bims-tofagi 2026-06-28 papers

Issue of 2026–06–28
seven papers selected by
Michele Frison, University of Cambridge

Autophagy. 2026 Jun 24.

Robust and sensitive ELISA detection of total and activated PRKN.

Jens O Watzlawik, Bernardo A Bustillos, Claudia Rodriguez Martinez, Dennis W Dickson, Zbigniew K Wszolek, Owen A Ross, Wolfdieter Springer, Fabienne C Fiesel.

Parkinson disease (PD) is closely linked to disruptions in mitochondrial quality control, a process regulated by the ubiquitin kinase PINK1 and the E3 ubiquitin ligase PRKN/parkin. Upon mitochondrial damage, PINK1 phosphorylates ubiquitin, which in turn recruits and activates PRKN. Full activation of PRKN is mediated by PINK1-dependent phosphorylation of PRKN at serine 65, which leads to widespread ubiquitination of mitochondrial substrates and amplifies the mitophagy response. Disruption of this pathway results in mitochondrial accumulation, oxidative stress, and neuronal death, all key mechanisms of PD pathogenesis. Genetic studies have shown biallelic loss-of-function mutations in PRKN are the most common cause of early-onset PD. Although the role of haploinsufficiency remains under investigation, PRKN protein becomes insoluble and inactive with aging or post-translational modifications, indicating that functional protein levels are a key determinant of disease risk. Reliable quantification of total and activated PRKN in samples has not been feasible, limiting research and clinical assessment. To address this, we developed and validated knockout (KO)-verified sandwich ELISA assays that quantify both total PRKN and PINK1-phosphorylated p-S65-PRKN. These assays provide absolute quantification of PRKN, improving functional diagnosis, and patient stratification in PD. Application of these methods established the concentration of PRKN in cells and in brain and revealed significant effects of a common genetic PRKN variant, further highlighting the importance of determining functional PRKN protein levels. The developed immunoassays complement previously established PINK1 and p-S65-Ub measurements, enhancing mechanistic insight into mitophagy and enabling effective monitoring of PD therapies and other neurodegenerative diseases.

Keywords: Autophagy; P-S65-PRKN; PARK2; PINK1; biomarker; mitochondria; mitophagy; parkin; parkinson disease; ubiquitin

DOI: https://doi.org/10.1080/15548627.2026.2694658

Autophagy. 2026 Jun 21. 1-3

Mitophagy mitigates tau acetylation via the ULK1-NAD+/SIRT1 axis in Alzheimer's disease.

Jun-Ping Pan, Jianying Zhang, Ping-Jie Wang, Guobing Chen, Evandro Fei Fang.

Autophagy preserves neuronal integrity by clearing damaged proteins and other subcellular components, yet it declines with age and exacerbates in Alzheimer's disease (AD). Although autophagy reduces tauopathy, whether it can proactively restrict early tau pathology via post-translational modifications (PTMs) has remained unclear. In a recent paper, we have identified a mitophagy-based metabolic signaling mechanism linking the autophagy-initiating kinase Unc-51-like autophagy activating kinase 1 (ULK1) to the inhibition of pathogenic tau acetylation via the ULK1-NAD+/SIRT1 axis. Analyses of human biofluidic to postmortem and transcriptomic data reveal an age-associated decline of ULK1; this situation gets worse in AD with the extent of ULK1 reduction positively correlates with Tau-based Braak stage progression, consistent with a bidirectional vicious cycle in which pathological tau disrupts mitochondrial homeostasis and impairs autophagy. Restoring ULK1-dependent mitophagy breaks this cycle in the upstream: in the hTau.P301S mice, ULK1 overexpression reduces ac‑tauK174 leading to reduced tau pathology and improved cognition. Mechanistically, ULK1 activates PINK1- and FUNDC1- as well as AMBRA1-dependent mitophagy to eliminate damaged mitochondria, restore bioenergetics, and elevate intracellular NAD+, which activates the deacetylase SIRT1 to directly deacetylate tau at Lys174. Pharmacological ULK1 activation with a small molecule Rac‑BL‑918 phenocopies these protective effects in a mitophagy- and SIRT1-dependent manner. Collectively, our recent findings position mitophagy as a metabolic signaling hub that couples mitochondrial turnover to NAD+/SIRT1 activity to shape neuronal tau PTMs, supporting ULK1-mitophagy activation as an upstream strategy to limit tauopathy before overt aggregation.

