bims-miptne 2026-05-24 papers

Redox Biol. 2026 May 15. pii: S2213-2317(26)00211-9. [Epub ahead of print]94 104213

Nrf2 modulates cytosolic and mitochondrial calcium signal.

Alessandra Preziuso, Artyom Y Baev, Fozila R Rustamova, Sharadha Dayalan Naidu, Lauren Millichap, Plamena R Angelova, Vincenzo Lariccia, Albena T Dinkova-Kostova, Andrey Y Abramov.

Nrf2 is a transcription factor which regulates ∼1% of the mammalian genome and is responsible for orchestrating the cellular defense against oxidative, inflammatory and metabolic stress. Calcium (Ca2+) is a ubiquitous intracellular messenger which controls most cellular processes, from fertilization to cell death. Nrf2 and Ca2+ are involved in a large number of similar physiological processes, but it is not clear if they can regulate each other. Here, using primary co-cultures of neurons and astrocytes we asked if Nrf2 activation or deficiency alters physiological Ca2+ signaling and mitochondrial Ca2+ handling in brain cells. We found that activation of Nrf2 leads to an increase in the amplitude of Ca2+ peak and a faster Ca2+efflux in response to glutamate and ATP in neurons and astrocytes. Interestingly, Nrf2-deficient neurons and astrocytes also had higher Ca2+ peaks in response to glutamate and ATP, but the recovery in neurons was significantly delayed. Genetic (Keap1-knockdown) or pharmacological (ovameloxolone, RTA-408) activation of Nrf2 increases mitochondrial Ca2+ uptake and mitochondrial Ca2+ capacity, and this correlates with increased activity of the Na+/Ca2+/Li+ exchanger (NCLX) and inhibition of the mitochondrial permeability transition pore (mPTP). Conversely, mitochondria in neurons and astrocytes from Nrf2-knockout mice had a lower Ca2+ uptake, lower mitochondrial Ca2+ capacity and lower mitochondrial Ca2+efflux, making these cell vulnerable to Ca2+-induced cell death. Thus, Nrf2 modulates cytosolic calcium signaling and activates the mitochondrial NCLX, increasing the mitochondrial Ca2+ capacity, which adds another critical aspect to the multifaceted nature of Nrf2-mediated cytoprotection.

Keywords: Astrocyte; Calcium signal; Keap1; Mitochondria; Neuron; Nrf2

DOI: https://doi.org/10.1016/j.redox.2026.104213

Autophagy. 2026 May 18.

Organelle contact reorganization drives calcium-dependent autophagy under proteostatic stress.

Yu B Ko, Minjeong Ko, Marius Ueffing, Hye Jin Kang, Ho Jeong Kwon.

Disruption of proteostasis is a defining feature of cancer and other chronic diseases. The AAA+ ATPase VCP/p97 (valosin containing protein) is a key regulator of proteostasis by disassembling ubiquitinated substrates for degradation. VCP overexpression supports cancer cell survival and correlates with poor prognosis, promoting the development of VCP inhibitors as anti-cancer agents. However, the molecular basis for cancer-selective vulnerability of VCP inhibition remains unclear. Here, we demonstrate that allosteric VCP inhibition triggers cell- type specific macroautophagy/autophagy through dynamic reorganization of organelle contact sites. In human umbilical vein endothelial cells (HUVECs), VCP inhibition induces adaptive autophagy through coordinated reorganization of plasma membrane (PM)-ER-mitochondria contacts. Controlled opening of the mitochondrial permeability transition pore (mPTP) releases calcium into the cytosol, activating AMP-activated protein kinase (AMPK) and TFEB pathways, collectively enhancing autophagic flux and sustaining endothelial survival. Critically, calcium-activated kinase inhibitor or calcium chelators blocked VCP inhibitor-induced autophagy in HUVECs, confirming calcium signaling as the central mediator of adaptive autophagy. In contrast, HCT116 colon cancer cells fail to maintain calcium homeostasis under VCP inhibition, leading to mitochondrial calcium overload, defective autophagy, and cell death. Together, our findings identify organelle contact reorganization and calcium homeostasis as key determinants of cell fate under conditions of proteotoxic stress, revealing how VCP inhibition selectively suppresses tumor progression while preserving vascular integrity that could enhance drug delivery and reduce tumor hypoxia.

Keywords: Autophagy; VCP/p97 inhibition; calcium signaling; cancer selectivity; organelle contact reorganization; proteostatic stress

DOI: https://doi.org/10.1080/15548627.2026.2677184

EMBO J. 2026 May 22.

Genetic ablation of neuronal mitochondrial calcium uptake impedes Alzheimer's disease progression.

