bims-nenemi 2024-03-24 papers

bims-nenemi

Biomed News

on Neuroinflammation, neurodegeneration and mitochondria

Issue of 2024–03–24
eightteen papers selected by
Marco Tigano, Thomas Jefferson University

Endogenous BAX and BAK form mosaic rings of variable size and composition on apoptotic mitochondria.
A kinetic dichotomy between mitochondrial and nuclear gene expression processes.
Si-Wu-Tang attenuates hepatocyte PANoptosis and M1 polarization of macrophages in non-alcoholic fatty liver disease by influencing the intercellular transfer of mtDNA.
A peptide derived from TID1S rescues frataxin deficiency and mitochondrial defects in FRDA cellular models.
mtDNA regulates cGAS-STING signaling pathway in adenomyosis.
Local mitochondrial replication in the periphery of neurons requires the eEF1A1 protein and thetranslation of nuclear-encoded proteins.
A SIFI odyssey: Silencing the stress response amid mitochondrial import blockade to safeguard cell survival.
Cellular architecture of evolving neuroinflammatory lesions and multiple sclerosis pathology.
AMPK Suppression Due to Obesity Drives Oocyte mtDNA Heteroplasmy via ATF5-POLG Axis.
Mitochondrial transcription factor A (TFAM) has 5'-deoxyribose phosphate lyase activity in vitro.
MCU-independent Ca2+ uptake mediates mitochondrial Ca2+ overload and necrotic cell death in a mouse model of Duchenne muscular dystrophy.
Osteocyte mitochondria regulate angiogenesis of transcortical vessels.
Involvement of retinoic acid‑inducible gene‑I in radiation‑induced senescence of human umbilical vein endothelial cells.
Activation of STING signaling aggravates chronic alcohol exposure-induced cognitive impairment by increasing neuroinflammation and mitochondrial apoptosis.
ER stress promotes mitochondrial calcium overload and activates the ROS/NLRP3 axis to mediate fatty liver ischemic injury.
Mutant huntingtin protein induces MLH1 degradation, DNA hyperexcision, and cGAS-STING-dependent apoptosis.
Sensing of mitochondrial DNA by ZBP1 promotes RIPK3-mediated necroptosis and ferroptosis in response to diquat poisoning.
PLCE1 enhances mitochondrial dysfunction to promote GSDME-mediated pyroptosis in doxorubicin-induced cardiotoxicity.

Cell Death Differ. 2024 Mar 19.

Endogenous BAX and BAK form mosaic rings of variable size and composition on apoptotic mitochondria.

Sarah V Schweighofer, Daniel C Jans, Jan Keller-Findeisen, Anne Folmeg, Peter Ilgen, Mark Bates, Stefan Jakobs.

One hallmark of apoptosis is the oligomerization of BAX and BAK to form a pore in the mitochondrial outer membrane, which mediates the release of pro-apoptotic intermembrane space proteins into the cytosol. Cells overexpressing BAX or BAK fusion proteins are a powerful model system to study the dynamics and localization of these proteins in cells. However, it is unclear whether overexpressed BAX and BAK form the same ultrastructural assemblies following the same spatiotemporal hierarchy as endogenously expressed proteins. Combining live- and fixed-cell STED super-resolution microscopy, we show that overexpression of BAK results in novel BAK structures, which are virtually absent in non-overexpressing apoptotic cells. We further demonstrate that in wild type cells, BAK is recruited to apoptotic pores before BAX. Both proteins together form unordered, mosaic rings on apoptotic mitochondria in immortalized cell culture models as well as in human primary cells. In BAX- or BAK- single-knockout cells, the remaining protein is able to form rings independently. The heterogeneous nature of these rings in both wild type as well as single-knockout cells corroborates the toroidal apoptotic pore model.

DOI: https://doi.org/10.1038/s41418-024-01273-x
Mol Cell. 2024 Mar 14. pii: S1097-2765(24)00170-9. [Epub ahead of print]

A kinetic dichotomy between mitochondrial and nuclear gene expression processes.

Erik McShane, Mary Couvillion, Robert Ietswaart, Gyan Prakash, Brendan M Smalec, Iliana Soto, Autum R Baxter-Koenigs, Karine Choquet, L Stirling Churchman.