Keywords: Ac‑tauK174; Mitophagy; NAD+; SIRT1; ULK1

DOI: https://doi.org/10.1080/15548627.2026.2689031

Mol Neurodegener Adv. 2026 ;2(1): 31

miRNA family miR-29 inhibits PINK1-PRKN signaling via ATG9A.

Briana N Markham, Chloe Ramnarine, Songeun Kim, William E Grever, Alexandra I Soto-Beasley, Michael G Heckman, Yingxue Ren, Andrew C Osborne, Mohammed Kehili, Aditya V Bhagwate, Yuanhang Liu, Chen Wang, Jungsu Kim, Zbigniew K Wszolek, Owen A Ross, Wolfdieter Springer, Fabienne C Fiesel.

Loss-of-function mutations in the genes encoding PINK1 and PRKN result in early-onset Parkinson disease (EOPD). Together, the encoded enzymes direct a neuroprotective pathway that ensures the elimination of damaged mitochondria via autophagy. We performed a genome-wide high-content imaging miRNA screen for inhibitors of the PINK1-PRKN pathway and identified all three members of the miRNA family 29 (miR-29). RNA sequencing revealed target genes regulated by miR-29 and identified ATG9A as a candidate gene. SiRNA-mediated ATG9A silencing phenocopied the effects of miR-29 and suppressed the initiation of PINK1-PRKN-mediated mitophagy. In addition, expression of ATG9A was able to rescue the effects of miR-29a, suggesting that ATG9A is primarily responsible for the inhibitory effect of miR-29. In an EOPD patient cohort, we further discovered two rare, potentially deleterious, ATG9A missense variants (p.R631W and p.S828L) and tested them experimentally in cells. Strikingly, neither EOPD ATG9A variant was able to rescue the phenotype suggesting they both act as loss-of-function mutations and might contribute to the etiology of disease. Together, our study validates miR-29 and its target gene ATG9A as novel regulators of PINK1-PRKN signaling. It further serves as proof-of-concept with the identification of novel, potentially disease-relevant EOPD variants specifically in mitophagy-regulating genes. The nomination of biological pathways is important for the stratification and treatment of patients that suffer from devastating diseases, such as EOPD.
Supplementary Information: The online version contains supplementary material available at 10.1186/s44477-026-00029-w.

Keywords: ATG9A; Hsa-miR-29; Mitophagy; PINK1; PRKN; Parkin; Parkinson’s disease

DOI: https://doi.org/10.1186/s44477-026-00029-w

Oncogene. 2026 Jun 20.

Hypoxia-induced MIC19 myristoylation promotes PRKN-dependent VDAC2 ubiquitination and activates mitophagy in non-small cell lung cancer.

Hua Huang, Chen Ding, Zexia Zhao, Wenhao Zhao, Guorui He, Hongbing Zhang, Peijie Chen, Yongwen Li, Hongyu Liu, Jun Chen.

