Haemostasis requires conversion of fibrinogen to fibrin fibres that generate a characteristic network, interact with blood cells, and initiate tissue repair. The fibrin network is porous and highly permeable, but the spatial arrangement of the external clot face is unknown. Here we show that fibrin transitioned to the blood-air interface through Langmuir film formation, producing a protective film confining the clot. We demonstrated that only fibrin is required to form the film, and that it occurred in vitro and in vivo. The fibrin film connected to the underlying clot network through tethering fibres. It was digested by plasmin and formation of the film was prevented with surfactants. Functionally, the film retained blood cells and protected against penetration by bacterial pathogens in a murine model of dermal infection. Our data show a remarkable aspect of blood clotting, in which fibrin forms a protective film covering the external surface of the clot, defending the organism against microbial invasion.
Fraser L. Macrae, Cédric Duval, Praveen Papareddy, Stephen R. Baker, Nadira Yuldasheva, Katherine J. Kearney, Helen R. McPherson, Nathan Asquith, Joke Konings, Alessandro Casini, Jay L. Degen, Simon D. Connell, Helen Philippou, Alisa S. Wolberg, Heiko Herwald, Robert A.S. Ariëns
Receptor tyrosine kinases (RTKs) are important drivers of cancers. In addition to genomic alterations, aberrant activation of wild type RTKs plays an important role in driving cancer progression. However, the underlying mechanisms of how RTKs drive prostate cancer remain incompletely characterized. Here we show that non-proteolytic ubiquitination of RTK regulates its kinase activity and contributes to RTK-mediated prostate cancer metastasis. TRAF4, an E3 ubiquitin ligase, is highly expressed in metastatic prostate cancer. We demonstrated here that it is a key player in regulating RTK mediated prostate cancer metastasis. We further identified TrkA, a neurotrophin RTK, as TRAF4-targeted ubiquitination substrate that promotes cancer cell invasion and inhibition of TrkA activity abolished TRAF4-dependent cell invasion. TRAF4 promoted K27 and K29-linked ubiquitination at the TrkA kinase domain and increased its kinase activity. Mutation of TRAF4-targeted ubiquitination sites abolished TrkA tyrosine auto-phosphorylation and its interaction with downstream proteins. TRAF4 knockdown also suppressed NGF-stimulated TrkA downstream p38 MAPK activation and invasion-associated gene expression. Furthermore, elevated TRAF4 levels significantly correlated with increased NGF-stimulated invasion-associated gene expression in prostate cancer patients, indicating that this signaling axis is significantly activated during oncogenesis. Our results revealed a post-translational modification mechanism contributing to aberrant non-mutated RTK activation in cancer cells.
Ramesh Singh, Dileep Karri, Hong Shen, Jiangyong Shao, Subhamoy Dasgupta, Shixia Huang, Dean P. Edwards, Michael M. Ittmann, Bert W. O’Malley, Ping Yi
For gene therapy of gain-of-function autosomal dominant diseases, either correcting or deleting the disease allele is potentially curative. To test whether there may be an advantage of one approach over the other for WHIM (warts, hypogammaglobulinemia, infections and myelokathexis) syndrome — a primary immunodeficiency disorder caused by gain-of-function autosomal dominant mutations in chemokine receptor CXCR4 — we performed competitive transplantation experiments using both lethally irradiated wild-type (Cxcr4+/+) and unconditioned WHIM (Cxcr4+/w) recipient mice. In both models, hematopoietic reconstitution was markedly superior using bone marrow (BM) cells from donors hemizygous for Cxcr4 (Cxcr4+/o) compared with BM cells from Cxcr4+/+ donors. Remarkably, only ~6% Cxcr4+/o hematopoietic stem cell (HSC) chimerism post-transplantation in unconditioned Cxcr4+/w recipient BM supported >70% long-term donor myeloid chimerism in blood and corrected myeloid cell deficiency in blood. Donor Cxcr4+/o HSCs differentiated normally and did not undergo exhaustion as late as 465 days post-transplantation. Thus, disease allele deletion resulting in Cxcr4 haploinsufficiency was superior to disease allele repair in a mouse model of gene therapy for WHIM syndrome, allowing correction of leukopenia without recipient conditioning.
