bims-nenemi 2024-09-22 papers

bims-nenemi

Biomed News

on Neuroinflammation, neurodegeneration and mitochondria

Issue of 2024–09–22
thirteen papers selected by
Marco Tigano, Thomas Jefferson University

Overactive mitochondrial DNA replication disrupts perinatal cardiac maturation.
Microglial mitochondrial DNA release contributes to neuroinflammation after intracerebral hemorrhage through activating AIM2 inflammasome.
Multiple distinct evolutionary mechanisms govern the dynamics of selfish mitochondrial genomes in Caenorhabditis elegans.
Quantitative proteomics of patient fibroblasts reveal biomarkers and diagnostic signatures of mitochondrial disease.
A shorter splicing isoform antagonizes ZBP1 to modulate cell death and inflammatory responses.
Alternative splicing of Mff regulates AMPK-mediated phosphorylation, mitochondrial fission and antiviral response.
The long non-coding RNA ROSALIND protects the mitochondrial translational machinery from oxidative damage.
Mitophagy deficiency activates stimulator of interferon genes activation and aggravates pathogenetic cardiac remodeling.
Biallelic PTPMT1 variants disrupt cardiolipin metabolism and lead to a neurodevelopmental syndrome.
Krebs cycle derivatives, dimethyl fumarate and itaconate, control metabolic reprogramming in inflammatory human microglia cell line.
CRISPRi with barcoded expression reporters dissects regulatory networks in human cells.
VPS13D affects epileptic seizures by regulating mitochondrial fission and autophagy in epileptic rats.
TBK1 adaptor AZI2/NAP1 regulates NDP52-driven mitochondrial autophagy.

Nat Commun. 2024 Sep 14. 15(1): 8066

Overactive mitochondrial DNA replication disrupts perinatal cardiac maturation.

Juan C Landoni, Semin Erkul, Tuomas Laalo, Steffi Goffart, Riikka Kivelä, Karlo Skube, Anni I Nieminen, Sara A Wickström, James Stewart, Anu Suomalainen.

High mitochondrial DNA (mtDNA) amount has been reported to be beneficial for resistance and recovery of metabolic stress, while increased mtDNA synthesis activity can drive aging signs. The intriguing contrast of these two mtDNA boosting outcomes prompted us to jointly elevate mtDNA amount and frequency of replication in mice. We report that high activity of mtDNA synthesis inhibits perinatal metabolic maturation of the heart. The offspring of the asymptomatic parental lines are born healthy but manifest dilated cardiomyopathy and cardiac collapse during the first days of life. The pathogenesis, further enhanced by mtDNA mutagenesis, involves prenatal upregulation of mitochondrial integrated stress response and the ferroptosis-inducer MESH1, leading to cardiac fibrosis and cardiomyocyte death after birth. Our evidence indicates that the tight control of mtDNA replication is critical for early cardiac homeostasis. Importantly, ferroptosis sensitivity is a potential targetable mechanism for infantile-onset cardiomyopathy, a common manifestation of mitochondrial diseases.

DOI: https://doi.org/10.1038/s41467-024-52164-1
Exp Neurol. 2024 Sep 13. pii: S0014-4886(24)00276-0. [Epub ahead of print]382 114950

Microglial mitochondrial DNA release contributes to neuroinflammation after intracerebral hemorrhage through activating AIM2 inflammasome.

Feng Gu, Zongqi Wang, Haojie Ding, Xinyu Tao, Juyi Zhang, Kun Dai, Xiang Li, Haitao Shen, Haiying Li, Zhouqing Chen, Zhong Wang.

  Intracerebral hemorrhage (ICH) is a severe disease that often leads to disability and death. Neuroinflammatory response is a key causative factor of early secondary brain injury after ICH. AIM2 is a DNA-sensing protein that recognizes cytosolic double-stranded DNA and take a significant part in neuroinflammation. Mitochondrial DNA participates in the translation of proteins such as the respiratory chain in the mitochondria. Whether mtDNA is involved in forming AIM2 inflammasome after ICH remains unclear. We used mice to construct ICH model in vivo and we used BV2 microglial cells treated with oxyhemoglobin to simulate ICH in vitro. Following lentiviral transfection to overexpress AIM2 antagonist P202, a notable decrease was observed in the levels of AIM2 inflammasome-associated proteins, leading to a reduction in dead neurons surrounding the hematoma and an enhancement in long-term and short-term behavior of neurological deficits. We further explored whether mtDNA took part in the AIM2 activation after ICH. The cytosolic mtDNA level was down-regulated by the mitochondrial division protector Mdivi-1 and up-regulated by transfection of mtDNA into cytoplasm. We found the expression level of AIM2 inflammasome-related proteins and inflammatory cytokines release were regulated by the cytosolic mtDNA level. In conclusion, after ICH, the mtDNA content in the cytoplasm of microglia around the hematoma rises, causing AIM2 inflammation leading to neuronal apoptosis, which leads to neurological deficits in mice. On the other hand, P202 was able to block inflammatory vesicle activation and improve neurological function by preventing the interaction between AIM2 protein and mitochondrial DNA.

