Restoration of mitochondrial dynamics and synaptic function by mitophagy enhancers in a tauopathy cell model

To evaluate whether mitophagy enhancers-including urolithin A, actinonin, tomatidine, and nicotinamide riboside-can counteract mitochondrial dysfunction and synaptic damage induced by phosphorylated Tau in Alzheimer's disease.

We Used immortalized mouse hippocampal primary HT22 neurons expressing mutant Tau (mTau-HT22). We treated cells with mitophagy enhancers and measured gene and protein levels of mitochondrial dynamics, biogenesis, mitophagy, synaptic markers, assessed cell viability, mitochondrial respiration, and examined mitochondrial morphology via transmission electron microscopy.

Compared to controls, mTau-HT22 cells exhibited increased mitochondrial fission and reduced fusion, diminished mitochondrial biogenesis, impaired mitophagy and synaptic gene expression, reduced cell survival, lower respiration, and fragmented mitochondria. Treatment with all mitophagy-enhancing compounds improved mitochondrial dynamics-, biogenesis-, and mitophagy-related marker expression together with mitochondrial functional outcomes, with urolithin A showing the strongest effects. Notably, a combined treatment of urolithin A with EGCG further enhanced respiratory function beyond single-agent treatments.

Mitophagy enhancers, particularly urolithin A alone or in combination with EGCG, restore mitochondrial and synaptic health in Tau-induced toxicity models. These findings position mitophagy enhancement as a potential therapeutic approach requiring further validation in Alzheimer's disease.