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Mariani M, Fintini D, Cirillo G, Palumbo S, Del Giudice EM, Bocchini S, Manco M, Cappa M, Grandone A. MKRN3 circulating levels in Prader-Willi syndrome: a pilot study. J Endocrinol Invest 2022; 45:2165-2170. [PMID: 35854182 DOI: 10.1007/s40618-022-01860-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 07/03/2022] [Indexed: 10/17/2022]
Abstract
CONTEXT Hypogonadism in Prader-Willi syndrome (PWS) is generally attributed to hypothalamic dysfunction or to primary gonadal defect. MKRN3, a maternal imprinted gene located on 15q11.2-q13 region, encodes makorin ring finger protein 3, whose deficiency causes precocious puberty, an extremely rare symptom in PWS. OBJECTIVE This study aimed to evaluate MKRN3 levels in patients with PWS and to analyze its correlation with sexual hormone levels, insulin resistance and Body Mass Index (BMI). METHODS We performed an observational cross-sectional study and enrolled 80 patients with genetically confirmed diagnosis of PWS with median age of 9.6 years. RESULTS MKRN3 levels were measurable in 49 PWS patients with a geometric mean of 34.9 ± 22 pg/ml (median: 28.4). Unmeasurable levels of MKRN3 were found in 31 patients. No statistically significant differences were found between patients with and without measurable MKRN3 levels for any clinical, biochemical, or genetic characteristics. However, MKRN3 levels were inversely correlated with HOMA-IR index (p: 0.005) and HbA1c (p: 0.046) values. No statistically significant correlations were found between MKRN3 and LH, estradiol and testosterone concentrations, pubertal development and genetic defect, whereas a direct correlation with FSH was found (p: 0.007). CONCLUSIONS The typical genetic defect of PWS should lead to unmeasurable levels of the MKRN3 protein due to the inactivation of the paternal allele. Measurable circulating MKRN3 could suggest the possible involvement of tissue-specific imprinting mechanisms and other regulatory factors in gene expression. Correlations with HOMA-IR index, HbA1c, and FSH suggest peripheral actions of MKRN3, but future studies are warranted to investigate this topic.
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Affiliation(s)
- M Mariani
- Endocrinology Unit, University Pediatric Department, Bambino Gesù Children's Hospital, Piazza S.Onofrio, 4, 00165, Rome, Italy.
| | - D Fintini
- Endocrinology Unit, University Pediatric Department, Bambino Gesù Children's Hospital, Piazza S.Onofrio, 4, 00165, Rome, Italy
| | - G Cirillo
- Department of Woman, Child, General and Specialized Surgery, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - S Palumbo
- Department of Woman, Child, General and Specialized Surgery, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - E M Del Giudice
- Department of Woman, Child, General and Specialized Surgery, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - S Bocchini
- Endocrinology Unit, University Pediatric Department, Bambino Gesù Children's Hospital, Piazza S.Onofrio, 4, 00165, Rome, Italy
| | - M Manco
- Research Area for Multifactorial Diseases and Complex Phenotypes, Bambino Gesù Children's Hospital, Rome, Italy
| | - M Cappa
- Endocrinology Unit, University Pediatric Department, Bambino Gesù Children's Hospital, Piazza S.Onofrio, 4, 00165, Rome, Italy
| | - A Grandone
- Department of Woman, Child, General and Specialized Surgery, University of Campania "Luigi Vanvitelli", Naples, Italy
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Palumbo S, Cirillo G, Aiello F, Papparella A, Miraglia del Giudice E, Grandone A. MKRN3 role in regulating pubertal onset: the state of art of functional studies. Front Endocrinol (Lausanne) 2022; 13:991322. [PMID: 36187104 PMCID: PMC9523110 DOI: 10.3389/fendo.2022.991322] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 08/23/2022] [Indexed: 11/25/2022] Open
Abstract
Puberty is a critical process characterized by several physical and psychological changes that culminate in the achievement of sexual maturation and fertility. The onset of puberty depends on several incompletely understood mechanisms that certainly involve gonadotropin-releasing hormone (GnRH) and its effects on the pituitary gland. The role of makorin ring finger protein 3 (MKRN3) in the regulation of pubertal timing was revealed when loss-of-function mutations were identified in patients with central precocious puberty (CPP), which to date, represent the most commonly known genetic cause of this condition. The MKRN3 gene showed ubiquitous expression in tissues from a broad spectrum of species, suggesting an important cellular role. Its involvement in the initiation of puberty and endocrine functions has just begun to be studied. This review discusses some of the recent approaches developed to predict MKRN3 functions and its involvement in pubertal development.
