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The IGF-II-Insulin Receptor Isoform-A Autocrine Signal in Cancer: Actionable Perspectives. Cancers (Basel) 2020; 12:cancers12020366. [PMID: 32033443 PMCID: PMC7072655 DOI: 10.3390/cancers12020366] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 01/31/2020] [Accepted: 02/02/2020] [Indexed: 12/18/2022] Open
Abstract
Insulin receptor overexpression is a common event in human cancer. Its overexpression is associated with a relative increase in the expression of its isoform A (IRA), a shorter variant lacking 11 aa in the extracellular domain, conferring high affinity for the binding of IGF-II along with added intracellular signaling specificity for this ligand. Since IGF-II is secreted by the vast majority of malignant solid cancers, where it establishes autocrine stimuli, the co-expression of IGF-II and IRA in cancer provides specific advantages such as apoptosis escape, growth, and proliferation to those cancers bearing such a co-expression pattern. However, little is known about the exact role of this autocrine ligand–receptor system in sustaining cancer malignant features such as angiogenesis, invasion, and metastasis. The recent finding that the overexpression of angiogenic receptor kinase EphB4 along with VEGF-A is tightly dependent on the IGF-II/IRA autocrine system independently of IGFIR provided new perspectives for all malignant IGF2omas (those aggressive solid cancers secreting IGF-II). The present review provides an updated view of the IGF system in cancer, focusing on the biology of the autocrine IGF-II/IRA ligand–receptor axis and supporting its underscored role as a malignant-switch checkpoint target.
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Kondratiev NV, Alfimova MV, Golimbet VE. [A search of target regions for association studies between DNA methylation and cognitive impairment in schizophrenia]. Zh Nevrol Psikhiatr Im S S Korsakova 2018; 117:72-75. [PMID: 28884721 DOI: 10.17116/jnevro20171178172-75] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
AIM To develop a strategy for the search for candidate genes and targets for epigenetic studies of cognitive impairments in patients with schizophrenia. MATERIAL AND METHODS A search for literature on epigenetics of schizophrenia and cognitive functions was performed. Single nucleotide polymorphisms (SNPs) that can create or abolish a site for DNA methylation or transcription factor sites were determined using a custom script. RESULTS AND CONCLUSION Eight candidate genes, including BDNF, COMT, RELN, SNRPN, PSMA4, FAM63B, IL-1RAP, MAD1L1, as well as 750 targets in CpG islands in the linkage regions identified in GWAS of schizophrenia and 406 targets in SNV located within transcription factor binding sites were selected.
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Smith CEL, Alexandraki A, Cordery SF, Parmar R, Bonthron DT, Valleley EMA. A tissue-specific promoter derived from a SINE retrotransposon drives biallelic expression of PLAGL1 in human lymphocytes. PLoS One 2017; 12:e0185678. [PMID: 28957425 PMCID: PMC5619815 DOI: 10.1371/journal.pone.0185678] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 09/18/2017] [Indexed: 12/20/2022] Open
Abstract
The imprinted gene PLAGL1 is an important regulator of apoptosis and cell cycle arrest. Loss of its expression has been implicated in tumorigenesis in a range of different cancers, and overexpression during fetal development causes transient neonatal diabetes mellitus (TNDM). PLAGL1 lies within an imprinted region of chromosome 6q24, and monoallelic expression from the major, differentially methylated promoter (P1) occurs in most human tissues. However, in peripheral blood leukocytes, the active promoter (P2) is non-imprinted and drives biallelic transcription. We report here a novel PLAGL1 promoter (P5) derived from the insertion of a primate-specific, MIR3 SINE retrotransposon. P5 is highly utilized in lymphocytes, particularly in T cells, and like P2, directs biallelic transcription. Our results show that it is important to consider P5 in relation to PLAGL1 function in T cells when investigating the dysregulation of this gene.
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Affiliation(s)
- Claire E. L. Smith
- School of Medicine, University of Leeds, St. James’s University Hospital, Leeds, United Kingdom
| | - Alexia Alexandraki
- School of Medicine, University of Leeds, St. James’s University Hospital, Leeds, United Kingdom
| | - Sarah F. Cordery
- School of Medicine, University of Leeds, St. James’s University Hospital, Leeds, United Kingdom
| | - Rekha Parmar
- School of Medicine, University of Leeds, St. James’s University Hospital, Leeds, United Kingdom
| | - David T. Bonthron
- School of Medicine, University of Leeds, St. James’s University Hospital, Leeds, United Kingdom
| | - Elizabeth M. A. Valleley
- School of Medicine, University of Leeds, St. James’s University Hospital, Leeds, United Kingdom
- * E-mail:
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4
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Liu D, Wang Y, Yang XA, Liu D. De Novo Mutation of Paternal IGF2 Gene Causing Silver-Russell Syndrome in a Sporadic Patient. Front Genet 2017; 8:105. [PMID: 28848601 PMCID: PMC5550680 DOI: 10.3389/fgene.2017.00105] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Accepted: 07/27/2017] [Indexed: 01/08/2023] Open
Abstract
Silver–Russell syndrome (SRS) is a rare, but well-recognized disease characterized by growth disorder. To date, there are two reports arguing IGF2 mutation for the onset of SRS. Herein, we present another sporadic case harboring IGF2 mutation. The male proband was the first and only child of a non-consanguineous Chinese couple. He was small for gestational age, with relative macrocephaly at birth. Severe feeding difficulties, low feeding, and growth retardation were revealed during neonatal period. At 4.5 years old, obvious body asymmetry was noted. Whole exome sequencing identified a novel de novo c.101G > A (p.Gly34Asp, NM_000612) variant in IGF2 and Sanger sequencing validated the variant. Amplification refractory mutation system polymerase chain reaction demonstrated that the IGF2 variant was on the paternal allele. Alignment shows the variant is evolutionarily conserved. Structural modeling argues that the variant site might be important for the binding of IGF2 to its receptor. Our study provides further evidence that IGF2 mutation may be another mechanism of SRS, and we consider that IGF2 should be included in a disease specific gene panel in case it is designed for SRS routine diagnostics.
