GPR84-mediated signal transduction effects metabolic function by promoting brown adipocyte activity

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Abstract

The G protein-coupled receptor 84 (GPR84), a medium-chain fatty acid receptor, has garnered attention because of its potential involvement in a range of metabolic conditions. However, the precise mechanisms underlying this effect remain elusive. Our study has shed light on the pivotal role of GPR84, revealing its robust expression and functional significance within the brown adipose tissue (BAT). Mice lacking GPR84 exhibited increased lipid accumulation in BAT, rendering them more susceptible to cold exposure, and displaying reduced BAT activity compared to their wild-type counterparts. Our in vitro experiments with primary brown adipocytes from GPR84 knockout mice revealed diminished expression of thermogenic genes and reduced O2 consumption. Furthermore, the application of the GPR84 agonist 6-OAU counteracted these effects, effectively reinstating the brown adipocyte activity. These compelling in vivo and in vitro findings converge to highlight mitochondrial dysfunction as the primary cause of BAT anomalies in GPR84 knockout mice. The activation of GPR84 induced an increase in intracellular Ca2+ levels, which intricately influences mitochondrial respiration. By modulating mitochondrial Ca2+ levels and respiration, GPR84 has emerged as a potent molecule involved in BAT activity. These findings suggested that GPR84 is a potential therapeutic target for invigorating BAT and ameliorating metabolic disorders.

Authors

Xuenan Sun, Yu A. An, Vivian A. Paschoal, Camila O. De Souza, May-yun Wang, Lavanya Vishvanath, Lorena M.A. Bueno, Ayanna S. Cobb, Joseph A. Nieto Carrion, Madison E. Ibe, Chao Li, Harrison A. Kidd, Shiuhwei Chen, Wenhong Li, Rana K. Gupta, Da Young Oh

Metixene is an incomplete autophagy inducer in preclinical models of metastatic cancer and brain metastases

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Abstract

A paucity of chemotherapeutic options for metastatic brain cancer limits patient survival and portends poor clinical outcomes. Using a central nervous system (CNS) small-molecule inhibitor library of 320 agents known to be blood-brain barrier permeable and approved by the U.S. Food and Drug Administration, breast cancer brain metastases vulnerabilities were interrogated to identify an effective agent. Metixene, an antiparkinsonian drug, was identified as a top therapeutic agent that was capable of decreasing cellular viability and inducing cell death across different metastatic breast cancer subtypes. This agent significantly reduced mammary tumor size in orthotopic xenograft assays and improved survival in an intracardiac model of multiorgan site metastases. Metixene further extended survival in mice bearing intracranial xenografts and in an intracarotid model of multiple brain metastases. Functional analysis revealed that metixene induced incomplete autophagy through N-Myc Downstream Regulated 1 (NDRG1) phosphorylation thereby leading to caspase-mediated apoptosis in both primary and brain metastatic cells, regardless of cancer subtype or origin. CRISPR Cas9 knockout of NDRG1 led to autophagy completion and reversal of the metixene apoptotic effect. Metixene is a promising therapeutic agent against metastatic brain cancer, with minimal reported side effects in humans, which merits consideration for clinical translation.

Authors

Jawad Fares, Edgar Petrosyan, Deepak Kanojia, Crismita Dmello, Alex Cordero, Joseph T. Duffy, Ragini Yeeravalli, Mayurbhai H. Sahani, Peng Zhang, Aida Rashidi, Victor A. Arrieta, Ilya Ulasov, Atique U. Ahmed, Jason Miska, Irina V. Balyasnikova, C. David James, Adam M. Sonabend, Amy B. Heimberger, Maciej S. Lesniak

Profilin1 is required to prevent mitotic catastrophe in murine and human glomerular diseases

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Abstract

The progression of proteinuric kidney diseases is associated with podocyte loss but the mechanisms underlying this process remain unclear. Podocytes re-enter the cell cycle to repair double-stranded DNA (dsDNA) breaks. However, the unsuccessful repair can result in podocytes crossing the G1/S checkpoint and undergoing abortive cytokinesis. In this study, we identified Pfn1 as indispensable in maintaining glomerular integrity - its tissue-specific loss in mouse podocytes results in severe proteinuria and kidney failure. Our results suggest that this phenotype is due to podocyte mitotic catastrophe (MC), characterized histologically and ultrastructurally by abundant multinucleated cells, irregular nuclei, and mitotic spindles. Podocyte cell cycle re-entry was identified using FUCCI2aR mice and observed altered expression of cell-cycle associated proteins such as p21, p53, Cyclin B1, and Cyclin D1. Podocyte-specific translating ribosome affinity purification (TRAP) and RNAseq revealed the downregulation of Ribosomal RNA-processing protein 8 (Rrp8). Over-expression of Rrp8 in Pfn1 KO podocytes partially rescued the phenotype in vitro. Clinical and ultrastructural tomographic analysis of patients with diverse proteinuric kidney diseases further validated the presence of MC podocytes and reduction in podocyte PFN1 expression within kidney tissues. These results suggest that profilin1 is essential in regulating the podocyte cell cycle and its disruption leads to MC and subsequent podocyte loss.

