RTKN-1/Rhotekin shields endosome-associated F-actin from disassembly to ensure endocytic recycling

Yanling Yan, Shuai Liu, Can Hu, Chaoyi Xie, Linyue Zhao, Shimin Wang, Wenjuan Zhang, Zihang Cheng, Jinghu Gao, Xin Fu, Zhenrong Yang, Xianghong Wang (+3 others)
2021 Journal of Cell Biology  
Cargo sorting and the subsequent membrane carrier formation require a properly organized endosomal actin network. To better understand the actin dynamics during endocytic recycling, we performed a genetic screen in C. elegans and identified RTKN-1/Rhotekin as a requisite to sustain endosome-associated actin integrity. Loss of RTKN-1 led to a prominent decrease in actin structures and basolateral recycling defects. Furthermore, we showed that the presence of RTKN-1 thwarts the actin disassembly
more » ... ompetence of UNC-60A/cofilin. Consistently, in RTKN-1–deficient cells, UNC-60A knockdown replenished actin structures and alleviated the recycling defects. Notably, an intramolecular interaction within RTKN-1 could mediate the formation of oligomers. Overexpression of an RTKN-1 mutant form that lacks self-binding capacity failed to restore actin structures and recycling flow in rtkn-1 mutants. Finally, we demonstrated that SDPN-1/Syndapin acts to direct the recycling endosomal dwelling of RTKN-1 and promotes actin integrity there. Taken together, these findings consolidated the role of SDPN-1 in organizing the endosomal actin network architecture and introduced RTKN-1 as a novel regulatory protein involved in this process.
doi:10.1083/jcb.202007149 pmid:33844824 fatcat:py3gpwo6vbh7bgaqspabr5shoi