Medicine and Health Sciences Commons^™

Sex-Specific Alterations In Hepatic Cholesterol Metabolism In Low Birth Weight Adult Guinea Pigs., Ousseynou Sarr, Katherine E Mathers, Christina Vanderboor, Kristina Wiggers, Aditya Devgan, Daniel B Hardy, Lin Zhao, Timothy Regnault

Paediatrics Publications

BACKGROUND: Intrauterine growth restriction and low birth weight (LBW) have been widely reported as an independent risk factor for adult hypercholesterolaemia and increased hepatic cholesterol in a sex-specific manner. However, the specific impact of uteroplacental insufficiency (UPI), a leading cause of LBW in developed world, on hepatic cholesterol metabolism in later life, is ill defined and is clinically relevant in understanding later life liver metabolic health trajectories.

METHODS: Hepatic cholesterol, transcriptome, cholesterol homoeostasis regulatory proteins, and antioxidant markers were studied in UPI-induced LBW and normal birth weight (NBW) male and female guinea pigs at 150 days.

RESULTS: Hepatic free and …

In Vivo Magnetic Resonance Spectroscopy Of Hyperpolarized [1-, Lauren M Smith, Conrad B Pitts, Lanette J Friesen-Waldner, Neetin H Prabhu, Katherine E Mathers, Kevin J Sinclair, Trevor P Wade, Timothy Regnault, Charles A Mckenzie

Paediatrics Publications

BACKGROUND: Alterations in glycolysis are central to the increasing incidence of non-alcoholic fatty liver disease (NAFLD), highlighting a need for in vivo, non-invasive technologies to understand the development of hepatic metabolic aberrations.

PURPOSE: To use hyperpolarized magnetic resonance spectroscopy (MRS) and proton density fat fraction (PDFF) magnetic resonance imaging (MRI) techniques to investigate the effects of a chronic, life-long exposure to the Western diet (WD) in an animal model resulting in NAFLD; to investigate the hypothesis that exposure to the WD will result in NAFLD in association with altered pyruvate metabolism.

STUDY TYPE: Prospective.

ANIMAL MODEL: Twenty-eight male guinea pigs …

Atrx Deletion In Neurons Leads To Sexually Dimorphic Dysregulation Of Mir-137 And Spatial Learning And Memory Deficits., Renee J. Tamming, Vanessa Dumeaux, Yan Jiang, Sarfraz Shafiq, Luana Langlois, Jacob Ellegood, Lily R. Qiu, Jason P. Lerch, Nathalie G. Bérubé

Paediatrics Publications

ATRX gene mutations have been identified in syndromic and non-syndromic intellectual disabilities in humans. ATRX is known to maintain genomic stability in neuroprogenitor cells, but its function in differentiated neurons and memory processes remains largely unresolved. Here, we show that the deletion of neuronal Atrx in mice leads to distinct hippocampal structural defects, fewer presynaptic vesicles, and an enlarged postsynaptic area at CA1 apical dendrite-axon junctions. We identify male-specific impairments in long-term contextual memory and in synaptic gene expression, linked to altered miR-137 levels. We show that ATRX directly binds to the miR-137 locus and that the enrichment of the …

Effects Of A Postnatal Atrx Conditional Knockout In Neurons On Autism-Like Behaviours In Male And Female Mice., Nicole Martin-Kenny, Nathalie G Bérubé

Paediatrics Publications

BACKGROUND: Alpha-thalassemia/mental retardation, X-linked, or ATRX, is an autism susceptibility gene that encodes a chromatin remodeler. Mutations of ATRX result in the ATR-X intellectual disability syndrome and have been identified in autism spectrum disorder (ASD) patients. The mechanisms by which ATRX mutations lead to autism and autistic-like behaviours are not yet known. To address this question, we generated mice with postnatal Atrx inactivation in excitatory neurons of the forebrain and performed a battery of behavioural assays that assess autistic-like behaviours.

