Mechanistic description
PINK1 loss-of-function prevents Parkin recruitment to damaged mitochondria, blocking mitophagy. Urolithin A is proposed as a mitochondrial-targeted activator. Major limitations include urolithin A’s lack of specificity for the PINK1/Parkin pathway (induces general autophagy via PGC-1α/AMPK/Nrf2), failure of PINK1 knockout mice to recapitulate human PD phenotype, and uncertain applicability to idiopathic PD when PINK1/PRKN mutations cause only ~2-3% of cases.
Evidence for (3)
PINK1 and PRKN mutations cause autosomal recessive early-onset PD
PINK1-deficient flies show mitochondrial dysfunction rescued by Parkin overexpression
Urolithin A enhances mitophagy and extends lifespan in C. elegans
Evidence against (3)
Urolithin A activates general autophagy, not specifically PINK1/Parkin pathway
PINK1 knockout mice do not show robust dopaminergic neuron loss seen in humans
PINK1/Parkin mutations cause <2% of PD—limited applicability to idiopathic PD