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Pólvora-Brandão D, Joaquim M, Godinho I, Aprile D, Álvaro AR, Onofre I, Raposo AC, Pereira de Almeida L, Duarte ST, da Rocha ST. Loss of hierarchical imprinting regulation at the Prader-Willi/Angelman syndrome locus in human iPSCs. Hum Mol Genet 2018; 27:3999-4011. [PMID: 30102380 PMCID: PMC6240739 DOI: 10.1093/hmg/ddy274] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 07/18/2018] [Accepted: 07/18/2018] [Indexed: 12/13/2022] Open
Abstract
The human chr15q11-q13 imprinted cluster is linked to several disorders, including Prader-Willi (PWS) and Angelman (AS) syndromes. Recently, disease modeling approaches based on induced pluripotent stem cells (iPSCs) have been used to study these syndromes. A concern regarding the use of these cells for imprinted disease modeling is the numerous imprinting defects found in many iPSCs. Here, by reprogramming skin fibroblasts from a control and AS individuals, we generated several iPSC lines and addressed the stability of imprinting status across the PWS/AS domain. We focused on three important regulatory DNA elements which are all differentially methylated regions (DMRs), methylated on the maternal allele: the PWS imprinting center (PWS-IC), which is a germline DMR and the somatic NDN and MKRN3 DMRs, hierarchically controlled by PWS-IC. Normal PWS-IC methylation pattern was maintained in most iPSC lines; however, loss of maternal methylation in one out of five control iPSC lines resulted in a monoallelic to biallelic switch for many imprinted genes in this domain. Surprisingly, MKRN3 DMR was found aberrantly hypermethylated in all control and AS iPSCs, regardless of the methylation status of the PWS-IC master regulator. This suggests a loss of hierarchical control of imprinting at PWS/AS region. We confirmed these results in established iPSC lines derived using different reprogramming procedures. Overall, we show that hierarchy of imprinting control in donor cells might not apply to iPSCs, accounting for their spectrum of imprinting alterations. Such differences in imprinting regulation should be taken into consideration for the use of iPSCs in disease modeling.
