Administration of Pgk1 missense mutation leads to more effective mitigation of neurodegenerative effects observed in ALS mice and transgenic zebrafish

Amyotrophic lateral sclerosis (ALS) is characterized by progressive degeneration of motor neurons (MNs) with few available therapeutic options. Previous ALS studies demonstrated a decrease in phosphoglycerate kinase 1 (Pgk1) secreted from NogoA-overexpressing muscle cells, thus reducing interaction between extracellular Pgk1 (ePgk1) and neural membranous Enolase 2 (Eno2) with consequent inhibition of neurite outgrowth of MNs (NOMN). The negatively charged 419th aspartic acid of receptor Eno2 (Eno2-D419) is a critical residue interacting with the positively charged 353rd lysine of ligand ePgk1-K353. To strengthen the charge attraction, we mutated ePgk1-K353 to arginine (ePgk1-K353R). Compared to wild-type Pgk1, supplementary mutant Pgk1-K353R proved more effective in increasing NOMN derived from NSC34 neural cells cultured in Sol8-vector condition medium. In vivo, Pgk1-K353R-immersed zebrafish embryos exhibited increased caudal primary MNs branching. Intravenous injection of Pgk1-K353R into ALS-mice exhibited more preservative in innervated neuromuscular junctions in gastrocnemius muscle and diaphragm, increased grip strength, higher rearing frequency, 1.6-fold greater locomotive distance and longer survival. For example, median survival days for the control, Pgk1 and Pgk1-K353R groups were 131, 137.5 and 148, respectively. Collectively, we found a single-amino-acid mutant Pgk1-K353R that exhibits higher efficacy to ameliorate neurodegeneration in ALS-mice by delaying disease progression compared to that driven by wild-type Pgk1. We suggest this outcome might be due to more electrostatic attraction between ePgk1-K353R and Eno2-D419 region predicted by in silico analysis. Therefore, mutant Pgk1-K353R protein should be considered a promising neuroprotective drug for ALS treatment.