METHODS: Male and female mice with a postnatal conditional ablation of ATRX were generated using the Cre/lox system under the …

Evidence Of Increased Hypoxia Signaling In Fetal Liver From Maternal Nutrient Restriction In Mice., Bethany N Radford, Victor K M Han

Paediatrics Publications

BACKGROUND: Intrauterine growth restriction (IUGR) is a pregnancy condition where fetal growth is reduced, and offspring from IUGR pregnancies are at increased risk for type II diabetes as adults. The liver is susceptible to fetal undernutrition experienced by IUGR infants and animal models of growth restriction. This study aimed to examine hepatic expression changes in a maternal nutrient restriction (MNR) mouse model of IUGR to understand fetal adaptations that influence adult metabolism.

METHODS: Liver samples of male offspring from MNR (70% of ad libitum starting at E6.5) or control pregnancies were obtained at E18.5 and differential expression was assessed by …

Insights Image For "Evidence Of Increased Hypoxia Signalling In Fetal Liver From Maternal Nutrient Restriction In Mice"., Bethany N Radford, Victor K M Han

Paediatrics Publications

No abstract provided.

Ctcf Governs The Identity And Migration Of Mge-Derived Cortical Interneurons., Adrienne Elbert, Daniel Vogt, Ashley Watson, Michael Levy, Yan Jiang, Emilie Brûlé, Megan E Rowland, John Rubenstein, Nathalie G Bérubé

Paediatrics Publications

The CCCTC-binding factor (CTCF) is a central regulator of chromatin topology recently linked to neurodevelopmental disorders such as intellectual disability, autism, and schizophrenia. The aim of this study was to identify novel roles of CTCF in the developing mouse brain. We provide evidence that CTCF is required for the expression of the LIM homeodomain factor LHX6 involved in fate determination of cortical interneurons (CINs) that originate in the medial ganglionic eminence (MGE). Conditional

The Loss Of Atrx Increases Susceptibility To Pancreatic Injury And Oncogenic Kras In Female But Not Male Mice., Claire C Young, Ryan M Baker, Christopher J Howlett, Todd Hryciw, Joshua E Herman, Douglas Higgs, Richard Gibbons, Howard Crawford, Arthur Brown, Christopher L Pin

Paediatrics Publications

Background

Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer death in North America, accounting for >30,000 deaths annually. Although somatic activating mutations in KRAS appear in 97% of PDAC patients, additional factors are required to initiate PDAC. Because mutations in genes encoding chromatin remodelling proteins have been implicated in KRAS-mediated PDAC, we investigated whether loss of chromatin remodeler ɑ-thalassemia, mental-retardation, X-linked (ATRX) affects oncogenic KRAS’s ability to promote PDAC. ATRX affects DNA replication, repair, and gene expression and is implicated in other cancers including glioblastomas and pancreatic neuroendocrine tumors. The hypothesis was that deletion of Atrx …

App21 Transgenic Rats Develop Age-Dependent Cognitive Impairment And Microglia Accumulation Within White Matter Tracts., Nina Weishaupt, Qingfan Liu, Sheojung Shin, Ramandeep Singh, Yuksel Agca, Cansu Agca, Vladimir Hachinski, Shawn Narain Whitehead

Paediatrics Publications

Background

Most of the animal models commonly used for preclinical research into Alzheimer's disease (AD) largely fail to address the pathophysiology, including the impact of known risk factors, of the widely diagnosed sporadic form of the disease. Here, we use a transgenic rat (APP21) that does not develop AD-like pathology spontaneously with age, but does develop pathology following vascular stress. To further the potential of this novel rat model as a much-needed pre-clinical animal model of sporadic AD, we characterize APP21 transgenic rats behaviorally and histologically up to 19 months of age.

Methods

The open field test was used as …

Identification Of A Novel Synaptic Protein, Tmtc3, Involved In Periventricular Nodular Heterotopia With Intellectual Disability And Epilepsy, Sali M K Farhan, Kevin C J Nixon, Michelle Everest, Tara N Edwards, Shirley Long, Dmitri Segal, Maria J Knip, Heleen H Arts, Rana Chakrabarti, Jian Wang, John F Robinson, Donald Lee, Seyed M Mirsattari, C Anthony Rupar, Victoria M Siu, Forge Canada Consortium, Michael O Poulter, Robert A Hegele, Jamie M Kramer

