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Abstract

Macroautophagy is a lysosomal bulk degradation pathway that regulates the turnover of cytoplasmic cargo, including long-lived proteins and damaged organelles, thereby maintaining cellular homeostasis. Degradation of cytoplasmic material is mediated by cargo sequestration in autophagosomes and cargo degradation in the lysosomal compartment. Degraded monomers and energy are subsequently used for recycling purposes. The ATP-binding cassette- transporter A3 (ABCA3) was found to localize in the membranes of lamellar bodies as well as lysosomes. ABCA3 is responsible for the transport of substrates, predominantly lipids, into the inner of the organelle, however, the function of ABCA3 is insufficiently understood. In the present work we demonstrate that downregulation of ABCA3 in human U-2 OS cells leads to an elevated level of both basal and starvation-induced macroautophagy, but had no influence on chaperone-mediated autophagy. Our findings suggest a potential inhibitory role of ABCA3 in the regulatory mechanism of macroautophagy.