ARL3 subcellular localization and its suspected role in autophagy

ADP-ribosylation factor-like3 (ARL3) is a member of the ADP-ribosylation factor family of GTP-binding proteins that plays important role in regulating Ciliary trafficking. It ubiquitously expressed in normal tissues and tumor cell lines. However, the location and function of ARL3 in organelles are rarely known. In this study, we explored ARL3 subcellular localization in an all-round way in HEK293T, Neuro-2A and U251 cells by density gradient centrifugation and immunofluorescence. The results showed that ARL3 is expressed in most of organelles, and an iodixonal step gradient was further confirmed that ARL3 is mainly localized to the mitochondria, endosomes, lysosomes, and proteasome. By molecular functional analysis, we observed that ARL3 promotes the aggregation of GFP-LC3, up-regulation of LC3-II/LC3-I and down-regulation of SQSMT1/BECN1, and knocking down of ARL3 inbibits autophagy, which suggested that ARL3 is necessary for autophagy. this study presents a comprehensive evaluation of the subcellular localization for ARL3 and provides important on understanding the functions of ARL3.