  Oxidative phosphorylation (OXPHOS) complexes, encoded by both mitochondrial and nuclear DNA, are essential producers of cellular ATP, but how nuclear and mitochondrial gene expression steps are coordinated to achieve balanced OXPHOS subunit biogenesis remains unresolved. Here, we present a parallel quantitative analysis of the human nuclear and mitochondrial messenger RNA (mt-mRNA) life cycles, including transcript production, processing, ribosome association, and degradation. The kinetic rates of nearly every stage of gene expression differed starkly across compartments. Compared with nuclear mRNAs, mt-mRNAs were produced 1,100-fold more, degraded 7-fold faster, and accumulated to 160-fold higher levels. Quantitative modeling and depletion of mitochondrial factors LRPPRC and FASTKD5 identified critical points of mitochondrial regulatory control, revealing that the mitonuclear expression disparities intrinsically arise from the highly polycistronic nature of human mitochondrial pre-mRNA. We propose that resolving these differences requires a 100-fold slower mitochondrial translation rate, illuminating the mitoribosome as a nexus of mitonuclear co-regulation.

Keywords:  LRPPRC; Leighs disease; RNA life cycle; gene regulation; genetic conflict; metabolic regulation; mitochondrial gene expression; mitochondrial translation; mitonuclear balance; organellular biogenesis; oxidative phosphorylation

DOI:  https://doi.org/10.1016/j.molcel.2024.02.028
J Ethnopharmacol. 2024 Mar 20. pii: S0378-8741(24)00356-8. [Epub ahead of print] 118057

Si-Wu-Tang attenuates hepatocyte PANoptosis and M1 polarization of macrophages in non-alcoholic fatty liver disease by influencing the intercellular transfer of mtDNA.

Zhi Ma, Kaihong Xie, Xiaoyong Xue, Jianan Li, Yang Yang, Jianzhi Wu, Yufei Li, Xiaojiaoyang Li.

   ETHNOPHARMACOLOGICAL RELEVANCE: Non-alcoholic fatty liver disease (NAFLD) represents a burgeoning challenge for public health with potential progression to malignant liver diseases. PANoptosis, an avant-garde conceptualization of cell deaths, is closely associated with mitochondrial damage and linked to multiple liver disorders. Si-Wu-Tang (SWT), a traditional Chinese herbal prescription renowned for regulating blood-related disorders and ameliorating gynecological and hepatic diseases, has been demonstrated to alleviate liver fibrosis by regulating bile acid metabolism and immune responses.
AIM OF THE STUDY: However, the mechanisms by which mtDNA is released from PANoptotic hepatocytes, triggering macrophage activation and hepatitis and whether this process can be reversed by SWT remain unclear.
MATERIALS AND METHODS: Here, sophisticated RNA-sequencing complemented by molecular approaches were applied to explore the underlying mechanism of SWT against NAFLD in methionine/choline-deficient diet (MCD)-induced mice and relative in vitro models.
RESULTS: We revealed that SWT profoundly repaired mitochondrial dysfunction, blocked mitochondrial permeability transition and mtDNA released to the cytoplasm, subsequently reversing hepatocyte PANoptosis and macrophage polarization both in MCD-stimulated mice and in vitro. Mechanically, loaded lipids dramatically promoted the opening of mPTP and oligomerization of VDAC2 to orchestrate mtDNA release, which was combined with ZBP1 to promote hepatocyte PANoptosis and also taken by macrophages to trigger M1 polarization via the FSTL1 and PKM2 combination. SWT effectively blocked NOXA signaling and reversed all these detrimental outcomes.
CONCLUSION: Our findings show that SWT protects against hepatitis-mediated hepatocyte PANoptosis and macrophage M1 polarization by influencing intrahepatic synthesis, release and intercellular transfer of mtDNA, suggesting a potential therapeutic strategy for ameliorating NAFLD.

Keywords:  Macrophage activation; Mitochondrial DNA; Non-alcoholic fatty liver disease; PANoptosis; Si-Wu-Tang

DOI:  https://doi.org/10.1016/j.jep.2024.118057
Front Pharmacol. 2024 ;15 1352311

A peptide derived from TID1S rescues frataxin deficiency and mitochondrial defects in FRDA cellular models.

Yi Na Dong, Lucie Vanessa Ngaba, Jacob An, Miniat W Adeshina, Nathan Warren, Johnathan Wong, David R Lynch.