Pooja Jadiya, Elena Berezhnaya, Devin W Kolmetzky, Dhanendra Tomar, Henry M Cohen, Shatakshi Shukla, Manfred Thomas, Salman Khaledi, Joanne F Garbincius, Liam Kennedy, Oniel Salik, Darpan Raghav, Alycia N Hildebrand, John W Elrod.

Loss of mCa2+ efflux capacity contributes to the pathogenesis and progression of Alzheimer's disease (AD) by promoting mitochondrial Ca2+ (mCa2+) overload. Here, we utilized loss-of-function genetic mouse models to causally evaluate the role of mCa2+ uptake by conditionally deleting the mitochondrial calcium uniporter channel (mtCU) in a robust mouse model of AD. Loss of neuronal mCa2+ uptake reduced Aβ and tau-pathology, synaptic dysfunction, and cognitive decline in 3xTg-AD mice. Knockdown of Mcu in an in vitro model of AD significantly reduced matrix Ca2+ content, redox imbalance, and mitochondrial dysfunction. The preservation of mitochondrial function rescued the AD-dependent decline in autophagic capacity and protected neurons against amyloidosis and cell death. This was corroborated by in vivo data showing improved mitochondrial structure and apposition in AD mice with loss of neuronal Mcu. These results suggest that inhibition of neuronal mCa2+ uptake represents a powerful therapeutic target to impede AD progression.

DOI: https://doi.org/10.1038/s44318-026-00809-w

Mol Biol Rep. 2026 May 22. pii: 817. [Epub ahead of print]53(1):

DDRGK1 regulates muscle development by maintaining mitochondrial calcium homeostasis and oxidative phosphorylation via stabilizing IP3R.

Ping Li, Lingfei Li, Mali Guo, Junjie Xu, Yafei Cai.

BACKGROUND: Mitochondrial calcium homeostasis is essential for oxidative phosphorylation (OXPHOS) and cellular energy production. DDRGK1 is an ER‑localized adaptor protein, which is critical for maintaining ER homeostasis, protein stability, and organelle communication. However, the role of DDRGK1 in regulating mitochondrial function remains largely unknown. This study aims to define the role of DDRGK1 in mitochondrial calcium signaling and bioenergetics.
METHODS AND RESULTS: Through biochemical analyses in cellular models, we identify DDRGK1 as a direct interactor and stabilizer of IP3R, preventing its ubiquitin-mediated degradation. DDRGK1 deficiency reduces IP3R protein levels, impairing mitochondrial calcium uptake and OXPHOS activity, as assessed by respirometry and ATP measurements. Consequent bioenergetic deficits are accompanied by calcium overload-induced ER stress, which activates C/EBP-homologous protein (CHOP) and suppresses the PGC‑1α pathway, thereby inhibiting mitochondrial biogenesis.
CONCLUSIONS: The DDRGK1-IP3R axis constitutes a critical regulatory module in mitochondrial calcium signaling and energy metabolism. Disruption of this axis underlies bioenergetic failure and provides mechanistic insight into the pathogenesis of skeletal muscle metabolic disorders and related mitochondrial diseases.

Keywords: DDRGK1; ER-mitochondrial crosstalk; inositol 1,4,5-trisphosphate receptor; mitochondrial calcium homeostasis; oxidative phosphorylation

DOI: https://doi.org/10.1007/s11033-026-12009-0

Commun Biol. 2026 May 20.

Mitochondrial Ca2+ uniporter (MCU) variants form plasma-membrane channels.

Iuliia Polina, Jyotsna Mishra, Michael W Cypress, Maria Landherr, Nedyalka Valkov, Isabel Chaput, Bridget Nieto, Brian Rhee, Ameneh Ahrari, Nathan DeMichaelis, Kye-Im Jeon, Ulrike Mende, Peng Zhang, Bong Sook Jhun, Jin O-Uchi.

MCU, originally known as CCDC109A, is widely recognized as the gene responsible for encoding a pore-forming subunit of a Ca2+-selective channel, mitochondrial Ca2+ uniporter complex (mtCUC). While MCU expression is typically highly mitochondrial-specific, we report here a protein variant derived from the MCU gene, termed MCU-S, which lacks the mitochondria-targeting sequence (MTS) and forms a Ca2+-permeable channel outside of mitochondria. The mRNA of MCU-S was ubiquitously expressed in all cell types/tissues tested, with particularly high expression in human platelets. MCU-S protein formed Ca2+ channels at the plasma membrane, which exhibited similar channel properties to those observed in mtCUC. MCU-S channels at the plasma membrane served as an additional Ca2+ influx pathway for platelet activation. Our findings show that the MCU-S functions are completely distinct from the originally reported functions of the MCU gene and provide additional insights into the molecular importance of MCU variant-dependent cellular Ca2+ handling.

