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Gopinathan G, Zhang X, Luan X, Diekwisch TGH. Changes in Hox Gene Chromatin Organization during Odontogenic Lineage Specification. Genes (Basel) 2023; 14:198. [PMID: 36672939 PMCID: PMC9859321 DOI: 10.3390/genes14010198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/06/2023] [Accepted: 01/09/2023] [Indexed: 01/13/2023] Open
Abstract
Craniofacial tissues comprise highly evolved organs characterized by a relative lack of expression in the HOX family transcription factors. In the present study, we sought to define the epigenetic events that limit HOX gene expression from undifferentiated neural crest cells to semi-differentiated odontogenic progenitors and to explore the effects of elevated levels of HOX. The ChIP-chip data demonstrated high levels of repressive H3K27me3 marks on the HOX gene promoters in ES and cranial neural crest cells when compared to the H3K4me3 marks, while the K4/K27 ratio was less repressive in the odontogenic progenitors, dental follicle, dental pulp, periodontal ligament fibroblasts, alveolar bone osteoblasts, and cementoblasts. The gene expression of multiple HOX genes, especially those from the HOXA and HOXB clusters, was significantly elevated and many times higher in alveolar bone cells than in the dental follicle cells. In addition, the HOX levels in the skeletal osteoblasts were many times higher in the trunk osteoblasts compared to the alveolar bone osteoblasts, and the repressive mark H3K27me3 promoter occupancy was substantially and significantly elevated in the alveolar bone osteoblasts when compared to the trunk osteoblasts. To explore the effect of elevated HOX levels in craniofacial neural crest cells, HOX expression was induced by transfecting cells with the Cdx4 transcription factor, resulting in a significant decrease in the mineralization markers, RUNX2, OSX, and OCN upon HOX elevation. Promoting HOX gene expression in developing teeth using the small molecule EZH2 inhibitor GSK126 resulted in an increased number of patterning events, supernumerary cusp formation, and increased Hoxa4 and Hoxb6 gene expression when compared to the controls. Together, these studies illustrate the profound effects of epigenetic regulatory events at all stages of the differentiation of craniofacial peripheral tissues from the neural crest, including lineage specification, tissue differentiation, and patterning.
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Affiliation(s)
- Gokul Gopinathan
- Center for Craniofacial Research and Diagnosis, Texas A&M University, Dallas, TX 75246, USA
| | - Xinmin Zhang
- Bioinforx Inc., 510 Charmany Dr#275a, Madison, WI 53719, USA
| | - Xianghong Luan
- Center for Craniofacial Research and Diagnosis, Texas A&M University, Dallas, TX 75246, USA
| | - Thomas G. H. Diekwisch
- Center for Craniofacial Research and Diagnosis, Texas A&M University, Dallas, TX 75246, USA
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Gur M, Bendelac-Kapon L, Shabtai Y, Pillemer G, Fainsod A. Reduced Retinoic Acid Signaling During Gastrulation Induces Developmental Microcephaly. Front Cell Dev Biol 2022; 10:844619. [PMID: 35372345 PMCID: PMC8967241 DOI: 10.3389/fcell.2022.844619] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 02/24/2022] [Indexed: 12/21/2022] Open
Abstract
Retinoic acid (RA) is a central signaling molecule regulating multiple developmental decisions during embryogenesis. Excess RA induces head malformations, primarily by expansion of posterior brain structures at the expense of anterior head regions, i.e., hindbrain expansion. Despite this extensively studied RA teratogenic effect, a number of syndromes exhibiting microcephaly, such as DiGeorge, Vitamin A Deficiency, Fetal Alcohol Syndrome, and others, have been attributed to reduced RA signaling. This causative link suggests a requirement for RA signaling during normal head development in all these syndromes. To characterize this novel RA function, we studied the involvement of RA in the early events leading to head formation in Xenopus embryos. This effect was mapped to the earliest RA biosynthesis in the embryo within the gastrula Spemann-Mangold organizer. Head malformations were observed when reduced RA signaling was induced in the endogenous Spemann-Mangold organizer and in the ectopic organizer of twinned embryos. Two embryonic retinaldehyde dehydrogenases, ALDH1A2 (RALDH2) and ALDH1A3 (RALDH3) are initially expressed in the organizer and subsequently mark the trunk and the migrating leading edge mesendoderm, respectively. Gene-specific knockdowns and CRISPR/Cas9 targeting show that RALDH3 is a key enzyme involved in RA production required for head formation. These observations indicate that in addition to the teratogenic effect of excess RA on head development, RA signaling also has a positive and required regulatory role in the early formation of the head during gastrula stages. These results identify a novel RA activity that concurs with its proposed reduction in syndromes exhibiting microcephaly.