  Friedreich's ataxia (FRDA), the most common recessive inherited ataxia, results from homozygous guanine-adenine-adenine (GAA) repeat expansions in intron 1 of the FXN gene, which leads to the deficiency of frataxin, a mitochondrial protein essential for iron-sulphur cluster synthesis. The study of frataxin protein regulation might yield new approaches for FRDA treatment. Here, we report tumorous imaginal disc 1 (TID1), a mitochondrial J-protein cochaperone, as a binding partner of frataxin that negatively controls frataxin protein levels. TID1 interacts with frataxin both in vivo in mouse cortex and in vitro in cortical neurons. Acute and subacute depletion of frataxin using RNA interference markedly increases TID1 protein levels in multiple cell types. In addition, TID1 overexpression significantly increases frataxin precursor but decreases intermediate and mature frataxin levels in HEK293 cells. In primary cultured human skin fibroblasts, overexpression of TID1S results in decreased levels of mature frataxin and increased fragmentation of mitochondria. This effect is mediated by the last 6 amino acids of TID1S as a peptide made from this sequence rescues frataxin deficiency and mitochondrial defects in FRDA patient-derived cells. Our findings show that TID1 negatively modulates frataxin levels, and thereby suggests a novel therapeutic target for treating FRDA.

Keywords:  ATP; Friedreich ataxia (FRDA); Tid1; frataxin; mitochondrial fragmentation

DOI:  https://doi.org/10.3389/fphar.2024.1352311
Free Radic Biol Med. 2024 Mar 15. pii: S0891-5849(24)00137-0. [Epub ahead of print]216 80-88

mtDNA regulates cGAS-STING signaling pathway in adenomyosis.

Kun Wang, Yi Wen, Xianyun Fu, Shaobin Wei, Shidan Liu, Minmin Chen.

  In various hyperproliferative disorders, damaged mitochondria can release mitochondrial DNA (mtDNA) into the cytoplasm, activating the cGAS-STING signaling pathway and subsequent immune imbalances. Our previous research has demonstrated that hypoxia plays a role in the development of adenomyosis (AM) by inducing mitochondrial dysfunction. However, the precise involvement of the cGAS-STING signaling pathway and mtDNA in AM remains unclear. Therefore, this study aims to investigate the relationship between mtDNA secretion, changes in the cGAS-STING signaling pathway, and the abnormal cellular proliferation observed in AM. We found the cGAS, STING, TBK1, p-TBK1, IRF3, and p-IRF3 proteins levels were significantly elevated in the tissues of patients with AM compared to the control group. Additionally, there was an increase in the expression of the pro-inflammatory cytokines IL-6 and IFN-α in the AM tissues. Hypoxia-induced an increase in the proliferation and migration abilities of endometrial stromal cells (ESCs), accompanied by the activation of the cGAS-STING signaling pathway and elevated levels of IFN-α. Furthermore, hypoxia promoted the leakage of mtDNA into the cytoplasm in AM ESCs, and the deletion of mtDNA reduced the activation of the cGAS-STING pathway. Moreover, knockdown of the STING gene inhibited the expression of TBK1, p-TBK1, IRF3, and p-IRF3 and suppressed the secretion of the inflammatory cytokines IL-6 and IFN-α. Furthermore, the migration and invasion abilities of AM ESCs were significantly diminished after STING knockdown. These findings provide valuable insights into the role of mtDNA release and the cGAS-STING signaling pathway in the pathogenesis of AM.

Keywords:  Adenomyosis; cGAS-STING signaling; mtDNA

DOI:  https://doi.org/10.1016/j.freeradbiomed.2024.03.012
iScience. 2024 Apr 19. 27(4): 109136

Local mitochondrial replication in the periphery of neurons requires the eEF1A1 protein and thetranslation of nuclear-encoded proteins.

Carlos Cardanho-Ramos, Rúben Alves Simões, Yi-Zhi Wang, Andreia Faria-Pereira, Ewa Bomba-Warczak, Katleen Craessaerts, Marco Spinazzi, Jeffrey N Savas, Vanessa A Morais.

  In neurons, it is commonly assumed that mitochondrial replication only occurs in the cell body, after which the mitochondria must travel to the neuron's periphery. However, while mitochondrial DNA replication has been observed to occur away from the cell body, the specific mechanisms involved remain elusive. Using EdU-labelling in mouse primary neurons, we developed a tool to determine the mitochondrial replication rate. Taking of advantage of microfluidic devices, we confirmed that mitochondrial replication also occurs locally in the periphery of neurons. To achieve this, mitochondria require de novo nuclear-encoded, but not mitochondrial-encoded protein translation. Following a proteomic screen comparing synaptic with non-synaptic mitochondria, we identified two elongation factors - eEF1A1 and TUFM - that were upregulated in synaptic mitochondria. We found that mitochondrial replication is impaired upon the downregulation of eEF1A1, and this is particularly relevant in the periphery of neurons.

Keywords:  Biochemistry; Biological sciences; Cellular neuroscience; Molecular neuroscience; Natural sciences; Neuroscience

DOI:  https://doi.org/10.1016/j.isci.2024.109136
Mol Cell. 2024 Mar 21. pii: S1097-2765(24)00174-6. [Epub ahead of print]84(6): 1000-1002

A SIFI odyssey: Silencing the stress response amid mitochondrial import blockade to safeguard cell survival.

