TERT mutations may make smokers more susceptible to emphysema: Coverage by News-Medical.net and Lung Cancer News Today on “Telomerase mutations in smokers with severe emphysema.”
Possible new treatment for hypothyroidism: Coverage by News-Medical.net and the People's Pharmacy on “Differences in hypothalamic type 2 deiodinase ubiquitination explain localized sensitivity to thyroxine.”
T cell identification brings cure for type 1 diabetes closer: Coverage by Diabetes.co.uk on “Follicular helper T cell signature in type 1 diabetes.”
Lung fibrosis risk in elderly: Coverage by Pulmonary Hypertension News on “PINK1 deficiency impairs mitochondrial homeostasis and promotes lung fibrosis.”
Obesity and glucose intake: Coverage by Newsweek on “Glucokinase activity in the arcuate nucleus regulates glucose intake.”
Mitigating gene therapy risk: Coverage by Genetic Engineering & Biotechnology News and NIH on “Vector design influences hepatic genotoxicity after adeno-associated virus gene therapy.”
New lung cancer drug target: Coverage by Science blog on “Pyruvate carboxylase is critical for non–small-cell lung cancer proliferation.”
Blocking receptor counters Alzheimers: Coverage by Stanford Med and Inquisitir.com on “Prostaglandin signaling suppresses beneficial microglial function in Alzheimer’s disease models.”
Ghrelin hormone and infant obesity: Coverage by Medical Daily and Healthline on “Neonatal ghrelin programs development of hypothalamic feeding circuits.”
Cellular mechanism protects lungs during severe infections: Coverage by Digital Journal, Medical News Today and Infection Control Today on “HIF2α signaling inhibits adherens junctional disruption in acute lung injury.”
Mutations in the essential telomerase genes
Susan E. Stanley, Julian J.L. Chen, Joshua D. Podlevsky, Jonathan K. Alder, Nadia N. Hansel, Rasika A. Mathias, Xiaodong Qi, Nicholas M. Rafaels, Robert A. Wise, Edwin K. Silverman, Kathleen C. Barnes, Mary Armanios
The current treatment for patients with hypothyroidism is levothyroxine (L-T4) along with normalization of serum thyroid-stimulating hormone (TSH). However, normalization of serum TSH with L-T4 monotherapy results in relatively low serum 3,5,3′-triiodothyronine (T3) and high serum thyroxine/T3 (T4/T3) ratio. In the hypothalamus-pituitary dyad as well as the rest of the brain, the majority of T3 present is generated locally by T4 deiodination via the type 2 deiodinase (D2); this pathway is self-limited by ubiquitination of D2 by the ubiquitin ligase WSB-1. Here, we determined that tissue-specific differences in D2 ubiquitination account for the high T4/T3 serum ratio in adult thyroidectomized (Tx) rats chronically implanted with subcutaneous L-T4 pellets. While L-T4 administration decreased whole-body D2-dependent T4 conversion to T3, D2 activity in the hypothalamus was only minimally affected by L-T4. In vivo studies in mice harboring an astrocyte-specific
Joao Pedro Werneck de Castro, Tatiana L. Fonseca, Cintia B. Ueta, Elizabeth A. McAninch, Sherine Abdalla, Gabor Wittmann, Ronald M. Lechan, Balazs Gereben, Antonio C. Bianco
The strong genetic association between particular HLA alleles and type 1 diabetes (T1D) indicates a key role for CD4+ T cells in disease; however, the differentiation state of the responsible T cells is unclear. T cell differentiation originally was considered a dichotomy between Th1 and Th2 cells, with Th1 cells deemed culpable for autoimmune islet destruction. Now, multiple additional T cell differentiation fates are recognized with distinct roles. Here, we used a transgenic mouse model of diabetes to probe the gene expression profile of islet-specific T cells by microarray and identified a clear follicular helper T (Tfh) cell differentiation signature. Introduction of T cells with a Tfh cell phenotype from diabetic animals efficiently transferred diabetes to recipient animals. Furthermore, memory T cells from patients with T1D expressed elevated levels of Tfh cell markers, including
Rupert Kenefeck, Chun Jing Wang, Tauseef Kapadi, Lukasz Wardzinski, Kesley Attridge, Louise E. Clough, Frank Heuts, Alexandros Kogimtzis, Sapna Patel, Miranda Rosenthal, Masahiro Ono, David M. Sansom, Parth Narendran, Lucy S.K. Walker
Although aging is a known risk factor for idiopathic pulmonary fibrosis (IPF), the pathogenic mechanisms that underlie the effects of advancing age remain largely unexplained. Some age-related neurodegenerative diseases have an etiology that is related to mitochondrial dysfunction. Here, we found that alveolar type II cells (AECIIs) in the lungs of IPF patients exhibit marked accumulation of dysmorphic and dysfunctional mitochondria. These mitochondrial abnormalities in AECIIs of IPF lungs were associated with upregulation of ER stress markers and were recapitulated in normal mice with advancing age in response to stimulation of ER stress. We found that impaired mitochondria in IPF and aging lungs were associated with low expression of PTEN-induced putative kinase 1 (PINK1). Knockdown of PINK1 expression in lung epithelial cells resulted in mitochondria depolarization and expression of profibrotic factors. Moreover, young PINK1-deficient mice developed similarly dysmorphic, dysfunctional mitochondria in the AECIIs and were vulnerable to apoptosis and development of lung fibrosis. Our data indicate that PINK1 deficiency results in swollen, dysfunctional mitochondria and defective mitophagy, and promotes fibrosis in the aging lung.