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An adverse outcome pathway on the disruption of retinoic acid metabolism leading to developmental craniofacial defects. Toxicology 2021; 458:152843. [PMID: 34186166 DOI: 10.1016/j.tox.2021.152843] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/28/2021] [Accepted: 06/24/2021] [Indexed: 11/21/2022]
Abstract
Adverse outcome pathway (AOP) is a conceptual framework that links a molecular initiating event (MIE) via intermediate key events (KEs) with adverse effects (adverse outcomes, AO) relevant for risk assessment, through defined KE relationships (KERs). The aim of the present work is to describe a linear AOP, supported by experimental data, for skeletal craniofacial defects as the AO. This AO was selected in view of its relative high incidence in humans and the suspected relation to chemical exposure. We focused on inhibition of CYP26, a retinoic acid (RA) metabolizing enzyme, as MIE, based on robust previously published data. Conazoles were selected as representative stressors. Intermediate KEs are RA disbalance, aberrant HOX gene expression, disrupted specification, migration, and differentiation of neural crest cells, and branchial arch dysmorphology. We described the biological basis of the postulated events and conducted weight of evidence (WoE) assessments. The biological plausibility and the overall empirical evidence were assessed as high and moderate, respectively, the latter taking into consideration the moderate evidence for concordance of dose-response and temporal relationships. Finally, the essentiality assessment of the KEs, considered as high, supported the robustness of the presented AOP. This AOP, which appears of relevance to humans, thus contributes to mechanistic underpinning of selected test methods, thereby supporting their application in integrated new approach test methodologies and strategies and application in a regulatory context.
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Fainsod A, Bendelac-Kapon L, Shabtai Y. Fetal Alcohol Spectrum Disorder: Embryogenesis Under Reduced Retinoic Acid Signaling Conditions. Subcell Biochem 2020; 95:197-225. [PMID: 32297301 DOI: 10.1007/978-3-030-42282-0_8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Fetal Alcohol Spectrum Disorder (FASD) is a complex set of developmental malformations, neurobehavioral anomalies and mental disabilities induced by exposing human embryos to alcohol during fetal development. Several experimental models and a series of developmental and biochemical approaches have established a strong link between FASD and reduced retinoic acid (RA) signaling. RA signaling is involved in the regulation of numerous developmental decisions from patterning of the anterior-posterior axis, starting at gastrulation, to the differentiation of specific cell types within developing organs, to adult tissue homeostasis. Being such an important regulatory signal during embryonic development, mutations or environmental perturbations that affect the level, timing or location of the RA signal can induce multiple and severe developmental malformations. The evidence connecting human syndromes to reduced RA signaling is presented here and the resulting phenotypes are compared to FASD. Available data suggest that competition between ethanol clearance and RA biosynthesis is a major etiological component in FASD.
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Affiliation(s)
- Abraham Fainsod
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Ein Kerem, POB 12271, 9112102, Jerusalem, Israel.