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Affiliation(s)
- Duarte Pólvora-Brandão
- Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal
| | - Mariana Joaquim
- Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal
| | - Inês Godinho
- Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal
| | - Domenico Aprile
- Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal
| | - Ana Rita Álvaro
- CNC - Center for Neurosciences and Cell Biology, University of Coimbra, Coimbra, Portugal
- Institute for Interdisciplinary Research (IIIUC), University of Coimbra, Coimbra, Portugal
| | - Isabel Onofre
- CNC - Center for Neurosciences and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Ana Cláudia Raposo
- Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal
| | - Luís Pereira de Almeida
- CNC - Center for Neurosciences and Cell Biology, University of Coimbra, Coimbra, Portugal
- Faculty of Pharmacy, University of Coimbra,Coimbra, Portugal
| | - Sofia T Duarte
- Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal
- Hospital D. Estefânia, Centro Hospitalar Lisboa Central, Lisboa, Portugal
| | - Simão T da Rocha
- Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal
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Khan WA, Rogan PK, Knoll JHM. Reversing chromatin accessibility differences that distinguish homologous mitotic metaphase chromosomes. Mol Cytogenet 2015; 8:65. [PMID: 26273322 PMCID: PMC4535684 DOI: 10.1186/s13039-015-0159-y] [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: 05/05/2015] [Accepted: 07/09/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Chromatin-modifying reagents that alter histone associating proteins, DNA conformation or its sequence are well established strategies for studying chromatin structure in interphase (G1, S, G2). Little is known about how these compounds act during metaphase. We assessed the effects of these reagents at genomic loci that show reproducible, non-random differences in accessibility to chromatin that distinguish homologous targets by single copy DNA probe fluorescence in situ hybridization (scFISH). By super-resolution 3-D structured illumination microscopy (3D-SIM) and other criteria, the differences correspond to 'differential accessibility' (DA) to these chromosomal regions. At these chromosomal loci, DA of the same homologous chromosome is stable and epigenetic hallmarks of less accessible interphase chromatin are present. RESULTS To understand the basis for DA, we investigate the impact of epigenetic modifiers on these allelic differences in chromatin accessibility between metaphase homologs in lymphoblastoid cell lines. Allelic differences in metaphase chromosome accessibility represent a stable chromatin mark on mitotic metaphase chromosomes. Inhibition of the topoisomerase IIα-DNA cleavage complex reversed DA. Inter-homolog probe fluorescence intensity ratios between chromosomes treated with ICRF-193 were significantly lower than untreated controls. 3D-SIM demonstrated that differences in hybridized probe volume and depth between allelic targets were equalized by this treatment. By contrast, DA was impervious to chromosome decondensation treatments targeting histone modifying enzymes, cytosine methylation, as well as in cells with regulatory defects in chromatid cohesion. These data altogether suggest that DA is a reflection of allelic differences in metaphase chromosome compaction, dictated by the localized catenation state of the chromosome, rather than by other epigenetic marks. CONCLUSIONS Inhibition of the topoisomerase IIα-DNA cleavage complex mitigated DA by decreasing DNA superhelicity and axial metaphase chromosome condensation. This has potential implications for the mechanism of preservation of cellular phenotypes that enables the same chromatin structure to be correctly reestablished in progeny cells of the same tissue or individual.
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Affiliation(s)
- Wahab A. Khan
- />Department of Pathology and Laboratory Medicine, University of Western Ontario, London, N6A 5C1 ON Canada
| | - Peter K. Rogan
- />Departments of Biochemistry, Computer Science, and Oncology, University of Western Ontario, London, N6A 5C1 ON Canada
- />Cytognomix, Inc., London, N6G 4X8 ON Canada
| | - Joan H. M. Knoll
- />Department of Pathology and Laboratory Medicine, University of Western Ontario, London, N6A 5C1 ON Canada
- />Cytognomix, Inc., London, N6G 4X8 ON Canada
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Matarazzo V, Muscatelli F. Natural breaking of the maternal silence at the mouse and human imprinted Prader-Willi locus: A whisper with functional consequences. Rare Dis 2013; 1:e27228. [PMID: 25003016 PMCID: PMC3978896 DOI: 10.4161/rdis.27228] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Revised: 11/15/2013] [Accepted: 11/15/2013] [Indexed: 12/22/2022] Open
Abstract
Genomic imprinting is a normal process of epigenetic regulation leading some autosomal genes to be expressed from one parental allele only, the other parental allele being silenced. The reasons why this mechanism has been selected throughout evolution are not clear; however, expression dosage is critical for imprinted genes. There is a paradox between the fact that genomic imprinting is a robust mechanism controlling the expression of specific genes and the fact that this mechanism is based on epigenetic regulation that, per se, should present some flexibility. The robustness has been well studied, revealing the epigenetic modifications at the imprinted locus, but the flexibility has been poorly investigated.