Yuleika G Martinez Castillo, Chantell S Evans.

In a recent study in Nature, Haakonsen et al.1 identify the SIFI complex as a stress response silencer via its E3 ligase activity to target unimported mitochondrial proteins and stress response components for degradation via the proteasome.

DOI: https://doi.org/10.1016/j.molcel.2024.02.034
Cell. 2024 Mar 14. pii: S0092-8674(24)00233-2. [Epub ahead of print]

Cellular architecture of evolving neuroinflammatory lesions and multiple sclerosis pathology.

Petra Kukanja, Christoffer M Langseth, Leslie A Rubio Rodríguez-Kirby, Eneritz Agirre, Chao Zheng, Amitha Raman, Chika Yokota, Christophe Avenel, Katarina Tiklová, André O Guerreiro-Cacais, Tomas Olsson, Markus M Hilscher, Mats Nilsson, Gonçalo Castelo-Branco.

  Multiple sclerosis (MS) is a neurological disease characterized by multifocal lesions and smoldering pathology. Although single-cell analyses provided insights into cytopathology, evolving cellular processes underlying MS remain poorly understood. We investigated the cellular dynamics of MS by modeling temporal and regional rates of disease progression in mouse experimental autoimmune encephalomyelitis (EAE). By performing single-cell spatial expression profiling using in situ sequencing (ISS), we annotated disease neighborhoods and found centrifugal evolution of active lesions. We demonstrated that disease-associated (DA)-glia arise independently of lesions and are dynamically induced and resolved over the disease course. Single-cell spatial mapping of human archival MS spinal cords confirmed the differential distribution of homeostatic and DA-glia, enabled deconvolution of active and inactive lesions into sub-compartments, and identified new lesion areas. By establishing a spatial resource of mouse and human MS neuropathology at a single-cell resolution, our study unveils the intricate cellular dynamics underlying MS.

Keywords:  EAE; MS; SERPINA3; Serpina3n; disease-associated glia; experimental autoimmune encephalomyelitis; in situ sequencing; multiple sclerosis; neuroinflammation; neuropathology; single-cell; spatial sequencing

DOI:  https://doi.org/10.1016/j.cell.2024.02.030
Adv Sci (Weinh). 2024 Mar 18. e2307480

AMPK Suppression Due to Obesity Drives Oocyte mtDNA Heteroplasmy via ATF5-POLG Axis.

Yanting Chen, Guiling Ma, Yang Gai, Qiyuan Yang, Xiangdong Liu, Jeanene M de Avila, Shengyong Mao, Mei-Jun Zhu, Min Du.

  Due to the exclusive maternal transmission, oocyte mitochondrial dysfunction reduces fertility rates, affects embryonic development, and programs offspring to metabolic diseases. However, mitochondrial DNA (mtDNA) are vulnerable to mutations during oocyte maturation, leading to mitochondrial nucleotide variations (mtSNVs) within a single oocyte, referring to mtDNA heteroplasmy. Obesity (OB) accounts for more than 40% of women at the reproductive age in the USA, but little is known about impacts of OB on mtSNVs in mature oocytes. It is found that OB reduces mtDNA content and increases mtSNVs in mature oocytes, which impairs mitochondrial energetic functions and oocyte quality. In mature oocytes, OB suppresses AMPK activity, aligned with an increased binding affinity of the ATF5-POLG protein complex to mutated mtDNA D-loop and protein-coding regions. Similarly, AMPK knockout increases the binding affinity of ATF5-POLG proteins to mutated mtDNA, leading to the replication of heteroplasmic mtDNA and impairing oocyte quality. Consistently, AMPK activation blocks the detrimental impacts of OB by preventing ATF5-POLG protein recruitment, improving oocyte maturation and mitochondrial energetics. Overall, the data uncover key features of AMPK activation in suppressing mtSNVs, and improving mitochondrial biogenesis and oocyte maturation in obese females.

Keywords:  AMPK; female obesity; mature oocyte; mtDNA heteroplasmy

DOI:  https://doi.org/10.1002/advs.202307480
DNA Repair (Amst). 2024 Mar 08. pii: S1568-7864(24)00042-9. [Epub ahead of print]137 103666

Mitochondrial transcription factor A (TFAM) has 5'-deoxyribose phosphate lyase activity in vitro.

Wenxin Zhao, Adil S Hussen, Bret D Freudenthal, Zucai Suo, Linlin Zhao.