| | - Liat Bendelac-Kapon
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Ein Kerem, POB 12271, 9112102, Jerusalem, Israel
| | - Yehuda Shabtai
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Ein Kerem, POB 12271, 9112102, Jerusalem, Israel
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5
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Battistoni M, Di Renzo F, Menegola E, Bois FY. Quantitative AOP based teratogenicity prediction for mixtures of azole fungicides. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.comtox.2019.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Petrelli B, Bendelac L, Hicks GG, Fainsod A. Insights into retinoic acid deficiency and the induction of craniofacial malformations and microcephaly in fetal alcohol spectrum disorder. Genesis 2019; 57:e23278. [DOI: 10.1002/dvg.23278] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 12/03/2018] [Accepted: 12/04/2018] [Indexed: 12/14/2022]
Affiliation(s)
- Berardino Petrelli
- Regenerative Medicine Program and the Department of Biochemistry & Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health SciencesUniversity of Manitoba Winnipeg Manitoba Canada
| | - Liat Bendelac
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel‐CanadaFaculty of Medicine, Hebrew University Jerusalem Israel
| | - Geoffrey G. Hicks
- Regenerative Medicine Program and the Department of Biochemistry & Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health SciencesUniversity of Manitoba Winnipeg Manitoba Canada
| | - Abraham Fainsod
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel‐CanadaFaculty of Medicine, Hebrew University Jerusalem Israel
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Živicová V, Lacina L, Mateu R, Smetana K, Kavková R, Krejčí ED, Grim M, Kvasilová A, Borský J, Strnad H, Hradilová M, Šáchová J, Kolář M, Dvořánková B. Analysis of dermal fibroblasts isolated from neonatal and child cleft lip and adult skin: Developmental implications on reconstructive surgery. Int J Mol Med 2017; 40:1323-1334. [PMID: 28901389 PMCID: PMC5627884 DOI: 10.3892/ijmm.2017.3128] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 08/21/2017] [Indexed: 01/12/2023] Open
Abstract
The nonsyndromic cleft is one of the most frequent congenital defects in humans. Clinical data demonstrated improved and almost scarless neonatal healing of reparative surgery. Based on our previous results on crosstalk between neonatal fibroblasts and adult keratinocytes, the present study focused on characterization of fibroblasts prepared from cleft lip tissue samples of neonates and older children, and compared them with samples isolated from normal adult skin (face and breast) and scars. Although subtle variances in expression profiles of children and neonates were observed, the two groups differed significantly from adult cells. Compared with adult cells, differences were observed in nestin and smooth muscle actin (SMA) expression at the protein and transcript level. Furthermore, fibroblast to myofibroblast differentiation drives effective wound healing and is largely regulated by the cytokine, transforming growth factor-β1 (TGF-β1). Dysregulation of the TGF-β signalling pathway, including low expression of the TGF-β receptor II, may contribute to reducing scarring in neonates. Fibroblasts of facial origin also exhibited age independent differences from the cells prepared from the breast, reflecting the origin of the facial cells from neural crest-based ectomesenchyme.
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Affiliation(s)
- Veronika Živicová
- Institute of Anatomy
- Department of Otorhinolaryngology, Head and Neck Surgery
| | - Lukáš Lacina
- Institute of Anatomy
- BIOCEV and
- Department of Dermatovenerology, The First Faculty of Medicine, Charles University, 121 08 Prague
| | | | | | | | | | | | | | - Jiří Borský
- Department of Otorhinolaryngology, The Second Faculty of Medicine, Charles University, 150 06 Prague
| | - Hynek Strnad
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic v.v.i., 142 20 Prague, Czech Republic
| | - Miluše Hradilová
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic v.v.i., 142 20 Prague, Czech Republic
| | - Jana Šáchová
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic v.v.i., 142 20 Prague, Czech Republic
| | - Michal Kolář
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic v.v.i., 142 20 Prague, Czech Republic
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8
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Biomarkers of teratogenesis: Suggestions from animal studies. Reprod Toxicol 2012; 34:180-5. [DOI: 10.1016/j.reprotox.2012.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 05/03/2012] [Accepted: 05/10/2012] [Indexed: 12/19/2022]
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9
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Are azole fungicides a teratogenic risk for human conceptus? Toxicol Lett 2010; 198:106-11. [DOI: 10.1016/j.toxlet.2010.07.005] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 07/02/2010] [Accepted: 07/06/2010] [Indexed: 11/23/2022]
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10
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Di Renzo F, Corsini E, Broccia M, Marinovich M, Galli C, Giavini E, Menegola E. Molecular mechanism of teratogenic effects induced by the fungicide triadimefon: Study of the expression of TGF-β mRNA and TGF-β and CRABPI proteins during rat in vitro development. Toxicol Appl Pharmacol 2009; 234:107-16. [DOI: 10.1016/j.taap.2008.09.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Revised: 09/29/2008] [Accepted: 09/29/2008] [Indexed: 10/21/2022]
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Oh J, Wang CJ, Poole M, Kim E, Davis RC, Nishimura I, Pae EK. A genome segment on mouse chromosome 12 determines maxillary growth. J Dent Res 2008; 86:1203-6. [PMID: 18037656 DOI: 10.1177/154405910708601212] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The primary and modifier genes that regulate normal maxillofacial development are unknown. Previous quantitative trait locus (QTL) analyses using the F2 progeny of 2 mouse strains, DBA/2J (short snout/wide face) and C57BL/6J (long snout/narrow face), revealed a significant logarithm-of-odds (LOD) score for snout length on mouse chromosome 12 at 44 centimorgan (cM). We further sought to validate this locus contributing to anterior-posterior dimensions of the upper mid-face at the D12Mit7 marker in a 44-centimorgan portion of chromosome 12. Congenic mice carrying introgressed DNA from DBA/2J on a C57BL/6J background were selected for submental vertex cephalometric imaging. Results confirmed QTLs, determining that short snout length (P < 0.05) and face width relative to snout length (P < 0.01) were present in the 44-cM region of chromosome 12. We conclude that one or more genes contributing to the shape of the maxillary complex are located near 44 cM of mouse chromosome 12.
