Research Article
Abstract
Normal-tension glaucoma (NTG) is a heterogeneous disease characterized by retinal ganglion cell (RGC) death leading to cupping of the optic nerve head and visual field loss at normal intraocular pressure (IOP). The pathogenesis of NTG remains unclear. Here, we describe a single nucleotide mutation in exon 2 of the methyltransferase-like 23 (METTL23) gene identified in 3 generations of a Japanese family with NTG. This mutation caused METTL23 mRNA aberrant splicing, which abolished normal protein production and altered subcellular localization. Mettl23–knock-in (Mettl23+/G and Mettl23G/G) and -knockout (Mettl23+/– and Mettl23–/–) mice developed a glaucoma phenotype without elevated IOP. METTL23 is a histone arginine methyltransferase expressed in murine and macaque RGCs. However, the novel mutation reduced METTL23 expression in RGCs of Mettl23G/G mice, which recapitulated both clinical and biological phenotypes. Moreover, our findings demonstrated that METTL23 catalyzed the dimethylation of H3R17 in the retina and was required for the transcription of pS2, an estrogen receptor α target gene that was critical for RGC homeostasis through the negative regulation of NF-κB–mediated TNF-α and IL-1β feedback. These findings suggest an etiologic role of METTL23 in NTG with tissue-specific pathology.
Authors
Yang Pan, Akiko Suga, Itaru Kimura, Chojiro Kimura, Yuriko Minegishi, Mao Nakayama, Kazutoshi Yoshitake, Daisuke Iejima, Naoko Minematsu, Megumi Yamamoto, Fumihiko Mabuchi, Mitsuko Takamoto, Yukihiro Shiga, Makoto Araie, Kenji Kashiwagi, Makoto Aihara, Toru Nakazawa, Takeshi Iwata
Abstract
SAMD9 and SAMD9L germline mutations have recently emerged as a new class of predispositions to pediatric myeloid neoplasms. Patients commonly have impaired hematopoiesis, hypocellular marrows, and a greater risk of developing clonal chromosome 7 deletions leading to MDS and AML. We recently demonstrated that expressing SAMD9 or SAMD9L mutations in hematopoietic cells suppresses their proliferation and induces cell death. Here, we generated a mouse model that conditionally expresses mutant Samd9l to assess the in vivo impact on hematopoiesis. Using a range of in vivo and ex vivo assays, we showed that cells with heterozygous Samd9l mutations have impaired stemness relative to wild-type counterparts, which was exacerbated by inflammatory stimuli, and ultimately led to bone marrow hypocellularity. Genomic and phenotypic analyses recapitulated many of the hematopoietic cellular phenotypes observed in patients with SAMD9 or SAMD9L mutations, including lymphopenia, and pinpointed TGF-β as a potential targetable pathway. Further, we observed nonrandom genetic deletion of the mutant Samd9l locus on mouse chromosome 6, mimicking chromosome 7 deletions observed in patients. Collectively, our study has enhanced our understanding of mutant Samd9l hematopoietic phenotypes, emphasized the synergistic role of inflammation in exaggerating the associated hematopoietic defects, and provided insights into potential therapeutic options for patients.
Authors
Sherif Abdelhamed, Melvin E. Thomas III, Tamara Westover, Masayuki Umeda, Emily Xiong, Chandra Rolle, Michael P. Walsh, Huiyun Wu, Jason R. Schwartz, Virginia Valentine, Marcus Valentine, Stanley Pounds, Jing Ma, Laura J. Janke, Jeffery M. Klco
Abstract
The stomach corpus epithelium is organized into anatomical units that consist of glands and pits. Mechanisms that control the cellular organization of corpus glands and enable their recovery upon injury are not well understood. R-spondin 3 (RSPO3) is a WNT-signaling enhancer that regulates stem cell behavior in different organs. Here, we investigated the function of RSPO3 in the corpus during homeostasis, upon chief and/or parietal cell loss, and during chronic Helicobacter pylori infection. Using organoid culture and conditional mouse models, we demonstrate that RSPO3 is a critical driver of secretory cell differentiation in the corpus gland toward parietal and chief cells, while its absence promoted pit cell differentiation. Acute loss of chief and parietal cells induced by high dose tamoxifen — or merely the depletion of LGR5+ chief cells — caused an upregulation of RSPO3 expression, which was required for the initiation of a coordinated regenerative response via the activation of yes-associated protein (YAP) signaling. This response enabled a rapid recovery of the injured secretory gland cells. However, in the context of chronic H. pylori infection, the R-spondin–driven regeneration was maintained long term, promoting severe glandular hyperproliferation and the development of premalignant metaplasia.
