Autophagy Failure in Brain Support Cells Accelerates Cognitive Aging

Why it matters: Brain aging involves not just neuronal decline but deterioration of supporting glial cells. Oligodendrocyte precursor cells (OPCs) are the most proliferative glial population in the adult brain and have recently emerged as regulators of synaptic function. This study reveals a previously unrecognized mechanism by which OPC dysfunction—specifically failed macroautophagy—drives cognitive aging through non-cell-autonomous senescence signaling.

What was studied: The researchers generated OPC-specific Atg5 conditional knockout mice (Atg5-cKO, using PDGFRα-Cre) to selectively abolish macroautophagy in OPCs. They combined this genetic model with aged wild-type mice (18–24 months), single-cell RNA sequencing of OPCs from young versus aged brains, co-culture systems, and pharmacological interventions including the senolytic combination dasatinib plus quercetin (D+Q) and the autophagy inducer rapamycin.

Key results: Single-cell transcriptomics confirmed that OPCs from aged mouse brains display markedly reduced expression of autophagy pathway genes. Atg5-cKO mice showed p62/SQSTM1 accumulation, elevated reactive oxygen species, and nuclear NF-κB activation in OPCs—hallmarks of cellular senescence. These autophagy-deficient OPCs upregulated canonical SASP factors (IL-6, IL-1β, TNF-α, MMP-3) and entered a senescent state confirmed by SA-β-galactosidase staining, p21 and p16 upregulation, and γH2AX foci. Crucially, conditioned medium from Atg5-KO OPCs reduced dendritic spine density and suppressed AMPA receptor surface expression and LTP in cultured neurons. In vivo, Atg5-cKO mice showed impaired performance in Morris water maze and novel object recognition tests alongside reduced hippocampal spine density and LTP deficits. Senolytic treatment (D+Q) cleared senescent OPCs, rescued spine density, restored LTP, and improved cognitive performance. Rapamycin-induced autophagy enhancement in aged mice similarly reversed OPC senescence markers and cognitive deficits.

Mechanistic insights: The NF-κB pathway was identified as the central mediator linking p62 accumulation (due to impaired autophagy) to SASP production. Pharmacological NF-κB inhibition in Atg5-cKO OPCs reduced SASP secretion and partially rescued neuronal plasticity, confirming the causal chain: autophagy loss → p62 accumulation → NF-κB activation → SASP → neuronal dysfunction.

Implications and caveats: This work positions OPC autophagy as a master regulator of brain aging, acting non-cell-autonomously to control neuronal plasticity. The findings suggest that senolytics or autophagy-enhancing interventions targeting OPCs may represent viable strategies to slow cognitive decline. However, all in vivo work was conducted in rodent models, and the relative contribution of OPC senescence versus other aging mechanisms in humans remains unknown. The specificity of PDGFRα-Cre for OPCs versus other PDGFRα-expressing cells also warrants consideration.