• The Korean Journal of Zoology
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• v.39 no.1
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• pp.75-88
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• 1996

OTF9-63 (OTF9) and P19S1O1A1 (P19) embryonal carcinoma (EC) cells were examined for their ability to produce the readivation of inactive X chromosomes from somatic cells. They were hybridized with various somatic cells and resulting HATr EC-somatic cell clones were analysed for their morphology, chromosomal replication pafterns and expression proffies of X-linked and distantiy located genes, Hprt and Pgk-1. The results demonstrated that 0RF9 cells could reactivate the inactive X chromosome whereas P19 cells could not. In adition, EC-somatic cell hybrids tended to reduce the number of sex chromosomes in long-term culture, resulting m 1:2 ratio of sex chromosomes to autosomes The use of EC cell hybrids provides an experimental system for studying the mechanism(s) of the X-reactivatio that is initiated and maintained from meiotic prophase of oogenesis to early embryogenesis.

• Genomics & Informatics
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• v.3 no.4
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• pp.154-158
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• 2005

Germ-line mutations of the BRCA1 gene confer an increased risk for breast and ovarian cancers. BRCA1 in female cells is directly related with the maintenance of the inactive X chromosome (Xi). The effect by the loss of the BRCA1 function on the X chromosome gene expression remains unclear in cancer cells. We attempted to investigate the expression pattern of the X-linked genes by performing BRCA1 knockdown via RNA interference in the MCF7 breast cancer cell line. The transcriptional and translational levels of BRCA1 were decreased over 95% in the MCF7 cells after BRCA1 knockdown. The expression patterns of one hundred ninety X-linked genes were profiled by the X chromosome-specific cDNA arrays. A total of seven percent of the X-linked genes (14/190) were aberrantly expressed by over 2-fold in the MCF7-BRCA1 knockdown cells, which contained two up-regulated genes (2/190, 1 %) and 12 down-regulated genes (12/190, 6.3%). It is interesting that 72% of the aberrantly expressed X-linked genes were located on the Xq (10/14,) region. Our data suggests that BRCA1 may not be important to maintain X chromosome inactivation in cancer because the BRCA1 knockdown did increase the expression of the only one percent of X-linked genes in the human breast cancer cells.

• Korean Journal of Medicinal Crop Science
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• v.14 no.2
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• pp.96-100
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• 2006

Regions of allelic loss on chromosomes in many tumors of human and some experimental animals are generally considered to harbor tumor-suppressor genes involved in tumorigenesis. Allelotype analyses have greatly improved our under-standing of the molecular mechanism of radiation lymphomagenesis. Previously, we and others found frequent loss of heterozygosity (LOH) on chromosomes 4, 11, 12, 16 and 19 in radiation-induced lymphomas from several $F_1$, hybrid mice. To examine possible contributions of individual tumor-suppressor genes to tumorigenesis in p53 heterozygous deficiency, we investigated the genome-wide distribution and status of LOH in radiation-induced lymphomas from $F_1$ mice with different p53 status. In this study, we found frequent LOH (more than 20%) on chromosomes 4 and 12 and on chromosomes 11, 12, 16 and 19 in radiation-induced lymphomas from $(STS/A{\times}MSM/Ms)F_1$ mice and $(STS/A{\times}MSM/Ms)F_1-p53^{KO/+}$ mice, respectively. Low incidences of LOH (10-20%) were also observed on chromosomes 11 in mice with wild-type p53, and chromosomes 1, 2, 9, 17 and X in p53 heterozygous-deficient mice. The frequency of LOH on chromosomes 9 and 11 increased in the $(STS/A{\times}MSM/Ms)F_1-p53^{KO/+}$ mice. Preferential losses of the STS-derived allele on chromosome 9 and wild-type p53 allele on chromosome 11 were also found in the p53 heterozygous-deficient mice. Thus, the putative tumor-suppressor gene regions responsible for lymphomagenesis might considerably differ due to the p53 status.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5391-5397
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• 2012

