IKZF1 and UBR4 gene variants drive autoimmunity and TH2 polarization in IgG4-related disease

• Text
• PDF

Abstract

Immunoglobulin G4-related disease (IgG4-RD) is a systemic immune-mediated’ fibroinflammatory disease. The pathomechanisms remain poorly understood. Here, we identified gene variants in familial IgG4-RD and determined their functional consequences. All three affected members shared mutations of the transcription factor IKAROS, encoded by IKZF1, and the E3 ubiquitin ligase UBR4. The IKAROS mutation increased binding to the FYN promoter resulting in higher transcription of FYN in T cells. The UBR4 mutation prevented the lysosomal degradation of the phosphatase CD45. In the presence of elevated FYN, CD45 functioned as a positive regulatory loop, lowering the threshold for T cell activation. Consequently, T cells from affected family members were hyperresponsive to stimulation. When transduced with a low avidity, autoreactive T cell receptor, they responded to the autoantigenic peptide. In parallel, the high expression of FYN in T cells biased their differentiation towards TH2 polarization by stabilizing the transcription factor JunB. This bias is consistent with the frequent atopic manifestations in IgG4-RD patients including our afflicted family members. Building on the functional consequences of these two mutations, we propose a disease model that is not only instructive for IgG4-RD but also for atopic diseases for autoimmune diseases associated with an IKZF1 risk haplotype.

Authors

Qingxiang Liu, Yanyan Zheng, Ines Sturmlechner, Abhinav Jain, Maryam Own, Qiankun Yang, Huimin Zhang, Filippo Pinto e Vairo, Karen Cerosaletti, Jane H. Buckner, Kenneth J. Warrington, Matthew J. Koster, Cornelia M. Weyand, Jorg J. Goronzy

The IFITM5 mutation in osteogenesis imperfecta type V is associated with an ERK/SOX9-dependent osteoprogenitor differentiation defect

• Text
• PDF

Abstract

Osteogenesis imperfecta (OI) type V is the second most common form of OI, distinguished by hyperplastic callus formation and calcification of the interosseous membranes in addition to bone fragility. It is caused by a recurrent, dominant pathogenic variant (c.-14C>T) in IFITM5. Here, we generated a conditional Rosa26 knock-in mouse model to study the mechanistic consequences of the recurrent mutation. Expression of the mutant Ifitm5 in osteo-chondroprogenitor or chondrogenic cells resulted in low bone mass and growth retardation. Mutant limbs showed impaired endochondral ossification, cartilage overgrowth, and abnormal growth plate architecture. The cartilage phenotype correlates with the pathology reported in OI type V patients. Surprisingly, expression of mutant Ifitm5 in mature osteoblasts caused no obvious skeletal abnormalities. In contrast, earlier expression in osteo-chondroprogenitors was associated with increase in the skeletal progenitor population within the periosteum. Lineage tracing showed that chondrogenic cells expressing the mutant Ifitm5 showed decreased differentiation into osteoblastic cells in diaphyseal bone. Moreover, mutant IFITM5 disrupts early skeletal homeostasis in part by activating ERK signaling and downstream SOX9 protein, and inhibition of these pathways partially rescued the phenotype in mutant animals. These data identify the contribution of a signaling defect altering osteo-chondroprogenitor differentiation as a driver in the pathogenesis of OI type V.

Authors

Ronit Marom, I-Wen Song, Emily C. Busse, Megan E. Washington, Ava S. Berrier, Vittoria C. Rossi, Laura Ortinau, Youngjae Jeong, Ming-Ming Jiang, Brian C. Dawson, Mary Adeyeye, Carolina Leynes, Caressa D. Lietman, Bridget M. Stroup, Dominyka Batkovskyte, Mahim Jain, Yuqing Chen, Racel Cela, Alexis Castellon, Alyssa A. Tran, Isabel Lorenzo, D. Nicole Meyers, Shixia Huang, Alicia Turner, Vinitha Shenava, Maegen Wallace, Eric Orwoll, Dongsu Park, Catherine G. Ambrose, Sandesh C.S. Nagamani, Jason D. Heaney, Brendan H. Lee

Triptolide and its pro-drug Minnelide target high-risk MYC amplified medulloblastoma in preclinical models