  Mitochondrial DNA (mtDNA) plays a key role in mitochondrial and cellular functions. mtDNA is maintained by active DNA turnover and base excision repair (BER). In BER, one of the toxic repair intermediates is 5'-deoxyribose phosphate (5'dRp). Human mitochondrial DNA polymerase γ has weak dRp lyase activities, and another known dRp lyase in the nucleus, human DNA polymerase β, can also localize to mitochondria in certain cell and tissue types. Nonetheless, whether additional proteins have the ability to remove 5'dRp in mitochondria remains unknown. Our prior work on the AP lyase activity of mitochondrial transcription factor A (TFAM) has prompted us to examine its ability to remove 5'dRp residues in vitro. TFAM is the primary DNA-packaging factor in human mitochondria and interacts with mitochondrial DNA extensively. Our data demonstrate that TFAM has the dRp lyase activity with different DNA substrates. Under single-turnover conditions, TFAM removes 5'dRp residues at a rate comparable to that of DNA polymerase (pol) β, albeit slower than that of pol λ. Among the three proteins examined, pol λ shows the highest single-turnover rates in dRp lyase reactions. The catalytic effect of TFAM is facilitated by lysine residues of TFAM via Schiff base chemistry, as evidenced by the observation of dRp-lysine adducts in mass spectrometry experiments. The catalytic effect of TFAM observed here is analogous to the AP lyase activity of TFAM reported previously. Together, these results suggest a potential role of TFAM in preventing the accumulation of toxic DNA repair intermediates.

Keywords:  5'-deoxyribose phosphate; DNA repair intermediates; DNA-protein cross-links; abasic sites; base excision repair; mitochondrial DNA

DOI:  https://doi.org/10.1016/j.dnarep.2024.103666
Sci Rep. 2024 Mar 21. 14(1): 6751

MCU-independent Ca2+ uptake mediates mitochondrial Ca2+ overload and necrotic cell death in a mouse model of Duchenne muscular dystrophy.

Michael J Bround, Eaman Abay, Jiuzhou Huo, Julian R Havens, Allen J York, Donald M Bers, Jeffery D Molkentin.

Mitochondrial Ca2+ overload can mediate mitochondria-dependent cell death, a major contributor to several human diseases. Indeed, Duchenne muscular dystrophy (MD) is driven by dysfunctional Ca2+ influx across the sarcolemma that causes mitochondrial Ca2+ overload, organelle rupture, and muscle necrosis. The mitochondrial Ca2+ uniporter (MCU) complex is the primary characterized mechanism for acute mitochondrial Ca2+ uptake. One strategy for preventing mitochondrial Ca2+ overload is deletion of the Mcu gene, the pore forming subunit of the MCU-complex. Conversely, enhanced MCU-complex Ca2+ uptake is achieved by deleting the inhibitory Mcub gene. Here we show that myofiber-specific Mcu deletion was not protective in a mouse model of Duchenne MD. Specifically, Mcu gene deletion did not reduce muscle histopathology, did not improve muscle function, and did not prevent mitochondrial Ca2+ overload. Moreover, myofiber specific Mcub gene deletion did not augment Duchenne MD muscle pathology. Interestingly, we observed MCU-independent Ca2+ uptake in dystrophic mitochondria that was sufficient to drive mitochondrial permeability transition pore (MPTP) activation and skeletal muscle necrosis, and this same type of activity was observed in heart, liver, and brain mitochondria. These results demonstrate that mitochondria possess an uncharacterized MCU-independent Ca2+ uptake mechanism that is sufficient to drive MPTP-dependent necrosis in MD in vivo.

DOI: https://doi.org/10.1038/s41598-024-57340-3
Nat Commun. 2024 Mar 21. 15(1): 2529

Osteocyte mitochondria regulate angiogenesis of transcortical vessels.

Peng Liao, Long Chen, Hao Zhou, Jiong Mei, Ziming Chen, Bingqi Wang, Jerry Q Feng, Guangyi Li, Sihan Tong, Jian Zhou, Siyuan Zhu, Yu Qian, Yao Zong, Weiguo Zou, Hao Li, Wenkan Zhang, Meng Yao, Yiyang Ma, Peng Ding, Yidan Pang, Chuan Gao, Jialun Mei, Senyao Zhang, Changqing Zhang, Delin Liu, Minghao Zheng, Junjie Gao.

