https://orcid.org/0000-0003-1141-2943
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ABSTRACT
Macroautophagy/autophagy is a catabolic process crucial for degrading cytosolic components and damaged organelles to maintain cellular homeostasis, enabling cells to survive in extreme extracellular environments. ENAH/MENA, a member of the Ena/VASP protein family, functions as a highly efficient actin elongation factor. In this study, our objective was to explore the role of ENAH in the autophagy process. Initially, we demonstrated that depleting ENAH in cancer cells inhibits autophagosome formation. Subsequently, we observed ENAH’s colocalization with MAP1LC3/LC3 during tumor cell starvation, dependent on actin cytoskeleton polymerization and the interaction between ENAH and BECN1 (beclin 1). Additionally, mammalian ATG9A formed a ring-like structure around ENAH-LC3 puncta during starvation, relying on actin cytoskeleton polymerization. Furthermore, ENAH’s EVH1 and EVH2 domains were found to be indispensable for its colocalization with LC3 and BECN1, while the PRD domain played a crucial role in the formation of the ATG9A ring. Finally, our study revealed ENAH-led actin comet tails in autophagosome trafficking. In conclusion, our findings provide initial insights into the regulatory role of the mammalian actin elongation factor ENAH in autophagy.
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| 3-MA | = | 3-methyladenine |
| ABPs | = | actin-binding proteins |
| ATG | = | autophagy related |
| ATG9A | = | autophagy related 9A |
| Baf A1 | = | bafilomycin A1 |
| CM | = | complete medium |
| CytERM | = | endoplasmic reticulum signal-anchor membrane protein |
| Cyto D | = | cytochalasin D |
| EBSS | = | Earl’s balanced salt solution |
| ENAH/MENA | = | ENAH actin regulator |
| EVH1 | = | Ena/VASP homology 1 domain |
| EVH2 | = | Ena/VASP homology 2 domain |
| GAPDH | = | glyceraldehyde-3-phosphate dehydrogenase |
| Lat B | = | latrunculin B |
| LC3-I | = | unlipidated form of LC3 |
| LC3-II | = | phosphatidylethanolamine-conjugated form of LC3 |
| MAP1LC3/LC3 | = | microtubule associated protein 1 light chain 3 |
| mEGFP | = | monomeric enhanced green fluorescent protein |
| mTagBFP2 | = | monomeric Tag blue fluorescent protein 2 |
| OSER | = | organized smooth endoplasmic reticulum |
| PRD | = | proline-rich domain |
| PtdIns3K | = | class III phosphatidylinositol 3-kinase |
| WM | = | wortmannin. |
Acknowledgments
Thanks to the technique support from Analytical and Testing Center of School of Pharmacy, Fudan University.
Disclosure statement
The authors declare that they have no competing interests.