Ji-Liang Gao, Erin Yim, Marie Siwicki, Alexander Yang, Qian Liu, Ari Azani, Albert Owusu-Ansah, David H. McDermott, Philip M. Murphy
The superoxide-generating enzyme Nox2 contributes to hypertension and cardiovascular remodeling triggered by activation of the renin-angiotensin system. Multiple Nox2-expressing cells are implicated in angiotensin II (AngII)-induced pathophysiology, but the importance of Nox2 in leukocyte subsets is poorly understood. Here, we investigated the role of Nox2 in T cells, particularly Tregs. Mice globally deficient in Nox2 displayed increased numbers of Tregs in the heart at baseline whereas AngII-induced T-effector cell (Teffs) infiltration was inhibited. To investigate the role of Treg Nox2, we generated a mouse line with CD4-targeted Nox2 deficiency (Nox2fl/flCD4Cre+). These animals showed inhibition of AngII-induced hypertension and cardiac remodeling related to increased tissue-resident Tregs and reduction in infiltrating Teffs, including Th17 cells. The protection in Nox2fl/flCD4Cre+ mice was reversed by anti-CD25 Ab-depletion of Tregs. Mechanistically, Nox2–/y Tregs showed higher in vitro suppression of Teffs proliferation than WT Tregs, increased nuclear levels of FoxP3 and NF-κB, and enhanced transcription of CD25, CD39, and CD73. Adoptive transfer of Tregs confirmed that Nox2-deficient cells had greater inhibitory effects on AngII-induced heart remodeling than WT cells. These results identify a previously unrecognized role of Nox2 in modulating suppression of Tregs, which acts to enhance hypertension and cardiac remodeling.
Amber Emmerson, Silvia Cellone Trevelin, Heloise Mongue-Din, Pablo D. Becker, Carla Ortiz, Lesley A. Smyth, Qi Peng, Raul Elgueta, Greta Sawyer, Aleksandar Ivetic, Robert I. Lechler, Giovanna Lombardi, Ajay M. Shah
Spinal muscular atrophy (SMA), a degenerative motor neuron (MN) disease caused by loss of functional SMN protein due to SMN1 gene mutations, is a leading cause of infant mortality. Increasing SMN levels ameliorates the disease phenotype and is unanimously accepted as a therapeutic approach for SMA patients. The ubiquitin/proteasome system is known to regulate SMN protein levels; however whether autophagy controls SMN levels remains poorly explored. Here we show that SMN protein is degraded by autophagy. Pharmacological and genetic inhibition of autophagy increase SMN levels, while induction of autophagy decreases SMN. SMN degradation occurs via its interaction with the autophagy adapter p62/SQSTM1. We also show that SMA neurons display reduced autophagosome clearance, increased p62/ubiquitinated protein levels, and hyperactivated mTORC1 signaling. Importantly, reducing p62 levels markedly increases SMN and its binding partner gemin2, promotes MN survival and extends lifespan in fly and mouse SMA models revealing p62 as a new potential therapeutic target to treat SMA.
Natalia Rodriguez-Muela, Andrey Parkhitko, Tobias Grass, Rebecca M. Gibbs, Erika M. Norabuena, Norbert Perrimon, Rajat Singh, Lee L. Rubin
Progression of chronic kidney disease associated with progressive fibrosis and impaired tubular epithelial regeneration is still an unmet biomedical challenge, because once chronic lesions have manifested, no effective therapies are available as of yet for clinical use. Prompted by various studies across multiple organs demonstrating that preconditioning regimens to induce endogenous regenerative mechanisms protect various organs from later incurring acute injuries, we here aimed to gain insights into the molecular mechanisms underlying successful protection and to explore whether such pathways could be utilized to inhibit progression of chronic organ injury. We identified a protective mechanism that is controlled by the transcription factor ARNT, which effectively inhibits progression of chronic kidney injury by transcriptional induction of ALK3, the principal mediator of anti-fibrotic and pro-regenerative BMP signaling responses. We further report that ARNT expression itself is controlled by the FKBP12/YY1 transcriptional repressor complex, and that disruption of such FKBP12/YY1 complexes by picomolar FK506 at sub-immunosuppressive doses increases ARNT expression, subsequently leading to homodimeric ARNT-induced ALK3 transcription. Direct targeting of FKBP12/YY1 with in vivo-morpholino approaches or small molecule inhibitors including GPI-1046 were equally effective to induce ARNT expression with subsequent activation of ALK3-dependent canonical BMP signaling responses and attenuated chronic organ failure in models of chronic kidney, but also cardiac and liver injuries. In summary, we report an organ protective mechanism, which can be pharmacologically modulated by immunophilin ligands FK506, GPI-1046 or therapeutically targeted by in vivo-morpholino approaches.
