Accumulation of amyloid-β (Aβ) protein may cause synapse degeneration and cognitive impairment in Alzheimer’s disease (AD) by reactivating expression of the developmental synapse repressor protein Ephexin5 (also known as ARHGEF15). Here, we have reported that Aβ is sufficient to acutely promote the production of Ephexin5 in mature hippocampal neurons and in mice expressing human amyloid precursor protein (hAPP mice), a model for familial AD that produces high brain levels of Aβ. Ephexin5 expression was highly elevated in the hippocampi of human AD patients, indicating its potential relevance to AD. We also observed elevated Ephexin5 expression in the hippocampi of hAPP mice. Removal of Ephexin5 expression eliminated hippocampal dendritic spine loss and rescued AD-associated behavioral deficits in the hAPP mice. Furthermore, selective reduction of Ephexin5 expression using shRNA in the dentate gyrus of presymptomatic adolescent hAPP mice was sufficient to protect these mice from developing cognitive impairment. Thus, pathological elevation of Ephexin5 expression critically drives Aβ-induced memory impairment, and strategies aimed at reducing Ephexin5 levels may represent an effective approach to treating AD.
Gabrielle L. Sell, Thomas B. Schaffer, Seth S. Margolis
Diseases caused by gene haploinsufficiency in humans commonly lack a phenotype in mice that are heterozygous for the orthologous factor, impeding the study of complex phenotypes and critically limiting the discovery of therapeutics. Laboratory mice have longer telomeres relative to humans, potentially protecting against age-related disease caused by haploinsufficiency. Here, we demonstrate that telomere shortening in NOTCH1-haploinsufficient mice is sufficient to elicit age-dependent cardiovascular disease involving premature calcification of the aortic valve, a phenotype that closely mimics human disease caused by NOTCH1 haploinsufficiency. Furthermore, progressive telomere shortening correlated with severity of disease, causing cardiac valve and septal disease in the neonate that was similar to the range of valve disease observed within human families. Genes that were dysregulated due to NOTCH1 haploinsufficiency in mice with shortened telomeres were concordant with proosteoblast and proinflammatory gene network alterations in human NOTCH1 heterozygous endothelial cells. These dysregulated genes were enriched for telomere-contacting promoters, suggesting a potential mechanism for telomere-dependent regulation of homeostatic gene expression. These findings reveal a critical role for telomere length in a mouse model of age-dependent human disease and provide an in vivo model in which to test therapeutic candidates targeting the progression of aortic valve disease.
Christina V. Theodoris, Foteini Mourkioti, Yu Huang, Sanjeev S. Ranade, Lei Liu, Helen M. Blau, Deepak Srivastava
Dowling-Degos disease (DDD) is an autosomal-dominant disorder of skin pigmentation associated with mutations in keratin 5 (
Damian J. Ralser, F. Buket Ü. Basmanav, Aylar Tafazzoli, Jade Wititsuwannakul, Sarah Delker, Sumita Danda, Holger Thiele, Sabrina Wolf, Michélle Busch, Susanne A. Pulimood, Janine Altmüller, Peter Nürnberg, Didier Lacombe, Uwe Hillen, Jörg Wenzel, Jorge Frank, Benjamin Odermatt, Regina C. Betz
Pain is fundamentally unpleasant and induces a negative affective state. The affective component of pain is mediated by circuits that are distinct from those mediating the sensory-discriminative component. Here, we have investigated the role of prostaglandins in the affective dimension of pain using a rodent pain assay based on conditioned place aversion to formalin injection, an inflammatory noxious stimulus. We found that place aversion induced by inflammatory pain depends on prostaglandin E2 that is synthesized by cyclooxygenase 2 in neural cells. Further, mice lacking the prostaglandin E2 receptor EP3 selectively on serotonergic cells or selectively in the area of the dorsal raphe nucleus failed to form an aversion to formalin-induced pain, as did mice lacking the serotonin transporter. Chemogenetic manipulations revealed that EP3 receptor activation elicited conditioned place aversion to pain via inhibition of serotonergic neurons. In contrast to their role in inflammatory pain aversion, EP3 receptors on serotonergic cells were dispensable for acute nociceptive behaviors and for aversion induced by thermal pain or a κ opioid receptor agonist. Collectively, our findings show that prostaglandin-mediated modulation of serotonergic transmission controls the affective component of inflammatory pain.