Authors

Xuefei Tian, Christopher E. Pedigo, Ke Li, Xiaotao Ma, Patricia Bunda, John Pell, Angela Lek, Jianlei Gu, Yan Zhang, Paulina X. Medina Rangel, Wei Li, Eike Schwartze, Soichiro Nagata, Gabriel Lerner, Sudhir Perincheri, Anupama Priyadarshini, Hongyu Zhao, Monkol Lek, Madhav C. Menon, Rongguo Fu, Shuta Ishibe

A gain-of-function p53 mutant synergizes with oncogenic NRAS to promote acute myeloid leukemia in mice

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Abstract

We previously demonstrated that a subset of acute myeloid leukemia (AML) patients with concurrent RAS pathway and TP53 mutations have extremely poor prognosis, and most of these TP53 mutations are missense mutations. Here, we report that in contrast to mixed AML and T-cell malignancy developed in NrasG12D/+; p53-/- (NP-/-) mice, NrasG12D/+; p53R172H/+ (NPmut) mice rapidly developed an inflammation-associated AML. Under the inflammatory conditions, NPmut hematopoietic stem and progenitor cells (HSPCs) displayed imbalanced myelopoiesis and lymphopoiesis and largely normal cell proliferation despite MEK/ERK hyperactivation. RNA-Seq analysis revealed that oncogenic NRAS signaling and mutant p53 synergize to establish an NPmut-AML transcriptome distinct from that of NP-/- cells. The NPmut-AML transcriptome showed GATA2 downregulation and elevated expression of inflammatory genes, including those linked to NFκB signaling. NFκB was also upregulated in human NRAS;TP53 AML. Exogenous expression of GATA2 in human NPmut KY821 AML cells downregulated inflammatory gene expression. Mouse and human NPmut AML cells were sensitive to MEK and NFκB inhibition in vitro. The proteasome inhibitor bortezomib stabilized NFκB inhibitory protein IκBα reduced inflammatory gene expression, and potentiated the survival benefit of a MEK inhibitor in NPmut mice. Our study demonstrates that a p53 structural mutant synergizes with oncogenic NRAS to promote AML through mechanisms distinct from p53 loss.

Authors

Adhithi Rajagopalan, Yubin Feng, Meher B. Gayatri, Erik A. Ranheim, Taylor Klungness, Daniel R. Matson, Moon Hee Lee, Mabel Minji Jung, Yun Zhou, Xin Gao, Kalyan V.G. Nadiminti, David T. Yang, Vu L. Tran, Eric Padron, Shigeki Miyamoto, Emery H. Bresnick, Jing Zhang

A brain–tumor neural circuit controls breast cancer progression in mice

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Abstract

Tumor burden, considered a common chronic stressor, can cause widespread anxiety. Evidence suggests that cancer-induced anxiety can promote tumor progression, but the underlying neural mechanism remains unclear. Here, we used neuroscience and cancer tools to investigate how the brain contributes to tumor progression via nerve-tumor crosstalk in mice model of breast cancer. We showed that the tumor-bearing mice exhibited significant anxiety-like behaviors and that corticotropin-releasing hormone (CRH) neurons in the central medial amygdala (CeM) were activated. Moreover, newly formed sympathetic nerves were detected in tumors, which established a polysynaptically connected with the brain. Pharmacogenetic or optogenetic inhibition of CeMCRH neurons and CeMCRH→LPGi circuit significantly alleviated anxiety-like behaviors and slowed tumor growth. Conversely, artificial activation of CeMCRH neurons and CeMCRH→LPGi circuit increased anxiety and tumor growth. Importantly, alprazolam, an anti-anxiety drug, was found to be a promising intervention for slowing tumor progression. Furthermore, we showed that manipulation of CeMCRH→LPGi circuit directly regulates the activity of the intratumoral sympathetic nerves and peripheral nerve-derived norepinephrine, then affecting tumor progression by modulating the antitumor immunity. Together, these findings reveal a brain–tumor neural circuit contributing to breast cancer progression and provide new therapeutic insights for breast cancer.

