Zeng et al. report that deficiency in methylthioadenosine phosphorylase (MTAP), a key enzyme in the methionine salvage pathway, sensitizes triple-negative breast cancer to PARP inhibition by reducing s-adenosylmethionine (SAM) and impairing DNA damage repair. The cover art depicts-triple negative breast cancer cells being targeted by a combination of small molecule inhibitors of PARP (green) and MTAP (blue). Image credit: Xiangyu Zeng.
SPNS1 is a lysosomal transporter mediating the salvage of lysoglycerophospholipids, the degradative products of lysosomal phospholipid catabolism. However, a role of lysolipid transport and salvage in regulating cellular lipid homeostasis and in disease is lacking. Here, we identified two families with biallelic SPNS1 loss-of-function variants that presented primarily with progressive liver and striated muscle injury. Patient fibroblasts accumulated lysophospholipids including lysoplasmalogens and cholesterol in lysosomes with reduced cellular plasmalogens. Notably, SPNS1 deficiency resulted in reduced biogenesis of cytosolic lipid droplets containing triglycerides and cholesteryl esters. Mechanistically, we found that lysophospholipids transported by SPNS1 into the cytosol quantitatively contributed to triglyceride synthesis while lysosomal buildup of lyso-ether-phospholipid inhibited lysosomal cholesterol egress, effects that were enhanced with inhibition of mTOR. These findings support a gene-disease association and reveal connectivity between lysosomal transport of lysophospholipids and storage of reserve cellular energy as triglyceride and in the regulation of cholesterol homeostasis, processes that become important under nutrient limitation.
Menglan He, Mei Ding, Michaela Chocholouskova, Cheen Fei Chin, Martin Engvall, Helena Malmgren, Matias Wagner, Marlen C. Lauffer, Jacob Heisinger, May Christine V. Malicdan, Valérie Allamand, Madeleine Durbeej, Angelica M. Delgado-Vega, Thomas Sejersen, Ann Nordgren, Federico Torta, David L. Silver
Perianal fistulizing Crohn’s disease (PCD) is a common and debilitating complication with elusive pathophysiology. To define actionable immunologic targets in PCD, we recruited patients with PCD (n = 24), CD without perianal disease (NPCD, n = 10), and idiopathic/cryptoglandular perianal fistulas (IPF, n = 29). Biopsies from fistula tracts, fistula opening, and rectal mucosa were analyzed using single-cell RNA-sequencing (scRNA-seq), mass cytometry (CyTOF), and spatial transcriptomics (ST). Global hyperactivation of IFN-g pathways distinguished PCD from idiopathic perianal fistulas and CD without perianal disease in the fistula tracts and/or intestinal mucosa. IFN-g and TNF-a signaling directly induced genes involved in epithelial-to-mesenchymal transition in PCD rectal epithelial cells. Enhanced IFN-g signaling in PCD was driven by pathogenic Th17 (pTh17) cells, which were recruited and activated by myeloid cells overexpressing LPS signature (LPS_myeloid). pTh17 and LPS_myeloid cells co-localized adjacent to PCD fistula tracts on ST and drove local IFN-g signaling. Anti-TNFs facilitated fistula healing by downregulating T and myeloid cell signatures, while promoting mucosal barrier repair and immunoregulatory processes. Key single-cell findings were validated by bulk RNA-seq data of an independent CD cohort. To summarize, we identified IFN-g-driven mechanisms contributing to pathogenesis and highlighted its blockade as a therapeutic strategy for PCD.
Siyan Cao, Khai M. Nguyen, Kaiming Ma, Tingyi Tan, Xin Yao, Ta-Chiang Liu, Malek Ayoub, Jalpa Devi, Sami Samaan, Yizhou Liu, Radhika Smith, Matthew L. Silviera, Steven R. Hunt, Paul E. Wise, Matthew G. Mutch, Sean C. Glasgow, William C. Chapman Jr, Michelle L. Cowan, Mathew A. Ciorba, Marco Colonna, Parakkal Deepak
Patients with sickle cell disease (SCD) frequently receive red blood cell (RBC) units stored near the end of their permissible storage life. To evaluate whether storage duration influences recipient metabolism, clinical chemistry and hematological parameters, we conducted a prospective, randomized, blinded trial comparing transfusions of RBC units stored for ≤10 days versus ≥30 days. Chronically transfused adults with SCD (N=24) received three consecutive outpatient transfusions with randomized-age RBCs, and blood samples from units and recipients were analyzed by metabolomics and clinical chemistry. Transfusion of short-stored units resulted in significantly higher circulating levels of 2,3-bisphosphoglycerate, an essential regulator of oxygen unloading, up to two weeks post-transfusion. Conversely, transfusions of long-stored RBCs were associated with lower hemoglobin and RBC increments, higher iron and transferrin saturation, pro-inflammatory cytokines and metabolites, oxidative stress and markers of renal dysfunction. Plasma and RBC metabolomic profiles revealed time- and storage-age-dependent alterations, particularly affecting glycolysis, purine, and sphingolipid metabolism. Transfusion of long-stored RBCs consistently worsened laboratory surrogates of oxygen delivery and RBC efficacy, and increased the circulating levels of immunomodulatory metabolites and pro-inflammatory cytokines. These findings highlight metabolic and hematologic advantages associated with transfusing fresher RBCs in adults with SCD, independent of immediate clinical outcomes.