Authors
Anne-Sophie Fischer, Stefanie Müllerke, Alexander Arnold, Julian Heuberger, Hilmar Berger, Manqiang Lin, Hans-Joachim Mollenkopf, Jonas Wizenty, David Horst, Frank Tacke, Michael Sigal
Abstract
Abdominal aortic aneurysm (AAA) is a life-threatening vascular disease. BAF60c, a unique subunit of the SWItch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex, is critical for cardiac and skeletal myogenesis, yet little is known about its function in the vasculature and, specifically, in AAA pathogenesis. Here, we found that BAF60c was downregulated in human and mouse AAA tissues, with primary staining to vascular smooth muscle cells (VSMCs), confirmed by single-cell RNA-sequencing. In vivo studies revealed that VSMC-specific knockout of Baf60c significantly aggravated both angiotensin II– (Ang II–) and elastase-induced AAA formation in mice, with a significant increase in elastin degradation, inflammatory cell infiltration, VSMC phenotypic switch, and apoptosis. In vitro studies showed that BAF60c knockdown in VSMCs resulted in loss of contractile phenotype, increased VSMC inflammation, and apoptosis. Mechanistically, we demonstrated that BAF60c preserved VSMC contractile phenotype by strengthening serum response factor (SRF) association with its coactivator P300 and the SWI/SNF complex and suppressing VSMC inflammation by promoting a repressive chromatin state of NF-κB target genes as well as preventing VSMC apoptosis through transcriptional activation of KLF5-dependent B cell lymphoma 2 (BCL2) expression. Our identification of the essential role of BAF60c in preserving VSMC homeostasis expands its therapeutic potential in preventing and treating AAA.
Authors
Guizhen Zhao, Yang Zhao, Haocheng Lu, Ziyi Chang, Hongyu Liu, Huilun Wang, Wenying Liang, Yuhao Liu, Tianqing Zhu, Oren Rom, Yanhong Guo, Lin Chang, Bo Yang, Minerva T. Garcia-Barrio, Jiandie D. Lin, Y. Eugene Chen, Jifeng Zhang
Abstract
The molecular mechanisms underlying obesity-induced increases in β cell mass and the resulting β cell dysfunction need to be elucidated further. Our study revealed that GPR92, expressed in islet macrophages, is modulated by dietary interventions in metabolic tissues. Therefore, we aimed to define the role of GPR92 in islet inflammation by using a high-fat diet–induced (HFD-induced) obese mouse model. GPR92-KO mice exhibited glucose intolerance and reduced insulin levels — despite the enlarged pancreatic islets — as well as increased islet macrophage content and inflammation level compared with WT mice. These results indicate that the lack of GPR92 in islet macrophages can cause β cell dysfunction, leading to disrupted glucose homeostasis. Alternatively, stimulation with the GPR92 agonist farnesyl pyrophosphate results in the inhibition of HFD-induced islet inflammation and increased insulin secretion in WT mice, but not in GPR92-KO mice. Thus, our study suggests that GPR92 can be a potential target to alleviate β cell dysfunction via the inhibition of islet inflammation associated with the progression of diabetes.
