Ts65Dn, a Mouse Model of Down Syndrome, Exhibits Increased GABAB-Induced Potassium Current

2007 ◽  
Vol 97 (1) ◽  
pp. 892-900 ◽  
Author(s):  
Tyler K. Best ◽  
Richard J. Siarey ◽  
Zygmunt Galdzicki
Keyword(s):  
Down Syndrome ◽  
Mouse Model ◽  
Hippocampal Neurons ◽  
Single Channel ◽  
Extra Chromosome ◽  
Functional Expression ◽  
Chromosome 21 ◽  
Fluctuation Analysis ◽  
Response Curves ◽  
Girk Channel

Down syndrome (DS) is the most common nonheritable cause of mental retardation. DS is the result of the presence of an extra chromosome 21 and its phenotype may be a consequence of overexpressed genes from that chromosome. One such gene is Kcnj6/Girk2, which encodes the G-protein-coupled inward rectifying potassium channel subunit 2 (GIRK2). We have recently shown that the DS mouse model, Ts65Dn, overexpresses GIRK2 throughout the brain and in particular the hippocampus. Here we report that this overexpression leads to a significant increase (∼2-fold) in GABAB-mediated GIRK current in primary cultured hippocampal neurons. The dose response curves for peak and steady-state GIRK current density is significantly shifted left toward lower concentrations of baclofen in Ts65Dn neurons compared with diploid controls, consistent with increased functional expression of GIRK channels. Stationary fluctuation analysis of baclofen-induced GIRK current from Ts65Dn neurons indicated no significant change in single-channel conductance compared with diploid. However, significant increases in GIRK channel density was found in Ts65Dn neurons. In normalized baclofen-induced GIRK current and GIRK current kinetics no difference was found between diploid and Ts65Dn neurons, which suggests unimpaired mechanisms of interaction between GIRK channel and GABAB receptor. These results indicate that increased expression of GIRK2 containing channels have functional consequences that likely affect the balance between excitatory and inhibitory neuronal transmission.

scholarly journals Neurodevelopmental wiring deficits in the Ts65Dn mouse model of Down syndrome

2019 ◽  
Author(s):  
Shruti Jain ◽  
Christina A. Watts ◽  
Wilson C.J. Chung ◽  
Kristy Welshhans
Keyword(s):  
Down Syndrome ◽  
Corpus Callosum ◽  
Mouse Model ◽  
Hippocampal Neurons ◽  
Anterior Commissure ◽  
Axon Growth ◽  
Chromosome 21 ◽  
Ts65dn Mouse ◽  
Hippocampal Commissure ◽  
Interhemispheric Connectivity

AbstractDown syndrome is the most common genetic cause of intellectual disability and occurs due to the trisomy of human chromosome 21. Adolescent and adult brains from humans with Down syndrome exhibit various neurological phenotypes including a reduction in the size of the corpus callosum, hippocampal commissure and anterior commissure. However, it is unclear when and how these interhemispheric connectivity defects arise. Using the Ts65Dn mouse model of Down syndrome, we examined interhemispheric connectivity in postnatal day 0 (P0) Ts65Dn mouse brains. We find that there is no change in the volume of the corpus callosum or anterior commissure in P0 Ts65Dn mice. However, the volume of the hippocampal commissure is significantly reduced in P0 Ts65Dn mice, and this may contribute to the impaired learning and memory phenotype of this disorder. Interhemispheric connectivity defects that arise during development may be due to disrupted axon growth. In line with this, we find that developing hippocampal neurons display reduced axon length in vitro, as compared to neurons from their euploid littermates. This study is the first to report the presence of defective interhemispheric connectivity at the time of birth in Ts65Dn mice, providing evidence that early therapeutic intervention may be an effective time window for the treatment of Down syndrome.

scholarly journals Ten Reasons Why People With Down Syndrome are Protected From the Development of Most Solid Tumors -A Review

2021 ◽  
Vol 12 ◽  
Author(s):  
Marta Pilar Osuna-Marco ◽  
Mónica López-Barahona ◽  
Blanca López-Ibor ◽  
Águeda Mercedes Tejera
Keyword(s):  
Down Syndrome ◽  
Solid Tumors ◽  
Tumor Suppressor Genes ◽  
Wilms Tumor ◽  
Extra Chromosome ◽  
Germ Cell Tumors ◽  
Chromosome 21 ◽  
Testicular Tumors ◽  
Unique Pattern ◽  
Increased Risk