Keywords:  Inflammasome; Intracerebral hemorrhage; Mitochondrial DNA; Neuroinflammation; Secondary brain injury

DOI:  https://doi.org/10.1016/j.expneurol.2024.114950
Nat Commun. 2024 Sep 19. 15(1): 8237

Multiple distinct evolutionary mechanisms govern the dynamics of selfish mitochondrial genomes in Caenorhabditis elegans.

Bryan L Gitschlag, Claudia V Pereira, James P Held, David M McCandlish, Maulik R Patel.

Cells possess multiple mitochondrial DNA (mtDNA) copies, which undergo semi-autonomous replication and stochastic inheritance. This enables mutant mtDNA variants to arise and selfishly compete with cooperative (wildtype) mtDNA. Selfish mitochondrial genomes are subject to selection at different levels: they compete against wildtype mtDNA directly within hosts and indirectly through organism-level selection. However, determining the relative contributions of selection at different levels has proven challenging. We overcome this challenge by combining mathematical modeling with experiments designed to isolate the levels of selection. Applying this approach to many selfish mitochondrial genotypes in Caenorhabditis elegans reveals an unexpected diversity of evolutionary mechanisms. Some mutant genomes persist at high frequency for many generations, despite a host fitness cost, by aggressively outcompeting cooperative genomes within hosts. Conversely, some mutant genomes persist by evading inter-organismal selection. Strikingly, the mutant genomes vary dramatically in their susceptibility to genetic drift. Although different mechanisms can cause high frequency of selfish mtDNA, we show how they give rise to characteristically different distributions of mutant frequency among individuals. Given that heteroplasmic frequency represents a key determinant of phenotypic severity, this work outlines an evolutionary theoretic framework for predicting the distribution of phenotypic consequences among individuals carrying a selfish mitochondrial genome.

DOI: https://doi.org/10.1038/s41467-024-52596-9
JCI Insight. 2024 Sep 17. pii: e178645. [Epub ahead of print]

Quantitative proteomics of patient fibroblasts reveal biomarkers and diagnostic signatures of mitochondrial disease.

Sandrina P Correia, Marco F Moedas, Lucie S Taylor, Karin Naess, Albert Z Lim, Robert McFarland, Zuzanna Kazior, Anastasia Rumyantseva, Rolf Wibom, Martin Engvall, Helene Bruhn, Nicole Lesko, Ákos Végvári, Lukas Käll, Matthias Trost, Charlotte L Alston, Christoph Freyer, Robert W Taylor, Anna Wedell, Anna Wredenberg.

   BACKGROUND: Mitochondrial diseases belong to the group of inborn errors of metabolism (IEM), with a prevalence of 1:2,000-1:5,000. They are the most common form of IEM, but despite advances in next-generation sequencing technologies, almost half of the patients are left genetically undiagnosed.
METHODS: We investigated a cohort of 61 patients with defined mitochondrial disease to improve diagnostics, identify biomarkers, and correlate metabolic pathways to specific disease groups. Clinical presentations were structured using human phenotype ontology terms, and mass spectrometry-based proteomics was performed on primary fibroblasts. Additionally, we integrated six patients carrying variants of uncertain significance (VUS) to test proteomics as a diagnostic expansion.
RESULTS: Proteomic profiles from patient samples could be classified according to their biochemical and genetic characteristics, with the expression of five proteins (GPX4, MORF4L1, MOXD1, MSRA and TMED9) correlating with the disease cohort, and thus, acting as putative biomarkers. Pathway analysis showed a deregulation of inflammatory and mitochondrial stress responses. This included the upregulation of glycosphingolipid metabolism and mitochondrial protein import, as well as the downregulation of arachidonic acid metabolism. Furthermore, we could assign pathogenicity to a VUS in MRPS23 by demonstrating the loss of associated mitochondrial ribosome subunits.
CONCLUSION: We established mass spectrometry-based proteomics on patient fibroblasts as a viable and versatile tool for diagnosing patients with mitochondrial disease.
FUNDING: The NovoNordisk Foundation, Knut and Alice Wallenberg Foundation, Wellcome Centre for Mitochondrial Research, UK Medical Research Council, and the UK NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children.

