A 16-amino acid peptide delays the progression of motor neuron degeneration and pathogenic symptoms in ALS models

TL;DR

A 16-amino acid peptide delays motor neuron degeneration and improves symptoms in models of amyotrophic lateral sclerosis (ALS).

Contribution

The discovery of two 16-amino acid peptides that mimic the neuroprotective effects of full-length Pgk1 in ALS models.

Findings

FD-1 and FD-2 peptides reduce p-Cofilin and promote neurite outgrowth in ALS-like NSC34 cells.

FD peptides rescue axonal growth and motor function in zebrafish and improve survival in ALS mice.

FD peptides delay neuromuscular junction denervation and preserve motor neuron cell bodies in ALS models.

Abstract

Amyotrophic lateral sclerosis (ALS) is a progressive motor neurons (MNs) degenerative disease. Despite advancements in understanding ALS pathogenesis, drug development lags far behind. The reduced secretion of phosphoglycerate kinase 1 (Pgk1) by NogoA-overexpressing muscle cells inhibits neurite outgrowth of MNs (NOMNs). However, administration of extracellular Pgk1 (ePgk1) reduces phospho-Cofilin (p-Cofilin), a growth cone collapse marker, and mitigates MN degeneration. This improves NOMNs in NSC34 neural cells and locomotion in SOD1-G93A ALS-mice by suppressing the p-P38-T180/p-MK2-T334/p-Limk1-S323/p-Cofilin-S3 signaling pathway. Here, we identified two Pgk1-based 16-amino acid (aa) short peptides, FD-1 and FD-2, with neuroprotective effects equivalent to those of full-length ePgk1. Administration of FD-1 or FD-2 (FD-1/-2) reduced p-Cofilin and promoted NOMNs in NSC34 ​cells cultured in conditioned medium obtained from NogoA-overexpressing muscle cells. Furthermore, we found that exogenous addition of FD-1/-2 to the culture medium attenuated the accumulation of phospho-Tau-S396 and the cytoplasmic mislocalization of transactive response DNA binding protein of 43 ​kDa (TDP-43) in oxidative-stressed ALS-like SOD1-G93A NSC34 ​cells. In FD-1/-2-injected zebrafish embryos, we observed increased caudal primary MNs branching. In C9orf72-knockdown and hTDP-43-G348C mRNA overexpressing zebrafish embryos injected with FD-1/-2, axonal growth and motor function were rescued. Moreover, intravenous injection of FD-1/-2 in SOD1-G93A ALS-mice delayed denervation of neuromuscular junction, preserved cell bodies of MNs in the ventral horn of spinal cord, increased grip strength, improved locomotion and prolonged survival. Therefore, both 16-aa short FD peptides are functionally equivalent to full-length 417-aa ePgk1 and thus promising therapeutic short peptides for the treatment of ALS.

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