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Huang Y, Flentke GR, Smith SM. Alcohol induces p53-mediated apoptosis in neural crest by stimulating an AMPK-mediated suppression of TORC1, p70/S6K, and ribosomal biogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.02.601754. [PMID: 39005448 PMCID: PMC11244973 DOI: 10.1101/2024.07.02.601754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
Prenatal alcohol exposure is a leading cause of permanent neurodevelopmental disability and can feature distinctive craniofacial deficits that partly originate from the apoptotic deletion of craniofacial progenitors, a stem cell lineage called the neural crest (NC). We recently demonstrated that alcohol causes nucleolar stress in NC through its suppression of ribosome biogenesis (RBG) and this suppression is causative in their p53/MDM2-mediated apoptosis. Here, we show that this nucleolar stress originates from alcohol's activation of AMPK, which suppresses TORC1 and the p70/S6K-mediated stimulation of RBG. Alcohol-exposed cells of the pluripotent, primary cranial NC line O9-1 were evaluated with respect to their p70/S6K, TORC1, and AMPK activity. The functional impact of these signals with respect to RBG, p53, and apoptosis were assessed using gain-of-function constructs and small molecule mediators. Alcohol rapidly (<2hr) increased pAMPK, pTSC2, pRaptor, p-mTOR(S2446), and reduced both total and p-p70/S6K in NC cells. These changes persisted for at least 12hr to 18hr following alcohol exposure. Attenuation of these signals via gain- or loss-of-function approaches that targeted AMPK, p70/S6K, or TORC1 prevented alcohol's suppression of rRNA synthesis and the induction of p53-stimulated apoptosis. We conclude that alcohol induces ribosome dysbiogenesis and activates their p53/MDM2-mediated apoptosis via its activation of pAMPK, which in turn activates TSC2 and Raptor to suppress the TORC1-p70/S6K-mediated promotion of ribosome biogenesis. This represents a novel mechanism underlying alcohol's neurotoxicity and is consistent with findings that TORC1-p70/S6K networks are critical for cranial NC survival.
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Flentke GR, Wilkie TE, Baulch J, Huang Y, Smith SM. Alcohol exposure suppresses ribosome biogenesis and causes nucleolar stress in cranial neural crest cells. PLoS One 2024; 19:e0304557. [PMID: 38941348 PMCID: PMC11213321 DOI: 10.1371/journal.pone.0304557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 05/14/2024] [Indexed: 06/30/2024] Open
Abstract
Prenatal alcohol exposure (PAE) causes cognitive impairment and a distinctive craniofacial dysmorphology, due in part to apoptotic losses of the pluripotent cranial neural crest cells (CNCs) that form facial bones and cartilage. We previously reported that PAE rapidly represses expression of >70 ribosomal proteins (padj = 10-E47). Ribosome dysbiogenesis causes nucleolar stress and activates p53-MDM2-mediated apoptosis. Using primary avian CNCs and the murine CNC line O9-1, we tested whether nucleolar stress and p53-MDM2 signaling mediates this apoptosis. We further tested whether haploinsufficiency in genes that govern ribosome biogenesis, using a blocking morpholino approach, synergizes with alcohol to worsen craniofacial outcomes in a zebrafish model. In both avian and murine CNCs, pharmacologically relevant alcohol exposure (20mM, 2hr) causes the dissolution of nucleolar structures and the loss of rRNA synthesis; this nucleolar stress persisted for 18-24hr. This was followed by reduced proliferation, stabilization of nuclear p53, and apoptosis that was prevented by overexpression of MDM2 or dominant-negative p53. In zebrafish embryos, low-dose alcohol or morpholinos directed against ribosomal proteins Rpl5a, Rpl11, and Rps3a, the Tcof homolog Nolc1, or mdm2 separately caused modest craniofacial malformations, whereas these blocking morpholinos synergized with low-dose alcohol to reduce and even eliminate facial elements. Similar results were obtained using a small molecule inhibitor of RNA Polymerase 1, CX5461, whereas p53-blocking morpholinos normalized craniofacial outcomes under high-dose alcohol. Transcriptome analysis affirmed that alcohol suppressed the expression of >150 genes essential for ribosome biogenesis. We conclude that alcohol causes the apoptosis of CNCs, at least in part, by suppressing ribosome biogenesis and invoking a nucleolar stress that initiates their p53-MDM2 mediated apoptosis. We further note that the facial deficits that typify PAE and some ribosomopathies share features including reduced philtrum, upper lip, and epicanthal distance, suggesting the facial deficits of PAE represent, in part, a ribosomopathy.
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Affiliation(s)
- George R. Flentke
- UNC Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC, United States of America
| | - Thomas E. Wilkie
- UNC Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC, United States of America
| | - Josh Baulch
- UNC Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC, United States of America
| | - Yanping Huang
- UNC Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC, United States of America
| | - Susan M. Smith
- UNC Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC, United States of America
- Department of Nutrition, University of North Carolina at Chapel Hill, Kannapolis, NC, United States of America
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Huang Y, Flentke GR, Rivera OC, Saini N, Mooney SM, Smith SM. Alcohol Exposure Induces Nucleolar Stress and Apoptosis in Mouse Neural Stem Cells and Late-Term Fetal Brain. Cells 2024; 13:440. [PMID: 38474404 PMCID: PMC10931382 DOI: 10.3390/cells13050440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 02/21/2024] [Accepted: 02/27/2024] [Indexed: 03/14/2024] Open
Abstract
Prenatal alcohol exposure (PAE) is a leading cause of neurodevelopmental disability through its induction of neuronal growth dysfunction through incompletely understood mechanisms. Ribosome biogenesis regulates cell cycle progression through p53 and the nucleolar cell stress response. Whether those processes are targeted by alcohol is unknown. Pregnant C57BL/6J mice received 3 g alcohol/kg daily at E8.5-E17.5. Transcriptome sequencing was performed on the E17.5 fetal cortex. Additionally, primary neural stem cells (NSCs) were isolated from the E14.5 cerebral cortex and exposed to alcohol to evaluate nucleolar stress and p53/MDM2 signaling. Alcohol suppressed KEGG pathways involving ribosome biogenesis (rRNA synthesis/processing and ribosomal proteins) and genes that are mechanistic in ribosomopathies (Polr1d, Rpl11; Rpl35; Nhp2); this was accompanied by nucleolar dissolution and p53 stabilization. In primary NSCs, alcohol reduced rRNA synthesis, caused nucleolar loss, suppressed proliferation, stabilized nuclear p53, and caused apoptosis that was prevented by dominant-negative p53 and MDM2 overexpression. Alcohol's actions were dose-dependent and rapid, and rRNA synthesis was suppressed between 30 and 60 min following alcohol exposure. The alcohol-mediated deficits in ribosomal protein expression were correlated with fetal brain weight reductions. This is the first report describing that pharmacologically relevant alcohol levels suppress ribosome biogenesis, induce nucleolar stress in neuronal populations, and involve the ribosomal/MDM2/p53 pathway to cause growth arrest and apoptosis. This represents a novel mechanism of alcohol-mediated neuronal damage.
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Affiliation(s)
- Yanping Huang
- UNC Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA (N.S.); (S.M.M.)
| | - George R. Flentke
- UNC Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA (N.S.); (S.M.M.)
| | - Olivia C. Rivera
- UNC Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA (N.S.); (S.M.M.)
| | - Nipun Saini
- UNC Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA (N.S.); (S.M.M.)
| | - Sandra M. Mooney
- UNC Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA (N.S.); (S.M.M.)
- Department of Nutrition, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA
| | - Susan M. Smith
- UNC Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA (N.S.); (S.M.M.)
