyme, was sufficient to reduce the levels of 4-HNE-protein adducts, protect mitochondrial bioenergetic metabolism and improve the prognosis of degenerative diseases in different animal models including heart failure, peripheral arterial disease and Alzheimer's disease.Considering the critical role of aldehydes in the progression of ALS, and the lack of effective therapies in the treatment of the disease, we hypothesize that the selective activation of the ALDH2 enzyme, and consequent removal of 4-HNE, will lead to an improvement in the mitochondrial bioenergetic profile and balance redox of neurons present in the motor cortex, spinal cord and skeletal muscle resulting in the prevention or delay of the progression of ALS.In order to better understand the role of aldehyde metabolism by ALDH2 in ALS, we propose in the present research project to test the contribution of pharmacological activation (AD6626) of ALDH2 in the progression of ALS. For a better understanding of the therapeutic role of ALDH2 enzyme activation in ALS, we will evaluate a series of functional, morphological and biochemical parameters in different tissues, including motor cortex, spinal cord, skeletal muscle and serum from wild animals and SOD1-G93A mutants in the stages asymptomatic (day 80 of life) and symptomatic (day 87 and 180 of life) of the disease. Treatments with vehicle or AD6626 (selective activator of ALDH2) will be performed by gavage (40mg/kg - twice a day) and will last for 6 weeks, starting in the symptomatic phase of the disease (day 87 of life). To evaluate the locomotor functional parameters, we will perform the open field, rotarod, ambulation, Y-maze, wire hang and grip strength tests in the animals. Among the biochemical parameters, we will analyze protein expression and catalytic activity of ALDH2, formation of 4-HNE-protein adducts, SOD1 aggregates and mitochondrial bioenergetic metabolism (including O2 consumption and H2O2 release). These measurements will be performed in wild animals and ALS carriers treated with vehicle or AD6626. This study is of great value since a more detailed understanding of the role of ALDH2 in ALS may contribute to the future use of therapies that act on key mechanisms involved in the pathophysiology of ALS, such as the ALDH2 activator (AD6626). For this project, we will count on the collaboration of Profs. Daria Mochly-Rosen and Che-Hong Chen, both from Stanford University, CA-USA; Researcher Vanessa Zambelli (Butantan Institute) and Prof. Patricia Chakur Brum, EEFE-USP.