Matthew S. Karafin, Abby L. Grier, Ross M. Fasano, Anton Ilich, David Wichlan, Ada Chang, Sonjile M. James, Hailly E. Butler, Oleg Kolupaev, Melissa C. Caughey, Daniel J Stephenson, Julie A. Reisz, Nigel S. Key, Joshua J. Field, Jane A. Little, Steven L. Spitalnik, Angelo D’Alessandro
Although virus-like particle (VLPs) vaccines were shown to be effective against several viruses, their advantage over vaccines which include envelope protein only is not completely clear, particularly for mRNA-encoded VLPs. We conducted a side-by-side comparison of the immunogenicity and protective efficacy of mRNA vaccines encoding for the Marburg virus (MARV) full-length GP delivered alone or as a VLP. Electron microscopy confirmed VLP formation when MARV GP and matrix protein VP40 co-expressed. We vaccinated guinea pigs with a two-component mRNA vaccine encoding for GP and VP40 (VLP) or GP alone. At the highest dose, both vaccines protected fully, although the VLP vaccine elicited a slightly lower humoral response than the GP-only group. However, at low doses, GP-only mRNA conferred 100% protection, whereas the VLP exhibited only partial protection. In mice, VLP mRNA induced a moderate preference for GP-specific CD8+ T cells responses, whereas the GP-only mRNA somewhat favored CD4+ T cell responses. Guinea pig whole blood RNA-seq revealed that the VLP vaccine down-regulated genes associated with various biological and metabolic processes, including the NF-κB signaling pathway, whereas the GP-only vaccine upregulated interferon signaling. Overall, the VLP mRNA vaccine was less immunogenic and protective, whereas the GP-only mRNA vaccine conferred robust protection by as little as one µg dose in guinea pigs.
Chandru Subramani, Michelle N. Meyer, Matthew A. Hyde, Margaret E. Comeaux, Haiping Hao, James E. Crowe Jr., Vsevolod L. Popov, Harshwardhan Thaker, Sunny Himansu, Andrea Carfi, Alexander Bukreyev
The spliceosome is a critical cellular machinery responsible for pre-mRNA splicing, essential for the proper expression of genes. Mutations in its core components are increasingly linked to neurodevelopmental disorders, such as primary microcephaly. Here, we investigated the role of SNW1, a spliceosomal protein, in splicing integrity and neurodevelopment. We identified nine heterozygous mutations in the SNW1 gene in patients presenting with primary microcephaly. These mutations impaired SNW1's interactions with core spliceosomal proteins, leading to defective RNA splicing and reduced protein functionality. Using Drosophila melanogaster and human embryonic stem cell-derived cerebral organoids models, we demonstrated that SNW1 depletion resulted in significant reductions in neural stem cell proliferation and increased apoptosis. RNA-sequencing revealed disrupted alternative splicing, especially skipping exons, and altered expression of neurodevelopment-associated genes (CENPE, MEF2C, and NRXN2). Our findings provide crucial insights into the molecular mechanisms by which SNW1 dysfunction contributes to neurodevelopmental disorders and underscore the importance of proper spliceosome function in brain development.
Lei Ji, Jin Yan, Nicole A. Losurdo, Hua Wang, Liangjie Liu, Keyi Li, Zhen Liu, Zhenming Guo, Jing Xu, Adriana Bibo, Decheng Ren, Ke Yang, Yingying Luo, Fengping Yang, Gui Wang, Zhenglong Xiang, Yuan Wang, Huaizhe Zhan, Hu Pan, Juanli Hu, Jianmin Zhong, Rami Abou Jamra, Pia Zacher, Luciana Musante, Flavio Faletra, Paola Costa, Caterina Zanus, Nathalie Couque, Lyse Ruaud, Anna Maria Cueto-González, Hector San Nicolas Fernández, Eduardo Tizzano, Núria Martínez Gil, Xiaorong Liu, Weiping Liao, Layal Abi Farraj, Alden Y. Huang, Liying Zhang, Aparna Murali, Esther Schmuel, Christina S. Han, Kayla King, Weiyue Gu, Pengchao Wang, Kai Li, Nichole Link, Guang He, Shan Bian, Xiao Mao
The complement system executes an evolutionarily ancient innate immune response with important roles in many human diseases, including a variety of conditions involving the kidney, autoimmune disorders, age-related macular degeneration, and more. This series of reviews, curated by Dr. Claudia Kemper, highlights the latest discoveries in complement biology and examines ongoing efforts to target complement therapeutically. From the relatively newly uncovered functions of intracellular complement (complosome) to the complexities involved in using animal models of complementopathies, these reviews convey the challenges of studying complement and developing complement-targeted therapeutics as well as call attention to recent findings that supply momentum to the field.
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