IGS-2.7: un nuevo inhibidor de la Caseína quinasa-1δ para el tratamiento de la ELA

Abstract

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease which is characterized by a progressive muscular paralysis due to upper and lower motoneurons degeneration. Even though it currently has no curative treatment, there are two approved symptomatic treatments for the disease, being those Riluzole and Edaravone. The diagnosis is difficult since it depends on the disease progression. However, there are some criteria to help with the diagnoses. Over 90% of the cases develope a TDP-43 (transactive response DNA binding protein 43 kDa) protein pathology related to the hyperphosphorylation and ubiquitination of the protein along with protein mislocalization, leading to an abnormal aggregation in the cytoplasm. The main kinase involved in TDP-43 hyperphosphorylation is CK-1δ (casein kinase 1 isoform δ). However, there is no evidence of TDP-43 proteinopathology in patients with mutated SOD1 (superoxide dismutase 1) gene (SOD1-ALS), who show SOD1 protein aggregates rather than TDP-43 aggregates. Being a multisystemic disease makes it complicated to find reliable models to study the disease. The use of lymphoblastoid cell lines (LCLs) in this project will aim to prove the validity of these cells as a model of physiopathological study. These LCLs have been obtained from sporadic ALS (sALS) and SOD1-ALS patients blood. The effects on cellular functions in response to a CK-1δ inhibitor (IGS-2.7) will be analyzed throughout the project. The capability of IGS-2.7 to restore TDP-43 homeostasis will also be studied. The expression of phosphorylated TDP-43 was evaluated on sALS and SOD1-ALS LCLs by western blot. TDP-43 mislocalization was observed on sALS LCLs using confocal laser scanning microscopy. The cellular functions were analyzed via different studies, including viability assays, oxygen consumption rate, extracellular acidification rate and metabolism studies. The results show that the LCLs are an adequate experimental model since they recapitulate the main alterations which have been observed in affected motoneurons. LCLs from sALS patients display a significantly increased phosphorylation of TDP-43. The treatment of LCLs with IGS-2.7 does not significantly alter cell viability nor metabolism but it normalizes the phosphorylation state of TDP-43 and prevents its mislocalization on treated sALS LCLs. Additionally, the treatment with IGS-2.7 restores the decreased reserve respiratory capacity of both sALS and SOD1-ALS LCLs.