Prader-Willi syndrome is the best-studied disease involving imprinted genes caused by the absence of expression of paternally inherited alleles of genes located in the human 15q11-q13 region. Until now, the silencing of the maternally inherited alleles was like a dogma. Rieusset et al. showed that in absence of the paternal Ndn allele, in Ndn +m/-p mice, the maternal Ndn allele is expressed at an extremely low level with a high degree of non-genetic heterogeneity. In about 50% of these mutant mice, this stochastic expression reduces birth lethality and severity of the breathing deficiency, correlated with a reduction in the loss of serotonergic neurons. Furthermore, using several mouse models, they reveal a competition between non-imprinted Ndn promoters, which results in monoallelic (paternal or maternal) Ndn expression, suggesting that Ndn monoallelic expression occurs in the absence of imprinting regulation. Importantly, specific expression of the maternal NDN allele is also detected in post-mortem brain samples of PWS individuals. Here, similar expression of the Magel2 maternal allele is reported in Magel2 +m/-p mice, suggesting that this loss of imprinting can be extended to other PWS genes. These data reveal an unexpected epigenetic flexibility of PWS imprinted genes that could be exploited to reactivate the functional but dormant maternal alleles in PWS.
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Rieusset A, Schaller F, Unmehopa U, Matarazzo V, Watrin F, Linke M, Georges B, Bischof J, Dijkstra F, Bloemsma M, Corby S, Michel FJ, Wevrick R, Zechner U, Swaab D, Dudley K, Bezin L, Muscatelli F. Stochastic loss of silencing of the imprinted Ndn/NDN allele, in a mouse model and humans with prader-willi syndrome, has functional consequences. PLoS Genet 2013; 9:e1003752. [PMID: 24039599 PMCID: PMC3764186 DOI: 10.1371/journal.pgen.1003752] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 07/10/2013] [Indexed: 12/27/2022] Open
Abstract
Genomic imprinting is a process that causes genes to be expressed from one allele only according to parental origin, the other allele being silent. Diseases can arise when the normally active alleles are not expressed. In this context, low level of expression of the normally silent alleles has been considered as genetic noise although such expression has never been further studied. Prader-Willi Syndrome (PWS) is a neurodevelopmental disease involving imprinted genes, including NDN, which are only expressed from the paternally inherited allele, with the maternally inherited allele silent. We present the first in-depth study of the low expression of a normally silent imprinted allele, in pathological context. Using a variety of qualitative and quantitative approaches and comparing wild-type, heterozygous and homozygous mice deleted for Ndn, we show that, in absence of the paternal Ndn allele, the maternal Ndn allele is expressed at an extremely low level with a high degree of non-genetic heterogeneity. The level of this expression is sex-dependent and shows transgenerational epigenetic inheritance. In about 50% of mutant mice, this expression reduces birth lethality and severity of the breathing deficiency, correlated with a reduction in the loss of serotonergic neurons. In wild-type brains, the maternal Ndn allele is never expressed. However, using several mouse models, we reveal a competition between non-imprinted Ndn promoters which results in monoallelic (paternal or maternal) Ndn expression, suggesting that Ndn allelic exclusion occurs in the absence of imprinting regulation. Importantly, specific expression of the maternal NDN allele is also detected in post-mortem brain samples of PWS individuals. Our data reveal an unexpected epigenetic flexibility of PWS imprinted genes that could be exploited to reactivate the functional but dormant maternal alleles in PWS. Overall our results reveal high non-genetic heterogeneity between genetically identical individuals that might underlie the variability of the phenotype.