DOI: https://doi.org/10.1038/s42003-026-10285-x

Biochem Pharmacol. 2026 May 16. pii: S0006-2952(26)00408-9. [Epub ahead of print]251(Pt 1): 118073

Overexpression of GJB1-13k induces mitochondrial calcium overload and triggers apoptosis and GSDME-mediated pyroptosis in cervical cancer.

Shaoyi Cai, Shanshan Wang, Siqin Ling, Meifeng Qi, Shangsen Feng, Jiayi Liu, Yuke Xiang, Changhua Zhang, Liping Huang, Fuhua Peng.

Cervical cancer, the fourth most common female malignancy worldwide, is often diagnosed at advanced stages in developing countries, where survival declines dramatically from 91% to about 17%, underscoring the urgent need for new therapies. In this study, we demonstrated that overexpression of GJB1-13k, a truncated isoform of connexin 32 (Cx32) mediated by an internal ribosome entry site (IRES), significantly inhibited cervical cancer growth both in vitro and in vivo. Mechanistically, we found that GJB1-13k triggers mitochondrial calcium overload, which in turn activates caspase-dependent pathways that induce both apoptosis and GSDME-mediated pyroptosis. Additionally, we identified a physical interaction between GJB1-13k and the inositol 1,4,5-trisphosphate receptor type 3 (ITPR3), an endoplasmic reticulum calcium channel, which may contribute to the observed calcium dysregulation and cell death. Our findings suggest that overexpressing GJB1-13k may represent a promising new strategy for the treatment of cervical cancer.

Keywords: Apoptosis; Caspase; Cervical cancer; GJB1–13k; ITPR3; Pyroptosis

DOI: https://doi.org/10.1016/j.bcp.2026.118073

Microb Pathog. 2026 May 19. pii: S0882-4010(26)00298-6. [Epub ahead of print]217 108572

Treponema pallidum induces intrinsic apoptosis in hepatocytes by facilitating mitochondrial ROS accumulation to promote cardiolipin peroxidation.

Xu Shen, Ze Li, Hui-Lin Zhang, Yu-Yan Chen, Si-Ya Wang, Mi-Jie Gao, Ling-Qing Lin, Tian-Ci Yang.

Liver involvement in the course of syphilis can be observed, and hepatocyte apoptosis is a common mechanism of liver damage, the liver's high metabolic activity and the abundance of mitochondria in hepatocytes suggest that mitochondria-mediated intrinsic apoptosis warrants comprehensive investigation in the course of syphilis. After hepatocytes THLE-2 cells were incubated with Treponema pallidum (T. pallidum), we analyzed intrinsic apoptosis alongside key mitochondrial functional parameters. Mitochondrial cardiolipin peroxidation in THLE-2 cells was measured concurrently. In THLE-2 cells, T. pallidum treatment induced a dose-dependent increase in apoptosis rates (P < 0.01), correlated with the upregulation of key apoptosis-related proteins including Bax/Bcl-2 ratio (P < 0.05), Cyt-c (P < 0.01), Caspase-9 (P < 0.001), Caspase-3 (P < 0.05) and Cleaved-Caspase-3 (P < 0.001). This was accompanied by dose-dependent mitochondrial dysfunction, characterized by loss of mitochondrial membrane potential (P < 0.001), reduced adenosine triphosphate levels (P < 0.001), enhanced mitochondrial permeability transition pore opening (P < 0.01), ROS accumulation (P < 0.01), as well as elevated levels of oxidized cardiolipin (P < 0.05). Furthermore, targeted ROS inhibition reversed the mitochondrial damage, cardiolipin peroxidation, and intrinsic apoptosis (P < 0.05). Treponema pallidum could induces intrinsic apoptosis in hepatocytes. This process is driven by mitochondrial dysfunction and a consequent ROS accumulation, which triggers pivotal cardiolipin peroxidation. It provide valuable insights for further understanding the pathogenic mechanisms of syphilitic hepatitis.

Keywords: Cardiolipin peroxidation; Intrinsic apoptosis; Mitochondria; Reactive oxygen species; Treponema pallidum

DOI: https://doi.org/10.1016/j.micpath.2026.108572

Phytomedicine. 2026 May 13. pii: S0944-7113(26)00520-9. [Epub ahead of print]157 158286

Nuciferine alleviates cerebral ischemia-reperfusion injury by inhibiting mPTP opening via activating the phosphatidylinositol 3-kinase/protein kinase B/glycogen synthase kinase 3 beta pathway.

Hehe Wang, Shengchun Tian, Yanning Dang, Niuniu Wang, Hao Yang, Jierui Yan, Yafei Zhu, Xiaobo Wang, Qipeng Zhao.