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Affiliation(s)
- Deguo Liu
- Department of Paediatrics, The Second Hospital of Anhui Medical UniversityHefei, China
| | - Yajian Wang
- Joy Orient Translational Medicine Research Center Co., Ltd.Beijing, China
| | - Xiu-An Yang
- Department of Paediatrics, The Second Hospital of Anhui Medical UniversityHefei, China.,Beijing Scientific Operation Biotechnology Co., Ltd.Beijing, China
| | - Deyun Liu
- Department of Paediatrics, The Second Hospital of Anhui Medical UniversityHefei, China
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5
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Tserga A, Binder AM, Michels KB. Impact of folic acid intake during pregnancy on genomic imprinting of IGF2/H19 and 1-carbon metabolism. FASEB J 2017; 31:5149-5158. [PMID: 28778973 DOI: 10.1096/fj.201601214rr] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 07/17/2017] [Indexed: 11/11/2022]
Abstract
Folic acid is an essential component of 1-carbon metabolism, which generates methyl groups for DNA methylation. Disruption of genomic imprinting leads to biallelic expression which may affect disease susceptibility possibly reflected in high levels of S-adenosyl-homocysteine (SAH) and low levels of S-adenosyl-methionine (SAM). We investigated the association between folic acid supplementation during pregnancy and loss of imprinting (LOI) of IGF2 and H19 genes in placentas and cord blood of 90 mother-child dyads in association with the methylenetetrahydrofolate reductase (MTHFR) genotype. Pyrosequencing was used to evaluate deviation from monoallelic expression among 47 placentas heterozygous for H19 and 37 placentas and cord blood tissues heterozygous for IGF2 and H19 methylation levels of 48 placentas. We detected relaxation of imprinting (ROI) and LOI of H19 in placentas not associated with differences in methylation levels of the H19ICR. Placentas retained monoallelic allele-specific gene expression of IGF2, but 32.4% of cord blood samples displayed LOI of IGF2 and 10.8% showed ROI. High SAH levels were significantly associated with low H19 methylation. An interesting positive association between SAM/SAH ratio and high H19 methylation levels was detected among infants with low B12 levels. Our data suggest profound differences in regulation of imprinting in placenta and cord blood; a lack of correlation of the methylome, transcriptome, and proteome; and a complex regulatory feedback network between free methyl groups and genomic imprinting at birth.-Tserga, A., Binder, A. M., Michels, K. B. Impact of folic acid intake during pregnancy on genomic imprinting of IGF2/H19 and 1-carbon metabolism.
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Affiliation(s)
- Aggeliki Tserga
- Institute for Prevention and Cancer Epidemiology, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Alexandra M Binder
- Obstetrics and Gynecology Epidemiology Center, Department of Obstetrics, Gynecology, and Reproductive Biology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; and.,Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA
| | - Karin B Michels
- Institute for Prevention and Cancer Epidemiology, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany; .,Obstetrics and Gynecology Epidemiology Center, Department of Obstetrics, Gynecology, and Reproductive Biology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; and.,Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA
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6
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Mutations in the histone methyltransferase gene KMT2B cause complex early-onset dystonia. Nat Genet 2016; 49:223-237. [PMID: 27992417 DOI: 10.1038/ng.3740] [Citation(s) in RCA: 155] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 11/14/2016] [Indexed: 02/08/2023]
Abstract
Histone lysine methylation, mediated by mixed-lineage leukemia (MLL) proteins, is now known to be critical in the regulation of gene expression, genomic stability, cell cycle and nuclear architecture. Despite MLL proteins being postulated as essential for normal development, little is known about the specific functions of the different MLL lysine methyltransferases. Here we report heterozygous variants in the gene KMT2B (also known as MLL4) in 27 unrelated individuals with a complex progressive childhood-onset dystonia, often associated with a typical facial appearance and characteristic brain magnetic resonance imaging findings. Over time, the majority of affected individuals developed prominent cervical, cranial and laryngeal dystonia. Marked clinical benefit, including the restoration of independent ambulation in some cases, was observed following deep brain stimulation (DBS). These findings highlight a clinically recognizable and potentially treatable form of genetic dystonia, demonstrating the crucial role of KMT2B in the physiological control of voluntary movement.
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7
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Lyssenko V, Groop L, Prasad RB. Genetics of Type 2 Diabetes: It Matters From Which Parent We Inherit the Risk. Rev Diabet Stud 2016; 12:233-42. [PMID: 27111116 DOI: 10.1900/rds.2015.12.233] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Type 2 diabetes (T2D) results from a co-occurrence of genes and environmental factors. There are more than 120 genetic loci suggested to be associated with T2D, or with glucose and insulin levels in European and multi-ethnic populations. Risk of T2D is higher in the offspring if the mother rather than the father has T2D. Genetically, this can be associated with a unique parent-of-origin (PoO) transmission of risk alleles, and it relates to genetic programming during the intrauterine period, resulting in the inability to increase insulin secretion in response to increased demands imposed by insulin resistance later in life. Such PoO transmission is seen for variants in the KLF14, KCNQ1, GRB10, TCF7L2, THADA, and PEG3 genes. Here we describe T2D susceptibility genes associated with defects in insulin secretion, and thereby risk of overt T2D. This review emphasizes the need to consider distorted parental transmission of risk alleles by exploring the genetic risk of T2D.
