Recently, the Anhui Key Laboratory of Cellular Dynamics and Chemical Biology at the University of Science and Technology of China, headed by Professor YAO Xuebiao , undefined mechanism by which EGF-elicited phosphorylation of the BAR domain controls ACAP4 molecular plasticity and plasma membrane dynamics during cell migration by using functional proteomics, structure biology combined with biophotonics at nanoscale. This work was published on Proceedings of the National Academy of Sciences of the United States of America on June 17th 2013.
ArfGAP With Coiled-Coil, Ankyrin Repeat And PH Domains 4 (ACAP4) is an ADP-ribosylation factor 6 (ARF6) GTPase-activating protein essential for EGF-elicited cell migration. However, how ACAP4 regulates membrane dynamics and curvature in response to EGF stimulation is unknown. Here, we show that phosphorylation of the N-terminal region of ACAP4, named the Bin, Amphiphysin, and RSV161/167 (BAR) domain, at Tyr34 is necessary for EGF-elicited membrane remodeling. Domain structure analysis demonstrates that the BAR domain regulates membrane curvature. EGF stimulation of cells causes phosphorylation of ACAP4 at Tyr34, which subsequently promotes ACAP4 homodimer curvature. The phospho-mimicking mutant of ACAP4 demonstrates lipid-binding activity and tubulation in vitro, and ARF6 enrichment at the membrane is associated with ruffles of EGF-stimulated cells. Expression of the phospho-mimicking ACAP4 mutant promotes ARF6-dependent cell migration. Thus, the results present a previously undefined mechanism by which EGF-elicited phosphorylation of the BAR domain controls ACAP4 molecular plasticity and plasma membrane dynamics during cell migration.

EGF stimulation elicits phosphorylation of ACAP at Tyr34. HepG2 cells were cotransfected with ARF6-mCherry and ACAP4-GFP constructs. At 24 h after transfection, cells were subjected to serum starvation and EGF stimulation. Treated cells were fixed and then examined under a fluorescence microscope. (Scale bar, 10 μm.)
The joint first authors of this paper are Postdoctoral Fellow Xuannv Zhao and Dongmei Wang of Hefei National Laboratory for Physical Sciences at Nanoscale. This study was supported by the Professor Yunyu Shi and Professor Maikun Teng. This work was supported by grants from Ministry of Science and Technology of China，Ministry of Education of China, Chinese Academy of Science, Natural Science Foundation of China, Anhui Province Key Project.

http://www.pnas.org/content/early/2013/06/12/1217727110.short

　　　　　　　　  (School of Life Sciences, Department of Science and Technology)