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Affiliation(s)
- Anne Rieusset
- INSERM, Institut de Neurobiologie de la Méditerranée (INMED) U901, Marseille, France
- Aix-Marseille Université, INMED UMR901, Marseille, France
| | - Fabienne Schaller
- INSERM, Institut de Neurobiologie de la Méditerranée (INMED) U901, Marseille, France
- Aix-Marseille Université, INMED UMR901, Marseille, France
| | - Unga Unmehopa
- Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Valery Matarazzo
- INSERM, Institut de Neurobiologie de la Méditerranée (INMED) U901, Marseille, France
- Aix-Marseille Université, INMED UMR901, Marseille, France
| | - Françoise Watrin
- INSERM, Institut de Neurobiologie de la Méditerranée (INMED) U901, Marseille, France
- Aix-Marseille Université, INMED UMR901, Marseille, France
| | - Matthias Linke
- Universitätsmedizin der Johannes Gutenberg-Universität Mainz Institut für Humangenetik, Mainz, Germany
| | - Beatrice Georges
- INSERM, U1028, CNRS, UMR5292, Université Claude Bernard Lyon 1, Lyon Neuroscience Center, Villeurbanne, France
| | - Jocelyn Bischof
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
| | - Femke Dijkstra
- Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Monique Bloemsma
- Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Severine Corby
- INSERM, Institut de Neurobiologie de la Méditerranée (INMED) U901, Marseille, France
- Aix-Marseille Université, INMED UMR901, Marseille, France
| | - François J. Michel
- INSERM, Institut de Neurobiologie de la Méditerranée (INMED) U901, Marseille, France
- Aix-Marseille Université, INMED UMR901, Marseille, France
| | - Rachel Wevrick
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
| | - Ulrich Zechner
- Universitätsmedizin der Johannes Gutenberg-Universität Mainz Institut für Humangenetik, Mainz, Germany
| | - Dick Swaab
- Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Keith Dudley
- INSERM, Institut de Neurobiologie de la Méditerranée (INMED) U901, Marseille, France
- Aix-Marseille Université, INMED UMR901, Marseille, France
| | - Laurent Bezin
- INSERM, U1028, CNRS, UMR5292, Université Claude Bernard Lyon 1, Lyon Neuroscience Center, Villeurbanne, France
| | - Françoise Muscatelli
- INSERM, Institut de Neurobiologie de la Méditerranée (INMED) U901, Marseille, France
- Aix-Marseille Université, INMED UMR901, Marseille, France
- * E-mail:
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Mertens D, Wolf S, Tschuch C, Mund C, Kienle D, Ohl S, Schroeter P, Lyko F, Döhner H, Stilgenbauer S, Lichter P. Allelic silencing at the tumor-suppressor locus 13q14.3 suggests an epigenetic tumor-suppressor mechanism. Proc Natl Acad Sci U S A 2006; 103:7741-6. [PMID: 16684883 PMCID: PMC1472515 DOI: 10.1073/pnas.0600494103] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Indexed: 01/23/2023] Open
Abstract
Genomic material from chromosome band 13q14.3 distal to the retinoblastoma locus is recurrently lost in a variety of human neoplasms, indicating an as-yet-unidentified tumor-suppressor mechanism. No pathogenic mutations have been found in the minimally deleted region until now. However, in B cell chronic lymphocytic leukemia tumors with loss of one copy of the critical region, respective candidate tumor-suppressor genes are down-regulated by a factor >2, which would be expected by a normal gene-dosage effect. This finding points to an epigenetic pathomechanism. We find that the two copies of the critical region replicate asynchronously, suggesting differential chromatin packaging of the two copies of 13q14.3. Although we also detect monoallelic silencing of genes localized in the critical region, monoallelic expression originates from either the maternal or paternal copy, excluding an imprinting mechanism. DNA methylation analyses revealed one CpG island of the region to be methylated. DNA demethylation of this CpG island and global histone hyperacetylation induced biallelic expression, whereas replication timing was not affected. We propose that differential replication timing represents an early epigenetic mark that distinguishes the two copies of 13q14.3, resulting in differential chromatin packaging and monoallelic expression. Accordingly, deletion of the single active copy of 13q14.3 results in significant down-regulation of the candidate genes and loss of function, providing a model for the interaction of genetic lesions and epigenetic silencing at 13q14.3 in B cell chronic lymphocytic leukemia.
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Affiliation(s)
- Daniel Mertens
- Department of Molecular Genetics, Deutsches Krebsforschungszentrum, INF 280, 69120 Heidelberg, Germany.