Tumor hypoxia drives mitophagy reprogramming to support mitochondrial quality control in non-small cell lung cancer (NSCLC) cells, yet the role of the mitochondrial cristae organizers remains poorly understood. Here, we identified MIC19, a key subunit of mitochondrial contact site and cristae organizing system complex, as an essential regulator of hypoxia-induced mitophagy in NSCLC. We demonstrate that prolonged hypoxia induces MIC19 protein expression in a HIF-1α-dependent manner and that elevated MIC19 promotes NSCLC cell proliferation and metastasis. MIC19 sustains mitochondrial morphology and mitophagy activation under hypoxic stress. Mechanistically, HIF-1α transcriptionally upregulates NMT1, an N-myristoyltransferase that catalyzes N-myristoylation at Gly2 of MIC19 protein, which is essential for the mitochondrial localization and protein stability of MIC19. MIC19 facilitates PRKN-dependent K48-linked ubiquitination of the outer mitochondrial membrane protein voltage-dependent anion channel 2 (VDAC2), thereby promoting mitophagy progression under hypoxic stress. Therapeutically, suppression of MIC19 via shRNA combined with pharmacological inhibition of autophagy using chloroquine synergistically impairs NSCLC tumor growth in vivo. Collectively, these findings uncover a previously unrecognized HIF-1α-NMT1-MIC19-VDAC2 axis that drives hypoxia-adaptive mitophagy and reveals a potential therapeutic vulnerability in hypoxic NSCLC.

DOI: https://doi.org/10.1038/s41388-026-03847-0

iScience. 2026 Jul 17. 29(7): 116345

BCAS-3 is required for the progression of autophagosome formation to degrade paternal mitochondria in Caenorhabditis elegans.

Takuya Norizuki, Taeko Sasaki, Yuji Suehiro, Shohei Mitani, Waka Kojima, Koji Yamano, Noriyuki Matsuda, Miyuki Sato.

In the nematode Caenorhabditis elegans, autophagy degrades paternal mitochondria after fertilization to ensure the maternal inheritance of mitochondrial DNA. We previously showed that the autophagy adaptor ALLO-1 is first targeted to paternal mitochondria and then recruits the autophagy machinery. However, the mechanisms underlying local autophagosome formation remain unclear. Here, our forward genetic screen identified a WD40 repeat domain-containing protein, BCAS-3, and its interactor, PHAF-1, as essential factors for paternal mitochondrial degradation. After fertilization, BCAS-3 and PHAF-1 are recruited to the paternal mitochondria, and the loss of these genes impairs the progression of autophagosome formation. We further show that BCAS-3 recruitment is regulated downstream of the WD40 repeat domain-containing core autophagy proteins, ATG-18 and EPG-6, but BCAS-3 also contributes to further ATG-18 accumulation around paternal mitochondria. These findings suggest that the interplay between BCAS-3 and ATG-18 underlies the progression of autophagosome formation during paternal mitochondrial degradation.

Keywords: cell biology; developmental biology; molecular biology

DOI: https://doi.org/10.1016/j.isci.2026.116345

NPJ Parkinsons Dis. 2026 Jun 24.

Loss of PINK1 causes age-dependent mitochondrial trafficking deficits in nigrostriatal dopaminergic neurons via aberrant p38 MAPK activation.

Jingyu Zhao, Yuanxin Chen, Lianteng Zhi, Qing Xu, Juan Subiry, Zebang Chen, Shiquan Cui, Hui Zhang, Chenjian Li.

Mutations in PTEN-induced putative kinase 1 (PINK1) cause early-onset, autosomal-recessive Parkinson's disease (PD). While previous studies have shown age-related declines in dopamine release and ATP levels in Pink1-/- mice, the mechanisms remain unclear. Using a novel TH-Mito-Dendra2 transgenic mouse model to label dopaminergic neuron mitochondria, we show that PINK1 loss leads to age-dependent defects in axonal mitochondrial trafficking in acute brain slices. These deficits are characterized by reduced anterograde transport and increased mitochondrial stalling. Pharmacological induction of reactive oxygen species (ROS) and calcium release impaired mitochondrial mobility. Consistent with this, Pink1 knockout mice exhibited elevated mitochondrial calcium, oxidation levels, and p38 MAPK hyperactivation. Treatment with a calcium channel blocker and p38 inhibitor SB202190 restored mitochondrial motility and increased anterograde transport. Together, our findings suggest that PINK1 loss disrupts mitochondrial trafficking by disturbing calcium and redox homeostasis via the p38 pathway, contributing to PD pathogenesis.

DOI: https://doi.org/10.1038/s41531-026-01443-3

Autophagy. 2026 Jun 21.

EGR1 mediates neuronal damage via suppressing HIF1A-induced mitophagy following traumatic brain injury.

