PTK2-mediated degradation of ATG3 impedes cancer cells susceptible to DNA damage treatment.

Abstract

ATG3 (autophagy-related 3) is an E2-like enzyme essential for autophagy; however, it is unknown whether it has an autophagy-independent function. Here, we report that ATG3 is a relatively stable protein in unstressed cells, but it is degraded in response to DNA-damaging agents such as etoposide or cisplatin. With mass spectrometry and a mutagenesis assay, phosphorylation of tyrosine 203 of ATG3 was identified to be a critical modification for its degradation, which was further confirmed by manipulating ATG3Y203E (phosphorylation mimic) or ATG3Y203F (phosphorylation-incompetent) in Atg3 knockout MEFs. In addition, by using a generated phospho-specific antibody we showed that phosphorylation of Y203 significantly increased upon etoposide treatment. With a specific inhibitor or siRNA, PTK2 (protein tyrosine kinase 2) was confirmed to catalyze the phosphorylation of ATG3 at Y203. Furthermore, a newly identified function of ATG3 was recognized to be associated with the promotion of DNA damage-induced mitotic catastrophe, in which ATG3 interferes with the function of BAG3, a crucial protein in the mitotic process, by binding. Finally, PTK2 inhibition-induced sustained levels of ATG3 were able to sensitize cancer cells to DNA-damaging agents. Our findings strengthen the notion that targeting PTK2 in combination with DNA-damaging agents is a novel strategy for cancer therapy.

• Authors: Ke Ma, Wan Fu, Ming Tang, Chaohua Zhang, Tianyun Hou, Ran Li, Xiaopeng Lu, Yanan Wang, Jingyi Zhou, Xue Li, Luyao Zhang, Lina Wang, Ying Zhao, Wei-Guo Zhu
• Journal: Autophagy (Autophagy) Vol. 13 Issue 3 Pg. 579-591 (Mar 04 2017) ISSN: 1554-8635 [Electronic] United States
• PMID: 28103122 (Publication Type: Journal Article)

Chemical References

• Adaptor Proteins, Signal Transducing
• Apoptosis Regulatory Proteins
• Autophagy-Related Proteins
• BAG3 protein, human
• Etoposide
• Ubiquitin-Conjugating Enzymes
• Focal Adhesion Kinase 1
• PTK2 protein, human
• ATG3 protein, human

Topics

• Adaptor Proteins, Signal Transducing (metabolism)
• Animals
• Apoptosis Regulatory Proteins (metabolism)
• Autophagy-Related Proteins (metabolism)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• DNA Damage
• Etoposide (pharmacology)
• Focal Adhesion Kinase 1 (metabolism)
• Mice
• Mice, Knockout
• Mitosis (drug effects)
• Neoplasms (metabolism, pathology)
• Phosphorylation (drug effects)
• Proteolysis (drug effects)
• Ubiquitin-Conjugating Enzymes (metabolism)