A deep intronic mutation causes RAD50 deficiency through an unusual mechanism of distant exon activation

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Abstract

Authors

Kristine Bousset, Stefano Donega, Najim Ameziane, Tabea Fleischhammer, Dhanya Ramachandran, Miriam Poley-Gil, Detlev Schindler, Ingrid M. van de Laar, Franco Pagani, Thilo Dörk

Palmitoylation acts as a checkpoint for MAVS aggregation to promote antiviral innate immune responses

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Abstract

Upon RNA virus infection, the signaling adaptor MAVS forms functional prion-like aggregates on the mitochondrial outer membrane, which serve as a central hub that links virus recognition to downstream antiviral innate immune responses. Multiple mechanisms regulating MAVS activation have been revealed; however, the checkpoint governing MAVS aggregation remains elusive. Here, we demonstrated that the palmitoylation of MAVS at cysteine 79 (C79), which is catalyzed mainly by the palmitoyl S-acyltransferase ZDHHC12, was essential for MAVS aggregation and antiviral innate immunity upon viral infection in macrophages. Notably, the systemic lupus erythematosus–associated mutation MAVS C79F was associated with defective palmitoylation, resulting in low type I interferon (IFN) production. Accordingly, Zdhhc12 deficiency apparently impaired RNA virus–induced type I IFN responses, and Zdhhc12-deficient mice were highly susceptible to lethal viral infection. These findings reveal a previously unknown mechanism by which the palmitoylation of MAVS is a checkpoint for its aggregation during viral infection to ensure timely activation of antiviral defense.

Authors

Liqiu Wang, Mengqiu Li, Guangyu Lian, Shuai Yang, Jing Cai, Zhe Cai, Yaoxing Wu, Jun Cui

NEUROPILIN-1 INHIBITION SUPPRESSES NERVE-GROWTH FACTOR SIGNALING AND NOCICEPTION IN PAIN MODELS

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Abstract

Nerve growth factor (NGF) monoclonal antibodies inhibit chronic pain yet failed to gain approval due to worsened joint damage in osteoarthritis patients. We report that neuropilin-1 (NRP1) is a co-receptor for NGF and tropomyosin-related kinase A (TrkA) pain signaling. NRP1 was coexpressed with TrkA in human and mouse nociceptors. NRP1 inhibitors suppressed NGF-stimulated excitation of human and mouse nociceptors and NGF-evoked nociception in mice. NRP1 knockdown inhibited NGF/TrkA signaling, whereas NRP1 overexpression enhanced signaling. NGF bound NRP1 with high affinity and interacted with and chaperoned TrkA from the biosynthetic pathway to the plasma membrane and endosomes, enhancing TrkA signaling. Molecular modeling suggested that C-terminal R/KXXR/K NGF motif interacts with extracellular “b” NRP1 domain within a plasma membrane NGF/TrkA/NRP1 of 2:2:2 stoichiometry. G Alpha Interacting Protein C-terminus 1 (GIPC1), which scaffolds NRP1 and TrkA to myosin VI, colocalized in nociceptors with NRP1/TrkA. GIPC1 knockdown abrogated NGF-evoked excitation of nociceptors and pain-like behavior. Thus, NRP1 is a nociceptor-enriched co-receptor that facilitates NGF/TrkA pain signaling. NRP binds NGF and chaperones TrkA to the plasma membrane and signaling endosomes via GIPC1 adaptor. NRP1 and GIPC1 antagonism in nociceptors offers a long-awaited non-opioid alternative to systemic antibody NGF sequestration for the treatment of chronic pain.

Authors

Chloe J. Peach, Raquel Tonello, Elisa Damo, Kimberly Gomez, Aida Calderon-Rivera, Renato Bruni, Harsh Bansia, Laura Maile, Ana-Marie Manu, Hyunggu Hahn, Alex R.B. Thomsen, Brian L. Schmidt, Steve Davidson, Amedee des Georges, Rajesh Khanna, Nigel W. Bunnett

Low tristetraprolin expression activates phenotypic plasticity and primes transition to lethal prostate cancer in mice

