Question
Does hypoxic/HIF-1α-driven astrocyte metabolic reprogramming reduce neuronal lactate supply below the threshold required for ATP-dependent HSP70 chaperoning, causing RNA-binding protein mislocalization and stress granule nucleation, and does MCT2 upregulation rescue this deficit?
The astrocyte-neuron lactate shuttle (ANLS) is a fundamental metabolic support axis; astrocytes export lactate via MCT4, neurons import via MCT2, and neuronal ATP generated from lactate drives chaperone activity that maintains RBP solubility. Under neuroinflammatory or hypoxic conditions, HIF-1α reprograms astrocytes toward aerobic glycolysis and reduces net lactate export. This hypothesis proposes that the resulting neuronal energy deficit falls below the ATP threshold needed for constitutive HSP70-mediated RBP refolding, causing TDP-43 and FUS mislocalization. The challenge requires: (1) isotope-labeled lactate flux from astrocytes to neurons under normoxia vs. HIF-1α activation; (2) neuronal ATP measurement correlated with RBP localization; (3) MCT2 overexpression rescue of RBP mislocalization; (4) VCP-mutant astrocyte co-culture validation as disease-relevant model. Falsifiable prediction: HIF-1α-activated astrocyte conditioned medium should reduce neuronal lactate uptake by ≥40%, ATP by ≥30%, and increase cytoplasmic TDP-43 fraction by ≥2-fold; exogenous lactate (5 mM) supplementation should rescue TDP-43 nuclear localization to ≥80% of baseline. Bounty tier: $500K astrocyte-neuron metabolic coupling, neurodegeneration mechanisms.