Authors

Si-Yi Xiong, Hui-Zhong Wen, Li-Meng Dai, Yun-Xiao Lou, Zhao-Qun Wang, Yi-Lun Yi, Xiao-Jing Yan, Ya-Ran Wu, Wei Sun, Peng-Hui Chen, Si-Zhe Yang, Xiao-Wei Qi, Yi Zhang, Guang-Yan Wu

OSR1 disruption contributes to uterine factor infertility via impaired Müllerian duct development and endometrial receptivity

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Abstract

Three sisters, born from consanguineous parents, manifested a unique Mullerian anomaly characterized by uterine hypoplasia with thin estrogen-unresponsive endometrium, primary amenorrhea, but spontaneous tubal pregnancies. Through whole-exome sequencing followed by comprehensive genetic analysis, a missense variant was identified in the OSR1 gene. We therefore investigated OSR1/OSR1 expression in postpubertal human uteri, and the prenatal and postnatal expression pattern of Osr1/Osr1 in murine developing Mullerian ducts (MDs) and endometrium, respectively. We then investigated whether Osr1 deletion would affect MD development, using wild-type and genetically engineered mice. Human uterine OSR1/OSR1 expression was found primarily in the endometrium. Mouse Osr1 was expressed prenatally in MDs and Wolffian ducts (WDs), from rostral to caudal segments, in E13.5 embryos. MDs and WDs were absent on the left side and MDs were rostrally truncated on the right side of E13.5 Osr1-/- embryos. Postnatally, Osr1 was expressed in mouse uteri throughout lifespan, peaking at postnatal days 14 and 28. Osr1 protein was present primarily in uterine luminal and glandular epithelial cells and in the epithelial cells of mouse oviducts. Through this translational approach, we demonstrated that OSR1/Osr1 is important for MD development and endometrial receptivity and may be implicated in uterine factor infertility.

Authors

Adriana Lofrano-Porto, Sidney Alcântara Pereira, Andrew Dauber, Jordana C.B. Bloom, Audrey N. Fontes, Naomi Asimow, Olívia Laquis de Moraes, Petra Ariadne T. Araujo, Ana Paula Abreu, Michael H. Guo, Silviene F. De Oliveira, Han Liu, Charles Lee, Wendy Kuohung, Michella S. Coelho, Rona S. Carroll, Rulang Jiang, Ursula B. Kaiser

Hypertriglyceridemia in Apoa5^–/– mice results from reduced amounts of lipoprotein lipase in the capillary lumen

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Abstract

Why apolipoprotein AV (APOA5) deficiency causes hypertriglyceridemia has remained unclear, but we suspected that the underlying cause was reduced amounts of lipoprotein lipase (LPL) in capillaries. By routine immunohistochemistry, we observed reduced LPL staining of heart and brown adipose tissue (BAT) capillaries in Apoa5–/– mice. Also, after an intravenous injection of LPL-, CD31-, and GPIHBP1-specific monoclonal antibodies, the binding of LPL antibodies to heart and BAT capillaries (relative to CD31 or GPIHBP1 antibodies) was reduced in Apoa5–/– mice. LPL levels in the postheparin plasma were also lower in Apoa5–/– mice. We suspected that a recent biochemical observation—that APOA5 binds to the ANGPTL3/8 complex and suppresses its capacity to inhibit LPL catalytic activity—could be related to the low intracapillary LPL levels in Apoa5–/– mice. We showed that an ANGPTL3/8-specific monoclonal antibody (IBA490) and APOA5 normalize plasma triglyceride levels and intracapillary LPL levels in Apoa5–/– mice. We also showed that ANGPTL3/8 detaches LPL from HSPGs and GPIHBP1 on the surface of cells and that the LPL detachment is blocked by IBA490 and APOA5. Our studies explain the hypertriglyceridemia in Apoa5–/– mice and further illuminate the molecular mechanisms that regulate plasma triglyceride metabolism.

Authors

Ye Yang, Anne P. Beigneux, Wenxin Song, Le Phuong Nguyen, Hyesoo Jung, Yiping Tu, Thomas A. Weston, Caitlyn M. Tran, Katherine Xie, Rachel G. Yu, Anh P. Tran, Kazuya Miyashita, Katsuyuki Nakajima, Masami Murakami, Yan Q. Chen, Eugene Y. Zhen, Joonyoung R. Kim, Paul H. Kim, Gabriel Birrane, Peter Tontonoz, Michael Ploug, Robert J. Konrad, Loren G. Fong, Stephen G. Young

Endothelial lipid droplets suppress eNOS to link high fat consumption to blood pressure elevation

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Abstract

The metabolic syndrome, today affecting more than 20% of the US population, is a group of five conditions that often co-exist and that strongly predispose to cardiovascular disease. How these conditions are linked mechanistically remains unclear, especially two of these: obesity and elevated blood pressure. Here we show that high fat consumption in mice leads to the accumulation of lipid droplets in endothelial cells throughout the organism, and that lipid droplet accumulation in endothelium suppresses endothelial nitric oxide synthase (eNOS), reduces NO production, elevates blood pressure, and accelerates atherosclerosis. Mechanistically, the accumulation of lipid droplets destabilizes eNOS mRNA and activates an endothelial inflammatory signaling cascade that suppresses eNOS and NO production. Pharmacological prevention of lipid droplet formation reverses the suppression of NO production in cell culture and in vivo, and blunts blood pressure elevation in response to high fat diet. These results highlight lipid droplets as a critical and unappreciated component of endothelial cell biology, explain how lipids increase blood pressure acutely, and provide a mechanistic account for the epidemiological link between obesity and elevated blood pressure.