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Phenotypic plasticity is a hallmark of cancer and increasingly realized as a mechanism of resistance to androgen receptor (AR)-targeted therapy. Now that many prostate cancer (PCa) patients are treated upfront with AR-targeted agents, it’s critical to identify actionable mechanisms that drive phenotypic plasticity, to prevent the emergence of resistance. We showed that loss of tristetraprolin (TTP, gene ZFP36) increased NF-κB activation, and was associated with higher rates of aggressive disease and early recurrence in primary PCa. We also examined the clinical and biological impact of ZFP36 loss with co-loss of PTEN, a known driver of PCa. Analysis of multiple independent primary PCa cohorts demonstrated that PTEN and ZFP36 co-loss was associated with increased recurrence risk. Engineering prostate-specific Zfp36 deletion in vivo, induced prostatic intraepithelial neoplasia, and, with Pten co-deletion, resulted in rapid progression to castration-resistant adenocarcinoma. Zfp36 loss altered the cell state driven by Pten loss, demonstrated by enrichment of EMT, inflammation, TNFα/NF-κB, IL6-JAK/STAT3 gene sets. Additionally, our work revealed that ZFP36 loss also induced enrichment of multiple gene sets involved in mononuclear cell migration, chemotaxis, and proliferation. Use of the NF-κB inhibitor, dimethylaminoparthenolide (DMAPT) induced marked therapeutic responses in tumors with PTEN and ZFP36 co-loss and reversed castration resistance.

Authors

Katherine L. Morel, Beatriz Germán, Anis A. Hamid, Jagpreet S. Nanda, Simon Linder, Andries M. Bergman, Henk van der Poel, Ingrid Hofland, Elise M. Bekers, Shana Y. Trostel, Deborah L. Burkhart, Scott Wilkinson, Anson T. Ku, Minhyung Kim, Jina Kim, Duanduan Ma, Jasmine T. Plummer, Sungyong You, Xiaofeng A. Su, Wilbert Zwart, Adam G. Sowalsky, Christopher J. Sweeney, Leigh Ellis

Nuclear PD-L1 compartmentalization suppresses tumorigenesis and overcomes immunocheckpoint therapy resistance in mice via histone macroH2A1

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Canonically PD-L1 functions as the inhibitory immune checkpoint on cell surface. Recent studies have observed PD-L1 expression in the nucleus of cancer cells. But the biological function of nuclear PD-L1 (nPD-L1) in tumor growth and antitumor immunity is unclear. Here we enforced nPD-L1 expression and established stable cells. nPD-L1 suppressed tumorigenesis and aggressiveness in vitro and in vivo. Compared with PD-L1 deletion, nPD-L1 expression repressed tumor growth and improved survival more markedly in immunocompetent mice. Phosphorylated AMPKα (p-AMPKα) facilitated nuclear PD-L1 compartmentalization and then cooperated with it to directly phosphorylate S146 of histone variant macroH2A1 (mH2A1) to epigenetically activate expression of genes of cellular senescence, JAK/STAT, and Hippo signaling pathways. Lipoic acid (LA) that induced nuclear PD-L1 translocation suppressed tumorigenesis and boosted antitumor immunity. Importantly, LA treatment synergized with PD-1 antibody and overcame immune checkpoint blockade (ICB) resistance, which likely resulted from nPD-L1–increased MHC-I expression and sensitivity of tumor cells to interferon-γ. These findings offer a conceptual advance for PD-L1 function and suggest LA as a promising therapeutic option for overcoming ICB resistance.

Authors

Yong Liu, Zhi Yang, Shuanglian Wang, Rui Miao, Chiung-Wen Mary Chang, Jingyu Zhang, Xin Zhang, Mien-Chie Hung, Junwei Hou

Combined HDAC8 and checkpoint kinase inhibition induces tumor-selective synthetic lethality in preclinical models

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The elevated level of replication stress is an intrinsic characteristic of cancer cells. Targeting the mechanisms that maintain genome stability to further increase replication stress and thus induce severe genome instability has become a promising approach for cancer treatment. Here, we identify histone deacetylase 8 (HDAC8) as a drug target whose inactivation synergizes with the inhibition of checkpoint kinases to elicit substantial replication stress and compromise genome integrity selectively in cancer cells. We showed that simultaneous inhibition of HDAC8 and checkpoint kinases led to extensive replication fork collapse, irreversible cell-cycle arrest, and synergistic vulnerability in various cancer cells. The efficacy of the combination treatment was further validated in patient tumor-derived organoid (PDO) and xenograft mouse (PDX) models, providing important insights into patient-specific drug responses. Our data revealed that HDAC8 activity was essential for reducing the acetylation level of structural maintenance of chromosomes protein 3 (SMC3) ahead of replication forks and preventing R loop formation. HDAC8 inactivation resulted in slowed fork progression and checkpoint kinase activation. Our findings indicate that HDAC8 guards the integrity of the replicating genome, and the cancer-specific synthetic lethality between HDAC8 and checkpoint kinases provides a promising replication stress-targeting strategy for treating a broad range of cancers.

