Astrocytic metabolic switch is a novel etiology for Cocaine and HIV-1 Tat-mediated neurotoxicity

Calcium (Ca(2+)) dynamics and oxidative signaling control mitochondrial bioenergetics in the central nervous system, where astrocytes are a major energy source for neurons. Cocaine use exacerbates HIV-associated neurocognitive disorders, but little is known about disruptions in astrocyte metabolism in this context. Our data show that the HIV protein Tat and cocaine induce a metabolic switch from glucose to fatty acid oxidation in astrocytes, thereby limiting lactate transport to neurons. Mechanistic analyses revealed increased Mitochondrial Ca(2+) Uniporter (MCU)-mediated Ca(2+) uptake in astrocytes exposed to Tat and cocaine due to oxidation of MCU. Since our data suggest that mitochondrial oxidation is dependent in part on MCU-mediated Ca(2+) uptake, we targeted MCU to restore glycolysis in astrocytes to normalize extracellular lactate levels. Knocking down MCU in astrocytes prior to Tat and cocaine exposure prevented metabolic switching and protected neurons. These findings identify a novel molecular mechanism underlying neuropathogenesis in HIV and cocaine use.