People with Down syndrome have unique characteristics as a result of the presence of an extra chromosome 21. Regarding cancer, they present a unique pattern of tumors, which has not been fully explained to date. Globally, people with Down syndrome have a similar lifetime risk of developing cancer compared to the general population. However, they have a very increased risk of developing certain tumors (e.g., acute leukemia, germ cell tumors, testicular tumors and retinoblastoma) and, on the contrary, there are some other tumors which appear only exceptionally in this syndrome (e.g., breast cancer, prostate cancer, medulloblastoma, neuroblastoma and Wilms tumor). Various hypotheses have been developed to explain this situation. The genetic imbalance secondary to the presence of an extra chromosome 21 has molecular consequences at several levels, not only in chromosome 21 but also throughout the genome. In this review, we discuss the different proposed mechanisms that protect individuals with trisomy 21 from developing solid tumors: genetic dosage effect, tumor suppressor genes overexpression, disturbed metabolism, impaired neurogenesis and angiogenesis, increased apoptosis, immune system dysregulation, epigenetic aberrations and the effect of different microRNAs, among others. More research into the molecular pathways involved in this unique pattern of malignancies is still needed.

scholarly journals Gambaran Erupsi Gigi Permanen pada Anak Sindrom Down Usia 10-16 Tahun di Sekolah Luar Biasa Kabupaten Jember

2018 ◽  
Vol 8 (1) ◽  
pp. 8
Author(s):  
Loly Anastasya Sinaga ◽  
Dwi Kartika Apriyono ◽  
Masniari Novita
Keyword(s):  
Down Syndrome ◽  
Special Needs ◽  
Physical Characteristic ◽  
Trisomy 21 ◽  
Genetic Disorder ◽  
Extra Chromosome ◽  
Descriptive Study ◽  
Chromosome 21 ◽  
Permanent Teeth ◽  
Intellectual Abilities

Background: Down Syndrome is a genetic disorder that occurs because of chromosome 21 has three chromosome (trisomy 21). The extra chromosome changes the genetic balance, physical characteristic, intellectual abilities, and physiological body function. Tooth eruption in Down Syndrome children typically delayed in both the timing and sequence of eruption up to two or three years. Objective: To observe the permanent teeth eruption in Down syndrome children at age 10-16 years old, boys and girls in Special Needs School in Jember. Materials and Methods: This research was a descriptive study with 7 subjects. Each subject was examined then calculated teeth that had emerged or functionally eruption with articualting paper. Result and Conclusion:  Both permanent teeth that is still partially erupted tooth (emerged/ EM) and had erupted perfectly (functionally eruption/ FE) delayed in eruption in Down Syndrome boys and girls at age 10-16 years old.

A Myeloproliferative Disorder in the Tc1 Mouse Model of Down Syndrome

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2790-2790
Author(s):  
Kate A. Alford ◽  
Lesley Vanes ◽  
Zhe Li ◽  
Stuart H. Orkin ◽  
Elizabeth M. C. Fisher ◽  
...  
Keyword(s):  
Down Syndrome ◽  
Mouse Model ◽  
Extramedullary Hematopoiesis ◽  
Myeloproliferative Disorder ◽  
Chromosome 21 ◽  
Gene Encoding ◽  
Megakaryoblastic Leukemia ◽  
Cell Counts ◽  
Hematopoietic Disorders

Abstract Down syndrome (DS) children have a one in ten chance of being diagnosed with leukemia within the first ten years of life. Acute megakaryoblastic leukemia (AMKL) is a subtype of acute myeloid leukemia (AML) that accounts for nearly 50% of these leukemias. AMKL is associated with a self-regressing neoplasia found almost exclusively in DS newborns called Transient Myeloproliferative Disorder (TMD). In all cases of TMD and DS-AMKL, leukemic blast cells show mutations in the gene encoding the hematopoietic transcription factor GATA1, resulting in production of a truncated form of the protein called GATA1s. Mutations in GATA1 are not seen in non-DS-AMKL or other DS leukemias and it is clear both trisomy of human chromosome 21 (HSA21) and a mutation in GATA1 are required for the development of both TMD and AMKL. However, it is unknown which genes on HSA21 need to be trisomic in order to predispose an individual with DS to AMKL. Our group has generated mice (termed the Tc1 mice) that contain an almost complete, freely segregating copy of HSA21. These mice display phenotypic features of DS. We have examined adult hematopoiesis in these mice. Blood samples taken from a cohort of Tc1 mice were examined from 4 weeks until 60 weeks of age. Complete blood cell counts show that whilst the mice do not develop leukemia they displayed persistent macrocytosis and had reduced erythrocyte numbers. Crossing the Tc1 mice with mice that express GATA1s protein did not perturb or exacerbate this phenotype. Over the age of 15 months more than 50% of Tc1 mice examined were found to have developed splenomegaly. These mice displayed megakaryocyte hyperplasia and had increased numbers of cells of the erythroid lineage. In vitro colony forming assays demonstrated an increase in the frequency of megakaryocytic and granulocyte-macrophage progenitors in the spleen, consistent with extramedullary hematopoiesis. In the bone marrow, no abnormalities were seen in the lineage-, c-Kit+, Sca1+ (LSK) compartment, however there was a significant increase in the percentage of common myeloid progenitors (CMP) and a corresponding decrease in megakaryocyte-erythrocyte progenitors (MEP). This suggests a possible block in development from CMP to MEP. These data demonstrate defects in hematopoietic development in a proportion of adult Tc1 mice. However, preliminary data suggest that these mice do not develop a neonatal myeloproliferative disorder that is comparable with human TMD. It may be that the phenotype seen in the adult Tc1 mice is due to defects in hematopoietic progenitors that are different to those responsible for development of TMD and DS-AMKL. This mouse model may therefore provide a useful tool to examine the role of HSA21 genes in adult hematopoietic disorders.