Björn Tampe, Désirée Tampe, Gunsmaa Nyamsuren, Friederike Klöpper, Gregor Rapp, Anne Kauffels, Thomas Lorf, Elisabeth M. Zeisberg, Gerhard A. Müller, Raghu Kalluri, Samy Hakroush, Michael Zeisberg
Complications of diabetes affect tissues throughout body, including central nervous system. Epidemiological studies show that diabetic patients have increased risk of depression, anxiety, age-related cognitive decline and Alzheimer’s disease. Mice lacking insulin receptor in brain or on hypothalamic neurons display an array of metabolic abnormalities, however, the role of insulin action on astrocytes and neurobehaviors remains less well-studied. Here, we demonstrate that astrocytes are a direct insulin target in the brain and that knockout of IR on astrocytes causes increased anxiety and depressive-like behaviors in mice. This can be reproduced in part by deletion of IR on astrocytes in the nucleus accumbens. At a molecular level, loss of insulin signaling in astrocytes impaired tyrosine phosphorylation of Munc18c. This led to decreased exocytosis of ATP from astrocytes, resulting in decreased purinergic signaling on dopaminergic neurons. These reductions contributed to decreased dopamine release from brain slices. Central administration of ATP analogues could reverse depressive-like behaviors in mice with astrocyte IR knockout. Thus, astrocytic insulin signaling plays an important role in dopaminergic signaling, providing a potential mechanism by which astrocytic insulin action may contribute to increased rates of depression in people with diabetes, obesity and other insulin resistant states.
Weikang Cai, Chang Xue, Masaji Sakaguchi, Masahiro Konishi, Alireza Shirazian, Heather A. Ferris, Mengyao Li, Ruichao Yu, Andre Kleinridders, Emmanuel N. Pothos, C. Ronald Kahn
Synthetic lethality-based strategy has been developed to identify therapeutic targets in cancer harboring tumor suppressor gene mutations, as exemplified by the effectiveness of PARP inhibitors in BRCA1/2-mutated tumors. However, many synthetic lethal interactors are less reliable due to the fact that such genes usually do not perform fundamental or indispensable functions in the cell. Here we developed an approach to identify the “essential lethality” arose from these mutated/deleted essential genes, which are largely tolerated in cancer cells due to genetic redundancy. We uncovered the cohesion subunit SA1 as a putative synthetic-essential target in cancers carrying inactivating mutations of its paralog, SA2. In SA2-deficient Ewing sarcoma and bladder cancer, further depletion of SA1 profoundly and specifically suppressed cancer cell proliferation, survival and tumorigenic potential. Mechanistically, inhibition of SA1 in the SA2-mutated cells led to premature chromatid separation, dramatic extension of mitotic duration, and consequently lethal failure of cell division. More importantly, depletion of SA1 rendered those SA2-mutated cells more susceptible to DNA damage, especially double-strand breaks (DSBs), due to reduced functionality of DNA repair. Furthermore, inhibition of SA1 sensitized the SA2-deficient cancer cells to PARP inhibitors in vitro and in vivo, providing a potential therapeutic strategy for patients with SA2-deficient tumors.