- Department of Nutrition, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA
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Darbinian N, Gallia GL, Darbinyan A, Vadachkoria E, Merabova N, Moore A, Goetzl L, Amini S, Selzer ME. Effects of In Utero EtOH Exposure on 18S Ribosomal RNA Processing: Contribution to Fetal Alcohol Spectrum Disorder. Int J Mol Sci 2023; 24:13714. [PMID: 37762017 PMCID: PMC10531167 DOI: 10.3390/ijms241813714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 08/28/2023] [Accepted: 08/29/2023] [Indexed: 09/29/2023] Open
Abstract
Fetal alcohol spectrum disorders (FASD) are leading causes of neurodevelopmental disability. The mechanisms by which alcohol (EtOH) disrupts fetal brain development are incompletely understood, as are the genetic factors that modify individual vulnerability. Because the phenotype abnormalities of FASD are so varied and widespread, we investigated whether fetal exposure to EtOH disrupts ribosome biogenesis and the processing of pre-ribosomal RNAs and ribosome assembly, by determining the effect of exposure to EtOH on the developmental expression of 18S rRNA and its cleaved forms, members of a novel class of short non-coding RNAs (srRNAs). In vitro neuronal cultures and fetal brains (11-22 weeks) were collected according to an IRB-approved protocol. Twenty EtOH-exposed brains from the first and second trimester were compared with ten unexposed controls matched for gestational age and fetal gender. Twenty fetal-brain-derived exosomes (FB-Es) were isolated from matching maternal blood. RNA was isolated using Qiagen RNA isolation kits. Fetal brain srRNA expression was quantified by ddPCR. srRNAs were expressed in the human brain and FB-Es during fetal development. EtOH exposure slightly decreased srRNA expression (1.1-fold; p = 0.03). Addition of srRNAs to in vitro neuronal cultures inhibited EtOH-induced caspase-3 activation (1.6-fold, p = 0.002) and increased cell survival (4.7%, p = 0.034). The addition of exogenous srRNAs reversed the EtOH-mediated downregulation of srRNAs (2-fold, p = 0.002). EtOH exposure suppressed expression of srRNAs in the developing brain, increased activity of caspase-3, and inhibited neuronal survival. Exogenous srRNAs reversed this effect, possibly by stabilizing endogenous srRNAs, or by increasing the association of cellular proteins with srRNAs, modifying gene transcription. Finally, the reduction in 18S rRNA levels correlated closely with the reduction in fetal eye diameter, an anatomical hallmark of FASD. The findings suggest a potential mechanism for EtOH-mediated neurotoxicity via alterations in 18S rRNA processing and the use of FB-Es for early diagnosis of FASD. Ribosome biogenesis may be a novel target to ameliorate FASD in utero or after birth. These findings are consistent with observations that gene-environment interactions contribute to FASD vulnerability.
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Affiliation(s)
- Nune Darbinian
- Center for Neural Repair and Rehabilitation Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; (E.V.); (N.M.); (A.M.)
| | - Gary L. Gallia
- Department of Neurosurgery, Johns Hopkins Hospital, Baltimore, MD 21287, USA;
| | - Armine Darbinyan
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06520, USA;
| | - Ekaterina Vadachkoria
- Center for Neural Repair and Rehabilitation Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; (E.V.); (N.M.); (A.M.)
| | - Nana Merabova
- Center for Neural Repair and Rehabilitation Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; (E.V.); (N.M.); (A.M.)
- Medical College of Wisconsin-Prevea Health, Green Bay, WI 54304, USA
| | - Amos Moore
- Center for Neural Repair and Rehabilitation Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; (E.V.); (N.M.); (A.M.)
| | - Laura Goetzl
- Department of Obstetrics & Gynecology, University of Texas, Houston, TX 77030, USA;
| | - Shohreh Amini
- Department of Biology, College of Science and Technology, Temple University, Philadelphia, PA 19122, USA;
| | - Michael E. Selzer
- Center for Neural Repair and Rehabilitation Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; (E.V.); (N.M.); (A.M.)
- Departments of Neurology and Neural Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
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Chen SY, Kannan M. Neural crest cells and fetal alcohol spectrum disorders: Mechanisms and potential targets for prevention. Pharmacol Res 2023; 194:106855. [PMID: 37460002 PMCID: PMC10528842 DOI: 10.1016/j.phrs.2023.106855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/23/2023] [Accepted: 07/14/2023] [Indexed: 07/26/2023]
Abstract
Fetal alcohol spectrum disorders (FASD) are a group of preventable and nongenetic birth defects caused by prenatal alcohol exposure that can result in a range of cognitive, behavioral, emotional, and functioning deficits, as well as craniofacial dysmorphology and other congenital defects. During embryonic development, neural crest cells (NCCs) play a critical role in giving rise to many cell types in the developing embryos, including those in the peripheral nervous system and craniofacial structures. Ethanol exposure during this critical period can have detrimental effects on NCC induction, migration, differentiation, and survival, leading to a broad range of structural and functional abnormalities observed in individuals with FASD. This review article provides an overview of the current knowledge on the detrimental effects of ethanol on NCC induction, migration, differentiation, and survival. The article also examines the molecular mechanisms involved in ethanol-induced NCC dysfunction, such as oxidative stress, altered gene expression, apoptosis, epigenetic modifications, and other signaling pathways. Furthermore, the review highlights potential therapeutic strategies for preventing or mitigating the detrimental effects of ethanol on NCCs and reducing the risk of FASD. Overall, this article offers a comprehensive overview of the current understanding of the impact of ethanol on NCCs and its role in FASD, shedding light on potential avenues for future research and intervention.
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Affiliation(s)
- Shao-Yu Chen
- Department of Pharmacology and Toxicology, University of Louisville Health Sciences Center, Louisville, KY 40292, USA; University of Louisville Alcohol Research Center, Louisville, KY 40292, USA.
| | - Maharajan Kannan
- Department of Pharmacology and Toxicology, University of Louisville Health Sciences Center, Louisville, KY 40292, USA; University of Louisville Alcohol Research Center, Louisville, KY 40292, USA.
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Boschen KE, Steensen MC, Simon JM, Parnell SE. Short-term transcriptomic changes in the mouse neural tube induced by an acute alcohol exposure. Alcohol 2023; 106:1-9. [PMID: 36202274 PMCID: PMC11096843 DOI: 10.1016/j.alcohol.2022.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 08/25/2022] [Accepted: 09/06/2022] [Indexed: 01/28/2023]
Abstract
Alcohol exposure during the formation and closure of the neural tube, or neurulation (embryonic day [E] 8-10 in mice; ∼4th week of human pregnancy), perturbs development of midline brain structures and significantly disrupts gene expression in the rostroventral neural tube (RVNT). Previously, alcohol exposure during neurulation was found to alter gene pathways related to cell proliferation, p53 signaling, ribosome biogenesis, immune signaling, organogenesis, and cell migration 6 or 24 h after administration. Our current study expands upon this work by investigating short-term gene expression changes in the RVNT following a single binge-like alcohol exposure during neurulation. Female C57BL/6J mice were administered a single dose of 2.9 g/kg alcohol or vehicle on E9.0 to target mid-neurulation. The RVNTs of stage-matched embryos were collected 2 or 4 h after exposure and processed for RNA-seq. Functional profiling was performed with g:Profiler, as well as with the CiliaCarta and DisGeNet databases. Two hours following E9.0 alcohol exposure, 650 genes in the RVNT were differentially expressed. Functional enrichment analysis revealed that pathways related to cellular metabolism, gene expression, cell cycle, organogenesis, and Hedgehog signaling were down-regulated, and pathways related to cellular stress response, p53 signaling, and hypoxia were up-regulated by alcohol. Four hours after alcohol exposure, 225 genes were differentially expressed. Biological processes related to metabolism, RNA binding, ribosome biogenesis, and methylation were down-regulated, while protein localization and binding, autophagy, and intracellular signaling pathways were up-regulated. Two hours after alcohol exposure, the differentially expressed genes were associated with disease terms related to eye and craniofacial development and anoxia. These data provide further information regarding the biological functions targeted by alcohol exposure during neurulation in regions of the neural tube that give rise to alcohol-sensitive midline brain structures. Disruption of these gene pathways contributes to the craniofacial and brain malformations associated with prenatal alcohol exposure.
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Affiliation(s)
- Karen E Boschen
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Melina C Steensen
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Jeremy M Simon
- Carolina Institute for Developmental Disabilities, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States; UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States; Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Scott E Parnell
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States; Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.