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Affiliation(s)
- J Oh
- Section of Orthodontics, UCLA School of Dentistry, 43-091 Center for the Health Sciences, Box 951668, Los Angeles, CA 90095-1668, USA
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12
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Menegola E, Broccia ML, Di Renzo F, Giavini E. Postulated pathogenic pathway in triazole fungicide induced dysmorphogenic effects. Reprod Toxicol 2006; 22:186-95. [PMID: 16781842 DOI: 10.1016/j.reprotox.2006.04.008] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Revised: 04/10/2006] [Accepted: 04/10/2006] [Indexed: 11/19/2022]
Abstract
Triazole fungicides are used in medicine as well as in agricultural treatment of mycoses. The pharmacological mechanism is related to the inhibition of CYP enzymes involved in the formation of the fungal walls. A similar inhibition of human CYP enzymes has been suggested as the cause of triazole side effects in humans. An important role of some CYP isoforms (CYP26 isoforms) expressed during mammalian development is the catabolism of retinoic acid, a known morphogen in vertebrates and invertebrates. The adverse effects on morphogenesis, observed after exposure of mammalian, amphibian and ascidiacea, are compared to the reported effects of triazole in humans. The possible pathogenic pathway in triazole-related teratogenesis is discussed on the basis of different experimental approaches.
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Affiliation(s)
- Elena Menegola
- Department of Biology, University of Milan, via Celoria 26, 20133 Milan, Italy.
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13
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Mukhopadhyay P, Greene RM, Zacharias W, Weinrich MC, Singh S, Young WW, Pisano MM. Developmental gene expression profiling of mammalian, fetal orofacial tissue. ACTA ACUST UNITED AC 2005; 70:912-26. [PMID: 15578713 DOI: 10.1002/bdra.20095] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND The embryonic orofacial region is an excellent developmental paradigm that has revealed the centrality of numerous genes encoding proteins with diverse and important biological functions in embryonic growth and morphogenesis. DNA microarray technology presents an efficient means of acquiring novel and valuable information regarding the expression, regulation, and function of a panoply of genes involved in mammalian orofacial development. METHODS To identify differentially expressed genes during mammalian orofacial ontogenesis, the transcript profiles of GD-12, GD-13, and GD-14 murine orofacial tissue were compared utilizing GeneChip arrays from Affymetrix. Changes in gene expression were verified by TaqMan quantitative real-time PCR. Cluster analysis of the microarray data was done with the GeneCluster 2.0 Data Mining Tool and the GeneSpring software. RESULTS Expression of >50% of the approximately 12,000 genes and expressed sequence tags examined in this study was detected in GD-12, GD-13, and GD-14 murine orofacial tissues and the expression of several hundred genes was up- and downregulated in the developing orofacial tissue from GD-12 to GD-13, as well as from GD-13 to GD-14. Such differential gene expression represents changes in the expression of genes encoding growth factors and signaling molecules; transcription factors; and proteins involved in epithelial-mesenchymal interactions, extracellular matrix synthesis, cell adhesion, proliferation, differentiation, and apoptosis. Following cluster analysis of the microarray data, eight distinct patterns of gene expression during murine orofacial ontogenesis were selected for graphic presentation of gene expression patterns. CONCLUSIONS This gene expression profiling study identifies a number of potentially unique developmental participants and serves as a valuable aid in deciphering the complex molecular mechanisms crucial for mammalian orofacial development.