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Affiliation(s)
| | - Leif Groop
- Department of Clinical Sciences, Diabetes and Endocrinology, Clinical Research Centre, Lund University, Malmö, Sweden
| | - Rashmi B Prasad
- Department of Clinical Sciences, Diabetes and Endocrinology, Clinical Research Centre, Lund University, Malmö, Sweden
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8
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Liu W, Zhang H, Wang J, Yu G, Qiu W, Li Z, Chen M, Choy KW, Sun X. Prenatal diagnosis of complete maternal uniparental isodisomy of chromosome 4 in a fetus without congenital abnormality or inherited disease-associated variations. Mol Cytogenet 2015; 8:85. [PMID: 26539248 PMCID: PMC4632482 DOI: 10.1186/s13039-015-0190-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 10/28/2015] [Indexed: 11/10/2022] Open
Abstract
Background The prenatal diagnosis of subjects with complete uniparental isodisomy of chromosome 4 (iUPD4) has rarely been reported and poses a great challenge for genetic counseling. In this study, a prenatal case with a high (1 in 58) risk of Down syndrome was diagnosed with iUPD4 by combined chromosomal microarray analysis (CMA), whole exome sequencing (WES) and ultrasound morphology scan. Results By CMA, a pathogenic copy number variant was not detected; however, a complete maternal iUPD4 was identified in this fetus after analyzing the parental genotype results. To detect potentially autosomal recessive variants, WES was performed. Two missense and two frameshift variants were identified but were predicted with uncertain significance; none of the mutations were definitively associated with congenital abnormality or inherited disease. In addition, a detailed ultrasound morphology scan did not identify any structural abnormalities, facial dysmorphisms or intrauterine growth restriction. The family history was unremarkable. The couple was counseled with the prenatal diagnostic results, and they opted to give birth to the child. No phenotypic abnormalities were observed in this child after the first year of life. Conclusion This study provides further evidence that iUPD4 can result in a healthy live birth and demonstrates that the combined use of CMA, WES and ultrasound technology provides additional information for the prenatal diagnosis and clinical management of rare UPD events. Electronic supplementary material The online version of this article (doi:10.1186/s13039-015-0190-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- WeiQiang Liu
- Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, Key Laboratory for Major Obstetric Diseases of Guangdong Province, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150 P. R. China
| | - HuiMin Zhang
- Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, Key Laboratory for Major Obstetric Diseases of Guangdong Province, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150 P. R. China
| | - Jian Wang
- Department of Laboratory Medicine, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127 P. R. China
| | - GuoJiu Yu
- Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, Key Laboratory for Major Obstetric Diseases of Guangdong Province, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150 P. R. China
| | - WenJun Qiu
- Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, Key Laboratory for Major Obstetric Diseases of Guangdong Province, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150 P. R. China
| | - ZhiHua Li
- Department of Prenatal Diagnosis and Fetal Medical, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150 P. R. China
| | - Min Chen
- Department of Prenatal Diagnosis and Fetal Medical, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150 P. R. China
| | - Kwong Wai Choy
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, P. R. China
| | - XiaoFang Sun
- Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, Key Laboratory for Major Obstetric Diseases of Guangdong Province, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150 P. R. China
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9
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Codina-Solà M, Rodríguez-Santiago B, Homs A, Santoyo J, Rigau M, Aznar-Laín G, Del Campo M, Gener B, Gabau E, Botella MP, Gutiérrez-Arumí A, Antiñolo G, Pérez-Jurado LA, Cuscó I. Integrated analysis of whole-exome sequencing and transcriptome profiling in males with autism spectrum disorders. Mol Autism 2015; 6:21. [PMID: 25969726 PMCID: PMC4427998 DOI: 10.1186/s13229-015-0017-0] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 03/19/2015] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders with high heritability. Recent findings support a highly heterogeneous and complex genetic etiology including rare de novo and inherited mutations or chromosomal rearrangements as well as double or multiple hits. METHODS We performed whole-exome sequencing (WES) and blood cell transcriptome by RNAseq in a subset of male patients with idiopathic ASD (n = 36) in order to identify causative genes, transcriptomic alterations, and susceptibility variants. RESULTS We detected likely monogenic causes in seven cases: five de novo (SCN2A, MED13L, KCNV1, CUL3, and PTEN) and two inherited X-linked variants (MAOA and CDKL5). Transcriptomic analyses allowed the identification of intronic causative mutations missed by the usual filtering of WES and revealed functional consequences of some rare mutations. These included aberrant transcripts (PTEN, POLR3C), deregulated expression in 1.7% of mutated genes (that is, SEMA6B, MECP2, ANK3, CREBBP), allele-specific expression (FUS, MTOR, TAF1C), and non-sense-mediated decay (RIT1, ALG9). The analysis of rare inherited variants showed enrichment in relevant pathways such as the PI3K-Akt signaling and the axon guidance. CONCLUSIONS Integrative analysis of WES and blood RNAseq data has proven to be an efficient strategy to identify likely monogenic forms of ASD (19% in our cohort), as well as additional rare inherited mutations that can contribute to ASD risk in a multifactorial manner. Blood transcriptomic data, besides validating 88% of expressed variants, allowed the identification of missed intronic mutations and revealed functional correlations of genetic variants, including changes in splicing, expression levels, and allelic expression.
