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.
Lee et al. (Fri,) studied this question.