Xiaoxiang Hou, Danfeng Zhang, Xianzheng Sang, Chaogui Peng, Wen Chen, Jing Xu, Yichao Ye, Yangu Guo, Hantong Shi, Chengzi Yang, Hanzi Cai, Yijian Wang, Guangxin Chu, Haoxiang Xu, Liquan Lv, Hai Jin, Chunhui Wang, Xiaolin Qu.

Traumatic brain injury (TBI) remains a leading cause of neurological morbidity and mortality, characterized by complex pathophysiological cascades. Here, we investigate the role of the transcription factor EGR1 (early growth response 1) in modulating mitochondrial homeostasis via the HIF1A (hypoxia inducible factor 1, alpha subunit)-BNIP3 (BCL2/adenovirus E1B interacting protein 3) axis following TBI. Using integrated transcriptomic and epigenomic analyses, we identified EGR1 as a critical regulator of TBI pathology, with its expression acutely upregulated in neurons post-injury. Genetic ablation of Egr1 in mice significantly reduced neuronal apoptosis, preserved dendritic integrity, and ameliorated cognitive and sensorimotor deficits. Mechanistically, chromatin immunoprecipitation and luciferase assays revealed that EGR1 directly binds to the Hif1a promoter, repressing its transcription. Loss of EGR1 enhanced HIF1A-BNIP3-mediated mitophagy, reducing mitochondrial dysfunction and oxidative stress both in vitro and in vivo. Conversely, silencing HIF1A or BNIP3 abrogated the neuroprotective effects of EGR1 deficiency. These findings establish a novel EGR1-HIF1A-mitophagy signaling axis as a key determinant of TBI outcomes, highlighting EGR1 as a potential therapeutic target. Abbreviations: AAV: adeno-associated virus; ACTB/β-actin: actin, beta; AIF1/IBA1: allograft inflammatory factor 1; BAF: bafilomycin A1; BNIP3: BCL2/adenovirus E1B interacting protein 3; CCI: controlled cortical impact; COX8: cytochrome c oxidase subunit 8; CUT&Tag: cleavage under targets and tagmentation; DAPI: 4,'6-diamidino-2-phenylindole; DEGs: differentially expressed genes; eGFP: enhanced green fluorescent protein; EGR1: early growth response 1; GFAP: glial fibrillary acidic protein; GO: gene ontology; GSEA: gene set enrichment analysis; HCQ: hydroxychloroquine; HIF1A/HIF-1α: hypoxia inducible factor 1, alpha subunit; IGV: integrative genomics viewer; KEGG: Kyoto encyclopedia of genes and genomes; KO: knockout; LAMP1: lysosomal-associated membrane protein 1; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; Lv: lentivirus; MAP2: microtubule-associated protein 2; mCherry: monomeric cherry fluorescent protein; mRFP: monomeric red fluorescent protein; MTOR: mechanistic target of rapamycin kinase; MUT: mutant; MWM: Morris water maze; NAB1: Ngfi-A binding protein 1; NAB2: Ngfi-A binding protein 2; RBFOX3/NeuN: RNA binding protein, fox-1 homolog (C. elegans) 3; OGD: oxygen-glucose deprivation; OLIG2: oligodendrocyte transcription factor 2; PBS: phosphate-buffered saline; PECAM1/CD31: platelet/endothelial cell adhesion molecule 1; PFA: paraformaldehyde; PPI: protein-protein interaction; Puro: puromycin; ROI: region of interest; ROS: reactive oxygen species; SEM: standard error of the mean; SQSTM1/p62: sequestosome 1; TBI: traumatic brain injury; TOMM20: translocase of outer mitochondrial membrane 20; TSA: tyramide signal amplification; TUNEL: terminal deoxynucleotidyl transferase dUTP nick end labeling; VDAC1: voltage-dependent anion channel 1; WT: wild-type.

Keywords: EGR1; HIF1A; mitophagy; neuron; traumatic brain injury

DOI: https://doi.org/10.1080/15548627.2026.2693261