Paediatrics Publications

Defects in neuronal migration cause brain malformations, which are associated with intellectual disability (ID) and epilepsy. Using exome sequencing, we identified compound heterozygous variants (p.Arg71His and p. Leu729ThrfsTer6) in TMTC3, encoding transmembrane and tetratricopeptide repeat containing 3, in four siblings with nocturnal seizures and ID. Three of the four siblings have periventricular nodular heterotopia (PVNH), a common brain malformation caused by failure of neurons to migrate from the ventricular zone to the cortex. Expression analysis using patient-derived cells confirmed reduced TMTC3 transcript levels and loss of the TMTC3 protein compared to parental and control cells. As TMTC3 function is currently …

Mutations In Keops-Complex Genes Cause Nephrotic Syndrome With Primary Microcephaly, Daniela A Braun, Jia Rao, Geraldine Mollet, David Schapiro, Marie-Claire Daugeron, Weizhen Tan, Olivier Gribouval, Olivia Boyer, Patrick Revy, Tilman Jobst-Schwan, Johanna Magdalena Schmidt, Jennifer A Lawson, Denny Schanze, Shazia Ashraf, Jeremy F P Ullmann, Charlotte A Hoogstraten, Nathalie Boddaert, Bruno Collinet, Gaëlle Martin, Dominique Liger, Svjetlana Lovric, Monica Furlano, I Chiara Guerrera, Oraly Sanchez-Ferras, Jennifer F Hu, Anne-Claire Boschat, Sylvia Sanquer, Björn Menten, Sarah Vergult, Nina De Rocker, Merlin Airik, Tobias Hermle, Shirlee Shril, Eugen Widmeier, Heon Yung Gee, Won-Il Choi, Carolin E Sadowski, Werner L Pabst, Jillian K Warejko, Ankana Daga, Tamara Basta, Verena Matejas, Karin Scharmann, Sandra D Kienast, Babak Behnam, Brendan Beeson, Amber Begtrup, Malcolm Bruce, Gaik-Siew Ch'ng, Shuan-Pei Lin, Jui-Hsing Chang, Chao-Huei Chen, Megan T Cho, Patrick M Gaffney, Patrick E Gipson, Chyong-Hsin Hsu, Jameela A Kari, Yu-Yuan Ke, Cathy Kiraly-Borri, Wai-Ming Lai, Emmanuelle Lemyre, Rebecca Okashah Littlejohn, Amira Masri, Mastaneh Moghtaderi, Kazuyuki Nakamura, Fatih Ozaltin, Marleen Praet, Chitra Prasad, Agnieszka Prytula, Elizabeth R Roeder, Patrick Rump, Rhonda E Schnur, Takashi Shiihara, Manish D Sinha, Neveen A Soliman, Kenza Soulami, David A Sweetser, Wen-Hui Tsai, Jeng-Daw Tsai, Rezan Topaloglu, Udo Vester, David H Viskochil, Nithiwat Vatanavicharn, Jessica L Waxler, Klaas J Wierenga, Matthias T F Wolf, Sik-Nin Wong, Sebastian A Leidel, Gessica Truglio, Peter C Dedon, Annapurna Poduri, Shrikant Mane, Richard P Lifton, Maxime Bouchard, Peter Kannu, David Chitayat, Daniella Magen, Bert Callewaert, Herman Van Tilbeurgh, Martin Zenker, Corinne Antignac, Friedhelm Hildebrandt

Paediatrics Publications

Galloway-Mowat syndrome (GAMOS) is an autosomal-recessive disease characterized by the combination of early-onset nephrotic syndrome (SRNS) and microcephaly with brain anomalies. Here we identified recessive mutations in OSGEP, TP53RK, TPRKB, and LAGE3, genes encoding the four subunits of the KEOPS complex, in 37 individuals from 32 families with GAMOS. CRISPR-Cas9 knockout in zebrafish and mice recapitulated the human phenotype of primary microcephaly and resulted in early lethality. Knockdown of OSGEP, TP53RK, or TPRKB inhibited cell proliferation, which human mutations did not rescue. Furthermore, knockdown of these genes impaired protein translation, caused endoplasmic reticulum stress, activated DNA-damage-response signaling, and ultimately induced …