Keywords:  Metabolism; Mitochondria; Molecular diagnosis; Proteomics

DOI:  https://doi.org/10.1172/jci.insight.178645
EMBO J. 2024 Sep 19.

A shorter splicing isoform antagonizes ZBP1 to modulate cell death and inflammatory responses.

Masahiro Nagata, Yasmin Carvalho Schäfer, Laurens Wachsmuth, Manolis Pasparakis.

  Z-DNA-binding protein 1 (ZBP1) is an interferon-inducible sensor of Z-DNA and Z-RNA, which has emerged as a critical regulator of cell death and inflammation. ZBP1 binds Z-DNA and Z-RNA via its Zα domains, and signals by engaging RIPK3 and RIPK1 via its RIP homotypic interaction motifs (RHIMs). Here, we show that mice express an alternatively-spliced shorter ZBP1 isoform (ZBP1-S), which harbours the Zα domains but lacks the RHIMs, and acts as an endogenous inhibitor of the full-length protein (ZBP1-L). Mice and cells expressing only ZBP1-S are resistant to ZBP1-mediated cell death and inflammation. In contrast, cells lacking ZBP1-S show increased ZBP1-L-induced death compared to cells expressing both isoforms. Moreover, loss of the short isoform accelerates and exacerbates skin inflammation induced by ZBP1-mediated necroptosis of RIPK1-deficient keratinocytes, revealing an important physiological role of ZBP1-S. Mechanistically, ZBP1-S suppresses ZBP1-L-mediated cell death by binding to Z-nucleic acids via its Zα domains. Therefore, ZBP1-S acts as an endogenous inhibitor that competes with full-length ZBP1-L for binding Z-nucleic acid ligands to fine-tune ZBP1-mediated cell death and inflammation.

Keywords:  Cell Death; Inflammation; Necroptosis; ZBP1

DOI:  https://doi.org/10.1038/s44318-024-00238-7
Pharmacol Res. 2024 Sep 16. pii: S1043-6618(24)00359-1. [Epub ahead of print] 107414

Alternative splicing of Mff regulates AMPK-mediated phosphorylation, mitochondrial fission and antiviral response.

Yuki Hanada, Risa Maeda, Takaya Ishihara, Masaki Nakahashi, Yuichi Matsushima, Emi Ogasawara, Toshihiko Oka, Naotada Ishihara.

  Mitochondrial morphology and function change dynamically in response to intracellular signaling and the surrounding environment. The mitochondrial fission factor Mff, which localizes to the outer mitochondrial membrane, mediates not only mitochondrial fission by recruiting the dynamin-related GTPase Drp1 to mitochondrial fission sites but also the double-stranded RNA-induced antiviral response on mitochondria through mitochondrial antiviral signaling (MAVS). Mff is reported to be regulated by AMP-activated protein kinase (AMPK)-mediated protein phosphorylation and alternative pre-mRNA splicing; however, the relationships among RNA splicing, phosphorylation, and multiple functions of Mff have not been fully understood. Here, we showed that mouse Mff has a tissue-specific splicing pattern, and at least eight Mff splice isoforms were expressed in mouse embryonic fibroblasts (MEFs). We introduced single Mff isoforms into Mff knockout MEFs and found that insertion of exon 6 just after the phosphorylation site, by the alternative splicing, reduced its phosphorylation by AMPK and its functions in mitochondrial fission and the antiviral response. In addition, the underlying mechanism repressing these functions was independent of phosphorylation. These results indicate that multiple functions of Mff on mitochondria are regulated by AMPK-mediated phosphorylation and alternative splicing, under the control of energy metabolism and cellular differentiation.

Keywords:  Alternative splicing; Antiviral innate immune response; Energy, metabolism; Mitochondrial fission; mitochondria

DOI:  https://doi.org/10.1016/j.phrs.2024.107414
Cell Death Differ. 2024 Sep 18.

The long non-coding RNA ROSALIND protects the mitochondrial translational machinery from oxidative damage.

Vicky Katopodi, Alessandro Marino, Nikoleta Pateraki, Yvessa Verheyden, Sonia Cinque, Elena Lara Jimenez, Sara Adnane, Ewout Demesmaeker, Alice Scomparin, Rita Derua, Elisabetta Groaz, Eleonora Leucci.

