AP-1 Recruits SMAP-1/SMAPs to the trans-Golgi Network to Promote Sorting in Polarized Epithelia

Shimin Wang; Longfeng Yao; Wenjuan Zhang; Zihang Cheng; Can Hu; Hang Liu; Yanling Yan; Anbing Shi

doi:10.3389/fcell.2021.774401

AP-1 Recruits SMAP-1/SMAPs to the trans-Golgi Network to Promote Sorting in Polarized Epithelia

Front Cell Dev Biol. 2021 Nov 25:9:774401. doi: 10.3389/fcell.2021.774401. eCollection 2021.

Authors

Shimin Wang¹, Longfeng Yao¹, Wenjuan Zhang¹, Zihang Cheng¹, Can Hu¹, Hang Liu¹, Yanling Yan^{1

2}, Anbing Shi^{1

2}

Affiliations

¹ Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
² Cell Architecture Research Institute, Huazhong University of Science and Technology, Wuhan, China.

Abstract

Coordinated AP-1 and clathrin coat assembly mediate secretory sorting on the trans-Golgi network (TGN) during conventional secretion. Here we found that SMAP-1/SMAPs deficiency caused the apical protein ERM-1 to accumulate on the basolateral side of the TGN. In contrast, the basolateral protein SLCF-1 appeared abnormally on the apical membrane. SMAP-1 colocalized with AP-1 on the TGN. The integrity of AP-1 is required for the subcellular presence of SMAP-1. Moreover, we found that the loss of SMAP-1 reduced clathrin-positive structures in the cytosol, suggesting that SMAP-1 has a regulatory role in clathrin assembly on the TGN. Functional experiments showed that overexpressing clathrin effectively alleviated exocytic defects due to the lack of SMAP-1, corroborating the role of SMAP-1 in promoting the assembly of clathrin on the TGN. Together, our results suggested that the AP-1 complex regulates the TGN localization of SMAP-1, promoting clathrin assembly to ensure polarized conventional secretion in C. elegans intestinal epithelia.

Keywords: AP-1; C. elegans; SMAP-1/SMAPs; clathrin; intestinal epithelia; polarized sorting.