• Text
• PDF

Abstract

Most children with medulloblastoma (MB) achieve remission, but some face very aggressive metastatic tumors. Their dismal outcome highlights the critical need to advance therapeutic approaches that benefit such high-risk patients. Minnelide, a clinically relevant analog of the natural product triptolide, has oncostatic activity in both preclinical and early clinical settings. Despite its efficacy and tolerable toxicity, this compound has not been evaluated in MB. Utilizing a bioinformatic dataset that integrates cellular drug response data with gene expression, we predicted that Group 3 (G3) MB, which has a poor five-year survival, would be sensitive to triptolide/Minnelide. We subsequently showed that both triptolide and Minnelide attenuate the viability of G3 MB cells ex vivo. Transcriptomic analyses identified MYC signaling, a pathologically relevant driver of G3 MB, as a downstream target of this class of drugs. We validated this MYC dependency in G3 MB cells and showed that triptolide exerts its efficacy by reducing both MYC transcription and MYC protein stability. Importantly, Minnelide acted on MYC to reduce tumor growth and leptomeningeal spread, which resulted in improved survival of G3 MB animal models. Moreover, Minnelide improved the efficacy of adjuvant chemotherapy, further highlighting its potential for the treatment of MYC-driven G3 MB patients.

Authors

Jezabel Rodriguez-Blanco, April D. Salvador, Robert K. Suter, Marzena Swiderska-Syn, Isabel Palomo-Caturla, Valentin Kliebe, Pritika Shahani, Kendell Peterson, Maria Turos-Cabal, Megan E. Vieira, Daniel T. Wynn, Ashley J. Howell, Fan Yang, Yuguang Ban, Heather J. McCrea, Frederique Zindy, Etienne Danis, Rajeev Vibhakar, Anna Jermakowicz, Vanesa Martin, Christopher C. Coss, Brent T. Harris, Aguirre de Cubas, X. Steven Chen, Thibaut Barnoud, Martine F. Roussel, Nagi G. Ayad, David J. Robbins

Beneficial islet inflammation in health depends on pericytic TLR/MyD88 signaling

• Text
• PDF

Abstract

While inflammation is beneficial for insulin secretion during homeostasis, its transformation adversely affects β-cells and contributes to diabetes. However, the regulation of islet inflammation for maintaining glucose homeostasis remains largely unknown. Here, we identified pericytes as pivotal regulators of islet immune and β-cell function in health. Islets and pancreatic pericytes express various cytokines in healthy humans and mice. To interfere with the pericytic inflammatory response, we selectively inhibited the TLR/MyD88 pathway in these cells in transgenic mice. The loss of MyD88 impaired pericytic cytokine production. Furthermore, MyD88-deficient mice exhibited skewed islet inflammation with fewer cells, an impaired macrophage phenotype, and reduced IL-1β production. This aberrant pericyte-orchestrated islet inflammation was associated with β-cell dedifferentiation and impaired glucose response. Additionally, we found that Cxcl1, a pericytic MyD88-dependent cytokine, promoted immune IL-1β production. Treatments with either Cxcl1 or IL-1β restored the mature β-cell phenotype and glucose response in transgenic mice, suggesting a potential mechanism through which pericytes and immune cells regulate glucose homeostasis. Our study revealed pericyte-orchestrated islet inflammation as a crucial element in glucose regulation, implicating this process as a potential therapeutic target for diabetes.

Authors

Anat Schonblum, Dunia Ali Naser, Shai Ovadia, Mohammed Egbaria, Shani Puyesky, Alona Epshtein, Tomer Wald, Sophia Mercado-Medrez, Ruth Ashery-Padan, Limor Landsman

Liver cancer initiation requires translational activation by an oncofetal regulon involving LIN28 proteins

• Text
• PDF

Abstract

It is unknown which post-transcriptional regulatory mechanisms are required for oncogenic competence. Here, we show that the LIN28 family of RNA-binding proteins (RBPs), which facilitate post-transcriptional RNA metabolism within ribonucleoprotein networks, are essential for the initiation of diverse oncotypes of hepatocellular carcinoma (HCC). In HCC models driven by NRASG12V/Tp53, CTNNB1/YAP/Tp53, or AKT/Tp53, mice without Lin28a and Lin28b were markedly impaired in cancer initiation. We biochemically defined an oncofetal regulon of 15 factors connected to Lin28 through direct mRNA and protein interactions. Interestingly, all were RBPs and only 1 of 15 is a Let-7 target. Polysome profiling and reporter assays showed that LIN28B directly increased the translation of 8 of these 15 RBPs. As expected, overexpression of LIN28B and IGFBP1-3 were able to genetically rescue cancer initiation. Using this platform to probe components downstream of LIN28, we found that 8 target RBPs were able to restore NRASG12V/Tp53 cancer formation in Lin28a/b deficient mice. Furthermore, these LIN28B targets promote cancer initiation through an increase in protein synthesis. LIN28B, central to an RNP regulon that increases translation of RBPs, is important for tumor initiation in the liver.