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Affiliation(s)
- Marta Codina-Solà
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, C/Doctor Aiguader 88, 422, Barcelona, 08003 Spain ; Hospital del Mar Research Institute (IMIM), C/Doctor Aiguader 88, Barcelona, 08003 Spain ; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBER-ER), C/ Monforte de Lemos 3-5, Madrid, 28029 Spain
| | | | - Aïda Homs
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, C/Doctor Aiguader 88, 422, Barcelona, 08003 Spain ; Hospital del Mar Research Institute (IMIM), C/Doctor Aiguader 88, Barcelona, 08003 Spain ; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBER-ER), C/ Monforte de Lemos 3-5, Madrid, 28029 Spain
| | - Javier Santoyo
- Medical Genome Project, Genomics and Bioinformatics Platform of Andalusia (GBPA), C/Albert Einstein, Cartuja Scientific and Technology Park, INSUR Builiding, Sevilla, 41092 Spain
| | - Maria Rigau
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, C/Doctor Aiguader 88, 422, Barcelona, 08003 Spain
| | - Gemma Aznar-Laín
- Pediatric Neurology, Hospital del Mar, Passeig Marítim 25-29, Barcelona, 08003 Spain
| | - Miguel Del Campo
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, C/Doctor Aiguader 88, 422, Barcelona, 08003 Spain ; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBER-ER), C/ Monforte de Lemos 3-5, Madrid, 28029 Spain ; Servicio de Genética, Hospital Vall d'Hebron, Passeig Vall d'Hebron, 119-129, Barcelona, 08015 Spain
| | - Blanca Gener
- Genetics Service, BioCruces Health Research Institute, Hospital Universitario Cruces, Plaza de Cruces 12, Barakaldo, Bizkaia 48093 Spain
| | - Elisabeth Gabau
- Pediatrics Service, Corporació Sanitària Parc Taulí, Parc Taulí 1, Sabadell, 08208 Spain
| | - María Pilar Botella
- Pediatric Neurology, Hospital de Txagorritxu, C/José de Atxotegui s/n, Victoria-Gasteiz, 01009 Spain
| | - Armand Gutiérrez-Arumí
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, C/Doctor Aiguader 88, 422, Barcelona, 08003 Spain ; Hospital del Mar Research Institute (IMIM), C/Doctor Aiguader 88, Barcelona, 08003 Spain ; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBER-ER), C/ Monforte de Lemos 3-5, Madrid, 28029 Spain
| | - Guillermo Antiñolo
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBER-ER), C/ Monforte de Lemos 3-5, Madrid, 28029 Spain ; Medical Genome Project, Genomics and Bioinformatics Platform of Andalusia (GBPA), C/Albert Einstein, Cartuja Scientific and Technology Park, INSUR Builiding, Sevilla, 41092 Spain ; Department of Genetics, Reproduction and Fetal Medicine, Institute of Biomedicine of Seville (IBIS), University Hospital Virgen del Rocío/CSIC/University of Seville, Avda Manuel Siurot s/n, Sevilla, 41013 Spain
| | - Luis Alberto Pérez-Jurado
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, C/Doctor Aiguader 88, 422, Barcelona, 08003 Spain ; Hospital del Mar Research Institute (IMIM), C/Doctor Aiguader 88, Barcelona, 08003 Spain ; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBER-ER), C/ Monforte de Lemos 3-5, Madrid, 28029 Spain
| | - Ivon Cuscó
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, C/Doctor Aiguader 88, 422, Barcelona, 08003 Spain ; Hospital del Mar Research Institute (IMIM), C/Doctor Aiguader 88, Barcelona, 08003 Spain ; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBER-ER), C/ Monforte de Lemos 3-5, Madrid, 28029 Spain
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Cheong CY, Chng K, Ng S, Chew SB, Chan L, Ferguson-Smith AC. Germline and somatic imprinting in the nonhuman primate highlights species differences in oocyte methylation. Genome Res 2015; 25:611-23. [PMID: 25862382 PMCID: PMC4417110 DOI: 10.1101/gr.183301.114] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 03/04/2015] [Indexed: 12/22/2022]
Abstract
Genomic imprinting is an epigenetic mechanism resulting in parental allele-specific gene expression. Defects in normal imprinting are found in cancer, assisted reproductive technologies, and several human syndromes. In mouse models, germline-derived DNA methylation is shown to regulate imprinting. Though imprinting is largely conserved between mammals, species- and tissue-specific domains of imprinted expression exist. Using the cynomolgus macaque (Macaca fascicularis) to assess primate-specific imprinting, we present a comprehensive view of tissue-specific imprinted expression and DNA methylation at established imprinted gene clusters. For example, like mouse and unlike human, macaque IGF2R is consistently imprinted, and the PLAGL1, INPP5F transcript variant 2, and PEG3 imprinting control regions are not methylated in the macaque germline but acquire this post-fertilization. Methylome data from human early embryos appear to support this finding. These suggest fundamental differences in imprinting control mechanisms between primate species and rodents at some imprinted domains, with implications for our understanding of the epigenetic programming process in humans and its influence on disease.
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Affiliation(s)
- Clara Y Cheong
- Growth, Development and Metabolism Program, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A-STAR), Singapore 117609
| | - Keefe Chng
- Growth, Development and Metabolism Program, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A-STAR), Singapore 117609
| | - Shilen Ng
- Growth, Development and Metabolism Program, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A-STAR), Singapore 117609
| | - Siew Boom Chew
- Growth, Development and Metabolism Program, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A-STAR), Singapore 117609
| | - Louiza Chan
- Growth, Development and Metabolism Program, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A-STAR), Singapore 117609
| | - Anne C Ferguson-Smith
- Growth, Development and Metabolism Program, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A-STAR), Singapore 117609; Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom
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11
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Imprinted genes in myeloid lineage commitment in normal and malignant hematopoiesis. Leukemia 2015; 29:1233-42. [PMID: 25703588 DOI: 10.1038/leu.2015.47] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Revised: 01/27/2015] [Accepted: 02/16/2015] [Indexed: 12/12/2022]
Abstract
Genomic imprinting is characterized by the parent-of-origin monoallelic expression of several diploid genes because of epigenetic regulation. Imprinted genes (IGs) are key factors in development, supporting the ability of a genotype to produce phenotypes in response to environmental stimuli. IGs are highly expressed during prenatal stages but are downregulated after birth. They also affect aspects of life other than growth such as cognition, behavior, adaption to novel environments, social dominance and memory consolidation. Deregulated genomic imprinting leads to developmental disorders and is associated with solid and blood cancer as well. Several data have been published highlighting the involvement of IGs in as early as the very small embryonic-like stem cells stage and further during myeloid lineage commitment in normal and malignant hematopoiesis. Therefore, we have assembled the current knowledge on the topic, based mainly on recent findings, trying not to focus on a particular cluster but rather to have a global view of several different IGs in hematopoiesis.
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12
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Tsui NBY, Jiang P, Wong YF, Leung TY, Chan KCA, Chiu RWK, Sun H, Lo YMD. Maternal Plasma RNA Sequencing for Genome-Wide Transcriptomic Profiling and Identification of Pregnancy-Associated Transcripts. Clin Chem 2014; 60:954-62. [DOI: 10.1373/clinchem.2014.221648] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
BACKGROUND
Analysis of circulating RNA in the plasma of pregnant women has the potential to serve as a powerful tool for noninvasive prenatal testing and research. However, detection of circulating RNA in the plasma in an unbiased and high-throughput manner has been technically challenging. Therefore, only a limited number of circulating RNA species in maternal plasma have been validated as pregnancy- and placenta-specific biomarkers.