Background: Neuroblastoma (NB), like most human cancers, is characterized by genomic instability, manifested at the chromosomal level as allelic gain, loss or rearrangement. Genetics methods, as well as conventional and molecular cytogenetics may provide valuable clues for the identification of target loci and successful search for major genes in neuroblastoma. We aimed to investigate AURKA and MYCN gene rearrangements and the chromosomal aberrations (CAs) to determine the prognosis of neuroblastoma. Methods: We performed cytogenetic analysis by G-banding in 25 cases [11 girls (44%) and 14 boys (66%)] and in 25 controls. Fluorescence in situ hybridization (FISH) with AURKA and MYCN gene probes was also used on interphase nuclei to screen for alterations. Results: Some 18.4% of patient cells exhibited CAs., with a significant difference between patient and control groups in the frequencies (P<0.0001). Some 72% of the cells had structural aberrations, and only 28% had numerical chnages in patients. Structural aberrations consisted of deletions, translocations, breaks and fragility in various chromosomes, 84% and 52% of the patients having deletions and translocations, respectively. Among these expressed CAs, there was a higher frequency at 1q21, 1q32, 2q21, 2q31, 2p24, 4q31, 9q11, 9q22, 13q14, 14q11.2, 14q24, and 15q22 in patients. 32% of the patients had chromosome breaks, most frequently in chromosomes 1, 2, 3, 4, 5, 8, 9, 11, 12, 19 and X. The number of cells with breaks and the genomic damage frequencies were higher in patients (p<0.001). Aneuploidies in chromosomes X, 22, 3, 17 and 18 were most frequently observed. Numerical chromosome abnormalities were distinctive in 10.7% of sex chromosomes. Fragile sites were observed in 16% of our patients. Conclusion: Our data confirmed that there is a close correlation between amplification of the two genes, amplification of MYCN possibly contributing significantly to the oncogenic properties of AURKA. The high frequencies of chromosomal aberrations and amplifications of AURKA and MYCN genes indicate prognostic value in children with neuroblastomas and may point to contributing factors in their development.

• Molecules and Cells
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• v.38 no.11
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• pp.925-935
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• 2015

DNA methylation is a well-characterized epigenetic modification that plays central roles in mammalian development, genomic imprinting, X-chromosome inactivation and silencing of retrotransposon elements. Aberrant DNA methylation pattern is a characteristic feature of cancers and associated with abnormal expression of oncogenes, tumor suppressor genes or repair genes. Ten-eleven-translocation (TET) proteins are recently characterized dioxygenases that catalyze progressive oxidation of 5-methylcytosine to produce 5-hydroxymethylcytosine and further oxidized derivatives. These oxidized methylcytosines not only potentiate DNA demethylation but also behave as independent epigenetic modifications per se. The expression or activity of TET proteins and DNA hydroxymethylation are highly dysregulated in a wide range of cancers including hematologic and non-hematologic malignancies, and accumulating evidence points TET proteins as a novel tumor suppressor in cancers. Here we review DNA demethylation-dependent and -independent functions of TET proteins. We also describe diverse TET loss-of-function mutations that are recurrently found in myeloid and lymphoid malignancies and their potential roles in hematopoietic transformation. We discuss consequences of the deficiency of individual Tet genes and potential compensation between different Tet members in mice. Possible mechanisms underlying facilitated oncogenic transformation of TET-deficient hematopoietic cells are also described. Lastly, we address non-mutational mechanisms that lead to suppression or inactivation of TET proteins in cancers. Strategies to restore normal 5mC oxidation status in cancers by targeting TET proteins may provide new avenues to expedite the development of promising anti-cancer agents.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.18 no.2
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• pp.62-67
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• 2018

Hunter syndrome, also known as mucopolysaccharidosis Type II (MPS II), is one of the lysosomal storage diseases caused by a lack of the enzyme iduronate 2-sulfatase (I2S). Lack of the I2S enzyme activity leads to accumulation of the glycosaminoglycans (GAG), causing dysfunction of multiple organs and systems. MPS II is an X-linked recessive disease due to mutation of IDS gene located on long arm of the X chromosome (Xq28). To date, more than 350 mutations of IDS gene have been identified in Hunter syndrome. Phenotypes of MPS II are classified as either severe or attenuated depending on the degree of cognitive impairment. Because the phenotype of MPS II is related to the type of mutation, identifying mutations is useful in predicting prognosis. We recently had a case of MPS II diagnosed by exome sequencing in a 7 month old boy with infantile spasm uncontrolled by AED. He was diagnosed with hearing loss at 2 months of age, and he took vigabatrin and prednisolone to control infantile spasms diagnosed at 3 months of age. At 6 months of age, whole exome sequencing was performed to evaluate the infantile spasm and hearing loss in this patient, and the mutation c.851C>T (p.Pro284Leu) inherited from hemizygous mother was revealed. The results of urine Cetylpyridinium Chloride (CPC) precipitation test, which were negative until 8 months of age, were positive from 9 months of age. We report a case of MPS II diagnosed by exome sequencing and treated through enzyme replacement therapy from 9 months after birth.