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Chamberlain SJ, Johnstone KA, DuBose AJ, Simon TA, Bartolomei MS, Resnick JL, Brannan CI. Evidence for genetic modifiers of postnatal lethality in PWS-IC deletion mice. Hum Mol Genet 2004; 13:2971-7. [PMID: 15459179 DOI: 10.1093/hmg/ddh314] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Prader-Willi syndrome (PWS), most notably characterized by infantile hypotonia, short stature and morbid obesity, results from deficiencies in multiple genes that are subject to genomic imprinting. The usefulness of current mouse models of PWS has been limited by postnatal lethality in affected mice. Here, we report the survival of the PWS-imprinting center (IC) deletion mice on a variety of strain backgrounds. Expression analyses of the genes affected in the PWS region suggest that while there is low-level expression from both parental alleles in PWS-IC deletion pups, this expression does not explain their survival on certain strain backgrounds. Rather, the data provide evidence for strain-specific modifier genes that support the survival of PWS-IC deletion mice.
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Affiliation(s)
- Stormy J Chamberlain
- Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, FL 32610, USA
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9
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Paulsen M, Ferguson-Smith AC. DNA methylation in genomic imprinting, development, and disease. J Pathol 2001; 195:97-110. [PMID: 11568896 DOI: 10.1002/path.890] [Citation(s) in RCA: 179] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Changes in DNA methylation profiles are common features of development and in a number of human diseases, such as cancer and imprinting disorders like Beckwith-Wiedemann and Prader-Willi/Angelman syndromes. This suggests that DNA methylation is required for proper gene regulation during development and in differentiated tissues and has clinical relevance. DNA methylation is also involved in X-chromosome inactivation and the allele-specific silencing of imprinted genes. This review describes possible mechanisms by which DNA methylation can regulate gene expression, using imprinted genes as examples. The molecular basis of methylation-mediated gene regulation is related to changes in chromatin structure and appears to be similar for both imprinted and biallelically expressed genes.
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Affiliation(s)
- M Paulsen
- University of Cambridge, Department of Anatomy, Cambridge CB2 3DY, UK
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10
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Abstract
Since the initial medical description by Prader, Labhart and Willi in 1956 of individuals with overlapping features, the Prader-Willi syndrome has become recognized as a classical but sporadic genetic syndrome. Prader-Willi syndrome is the most common genetic cause of life-threatening obesity in humans. It is estimated that there are 350,000-400,000 people with this syndrome worldwide. Prader-Willi Syndrome Association USA knows of more than 3,400 persons with Prader-Willi syndrome in the USA out of an approximate 17,000-22,000. Prader-Willi syndrome with an incidence of 1 in 10,000 to 25,000 individuals and Angelman syndrome, an entirely different clinical condition, were the first examples in humans of genetic imprinting. Genetic imprinting or the differential expression of genetic information depending on the parent of origin plays a significant role in other conditions including malignancies.
