N-terminal hexokinase 1 peptide against mitochondrial dysfunction in amyotrophic lateral sclerosis: an in vitro and in iPS cells study

Mitochondrial dysfunction represents an early event in degeneration of spinal cord’s motor neurons in genetic and sporadic Amyotrophic Lateral Sclerosis (ALS). Mutations in gene encoding for the  antioxidant enzyme Superoxide Dismutase 1 (SOD1) are considered one of the most common cause of ALS, and more than 160 SOD1 mutants have been discovered so far. In the last decade, it was shown that the dismutase-active SOD1 G93A mutant forms toxic aggregates onto the cytosolic surface of mitochondria, using the Voltage Dependent Anion Channel isoform 1 (VDAC1) as docking site. In healthy cells, VDAC1 mediates the metabolic exchanges between cytosol and mitochondria and regulates cell life and death. In ALS affected motor neurons, SOD1 G93A binds to VDAC1 and strongly affects the channel conductance, promoting the organelle’s degeneration. However, VDAC1 is the physiological receptor of Hexokinase 1 (HK1), whose levels in spinal cord were found lower compared to brain. Our preliminary results show that SOD1 G93A competes with HK1 for the same VDAC1 binding site(s). Moreover, a small peptide based on N-terminal HK1 domain (NHK1) is able to specifically interact with VDAC1, inhibiting its interaction with SOD1 G93A. In addition, NHK1 peptide shows the ability to ameliorate cell survival and mitochondrial membrane potential of motorneuronal cells NSC34 expressing SOD1 G93A. Here we propose to analyze the effect of NHK1 peptide on the interaction of VDAC1 with others SOD1 mutants, such as G85R or A4V, by using an in vitro and in cellulo approach. As cellular model mimicking the ALS phenotype, we propose the use of induced Pluripotent Staminal cells (iPSc), directly derived from genetic and sporadic ALS patients expressing SOD1 mutants. The general goal of this project is the validation of the use of our interfering peptide as therapeutic tool in mitochondrial dysfunction of ALS motor neurons.