Mitophagy preserves overall mitochondrial fitness by selectively targeting damaged mitochondria for degradation. The regulatory mechanisms that prevent PTEN-induced putative kinase 1 (PINK1) and E3 ubiquitin ligase Parkin (PINK1/Parkin)-dependent mitophagy and other selective autophagy pathways from overreacting while ensuring swift progression once initiated are largely elusive. Here, we demonstrate how the TBK1 (TANK-binding kinase 1) adaptors NAP1 (NAK-associated protein 1) and SINTBAD (similar to NAP1 TBK1 adaptor) restrict the initiation of OPTN (optineurin)-driven mitophagy by competing with OPTN for TBK1. Conversely, they promote the progression of nuclear dot protein 52 (NDP52)-driven mitophagy by recruiting TBK1 to NDP52 and stabilizing its interaction with FIP200. Notably, OPTN emerges as the primary recruiter of TBK1 during mitophagy initiation, which in return boosts NDP52-mediated mitophagy. Our results thus define NAP1 and SINTBAD as cargo receptor rheostats, elevating the threshold for mitophagy initiation by OPTN while promoting the progression of the pathway once set in motion by supporting NDP52. These findings shed light on the cellular strategy to prevent pathway hyperactivity while still ensuring efficient progression.

线粒体自噬通过选择性地针对受损的线粒体进行降解来保持线粒体的整体健康。防止 PTEN 诱导的推定激酶 1 (PINK1) 和 E3 泛素连接酶 Parkin (PINK1/Parkin) 依赖性线粒体自噬和其他选择性自噬途径反应过度，同时确保启动后迅速进展的调节机制在很大程度上是难以捉摸的。在这里，我们演示了 TBK1（TANK 结合激酶 1）接头 NAP1（NAK 相关蛋白 1）和 SINTBAD（类似于 NAP1 TBK1 接头）如何通过与 OPTN 竞争 TBK1 来限制 OPTN (optineurin) 驱动的线粒体自噬的启动。相反，它们通过将 TBK1 招募到 NDP52 并稳定其与 FIP200 的相互作用，促进核点蛋白 52 (NDP52) 驱动的线粒体自噬的进展。值得注意的是，OPTN 在线粒体自噬启动过程中成为 TBK1 的主要招募者，这反过来又增强了 NDP52 介导的线粒体自噬。因此，我们的结果将 NAP1 和 SINTBAD 定义为货物受体变阻器，提高了 OPTN 启动线粒体自噬的阈值，同时通过支持 NDP52 启动后促进该途径的进展。这些发现揭示了防止通路过度活跃同时仍确保有效进展的细胞策略。