Transcortical vessels (TCVs) provide effective communication between bone marrow vascular system and external circulation. Although osteocytes are in close contact with them, it is not clear whether osteocytes regulate the homeostasis of TCVs. Here, we show that osteocytes maintain the normal network of TCVs by transferring mitochondria to the endothelial cells of TCV. Partial ablation of osteocytes causes TCV regression. Inhibition of mitochondrial transfer by conditional knockout of Rhot1 in osteocytes also leads to regression of the TCV network. By contrast, acquisition of osteocyte mitochondria by endothelial cells efficiently restores endothelial dysfunction. Administration of osteocyte mitochondria resultes in acceleration of the angiogenesis and healing of the cortical bone defect. Our results provide new insights into osteocyte-TCV interactions and inspire the potential application of mitochondrial therapy for bone-related diseases.

DOI: https://doi.org/10.1038/s41467-024-46095-0
Biomed Rep. 2024 Apr;20(4): 70

Involvement of retinoic acid‑inducible gene‑I in radiation‑induced senescence of human umbilical vein endothelial cells.

Fuki Sasaki, Hironori Yoshino, Ayumu Kusuhara, Kota Sato, Eichi Tsuruga.

  In 2012, the threshold radiation dose (0.5 Gy) for cardiovascular and cerebrovascular diseases was revised, and this threshold dose may be exceeded during procedures involving radiation such as interventional radiology. Therefore, in addition to regulating radiation dose, it is necessary to develop strategies to prevent and mitigate the development of cardiovascular disease. Cellular senescence is irreversible arrest of cell proliferation. Although cellular senescence is one of the mechanisms for suppressing cancer, it also has adverse effects. For example, senescence of vascular endothelial cells is involved in development of vascular disorders. However, the mechanisms underlying induction of cellular senescence are not fully understood. Therefore, the present study explored the factors involved in the radiation-induced senescence in human umbilical vein endothelial cells (HUVECs). The present study reanalyzed the gene expression data of senescent normal human endothelial cells and fibroblast after irradiation (NCBI Gene Expression Omnibus accession no. GSE130727) and microarray data of HUVECs 24 h after irradiation (NCBI Gene Expression Omnibus accession no. GSE76484). Numerous genes related to viral infection and inflammation were upregulated in radiation-induced senescent cells. In addition, the gene group involved in the retinoic acid-inducible gene-I (RIG-I)-like receptor (RLR) signaling pathway, which plays an important role to induce anti-viral response, was altered in irradiated HUVECs. Therefore, to investigate the involvement of RIG-I and melanoma differentiation-associated gene 5 (MDA5), which are RLRs, in radiation-induced senescence of HUVECs, the protein expression of RIG-I and MDA5 and the activity of senescence-associated β-galactosidase (SA-β-gal), a representative senescence marker, were analyzed. Of note, knockdown of RIG-I in HUVECs significantly decreased radiation-increased proportion of cells with high SA-β-gal activity (i.e., senescent cells), whereas this phenomenon was not observed in MDA5-knockdown cells. Taken together, the present results suggested that RIG-I, but not MDA5, was associated with radiation-induced senescence in HUVECs.

Keywords:  human umbilical vein endothelial cell; ionizing radiation; melanoma differentiation-associated gene 5; retinoic acid-inducible gene-I; senescence

DOI:  https://doi.org/10.3892/br.2024.1758
CNS Neurosci Ther. 2024 Mar;30(3): e14689

Activation of STING signaling aggravates chronic alcohol exposure-induced cognitive impairment by increasing neuroinflammation and mitochondrial apoptosis.

Xinrou Lin, Xiangpen Li, Chenguang Li, Hongxuan Wang, Lubin Zou, Jingrui Pan, Xiaoni Zhang, Lei He, Xiaoming Rong, Ying Peng.

   AIMS: Chronic alcohol exposure leads to persistent neurological disorders, which are mainly attributed to neuroinflammation and apoptosis. Stimulator of IFN genes (STING) is essential in the cytosolic DNA sensing pathway and is involved in inflammation and cellular death processes. This study was to examine the expression pattern and biological functions of STING signaling in alcohol use disorder (AUD).
METHODS: Cell-free DNA was extracted from human and mouse plasma. C57BL/6J mice were given alcohol by gavage for 28 days, and behavior tests were used to determine their mood and cognition. Cultured cells were treated with ethanol for 24 hours. The STING agonist DMXAA, STING inhibitor C-176, and STING-siRNA were used to intervene the STING. qPCR, western blot, and immunofluorescence staining were used to assess STING signaling, inflammation, and apoptosis.
RESULTS: Circulating cell-free mitochondrial DNA (mtDNA) was increased in individuals with AUD and mice chronically exposed to alcohol. Upregulation of STING signaling under alcohol exposure led to inflammatory responses in BV2 cells and mitochondrial apoptosis in PC12 cells. DMXAA exacerbated alcohol-induced cognitive impairment and increased the activation of microglia, neuroinflammation, and apoptosis in the medial prefrontal cortex (mPFC), while C-176 exerted neuroprotection.
CONCLUSION: Activation of STING signaling played an essential role in alcohol-induced inflammation and mitochondrial apoptosis in the mPFC. This study identifies STING as a promising therapeutic target for AUD.