METHODS
We explored the use of massively parallel sequencing for plasma transcriptome profiling in first-, second-, and third-trimester pregnant women. Genotyping was performed for amniotic fluid, placental tissues, and maternal blood cells, with exome-enriched sequencing.
RESULTS
In the early pregnancy group comprising 1 first- and 1 second-trimester pregnancy cases, the fetal contribution to the RNA pool in maternal plasma was 3.70%. The relative proportion of fetal contribution was increased to 11.28% in the late pregnancy group comprising 2 third-trimester pregnancy cases. The placental biallelic expression pattern of PAPPA (pregnancy-associated plasma protein A, pappalysin 1), a known pregnancy-specific gene, and the monoallelic expression pattern of H19 [H19, imprinted maternally expressed transcript (non-protein coding)], an imprinted maternally expressed gene, were also detected in the maternal plasma. Furthermore, by direct examination of the maternal plasma transcriptomic profiles before and after delivery, we identified a panel of pregnancy-associated genes.
CONCLUSIONS
Plasma RNA sequencing provides a holistic view of the maternal plasma transcriptomic repertoire. This technology is potentially valuable for using circulating plasma nucleic acids for prenatal testing and research.
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Affiliation(s)
- Nancy B Y Tsui
- Centre for Research into Circulating Fetal Nucleic Acids, Li Ka Shing Institute of Health Sciences
- Department of Chemical Pathology, and
| | - Peiyong Jiang
- Centre for Research into Circulating Fetal Nucleic Acids, Li Ka Shing Institute of Health Sciences
- Department of Chemical Pathology, and
| | - Yuen Fei Wong
- Centre for Research into Circulating Fetal Nucleic Acids, Li Ka Shing Institute of Health Sciences
- Department of Chemical Pathology, and
| | - Tak Y Leung
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - K C Allen Chan
- Centre for Research into Circulating Fetal Nucleic Acids, Li Ka Shing Institute of Health Sciences
- Department of Chemical Pathology, and
| | - Rossa W K Chiu
- Centre for Research into Circulating Fetal Nucleic Acids, Li Ka Shing Institute of Health Sciences
- Department of Chemical Pathology, and
| | - Hao Sun
- Centre for Research into Circulating Fetal Nucleic Acids, Li Ka Shing Institute of Health Sciences
- Department of Chemical Pathology, and
| | - Y M Dennis Lo
- Centre for Research into Circulating Fetal Nucleic Acids, Li Ka Shing Institute of Health Sciences
- Department of Chemical Pathology, and
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Abstract
PURPOSE OF REVIEW Genomic imprinting is an epigenetically-driven phenomenon that responds to environmental stimuli to determine the fetal growth trajectory. This review aims at describing the transgenerational meaning of genomic imprinting while supporting the study of genomic imprinting in placenta for the determination of an important biomarker of chronic and developmental disorders in children as driven by the environment. RECENT FINDINGS Recent work has shown that genomic imprinting reaches beyond the basic significance of an epigenetic mark regulating gene expression. Genomic imprinting has been theorized as the main determinant of epigenetic inheritance. Concomitantly, new studies in the field of molecular epidemiology became available that tie the fetal growth trajectory to genomic imprinting in response to environmental stimuli, making of genomic imprinting the driving force of the fetal growth. When carried out in placenta, the effector of the intrauterine environment as conveyed by the maternal exposure to the general life environment, the study of genomic imprinting may reveal critical information on alterations of the fetal growth trajectory. SUMMARY The study of genomic imprinting profiles in placentas from birth cohorts of individuals exposed to different environmental stimuli can provide a new, much needed, tool for the elaboration of effective public health intervention plans for child health.
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Rancourt RC, Harris HR, Barault L, Michels KB. The prevalence of loss of imprinting of H19 and IGF2 at birth. FASEB J 2013; 27:3335-43. [PMID: 23620526 DOI: 10.1096/fj.12-225284] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Imprinted genes are monoallelically expressed according to the parent of origin and are critical for proper placental and embryonic development. Disruption of methylation patterns at imprinted loci resulting in loss of imprinting (LOI) may lead to serious imprinting disorders (e.g., Beckwith-Wiedemann syndrome) and is described in some cancers (e.g., Wilms' tumor). As most research has focused on children with cancer or other abnormal phenotypes, the imprinting status in healthy infants at birth has not been characterized. We examined the prevalence of H19 and IGF2 LOI at birth by allele-specific expression assays analysis on 114 human individuals. Overall expression and methylation analyses were performed on a subset of samples. We found that LOI of H19 was observed for 4% of individuals in cord blood and 3.3% in placenta, and for IGF2 of 22% of individuals in the cord blood and 0% in placenta. Interestingly, LOI status did not correspond to aberrant methylation levels of the imprinted DMRs or with changes in overall gene expression for the majority of individuals. Our observations suggest that LOI is present in phenotypically healthy infants. Determining a "normal" human epigenotype range is important for discovering factors required to maintain a healthy pregnancy and embryonic development.
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Affiliation(s)
- Rebecca C Rancourt
- Obstetrics and Gynecology Epidemiology Center, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Ave., Boston, MA 02115, USA
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Barault L, Ellsworth RE, Harris HR, Valente AL, Shriver CD, Michels KB. Leukocyte DNA as surrogate for the evaluation of imprinted Loci methylation in mammary tissue DNA. PLoS One 2013; 8:e55896. [PMID: 23409079 PMCID: PMC3567003 DOI: 10.1371/journal.pone.0055896] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 01/04/2013] [Indexed: 01/01/2023] Open
Abstract
There is growing interest in identifying surrogate tissues to identify epimutations in cancer patients since primary target tissues are often difficult to obtain. Methylation patterns at imprinted loci are established during gametogenesis and post fertilization and their alterations have been associated with elevated risk of cancer. Methylation at several imprinted differentially methylated regions (GRB10 ICR, H19 ICR, KvDMR, SNRPN/SNURF ICR, IGF2 DMR0, and IGF2 DMR2) were analyzed in DNA from leukocytes and mammary tissue (normal, benign diseases, or malignant tumors) from 87 women with and without breast cancer (average age of cancer patients: 53; range: 31-77). Correlations between genomic variants and DNA methylation at the studied loci could not be assessed, making it impossible to exclude such effects. Methylation levels observed in leukocyte and mammary tissue DNA were close to the 50% expected for monoallellic methylation. While no correlation was observed between leukocyte and mammary tissue DNA methylation for most of the analyzed imprinted genes, Spearman's correlations were statistically significant for IGF2 DMR0 and IGF2 DMR2, although absolute methylation levels differed. Leukocyte DNA methylation levels of selected imprinted genes may therefore serve as surrogate markers of DNA methylation in cancer tissue.