Yunhua Liu, Hanchen Xu, Kevin Van der Jeught, Yujing Li, Sheng Liu, Lu Zhang, Yuanzhang Fang, Xinna Zhang, Milan Rodovich, Bryan P. Schneider, Xiaoming He, Cheng Huang, Chi Zhang, Jun Wan, Guang Ji, Xiongbin Lu
BACKGROUND. Monogenic Interferon (IFN)-mediated autoinflammatory diseases present in infancy with systemic inflammation, an IFN-response-gene-signature (IRS), inflammatory organ damage and high mortality. We used the janus kinase (JAK) inhibitor baricitinib with IFN-blocking activity in vitro, to ameliorate disease. METHODS. Between October 2011 and February 2017, 10 patients with CANDLE (chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperatures), 4 with SAVI (Stimulator of IFN genes (STING)-associated vasculopathy with onset in infancy), and 4 patients with other interferonopathies were enrolled in an Expanded Access Program. Patients underwent dose-escalation, benefit was assessed by reductions in daily disease symptoms and corticosteroid requirement. Quality-of-life, organ inflammation, changes in IFN-induced biomarkers, and safety were longitudinally assessed. RESULTS. 18 patients were treated for a mean duration of 3.0 years (1.5–4.9 years). The median daily symptom score decreased from 1.3 (IQR 0.93–1.78) to 0.25 (IQR 0.1-0.63) (P < 0.0001). In 14 patients receiving steroids at baseline, daily prednisone doses decreased from 0.44 mg/kg/day (IQR 0.31–1.09) to 0.11 mg/kg/day (IQR 0.02–0.24) (P < 0.01); 5 of 10 CANDLE patients achieved lasting clinical remission. Quality of life, height and bone mineral density Z-scores significantly improved, and IFN biomarkers decreased. Three patients discontinued, two with genetically undefined conditions due to lack of efficacy, and one CANDLE patient due to BK viremia and azotemia. The most common adverse events were upper respiratory infections, gastroenteritis, BK viruria and viremia. CONCLUSION. On baricitinib treatment, clinical manifestations, inflammatory and IFN biomarkers improved in patients with the monogenic interferonopathies, CANDLE, SAVI and 2 other interferonopathies. Monitoring safety and efficacy is important in benefit-risk assessment. TRIAL REGISTRATION. ClinicalTrials.gov NCT01724580 and NCT02974595. FUNDING. NIH, NIAID, NIAMS, NIDDK, NHLBI, NINDS, and the Clinical Center. Baricitinib was provided by Eli Lilly. Eli Lilly is the sponsor of the compassionate use program.
Gina A. Montealegre Sanchez, Adam Reinhardt, Suzanne Ramsey, Helmut Wittkowski, Philip J. Hashkes, Yackov Berkun, Susanne Schalm, Sara Murias, Jason A. Dare, Diane Brown, Deborah L. Stone, Ling Gao, Thomas Klausmeier, Dirk Foell, Adriana A. de Jesus, Dawn C. Chapelle, Hanna Kim, Samantha Dill, Robert Colbert, Laura Failla, Bahar Kost, Michelle O'Brien, James C. Reynolds, Les R. Folio, Katherine R. Calvo, Scott M. Paul, Nargues Weir, Alessandra Brofferio, Ariane Soldatos, Angélique Biancotto, Edward W. Cowen, John G. Digiovanna, Massimo Gadina, Andrew J. Lipton, Colleen Hadigan, Steven M. Holland, Joseph Fontana, Ahmad S. Alawad, Rebecca J. Brown, Kristina I. Rother, Theo Heller, Kristina M. Brooks, Parag Kumar, Stephen R. Brooks, Meryl Waldman, Harsharan K. Singh, Volker Nickeleit, Maria Silk, Apurva Prakash, Jonathan M. Janes, Seza Ozen, Paul G. Wakim, Paul A. Brogan, William L. Macias, Raphaela Goldbach-Mansky
Activation of non-neuronal microglia is thought to play a causal role in spinal processing of neuropathic pain. To specifically investigate microglia-mediated effects in a model of neuropathic pain and overcome methodological limitations of previous approaches exploring microglia function upon nerve injury, we selectively ablated resident microglia by intracerebroventricular (icv) ganciclovir infusion into male CD11b-HSVTK transgenic mice, which was followed by a rapid, complete and persistent (23 weeks) repopulation of the CNS by peripheral myeloid cells. In repopulated mice that underwent sciatic nerve injury, we observed a normal response to mechanical stimuli, but an absence of thermal hypersensitivity ipsilateral to the injured nerve. Furthermore, we found that neuronal expression of calcitonin gene-related peptide (CGRP), which is a marker of neurons essential for heat responses, was diminished in the dorsal horn of the spinal cord in repopulated mice. These findings demonstrate distinct mechanisms for heat and mechanical hypersensitivity, highlighting a crucial contribution of CNS myeloid cells in the facilitation of noxious heat.
Stefanie Kälin, Kelly R. Miller, Roland E. Kälin, Marina Jendrach, Christian Witzel, Frank L. Heppner
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