• Childhood Kidney Diseases
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• v.3 no.2
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• pp.209-216
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• 1999

Purpose : Nephrogenic diabetes insipidus (NDI) is a rare X-linked disorder associated with renal tubule resistance to arginine vasopressin (AVP). The hypothesis that the defect underlying NDI might be a dysfunctional renal AVPR2 has recently been proven by the identification of mutations in the AVPR2 gene in NDT patients. To investigate the association of mutations in th AVPR2 gene with NDI, we analyzed the AVPR2 gene located on the X chromosome. Methods : We have analyzed the AVPR2 gene in a kindred with X-linked NDI. The proband and proband's mother were analyzed by polymerase chain reaction-single strand conformational polymorphism(PCR-SSCP) and DNA sequencing of the AVPR2 gene. We also have used restriction enzyme analysis of genomic PCR product to evaluate the AVPR2 gene. Results : C to T transition at codon 202, predictive of an exchange of tryptophan 202 by cysteine(R202C) in the third extracellular domain was identified. This mutation causes a loss of Hae III site within the gene. Conclusion : We found a R202C missense mutation in the AVPR2 gene causing X-linked NDI, and now direct mutational analysis is available for carrier screening and early diagnosis.

• Journal of Genetic Medicine
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• v.8 no.1
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• pp.44-52
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• 2011

Purpose: Cytogenetic analysis of spontaneous abortions (SABs) provides valuable information to establish the causes of fetal loss, information that is essential to provide accurate reproductive and genetic counseling couples. Such analysis also provides information on the frequencies and types of chromosomal abnormalities and associated risks of recurrence. However, there have only been a few reports of chromosomal abnormalities in small samples of SABs in the Korean population. Here, we report the incidence and spectrum of chromosomal abnormalities for cases of 470 SAB in Korea. Material and Methods: Between 2005 and 2010, a total of 470 products of conception (POC) resulting from SABs were submitted to our laboratory for cytogenetic analysis from various medical sites in Korea. The incidences and types of specific chromosomal abnormalities were determined. The abnormalities were distinguished by gestational age at the time of SAB and by maternal age. Results: The frequency of chromosomal abnormalities in POCs was 54.3% (255/470), including 228 (89.3%) numerical and 27 (10.7%: 3 balanced and 24 unbalanced) structural abnormalities. Among the numerical abnormalities, trisomy was predominant (67.0%), followed by monosomy X (12.5%), polyploidy (8.2%), triple X (0.8%), and autosomal monosomy (0.8%). The overall sex ratio (male: female) among the 470 POCs with normal and abnormal karyotypes were 0.58 and 0.65, respectively. Trisomies were identified for each autosome, with the exceptions of 1, 3, and 19. Among the 171 autosomal trisomies, trisomy 16 was the most common (19.9%), followed by trisomy 22 (13.5%), trisomy 21 (12.3 %), trisomy 15 (9.9%), and trisomies 18 and 13 (5.3%). The frequency of chromosomal abnormalities decreased with gestational age and increased with maternal age, but only because of increases in trisomies and complex abnormalities. Conclusions: We have presented a large collection of cytogenetic data for SABs collected during the past 6 years and provided a database for prenatal genetic counseling of parents who have experienced SABs in Korea.

• Childhood Kidney Diseases
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• v.8 no.1
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• pp.18-25
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• 2004

Purpose : Alport syndrome is clinically characterized by hereditary progressive nephritis causing ESRD with irregular thickening of the GBM and sensory neural hearing loss. The mutations of type IV collagen gene(COL4A5) located on the long arm of X chromosome is considered responsible for most of the structural abnormalities in the GBM of Alport patients. Since no definite clinical prognostic predictor has been reported in the disease yet, we designed this study to evaluate the significance of genetic polymorphism of the angiotensin converting enzyme in children with Alport syndrome as a prognostic factor for disease progression. Methods : ACE I/D genotype were examined by PCR amplification of the genomic DNA in 12 patients with Alport syndrome and 12 of their family members. Alport patients were divided into two groups; the conservative group, those who had preserved renal function for more than 10 years of age, the early CRF group, those who had progressed to CRF within 10 years of age. Results : The mean age of onset was $3.45{\pm}2.4$ years in the conservative group, $4.4{\pm}1.2$ years in the early CRF group. Sex ratios were 5:3 and 2:1 in each group. Among 12 cases of patients, 4 cases were in early CRF group and their mean duration of onset to CRF was 4.5 yews(8.9 years of age). Eight patients(67%) were in the conservative group and they had normal renal function for more than 10 years of age(mean duration of renal preservation was 10.6 years). The incidence of II type ACE gene were in 25.0%(3 cases), ID type in 41.7%(5 cases), DD type in 33.3%(4 cases). There was no significant difference between Alport patient and normal control(II type 44.3%, ID type 40.9%, DD type 14.8%). The incidence of DD type of early CRF group were higher than that of the conservative group(75% vs 12.5%)(p<0.05). There was no difference in ACE gene polymorphism between normal Alport family members and control group. Conclusion : Even though there was no significant difference of ACE polymorphism between Alport patients and the normal control group, the incidence of DD type is significantly increased in early CRF group which means DD type of ACE polymorphism has a possibility of being a predictor for early progression to CRF in Alport patients.