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Helfrich KK, Saini N, Kwan STC, Rivera OC, Mooney SM, Smith SM. Fetal anemia and elevated hepcidin in a mouse model of fetal alcohol spectrum disorder. Pediatr Res 2023:10.1038/s41390-023-02469-6. [PMID: 36702950 DOI: 10.1038/s41390-023-02469-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 12/19/2022] [Accepted: 01/01/2023] [Indexed: 01/27/2023]
Abstract
INTRODUCTION Prenatal alcohol exposure (PAE) impairs offspring growth and cognition, and this is worsened by concurrent iron deficiency. Alcohol disrupts fetal iron metabolism and produces functional iron deficiency, even when maternal iron status is adequate. We used a mouse model of moderate PAE to investigate the mechanisms underlying this dysregulated iron status. METHODS C57BL/6J female mice received 3 g/kg alcohol daily from embryonic day (E) 8.5-17.5 and were assessed at E17.5. RESULTS Alcohol reduced fetal hemoglobin, hematocrit, and red blood cell counts, despite elevated erythropoietin production. Alcohol suppressed maternal hepcidin expression and the upstream iron-sensing BMP/SMAD pathway, consistent with its effects in the nonpregnant state. In contrast, alcohol elevated fetal hepcidin, although this was not accompanied by an upregulation of the BMP/SMAD or proinflammatory IL-6/STAT3 pathways. Fetal expression of hepatic genes contributing to hemoglobin synthesis and iron metabolism were unaffected by alcohol, whereas those affecting ribosome biogenesis were suppressed, suggesting a novel candidate effector for this fetal anemia. CONCLUSION These data confirm and extend prior observations that PAE disrupts maternal and fetal iron metabolism and impairs the fetus's ability to regulate iron status. We propose this dysregulation increases gestational iron needs and represents a conserved response to PAE. IMPACT Prenatal alcohol exposure causes a functional iron deficiency in a model that also impairs cognition in later life. Prenatal alcohol exposure causes fetal anemia. This fetal anemia is accompanied by elevated hepcidin and erythropoietin. Findings are consistent with prior observations that prenatal alcohol exposure increases maternal-fetal iron requirements during pregnancy.
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Affiliation(s)
- Kaylee K Helfrich
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC, 28081, USA.,Department of Nutrition, University of North Carolina at Chapel Hill, Kannapolis, NC, 28081, USA
| | - Nipun Saini
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC, 28081, USA
| | - Sze Ting Cecilia Kwan
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC, 28081, USA
| | - Olivia C Rivera
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC, 28081, USA
| | - Sandra M Mooney
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC, 28081, USA.,Department of Nutrition, University of North Carolina at Chapel Hill, Kannapolis, NC, 28081, USA
| | - Susan M Smith
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC, 28081, USA. .,Department of Nutrition, University of North Carolina at Chapel Hill, Kannapolis, NC, 28081, USA.
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Everson JL, Eberhart JK. Gene-alcohol interactions in birth defects. Curr Top Dev Biol 2022; 152:77-113. [PMID: 36707215 PMCID: PMC9897481 DOI: 10.1016/bs.ctdb.2022.10.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Most human birth defects are thought to result from complex interactions between combinations of genetic and environmental factors. This is true even for conditions that, at face value, may appear simple and straightforward, like fetal alcohol spectrum disorders (FASD). FASD describe the full range of structural and neurological disruptions that result from prenatal alcohol exposure. While FASD require alcohol exposure, evidence from human and animal model studies demonstrate that additional genetic and/or environmental factors can influence the embryo's susceptibility to alcohol. Only a limited number of alcohol interactions in birth defects have been identified, with many sensitizing genetic and environmental factors likely yet to be identified. Because of this, while unsatisfying, there is no definitively "safe" dose of alcohol for all pregnancies. Determining these other factors, as well as mechanistically characterizing known interactions, is critical for better understanding and preventing FASD and requires combined scrutiny of human and model organism studies.
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Affiliation(s)
- Joshua L Everson
- Department of Molecular Biosciences, School of Natural Sciences, University of Texas at Austin, Austin, TX, United States; Waggoner Center for Alcohol and Addiction Research, School of Pharmacy, University of Texas at Austin, Austin, TX, United States.
| | - Johann K Eberhart
- Department of Molecular Biosciences, School of Natural Sciences, University of Texas at Austin, Austin, TX, United States; Waggoner Center for Alcohol and Addiction Research, School of Pharmacy, University of Texas at Austin, Austin, TX, United States.
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Yoon B, Yeung P, Santistevan N, Bluhm LE, Kawasaki K, Kueper J, Dubielzig R, VanOudenhove J, Cotney J, Liao EC, Grinblat Y. Zebrafish models of alx-linked frontonasal dysplasia reveal a role for Alx1 and Alx3 in the anterior segment and vasculature of the developing eye. Biol Open 2022; 11:bio059189. [PMID: 35142342 PMCID: PMC9167625 DOI: 10.1242/bio.059189] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 01/28/2022] [Indexed: 11/18/2022] Open
Abstract
The cellular and genetic mechanisms that coordinate formation of facial sensory structures with surrounding skeletal and soft tissue elements remain poorly understood. Alx1, a homeobox transcription factor, is a key regulator of midfacial morphogenesis. ALX1 mutations in humans are linked to severe congenital anomalies of the facial skeleton (frontonasal dysplasia, FND) with malformation or absence of eyes and orbital contents (micro- and anophthalmia). Zebrafish with loss-of-function alx1 mutations develop with craniofacial and ocular defects of variable penetrance, likely due to compensatory upregulation in expression of a paralogous gene, alx3. Here we show that zebrafish alx1;alx3 mutants develop with highly penetrant cranial and ocular defects that resemble human ALX1-linked FND. alx1 and alx3 are expressed in anterior cranial neural crest (aCNC), which gives rise to the anterior neurocranium (ANC), anterior segment structures of the eye and vascular pericytes. Consistent with a functional requirement for alx genes in aCNC, alx1; alx3 mutants develop with nearly absent ANC and grossly aberrant hyaloid vasculature and ocular anterior segment, but normal retina. In vivo lineage labeling identified a requirement for alx1 and alx3 during aCNC migration, and transcriptomic analysis suggested oxidative stress response as a key target mechanism of this function. Oxidative stress is a hallmark of fetal alcohol toxicity, and we found increased penetrance of facial and ocular malformations in alx1 mutants exposed to ethanol, consistent with a protective role for alx1 against ethanol toxicity. Collectively, these data demonstrate a conserved role for zebrafish alx genes in controlling ocular and facial development, and a novel role in protecting these key midfacial structures from ethanol toxicity during embryogenesis. These data also reveal novel roles for alx genes in ocular anterior segment formation and vascular development and suggest that retinal deficits in alx mutants may be secondary to aberrant ocular vascularization and anterior segment defects. This study establishes robust zebrafish models for interrogating conserved genetic mechanisms that coordinate facial and ocular development, and for exploring gene--environment interactions relevant to fetal alcohol syndrome.