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Affiliation(s)
- Partha Mukhopadhyay
- University of Louisville Birth Defects Center, Department of Molecular Cellular and Craniofacial Biology, University of Louisville School of Dentistry, Louisville, Kentucky, KY 40292, USA
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Haw C, Sarma D, Ter Brugge K. Coexistence of Mandibular Arteriovenous Malformation and Cerebellar Arteriovenous Malformation. An Example of Cerebrofacial Arteriovenous Metameric Syndrome Type III. Interv Neuroradiol 2004; 9:71-4. [PMID: 20591306 DOI: 10.1177/159101990300900112] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2003] [Accepted: 01/20/2003] [Indexed: 11/15/2022] Open
Abstract
SUMMARY We describe a patient with cerebellar and mandibular arteriovenous malformations who initially presented with oral haemorrhage and then subsequently had a cerebellar haemorrhage. This is the second reported case of cerebrofacial arteriovenous metameric syndrome type III (CAMS III) in the literature and we discuss the role of homeobox genes in craniofacial development and angiogenesis.
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Affiliation(s)
- C Haw
- Diagnostic and Therapeutic Neuroradiology, Western Hospital, Toronto; Canada
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15
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Nishimura I, Drake TA, Lusis AJ, Lyons KM, Nadeau JH, Zernik J. ENU large-scale mutagenesis and quantitative trait linkage (QTL) analysis in mice: novel technologies for searching polygenetic determinants of craniofacial abnormalities. ACTA ACUST UNITED AC 2003; 14:320-30. [PMID: 14530301 DOI: 10.1177/154411130301400503] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Discrepancies in size and shape of the jaws are the underlying etiology in many orthodontic and orthognathic surgery patients. Genetic factors combined with environmental interactions have been postulated to play a causal or contributory role in these craniofacial abnormalities. Along with the soon-to-be-available complete human and mouse genomic sequence data, mouse mutants have become a valuable tool in the functional mapping of genes involved in the development of human maxillofacial dysmorphologies. We review two powerful methods in such efforts: N-ethyl-N-nitrosourea (ENU) large-scale mutagenesis and quantitative trait linkage (QTL) analysis. The former aims at producing a plethora of novel variants of particular trait(s), and ultimately mapping the point mutations responsible for the appearance of these new traits. In contrast, the latter applies intensive breeding and mapping techniques to identify multiple loci (and, subsequently, genes) contributing to the phenotypic difference between the tested strains. A prerequisite for either approach to studying variations in the traits of interest is the application of effective mouse cephalometric phenotype analysis and rapid DNA mapping techniques. These approaches will produce a wealth of new data on critical genes that influence the size and shape of the human face.
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Affiliation(s)
- Ichiro Nishimura
- The Jane and Jerry Weintraub Center for Reconstructive Biotechnology, Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, UCLA School of Dentistry, Box 951668, CHS B3-087, Los Angeles, CA 90095, USA.
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Morgan EA, Nguyen SB, Scott V, Stadler HS. Loss of Bmp7 and Fgf8 signaling in Hoxa13-mutant mice causes hypospadia. Development 2003; 130:3095-109. [PMID: 12783783 DOI: 10.1242/dev.00530] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In humans and mice, mutations in Hoxa13 cause malformation of limb and genitourinary (GU) regions. In males, one of the most common GU malformations associated with loss of Hoxa13 function is hypospadia, a condition defined by the poor growth and closure of the urethra and glans penis. By examining early signaling in the developing mouse genital tubercle, we show that Hoxa13 is essential for normal expression of Fgf8 and Bmp7 in the urethral plate epithelium. In Hoxa13(GFP)-mutant mice, hypospadias occur as a result of the combined loss of Fgf8 and Bmp7 expression in the urethral plate epithelium, as well as the ectopic expression of noggin (Nog) in the flanking mesenchyme. In vitro supplementation with Fgf8 restored proliferation in homozygous mutants to wild-type levels, suggesting that Fgf8 is sufficient to direct early proliferation of the developing genital tubercle. However, the closure defects of the distal urethra and glans can be attributed to a loss of apoptosis in the urethra, which is consistent with reduced Bmp7 expression in this region. Mice mutant for Hoxa13 also exhibit changes in androgen receptor expression, providing a developmental link between Hoxa13-associated hypospadias and those produced by antagonists to androgen signaling. Finally, a novel role for Hoxa13 in the vascularization of the glans penis is also identified.
