Tumor Suppressor Spred2 Interaction with LC3 Promotes Autophagosome Maturation and Induces Autophagy-Dependent Cell Death

Authors

Ke Jiang, Dalian Medical University, China
Min Liu, Dalian Medical University, China
Guibin Lin, Dalian Medical University, China
Beibei Mao, Chinese Academy of Sciences, China
Wei Cheng, Dalian Medical University, China
Han Liu, Dalian Medical University, China
Jozsef Gal, University of KentuckyFollow
Haining Zhu, University of KentuckyFollow
Zengqiang Yuan, Chinese Academy of Sciences, China
Wuguo Deng, Dalian Medical University, China
Quentin Liu, Dalian Medical University, China
Peng Gong, Dalian Medical University, China
Xiaolin Bi, Dalian Medical University, China
Songshu Meng, Dalian Medical University, China

Abstract

The tumor suppressor Spred2 (Sprouty-related EVH1 domain-2) induces cell death in a variety of cancers. However, the underlying mechanism remains to be elucidated. Here we show that Spred2 induces caspase-independent but autophagy-dependent cell death in human cervical carcinoma HeLa and lung cancer A549 cells. We demonstrate that ectopic Spred2 increased both the conversion of microtubule-associated protein 1 light chain 3 (LC3), GFP-LC3 puncta formation and p62/SQSTM1 degradation in A549 and HeLa cells. Conversely, knockdown of Spred2 in tumor cells inhibited upregulation of autophagosome maturation induced by the autophagy inducer Rapamycin, which could be reversed by the rescue Spred2. These data suggest that Spred2 promotes autophagy in tumor cells. Mechanistically, Spred2 co-localized and interacted with LC3 via the LC3-interacting region (LIR) motifs in its SPR domain. Mutations in the LIR motifs or deletion of the SPR domain impaired Spred2-mediated autophagosome maturation and tumor cell death, indicating that functional LIR is required for Spred2 to trigger tumor cell death. Additionally, Spred2 interacted and co-localized with p62/SQSTM1 through its SPR domain. Furthermore, the co-localization of Spred2, p62 and LAMP2 in HeLa cells indicates that p62 may be involved in Spred2-mediated autophagosome maturation. Inhibition of autophagy using the lysosomal inhibitor chloroquine, reduced Spred2-mediated HeLa cell death. Silencing the expression of autophagy-related genes ATG5, LC3 or p62 in HeLa and A549 cells gave similar results, suggesting that autophagy is required for Spred2-induced tumor cell death. Collectively, these data indicate that Spred2 induces tumor cell death in an autophagy-dependent manner.

Document Type

Article

Publication Date

3-25-2016

Notes/Citation Information

Published in Oncotarget, v. 7, no. 18, p. 25652-25667.

Licensed under a Creative Commons Attribution 3.0 License.

Digital Object Identifier (DOI)

https://doi.org/10.18632/oncotarget.8357

Funding Information

This work was supported by the National Science Foundation of China (81372471 and 81572707 to SM, 31271480 to XB, 81125010 to ZY).

Repository Citation

Jiang, Ke; Liu, Min; Lin, Guibin; Mao, Beibei; Cheng, Wei; Liu, Han; Gal, Jozsef; Zhu, Haining; Yuan, Zengqiang; Deng, Wuguo; Liu, Quentin; Gong, Peng; Bi, Xiaolin; and Meng, Songshu, "Tumor Suppressor Spred2 Interaction with LC3 Promotes Autophagosome Maturation and Induces Autophagy-Dependent Cell Death" (2016). Molecular and Cellular Biochemistry Faculty Publications. 93.
https://uknowledge.uky.edu/biochem_facpub/93