Astrocytes mobilize a broader repertoire of lysosomal repair mechanisms than neurons
TL;DR
A divergence in how neurons and astrocytes mobilize repair pathways to manage lysosomal damage is revealed, which may reflect differences in lysosomal resilience between astrocytes and neurons and inform therapeutic strategies to correct lysosomal dysfunction in neurodegenerative diseases.
Abstract
Summary Lysosomal damage impairs proteostasis and contributes to neurodegenerative diseases, yet cell-type-specific differences in lysosomal repair remain unclear. Using a neuron-astrocyte coculture system, we compared responses to lysosomal injury induced by a lysosomotropic methyl ester. Both neurons and astrocytes showed lysosomal damage, marked by Galectin-3 recruitment to lumenal lysosomal β-galactosides, disrupted lysosomal pH, and engagement of lysophagy receptors TAX1BP1 and p62. However, astrocytes showed a preferential recruitment of ESCRT (endosomal sorting complex required for transport) repair machinery to damaged lysosomes. Additionally, the lysosomal membrane reformation pathway regulated by the RAB7-GTPase-activating protein (GAP), TBC1D15, was more robustly activated in astrocytes. By contrast, the phosphoinositide-initiated membrane tethering and lipid transport (PITT) pathway, mediating lipid transfer between the endoplasmic reticulum (ER) and damaged lysosomes, was engaged in both cell types. Our data reveal a divergence in how neurons and astrocytes mobilize repair pathways to manage lysosomal damage. These data may reflect differences in lysosomal resilience between astrocytes and neurons and inform therapeutic strategies to correct lysosomal dysfunction in neurodegenerative diseases.