Benavides-Nieto et al. report that heterozygous gain-of-function variants in the gene encoding the small GTPase RAP1B lead to thrombocytopenia and immunodeficiency. The cover image shows abnormal spreading and impaired organization of microtubules (green) in B lymphoblastic cells from a patient with the RAP1B gain-of-function variant p.G12E. Image credit: Charlotte Boussard and Béatrice Durel.
Childhood neuroblastoma with MYCN-amplification is classified as high-risk and often relapses after intensive treatments. Immune checkpoint blockade therapy against the PD-1/L1 axis shows limited efficacy in neuroblastoma patients and the cancer intrinsic immune regulatory network is poorly understood. Here, we leverage genome-wide CRISPR/Cas9 screens and identify H2AFY as a resistance gene to the clinically approved PD-1 blocking antibody, nivolumab. Analysis of single-cell RNA sequencing datasets reveals that H2AFY mRNA is enriched in adrenergic cancer cells and is associated with worse patient survival. Genetic deletion of H2afy in MYCN-driven neuroblastoma cells reverts in vivo resistance to PD-1 blockade by eliciting activation of the adaptive and innate immunity. Mapping of the epigenetic and translational landscape demonstrates that H2afy deletion promotes cell transition to a mesenchymal-like state. With a multi-omics approach, we uncover H2AFY-associated genes that are functionally relevant and prognostic in patients. Altogether, our study elucidates the role of H2AFY as an epigenetic gatekeeper for cell states and immunogenicity in high-risk neuroblastoma.
Divya Nagarajan, Rebeca T. Parracho, David Corujo, Minglu Xie, Ginte Kutkaite, Thale K. Olsen, Marta Rúbies Bedós, Maede Salehi, Ninib Baryawno, Michael P. Menden, Xingqi Chen, Marcus Buschbeck, Yumeng Mao
Translation of mRNA to protein is tightly regulated by tRNAs, which are subject to various chemical modifications that maintain the structure, stability and function. Deficiency of tRNA N7-methylguanosine (m7G) modification in patients causes a type of primordial dwarfism, but the underlying mechanism remains unknown. Here we report the loss of m7G rewires cellular metabolism, leading to the pathogenesis of primordial dwarfism. Conditional deletion of the catalytic enzyme Mettl1 or missense mutation of the scaffold protein Wdr4 severely impaired endochondral bone formation and bone mass accrual. Mechanistically, Mettl1 knockout decreased abundance of m7G-modified tRNAs and inhibited translation of mRNAs relating to cytoskeleton and Rho GTPase signaling. Meanwhile, Mettl1 knockout enhanced cellular energy metabolism despite of incompetent proliferation and osteogenic commitment. Further exploration revealed that impaired Rho GTPase signaling upregulated branched-chain amino acid transaminase 1 (BCAT1) level that rewired cell metabolism and restricted intracellular α-ketoglutarate (αKG). Supplementation of αKG ameliorated the skeletal defect of Mettl1-deficient mice. In addition to the selective translation of metabolism-related mRNAs, we further revealed that Mettl1 knockout globally regulated translation via integrated stress response (ISR) and mammalian target of rapamycin complex 1 (mTORC1) signaling. Restoring translation either by targeting ISR or mTORC1 aggravated bone defects of Mettl1-deficient mice. Overall, our study unveils a critical role of m7G tRNA modification in bone development by regulating cellular metabolism, and indicates that suspension of translation initiation as quality control mechanism in response to tRNA dysregulation.
Qiwen Li, Shuang Jiang, Kexin Lei, Hui Han, Yaqian Chen, Weimin Lin, Qiuchan Xiong, Xingying Qi, Xinyan Gan, Rui Sheng, Yuan Wang, Yarong Zhang, Jieyi Ma, Tao Li, Shuibin Lin, Chenchen Zhou, Demeng Chen, Quan Yuan
BACKGROUND. The HIV Organ Policy Equity (HOPE) Act allows individuals living with HIV to accept organs from donors with HIV. This practice widens the pool of available organs, but also presents important virological questions, including the potential for HIV superinfection of the recipient, viral persistence in the kidney, and loss of virological control. METHODS. We addressed these questions by performing in-depth longitudinal viral sequence analyses on urine, blood, and urine-derived renal epithelial cells from twelve recipients of HIV+ kidney allografts. RESULTS. We amplified donor-derived HIV-1 env sequences in 5 out of 12 recipients post-transplant. These donor-derived env sequences were amplified from recipient urine, urine-derived renal epithelial cells, and plasma between 12 and 96-hours post-transplant and remained detectable up to 16-days post-transplant. Env sequences were also detected in kidney biopsies taken from the allografts before implantation in 6 out of the 12 transplant cases, indicating the presence of donor virus within the organ. One recipient had a viremic episode 3.5 years after transplantation as a result of ART interruption. Only recipient strain viral sequences were detected in blood, suggesting that the donor virus, if still present, was not reactivated during the temporary ART withdrawal. CONCLUSIONS. This study demonstrates that the HIV env sequences in a donor kidney can be amplified from biopsies taken from the allograft before implantation and can be detected transiently in blood and urine samples collected from the organ recipients post-transplantation.