Imbalances of Chromosome 21 in MDS/AML Include Cryptic Deletions but NOT RUNX1 Amplifications.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2561-2561
Author(s):  
Katya Gancheva ◽  
Diana Brazma ◽  
Nahid Zarein ◽  
Julie Howard-Reeves ◽  
Phaidra Partheniou ◽  
...  
Keyword(s):  
Down Syndrome ◽  
De Novo ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Extra Chromosome ◽  
Chromosome 21 ◽  
Oligonucleotide Array ◽  
Fish Analysis ◽  
Extra Copy ◽  
Commercial Fish

Abstract Abstract 2561 We present the results of a study demonstrating that the genome profile of RUNX1 in MDS/AML is characterised by hitherto unreported partial deletions and absence of amplifications. This is in stark contrast to reports of chromosome 21 amplifications in ALL. We speculate that the absence of RUNX1 deletions results from them being well below a size detectable by commercial FISH probes. Extra chromosome 21 is the second most common acquired trisomy after (+) 8 in adult myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). It is rarely observed as sole abnormality but seen as part of complex karyotype in some 3–7% of the AML (Atlas of Genetics and Cytogenetics in Oncology and Haematology, http://atlasgeneticsoncology.org). Although the gene(s) in trisomy 21 associated with leukemia are unknown, the 21q22 region appears to be critical since it houses the RUNX1 gene. Multiple amplified copies of the RUNX1 carried by marker chromosomes, such as iAML21, are described in both acute lymphoblastic leukemia (ALL) and AML. A common 5.1 Mb amplification containing the RUNX1, miR-802 and genes mapping to the Down syndrome critical region identified in 91 children with iAML21, was shown to be the likely initiating event in this rare form of childhood B-cell ALL (Rand et al., Blood, 2011). In contrast, recent studies of AML in a Down syndrome and a constitutionally normal individual showed lack of RUNX1, ETS2 and ERG involvement (Canzonetta et al., BJH, 2012). Here we present 16 MDS/AML cases with imbalances of chromosome 21 identified by genomic array screening from a cohort of 83 cases. Whole genome screening (aCGH) was performed on presentation samples of MDS /AML and de novo AML cases using an oligonucleotide array platform (Agilent) at 60K, 244K, 400K and 1M density. G banding and FISH analysis were also successfully performed. Gain of an extra copy (trisomy) of chromosome 21 (+21) was found in 9 patients, all but one with complex karyotypes. In 2 AMLs high level amplifications were detected at 21q22, which involved the ETS2 and ERG but not the RUNX1 sequences. While several commercially available RUNX1 FISH probes showed gene multiple signals, custom FISH probes covering the relevant regions confirmed that the amplifications excluded the RUNX1 but affected both EST2 and ERG thus rendering the commercial probes unfit to assess CNA in this genome area. In another two cases with trisomy 12, cryptic loss of 43Kb and 98Kb resp. within the RUNX1 sequences was detected and confirmed by FISH. Furthermore, similar deletions within the 21q22.12 were also found in another 7 cases all of which had diploid set of chromosome 21 but had multiple changes at G banding level and high TGA score. These RUNX1 deletions were variable in size, ranging from 98Kb to 2.7Mb. Although our observations excluded clinical correlations it is note worthy that most of the patients with RUNX1 loss have not achieved complete cytogenetic remission. These findings suggest role for the RUNX1 loss as indicator of progressive disease and provide a novel insight into pathogenesis of MDS/AML. Disclosures: No relevant conflicts of interest to declare.