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Affiliation(s)
- Baul Yoon
- Departments of Integrative Biology and Neuroscience, University of Wisconsin, Madison, WI 53706, USA
- Genetics Ph.D. Training Program, University of Wisconsin, Madison, WI 53706, USA
| | - Pan Yeung
- Center for Regenerative Medicine, Department of Surgery, Massachusetts General Hospital, Harvard Medical School, and Shriners Hospital for Children, Boston, 02114, USA
| | - Nicholas Santistevan
- Departments of Integrative Biology and Neuroscience, University of Wisconsin, Madison, WI 53706, USA
- Genetics Ph.D. Training Program, University of Wisconsin, Madison, WI 53706, USA
| | - Lauren E. Bluhm
- Departments of Integrative Biology and Neuroscience, University of Wisconsin, Madison, WI 53706, USA
| | - Kenta Kawasaki
- Center for Regenerative Medicine, Department of Surgery, Massachusetts General Hospital, Harvard Medical School, and Shriners Hospital for Children, Boston, 02114, USA
| | - Janina Kueper
- Center for Regenerative Medicine, Department of Surgery, Massachusetts General Hospital, Harvard Medical School, and Shriners Hospital for Children, Boston, 02114, USA
- Institute of Human Genetics, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Richard Dubielzig
- Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW), University of Wisconsin, Madison, WI 53706, USA
| | - Jennifer VanOudenhove
- University of Connecticut School of Medicine, Department of Genetics and Genome Sciences, Farmington, CT 06030, USA
| | - Justin Cotney
- University of Connecticut School of Medicine, Department of Genetics and Genome Sciences, Farmington, CT 06030, USA
| | - Eric C. Liao
- Center for Regenerative Medicine, Department of Surgery, Massachusetts General Hospital, Harvard Medical School, and Shriners Hospital for Children, Boston, 02114, USA
| | - Yevgenya Grinblat
- Departments of Integrative Biology and Neuroscience, University of Wisconsin, Madison, WI 53706, USA
- Genetics Ph.D. Training Program, University of Wisconsin, Madison, WI 53706, USA
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Curnow E, Wang Y. New Animal Models for Understanding FMRP Functions and FXS Pathology. Cells 2022; 11:1628. [PMID: 35626665 PMCID: PMC9140010 DOI: 10.3390/cells11101628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 05/03/2022] [Accepted: 05/09/2022] [Indexed: 11/16/2022] Open
Abstract
Fragile X encompasses a range of genetic conditions, all of which result as a function of changes within the FMR1 gene and abnormal production and/or expression of the FMR1 gene products. Individuals with Fragile X syndrome (FXS), the most common heritable form of intellectual disability, have a full-mutation sequence (>200 CGG repeats) which brings about transcriptional silencing of FMR1 and loss of FMR protein (FMRP). Despite considerable progress in our understanding of FXS, safe, effective, and reliable treatments that either prevent or reduce the severity of the FXS phenotype have not been approved. While current FXS animal models contribute their own unique understanding to the molecular, cellular, physiological, and behavioral deficits associated with FXS, no single animal model is able to fully recreate the FXS phenotype. This review will describe the status and rationale in the development, validation, and utility of three emerging animal model systems for FXS, namely the nonhuman primate (NHP), Mongolian gerbil, and chicken. These developing animal models will provide a sophisticated resource in which the deficits in complex functions of perception, action, and cognition in the human disorder are accurately reflected and aid in the successful translation of novel therapeutics and interventions to the clinic setting.
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Affiliation(s)
- Eliza Curnow
- REI Division, Department of ObGyn, University of Washington, Seattle, WA 98195, USA
- Washington National Primate Research Center, University of Washington, Seattle, WA 98195, USA
| | - Yuan Wang
- Program in Neuroscience, Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA
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11
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Fernandes Y, Lovely CB. Zebrafish models of fetal alcohol spectrum disorders. Genesis 2021; 59:e23460. [PMID: 34739740 DOI: 10.1002/dvg.23460] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 10/15/2021] [Accepted: 10/18/2021] [Indexed: 12/14/2022]
Abstract
Fetal alcohol spectrum disorder (FASD) describes a wide range of structural deficits and cognitive impairments. FASD impacts up to 5% of children born in the United States each year, making ethanol one of the most common teratogens. Due to limitations and ethical concerns, studies in humans are limited in their ability to study FASD. Animal models have proven critical in identifying and characterizing the mechanisms underlying FASD. In this review, we will focus on the attributes of zebrafish that make it a strong model in which to study ethanol-induced developmental defects. Zebrafish have several attributes that make it an ideal model in which to study FASD. Zebrafish produced large numbers of externally fertilized, translucent embryos. With a high degree of genetic amenability, zebrafish are at the forefront of identifying and characterizing the gene-ethanol interactions that underlie FASD. Work from multiple labs has shown that embryonic ethanol exposures result in defects in craniofacial, cardiac, ocular, and neural development. In addition to structural defects, ethanol-induced cognitive and behavioral impairments have been studied in zebrafish. Building upon these studies, work has identified ethanol-sensitive loci that underlie the developmental defects. However, analyses show there is still much to be learned of these gene-ethanol interactions. The zebrafish is ideally suited to expand our understanding of gene-ethanol interactions and their impact on FASD. Because of the conservation of gene function between zebrafish and humans, these studies will directly translate to studies of candidate genes in human populations and allow for better diagnosis and treatment of FASD.
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Affiliation(s)
- Yohaan Fernandes
- Department of Biology, University of South Dakota, Vermillion, South Dakota, USA
| | - C Ben Lovely
- Department of Biochemistry and Molecular Genetics, Alcohol Research Center, University of Louisville, Louisville, Kentucky, USA
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12
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Pinson MR, Holloway KN, Douglas JC, Kane CJM, Miranda RC, Drew PD. Divergent and overlapping hippocampal and cerebellar transcriptome responses following developmental ethanol exposure during the secondary neurogenic period. Alcohol Clin Exp Res 2021; 45:1408-1423. [PMID: 34060105 PMCID: PMC8312515 DOI: 10.1111/acer.14633] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 04/16/2021] [Accepted: 05/11/2021] [Indexed: 12/24/2022]
Abstract
Background The developing hippocampus and cerebellum, unique among brain regions, exhibit a secondary surge in neurogenesis during the third trimester of pregnancy. Ethanol (EtOH) exposure during this period is results in a loss of tissue volume and associated neurobehavioral deficits. However, mechanisms that link EtOH exposure to teratology in these regions are not well understood. We therefore analyzed transcriptomic adaptations to EtOH exposure to identify mechanistic linkages. Methods Hippocampi and cerebella were microdissected at postnatal day (P)10, from control C57BL/6J mouse pups, and pups treated with 4 g/kg of EtOH from P4 to P9. RNA was isolated and RNA‐seq analysis was performed. We compared gene expression in EtOH‐ and vehicle‐treated control neonates and performed biological pathway‐overrepresentation analysis. Results While EtOH exposure resulted in the general induction of genes associated with the S‐phase of mitosis in both cerebellum and hippocampus, overall there was little overlap in differentially regulated genes and associated biological pathways between these regions. In cerebellum, EtOH additionally induced gene expression associated with the G2/M‐phases of the cell cycle and sonic hedgehog signaling, while in hippocampus, EtOH‐induced the pathways for ribosome biogenesis and protein translation. Moreover, EtOH inhibited the transcriptomic identities associated with inhibitory interneuron subpopulations in the hippocampus, while in the cerebellum there was a more pronounced inhibition of transcripts across multiple oligodendrocyte maturation stages. Conclusions These data indicate that during the delayed neurogenic period, EtOH may stimulate the cell cycle, but it otherwise results in widely divergent molecular effects in the hippocampus and cerebellum. Moreover, these data provide evidence for region‐ and cell‐type‐specific vulnerability, which may contribute to the pathogenic effects of developmental EtOH exposure.