Authors

Ting-Yu Chang, Yan Yan, Zih-Yao Yu, Moeez Rathore, Nian-Zhe Lee, Hui-Ju Tseng, Li-Hsin Cheng, Wei-Jan Huang, Wei Zhang, Ernest R. Chan, Yulan Qing, Ming-Lun Kang, Rui Wang, Kelvin K. Tsai, John J. Pink, William E. Harte, Stanton L. Gerson, Sung-Bau Lee

EMC3 regulates trafficking and pulmonary toxicity of the SFTPC^I73T mutation associated with interstitial lung disease

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The most common mutation in surfactant protein C gene (SFTPC), SFTPCI73T, causes interstitial lung disease with few therapeutic options. We previously demonstrated that EMC3, an important component of the multiprotein endoplasmic reticulum membrane complex (EMC), is required for surfactant homeostasis in alveolar type 2 epithelial (AT2) cells at birth. In the present study, we investigated the role of EMC3 in the control of SFTPCI73T metabolism and its associated alveolar dysfunction. Using a knock-in mouse model phenocopying the I73T mutation, we demonstrated that conditional deletion of Emc3 in AT2 cells rescued alveolar remodeling/simplification defects in neonatal and adult mice. Proteomic analysis revealed that Emc3 depletion reversed the disruption of vesicle trafficking pathways and rescued the mitochondrial dysfunction associated with I73T mutation. Affinity purification-mass spectrometry analysis identified potential EMC3 interacting proteins in lung AT2 cells, including Valosin Containing Protein (VCP) and its interactors. Treatment of SftpcI73T knock-in mice and SFTPCI73T expressing iAT2 cells derived from SFTPCI73T patient-specific iPSCs with the specific VCP inhibitor CB5083 restored alveolar structure and SFTPCI73T trafficking respectively. Taken together, the present work identifies the EMC complex and VCP in the metabolism of the disease-associated SFTPCI73T mutant, providing novel therapeutical targets for SFTPCI73T-associated interstitial lung disease.

Authors

Xiaofang Tang, Wei Wei, Yuqing Sun, Timothy E. Weaver, Ernesto S. Nakayasu, Geremy Clair, John M. Snowball, Cheng-Lun Na, Karen S. Apsley, Emily P. Martin, Darrell N. Kotton, Konstantinos-Dionysios Alysandratos, Jiuzhou Huo, Jeffery D. Molkentin, William A. Gower, Xinhua Lin, Jeffrey A. Whitsett

Neuropilin-2 expressing cells in breast cancer are S-nitrosylation hubs that mitigate radiation-induced oxidative stress

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The high rate of recurrence after radiation therapy in triple-negative breast cancer (TNBC) indicates that novel approaches and targets are needed to enhance radiosensitivity. Here, we report that neuropilin-2 (NRP2), a receptor for vascular endothelial growth factor (VEGF) that is enriched on sub-populations of TNBC cells with stem cell properties, is an effective therapeutic target for sensitizing TNBC to radiotherapy. Specifically, VEGF/NRP2 signaling induces nitric oxide synthase 2 (NOS2) transcription by a mechanism dependent on Gli1. NRP2-expressing tumor cells serve as a hub to produce nitric oxide (NO), an autocrine and paracrine signaling metabolite, which promotes cysteine-nitrosylation of Kelch-like ECH-asssociated protein 1 (KEAP1) and, consequently, nuclear factor erythroid 2-related factor 2 (NFE2L2)-mediated transcription of antioxidant response genes. Inhibiting VEGF binding to NRP2, using a humanized monoclonal antibody (mAb), results in NFE2L2 degradation via KEAP1 rendering cell lines and organoids vulnerable to irradiation. Importantly, treatment of patient-derived xenografts with the NRP2 mAb and radiation resulted in significant tumor necrosis and regression compared to radiation alone. Together, these findings reveal a targetable mechanism of radioresistance and they support the use of NRP2 mAb as an effective radiosensitizer in TNBC.