Authors

Meng-hsiung Hsieh, Yonglong Wei, Lin Li, Liem H. Nguyen, Yu-Hsuan Lin, Jung M. Yoon, Xuxu Sun, Xun Wang, Xin Luo, Sarah K. Knutson, Christina Bracken, George Q. Daley, John T. Powers, Hao Zhu

Neomorphic Gαo mutations gain interaction with Ric8 proteins in GNAO1 encephalopathies

• Text
• PDF

Abstract

GNAO1 mutated in pediatric encephalopathies encodes the major neuronal G-protein Gαo. Of >80 pathogenic mutations, most are single amino acid substitutions spreading across Gαo sequence. We perform extensive characterization of Gαo mutants showing abnormal GTP uptake and hydrolysis, and deficiencies to bind Gβγ and RGS19. Plasma membrane localization of Gαo is decreased for a subset of mutations that leads to epilepsy; dominant interactions with GPCRs also emerge for the more severe mutants. Pathogenic mutants massively gain interaction with Ric8A and, surprisingly, Ric8B proteins, delocalizing them from cytoplasm to Golgi. Of these two mandatory Gα-subunit chaperones, Ric8A is normally responsible for the Gαi/o, Gαq, and Gα12/13 subfamilies, and Ric8B solely for Gαs/olf. Ric8A/B mediate the disease dominance when engaging in neomorphic interactions with pathogenic Gαo through disbalancing the neuronal G protein signaling networks. As the strength of Gαo-Ric8B interactions correlates with disease severity, our study further identifies an efficient biomarker and predictor for clinical manifestations in GNAO1 encephalopathies. Our work discovers the neomorphic molecular mechanism of mutations underlying pediatric encephalopathies and offers insights to other maladies caused by G protein misfunctioning and further genetic diseases.

Authors

Gonzalo P. Solis, Alexey Koval, Jana Valnohova, Arghavan Kazemzadeh, Mikhail Savitsky, Vladimir L. Katanaev

Exclusion of sulfide:quinone oxidoreductase from mitochondria causes Leigh-like disease in mice by impairing sulfide metabolism

• Text
• PDF

Abstract

Leigh syndrome is the most common inherited mitochondrial disease in children and is often fatal within the first few years of life. In 2020, mutations in the gene encoding sulfide:quinone oxidoreductase (SQOR), a mitochondrial protein, were identified as a cause of Leigh syndrome. Here, we report that mice with a mutation in the gene encoding SQOR (SqorΔN/ΔN mice), which prevented SQOR from entering mitochondria, had clinical and pathological manifestations of Leigh syndrome. SqorΔN/ΔN mice had increased blood lactate levels that were associated with markedly decreased complex IV activity and increased hydrogens sulfide (H2S) levels. Because H2S is produced by both gut microbiota and host tissue, we tested whether metronidazole (a broad-spectrum antibiotic) or a sulfur-restricted diet rescues SqorΔN/ΔN mice from developing Leigh syndrome. Daily treatment with metronidazole alleviated increased H2S levels, normalized complex IV activity and blood lactate levels, and prolonged the survival of SqorΔN/ΔN mice. Similarly, a sulfur-restricted diet normalized blood lactate levels and inhibited the development of Leigh syndrome. Taken together, these observations suggest that mitochondrial SQOR is essential to prevent systemic accumulation of H2S. Administration of metronidazole or a sulfur-restricted diet may be therapeutic approaches to treatment of patients with Leigh syndrome caused by mutations in SQOR.

Authors

Eiki Kanemaru, Kakeru Shimoda, Eizo Marutani, Masanobu Morita, Maria Miranda, Yusuke Miyazaki, Claire Sinow, Rohit Sharma, Fangcong Dong, Donald B. Bloch, Takaaki Akaike, Fumito Ichinose

C16ORF70/Mytho promotes healthy ageing in C. elegans and prevents cellular senescence in mammals

• Text
• PDF

Abstract

The identification of genes that confer either extension of lifespan or accelerate age-related decline was a step forward in understanding the mechanisms of ageing and revealed that it is partially controlled by genetics and transcriptional programs. Here we discovered that the human DNA sequence C16ORF70 encoded for a protein, named MYTHO (Macroautophagy and YouTH Optimizer), which controls life- and health-span. MYTHO protein is conserved from C. elegans to humans and its mRNA was upregulated in aged mice and elderly people. Deletion of the ortholog myt-1 gene in C. elegans dramatically shortened lifespan and decreased animal survival upon exposure to oxidative stress. Mechanistically, MYTHO is required for autophagy likely because it acts as a scaffold that binds WIPI2 and BCAS3 to recruit and assemble the conjugation system at the phagophore, the nascent autophagosome. We conclude that MYTHO is a transcriptionally regulated initiator of autophagy that is central in promoting stress resistance and healthy ageing.