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17
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Read RW, Burnstine M, Rowland JM, Zamir E, Rao NA. Rhabdomyomatous mesenchymal hamartoma of the eyelid: report of a case and literature review. Ophthalmology 2001; 108:798-804. [PMID: 11297501 DOI: 10.1016/s0161-6420(00)00638-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Abstract
PURPOSE To report a rare case of rhabdomyomatous mesenchymal hamartoma and to compare its features with those cases previously reported. DESIGN Interventional case report and literature review. INTERVENTION Complete ophthalmologic and systemic examinations followed by excisional biopsy and histopathologic examination. MAIN OUTCOME MEASURES Clinical examination features and histopathologic findings. RESULTS A 6-month-old Latino male presented with a congenital, elevated, smooth, flesh-colored right lower eyelid lesion. An ipsilateral right limbal dermoid and an upper eyelid coloboma were also present. Excisional biopsy of the eyelid lesion revealed randomly oriented mature striated muscle tissue with associated adipose tissue, blood vessels, pilosebaceous units, and peripheral nerves, findings consistent with rhabdomyomatous mesenchymal hamartoma. Of the 24 reported cases (including the current case), eight had associated congenital anomalies. CONCLUSIONS Although rhabdomyomatous mesenchymal hamartomas are rare and benign, they may be associated with other congenital anomalies and anomaly syndromes. As a result, we recommend systemic evaluation of patients diagnosed with this entity.
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Affiliation(s)
- R W Read
- Doheny Eye Institute, Keck School of Medicine at the University of Southern California, 1450 San Pablo Street, Los Angeles, CA 90033, USA
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18
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Altmann CR, Brivanlou AH. Neural patterning in the vertebrate embryo. INTERNATIONAL REVIEW OF CYTOLOGY 2001; 203:447-82. [PMID: 11131523 DOI: 10.1016/s0074-7696(01)03013-3] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The embryonic central nervous system (CNS) is patterned along its antero-posterior, dorsal-ventral, and left-right axes. Along the dorsal-ventral axis, cell fate determination occurs during and following neural tube closure and involves the action of two opposing signaling pathways: SHH ventrally from the notochord and BMP/GDF dorsally from the boundary of neural and nonneural ectoderm and later from the roof plate. In addition, Wnt and retinoic acid signaling have been shown to act in dorsal-ventral patterning; however, their roles are understood in less detail. Along the antero-posterior axis, signals divide the neural tube into four major divisions: forebrain, midbrain, hindbrain, and spinal cord, and these differences can be detected soon after the formation of the neural plate. The FGF, Wnt, and retinoic acid signaling pathways have been implicated in the caudalization of neural tissue. Boundaries of Hox gene expression are observed along the anteroposterior axis and have been suggested to be involved in establishing different identities in the hindbrain and spinal cord. Complex gene expression patterns in the brain suggest the development of neuromeres dividing the brain into different regions that are elaborated further during development. Patterning along the left-right axis occurs concurrently with antero-posterior and dorsal-ventral patterning during gastrulation. A leading candidate for initiating asymmetry is activin, which acts through Nodal and Lefty before any morphological differences are observed. The big challenge will be understanding how these diverse signaling pathways interact both temporally and spatially to generate the complex adult nervous system.
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Affiliation(s)
- C R Altmann
- The Rockefeller University, New York, New York 10021, USA
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21
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Nugent P, Greene RM. MSX-1 gene expression and regulation in embryonic palatal tissue. In Vitro Cell Dev Biol Anim 1998; 34:831-5. [PMID: 9870533 DOI: 10.1007/s11626-998-0038-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The palatal cleft seen in Msx-1 knock-out mice suggests a role for this gene in normal palate development. The cleft is presumed secondary to tooth and jaw malformations, since in situ hybridization suggests that Msx-1 mRNA is not highly expressed in developing palatal tissue. In this study we demonstrate, by Northern blot analysis, the expression of Msx-1, but not Msx-2, in the developing palate and in primary cultures of murine embryonic palate mesenchymal cells. Furthermore, we propose a role for Msx-1 in retinoic acid-induced cleft palate, since retinoic acid inhibits Msx-1 mRNA expression in palate mesenchymal cells. We also demonstrate that transforming growth factor beta inhibits Msx-1 mRNA expression in palate mesenchymal cells, with retinoic acid and transforming growth factor beta acting synergistically when added simultaneously to these cells. These data suggest a mechanistic interaction between retinoic acid, transforming growth factor beta, and Msx-1 in the etiology of retinoic acid-induced cleft palate.
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Affiliation(s)
- P Nugent
- Department of Biological and Biophysical Sciences, University of Louisville School of Dentistry, Kentucky 40292, USA
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