Schwannomas are tumors of the Schwann cells that cause chronic pain, numbness, and potentially life-threatening impairment of vital organs. Despite the identification of causative genes including NF2 (Merlin), INI1/SMARCB1, and LZTR1, the exact molecular mechanism of schwannoma development is still poorly understood. Several studies have identified Merlin as a key regulator of the Hippo, MAPK, and PI3K signaling pathways, however definitive evidence demonstrating the importance of these pathways in schwannoma pathogenesis is absent. Here, we provide direct genetic evidence that dysregulation of the Hippo pathway in the Schwann cell lineage causes development of multiple Schwannomas in mice. We found that canonical Hippo signaling through the effectors YAP/TAZ is required for schwannomagenesis and that MAPK signaling modifies schwannoma formation. Furthermore, co-targeting YAP/TAZ transcriptional activity and MAPK signaling demonstrated a synergistic therapeutic effect on schwannoma. Our new model provides a tractable platform to dissect the molecular mechanisms underpinning schwannoma formation and the role of combinatorial targeted therapy in schwannoma treatment.
Zhiguo Chen, Stephen Li, Juan Mo, Eric T. Hawley, Yong Wang, Yongzheng He, Jean-Philippe Brosseau, Tracey Shipman, D. Wade Clapp, Thomas J. Carroll, Lu Q. Le
Giant cell arteritis (GCA) is a common form of primary systemic vasculitis in adults with no reliable indicators of prognosis or treatment responses. We used single cell technologies to comprehensively map immune cell populations in the blood of patients with GCA and identified the CD66b+CD15+CD10lo/-CD64- band neutrophils and CD66bhiCD15+CD10lo/-CD64+/bright myelocytes/metamyelocytes to be unequivocally associated with both the clinical phenotype and response to treatment. Immature neutrophils were resistant to apoptosis, remained in the vasculature for a prolonged time, interacted with platelets, and extravasated into the tissue surrounding the temporal arteries of patients with GCA. We discovered that immature neutrophils generated high levels of extracellular reactive oxygen species, leading to enhanced protein oxidation and permeability of endothelial barrier in an in vitro co-culture system. The same populations were also detected in other systemic vasculitides. These findings link functions of immature neutrophils to disease pathogenesis, establishing a new clinical cellular signature of GCA and suggesting new therapeutic approaches in systemic vascular inflammation.
Lihui Wang, Zhichao Ai, Tariq E. Khoyratty, Kristina Zec, Hayley L. Eames, Erinke van Grinsven, Alison Hudak, Susan Morris, David J. Ahern, Claudia Monaco, Evgeniy B. Eruslanov, Raashid Luqmani, Irina A. Udalova
We determined that renal proximal tubular (PT) NFκB essential modulator (NEMO) plays a direct and critical role in ischemic acute kidney injury (AKI) utilizing using mice lacking renal PT NEMO and by targeted renal PT NEMO inhibition with mesoscale nanoparticle encapsulated NEMO binding peptide (MNP NBP). We subjected renal PT NEMO deficient mice, wild type (WT) mice and C57BL/6 mice to sham surgery or 30 min renal ischemia and reperfusion (IR). C57BL/6 mice received NBP MNP or empty MNP before renal IR injury. Mice treated with MNP NBP and mice deficient in renal PT NEMO were protected against ischemic AKI with decreased renal tubular necrosis, inflammation and apoptosis compared to control MNP treated or WT mice, respectively. Recombinant peptidylarginine deiminase type-4 (rPAD4) targets kidney PT NEMO to exacerbate ischemic AKI as exogenous rPAD4 exacerbated renal IR injury in WT mice but not in renal proximal tubule NEMO deficient mice. Furthermore, rPAD4 upregulated proinflammatory cytokine mRNA and NFκB activation in freshly isolated renal proximal tubules from WT mice but not from PT NEMO deficient mice. Taken together, our studies suggest that renal PT NEMO plays a critical role in ischemic AKI by promoting renal tubular inflammation, apoptosis as well as necrosis.
Sang Jun Han, Ryan M. williams, Mihwa Kim, Daniel A. Heller, Vivette D'Agati, Marc Schmidt-Supprian, H. Thomas Lee
Fibrosis is the final common pathway in the pathophysiology of most forms of chronic kidney disease (CKD). As treatment of renal fibrosis still remains largely supportive, a refined understanding of the cellular and molecular mechanisms of kidney fibrosis and the development of novel compounds are urgently needed. Whether arginases play a role in development of fibrosis in CKD is unclear. We hypothesize that endothelial-arginase-2 (Arg2) promotes the development of kidney fibrosis induced by unilateral ureteral obstruction (UUO). Arg2 expression and arginase activity significantly increased following renal fibrosis. Pharmacological blockade or genetic deficiency of Arg2 conferred kidney protection following renal fibrosis as reflected by a reduction in kidney interstitial fibrosis and fibrotic markers. Selective deletion of Arg2 in endothelial cells (Tie2Cre/Arg2flox/flox) reduced the level of fibrosis after UUO. In contrast, selective deletion of Arg2 specifically in proximal tubular cells (Ggt1Cre/Arg2flox/flox) failed to reduce renal fibrosis after UUO. Furthermore, arginase inhibition restored kidney nitric oxide (NO) levels, oxidative stress, and mitochondrial function following UUO.These findings indicate that endothelial-Arg2 plays a major role in renal fibrosis via its action on NO and mitochondrial function. Blocking Arg2 activity or expression could be a novel therapeutic approach for prevention of CKD.