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Affiliation(s)
- Ludovic Barault
- Obstetrics and Gynecology Epidemiology Center, Department of Obstetrics, Gynecology and Reproductive Biology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Rachel E. Ellsworth
- Clinical Breast Care Project, Henry M. Jackson Foundation for the Advancement of Military Medicine, Windber, Pennsylvania, United States of America
| | - Holly R. Harris
- Obstetrics and Gynecology Epidemiology Center, Department of Obstetrics, Gynecology and Reproductive Biology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Allyson L. Valente
- Clinical Breast Care Project, Windber Research Institute, Windber, Pennsylvania, United States of America
| | - Craig D. Shriver
- Clinical Breast Care Project, Walter Reed Army Medical Center, Washington, District of Columbia, United States of America
| | - Karin B. Michels
- Obstetrics and Gynecology Epidemiology Center, Department of Obstetrics, Gynecology and Reproductive Biology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America
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16
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Zhang S, Zhao S, Wang Z, Li C. Investigation of parent-of-origin SNPs in 5 imprinted genes for forensic purpose. FORENSIC SCIENCE INTERNATIONAL GENETICS SUPPLEMENT SERIES 2013. [DOI: 10.1016/j.fsigss.2013.10.155] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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17
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Belharazem D, Kirchner M, Geissler F, Bugert P, Spahn M, Kneitz B, Riedmiller H, Sauer C, Küffer S, Trojan L, Bolenz C, Michel MS, Marx A, Ströbel P. Relaxed imprinting of IGF2 in peripheral blood cells of patients with a history of prostate cancer. Endocr Connect 2012; 1:87-94. [PMID: 23781309 PMCID: PMC3681323 DOI: 10.1530/ec-12-0054] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 09/11/2012] [Indexed: 01/11/2023]
Abstract
BACKGROUND Insulin-like growth factor 2 (IGF2) is the predominant IGF in adults and regulates cell growth. In contrast to normal tissues, where IGF2 is imprinted and only expressed from the paternal allele, loss of imprinting (LOI) and biallelic IGF2 expression are observed in many cancers including prostate cancer (PCa). We here studied whether LOI of IGF2 in normal circulating peripheral blood lymphocytes can predict increased PCa risk. SAMPLES AND METHODS We analyzed IGF2 protein levels, IGF2 820G/A genotype and imprinting status, as well as methylation status of the IGF2 imprinting control region (ICR) in 113 blood samples of patients with a history of radical prostatectomy (RPE) for PCa by ELISA, restriction-fragment length polymorphism, and bisulfite-DNA sequencing. Results were compared to 249 male blood donors with unknown prostate specific antigen (PSA) status. RESULTS The 820G/A genotype was enriched in the RPE group and was associated with younger age at cancer diagnosis. LOI in patients was only slightly more frequent than in controls, but IGF2 levels were significantly higher and uncoupled from the imprinting status. Analysis of the IGF2/H19 ICR revealed marked hypermethylation. CONCLUSIONS The IGF 820G/A genotype is associated with PCa diagnosis at younger age. Increased IGF2 in patients with PCa appears to be the result of impaired imprinting in non-neoplastic cells rather than a paracrine tumor product. Uncoupling of IGF2 protein levels from imprinting status (not LOI alone) and hypermethylation of the ICR characterized PCa patients and could have the potential to indicate persons at risk in screening programs.
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Affiliation(s)
- Djeda Belharazem
- Institute of Pathology, University Medical Center Mannheim, University of HeidelbergTheodor-Kutzer-Ufer 1–368135, MannheimGermany
| | - Matthias Kirchner
- Institute of Pathology, University Medical Center Mannheim, University of HeidelbergTheodor-Kutzer-Ufer 1–368135, MannheimGermany
- Institute of Pathology NordhessenKasselGermany
| | - Franziska Geissler
- Institute of Pathology, University Medical Center Mannheim, University of HeidelbergTheodor-Kutzer-Ufer 1–368135, MannheimGermany
| | - Peter Bugert
- Institute of Transfusion Medicine and Immunology, University Medical Center Mannheim, University of HeidelbergMannheimGermany
| | - Martin Spahn
- Departments of Urology and Pediatric UrologyUniversity Hospital WürzburgWürzburgGermany
| | - Burkhard Kneitz
- Departments of Urology and Pediatric UrologyUniversity Hospital WürzburgWürzburgGermany
| | - Hubertus Riedmiller
- Departments of Urology and Pediatric UrologyUniversity Hospital WürzburgWürzburgGermany
| | - Christian Sauer
- Institute of Pathology, University Medical Center Mannheim, University of HeidelbergTheodor-Kutzer-Ufer 1–368135, MannheimGermany
| | - Stefan Küffer
- Institute of Pathology, University Medical Center Mannheim, University of HeidelbergTheodor-Kutzer-Ufer 1–368135, MannheimGermany
| | - Lutz Trojan
- University Medical Center MannheimMannheimGermany
| | | | | | - Alexander Marx
- Institute of Pathology, University Medical Center Mannheim, University of HeidelbergTheodor-Kutzer-Ufer 1–368135, MannheimGermany
| | - Philipp Ströbel
- Institute of Pathology, University Medical Center Mannheim, University of HeidelbergTheodor-Kutzer-Ufer 1–368135, MannheimGermany
- Institute of Pathology, University Medical Center Göttingen, University of GöttingenGöttingenGermany
- Correspondence should be addressed to P Ströbel Email
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18
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A Prevalence of Imprinted Genes within the Total Transcriptomes of Human Tissues and Cells. Mol Biol Int 2012; 2012:793506. [PMID: 22997578 PMCID: PMC3446743 DOI: 10.1155/2012/793506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 06/23/2012] [Accepted: 06/28/2012] [Indexed: 11/30/2022] Open
Abstract
Genomic imprinting is an epigenetic phenomenon that causes a differential expression of paternally and maternally inherited alleles of a subset of genes (the so-called imprinted genes). Imprinted genes are distributed throughout the genome and it is predicted that about 1% of the human genes may be imprinted. It is recognized that the allelic expression of imprinted genes varies between tissues and developmental stages. The current study represents the first attempt to estimate a prevalence of imprinted genes within the total human transcriptome. In silico analysis of the normalized expression profiles of a comprehensive panel of 173 established and candidate human imprinted genes was performed, in 492 publicly available SAGE libraries. The latter represent human cell and tissue samples in a variety of physiological and pathological conditions. Variations in the prevalence of imprinted genes within the total transcriptomes (ranging from 0.08% to 4.36%) and expression profiles of the individual imprinted genes are assessed. This paper thus provides a useful reference on the size of the imprinted transcriptome and expression of the individual imprinted genes.