Marta Bueno, Yen-Chun Lai, Yair Romero, Judith Brands, Claudette M. St. Croix, Christelle Kamga, Catherine Corey, Jose D. Herazo-Maya, John Sembrat, Janet S. Lee, Steve R. Duncan, Mauricio Rojas, Sruti Shiva, Charleen T. Chu, Ana L. Mora
The brain relies on a constant supply of glucose, its primary fuel, for optimal function. A taste-independent mechanism within the CNS that promotes glucose delivery to the brain has been postulated to maintain glucose homeostasis; however, evidence for such a mechanism is lacking. Here, we determined that glucokinase activity within the hypothalamic arcuate nucleus is involved in regulation of dietary glucose intake. In fasted rats, glucokinase activity was specifically increased in the arcuate nucleus but not other regions of the hypothalamus. Moreover, pharmacologic and genetic activation of glucokinase in the arcuate nucleus of rodent models increased glucose ingestion, while decreased arcuate nucleus glucokinase activity reduced glucose intake. Pharmacologic targeting of potential downstream glucokinase effectors revealed that ATP-sensitive potassium channel and P/Q calcium channel activity are required for glucokinase-mediated glucose intake. Additionally, altered glucokinase activity affected release of the orexigenic neurotransmitter neuropeptide Y in response to glucose. Together, our results suggest that glucokinase activity in the arcuate nucleus specifically regulates glucose intake and that appetite for glucose is an important driver of overall food intake. Arcuate nucleus glucokinase activation may represent a CNS mechanism that underlies the oft-described phenomena of the “sweet tooth” and carbohydrate craving.
Syed Hussain, Errol Richardson, Yue Ma, Christopher Holton, Ivan De Backer, Niki Buckley, Waljit Dhillo, Gavin Bewick, Shuai Zhang, David Carling, Steve Bloom, James Gardiner
The use of adeno-associated virus (AAV) as a gene therapy vector has been approved recently for clinical use and has demonstrated efficacy in a growing number of clinical trials. However, the safety of AAV as a vector has been challenged by a single study that documented hepatocellular carcinoma (HCC) after AAV gene delivery in mice. Most studies have not noted genotoxicity following AAV-mediated gene delivery; therefore, the possibility that there is an association between AAV and HCC is controversial. Here, we performed a comprehensive study of HCC in a large number of mice following therapeutic AAV gene delivery. Using a sensitive high-throughput integration site-capture technique and global expressional analysis, we found that AAV integration into the RNA imprinted and accumulated in nucleus (
Randy J. Chandler, Matthew C. LaFave, Gaurav K. Varshney, Niraj S. Trivedi, Nuria Carrillo-Carrasco, Julien S. Senac, Weiwei Wu, Victoria Hoffmann, Abdel G. Elkahloun, Shawn M. Burgess, Charles P. Venditti
Anabolic biosynthesis requires precursors supplied by the Krebs cycle, which in turn requires anaplerosis to replenish precursor intermediates. The major anaplerotic sources are pyruvate and glutamine, which require the activity of pyruvate carboxylase (PC) and glutaminase 1 (GLS1), respectively. Due to their rapid proliferation, cancer cells have increased anabolic and energy demands; however, different cancer cell types exhibit differential requirements for PC- and GLS-mediated pathways for anaplerosis and cell proliferation. Here, we infused patients with early-stage non–small-cell lung cancer (NSCLC) with uniformly 13C-labeled glucose before tissue resection and determined that the cancerous tissues in these patients had enhanced PC activity. Freshly resected paired lung tissue slices cultured in 13C6-glucose or 13C5,15N2-glutamine tracers confirmed selective activation of PC over GLS in NSCLC. Compared with noncancerous tissues, PC expression was greatly enhanced in cancerous tissues, whereas GLS1 expression showed no trend. Moreover, immunohistochemical analysis of paired lung tissues showed PC overexpression in cancer cells rather than in stromal cells of tumor tissues. PC knockdown induced multinucleation, decreased cell proliferation and colony formation in human NSCLC cells, and reduced tumor growth in a mouse xenograft model. Growth inhibition was accompanied by perturbed Krebs cycle activity, inhibition of lipid and nucleotide biosynthesis, and altered glutathione homeostasis. These findings indicate that PC-mediated anaplerosis in early-stage NSCLC is required for tumor survival and proliferation.