Authors

Boa Kim, Wencao Zhao, Soon Yew Tang, Michael G. Levin, Ayon Ibrahim, Yifan Yang, Emilia M. Roberts, Ling Lai, Jian Li, Richard K. Assoian, Garret A. FitzGerald, Zoltan Arany

Improving radiotherapy in immunosuppressive microenvironments by targeting complement receptor C5aR1

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Abstract

An immunosuppressive microenvironment causes poor tumour T-cell infiltration and is associated with reduced patient overall survival in colorectal cancer. How to improve treatment responses in these tumours is still a challenge. Using an integrated screening approach to identify cancer-specific vulnerabilities, we identified complement receptor C5aR1 as a druggable target which when inhibited improved radiotherapy even in tumours displaying immunosuppressive features and poor CD8+ T-cell infiltration. While C5aR1 is well-known for its role in the immune compartment, we found that C5aR1 is also robustly expressed on malignant epithelial cells, highlighting potential tumour-cell specific functions. C5aR1 targeting resulted in increased NF-kB-dependent apoptosis specifically in tumours and not normal tissues; indicating that in malignant cells, C5aR1 primarily regulated cell fate. Collectively, these data revealed that increased complement gene expression is part of the stress response mounted by irradiated tumours and that targeting C5aR1 could improve radiotherapy even in tumours displaying immunosuppressive features.

Authors

Callum Beach, David MacLean, Dominika Majorova, Stavros Melemenidis, Dhanya K. Nambiar, Ryan K. Kim, Gabriel N. Valbuena, Silvia Guglietta, Carsten Krieg, Mahnaz Darvish-Damavandi, Tatsuya Suwa, Alistair Easton, Lily V.S. Hillson, Ashley K. McCulloch, Ross K. McMahon, Kathryn Pennel, Joanne Edwards, Sean M. O’Cathail, Campbell S. Roxburgh, Enric Domingo, Eui Jung Moon, Dadi Jiang, Yanyan Jiang, Qingyang Zhang, Albert C. Koong, Trent M. Woodruff, Edward E. Graves, Tim Maughan, Simon J.A. Buczacki, Manuel Stucki, Quynh Thu Le, Simon J. Leedham, Amato J. Giaccia, Monica M. Olcina

Claudin-2 protects from colitis-associated cancer by promoting colitis-associated mucosal healing

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Abstract

Inflammatory bowel disease (IBD) patients are susceptible to colitis-associated cancer (CAC). Chronic inflammation promotes the risk for CAC. In contrast, mucosal healing predicts improved prognosis in IBD and reduced risk of CAC. However, molecular integration between colitis, mucosal healing and CAC remains poorly understood. Claudin-2 (CLDN2) expression is upregulated in IBD, however, its role in CAC is not known. The current study was undertaken to examine the role for CLDN2 in CAC. The AOM/DSS-induced CAC model was used with wild type (WT), and CLDN2 modified mice. High-throughput expression analyses, murine models of colitis/recovery, chronic colitis, ex-vivo crypt culture and pharmacological manipulations were employed for mechanistic understanding. The Cldn2KO mice showed significant inhibition of CAC despite severe colitis compared to WT-littermates. Cldn2 loss also resulted in impaired recovery from colitis and increased injury when subjected to intestinal injury by other methods. Mechanistic studies demonstrated a novel role of CLDN2 in promoting mucosal healing downstream of EGFR-signaling and by regulating Survivin expression. An upregulated CLDN2 expression protected from CAC and associated positively with crypt regeneration and Survivin expression in IBD patients. We demonstrate a novel role of CLDN2 in promoting mucosal healing in IBD patients, and thus regulating vulnerability to colitis severity and CAC, which can be exploited for improved clinical management.

Authors

Rizwan Ahmad, Balawant Kumar, Ishwor Thapa, Raju Lama Tamang, Santosh Kumar Yadav, Mary K. Washington, Geoffrey A. Talmon, Alan S. Yu, Dhundy K. Bastola, Punita Dhawan, Amar B. Singh