Upregulation of mitochondrial respiration coupled with high ROS-scavenging capacity is a characteristic shared by drug-tolerant cells in several cancers. As translational fidelity is essential for cell fitness, protection of the mitochondrial and cytosolic ribosomes from oxidative damage is pivotal. While mechanisms for recognising and repairing such damage exist in the cytoplasm, the corresponding process in the mitochondria remains unclear.By performing Ascorbate PEroXidase (APEX)-proximity ligation assay directed to the mitochondrial matrix followed by isolation and sequencing of RNA associated to mitochondrial proteins, we identified the nuclear-encoded lncRNA ROSALIND as an interacting partner of ribosomes. ROSALIND is upregulated in recurrent tumours and its expression can discriminate between responders and non-responders to immune checkpoint blockade in a melanoma cohort of patients. Featuring an unusually high G content, ROSALIND serves as a substrate for oxidation. Consequently, inhibiting ROSALIND leads to an increase in ROS and protein oxidation, resulting in severe mitochondrial respiration defects. This, in turn, impairs melanoma cell viability and increases immunogenicity both in vitro and ex vivo in preclinical humanised cancer models. These findings underscore the role of ROSALIND as a novel ROS buffering system, safeguarding mitochondrial translation from oxidative stress, and shed light on potential therapeutic strategies for overcoming cancer therapy resistance.

DOI: https://doi.org/10.1038/s41418-024-01377-4
Genes Dis. 2024 Nov;11(6): 101074

Mitophagy deficiency activates stimulator of interferon genes activation and aggravates pathogenetic cardiac remodeling.

Guoxiang Zhou, Xiaowen Wang, Mingyu Guo, Can Qu, Lei Gao, Jiang Yu, Yuanjing Li, Suxin Luo, Qiong Shi, Yongzheng Guo.

  Stimulator of interferon genes (STING) has recently been found to play a crucial role in cardiac sterile inflammation and dysfunction. The role of stimulator of interferon genes (STING) in cardiac sterile inflammation and dysfunction has been recently discovered. This study aims to examine the involvement of STING in pathological cardiac remodeling and the mechanisms that govern the activation of the STING pathway. To investigate this, transverse aortic constriction (TAC) was performed on STING knockout mice to induce pressure overload-induced cardiac remodeling. Subsequently, cardiac function, remodeling, and inflammation levels were evaluated. The STING pathway was found to be activated in the pressure overload-stressed heart and angiotensin II (Ang II)-stimulated cardiac fibroblasts. Loss of STING expression led to a significant reduction in inflammatory responses, mitochondrial fragmentation, and oxidative stress in the heart, resulting in attenuated cardiac remodeling and dysfunction. Furthermore, the exacerbation of pressure overload-induced STING-mediated inflammation and pathological cardiac remodeling was observed when mitophagy was suppressed through the silencing of Parkin, an E3 ubiquitin ligase. Taken together, these findings indicate that STING represents a newly identified and significant molecule implicated in the process of pathological cardiac remodeling and that mitophagy is an upstream mechanism that regulates STING activation. Targeting STING may therefore provide a novel therapeutic strategy for pathological cardiac remodeling and heart failure.

Keywords:  Cardiac remodeling; Mitochondrial autophagy; STING; Sterile inflammation; mtDNA

DOI:  https://doi.org/10.1016/j.gendis.2023.08.003
Brain. 2024 Aug 30. pii: awae268. [Epub ahead of print]

Biallelic PTPMT1 variants disrupt cardiolipin metabolism and lead to a neurodevelopmental syndrome.

Micol Falabella, Chiara Pizzamiglio, Luis Carlos Tabara, Benjamin Munro, Mohamed S Abdel-Hamid, Ece Sonmezler, William L Macken, Shanti Lu, Lisa Tilokani, Padraig J Flannery, Nina Patel, Simon A S Pope, Simon J R Heales, Dania B H Hammadi, Charlotte L Alston, Robert W Taylor, Hanns Lochmuller, Cathy E Woodward, Robyn Labrum, Jana Vandrovcova, Henry Houlden, Efstathia Chronopoulou, Germaine Pierre, Reza Maroofian, Michael G Hanna, Jan-Willem Taanman, Semra Hiz, Yavuz Oktay, Maha S Zaki, Rita Horvath, Julien Prudent, Robert D S Pitceathly.