Authors

Anais Franco-Romero, Valeria Morbidoni, Giulia Milan, Roberta Sartori, Jesper Wulff, Vanina Romanello, Andrea Armani, Leonardo Salviati, Maria Conte, Stefano Salvioli, Claudio Franceschi, Viviana Buonomo, Casey O. Swoboda, Paolo Grumati, Luca Pannone, Simone Martinelli, Harold B.J. Jefferies, Ivan Dikic, Jennifer van der Laan, Filipe Cabreiro, Douglas P. Millay, Sharon A. Tooze, Eva Trevisson, Marco Sandri

Neutrophil glucose flux as a therapeutic target in antiphospholipid syndrome

• Text
• PDF

Abstract

Neutrophil hyperactivity and neutrophil extracellular trap release (NETosis) appear to play important roles in the pathogenesis of the thromboinflammatory autoimmune disease known as antiphospholipid syndrome (APS). The understanding of neutrophil metabolism has advanced tremendously in the past decade, and accumulating evidence suggests that a variety of metabolic pathways guide neutrophil activities in health and disease. Our previous work characterizing the transcriptome of APS neutrophils revealed that genes related to glycolysis, glycogenolysis, and the pentose phosphate pathway (PPP) were significantly upregulated. Here, we found that APS patient neutrophils used glycolysis more avidly than healthy control neutrophils, especially when the neutrophils were from APS patients with a history of microvascular disease. In vitro, inhibiting either glycolysis or the PPP tempered phorbol myristate acetate- and APS IgG-induced NETosis, but not NETosis triggered by a calcium ionophore. In mice, inhibiting either glycolysis or the PPP reduced neutrophil reactive oxygen species production and suppressed APS IgG-induced NETosis ex vivo. When APS-associated thrombosis was evaluated in mice, inhibiting either glycolysis or the PPP markedly suppressed thrombosis and circulating NET remnants. In summary, these data identify a potential role for restraining neutrophil glucose flux in the treatment of APS.

Authors

Ajay Tambralli, Alyssa Harbaugh, Somanathapura K. NaveenKumar, Megan D. Radyk, Christine E. Rysenga, Kaitlyn Sabb, Julia M. Hurley, Gautam J. Sule, Srilakshmi Yalavarthi, Shanea K. Estes, Claire Hoy, Tristin Smith, Cyrus Sarosh, Jacqueline A. Madison, Jordan K. Schaefer, Suman L. Sood, Yu Zuo, Amr H. Sawalha, Costas A. Lyssiotis, Jason S. Knight

An attenuated lymphocytic choriomeningitis virus vector enhances tumor control in mice partly via IFN-I

• Text
• PDF

Abstract

Viral vectors are being used for the treatment of cancer. Yet their efficacy varies among tumors and their use poses challenges in immunosuppressed patients, underscoring the need for alternatives. We report striking antitumoral effects by a nonlytic viral vector based on attenuated lymphocytic choriomeningitis virus (r3LCMV). We show in multiple tumor models that injection of tumor-bearing mice with this vector results in improved tumor control and survival. Importantly, r3LCMV improved tumor control in immunodeficient Rag1–/– mice and MyD88–/– mice, suggesting that multiple pathways contributed to the antitumoral effects. The antitumoral effects of r3LCMV were also observed when this vector was administered several weeks before tumor challenges, suggesting the induction of trained immunity. Single cell RNA-Seq analyses, antibody blockade experiments, and KO models revealed a critical role for host-intrinsic IFN-I in the antitumoral efficacy of r3LCMV vectors. Collectively, these data demonstrate potent antitumoral effects by r3LCMV vectors and unveil multiple mechanisms underlying their antitumoral efficacy.

Authors

Young Rock Chung, Bakare Awakoaiye, Tanushree Dangi, Nahid Irani, Slim Fourati, Pablo Penaloza-MacMaster