A reduced removal of dysfunctional mitochondria is common to aging and age-related neurodegenerative pathologies such as Alzheimer’s disease (AD). Strategies for treating such impaired mitophagy would benefit from the identification of mitophagy modulators. Here we report the combined use of unsupervised machine learning (involving vector representations of molecular structures, pharmacophore fingerprinting and conformer fingerprinting) and a cross-species approach for the screening and experimental validation of new mitophagy-inducing compounds. From a library of naturally occurring compounds, the workflow allowed us to identify 18 small molecules, and among them two potent mitophagy inducers (Kaempferol and Rhapontigenin). In nematode and rodent models of AD, we show that both mitophagy inducers increased the survival and functionality of glutamatergic and cholinergic neurons, abrogated amyloid-β and tau pathologies, and improved the animals’ memory. Our findings suggest the existence of a conserved mechanism of memory loss across the AD models, this mechanism being mediated by defective mitophagy. The computational–experimental screening and validation workflow might help uncover potent mitophagy modulators that stimulate neuronal health and brain homeostasis.

Metabolic dysfunction is a primary feature of Werner syndrome (WS), a human premature aging disease caused by mutations in the gene encoding the Werner (WRN) DNA helicase. WS patients exhibit severe metabolic phenotypes, but the underlying mechanisms are not understood, and whether the metabolic deficit can be targeted for therapeutic intervention has not been determined. Here we report impaired mitophagy and depletion of NAD⁺, a fundamental ubiquitous molecule, in WS patient samples and WS invertebrate models. WRN regulates transcription of a key NAD⁺ biosynthetic enzyme nicotinamide nucleotide adenylyltransferase 1 (NMNAT1). NAD⁺ repletion restores NAD⁺ metabolic profiles and improves mitochondrial quality through DCT-1 and ULK-1-dependent mitophagy. At the organismal level, NAD⁺ repletion remarkably extends lifespan and delays accelerated aging, including stem cell dysfunction, in Caenorhabditis elegans and Drosophila melanogaster models of WS. Our findings suggest that accelerated aging in WS is mediated by impaired mitochondrial function and mitophagy, and that bolstering cellular NAD⁺ levels counteracts WS phenotypes.

DNA repair ensures genomic stability to achieve healthy ageing, including cognitive maintenance. Mutations on genes encoding key DNA repair proteins can lead to diseases with accelerated ageing phenotypes. Some of these diseases are xeroderma pigmentosum group A (XPA, caused by mutation of XPA), Cockayne syndrome group A and group B (CSA, CSB, and are caused by mutations of CSA and CSB, respectively), ataxia-telangiectasia (A-T, caused by mutation of ATM), and Werner syndrome (WS, with most cases caused by mutations in WRN). Except for WS, a common trait of the aforementioned progerias is neurodegeneration. Evidence from studies using animal models and patient tissues suggests that the associated DNA repair deficiencies lead to depletion of cellular nicotinamide adenine dinucleotide (NAD⁺), resulting in impaired mitophagy, accumulation of damaged mitochondria, metabolic derailment, energy deprivation, and finally leading to neuronal dysfunction and loss. Intriguingly, these features are also observed in Alzheimer’s disease (AD), the most common type of dementia affecting more than 50 million individuals worldwide. Further studies on the mechanisms of the DNA repair deficient premature ageing diseases will help to unveil the mystery of ageing and may provide novel therapeutic strategies for AD.

ULK1 (Atg1) initiates macroautophagy and mitophagy, which support neuronal growth and survival, yet how this pathway is disrupted in aging and Alzheimer's disease (AD) remains unclear. Here we report reduced ULK1 in serum and cerebrospinal fluid during aging in cognitively unimpaired participants from the COGNORM study (n = 75) and in patients with AD from the NorCog Memory Clinic Cohort (n = 316). In AD mice, ULK1 overexpression stimulates autophagic flux, reduces AD pathology and delays cognitive decline alongside increased phagocytic degradation of amyloid-β, reduced tauopathy and improved mitochondrial quality. Mechanistically, ULK1 upregulation increases autophagy and PINK1-, FUNDC1- and AMBRA1-associated mitophagy; higher autophagy and mitophagy increase cellular NAD⁺, which in turn deacetylates acetylated-Tau174 via the NAD⁺-SIRT1 axis, leading to reduced tauopathy. Using in vitro tau seeding assays and a Caenorhabditis elegans tau model, we validate the efficacy of ULK1 activators in inhibiting tauopathy. We propose that age-related decline in ULK1 leads to autophagy and mitophagy impairment and increases the progression of AD and identify ULK1 as a potential therapeutic target.