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Affiliation(s)
- Marisa R Pinson
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center, Bryan, TX, USA
| | - Kalee N Holloway
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - James C Douglas
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Cynthia J M Kane
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Rajesh C Miranda
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center, Bryan, TX, USA
| | - Paul D Drew
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA.,Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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13
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Boschen KE, Ptacek TS, Berginski ME, Simon JM, Parnell SE. Transcriptomic analyses of gastrulation-stage mouse embryos with differential susceptibility to alcohol. Dis Model Mech 2021; 14:dmm049012. [PMID: 34137816 PMCID: PMC8246266 DOI: 10.1242/dmm.049012] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 05/12/2021] [Indexed: 12/28/2022] Open
Abstract
Genetics are a known contributor to differences in alcohol sensitivity in humans with fetal alcohol spectrum disorders (FASDs) and in animal models. Our study profiled gene expression in gastrulation-stage embryos from two commonly used, genetically similar mouse substrains, C57BL/6J (6J) and C57BL/6NHsd (6N), that differ in alcohol sensitivity. First, we established normal gene expression patterns at three finely resolved time points during gastrulation and developed a web-based interactive tool. Baseline transcriptional differences across strains were associated with immune signaling. Second, we examined the gene networks impacted by alcohol in each strain. Alcohol caused a more pronounced transcriptional effect in the 6J versus 6N mice, matching the increased susceptibility of the 6J mice. The 6J strain exhibited dysregulation of pathways related to cell death, proliferation, morphogenic signaling and craniofacial defects, while the 6N strain showed enrichment of hypoxia and cellular metabolism pathways. These datasets provide insight into the changing transcriptional landscape across mouse gastrulation, establish a valuable resource that enables the discovery of candidate genes that may modify alcohol susceptibility that can be validated in humans, and identify novel pathogenic mechanisms of alcohol. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Karen E. Boschen
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Travis S. Ptacek
- Carolina Institute for Developmental Disabilities, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- UNC Neuroscience Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Matthew E. Berginski
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jeremy M. Simon
- Carolina Institute for Developmental Disabilities, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- UNC Neuroscience Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Scott E. Parnell
- Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Carolina Institute for Developmental Disabilities, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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14
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Salem NA, Mahnke AH, Konganti K, Hillhouse AE, Miranda RC. Cell-type and fetal-sex-specific targets of prenatal alcohol exposure in developing mouse cerebral cortex. iScience 2021; 24:102439. [PMID: 33997709 PMCID: PMC8105653 DOI: 10.1016/j.isci.2021.102439] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 03/07/2021] [Accepted: 04/13/2021] [Indexed: 11/17/2022] Open
Abstract
Prenatal alcohol exposure (PAE) results in cerebral cortical dysgenesis. Single-cell RNA sequencing was performed on murine fetal cerebral cortical cells from six timed pregnancies, to decipher persistent cell- and sex-specific effects of an episode of PAE during early neurogenesis. We found, in an analysis of 38 distinct neural subpopulations across 8 lineage subtypes, that PAE altered neural maturation and cell cycle and disrupted gene co-expression networks. Whereas most differentially regulated genes were inhibited, particularly in females, PAE also induced sex-independent neural expression of fetal hemoglobin, a presumptive epigenetic stress adaptation. PAE inhibited Bcl11a, Htt, Ctnnb1, and other upstream regulators of differentially expressed genes and inhibited several autism-linked genes, suggesting that neurodevelopmental disorders share underlying mechanisms. PAE females exhibited neural loss of X-inactivation, with correlated activation of autosomal genes and evidence for spliceosome dysfunction. Thus, episodic PAE persistently alters the developing neural transcriptome, contributing to sex- and cell-type-specific teratology. The neurogenic murine fetal cortex contains about 33 distinct cell subtypes Prenatal Alcohol Exposure (PAE) resulted in sex-specific alterations in developmental trajectory and cell cycle PAE females exhibited neural loss of X-inactivation and spliceosomal dysfunction PAE induced sex-independent neural expression of fetal hemoglobin gene transcripts
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Affiliation(s)
- Nihal A. Salem
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Medical Research and Education Building, 8447 Riverside Parkway, Bryan, TX 77807-3260, USA
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX, USA
| | - Amanda H. Mahnke
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Medical Research and Education Building, 8447 Riverside Parkway, Bryan, TX 77807-3260, USA
- Women's Health in Neuroscience Program, Texas A&M University Health Science Center, Bryan, TX, USA
| | - Kranti Konganti
- Texas A&M Institute for Genome Sciences and Society, Texas A&M University, College Station, TX 77843, USA
| | - Andrew E. Hillhouse
- Texas A&M Institute for Genome Sciences and Society, Texas A&M University, College Station, TX 77843, USA
| | - Rajesh C. Miranda
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Medical Research and Education Building, 8447 Riverside Parkway, Bryan, TX 77807-3260, USA
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX, USA
- Women's Health in Neuroscience Program, Texas A&M University Health Science Center, Bryan, TX, USA
- Corresponding author
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15
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Boschen KE, Ptacek TS, Simon JM, Parnell SE. Transcriptome-Wide Regulation of Key Developmental Pathways in the Mouse Neural Tube by Prenatal Alcohol Exposure. Alcohol Clin Exp Res 2020; 44:1540-1550. [PMID: 32557641 DOI: 10.1111/acer.14389] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 05/02/2020] [Accepted: 05/31/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND Early gestational alcohol exposure is associated with severe craniofacial and CNS dysmorphologies and behavioral abnormalities during adolescence and adulthood. Alcohol exposure during the formation of the neural tube (gestational day [GD] 8 to 10 in mice; equivalent to4th week of human pregnancy) disrupts development of ventral midline brain structures such as the pituitary, septum, and ventricles. This study identifies transcriptomic changes in the rostroventral neural tube (RVNT), the region of the neural tube that gives rise to the midline structures sensitive to alcohol exposure during neurulation. METHODS Female C57BL/6J mice were administered 2 doses of alcohol (2.9 g/kg) or vehicle 4 hours apart on GD 9.0. The RVNTs of embryos were collected 6 or 24 hours after the first dose and processed for RNA-seq. RESULTS Six hours following GD 9.0 alcohol exposure (GD 9.25), over 2,300 genes in the RVNT were determined to be differentially regulated by alcohol. Enrichment analysis determined that PAE affected pathways related to cell proliferation, p53 signaling, ribosome biogenesis, and immune activation. In addition, over 100 genes involved in primary cilia formation and function and regulation of morphogenic pathways were altered 6 hours after alcohol exposure. The changes to gene expression were largely transient, as only 91 genes identified as differentially regulated by prenatal alcohol at GD 10 (24 hours postexposure). Functionally, the differentially regulated genes at GD 10 were related to organogenesis and cell migration. CONCLUSIONS These data give a comprehensive view of the changing landscape of the embryonic transcriptome networks in regions of the neural tube that give rise to brain structures impacted by a neurulation-stage alcohol exposure. Identification of gene networks dysregulated by alcohol will help elucidate the pathogenic mechanisms of alcohol's actions.
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Affiliation(s)
- Karen E Boschen
- From the Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Travis S Ptacek
- Carolina Institute for Developmental Disabilities, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jeremy M Simon
- Carolina Institute for Developmental Disabilities, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Scott E Parnell
- From the Bowles Center for Alcohol Studies, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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16
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Bogenpohl JW, Smith ML, Farris SP, Dumur CI, Lopez MF, Becker HC, Grant KA, Miles MF. Cross-Species Co-analysis of Prefrontal Cortex Chronic Ethanol Transcriptome Responses in Mice and Monkeys. Front Mol Neurosci 2019; 12:197. [PMID: 31456662 PMCID: PMC6701453 DOI: 10.3389/fnmol.2019.00197] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/30/2019] [Indexed: 12/20/2022] Open
Abstract
Despite recent extensive genomic and genetic studies on behavioral responses to ethanol, relatively few new therapeutic targets for the treatment of alcohol use disorder have been validated. Here, we describe a cross-species genomic approach focused on identifying gene networks associated with chronic ethanol consumption. To identify brain mechanisms underlying a chronic ethanol consumption phenotype highly relevant to human alcohol use disorder, and to elucidate potential future therapeutic targets, we conducted a genomic study in a non-human primate model of chronic open-access ethanol consumption. Microarray analysis of RNA expression in anterior cingulate and subgenual cortices from rhesus macaques was performed across multiple cohorts of animals. Gene networks correlating with ethanol consumption or showing enrichment for ethanol-regulated genes were identified, as were major ethanol-related hub genes within these networks. A subsequent consensus module analysis was used to co-analyze monkey data with expression data from a chronic intermittent ethanol vapor-exposure and consumption model in C57BL/6J mice. Ethanol-related gene networks conserved between primates and rodents were enriched for genes involved in discrete biological functions, including; myelination, synaptic transmission, chromatin modification, Golgi apparatus function, translation, cellular respiration, and RNA processing. The myelin-related network, in particular, showed strong correlations with ethanol consumption behavior and displayed marked network reorganization between control and ethanol-drinking animals. Further bioinformatics analysis revealed that these networks also showed highly significant overlap with other ethanol-regulated gene sets. Altogether, these studies provide robust primate and rodent cross-species validation of gene networks associated with chronic ethanol consumption. Our results also suggest potential novel focal points for future therapeutic interventions in alcohol use disorder.