  Primary mitochondrial diseases (PMDs) are among the most common inherited neurological disorders. They are caused by pathogenic variants in mitochondrial or nuclear DNA that disrupt mitochondrial structure and/or function, leading to impaired oxidative phosphorylation (OXPHOS). One emerging subcategory of PMDs involves defective phospholipid (PL) metabolism. Cardiolipin (CL), the signature PL of mitochondria, resides primarily in the inner mitochondrial membrane, where it is biosynthesised and remodelled via multiple enzymes and is fundamental to several aspects of mitochondrial biology. Genes that contribute to CL biosynthesis have recently been linked with PMD. However, the pathophysiological mechanisms that underpin human CL-related PMDs are not fully characterised. Here, we report six individuals, from three independent families, harbouring biallelic variants in PTPMT1, a mitochondrial tyrosine phosphatase required for de novo CL biosynthesis. All patients presented with a complex, neonatal/infantile onset neurological and neurodevelopmental syndrome comprising developmental delay, microcephaly, facial dysmorphism, epilepsy, spasticity, cerebellar ataxia and nystagmus, sensorineural hearing loss, optic atrophy, and bulbar dysfunction. Brain MRI revealed a variable combination of corpus callosum thinning, cerebellar atrophy, and white matter changes. Using patient-derived fibroblasts and skeletal muscle tissue, combined with cellular rescue experiments, we characterise the molecular defects associated with mutant PTPMT1 and confirm the downstream pathogenic effects that loss of PTPMT1 has on mitochondrial structure and function. To further characterise the functional role of PTPMT1 in CL homeostasis, we established a zebrafish ptpmt1 knockout model associated with abnormalities in body size, developmental alterations, decreased total CL levels, and OXPHOS deficiency. Together, these data indicate that loss of PTPMT1 function is associated with a new autosomal recessive PMD caused by impaired CL metabolism, highlight the contribution of aberrant CL metabolism towards human disease, and emphasise the importance of normal CL homeostasis during neurodevelopment.

Keywords:  cardiolipin; mitochondria; mitochondrial dynamics; neurodevelopmental syndrome; primary mitochondrial disease

DOI:  https://doi.org/10.1093/brain/awae268
Mitochondrion. 2024 Sep 12. pii: S1567-7249(24)00124-7. [Epub ahead of print] 101966

Krebs cycle derivatives, dimethyl fumarate and itaconate, control metabolic reprogramming in inflammatory human microglia cell line.

Moris Sangineto, Martina Ciarnelli, Archana Moola, Vidyasagar Naik Bukke, Tommaso Cassano, Rosanna Villani, Antonino D Romano, Giuseppe Di Gioia, Carlo Avolio, Gaetano Serviddio.

  Metabolic reprogramming drives inflammatory activity in macrophages, including microglia, with Krebs cycle (KC) intermediates playing a crucial role as signaling molecules. Here, we show that the bioenergetic profile of LPS-activated human microglialclone 3 cell line (HMC3) is characterized by high levels of glycolysis and mitochondrial (mt) respiration, and the treatment with KC derivatives, namely dimethyl-fumarate (DMF) and itaconate (ITA), almost restores normal metabolism. However, despite comparable bioenergetic and anti-inflammatory effects, the mt hyper-activity was differentially modulated by DMF and ITA. DMF normalized complex I activity, while ITA dampened both complex I and II hyper-activity counteracting oxidative stress more efficiently.

Keywords:  Dimethyl fumarate; Immunometabolism; Itaconate; Krebs cycle; Microglia; Mitochondria

DOI:  https://doi.org/10.1016/j.mito.2024.101966
bioRxiv. 2024 Sep 06. pii: 2024.09.06.611573. [Epub ahead of print]

CRISPRi with barcoded expression reporters dissects regulatory networks in human cells.

Jinyoung Kim, Ryan Y Muller, Eliana R Bondra, Nicholas T Ingolia.

Genome-wide CRISPR screens have emerged as powerful tools for uncovering the genetic underpinnings of diverse biological processes. Incisive screens often depend on directly measuring molecular phenotypes, such as regulated gene expression changes, provoked by CRISPR-mediated genetic perturbations. Here, we provide quantitative measurements of transcriptional responses in human cells across genome-scale perturbation libraries by coupling CRISPR interference (CRISPRi) with barcoded expression reporter sequencing (CiBER-seq). To enable CiBER-seq in mammalian cells, we optimize the integration of highly complex, barcoded sgRNA libraries into a defined genomic context. CiBER-seq profiling of a nuclear factor kappa B (NF-κB) reporter delineates the canonical signaling cascade linking the transmembrane TNF-alpha receptor to inflammatory gene activation and highlights cell-type-specific factors in this response. Importantly, CiBER-seq relies solely on bulk RNA sequencing to capture the regulatory circuit driving this rapid transcriptional response. Our work demonstrates the accuracy of CiBER-seq and its potential for dissecting genetic networks in mammalian cells with superior time resolution.