Activating Transcription Factor 3 Promotes Loss Of The Acinar Cell Phenotype In Response To Cerulein-Induced Pancreatitis In Mice, Elena N Fazio, Claire C Young, Jelena Toma, Michael Levy, Kurt R Berger, Charis L Johnson, Rashid Mehmood, Patrick Swan, Alphonse Chu, Sean P Cregan, F Jeffrey Dilworth, Christopher J Howlett, Christopher L Pin

Paediatrics Publications

Pancreatitis is a debilitating disease of the exocrine pancreas that, under chronic conditions, is a major susceptibility factor for pancreatic ductal adenocarcinoma (PDAC). Although down-regulation of genes that promote the mature acinar cell fate is required to reduce injury associated with pancreatitis, the factors that promote this repression are unknown. Activating transcription factor 3 (ATF3) is a key mediator of the unfolded protein response, a pathway rapidly activated during pancreatic insult. Using chromatin immunoprecipitation followed by next-generation sequencing, we show that ATF3 is bound to the transcriptional regulatory regions of >30% of differentially expressed genes during the initiation of pancreatitis. …

Mosaic Expression Of Atrx In The Mouse Central Nervous System Causes Memory Deficits, Renee J Tamming, Jennifer R Siu, Yan Jiang, Marco A M Prado, Frank Beier, Nathalie G Bérubé

Paediatrics Publications

The rapid modulation of chromatin organization is thought to play a crucial role in cognitive processes such as memory consolidation. This is supported in part by the dysregulation of many chromatin-remodelling proteins in neurodevelopmental and psychiatric disorders. A key example is ATRX, an X-linked gene commonly mutated in individuals with syndromic and nonsyndromic intellectual disability. The consequences of Atrx inactivation for learning and memory have been difficult to evaluate because of the early lethality of hemizygous-null animals. In this study, we evaluated the outcome of brain-specific Atrx deletion in heterozygous female mice. These mice exhibit a mosaic pattern of ATRX …

Low Birth Weight Followed By Postnatal Over-Nutrition In The Guinea Pig Exposes A Predominant Player In The Development Of Vascular Dysfunction., Jennifer A Thompson, Ousseynou Sarr, Karolina Piorkowska, Robert Gros, Timothy Regnault

Paediatrics Publications

The association between intrauterine growth restriction (IUGR) and hypertension is well established, yet the interaction between IUGR and other pathogenic contributors remains ill-defined. This study examined the independent and interactive effects of fetal growth reduction resulting in low birth weight (LBW), and postnatal Western diet (WD) on vascular function. Growth reduction was induced in pregnant guinea pigs by uterine artery ablation. LBW and normal birth weight (NBW) offspring were randomly assigned to a control diet (CD) or a WD. In young adulthood, length-tension curves were generated in aortic rings and responses to methacholine (MCh) were evaluated in the carotid and …

Analysis Of Neonatal Brain Lacking Atrx Or Mecp2 Reveals Changes In Nucleosome Density, Ctcf Binding And Chromatin Looping, Kristin D Kernohan, Douglas Vernimmen, Gregory B Gloor, Nathalie G. Bérubé

Paediatrics Publications

ATRX and MeCP2 belong to an expanding group of chromatin-associated proteins implicated in human neurodevelopmental disorders, although their gene-regulatory activities are not fully resolved. Loss of ATRX prevents full repression of an imprinted gene network in the postnatal brain and in this study we address the mechanistic aspects of this regulation. We show that ATRX binds many imprinted domains individually but that transient co-localization between imprinted domains in the nuclei of neurons does not require ATRX. We demonstrate that MeCP2 is required for ATRX recruitment and that deficiency of either ATRX or MeCP2 causes decreased frequency of long-range chromatin interactions …

Low Birth Weight Male Guinea Pig Offspring Display Increased Visceral Adiposity In Early Adulthood., Ousseynou Sarr, Jennifer A Thompson, Lin Zhao, Ting-Yim Lee, Timothy Regnault