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Garg P, Borel C, Sharp AJ. Detection of parent-of-origin specific expression quantitative trait loci by cis-association analysis of gene expression in trios. PLoS One 2012; 7:e41695. [PMID: 22912676 PMCID: PMC3422236 DOI: 10.1371/journal.pone.0041695] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 06/25/2012] [Indexed: 12/02/2022] Open
Abstract
Parent-of-origin (PofO) effects, such as imprinting are a phenomenon in which homologous chromosomes exhibit differential gene expression and epigenetic modifications according to their parental origin. Such non-Mendelian inheritance patterns are generally ignored by conventional association studies, as these tests consider the maternal and paternal alleles as equivalent. To identify regulatory regions that show PofO effects on gene expression (imprinted expression Quantitative Trait Loci, ieQTLs), here we have developed a novel method in which we associate SNP genotypes of defined parental origin with gene expression levels. We applied this method to study 59 HapMap phase II parent-offspring trios. By analyzing mother/father/child trios, rules of Mendelian inheritance allowed the parental origin to be defined for ∼95% of SNPs in each child. We used 680,475 informative SNPs and corresponding expression data for 92,167 probe sets from Affymetrix GeneChip Human Exon 1.0 ST arrays and performed four independent cis-association analyses with the expression level of RefSeq genes within 1 Mb using PLINK. Independent analyses of maternal and paternal genotypes identified two significant cis-ieQTLs (p<10−7) at which expression of genes SFT2D2 and SRRT associated exclusively with maternally inherited SNPs rs3753292 and rs6945374, respectively. 28 additional suggestive cis-associations with only maternal or paternal SNPs were found at a lower stringency threshold of p<10−6, including associations with two known imprinted genes PEG10 and TRAPPC9, demonstrating the efficacy of our method. Furthermore, comparison of our method that utilizes independent analyses of maternal and paternal genotypes with the Likelihood Ratio Test (LRT) showed it to be more effective for detecting imprinting effects than the LRT. Our method represents a novel approach that can identify imprinted regulatory elements that control gene expression, suggesting novel PofO effects in the human genome.
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Affiliation(s)
- Paras Garg
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Christelle Borel
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Andrew J. Sharp
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, New York, United States of America
- * E-mail:
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Walker EJ, Zhang C, Castelo-Branco P, Hawkins C, Wilson W, Zhukova N, Alon N, Novokmet A, Baskin B, Ray P, Knobbe C, Dirks P, Taylor MD, Croul S, Malkin D, Tabori U. Monoallelic expression determines oncogenic progression and outcome in benign and malignant brain tumors. Cancer Res 2011; 72:636-44. [PMID: 22144470 DOI: 10.1158/0008-5472.can-11-2266] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Although monoallelic expression (MAE) is a frequent genomic event in normal tissues, its role in tumorigenesis remains unclear. Here we carried out single-nucleotide polymorphism arrays on DNA and RNA from a large cohort of pediatric and adult brain tumor tissues to determine the genome-wide rate of MAE, its role in specific cancer-related genes, and the clinical consequences of MAE in brain tumors. We also used targeted genotyping to examine the role of tumor-related genes in brain tumor development and specifically examined the clinical consequences of MAE at TP53 and IDH1. The genome-wide rate of tumor MAE was higher than in previously described normal tissue and increased with specific tumor grade. Oncogenes, but not tumor suppressors, exhibited significantly higher MAE in high-grade compared with low-grade tumors. This method identified nine novel genes highly associated with MAE. Within cancer-related genes, MAE was gene specific; hTERT was most significantly affected, with a higher frequency of MAE in adult and advanced tumors. Clinically, MAE at TP53 exists only in mutated tumors and increases with tumor aggressiveness. MAE toward the normal allele at IDH1 conferred worse survival even in IDH1 mutated tumors. Taken together, our findings suggest that MAE is tumor and gene specific, frequent in brain tumor subtypes, and may be associated with tumor progression/aggressiveness. Further exploration of MAE at relevant genes may contribute to better understanding of tumor development and determine survival in brain tumor patients.