Michael Wetzel, Kristen Stanley, Wei Wei Wang, Soumya Maity, Muniswamy Madesh, W. Brian Reeves, Alaa S. Awad
A critical response to lysosomal membrane permeabilization (LMP) is the clearance of damaged lysosomes through a selective form of macroautophagy known as lysophagy. Although regulators of this process are emerging, whether organ and cell specific components contribute to the control of lysophagy remains incompletely understood. Here, we examine LMP and lysophagy in Niemann-Pick type C disease (NPC), an autosomal recessive disorder characterized by the accumulation of unesterified cholesterol within late endosomes and lysosomes, leading to neurodegeneration and early death. We demonstrate that NPC patient fibroblasts show enhanced sensitivity to lysosomal damage as a consequence of lipid storage. Moreover, we describe a role for the glycan binding F-box protein Fbxo2 in CNS lysophagy. Fbxo2 functions as a component of the SCF ubiquitin ligase complex. Loss of Fbxo2 in mouse primary cortical cultures delays clearance of damaged lysosomes and decreases viability following lysosomal damage. Moreover, Fbxo2 deficiency in a mouse model of NPC exacerbates deficits in motor function, enhances neurodegeneration, and reduces survival. Collectively, our data identify a role for Fbxo2 in CNS lysophagy and establish its functional importance in NPC.
Elaine A. Liu, Mark L. Schultz, Chisaki Mochida, Chan Chung, Henry L. Paulson, Andrew P. Lieberman
Dilated cardiomyopathy (DCM) is often associated with sarcomere protein mutations that confer reduced myofilament tension-generating capacity. We demonstrate that cardiac twitch tension-time integrals can be targeted and tuned to prevent DCM remodeling in hearts with contractile dysfunction. We employ a transgenic murine model of DCM caused by the D230N tropomyosin (Tm) mutation and design a sarcomere-based intervention specifically targeting the twitch tension-time integral of D230N-Tm hearts using multiscale computational models of intra- and inter-molecular interactions in the thin filament and cell-level contractile simulations. Our models predict that increasing the calcium-sensitivity of thin filament activation using the cardiac troponin C (cTnC) variant L48Q can sufficiently augment twitch tension-time integrals of D230N-Tm hearts. Indeed, cardiac muscle isolated from double-transgenic (DTG) hearts expressing D230N Tm and L48Q cTnC have increased calcium-sensitivity of tension development and increased twitch tension-time integrals compared to preparations from hearts with D230N Tm alone. Longitudinal echocardiographic measurements revealed that DTG hearts retain normal cardiac morphology and function, while D230N-Tm hearts develop progressive DCM. We present a computational and experimental framework for targeting molecular mechanisms governing the twitch tension of cardiomyopathic hearts to counteract putative mechanical drivers of adverse remodeling, and open new possibilities for tension-based treatments of genetic cardiomyopathies.
Joseph D. Powers, Kristina B. Kooiker, Allison B. Mason, Abigail E. Teitgen, Galina V. Flint, Jil C. Tardiff, Steven D. Schwartz, Andrew D. McCulloch, Michael Regnier, Jennifer Davis, Farid Moussavi-Harami
Impaired tolerance to innocuous particles during allergic asthma has been linked to the increased plasticity of FoxP3+ regulatory T (Treg) cells, reprogramming into pathogenic effector cells, thus exacerbating airway disease. Failure in tolerance is suggested to be driven by TH2 inflammatory signals. The canonical IL-4Rα-signalling, an essential driver of TH2-type airway responses to allergens was investigated on its in vivo role on the regulatory function of FoxP3+ Tregs in allergic asthma. We used transgenic Foxp3creIL-4rα-/lox and littermate control mice to investigate the role of IL-4/IL-13 signalling via T regs in a house dust mite (HDM)-induced allergic airway disease. We sensitised mice intratracheally on day 0 and challenged them on day 6-10 and analysed airway hyperresponsiveness (AHR), airway inflammation, mucus production and cellular profile on day 14. In the absence of IL-4Rα responsiveness on FoxP3+ Tregs, there was an exacerbated AHR and airway inflammation in HDM-sensitised mice. Interestingly, a reduced induction of FoxP3+ Tregs accompanied increased IL-33 “alarmin” production and innate lymphoid cells type 2 (ILC2) activation in the lung exacerbating airway hyperreactivity and lung eosinophilia. We conclude that IL-4Rα unresponsive FoxP3+ T regulatory cells results in exaggerated innate TH2-type, IL-33-dependent airway inflammation and a break in tolerance during allergic asthma.