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Affiliation(s)
- Merlin G Butler
- Children's Mercy Hospitals and Clinics (M.G.B.), Kansas City, Missouri; and John F. Kennedy Center (T.T.), Vanderbilt University, Nashville, Tennessee
| | - Travis Thompson
- Children's Mercy Hospitals and Clinics (M.G.B.), Kansas City, Missouri; and John F. Kennedy Center (T.T.), Vanderbilt University, Nashville, Tennessee
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11
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Dai KS, Liew CC. Chromosomal, in silico and in vitro expression analysis of cardiovascular-based genes encoding zinc finger proteins. J Mol Cell Cardiol 1999; 31:1749-69. [PMID: 10471358 DOI: 10.1006/jmcc.1999.1011] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Three hundred and sixty expressed sequence tags (ESTs) from human heart cDNA libraries corresponding to one hundred and twenty six unique zinc finger proteins (ZFPs) were annotated and classified into seven types of ZFPs as reported previously. Among these 126 cvbZFPs (cardiovascular-based ZFPs), the C(2)H(2)-type and the C(2)C(2)-type are the two major ZFP types which account for more than 80% of ZFP genes present in the cardiovascular system. The expression patterns of 11 randomly selected ZFP genes (at least one for each type) in normal fetal, adult and hypertrophic adult hearts, respectively, were determined using reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. The results suggest that ZFPs may be involved in the processes of either developmental control (downregulated or upregulated expression) or basic cellular functional regulation (constant expression). Interestingly, PAF-1 (peroxisome assembly factor-1), a C(3)HC(4)-type ZFP (RING domain-containing ZFP) showing a downregulated expression pattern in normal tissues was found to be upregulated in hypertrophic adult heart, suggesting a possible role for this fetal gene in the pathogenesis of cardiac hypertrophy. In silico Northern analysis of 15 tissues showed that over 90% of cvbZFPs demonstrate widespread tissue distribution, suggesting the vast majority of ZFPs are functionally shared among tissues. The potential importance of transcriptional repressors in cardiovascular development and disease, such as HFHZ, was supported by the observation that one-third (39 of 126) of cvbZFPs possess this function. Of these, 26 are C(2)H(2)-type and the remaining 13 included 8 C(2)C(2)-type, 1 C(3)HC(4)-type, 1 C(2)HC(4)C(HD)-type, 2 C(3)H-type and 1 combination type. Of particular interest was the observation that ZFPs which contain a KRAB domain are the major subtype present (51. 3% of the total repressors in cvbZFPs). Chromosomal distribution analysis showed that mapping loci of cvbZFP genes are concentrated on chromosomes 1, 3, 6, 8, 10, 11, 12, 19 and X. In particular, chromosome 19 appears to be enriched in ZFP genes with C(2)H(2)-type as the predominant type present. Overall, this report provides a fundamental initial step toward understanding the potential role of ZFPs in regulating cadiac development and disease.
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Affiliation(s)
- K S Dai
- The Cardiac Gene Unit, Institute of Medical Science Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada
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Muralidhar B, Marney A, Butler MG. Analysis of imprinted genes in subjects with Prader-Willi syndrome and chromosome 15 abnormalities. Genet Med 1999; 1:141-5. [PMID: 11258349 PMCID: PMC6744832 DOI: 10.1097/00125817-199905000-00005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
PURPOSE To determine gene expression of five imprinted genes or transcripts from the 15q11-q13 chromosome region using reverse transcription polymerase chain reaction (RT-PCR) in a relatively large survey of Prader-Willi syndrome (PWS) and control subjects with several different chromosome 15 abnormalities. METHODS RT-PCR was undertaken on mRNA isolated from tissue (e.g., mostly lymphoblasts) from 38 PWS and 10 control subjects. DNA primers were used for five imprinted genes or transcripts (ZNF127, SNRPN, PAR5, IPW, and PAR1) from 15q11-q13 and fibrillin, a control gene from 15q21. RESULTS One PWS subject with maternal disomy 15 showed weak but detectable expression of PAR1, whereas SNRPN expression was detected in two PWS subjects [one with the 15q11-q13 deletion and one with a t(15;15) karyotype and maternal disomy 15], and the remaining typical PWS subjects showed no expression of the imprinted genes or transcripts. CONCLUSION No obvious clinical differences were identified in those PWS subjects with weak expression of genes compared with those showing no expression. Although the reason(s) for weak expression is unknown, possible explanations include relaxation of imprinting caused by failure to reset the imprinted genes or transcripts in the maternal germ line or by postzygotic gene expression or undetected chromosome 15 mosaicism in the deletion PWS subjects. The timing, tissue source, and other factors relating to partial expression of genes that are thought to be imprinted may play a role in clinical variability and allow for a better understanding of molecular mechanisms in PWS and other abnormalities of proximal chromosome 15q.
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Affiliation(s)
- B Muralidhar
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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