The origin of the extra chromosome 21 in Down syndrome

1978 ◽  
Vol 20 (1-6) ◽  
pp. 194-203 ◽  
Author(s):  
A. Hansson ◽  
M. Mikkelsen
Keyword(s):  
Down Syndrome ◽  
Extra Chromosome ◽  
Chromosome 21

scholarly journals Potassium channel regulators are differentially expressed in hippocampi of Ts65Dn and Tc1 Down syndrome mouse models

2018 ◽  
Author(s):  
Shani Stern ◽  
Rinat Keren ◽  
Yongsung Kim ◽  
Elisha Moses
Keyword(s):  
Down Syndrome ◽  
Mouse Model ◽  
Potassium Channel ◽  
Mouse Models ◽  
Chromosome 21 ◽  
Neuronal Cultures ◽  
Rna Expression ◽  
Genetic Changes ◽  
Expression Levels ◽  
Whole Cell Patch Clamp

AbstractBackground:Down syndrome remains the main genetic cause of intellectual disability, with an incidence rate of about 1 in 700 live births. The Ts65Dn mouse strain, with an extra murine chromosome that includes genes from chromosomes 10, 16 and 17 of the mouse and the Tc1 strain with an extra human chromosome 21, are currently accepted as informative and well-studied models for Down Syndrome. Using whole cell patch clamp we recently showed changes in several types of transmembrane currents in hippocampal neuronal cultures of Ts65Dn and Tc1 embryos. The associated genetic changes responsible for these changes in physiology were yet to be studied.Methods:We used qPCR to measure RNA expression level of a few of the channel genes that we suspect are implicated in the previously reported changes of measured currents, and performed statistical analysis using Matlab procedures for the standard t-test and ANOVA and for calculating correlations between the RNA expression levels of several channel genes.Results:We present differential gene expression levels measured using qPCR of the potassium channel regulators KCNE1 and KCNE2 in both Ts65Dn and Tc1 embryos and pups compared to controls. In Tc1, the human genes KCNJ6 and KCNJ15 are expressed in addition to a statistically insignificant increase of expression in the mouse genes KCNJ6 and KCNJ15. All channel genes that we have measured with large replication, have the same up-regulation or down-regulation in both mouse models, indicating that the transcription mechanism acts similarly in these two mouse models. The large dataset furthermore allows us to observe correlations between different channel genes. We find that, despite the significant changes in expression levels, channels that are known to interact have a high and significant correlation in expression both in controls and in the Down syndrome mouse model.Conclusions:We suggest the differential expression of KCNE1 and KCNE2 as a possible cause for our previously reported changes in potassium currents. We report a KCNJ6 and KCNJ15 overexpression, which plays a role in the increased input conductance and the reduced cell excitability that we previously reported in the Tc1 mouse model. The large and significant positive (KCNQ2-KCNQ3, KCNE1-KCNE2, KCNQ3-KCNE1, KCNQ2-KCNE1, KCNQ2-KCNE2, KCNQ3-KCNE2) and negative correlations (KCNE1-KCNJ15, KCNE2-KCNJ15) that we find between channel genes indicate that these genes probably work in a cooperative or in a mutually exclusive manner.

scholarly journals Nuclear Reorganization in Hippocampal Granule Cell Neurons from a Mouse Model of Down Syndrome: Changes in Chromatin Configuration, Nucleoli and Cajal Bodies

2021 ◽  
Vol 22 (3) ◽  
pp. 1259
Author(s):  
Alba Puente-Bedia ◽  
María T. Berciano ◽  
Olga Tapia ◽  
Carmen Martínez-Cué ◽  
Miguel Lafarga ◽  
...  
Keyword(s):  
Down Syndrome ◽  
Mouse Model ◽  
Nuclear Architecture ◽  
Molecular Assembly ◽  
Chromosome 21 ◽  
Cajal Bodies ◽  
Nuclear Compartments ◽  
Nuclear Reorganization ◽  
Dependent Learning ◽  
Nuclear Alterations

Down syndrome (DS) or trisomy of chromosome 21 (Hsa21) is characterized by impaired hippocampal-dependent learning and memory. These alterations are due to defective neurogenesis and to neuromorphological and functional anomalies of numerous neuronal populations, including hippocampal granular cells (GCs). It has been proposed that the additional gene dose in trisomic cells induces modifications in nuclear compartments and on the chromatin landscape, which could contribute to some DS phenotypes. The Ts65Dn (TS) mouse model of DS carries a triplication of 92 genes orthologous to those found in Hsa21, and shares many phenotypes with DS individuals, including cognitive and neuromorphological alterations. Considering its essential role in hippocampal memory formation, we investigated whether the triplication of this set of Hsa21 orthologous genes in TS mice modifies the nuclear architecture of their GCs. Our results show that the TS mouse presents alterations in the nuclear architecture of its GCs, affecting nuclear compartments involved in transcription and pre-rRNA and pre-mRNA processing. In particular, the GCs of the TS mouse show alterations in the nucleolar fusion pattern and the molecular assembly of Cajal bodies (CBs). Furthermore, hippocampal GCs of TS mice present an epigenetic dysregulation of chromatin that results in an increased heterochromatinization and reduced global transcriptional activity. These nuclear alterations could play an important role in the neuromorphological and/or functional alterations of the hippocampal GCs implicated in the cognitive dysfunction characteristic of TS mice.

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