Keywords:  STING; alcohol use disorder; apoptosis; cognitive impairment; neuroinflammation

DOI:  https://doi.org/10.1111/cns.14689
Hepatol Commun. 2024 Apr 01. pii: e0399. [Epub ahead of print]8(4):

ER stress promotes mitochondrial calcium overload and activates the ROS/NLRP3 axis to mediate fatty liver ischemic injury.

Fei Li, Zhu Guan, Yiyun Gao, Yan Bai, Xinyu Zhan, Xingyue Ji, Jian Xu, Haoming Zhou, Zhuqing Rao.

BACKGROUND: Fatty livers are widely accepted as marginal donors for liver transplantation but are more susceptible to liver ischemia and reperfusion (IR) injury. Increased macrophage-related inflammation plays an important role in the aggravation of fatty liver IR injury. Here, we investigate the precise mechanism by which endoplasmic reticulum (ER) stress activates macrophage NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) signaling by regulating mitochondrial calcium overload in fatty liver IR.
METHODS: Control- and high-fat diet-fed mice were subjected to a partial liver IR model. The ER stress, mitochondrial calcium levels, and NLRP3 signaling pathway in macrophages were analyzed.
RESULTS: Liver steatosis exacerbated liver inflammation and IR injury and enhanced NLRP3 activation in macrophages. Myeloid NLRP3 deficiency attenuated intrahepatic inflammation and fatty liver injury following IR. Mechanistically, increased ER stress and mitochondrial calcium overload were observed in macrophages obtained from mouse fatty livers after IR. Suppression of ER stress by tauroursodeoxycholic acid effectively downregulated mitochondrial calcium accumulation and suppressed NLRP3 activation in macrophages, leading to decreased inflammatory IR injury in fatty livers. Moreover, Xestospongin-C-mediated inhibition of mitochondrial calcium influx decreased reactive oxygen species (ROS) expression in macrophages after IR. Scavenging of mitochondrial ROS by mito-TEMPO suppressed macrophage NLRP3 activation and IR injury in fatty livers, indicating that excessive mitochondrial ROS production was responsible for macrophage NLRP3 activation induced by mitochondrial calcium overload. Patients with fatty liver also exhibited upregulated activation of NLRP3 and the ER stress signaling pathway after IR.
CONCLUSIONS: Our findings suggest that ER stress promotes mitochondrial calcium overload to activate ROS/NLRP3 signaling pathways within macrophages during IR-stimulated inflammatory responses associated with fatty livers.

DOI: https://doi.org/10.1097/HC9.0000000000000399
Proc Natl Acad Sci U S A. 2024 Mar 26. 121(13): e2313652121

Mutant huntingtin protein induces MLH1 degradation, DNA hyperexcision, and cGAS-STING-dependent apoptosis.

Xiao Sun, Lu Liu, Chao Wu, Xueying Li, Jinzhen Guo, Junqiu Zhang, Junhong Guan, Nan Wang, Liya Gu, X Willian Yang, Guo-Min Li.

  Huntington's disease (HD) is an inherited neurodegenerative disorder caused by an expanded CAG repeat in the huntingtin (HTT) gene. The repeat-expanded HTT encodes a mutated HTT (mHTT), which is known to induce DNA double-strand breaks (DSBs), activation of the cGAS-STING pathway, and apoptosis in HD. However, the mechanism by which mHTT triggers these events is unknown. Here, we show that HTT interacts with both exonuclease 1 (Exo1) and MutLα (MLH1-PMS2), a negative regulator of Exo1. While the HTT-Exo1 interaction suppresses the Exo1-catalyzed DNA end resection during DSB repair, the HTT-MutLα interaction functions to stabilize MLH1. However, mHTT displays a significantly reduced interaction with Exo1 or MutLα, thereby losing the ability to regulate Exo1. Thus, cells expressing mHTT exhibit rapid MLH1 degradation and hyperactive DNA excision, which causes severe DNA damage and cytosolic DNA accumulation. This activates the cGAS-STING pathway to mediate apoptosis. Therefore, we have identified unique functions for both HTT and mHTT in modulating DNA repair and the cGAS-STING pathway-mediated apoptosis by interacting with MLH1. Our work elucidates the mechanism by which mHTT causes HD.

