Persistent Zn2+ Influx‐Mediated Deacetylation of ANXA2 Regulates the “Zn2+‐Autophagic Flux” and Alleviates Intervertebral Disc Degeneration

Abstract

ABSTRACT Intervertebral disc degeneration (IVDD) is an age‐related disease accompanied by disrupted mitochondrial homeostasis and defective autophagy. Cellular senescence induces ion imbalance, which leads to mitochondrial damage and suppressed autophagic flux; nevertheless, the molecular mechanism underlying this process remains poorly understood. Here, by integrating single‐cell RNA sequencing (single‐cell RNA‐seq), messenger RNA sequencing (mRNA‐seq), and liquid chromatography‐mass spectrometry (LC‐MS), we identified zinc transporter ZIP14 (SLC39A14) as a critical regulatory factor. Further investigations revealed that deacetylation at lysine 302 (K302) of annexin A2 (ANXA2) serves as a core intracellular zinc‐dependent regulatory node controlling mitophagy. In vitro site‐directed mutagenesis combined with molecular dynamics simulations demonstrated that acetylation at the ANXA2 K302 residue alters the conformation and function of the ANXA2‐mTOR complex. Specifically, K302 acetylation enhances the interaction between ANXA2 and mTOR, consequently restraining cellular mitophagy. Mechanistically, zinc‐dependent modification of ANXA2 governs mTOR activity, bridging disturbed ion homeostasis and autophagy machinery. We also characterized the intracellular degradation pattern of ANXA2 and clarified its abnormal accumulation during IVDD development. In vivo experiments verified that ZIP14 (SLC39A14) is required to maintain intracellular Zn2 + levels and sustain ANXA2‐mTOR signaling. Consistently, dietary zinc supplementation effectively slows IVDD progression, highlighting a potential therapeutic strategy.