Authors
Camila O. de Souza, Vivian A. Paschoal, Xuenan Sun, Lavanya Vishvanath, Qianbin Zhang, Mengle Shao, Toshiharu Onodera, Shiuhwei Chen, Nolwenn Joffin, Lorena M.A. Bueno, Rana K. Gupta, Da Young Oh
Abstract
An effective adaptive immune response depends on the organized architecture of secondary lymphoid organs, including the lymph nodes (LNs). While the cellular composition and microanatomy of LNs under steady state are well defined, the impact of chronic tissue inflammation on the structure and function of draining LNs is incompletely understood. Here we showed that Mycobacterium tuberculosis infection remodeled LN architecture by increasing the number and paracortical translocation of B cells. The formation of paracortical B lymphocyte and CD35+ follicular dendritic cell clusters dispersed CCL21-producing fibroblastic reticular cells and segregated pathogen-containing myeloid cells from antigen-specific CD4+ T cells. Depletion of B cells restored the chemokine and lymphoid structure and reduced bacterial burdens in LNs of the chronically infected mice. Importantly, this remodeling process impaired activation of naive CD4+ T cells in response to mycobacterial and unrelated antigens during chronic tuberculosis infection. Our studies reveal a mechanism in the regulation of LN microanatomy during inflammation and identify B cells as a critical element limiting the T cell response to persistent intracellular infection in LNs.
Authors
Lina Daniel, Nayan D. Bhattacharyya, Claudio Counoupas, Yi Cai, Xinchun Chen, James A. Triccas, Warwick J. Britton, Carl G. Feng
Abstract
Accidental injury to the cardiac conduction system (CCS), a network of specialized cells embedded within the heart and indistinguishable from the surrounding heart muscle tissue, is a major complication in cardiac surgeries. Here, we addressed this unmet need by engineering targeted antibody-dye conjugates directed against the CCS, allowing for the visualization of the CCS in vivo following a single intravenous injection in mice. These optical imaging tools showed high sensitivity, specificity, and resolution, with no adverse effects on CCS function. Further, with the goal of creating a viable prototype for human use, we generated a fully human monoclonal Fab that similarly targets the CCS with high specificity. We demonstrate that, when conjugated to an alternative cargo, this Fab can also be used to modulate CCS biology in vivo, providing a proof of principle for targeted cardiac therapeutics. Finally, in performing differential gene expression analyses of the entire murine CCS at single-cell resolution, we uncovered and validated a suite of additional cell surface markers that can be used to molecularly target the distinct subcomponents of the CCS, each prone to distinct life-threatening arrhythmias. These findings lay the foundation for translational approaches targeting the CCS for visualization and therapy in cardiothoracic surgery, cardiac imaging, and arrhythmia management.
Authors
William R. Goodyer, Benjamin M. Beyersdorf, Lauren Duan, Nynke S. van den Berg, Sruthi Mantri, Francisco X. Galdos, Nazan Puluca, Jan W. Buikema, Soah Lee, Darren Salmi, Elise R. Robinson, Stephan Rogalla, Dillon P. Cogan, Chaitan Khosla, Eben L. Rosenthal, Sean M. Wu
IL-20RB mediates tumoral response to osteoclastic niches and promotes bone metastasis of lung cancer
Abstract
Bone is a common site of metastasis in lung cancer, but the regulatory mechanism remains incompletely understood. Osteoclasts are known to play crucial roles in osteolytic bone metastasis by digesting bone matrix and indirectly enhancing tumor colonization. In this study, we found that IL receptor 20 subunit β (IL-20RB) mediated a direct tumoral response to osteoclasts. Tumoral expression of IL-20RB was associated with bone metastasis of lung cancer, and functionally, IL-20RB promoted metastatic growth of lung cancer cells in bone. Mechanistically, tumor cells induced osteoclasts to secrete the IL-20RB ligand IL-19, and IL-19 stimulated IL-20RB–expressing tumor cells to activate downstream JAK1/STAT3 signaling, leading to enhanced proliferation of tumor cells in bone. Importantly, blocking IL-20RB with a neutralizing antibody significantly suppressed bone metastasis of lung cancer. Overall, our data revealed a direct protumor role of osteoclastic niche in bone metastasis and supported IL-20RB–targeting approaches for metastasis treatment.
