Dash Biplab Kumar, Urano Yasuomi, Mita Yuichiro, Ashida Yuki, Hirose Ryoma, Noguchi Noriko
Systems Life Sciences Laboratory, Graduate School of Life and Medical Sciences, Doshisha University, Kyotanabe 610-0394, Kyoto, Japan.
Systems Life Sciences Laboratory, Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe 610-0394, Kyoto, Japan.
Proc Natl Acad Sci U S A. 2025 May 13;122(19):e2414790122. doi: 10.1073/pnas.2414790122. Epub 2025 May 6.
PARK7/DJ-1, a redox-sensitive protein implicated in neurodegeneration, cancer, and inflammation, exhibits increased secretion under stress. We previously demonstrated that, as a leaderless protein, PARK7 relies on an unconventional autophagy pathway for stress-induced secretion. The current study delves deeper into the mechanisms governing PARK7 secretion under oxidative stress triggered by the neurotoxin 6-hydroxydopamine (6-OHDA). Here, we revealed that 6-OHDA-induced autophagic flux is critical for PARK7 secretion. Downregulation of syntaxin 17 (STX17), a SNARE protein crucial for autophagosome-lysosome fusion and cargo degradation, hindered PARK7 secretion. Likewise, impairing lysosomal function with bafilomycin A1 (BafA1) or chloroquine (CQ) diminished PARK7 release, highlighting the importance of functional lysosomes, potentially in the form of secretory autolysosomes, in PARK7 release. We also found that 6-OHDA appeared to promote the unfolding of PARK7, allowing its selective recognition by the chaperone HSPA8 via KFERQ-like motifs, leading to PARK7 translocation to the lysosomal membrane through LAMP2 via chaperone-mediated autophagy (CMA). Additionally, a dedicated SNARE complex comprising Qabc-SNAREs (STX3/4, VTI1B, and STX8) and R-SNARE SEC22B mediates the fusion of PARK7-containing autolysosomes with the plasma membrane, facilitating the extracellular release of PARK7. Hence, this study uncovers a mechanism where 6-OHDA-induced autophagic flux drives the unconventional secretion of PARK7, involving CMA for PARK7 translocation to lysosomes and specialized SNARE complexes for membrane fusion events.
PARK7/DJ-1是一种与神经退行性变、癌症和炎症相关的氧化还原敏感蛋白，在应激状态下其分泌会增加。我们之前证明，作为一种无信号肽的蛋白，PARK7依赖非传统自噬途径进行应激诱导的分泌。当前研究更深入地探究了在神经毒素6-羟基多巴胺（6-OHDA）引发的氧化应激下，调控PARK7分泌的机制。在此，我们揭示了6-OHDA诱导的自噬流对PARK7分泌至关重要。Syntaxin 17（STX17）是一种对自噬体-溶酶体融合及货物降解至关重要的SNARE蛋白，其下调会阻碍PARK7分泌。同样，用巴弗洛霉素A1（BafA1）或氯喹（CQ）损害溶酶体功能会减少PARK7释放，这突出了功能性溶酶体（可能以分泌性自噬溶酶体的形式）在PARK7释放中的重要性。我们还发现，6-OHDA似乎促进了PARK7的去折叠，使其通过类KFERQ基序被伴侣蛋白HSPA8选择性识别，进而通过伴侣介导的自噬（CMA）导致PARK7经LAMP2转运至溶酶体膜。此外，一个由Qabc-SNAREs（STX3/4、VTI1B和STX8）和R-SNARE SEC22B组成的特定SNARE复合体介导含PARK7的自噬溶酶体与质膜的融合，促进PARK7的胞外释放。因此，本研究揭示了一种机制，即6-OHDA诱导的自噬流驱动PARK7的非传统分泌，这涉及CMA介导PARK7转运至溶酶体以及特定SNARE复合体参与膜融合事件。