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Affiliation(s)
- James W Bogenpohl
- Department of Molecular Biology and Chemistry, Christopher Newport University, Newport News, VA, United States
| | - Maren L Smith
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA, United States
| | - Sean P Farris
- Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX, United States
| | - Catherine I Dumur
- Aurora Diagnostics-Sonic Healthcare, Bernhardt Laboratories, Jacksonville, FL, United States
| | - Marcelo F Lopez
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States
| | - Howard C Becker
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, United States
| | - Kathleen A Grant
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR, United States.,Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, United States
| | - Michael F Miles
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA, United States.,Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, United States.,Department of Neurology, Virginia Commonwealth University, Richmond, VA, United States.,VCU Alcohol Research Center, Virginia Commonwealth University, Richmond, VA, United States
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17
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Flentke GR, Baulch J, Berres ME, Garic A, Smith SM. Alcohol-mediated calcium signals dysregulate pro-survival Snai2/PUMA/Bcl2 networks to promote p53-mediated apoptosis in avian neural crest progenitors. Birth Defects Res 2019; 111:686-699. [PMID: 31021056 PMCID: PMC7017393 DOI: 10.1002/bdr2.1508] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/27/2019] [Accepted: 03/28/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND Prenatal alcohol exposure causes distinctive craniofacial anomalies that arise, in part, from the apoptotic elimination of neural crest (NC) progenitors that form the face. This vulnerability of NC to alcohol is puzzling as they normally express the transcriptional repressor Snail1/2 (in chick Snai2), which suppresses apoptosis and promotes their migration. Here, we investigate alcohol's impact upon Snai2 function. METHODS Chick cranial NC cells were treated with acute alcohol (52 mM, 2 hr). We evaluated NC migration, gene expression, proliferation, and apoptosis thereafter. RESULTS Transient alcohol exposure induced Snai2 (191% ± 23%; p = .003) and stimulated NC migration (p = .0092). An alcohol-induced calcium transient mediated this Snai2 induction, and BAPTA-AM blocked whereas ionomycin mimicked these pro-migratory effects. Alcohol suppressed CyclinD1 protein content (59.1 ± 12%, p = .007) and NC proliferation (19.7 ± 5.8%, p < .001), but these Snai2-enriched cells still apoptosed in response to alcohol. This was explained because alcohol induced p53 (198 ± 29%, p = .023), and the p53 antagonist pifithrin-α prevented their apoptosis. Moreover, alcohol counteracted Snai2's pro-survival signals, and Bcl2 was repressed (68.5 ± 6.0% of controls, p = .016) and PUMA was not induced, while ATM (1.32-fold, p = .01) and PTEN (1.30-fold, p = .028) were elevated. CONCLUSIONS Alcohol's calcium transient uncouples the Snai2/p53 regulatory loop that normally prevents apoptosis during EMT. This represents a novel pathway in alcohol's neurotoxicity, and complements demonstrations that alcohol suppresses PUMA in mouse NC. We propose that the NCs migratory behavior, and their requirement for Snai2/p53 co-expression, makes them vulnerable to stressors that dysregulate Snai2/p53 interactions, such as alcohol.
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Affiliation(s)
- George R. Flentke
- Nutrition Research Institute, Dept. Nutrition, University of North Carolina at Chapel Hill, Kannapolis NC 28081
- Dept. Nutritional Sciences, University of Wisconsin-Madison, Madison WI 53706
| | - Joshua Baulch
- Nutrition Research Institute, Dept. Nutrition, University of North Carolina at Chapel Hill, Kannapolis NC 28081
| | - Mark E. Berres
- Dept. Nutritional Sciences, University of Wisconsin-Madison, Madison WI 53706
| | - Ana Garic
- Dept. Nutritional Sciences, University of Wisconsin-Madison, Madison WI 53706
| | - Susan M. Smith
- Nutrition Research Institute, Dept. Nutrition, University of North Carolina at Chapel Hill, Kannapolis NC 28081
- Dept. Nutritional Sciences, University of Wisconsin-Madison, Madison WI 53706
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18
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Al-Shaer AE, Flentke GR, Berres ME, Garic A, Smith SM. Exon level machine learning analyses elucidate novel candidate miRNA targets in an avian model of fetal alcohol spectrum disorder. PLoS Comput Biol 2019; 15:e1006937. [PMID: 30973878 PMCID: PMC6478348 DOI: 10.1371/journal.pcbi.1006937] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 04/23/2019] [Accepted: 03/11/2019] [Indexed: 12/20/2022] Open
Abstract
Gestational alcohol exposure causes fetal alcohol spectrum disorder (FASD) and is a prominent cause of neurodevelopmental disability. Whole transcriptome sequencing (RNA-Seq) offer insights into mechanisms underlying FASD, but gene-level analysis provides limited information regarding complex transcriptional processes such as alternative splicing and non-coding RNAs. Moreover, traditional analytical approaches that use multiple hypothesis testing with a false discovery rate adjustment prioritize genes based on an adjusted p-value, which is not always biologically relevant. We address these limitations with a novel approach and implemented an unsupervised machine learning model, which we applied to an exon-level analysis to reduce data complexity to the most likely functionally relevant exons, without loss of novel information. This was performed on an RNA-Seq paired-end dataset derived from alcohol-exposed neural fold-stage chick crania, wherein alcohol causes facial deficits recapitulating those of FASD. A principal component analysis along with k-means clustering was utilized to extract exons that deviated from baseline expression. This identified 6857 differentially expressed exons representing 1251 geneIDs; 391 of these genes were identified in a prior gene-level analysis of this dataset. It also identified exons encoding 23 microRNAs (miRNAs) having significantly differential expression profiles in response to alcohol. We developed an RDAVID pipeline to identify KEGG pathways represented by these exons, and separately identified predicted KEGG pathways targeted by these miRNAs. Several of these (ribosome biogenesis, oxidative phosphorylation) were identified in our prior gene-level analysis. Other pathways are crucial to facial morphogenesis and represent both novel (focal adhesion, FoxO signaling, insulin signaling) and known (Wnt signaling) alcohol targets. Importantly, there was substantial overlap between the exomes themselves and the predicted miRNA targets, suggesting these miRNAs contribute to the gene-level expression changes. Our novel application of unsupervised machine learning in conjunction with statistical analyses facilitated the discovery of signaling pathways and miRNAs that inform mechanisms underlying FASD.
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Affiliation(s)
- Abrar E. Al-Shaer
- Nutrition Research Institute, Department of Nutrition, University of North Carolina at Chapel Hill, Kannapolis, North Carolina, United States of America
| | - George R. Flentke
- Nutrition Research Institute, Department of Nutrition, University of North Carolina at Chapel Hill, Kannapolis, North Carolina, United States of America
| | - Mark E. Berres
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Ana Garic
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Susan M. Smith
- Nutrition Research Institute, Department of Nutrition, University of North Carolina at Chapel Hill, Kannapolis, North Carolina, United States of America
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19
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Hetman M, Slomnicki LP. Ribosomal biogenesis as an emerging target of neurodevelopmental pathologies. J Neurochem 2018; 148:325-347. [PMID: 30144322 DOI: 10.1111/jnc.14576] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 08/15/2018] [Accepted: 08/21/2018] [Indexed: 12/17/2022]
Abstract
Development of the nervous system is carried out by complex gene expression programs that are regulated at both transcriptional and translational level. In addition, quality control mechanisms such as the TP53-mediated apoptosis or neuronal activity-stimulated survival ensure successful neurogenesis and formation of functional circuitries. In the nucleolus, production of ribosomes is essential for protein synthesis. In addition, it participates in chromatin organization and regulates the TP53 pathway via the ribosomal stress response. Its tight regulation is required for maintenance of genomic integrity. Mutations in several ribosomal components and trans-acting ribosomal biogenesis factors result in neurodevelopmental syndromes that present with microcephaly, autism, intellectual deficits and/or progressive neurodegeneration. Furthermore, ribosomal biogenesis is perturbed by exogenous factors that disrupt neurodevelopment including alcohol or Zika virus. In this review, we present recent literature that argues for a role of dysregulated ribosomal biogenesis in pathogenesis of various neurodevelopmental syndromes. We also discuss potential mechanisms through which such dysregulation may lead to cellular pathologies of the developing nervous system including insufficient proliferation and/or loss of neuroprogenitors cells, apoptosis of immature neurons, altered neuronal morphogenesis, and neurodegeneration.