Authors
Yunfei He, Wenqian Luo, Yingjie Liu, Yuan Wang, Chengxin Ma, Qiuyao Wu, Pu Tian, Dasa He, Zhenchang Jia, Xianzhe Lv, Yu-Shui Ma, Haitang Yang, Ke Xu, Xue Zhang, Yansen Xiao, Peiyuan Zhang, Yajun Liang, Da Fu, Feng Yao, Guohong Hu
Abstract
Invasive bacterial infections remain a major cause of human morbidity. Group B streptococcus (GBS) are Gram-positive bacteria that cause invasive infections in humans. Here, we show that factor XIIIA–deficient (FXIIIA-deficient) female mice exhibited significantly increased susceptibility to GBS infections. Additionally, female WT mice had increased levels of FXIIIA and were more resistant to GBS infection compared with isogenic male mice. We observed that administration of exogenous FXIIIA to male mice increased host resistance to GBS infection. Conversely, administration of a FXIIIA transglutaminase inhibitor to female mice decreased host resistance to GBS infection. Interestingly, male gonadectomized mice exhibited decreased sensitivity to GBS infection, suggesting a role for gonadal androgens in host susceptibility. FXIIIA promoted GBS entrapment within fibrin clots by crosslinking fibronectin with ScpB, a fibronectin-binding GBS surface protein. Thus, ScpB-deficient GBS exhibited decreased entrapment within fibrin clots in vitro and increased dissemination during systemic infections. Finally, using mice in which FXIIIA expression was depleted in mast cells, we observed that mast cell–derived FXIIIA contributes to host defense against GBS infection. Our studies provide insights into the effects of sexual dimorphism and mast cells on FXIIIA expression and its interactions with GBS adhesins that mediate bacterial dissemination and pathogenesis.
Authors
Adrian M. Piliponsky, Kavita Sharma, Phoenicia Quach, Alyssa Brokaw, Shayla Nguyen, Austyn Orvis, Siddhartha S. Saha, Nyssa Becker Samanas, Ravin Seepersaud, Yu Ping Tang, Emily Mackey, Gauri Bhise, Claire Gendrin, Anna Furuta, Albert J. Seo, Eric Guga, Irina Miralda, Michelle Coleman, Erin L. Sweeney, Charlotte A. Bäuml, Diana Imhof, Jessica M. Snyder, Adam J. Moeser, Lakshmi Rajagopal
Abstract
To understand how kidney donation leads to an increased risk of preeclampsia, we studied pregnant outbred mice with prior uninephrectomy and compared them with sham-operated littermates carrying both kidneys. During pregnancy, uninephrectomized (UNx) mice failed to achieve a physiological increase in the glomerular filtration rate and during late gestation developed hypertension, albuminuria, glomerular endothelial damage, and excess placental production of soluble fms–like tyrosine kinase 1 (sFLT1), an antiangiogenic protein implicated in the pathogenesis of preeclampsia. Maternal hypertension in UNx mice was associated with low plasma volumes, an increased rate of fetal resorption, impaired spiral artery remodeling, and placental ischemia. To evaluate potential mechanisms, we studied plasma metabolite changes using mass spectrometry and noted that l-kynurenine, a metabolite of l-tryptophan, was upregulated approximately 3-fold during pregnancy when compared with prepregnant concentrations in the same animals, consistent with prior reports suggesting a protective role for l-kynurenine in placental health. However, UNx mice failed to show upregulation of l-kynurenine during pregnancy; furthermore, when UNx mice were fed l-kynurenine in drinking water throughout pregnancy, their preeclampsia-like state was rescued, including a reversal of placental ischemia and normalization of sFLT1 levels. In aggregate, we provide a mechanistic basis for how impaired renal reserve and the resulting failure to upregulate l-kynurenine during pregnancy can lead to impaired placentation, placental hypoperfusion, an antiangiogenic state, and subsequent preeclampsia.
Authors
Vincent Dupont, Anders H. Berg, Michifumi Yamashita, Chengqun Huang, Ambart E. Covarrubias, Shafat Ali, Aleksandr Stotland, Jennifer E. Van Eyk, Belinda Jim, Ravi Thadhani, S. Ananth Karumanchi
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ISSN: 0021-9738 (print), 1558-8238 (online)