Anand Kumar Singh, Joanna Zajdel, Elahe Mirrasekhian, Nader Almoosawi, Isabell Frisch, Anna M. Klawonn, Maarit Jaarola, Michael Fritz, David Engblom
Primary myelofibrosis (PMF) is a clonal hematologic malignancy characterized by BM fibrosis, extramedullary hematopoiesis, circulating CD34+ cells, splenomegaly, and a propensity to evolve to acute myeloid leukemia. Moreover, the spleen and BM of patients harbor atypical, clustered megakaryocytes, which contribute to the disease by secreting profibrotic cytokines. Here, we have revealed that megakaryocytes in PMF show impaired maturation that is associated with reduced GATA1 protein. In investigating the cause of GATA1 downregulation, our gene-expression study revealed the presence of the
Laure Gilles, Ahmet Dirim Arslan, Christian Marinaccio, Qiang Jeremy Wen, Priyanka Arya, Maureen McNulty, Qiong Yang, Jonathan C. Zhao, Katerina Konstantinoff, Terra Lasho, Animesh Pardanani, Brady Stein, Isabelle Plo, Sriram Sundaravel, Amittha Wickrema, Annarita Migliaccio, Sandeep Gurbuxani, William Vainchenker, Leonidas C. Platanias, Ayalew Tefferi, John D. Crispino
Germline coding mutations in different telomere-related genes have been linked to autosomal-dominant familial pulmonary fibrosis. Individuals with these inherited mutations demonstrate incomplete penetrance of clinical phenotypes affecting the lung, blood, liver, skin, and other organs. Here, we describe the somatic acquisition of promoter mutations in telomerase reverse transcriptase (
Lindley Maryoung, Yangbo Yue, Ashley Young, Chad A. Newton, Cindy Barba, Nicolai S. C. van Oers, Richard C. Wang, Christine Kim Garcia
Current strategies for HIV-1 eradication require the reactivation of latent HIV-1 in resting CD4+ T cells (rCD4s). Global T cell activation is a well-characterized means of inducing HIV-1 transcription, but is considered too toxic for clinical applications. Here, we have explored a strategy that involves a combination of immune activation and the immunosuppressive mTOR inhibitor rapamycin. In purified rCD4s from HIV-1–infected individuals on antiretroviral therapy, rapamycin treatment downregulated markers of toxicity, including proinflammatory cytokine release and cellular proliferation that were induced after potent T cell activation using αCD3/αCD28 antibodies. Using an ex vivo assay for HIV-1 mRNA, we demonstrated that despite this immunomodulatory effect, rapamycin did not affect HIV-1 gene expression induced by T cell activation in these rCD4s. In contrast, treating activated rCD4s with the immunosuppressant cyclosporin, a calcineurin inhibitor, robustly inhibited HIV-1 reactivation. Importantly, rapamycin treatment did not impair cytotoxic T lymphocyte (CTL) recognition and killing of infected cells. These findings raise the possibility of using rapamycin in conjunction with T cell–activating agents in HIV-1 cure strategies.
Alyssa R. Martin, Ross A. Pollack, Adam Capoferri, Richard F. Ambinder, Christine M. Durand, Robert F. Siliciano
The BM niche comprises a tightly controlled microenvironment formed by specific tissue and cells that regulates the behavior of hematopoietic stem cells (HSCs). Here, we have provided a 3D model that is tunable in different BM niche components and useful, both in vitro and in vivo, for studying the maintenance of normal and malignant hematopoiesis. Using scaffolds, we tested the capacity of different stromal cell types to support human HSCs. Scaffolds coated with human mesenchymal stromal cells (hMSCs) proved to be superior in terms of HSC engraftment and long-term maintenance when implanted in vivo. Moreover, we found that hMSC-coated scaffolds can be modulated to form humanized bone tissue, which was also able to support human HSC engraftment. Importantly, hMSC-coated humanized scaffolds were able to support the growth of leukemia patient cells in vivo, including the growth of samples that would not engraft the BM of immunodeficient mice. These results demonstrate that an s.c. implantation approach in a 3D carrier scaffold seeded with stromal cells is an effective in vivo niche model for studying human hematopoiesis. The various niche components of this model can be changed depending on the context to improve the engraftment of nonengrafting acute myeloid leukemia (AML) samples.
Ander Abarrategi, Katie Foster, Ashley Hamilton, Syed A. Mian, Diana Passaro, John Gribben, Ghulam Mufti, Dominique Bonnet
Atherothrombotic vascular disease is often triggered by a distinct type of atherosclerotic lesion that displays features of impaired inflammation resolution, notably a necrotic core and thinning of a protective fibrous cap that overlies the core. A key cause of plaque necrosis is defective clearance of apoptotic cells, or efferocytosis, by lesional macrophages, but the mechanisms underlying defective efferocytosis and its possible links to impaired resolution in atherosclerosis are incompletely understood. Here, we provide evidence that proteolytic cleavage of the macrophage efferocytosis receptor c-Mer tyrosine kinase (MerTK) reduces efferocytosis and promotes plaque necrosis and defective resolution. In human carotid plaques, MerTK cleavage correlated with plaque necrosis and the presence of ischemic symptoms. Moreover, in fat-fed LDL receptor–deficient (
Bishuang Cai, Edward B. Thorp, Amanda C. Doran, Brian E. Sansbury, Mat J.A.P. Daemen, Bernhard Dorweiler, Matthew Spite, Gabrielle Fredman, Ira Tabas
Stroke is one of the most common diseases and a leading cause of death and disability. Cessation of cerebral blood flow (CBF) leads to cell death in the infarct core, but tissue surrounding the core has the potential to recover if local reductions in CBF are restored. In these areas, detrimental peri-infarct depolarizations (PIDs) contribute to secondary infarct growth and negatively affect stroke outcome. However, the cellular pathways underlying PIDs have remained unclear. Here, we have used in vivo multiphoton microscopy, laser speckle imaging of CBF, and electrophysiological recordings in a mouse model of focal ischemia to demonstrate that PIDs are associated with a strong increase of intracellular calcium in astrocytes and neurons. We found that astroglial calcium elevations during PIDs are mediated by inositol triphosphate receptor type 2–dependent (IP3R2-dependent) release from internal stores. Importantly,
Cordula Rakers, Gabor C. Petzold
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