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Affiliation(s)
- Michal Hetman
- Departments of Neurological Surgery, Kentucky Spinal Cord Injury Research Center, Louisville, Kentucky, USA.,Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky, USA
| | - Lukasz P Slomnicki
- Departments of Neurological Surgery, Kentucky Spinal Cord Injury Research Center, Louisville, Kentucky, USA
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20
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A Cyclin E Centered Genetic Network Contributes to Alcohol-Induced Variation in Drosophila Development. G3-GENES GENOMES GENETICS 2018; 8:2643-2653. [PMID: 29871898 PMCID: PMC6071605 DOI: 10.1534/g3.118.200260] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Prenatal exposure to ethanol causes a wide range of adverse physiological, behavioral and cognitive consequences. However, identifying allelic variants and genetic networks associated with variation in susceptibility to prenatal alcohol exposure is challenging in human populations, since time and frequency of exposure and effective dose cannot be determined quantitatively and phenotypic manifestations are diverse. Here, we harnessed the power of natural variation in the Drosophila melanogaster Genetic Reference Panel (DGRP) to identify genes and genetic networks associated with variation in sensitivity to developmental alcohol exposure. We measured development time from egg to adult and viability of 201 DGRP lines reared on regular or ethanol- supplemented medium and identified polymorphisms associated with variation in susceptibility to developmental ethanol exposure. We also documented genotype-dependent variation in sensorimotor behavior after developmental exposure to ethanol using the startle response assay in a subset of 39 DGRP lines. Genes associated with development, including development of the nervous system, featured prominently among genes that harbored variants associated with differential sensitivity to developmental ethanol exposure. Many of them have human orthologs and mutational analyses and RNAi targeting functionally validated a high percentage of candidate genes. Analysis of genetic interaction networks identified Cyclin E (CycE) as a central, highly interconnected hub gene. Cyclin E encodes a protein kinase associated with cell cycle regulation and is prominently expressed in ovaries. Thus, exposure to ethanol during development of Drosophila melanogaster might serve as a genetic model for translational studies on fetal alcohol spectrum disorder.
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21
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Flentke GR, Smith SM. The avian embryo as a model for fetal alcohol spectrum disorder. Biochem Cell Biol 2017; 96:98-106. [PMID: 29024604 DOI: 10.1139/bcb-2017-0205] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Prenatal alcohol exposure (PAE) remains a leading preventable cause of structural birth defects and permanent neurodevelopmental disability. The chicken (Gallus gallus domesticus) is a powerful embryological research model, and was possibly the first in which the teratogenicity of alcohol was demonstrated. Pharmacologically relevant exposure to alcohol in the range of 20-70 mmol/L (20-80 mg/egg) disrupt the growth of chicken embryos, morphogenesis, and behavior, and the resulting phenotypes strongly parallel those of mammalian models. The avian embryo's direct accessibility has enabled novel insights into the teratogenic mechanisms of alcohol. These include the contribution of IGF1 signaling to growth suppression, the altered flow dynamics that reshape valvuloseptal morphogenesis and mediate its cardiac teratogenicity, and the suppression of Wnt and Shh signals thereby disrupting the migration, expansion, and survival of the neural crest, and underlie its characteristic craniofacial deficits. The genetic diversity within commercial avian strains has enabled the identification of unique loci, such as ribosome biogenesis, that modify vulnerability to alcohol. This venerable research model is equally relevant for the future, as the application of technological advances including CRISPR, optogenetics, and biophotonics to the embryo's ready accessibility creates a unique model in which investigators can manipulate and monitor the embryo in real-time to investigate the effect of alcohol on cell fate.
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Affiliation(s)
- George R Flentke
- UNC-Nutrition Research Institute and Department of Nutrition, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA.,UNC-Nutrition Research Institute and Department of Nutrition, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA
| | - Susan M Smith
- UNC-Nutrition Research Institute and Department of Nutrition, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA.,UNC-Nutrition Research Institute and Department of Nutrition, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA
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22
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Berres ME, Garic A, Flentke GR, Smith SM. Transcriptome Profiling Identifies Ribosome Biogenesis as a Target of Alcohol Teratogenicity and Vulnerability during Early Embryogenesis. PLoS One 2017; 12:e0169351. [PMID: 28046103 PMCID: PMC5207668 DOI: 10.1371/journal.pone.0169351] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 12/15/2016] [Indexed: 01/05/2023] Open
Abstract
Fetal alcohol spectrum disorder (FASD) is a leading cause of neurodevelopmental disability. Individuals with FASD may exhibit a characteristic facial appearance that has diagnostic utility. The mechanism by which alcohol disrupts craniofacial development is incompletely understood, as are the genetic factors that can modify individual alcohol vulnerability. Using an established avian model, we characterized the cranial transcriptome in response to alcohol to inform the mechanism underlying these cells’ vulnerability. Gallus gallus embryos having 3–6 somites were exposed to 52 mM alcohol and the cranial transcriptomes were sequenced thereafter. A total of 3422 genes had significantly differential expression. The KEGG pathways with the greatest enrichment of differentially expressed gene clusters were Ribosome (P = 1.2 x 10−17, 67 genes), Oxidative Phosphorylation (P = 4.8 x 10−12, 60 genes), RNA Polymerase (P = 2.2 x 10−3, 15 genes) and Spliceosome (P = 2.6 x 10−2, 39 genes). The preponderance of transcripts in these pathways were repressed in response to alcohol. These same gene clusters also had the greatest altered representation in our previous comparison of neural crest populations having differential vulnerability to alcohol-induced apoptosis. Comparison of differentially expressed genes in alcohol-exposed (3422) and untreated, alcohol-vulnerable (1201) transcriptomes identified 525 overlapping genes of which 257 have the same direction of transcriptional change. These included 36 ribosomal, 25 oxidative phosphorylation and 7 spliceosome genes. Using a functional approach in zebrafish, partial knockdown of ribosomal proteins zrpl11, zrpl5a, and zrps3a individually heightened vulnerability to alcohol-induced craniofacial deficits and increased apoptosis. In humans, haploinsufficiency of several of the identified ribosomal proteins are causative in craniofacial dysmorphologies such as Treacher Collins Syndrome and Diamond-Blackfan Anemia. This work suggests ribosome biogenesis may be a novel target mediating alcohol’s damage to developing neural crest. Our findings are consistent with observations that gene-environment interactions contribute to vulnerability in FASD.
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Affiliation(s)
- Mark E. Berres
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Ana Garic
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - George R. Flentke
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Susan M. Smith
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail: ,
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23
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Eberhart JK, Parnell SE. The Genetics of Fetal Alcohol Spectrum Disorders. Alcohol Clin Exp Res 2016; 40:1154-65. [PMID: 27122355 DOI: 10.1111/acer.13066] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/04/2016] [Indexed: 12/29/2022]
Abstract
The term "fetal alcohol spectrum disorders" (FASD) defines the full range of ethanol (EtOH)-induced birth defects. Numerous variables influence the phenotypic outcomes of embryonic EtOH exposure. Among these variables, genetics appears to play an important role, yet our understanding of the genetic predisposition to FASD is still in its infancy. We review the current literature that relates to the genetics of FASD susceptibility and gene-EtOH interactions. Where possible, we comment on potential mechanisms of reported gene-EtOH interactions. Early indications of genetic sensitivity to FASD came from human and animal studies using twins or inbred strains, respectively. These analyses prompted searches for susceptibility loci involved in EtOH metabolism and analyses of candidate loci, based on phenotypes observed in FASD. More recently, genetic screens in animal models have provided an additional insight into the genetics of FASD. Understanding FASD requires that we understand the many factors influencing phenotypic outcome following embryonic EtOH exposure. We are gaining ground on understanding some of the genetics behind FASD, yet much work remains to be carried out. Coordinated analyses using human patients and animal models are likely to be highly fruitful in uncovering the genetics behind FASD.
