Autophagy is an important cell recycling program responsible for the clearance of damaged or long-lived proteins and organelles. Pharmacological modulators of this pathway have been extensively utilized in a wide range of basic research and pre-clinical studies. Bafilomycin A1 and chloroquine are commonly used compounds that inhibit autophagy by targeting the lysosomes but through distinct mechanisms. Since it is now clear that mitochondrial quality control, particularly in neurons, is dependent on autophagy, it is important to determine whether these compounds modify cellular bioenergetics. To address this, we cultured primary rat cortical neurons from E18 embryos and used the Seahorse XF96 analyzer and a targeted metabolomics approach to measure the effects of bafilomycin A1 and chloroquine on bioenergetics and metabolism. We found that both bafilomycin and chloroquine could significantly increase the autophagosome marker LC3-II and inhibit key parameters of mitochondrial function, and increase mtDNA damage. Furthermore, we observed significant alterations in TCA cycle intermediates, particularly those downstream of citrate synthase and those linked to glutaminolysis. Taken together, these data demonstrate a significant impact of bafilomycin and chloroquine on cellular bioenergetics and metabolism consistent with decreased mitochondrial quality associated with inhibition of autophagy.
Autophagy inhibition decreased mitochondrial bioenergetics in intact neurons.
Autophagy inhibition decreased mitochondrial complexes I, II or IV substrate linked respiration.
Autophagy inhibition increased mitochondrial DNA damage.
Autophagy inhibition decreased major components of the Krebs cycle.
Autophagy inhibition resulted in decreased citrate synthase activities.