📋 Browse Articles

To investigate the role of PINK1/Parkin-mediated mitophagy in regulating synaptic remodeling of neuronal cells in depression-like behaviors induced by nonylphenol (NP). In vitro experiments: HT-22 neuronal cells were exposed to NP, and mitophagy and Parkin expression were inhibited using specific inhibitors. The cells were categorized into the following groups: (1) control (C) and low-dose NP group (L: 2.5 µM), medium-dose NP group (M: 50 µM), and high-dose NP groups (H: 100 µM); (2) control (C), NP (100 µM), Mdivi-1 (5 µM), and Mdivi-1 + NP (5 µM Mdivi-1 +100 µM NP) groups; (3) control (C), NP (100 µM), AC220 (2 nM), and AC220 + NP (2 nM AC220 +100 µM NP) groups. In vivo experiments: a total of 48 mice, including 24 C57BL/6 wild-type mice and 24 PKRK2 gene-knockout mice, were randomly assigned to the following four groups: control (C), NP (100 mg/kg/day), PKRK2-knockout (KO), and PKRK2-knockout + NP (100 mg/kg/day, KH) groups, with 12 mice in each group. In vitro: With increasing NP concentration, the ATP content reduced and the expressions of synaptic remodeling-related proteins (i.e., PSD-95, BDNF, SYN) decreased. In contrast, the expressions of mitophagy-related proteins and those involved in the PINK1/Parkin-signaling pathway (such as p62, Beclin1, PINK1, Parkin) increased (P < 0.05). Inhibition of mitophagy with Mdivi-1 alleviated the NP-induced changes in synaptic, mitophagy-related, and PINK1/Parkin pathway-related proteins. Similarly, the inhibition of Parkin with AC220 mitigated NP-induced effects on synaptic, mitophagy-related, and PINK1/Parkin-signaling pathway-related proteins and mRNA expression. In vivo: PKRK2 gene-knockout mice exhibited improved NP-induced depression-like behaviors and decreased NP-induced synaptic morphology and mitochondrial ultrastructure changes. Moreover, the gene knockout alleviated the downregulation of synaptic remodeling-related proteins and inhibited the PINK1/Parkin-signaling pathway-mediated mitophagy activated by NP. Mitophagy inhibition or PKRK2 knockout can alleviate NP-induced downregulation of synaptic remodeling-related proteins, protect synaptic morphology and ultrastructure, and improve NP-induced depression-like behaviors. Show less

Decline in mitochondrial quality is a prominent pathological feature of Alzheimer's disease (AD), manifested by impaired energy metabolism, disrupted mitochondrial biogenesis, abnormal mitochondrial dynamics, and defective mitophagy. Increasing evidence indicates that mitochondrial dysfunction contributes to the exacerbation of amyloid-β (Aβ) deposition and tau protein hyperphosphorylation, thereby accelerating AD pathogenesis. Of particular interest, physical exercise has been shown to effectively enhance mitochondrial quality and help prevent or slow the progression of AD, largely through the activation of key signaling pathways such as adenosine monophosphate-activated protein kinase (AMPK) and sirtuin 1 (SIRT1). However, regular physical activity may not be feasible for individuals in the prodromal or clinical stages of AD. In this context, exercise mimetics-compounds that pharmacologically simulate the molecular effects of exercise-have emerged as a promising alternative intervention. This review analyzes the mechanistic roles of exercise mimetics in improving mitochondrial quality under AD conditions, with a focus on their regulation of mitochondrial homeostasis via key signaling pathways. It further aims to provide theoretical insight for the development of mitochondria-targeted exercise mimetics and offer a potential strategy for addressing the growing global burden of AD. Show less

PINK1-dependent activation of PRKN/parkin on depolarized mitochondria causes mitophagy. The deficiency of NME3, a nucleoside diphosphate kinase/NDPK on the outer mitochondria membrane (OMM), is associated with a fatal neurodegenerative disorder. Here, we report that NME3 deficiency impairs p-S65-ubiquitin (Ub)-dependent PRKN binding on depolarized mitochondria without involving the loss of Ub phosphorylation by PINK1. Our mechanistic investigation revealed that NME3 interacts with PLD6/MitoPLD to generate phosphatidic acid (PA) from cardiolipin on the OMM of damaged mitochondria after depolarization. This lipid signal is essential for positioning MFN2 nearby PINK1 for phosphorylation of Ub conjugates on MFN2, thus enabling the subsequent amplification of PRKN binding to mitochondria. We provide further evidence that mitochondria-endoplasmic reticulum (Mito-ER) tethering prohibits the proximity of MFN2 with PINK1 and PRKN amplification on mitochondria. Importantly, the loss of NME3-regulated PA signal causes Mito-ER tethering. Overall, our findings suggest that NME3 cooperates with PLD6 to generate PA as a critical step in Mito-ER untethering, allowing MFN2 access to PINK1 for p-S65-poly-Ub-dependent feedforward activation of PRKN. Show less