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Affiliation(s)
- Johann K Eberhart
- Department of Molecular Biosciences, Institute for Cell and Molecular Biology, Institute for Neuroscience, Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, Texas
| | - Scott E Parnell
- Bowles Center for Alcohol Studies, Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina
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24
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Perez DM, Richards MP, Parker RS, Berres ME, Wright AT, Sifri M, Sadler NC, Tatiyaborworntham N, Li N. Role of Cytochrome P450 Hydroxylase in the Decreased Accumulation of Vitamin E in Muscle from Turkeys Compared to that from Chickens. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2016; 64:671-680. [PMID: 26653675 PMCID: PMC4753779 DOI: 10.1021/acs.jafc.5b05433] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Turkeys and chickens reared to 5 weeks of age and fed diets with feedstuffs low in endogenous tocopherols were examined. Treatments included feed supplemented with RRR (natural source vitamin E) alpha tocopheryl acetate (AcT, 35 mg/kg feed) and all-racemic (synthetic vitamin E) AcT (10 and 58 mg/kg feed). Alpha tocopherol hydroxylase activity was greater in liver microsomes prepared from turkeys compared to that from chickens (p < 0.01). Alpha and gamma tocopherol metabolites were higher in turkey bile than in chicken when assessing the RRR AcT diet and the all-racemic AcT diet at 58 mg/kg feed (p < 0.01). Turkey cytochrome P450 2C29 was increased relative to its chicken ortholog on the basis of RNA-Seq transcript abundance (p < 0.001) and activity-based protein profiling (p < 0.01) of liver tissue. Alpha tocopherol concentrations in plasma, liver, and muscle from turkey were lower than the respective tissues from chicken (p < 0.05). Lipid oxidation was greater in turkey thigh than in chicken (p < 0.05). These results suggest that elevated tocopherol metabolism by cytochrome P450 hydroxylase(s) in turkeys contributes to the decreased accumulation of alpha tocopherol in turkey tissues compared to that of chickens.
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Affiliation(s)
- Dale M. Perez
- Department of Animal Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Mark P. Richards
- Department of Animal Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Robert S. Parker
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14850, United States
| | - Mark E. Berres
- Department of Animal Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Aaron T. Wright
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Mamduh Sifri
- Animal Nutrition Division, Archer Daniels Midland Co., Quincy, Illinois 62301, United States
| | - Natalie C Sadler
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | | | - Na Li
- Department of Animal Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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25
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Kiecker C. The chick embryo as a model for the effects of prenatal exposure to alcohol on craniofacial development. Dev Biol 2016; 415:314-325. [PMID: 26777098 DOI: 10.1016/j.ydbio.2016.01.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 10/28/2015] [Accepted: 01/13/2016] [Indexed: 12/15/2022]
Abstract
Prenatal exposure to ethanol results in fetal alcohol spectrum disorder (FASD), a syndrome characterised by a broad range of clinical manifestations including craniofacial dysmorphologies and neurological defects. The characterisation of the mechanisms by which ethanol exerts its teratogenic effects is difficult due to the pleiotropic nature of its actions. Different experimental model systems have been employed to investigate the aetiology of FASD. Here, I will review studies using these different model organisms that have helped to elucidate how ethanol causes the craniofacial abnormalities characteristic of FASD. In these studies, ethanol was found to impair the prechordal plate-an important embryonic signalling centre-during gastrulation and to negatively affect the induction, migration and survival of the neural crest, a cell population that generates the cartilage and most of the bones of the skull. At the cellular level, ethanol appears to inhibit Sonic hedgehog signalling, alter levels of retionoic acid activity, trigger a Ca(2+)-CamKII-dependent pathway that antagonises WNT signalling, affect cytoskeletal dynamics and increase oxidative stress. Embryos of the domestic chick Gallus gallus domesticus have played a central role in developing a working model for the effects of ethanol on craniofacial development because they are easily accessible and because key steps in craniofacial development are particularly well established in the avian embryo. I will finish this review by highlighting some potential future avenues of fetal alcohol research.
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Affiliation(s)
- Clemens Kiecker
- MRC Centre for Developmental Neurobiology, 4th Floor, Hodgkin Building, Guy's Hospital Campus, King's College London, UK.
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26
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Smith SM, Garic A, Flentke GR, Berres ME. Neural crest development in fetal alcohol syndrome. ACTA ACUST UNITED AC 2014; 102:210-20. [PMID: 25219761 DOI: 10.1002/bdrc.21078] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 08/22/2014] [Indexed: 01/24/2023]
Abstract
Fetal alcohol spectrum disorder (FASD) is a leading cause of neurodevelopmental disability. Some affected individuals possess distinctive craniofacial deficits, but many more lack overt facial changes. An understanding of the mechanisms underlying these deficits would inform their diagnostic utility. Our understanding of these mechanisms is challenged because ethanol lacks a single receptor when redirecting cellular activity. This review summarizes our current understanding of how ethanol alters neural crest development. Ample evidence shows that ethanol causes the "classic" fetal alcohol syndrome (FAS) face (short palpebral fissures, elongated upper lip, deficient philtrum) because it suppresses prechordal plate outgrowth, thereby reducing neuroectoderm and neural crest induction and causing holoprosencephaly. Prenatal alcohol exposure (PAE) at premigratory stages elicits a different facial appearance, indicating FASD may represent a spectrum of facial outcomes. PAE at this premigratory period initiates a calcium transient that activates CaMKII and destabilizes transcriptionally active β-catenin, thereby initiating apoptosis within neural crest populations. Contributing to neural crest vulnerability are their low antioxidant responses. Ethanol-treated neural crest produce reactive oxygen species and free radical scavengers attenuate their production and prevent apoptosis. Ethanol also significantly impairs neural crest migration, causing cytoskeletal rearrangements that destabilize focal adhesion formation; their directional migratory capacity is also lost. Genetic factors further modify vulnerability to ethanol-induced craniofacial dysmorphology and include genes important for neural crest development, including shh signaling, PDFGA, vangl2, and ribosomal biogenesis. Because facial and brain development are mechanistically and functionally linked, research into ethanol's effects on neural crest also informs our understanding of ethanol's CNS pathologies.
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Affiliation(s)
- Susan M Smith
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, 53706
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Smith SM, Garic A, Berres ME, Flentke GR. Genomic factors that shape craniofacial outcome and neural crest vulnerability in FASD. Front Genet 2014; 5:224. [PMID: 25147554 PMCID: PMC4124534 DOI: 10.3389/fgene.2014.00224] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 06/27/2014] [Indexed: 12/01/2022] Open
Abstract
Prenatal alcohol exposure (PAE) causes distinctive facial characteristics in some pregnancies and not others; genetic factors may contribute to this differential vulnerability. Ethanol disrupts multiple events of neural crest development, including induction, survival, migration, and differentiation. Animal models and genomic approaches have substantially advanced our understanding of the mechanisms underlying these facial changes. PAE during gastrulation produces craniofacial changes corresponding with human fetal alcohol syndrome. These result because PAE reduces prechordal plate extension and suppresses sonic hedgehog, leading to holoprosencephaly and malpositioned facial primordia. Haploinsufficiency in sonic hedgehog signaling increases vulnerability to facial deficits and may influence some PAE pregnancies. In contrast, PAE during early neurogenesis produces facial hypoplasia, preceded by neural crest reductions due to significant apoptosis. Factors mediating this apoptosis include intracellular calcium mobilization, elevated reactive oxygen species, and loss of trophic support from β-catenin/calcium, sonic hedgehog, and mTOR signaling. Genome-wide SNP analysis links PDGFRA with facial outcomes in human PAE. Multiple genomic-level comparisons of ethanol-sensitive and – resistant early embryos, in both mouse and chick, independently identify common candidate genes that may potentially modify craniofacial vulnerability, including ribosomal proteins, proteosome, RNA splicing, and focal adhesion. In summary, research using animal models with genome-level differences in ethanol vulnerability, as well as targeted loss-and gain-of-function mutants, has clarified the mechanisms mediating craniofacial change in PAE. The findings additionally suggest that craniofacial deficits may represent a gene–ethanol interaction for some affected individuals. Genetic-level changes may prime individuals toward greater sensitivity or resistance to ethanol’s neurotoxicity.
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Affiliation(s)
- Susan M Smith
- Department of Nutritional Sciences, University of Wisconsin-Madison Madison, WI, USA
| | - Ana Garic
- Department of Nutritional Sciences, University of Wisconsin-Madison Madison, WI, USA
| | - Mark E Berres
- Department of Animal Sciences, University of Wisconsin-Madison Madison, WI, USA
| | - George R Flentke
- Department of Nutritional Sciences, University of Wisconsin-Madison Madison, WI, USA
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