BACKGROUND: Emerging pharmacological evidence indicates that nuciferine (NF) exhibits diverse bioactivities, but its role in ameliorating cerebral ischemia-reperfusion injury (CIRI) remains insufficiently studied.
PURPOSE: This study systematically evaluates the therapeutic potential and underlying mechanisms of NF in CIRI using network pharmacology predictions integrated with in vivo and in vitro validation.
METHODS: Network pharmacology was applied to identify potential targets and signaling pathways of NF relevant to CIRI. Molecular docking, molecular dynamics simulations, alanine scanning, density functional theory calculations, and cellular thermal shift assays were used to confirm interactions between NF and core targets. An oxygen and glucose deprivation/reperfusion-induced HT22 cell model and a middle cerebral artery occlusion/reperfusion-induced C57BL/6J mouse model were used to interrogate the predicted targets and pathways. Apoptosis, mitochondrial membrane potential, intracellular reactive oxygen species, and mitochondrial permeability transition pore opening were assessed by flow cytometry, JC-1 staining, DCFH-DA staining, and a calcein fluorescence assay, respectively. Neurological impairment in mice was evaluated using standardized neurological deficit scores. Infarct volume was quantified by 2,3,5-triphenyltetrazolium chloride staining, and histopathological changes were examined by hematoxylin and eosin and Nissl staining. RT-qPCR and western blot were used to measure mRNA and protein expression of key components in the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/glycogen synthase kinase 3 beta (GSK3β) pathway in both in vitro and in vivo models.
RESULTS: The PI3K/Akt/GSK3β signaling pathway was identified through core target screening and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. Molecular docking and molecular dynamics simulations further confirmed that NF exhibited strong binding potential and stability with PI3K, Akt, and GSK3β proteins. Alanine scanning further validated the molecular docking results. Density functional theory calculations showed that NF formed hydrogen bonds and electrostatic interactions with target proteins via its polar regions, and engaged in π-π stacking with aromatic amino acids through its π-conjugated system, providing the structural basis for its binding. Cellular thermal shift assays confirmed that NF enhanced the thermal stability of PI3K protein. The data indicated that NF increased the survival rate of oxygen and glucose deprivation/reperfusion-induced HT22 cells by reducing apoptosis, decreasing reactive oxygen species levels, and maintaining mitochondrial membrane potential stability. Additionally, NF reduced ischemic infarction volume, alleviated histopathological damage, and improved neurological function in middle cerebral artery occlusion/reperfusion mice. RT-qPCR analysis suggested that NF reduced mRNA expression levels of Caspase 3, Caspase 9, Bax/Bcl-2 ratio, and CypD, while increasing PI3K, Akt, and GSK3β mRNA expression. Western blot analysis demonstrated that NF decreased protein expression of Bax/Bcl-2 ratio, cleaved Caspase 3, cleaved Caspase 9, ANT1, CypD, and VDAC1, while increasing expression of p-PI3K, p-Akt, and p-GSK3β.
CONCLUSION: This study suggests that NF's protective effect against CIRI may be attributed to the regulation of the PI3K/Akt/GSK3β signaling pathway, leading to the inhibition of mitochondrial permeability transition pore opening.

Keywords: Cerebral ischemia-reperfusion injury; Ischemic stroke; Mitochondrial permeability transition pore; Nuciferine; PI3K/Akt/GSK3β pathway

DOI: https://doi.org/10.1016/j.phymed.2026.158286

Proc Natl Acad Sci U S A. 2026 May 26. 123(21): e2528689123

Apoptosis-inducing factor starts its activity within mitochondria revealed by in situ vibrational probes.

Jinyu Zhu, Yi Liao, Mengfan Feng, Li Song, Wei Li, Linjun Cai, Xiao Xia Han.

Apoptosis-inducing factor (AIF) is a flavoprotein located in the mitochondrial intermembrane space, and it is believed to trigger caspase-independent cell death after its release from the mitochondria into the nucleus. Here, the proapoptotic activity of AIF within mitochondria and the underlying molecular mechanism are explored using label-free vibrational spectroscopy and imaging. Electron transfer between AIF and cytochrome c (Cyt c) is evidenced by resonance Raman spectroscopy, and the details of their interaction are revealed through molecular dynamics simulations. We elucidate the nicotinamide adenine dinucleotide (NADH)-AIF-dependent generation of reactive oxygen species (ROS) and its correlation with phospholipid peroxidation at the molecular level. With in situ Raman probes, our results verified the synergistic contribution of AIF and Cyt c to mitochondrial membrane permeabilization via a ROS-independent pathway. Remarkably, NADH-dependent Cyt c release from isolated mitochondria is clearly monitored by in situ and real-time Raman spectroscopy, and our findings prove the proapoptotic role of NADH, further supported by flow cytometry. This function of AIF has implications for a deeper understanding of cell death executors and would open up therapeutic strategies for cancer.

Keywords: apoptosis; apoptosis-inducing factor; cytochrome c; electron transfer; phospholipid peroxidation

DOI: https://doi.org/10.1073/pnas.2528689123