An increase in hepatic glucose production (HGP) represents a key feature of type 2 diabetes. This deficiency in metabolic control of glucose production critically depends on enhanced signaling through hepatic glucagon receptors (GCGRs). Here, we have demonstrated that selective inactivation of the GPCR-associated protein β-arrestin 2 in hepatocytes of adult mice results in greatly increased hepatic GCGR signaling, leading to striking deficits in glucose homeostasis. However, hepatocyte-specific β-arrestin 2 deficiency did not affect hepatic insulin sensitivity or β-adrenergic signaling. Adult mice lacking β-arrestin 1 selectively in hepatocytes did not show any changes in glucose homeostasis. Importantly, hepatocyte-specific overexpression of β-arrestin 2 greatly reduced hepatic GCGR signaling and protected mice against the metabolic deficits caused by the consumption of a high-fat diet. Our data support the concept that strategies aimed at enhancing hepatic β-arrestin 2 activity could prove useful for suppressing HGP for therapeutic purposes.
Lu Zhu, Mario Rossi, Yinghong Cui, Regina J. Lee, Wataru Sakamoto, Nicole A. Perry, Nikhil M. Urs, Marc G. Caron, Vsevolod V. Gurevich, Grzegorz Godlewski, George Kunos, Minyong Chen, Wei Chen, Jürgen Wess
Huntington’s disease is a neurodegenerative disorder caused by a polyglutamine repeat in the Huntingtin gene (HTT). Although suppressing the expression of mutant HTT (mHTT) has been explored as a therapeutic strategy to treat Huntington’s disease, considerable efforts have gone into developing allele-specific suppression of mHTT expression, given that loss of Htt in mice can lead to embryonic lethality. It remains unknown whether depletion of HTT in the adult brain, regardless of its allele, could be a safe therapy. Here, we report that permanent suppression of endogenous mHTT expression in the striatum of mHTT-expressing mice (HD140Q-knockin mice) using CRISPR/Cas9-mediated inactivation effectively depleted HTT aggregates and attenuated early neuropathology. The reduction of mHTT expression in striatal neuronal cells in adult HD140Q-knockin mice did not affect viability, but alleviated motor deficits. Our studies suggest that non–allele-specific CRISPR/Cas9-mediated gene editing could be used to efficiently and permanently eliminate polyglutamine expansion–mediated neuronal toxicity in the adult brain.
Su Yang, Renbao Chang, Huiming Yang, Ting Zhao, Yan Hong, Ha Eun Kong, Xiaobo Sun, Zhaohui Qin, Peng Jin, Shihua Li, Xiao-Jiang Li
Chronic viral infections are difficult to treat, and new approaches are needed, particularly those aimed at reducing reactivation by enhancing immune responses. Herpes simplex virus (HSV) establishes latency and reactivates frequently, and breakthrough reactivation can occur despite suppressive antiviral therapy. Virus-specific T cells are important to control HSV, and proliferation of activated T cells requires increased metabolism of glutamine. Here, we found that supplementation with oral glutamine reduced virus reactivation in latently HSV-1–infected mice and HSV-2–infected guinea pigs. Transcriptome analysis of trigeminal ganglia from latently HSV-1–infected, glutamine-treated WT mice showed upregulation of several IFN-γ–inducible genes. In contrast to WT mice, supplemental glutamine was ineffective in reducing the rate of HSV-1 reactivation in latently HSV-1–infected IFN-γ–KO mice. Mice treated with glutamine also had higher numbers of HSV-specific IFN-γ–producing CD8 T cells in latently infected ganglia. Thus, glutamine may enhance the IFN-γ–associated immune response and reduce the rate of reactivation of latent virus infection.
Kening Wang, Yo Hoshino, Kennichi Dowdell, Marta Bosch-Marce, Timothy G. Myers, Mayra Sarmiento, Lesley Pesnicak, Philip R. Krause, Jeffrey I. Cohen
Generation of functional hematopoietic stem and progenitor cells (HSPCs) from human pluripotent stem cells (PSCs) has been a long-sought-after goal for use in hematopoietic cell production, disease modeling, and eventually transplantation medicine. Homing of HSPCs from bloodstream to bone marrow (BM) is an important aspect of HSPC biology that has remained unaddressed in efforts to derive functional HSPCs from human PSCs. We have therefore examined the BM homing properties of human induced pluripotent stem cell–derived HSPCs (hiPS-HSPCs). We found that they express molecular effectors of BM extravasation, such as the chemokine receptor CXCR4 and the integrin dimer VLA-4, but lack expression of E-selectin ligands that program HSPC trafficking to BM. To overcome this deficiency, we expressed human fucosyltransferase 6 using modified mRNA. Expression of fucosyltransferase 6 resulted in marked increases in levels of cell surface E-selectin ligands. The glycoengineered cells exhibited enhanced tethering and rolling interactions on E-selectin–bearing endothelium under flow conditions in vitro as well as increased BM trafficking and extravasation when transplanted into mice. However, glycoengineered hiPS-HSPCs did not engraft long-term, indicating that additional functional deficiencies exist in these cells. Our results suggest that strategies toward increasing E-selectin ligand expression could be applicable as part of a multifaceted approach to optimize the production of HSPCs from human PSCs.
Jungmin Lee, Brad Dykstra, Joel A. Spencer, Laurie L. Kenney, Dale L. Greiner, Leonard D. Shultz, Michael A. Brehm, Charles P. Lin, Robert Sackstein, Derrick J. Rossi
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
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