Paediatrics Publications

Uteroplacental insufficiency (UPI)-induced intrauterine growth restriction (IUGR) predisposes individuals to adult visceral obesity. We postulated that low birth weight (LBW) offspring, from UPI-induced IUGR pregnancies, would display a visceral adipose lipogenic molecular signature involving altered gene expression, phosphorylation status of proteins of the lipid synthesis pathway and microRNA (miR) expression profile, occurring in association with increased visceral adiposity. Normal birth weight (NBW) and LBW (obtained by uterine artery ablation) male guinea pig pups were fed a control diet from weaning to 145 days and sacrificed. Despite being lighter at birth, LBW pups displayed body weights similar to NBW offspring at …

The Effect Of Intermittent Umbilical Cord Occlusion On Elastin Composition In The Ovine Fetus., Jennifer A Thompson, Sarah A Gimbel, Bryan S Richardson, Robert Gagnon, Timothy Regnault

Paediatrics Publications

This study aimed to determine the effect of varying degrees of intermittent umbilical cord occlusion (UCO) on arterial elastin composition. Over 4 days, chronically catheterized late gestation fetal sheep received 5 total UCO per day lasting 1 min/h (mild group: n = 6), 2 min/h (moderate group: n = 4), 3 min/h (severe group; n = 6); or no occlusion (control group: n = 7). Each group was evaluated for elastin content of the carotid and superior mesenteric artery (SMA), the arterial pressure response to UCO, and plasma cortisol concentration. Elastin content of the carotid artery was significantly increased by …

Intrauterine Growth Restriction Increases Fetal Hepatic Gluconeogenic Capacity And Reduces Messenger Ribonucleic Acid Translation Initiation And Nutrient Sensing In Fetal Liver And Skeletal Muscle., Stephanie R Thorn, Timothy Regnault, Laura D Brown, Paul J Rozance, Jane Keng, Michael Roper, Randall B Wilkening, William W Hay, Jacob E Friedman

Paediatrics Publications

Expression of key metabolic genes and proteins involved in mRNA translation, energy sensing, and glucose metabolism in liver and skeletal muscle were investigated in a late-gestation fetal sheep model of placental insufficiency intrauterine growth restriction (PI-IUGR). PI-IUGR fetuses weighed 55% less; had reduced oxygen, glucose, isoleucine, insulin, and IGF-I levels; and had 40% reduction in net branched chain amino acid uptake. In PI-IUGR skeletal muscle, levels of insulin receptor were increased 80%, whereas phosphoinositide-3 kinase (p85) and protein kinase B (AKT2) were reduced by 40%. Expression of eukaryotic initiation factor-4e was reduced 45% in liver, suggesting a unique mechanism limiting …

Effects Of Early Gestation Gh Administration On Placental And Fetal Development In Sheep., Casey D Wright, Ryan J Orbus, Timothy Regnault, Russell V Anthony

Paediatrics Publications

Ovine GH (oGH) is synthesized in placental tissue during maximal placental growth and development. Our objectives were to localize oGH mRNA in the placenta, and study the impact of exogenous GH on twin pregnancies during the normal window (35-55 days of gestational age; dGA) of placental expression. In situ hybridization localized oGH mRNA in uterine luminal epithelium but not in tissues of fetal origin. While maternal GH and IGF-I concentrations were increased (P

Chronic Late-Gestation Hypoglycemia Upregulates Hepatic Pepck Associated With Increased Pgc1alpha Mrna And Phosphorylated Creb In Fetal Sheep., Paul J Rozance, Sean W Limesand, James S Barry, Laura D Brown, Stephanie R Thorn, Dan Loturco, Timothy Regnault, Jacob E Friedman, William W Hay

Paediatrics Publications

Hepatic glucose production is normally activated at birth but has been observed in response to experimental hypoglycemia in fetal sheep. The cellular basis for this process remains unknown. We determined the impact of 2 wk of fetal hypoglycemia during late gestation on enzymes responsible for hepatic gluconeogenesis, focusing on the insulin-signaling pathway, transcription factors, and coactivators that regulate gluconeogenesis. Hepatic phosphoenolpyruvate carboxykinase and glucose-6-phosphatase mRNA increased 12-fold and 7-fold, respectively, following chronic hypoglycemia with no change in hepatic glycogen. Chronic hypoglycemia decreased fetal plasma insulin with no change in glucagon but increased plasma cortisol 3.5-fold. Peroxisome proliferator-activated receptor-gamma coactivator-1alpha mRNA …