Keywords:  Exo1; Huntington’s disease; MutLα; cGAS-STING; mHTT

DOI:  https://doi.org/10.1073/pnas.2313652121
Cell Death Differ. 2024 Mar 16.

Sensing of mitochondrial DNA by ZBP1 promotes RIPK3-mediated necroptosis and ferroptosis in response to diquat poisoning.

Kunmei Lai, Junjie Wang, Siyi Lin, Zhimin Chen, Guo Lin, Keng Ye, Ying Yuan, Yujiao Lin, Chuan-Qi Zhong, Jianfeng Wu, Huabin Ma, Yanfang Xu.

Diquat (DQ) poisoning is a severe medical condition associated with life-threatening implications and multiorgan dysfunction. Despite its clinical significance, the precise underlying mechanism remains inadequately understood. This study elucidates that DQ induces instability in the mitochondrial genome of endothelial cells, resulting in the accumulation of Z-form DNA. This process activates Z-DNA binding protein 1 (ZBP1), which then interacts with receptor-interacting protein kinase 3 (RIPK3), ultimately leading to RIPK3-dependent necroptotic and ferroptotic signaling cascades. Specific deletion of either Zbp1 or Ripk3 in endothelial cells simultaneously inhibits both necroptosis and ferroptosis. This dual inhibition significantly reduces organ damage and lowers mortality rate. Notably, our investigation reveals that RIPK3 has a dual role. It not only phosphorylates MLKL to induce necroptosis but also phosphorylates FSP1 to inhibit its enzymatic activity, promoting ferroptosis. The study further shows that deletion of mixed lineage kinase domain-like (Mlkl) and the augmentation of ferroptosis suppressor protein 1 (FSP1)-dependent non-canonical vitamin K cycling can provide partial protection against DQ-induced organ damage. Combining Mlkl deletion with vitamin K treatment demonstrates a heightened efficacy in ameliorating multiorgan damage and lethality induced by DQ. Taken together, this study identifies ZBP1 as a crucial sensor for DQ-induced mitochondrial Z-form DNA, initiating RIPK3-dependent necroptosis and ferroptosis. These findings suggest that targeting the ZBP1/RIPK3-dependent necroptotic and ferroptotic pathways could be a promising approach for drug interventions aimed at mitigating the adverse consequences of DQ poisoning.

DOI: https://doi.org/10.1038/s41418-024-01279-5
Biochem Pharmacol. 2024 Mar 16. pii: S0006-2952(24)00125-4. [Epub ahead of print]223 116142

PLCE1 enhances mitochondrial dysfunction to promote GSDME-mediated pyroptosis in doxorubicin-induced cardiotoxicity.

Maierhaba Tuersuntuoheti, Fei Peng, Juexing Li, Lei Zhou, Hailan Gao, Hui Gong.

   BACKGROUND: The therapeutic value and long-term application of doxorubicin (DOX) were hampered by its severe irreversible cardiotoxicity. Phospholipase C epsilon 1 (PLCE 1) was reported as a new member of the phospholipase C (PLC) family which controls the level of phosphoinositides in cells. Pyroptosis is a newly discovered inflammatory type of regulated cell death. Recent studies have consolidated that chemotherapeutic drugs lead to pyroptosis. Additionally, the phosphoinositide signaling system has remarkable effects on the execution of cell death. We aim to investigate the role of PLCE1 and the mechanism of pyroptosis from the context of DOX-induced cardiotoxicity.
METHODS: In the current study, in vitro and in vivo experiments were performed to dissect the underlying mechanism of cardiomyocyte pyroptosis during DOX-induced cardiac injury. The molecular mechanism of PLCE1 was identified by the human cardiomyocyte AC16 cell line and C57BL/6 mouse model.
RESULTS: The results here indicated that PLCE1 high expressed and pyroptotic cell death presented in cardiomyocytes after DOX application, which was negatively correlated to heart function. DOX-induced cell model disclosed pyroptosis mediated by Gasdermin E (GSDME) protein and involved in mitochondrial damage. Conversely, the deletion of PLCE1 ameliorated mitochondrial dysfunction by suppressing ROS accumulation and reversing mitochondrial membrane potential, and then increased cell viability effectively. More importantly, the in vivo experiment demonstrated that inhibition of PLCE1 reduced pyroptotic cell death and improved heart effect.
CONCLUSIONS: We discovered firstly that PLCE1 inhibition protected cardiomyocytes from DOX-induced pyroptotic injury and promoted cardiac function. This information offers a theoretical basis for promising therapy.

Keywords:  Doxorubicin; Mitochondria; PLCE 1; Phospholipase C epsilon 1; Pyroptosis

DOI:  https://doi.org/10.1016/j.bcp.2024.116142