DOI: https://doi.org/10.1101/2024.09.06.611573
Genes Dis. 2024 Nov;11(6): 101266

VPS13D affects epileptic seizures by regulating mitochondrial fission and autophagy in epileptic rats.

Jian Wang, Fan Zhang, Zhong Luo, Haiqing Zhang, Changyin Yu, Zucai Xu.

  Abnormal mitochondrial dynamics can lead to seizures, and improved mitochondrial dynamics can alleviate seizures. Vacuolar protein sorting 13D (VPS13D) is closely associated with regulating mitochondrial homeostasis and autophagy. However, further investigation is required to determine whether VPS13D affects seizures by influencing mitochondrial dynamics and autophagy. We aimed to investigate the influence of VPS13D on behavior in a rat model of acute epileptic seizures. Hence, we established an acute epileptic seizure rat model and employed the CRISPR/CAS9 technology to construct a lentivirus to silence the Vps13d gene. Furthermore, we used the HT22 mouse hippocampal neuron cell line to establish a stable strain with suppressed expression of Vps13d in vitro. Then, we performed quantitative proteomic and bioinformatics analyses to confirm the mechanism by which VPS13D influences mitochondrial dynamics and autophagy, both in vitro and in vivo using the experimental acute epileptic seizure model. We found that knockdown of Vps13d resulted in reduced seizure latency and increased seizure frequency in the experimental rats. Immunofluorescence staining and western blot analysis revealed a significant increase in mitochondrial dynamin-related protein 1 expression following Vps13d knockdown. Moreover, we observed a significant reduction in LC3II protein expression levels and the LC3II/LC3I ratio (indicators for autophagy) accompanied by a significant increase in P62 expression (an autophagy adaptor protein). The proteomic analysis confirmed the up-regulation of P62 protein expression. Therefore, we propose that VPS13D plays a role in modulating seizures by influencing mitochondrial dynamics and autophagy.

Keywords:  Autophagy; Mitochondrial dynamics; Mitochondrial fission; Seizures; VPS13D

DOI:  https://doi.org/10.1016/j.gendis.2024.101266
J Biol Chem. 2024 Sep 12. pii: S0021-9258(24)02276-2. [Epub ahead of print] 107775

TBK1 adaptor AZI2/NAP1 regulates NDP52-driven mitochondrial autophagy.

Ryu Endo, Hiroki Kinefuchi, Momoha Sawada, Reika Kikuchi, Waka Kojima, Noriyuki Matsuda, Koji Yamano.

  Damaged mitochondria are selectively eliminated in a process called mitophagy. PINK1 and Parkin amplify ubiquitin signals on damaged mitochondria, which are then recognized by autophagy adaptors to induce local autophagosome formation. NDP52 and OPTN, two essential mitophagy adaptors, facilitate de novo synthesis of pre-autophagosomal membranes near damaged mitochondria by linking ubiquitinated mitochondria and ATG8 family proteins and by recruiting core autophagy initiation components. The multifunctional serine/threonine kinase TBK1 also plays important roles in mitophagy. OPTN directly binds TBK1 to form a positive feedback loop for isolation membrane expansion. TBK1 is also thought to indirectly interact with NDP52; however, its role in NDP52-driven mitophagy remains largely unknown. Here, we focused on two TBK1 adaptors, AZI2/NAP1 and TBKBP1/SINTBAD, that are thought to mediate the TBK1-NDP52 interaction. We found that both AZI2 and TBKBP1 are recruited to damaged mitochondria during Parkin-mediated mitophagy. Further, a series of AZI2 and TBKBP1 knockout constructs combined with an OPTN knockout showed that AZI2, but not TBKBP1, impacts NDP52-driven mitophagy. In addition, we found that AZI2 at S318 is phosphorylated during mitophagy, the impairment of which slightly inhibits mitochondrial degradation. These results suggest that AZI2, in concert with TBK1, plays an important role in NDP52-driven mitophagy.

Keywords:  autophagy; mitochondria; mitophagy; polyubiquitin chain; serine/threonine protein kinase

DOI:  https://doi.org/10.1016/j.jbc.2024.107775