Tatianna Travieso, Hannah Stadtler, Naseem Alavian, Feng Gao, Mary Klotman, Cameron R. Wolfe, Maria Blasi
The airway surface liquid (ASL) plays a crucial role in lung defense mechanisms, and its composition and volume are regulated by the airway epithelium. The cystic fibrosis transmembrane conductance regulator (CFTR) is abundantly expressed in a rare airway epithelial cell type called an ionocyte. Recently, we demonstrated that ionocytes can increase liquid absorption through apical CFTR and basolateral barttin/chloride channels, while airway secretory cells mediate liquid secretion through apical CFTR channels and basolateral NKCC1 transporters. Th2-driven (IL-4/IL-13) airway diseases, such as asthma, cause goblet cell metaplasia, accompanied by increased mucus production and airway secretions. In this study, we investigate the effect of IL-13 on chloride and liquid transport performed by ionocytes. IL-13 treatment of human airway epithelia was associated with reduced epithelial liquid absorption rates and increased ASL volume. Additionally, IL-13 treatment reduced the abundance of CFTR-positive ionocytes and increased the abundance of CFTR-positive secretory cells. Increasing ionocyte abundance attenuated liquid secretion caused by IL-13. Finally, CFTR-positive ionocytes were less common in asthma and COPD and associated with airflow obstruction. Our findings suggest that loss of CFTR in ionocytes contributes to the liquid secretion observed in IL-13-mediated airway diseases.
Guillermo S. Romano Ibarra, Lei Lei, Wenjie Yu, Andrew L. Thurman, Nicholas D. Gansemer, David K. Meyerholz, Alejandro A. Pezzulo, Paul B. McCray, Ian M. Thornell, David A. Stoltz
A leading cause of mortality after influenza infection is the development of a secondary bacterial pneumonia. In the absence of a bacterial superinfection, prescribing antibacterial therapies is not indicated but has become a common clinical practice for those presenting with a respiratory viral illness. In a murine model, we found that antibiotic use during influenza infection impaired the lung innate immunologic defenses toward a secondary challenge with methicillin-resistant Staphylococcus aureus (MRSA). Antibiotics augment lung eosinophils, which have inhibitory effects on macrophage function through the release of major basic protein. Moreover, we demonstrated antibiotic treatment during influenza infection causes a fungal dysbiosis that drive lung eosinophilia and impair MRSA clearance. Finally, we evaluated three cohorts of hospitalized patients and found eosinophils positively correlated with antibiotic use, systemic inflammation, and worsened outcomes. Altogether, our work demonstrates a detrimental effect of antibiotic treatment during influenza infection that has harmful immunologic consequences via recruitment of eosinophils to the lungs thereby increasing the risk of developing a secondary bacterial infection.
Marilia Sanches Santos Rizzo Zuttion, Tanyalak Parimon, Stephanie A. Bora, Changfu Yao, Katherine Lagree, Catherine A. Gao, Richard G. Wunderink, Georgios D. Kitsios, Alison Morris, Yingze Zhang, Bryan J. McVerry, Matthew E. Modes, Alberto M. Marchevsky, Barry R. Stripp, Christopher M. Soto, Ying Wang, Kimberly Merene, Silvia Cho, Blandine L. Victor, Ivan Vujkovic-Cvijin, Suman Gupta, Suzanne Cassel, Fayyaz S. Sutterwala, Suzanne Devkota, David M. Underhill, Peter Chen
JCI celebrates a century of publishing scientific discoveries with a special collection highlighting major innovations in medicine and key contributing mechanistic studies.
Vascular malformations in arteries, veins, and lymphatic vessels occur in a broad range of conditions that vary widely in severity and presentation. Leveraging the mechanisms specific to each type of malformation will be essential for optimizing disease management. This review series, developed with series editor Miikka Vikkula, will span hemangioma, hereditary hemorrhagic telangiectasia, lymphatic abnormalities, cerebral small vessel disease, capillary malformations, and more, with reviews contributed by leading experts in each condition.
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