The Expression Of Ovine Placental Lactogen, Star And Progesterone-Associated Steroidogenic Enzymes In Placentae Of Overnourished Growing Adolescent Ewes., Richard G Lea, Peter Wooding, Ian Stewart, Lisa T Hannah, Stephen Morton, Karen Wallace, Raymond P Aitken, John S Milne, Timothy Regnault, Russell V Anthony, Jacqueline M Wallace

Paediatrics Publications

Overnourishing pregnant adolescent sheep promotes maternal growth but reduces placental mass, lamb birth weight and circulating progesterone. This study aimed to determine whether altered progesterone reflected transcript abundance for StAR (cholesterol transporter) and the steroidogenic enzymes (Cyp11A1, Hsd3b and Cyp17). Circulating and placental expression of ovine placental lactogen (oPL) was also investigated. Adolescent ewes with singleton pregnancies were fed high (H) or moderate (M) nutrient intake diets to restrict or support placental growth. Experiment 1: peripheral progesterone and oPL concentrations were measured in H (n=7) and M (n=6) animals across gestation (days 7-140). Experiment 2: progesterone was measured to mid- …

Altered Placental And Fetal Expression Of Igfs And Igf-Binding Proteins Associated With Intrauterine Growth Restriction In Fetal Sheep During Early And Mid-Pregnancy., Barbra De Vrijer, Meredith L Davidsen, Randall B Wilkening, Russell V Anthony, Timothy Regnault

Paediatrics Publications

The insulin-like growth factors (IGFs) are postulated to be altered in association with the development of intrauterine growth restriction (IUGR). The present studies examined placental and fetal hepatic mRNA concentration of components of the IGF system at two time points (55 and 90 d gestational age, dGA; Term 147 dGA) in a hyperthermia (HT)-induced sheep model of placental insufficiency-IUGR. Maternal plasma insulin and IGF-I were constant at 55 and 90 dGA and were unaffected by treatment. Umbilical vein insulin concentrations tended to be reduced at 90 dGA following HT exposure. Caruncle IGF-I mRNA was increased at 90 dGA in HT …

Placental Expression Of Angiopoietin-1, Angiopoietin-2 And Tie-2 During Placental Development In An Ovine Model Of Placental Insufficiency-Fetal Growth Restriction., Amy S Erickson Hagen, Ryan J Orbus, Randall B Wilkening, Timothy Regnault, Russell V Anthony

Paediatrics Publications

Fetal growth restriction (FGR) is associated with increased perinatal morbidity and mortality, and often results from functional placental insufficiency. Placentation requires extensive vasculogenesis and subsequent angiogenesis, in both maternal and fetal tissues. Angiopoietin-1 (Ang-1) and Angiopoietin-2 (Ang-2) are angiogenic growth factors expressed in the placenta, and compete for binding to a common receptor, Tunica interna endothelial cell kinase-2 (Tie-2). Our objective was to examine Ang-1, Ang-2 and Tie-2 expression in ovine placental tissue obtained from normal and FGR pregnancies throughout gestation. Fetal cotyledon and maternal caruncle tissue concentrations of Ang-1, Ang-2 and Tie-2 mRNA were assessed by real-time reverse transcriptase-polymerase …

Investigating The Causes Of Low Birth Weight In Contrasting Ovine Paradigms., J M Wallace, Timothy Regnault, S W Limesand, W W Hay, R V Anthony

Paediatrics Publications

Intrauterine growth restriction (IUGR) still accounts for a large incidence of infant mortality and morbidity worldwide. Many of the circulatory and transport properties of the sheep placenta are similar to those of the human placenta and as such, the pregnant sheep offers an excellent model in which to study the development of IUGR. Two natural models of ovine IUGR are those of hyperthermic exposure during pregnancy, and adolescent overfeeding, also during pregnancy. Both models yield significantly reduced placental weights and an asymmetrically growth-restricted fetus, and display altered maternal hormone concentrations, indicative of an impaired trophoblast capacity. Additionally, impaired placental angiogenesis …