Neuronal cell-based high-throughput screen for enhancers of mitochondrial function reveals luteolin as a modulator of mitochondria-endoplasmic reticulum coupling
Background: Mitochondrial dysfunction is a common feature of aging, neurodegeneration, and metabolic diseases.
Hence, mitotherapeutics may be valuable disease modifiers for a large number of conditions. In this study, we have
set up a large-scale screening platform for mitochondrial-based modulators with promising therapeutic potential.
Results: Using differentiated human neuroblastoma cells, we screened 1200 FDA-approved compounds and
identified 61 molecules that significantly increased cellular ATP without any cytotoxic effect. Following dose
response curve-dependent selection, we identified the flavonoid luteolin as a primary hit. Further validation in
neuronal models indicated that luteolin increased mitochondrial respiration in primary neurons, despite not
affecting mitochondrial mass, structure, or mitochondria-derived reactive oxygen species. However, we found that
luteolin increased contacts between mitochondria and endoplasmic reticulum (ER), contributing to increased
mitochondrial calcium (Ca2+) and Ca2+-dependent pyruvate dehydrogenase activity. This signaling pathway likely
contributed to the observed effect of luteolin on enhanced mitochondrial complexes I and II activities. Importantly,
we observed that increased mitochondrial functions were dependent on the activity of ER Ca2+-releasing channels
inositol 1,4,5-trisphosphate receptors (IP3Rs) both in neurons and in isolated synaptosomes. Additionally, luteolin
treatment improved mitochondrial and locomotory activities in primary neurons and Caenorhabditis elegans
expressing an expanded polyglutamine tract of the huntingtin protein.
Conclusion: We provide a new screening platform for drug discovery validated in vitro and ex vivo. In addition, we
describe a novel mechanism through which luteolin modulates mitochondrial activity in neuronal models with
potential therapeutic validity for treatment of a variety of human diseases