Authors

Ayush Kumar, Hira Goel, Christi Wisniewski, Tao Wang, Yansong Geng, Mengdie Wang, Shivam Goel, Kai Hu, Rui Li, Lihua J. Zhu, Jennifer L. Clark, Lindsay M. Ferreira, Michael Brehm, Thomas J. Fitzgerald, Arthur M. Mercurio

Modeling primary microcephaly with human brain organoids reveals fundamental roles of CIT kinase activity

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Brain size and cellular heterogeneity are tightly regulated by species-specific proliferation and differentiation of multipotent neural progenitor cells (NPCs). Errors in this process are among the mechanisms of primary hereditary microcephaly (MCPH), a group of disorders characterized by reduced brain size and intellectual disability. Biallelic CIT missense variants that disrupt kinase function (CITKI/KI) and frameshift loss-of-function variants (CITFS/FS) are the genetic basis for MCPH17; however, the function of CIT catalytic activity in brain development and NPC cytokinesis is unknown. Therefore, we created the CitKI/KI mouse model and found that it does not phenocopy human microcephaly, unlike biallelic CitFS/FS animals. Nevertheless, both Cit models exhibited binucleation, DNA damage, and apoptosis. To investigate human-specific mechanisms of CIT microcephaly, we generated CITKI/KI and CITFS/FS human forebrain organoids. We found that CITKI/KI and CITFS/FS organoids lose cytoarchitectural complexity, transitioning from pseudostratified to simple neuroepithelium. This change was associated with defects that disrupt polarity of NPC cytokinesis, in addition to elevating apoptosis. Together, our results indicate that both CIT catalytic and scaffolding functions in NPC cytokinesis are critical for human corticogenesis. Species differences in corticogenesis and the dynamic 3D features of NPC mitosis underscore the utility of human forebrain organoid models for understanding human microcephaly.

Authors

Gianmarco Pallavicini, Amanda Moccia, Giorgia Iegiani, Roberta Parolisi, Emily R. Peirent, Gaia Elena Berto, Martina Lorenzati, Rami Y. Tshuva, Alessia Ferraro, Fiorella Balzac, Emilia Turco, Shachi U. Salvi, Hedvig F. Myklebust, Sophia Wang, Julia Eisenberg, Maushmi Chitale, Navjit S. Girgla, Enrica Boda, Orly Reiner, Annalisa Buffo, Ferdinando Di Cunto, Stephanie L. Bielas

Proton-Activated Chloride Channel Increases Endplate Porosity and Pain in a Mouse Spinal Degeneration Model

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Chronic low back pain (LBP) can severely affect daily physical activity. Aberrant osteoclast-mediated resorption leads to porous endplates for the sensory innervation to cause LBP. Here, we report that the expression of proton-activated chloride (PAC) channel is induced during osteoclast differentiation in the porous endplates via a RANKL-NFATc1 signaling pathway. Extracellular acidosis evokes robust PAC currents in osteoclasts. An acidic environment of porous endplates and elevated PAC activation-enhanced osteoclast fusion provoke LBP. Further, we find that genetic knockout of PAC gene Pacc1 significantly reduces endplate porosity and spinal pain in a mouse LBP model, but it does not affect bone development or homeostasis of bone mass in adult mice. Moreover, both osteoclast bone resorptive compartment environment and PAC traffic from the plasma membrane to endosomes to form an intracellular organelle Cl channel have low pH around 5.0. The low pH environment activates PAC channel to increase sialyltransferase St3gal1 expression and sialylation of TLR2 in initiation of osteoclast fusion. Aberrant osteoclast-mediated resorption is also found in most skeletal disorders, including osteoarthritis, ankylosing spondylitis, rheumatoid arthritis, heterotopic ossification, enthesopathy. Thus, elevated Pacc1 expression and PAC activity could be a potential therapeutic target for LBP and osteoclast-associated pain.

Authors

Peng Xue, Weixin Zhang, Mengxi Shen, Junhua Yang, Jiachen Chu, Shenyu Wang, Mei Wan, Junying Zheng, Zhaozhu Qiu, Xu Cao