Elucidation of the influence of the CaV2.2 calcium channel on ALS disease progression in the SOD1*G93A mouse model.

Amyotrophic lateral sclerosis (ALS) is a late-onset, fatal neurodegenerative disease affecting upper and lower motor neurons in the central nervous system. Drugs like riluzole, edaravone, and tofersen treat disease symptoms or are designed for a specific pathological mutation (e.g., SOD1), but they cannot prevent or halt the disease. For this reason, the search for new therapeutic strategies continues. The voltage-gated calcium channel CaV2.2 might be a novel target in ALS treatment as the channel was shown to be overexpressed in murine SOD1*G93A cortical neurons, resulting in higher mortality. Further, murine SOD1*G93A motor neurons showed increased calcium currents mainly by an increased expression of the CaV2.2 channel. In addition, inhibition of the channel was hypothesized as mode of action for the all-d-enantiomeric peptide RD2RD2, a novel drug candidate for the treatment of ALS, which already demonstrated its efficacy in SOD1*G93A mice. To investigate the influence of the CaV2.2 channel on the progression of disease symptoms in the SOD1*G93A mouse model, a new double-transgenic line was created, combining the ALS phenotype with a knockout of the CaV2.2 channel. The study showed that the CaV2.2 knockout on the SOD1*G93A background led to reduced SHIRPA and splay scores, and a delayed disease onset. Additionally, differences were detected between wildtype and single-transgenic CaV2.2 knockout mice. However, survival was not affected. Post mortem analysis of human tissue found more CaV2.2 in ALS cases in comparison to healthy control subjects confirming involvement of the channel in human ALS. These results indicate that the CaV2.2 calcium channel may play an influential role in early disease progression of ALS.