Jermaine Khumalo, Frank Kirstein, Sabelo Hadebe, Frank Brombacher
Ischemia-reperfusion-induced edema (IRE) one of the most significant causes of mortality after lung transplantation can be mimicked ex-vivo in isolated perfused mouse lungs (IPL). Transient receptor potential vanilloid 4 (TRPV4) is a non-selective cation channel studied in endothelium, while its role in the lung epithelium remains elusive. Here we show enhanced IRE in TRPV4-deficient (TRPV4–/–) IPL compared to wild-type (WT) controls, indicating a protective role of TRPV4 to maintain the alveolar epithelial barrier. By immunohistochemistry, mRNA profiling and electrophysiological characterization, we detected TRPV4 in bronchial epithelium, alveolar type I (ATI) and alveolar type II (ATII) cells. Genetic ablation of TRPV4 resulted in reduced expression of the water conducting aquaporin-5 (AQP-5) channel in ATI cells. Migration of TRPV4–/– ATI cells was reduced and cell barrier function was impaired. Analysis of isolated primary TRPV4-deficient ATII cells revealed a reduced expression of surfactant protein C (SP-C) and the TRPV4 activator GSK1016790A induced increases in current densities only in WT ATII cells. Moreover, TRPV4–/– lungs of adult mice developed significantly larger mean chord lengths and altered lung function compared to WT lungs. Therefore, our data discover essential functions of TRPV4 channels in alveolar epithelial cells and in the protection from edema formation.
Jonas Weber, Suhasini Rajan, Christian Schremmer, Yu-Kai Chao, Gabriela Krasteva-Christ, Martina Kannler, Ali Önder Yildirim, Monika Brosien, Johann Schredelseker, Norbert Weissmann, Christian Grimm, Thomas Gudermann, Alexander Dietrich
In the aging population, lower urinary tract (LUT) dysfunction is common and often leads to storage and voiding difficulties classified into overlapping symptom syndromes. Despite prevalence and consequences of these syndromes, LUT disorders continue to be undertreated simply because there are few therapeutic options. LUT function and structure were assessed in aged (>25 months) male and female Fischer 344 rats randomized to oral treatment with a purine nucleoside phosphorylase (PNPase inhibitor) 8-aminoguanine (8-AG) for 6 weeks or vehicle. The bladders of aged rats exhibited multiple abnormalities: tactile insensitivity, vascular remodeling, reduced collagen-fiber tortuosity, increased bladder stiffness, abnormal smooth muscle morphology, swelling of mitochondria and increases in uro-damaging purine metabolites. Treatment of aged rats with 8-AG restored all evaluated histological, ultrastructural and physiological abnormalities toward that of a younger state. 8-AG, is an effective treatment that ameliorates key age-related structural and physiologic bladder abnormalities. Because PNPase inhibition blocks metabolism of inosine to hypoxanthine and guanosine to guanine, likely uro-protective effects of 8-AG are mediated by increased bladder levels of uro-protective inosine and guanosine and reductions in uro-damaging hypoxanthine and xanthine. These findings demonstrate 8-AG has translational potential for treating age-associated LUT dysfunctions and resultant syndromes in humans.
Lori A. Birder, Amanda Wolf-Johnston, Alan J. Wein, Fangzhou Cheng, Mara Grove-Sullivan, Anthony J. Kanai, Alan M. Watson, Donna Stolz, Simon C. Watkins, Anne M. Robertson, Diane Newman, Roger R. Dmochowski, Edwin K. Jackson
Focal adhesion kinase (FAK) is an important mediator of extracellular matrix-integrin mechano-signal transduction that regulates cell motility, survival, and proliferation. As such, FAK is being investigated as a potential therapeutic target for malignant and fibrotic diseases, and numerous clinical trials of FAK inhibitors are underway. The function of FAK in non-malignant non-motile epithelial cells is not well understood. We previously showed that hepatocytes demonstrated activated FAK near stiff collagen tracts in fibrotic liver. In this study, we examined the role of liver epithelial FAK by inducing fibrotic liver disease in mice with liver epithelial FAK deficiency. We found that mice that lack FAK in liver epithelial cells develop more severe liver injury and worse fibrosis as compared to controls. Increased fibrosis in liver epithelial FAK-deficient mice is linked to the activation of several pro-fibrotic pathways, including the hedgehog-smoothened pathway. FAK-deficient hepatocytes produce increased Indian hedgehog in a manner dependent on matrix stiffness. Furthermore, expression of the hedgehog receptor, smoothened, is increased in macrophages and biliary cells of hepatocyte-specific FAK-deficient fibrotic liver. These results indicate that liver epithelial FAK has important regulatory roles in the response to liver injury and progression of fibrosis.
Yun Weng, Tyler J. Lieberthal, Vivian X. Zhou, Maya Lopez-Ichikawa, Manuel Armas-Phan, Tristan K. Bond, Miya C. Yoshida, Won-Tak Choi, Tammy T. Chang
No posts were found with this tag.