Katherine Sellers, Matthew P. Fox, Michael Bousamra II, Stephen P. Slone, Richard M. Higashi, Donald M. Miller, Yali Wang, Jun Yan, Mariia O. Yuneva, Rahul Deshpande, Andrew N. Lane, Teresa W.-M. Fan
Microglia, the innate immune cells of the CNS, perform critical inflammatory and noninflammatory functions that maintain normal neural function. For example, microglia clear misfolded proteins, elaborate trophic factors, and regulate and terminate toxic inflammation. In Alzheimer’s disease (AD), however, beneficial microglial functions become impaired, accelerating synaptic and neuronal loss. Better understanding of the molecular mechanisms that contribute to microglial dysfunction is an important objective for identifying potential strategies to delay progression to AD. The inflammatory cyclooxygenase/prostaglandin E2 (COX/PGE2) pathway has been implicated in preclinical AD development, both in human epidemiology studies and in transgenic rodent models of AD. Here, we evaluated murine models that recapitulate microglial responses to Aβ peptides and determined that microglia-specific deletion of the gene encoding the PGE2 receptor EP2 restores microglial chemotaxis and Aβ clearance, suppresses toxic inflammation, increases cytoprotective insulin-like growth factor 1 (IGF1) signaling, and prevents synaptic injury and memory deficits. Our findings indicate that EP2 signaling suppresses beneficial microglia functions that falter during AD development and suggest that inhibition of the COX/PGE2/EP2 immune pathway has potential as a strategy to restore healthy microglial function and prevent progression to AD.
Jenny U. Johansson, Nathaniel S. Woodling, Qian Wang, Maharshi Panchal, Xibin Liang, Angel Trueba-Saiz, Holden D. Brown, Siddhita D. Mhatre, Taylor Loui, Katrin I. Andreasson
A complex neural network regulates body weight and energy balance, and dysfunction in the communication between the gut and this neural network is associated with metabolic diseases, such as obesity. The stomach-derived hormone ghrelin stimulates appetite through interactions with neurons in the arcuate nucleus of the hypothalamus (ARH). Here, we evaluated the physiological and neurobiological contribution of ghrelin during development by specifically blocking ghrelin action during early postnatal development in mice. Ghrelin blockade in neonatal mice resulted in enhanced ARH neural projections and long-term metabolic effects, including increased body weight, visceral fat, and blood glucose levels and decreased leptin sensitivity. In addition, chronic administration of ghrelin during postnatal life impaired the normal development of ARH projections and caused metabolic dysfunction. Consistent with these observations, direct exposure of postnatal ARH neuronal explants to ghrelin blunted axonal growth and blocked the neurotrophic effect of the adipocyte-derived hormone leptin. Moreover, chronic ghrelin exposure in neonatal mice also attenuated leptin-induced STAT3 signaling in ARH neurons. Collectively, these data reveal that ghrelin plays an inhibitory role in the development of hypothalamic neural circuits and suggest that proper expression of ghrelin during neonatal life is pivotal for lifelong metabolic regulation.
Sophie M. Steculorum, Gustav Collden, Berengere Coupe, Sophie Croizier, Sarah Lockie, Zane B. Andrews, Florian Jarosch, Sven Klussmann, Sebastien G. Bouret
Vascular endothelial barrier dysfunction underlies diseases such as acute respiratory distress syndrome (ARDS), characterized by edema and inflammatory cell infiltration. The transcription factor HIF2α is highly expressed in vascular endothelial cells (ECs) and may regulate endothelial barrier function. Here, we analyzed promoter sequences of genes encoding proteins that regulate adherens junction (AJ) integrity and determined that
Haixia Gong, Jalees Rehman, Haiyang Tang, Kishore Wary, Manish Mittal, Pallavi Chatturvedi, Youyang Zhao, Yulia A. Komorova, Stephen M. Vogel, Asrar B. Malik