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Affiliation(s)
- Erin J Walker
- Division of Haematology/Oncology, The Labatt Brain Tumor Research Centre, The Hospital for Sick Children, Toronto General Hospital, Toronto, Ontario, Canada
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21
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Demars J, Rossignol S, Netchine I, Lee KS, Shmela M, Faivre L, Weill J, Odent S, Azzi S, Callier P, Lucas J, Dubourg C, Andrieux J, Le Bouc Y, El-Osta A, Gicquel C. New insights into the pathogenesis of Beckwith-Wiedemann and Silver-Russell syndromes: contribution of small copy number variations to 11p15 imprinting defects. Hum Mutat 2011; 32:1171-82. [PMID: 21780245 DOI: 10.1002/humu.21558] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 06/12/2011] [Indexed: 01/28/2023]
Abstract
The imprinted 11p15 region is organized in two domains, each of them under the control of its own imprinting control region (ICR1 for the IGF2/H19 domain and ICR2 for the KCNQ1OT1/CDKN1C domain). Disruption of 11p15 imprinting results in two fetal growth disorders with opposite phenotypes: the Beckwith-Wiedemann (BWS) and the Silver-Russell (SRS) syndromes. Various 11p15 genetic and epigenetic defects have been demonstrated in BWS and SRS. Among them, isolated DNA methylation defects account for approximately 60% of patients. To investigate whether cryptic copy number variations (CNVs) involving only part of one of the two imprinted domains account for 11p15 isolated DNA methylation defects, we designed a single nucleotide polymorphism array covering the whole 11p15 imprinted region and genotyped 185 SRS or BWS cases with loss or gain of DNA methylation at either ICR1 or ICR2. We describe herein novel small gain and loss CNVs in six BWS or SRS patients, including maternally inherited cis-duplications involving only part of one of the two imprinted domains. We also show that ICR2 deletions do not account for BWS with ICR2 loss of methylation and that uniparental isodisomy involving only one of the two imprinted domains is not a mechanism for SRS or BWS.
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Affiliation(s)
- Julie Demars
- Epigenetics in Human Health and Disease, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
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22
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Yuen RK, Jiang R, Peñaherrera MS, McFadden DE, Robinson WP. Genome-wide mapping of imprinted differentially methylated regions by DNA methylation profiling of human placentas from triploidies. Epigenetics Chromatin 2011; 4:10. [PMID: 21749726 PMCID: PMC3154142 DOI: 10.1186/1756-8935-4-10] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 07/13/2011] [Indexed: 12/01/2022] Open
Abstract
Background Genomic imprinting is an important epigenetic process involved in regulating placental and foetal growth. Imprinted genes are typically associated with differentially methylated regions (DMRs) whereby one of the two alleles is DNA methylated depending on the parent of origin. Identifying imprinted DMRs in humans is complicated by species- and tissue-specific differences in imprinting status and the presence of multiple regulatory regions associated with a particular gene, only some of which may be imprinted. In this study, we have taken advantage of the unbalanced parental genomic constitutions in triploidies to further characterize human DMRs associated with known imprinted genes and identify novel imprinted DMRs. Results By comparing the promoter methylation status of over 14,000 genes in human placentas from ten diandries (extra paternal haploid set) and ten digynies (extra maternal haploid set) and using 6 complete hydatidiform moles (paternal origin) and ten chromosomally normal placentas for comparison, we identified 62 genes with apparently imprinted DMRs (false discovery rate <0.1%). Of these 62 genes, 11 have been reported previously as DMRs that act as imprinting control regions, and the observed parental methylation patterns were concordant with those previously reported. We demonstrated that novel imprinted genes, such as FAM50B, as well as novel imprinted DMRs associated with known imprinted genes (for example, CDKN1C and RASGRF1) can be identified by using this approach. Furthermore, we have demonstrated how comparison of DNA methylation for known imprinted genes (for example, GNAS and CDKN1C) between placentas of different gestations and other somatic tissues (brain, kidney, muscle and blood) provides a detailed analysis of specific CpG sites associated with tissue-specific imprinting and gestational age-specific methylation. Conclusions DNA methylation profiling of triploidies in different tissues and developmental ages can be a powerful and effective way to map and characterize imprinted regions in the genome.
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Affiliation(s)
- Ryan Kc Yuen
- Department of Medical Genetics, University of British Columbia, 2329 West Mall, Vancouver, BC, V6T 1Z4, Canada.
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23
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Abstract
Detailed comprehensive molecular analysis using families and multiple matched tissues is essential to determine whether imprinted genes have a functional role in humans.
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Affiliation(s)
- Gudrun E Moore
- Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK.
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Morcos L, Ge B, Koka V, Lam KCL, Pokholok DK, Gunderson KL, Montpetit A, Verlaan DJ, Pastinen T. Genome-wide assessment of imprinted expression in human cells. Genome Biol 2011; 12:R25. [PMID: 21418647 PMCID: PMC3129675 DOI: 10.1186/gb-2011-12-3-r25] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 01/21/2011] [Accepted: 03/21/2011] [Indexed: 01/19/2023] Open
Abstract
Background Parent-of-origin-dependent expression of alleles, imprinting, has been suggested to impact a substantial proportion of mammalian genes. Its discovery requires allele-specific detection of expressed transcripts, but in some cases detected allelic expression bias has been interpreted as imprinting without demonstrating compatible transmission patterns and excluding heritable variation. Therefore, we utilized a genome-wide tool exploiting high density genotyping arrays in parallel measurements of genotypes in RNA and DNA to determine allelic expression across the transcriptome in lymphoblastoid cell lines (LCLs) and skin fibroblasts derived from families. Results We were able to validate 43% of imprinted genes with previous demonstration of compatible transmission patterns in LCLs and fibroblasts. In contrast, we only validated 8% of genes suggested to be imprinted in the literature, but without clear evidence of parent-of-origin-determined expression. We also detected five novel imprinted genes and delineated regions of imprinted expression surrounding annotated imprinted genes. More subtle parent-of-origin-dependent expression, or partial imprinting, could be verified in four genes. Despite higher prevalence of monoallelic expression, immortalized LCLs showed consistent imprinting in fewer loci than primary cells. Random monoallelic expression has previously been observed in LCLs and we show that random monoallelic expression in LCLs can be partly explained by aberrant methylation in the genome. Conclusions Our results indicate that widespread parent-of-origin-dependent expression observed recently in rodents is unlikely to be captured by assessment of human cells derived from adult tissues where genome-wide assessment of both primary and immortalized cells yields few new imprinted loci.
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Affiliation(s)
- Lisanne Morcos
- McGill University and Genome Quebec Innovation Centre, 740 Dr Penfield Avenue, Montreal, Quebec, H3A 1A4, Canada
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