• BMB Reports
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• v.48 no.2
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• pp.61-67
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• 2015

Norovirus is a major cause of viral gastroenteritis and a common cause of foodborne and waterborne outbreaks. Norovirus outbreaks are responsible for economic losses, most notably to the public health and food industry field. Norovirus has characteristics such as low infectious dose, prolonged shedding period, strong stability, great diversity, and frequent genome mutations. Besides these characteristics, they are known for rapid and extensive spread in closed settings such as hospitals, hotels, and schools. Norovirus is well known as a major agent of food-poisoning in diverse settings in South Korea. For these reasons, nationwide surveillance for norovirus is active in both clinical and environmental settings in South Korea. Recent studies have reported the emergence of variants and novel recombinants of norovirus. In this review, we summarized studies on the molecular epidemiology and nationwide surveillance of norovirus in South Korea. This review will provide information for vaccine development and prediction of new emerging variants of norovirus in South Korea.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.168-171
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• 2000

The thermal stability and catalytic activity of phospholipase A$_1$ from Serratia sp. MK1 were improved by an evolutionary molecular engineering. Two thermostable mutants were isolated after sequential rounds of error-prone PCR to introduce random mutations and filter-based screening of the resultant mutant library, and identified as having six (mutant TA3) and seven (mutant TA13) amino acid substitutions, respectively. Different types of the substitutions were found in two mutants, resulting in the increase of nonploar residues (mutant TA3) or changes between side chains within polar or charged residues (mutant TA13). The wild-type and mutant enzymes were purified, and the effect of temperature on their stability and catalytic activity was investigated. The T$\sub$m/ values of TA3 and TA13 were increased by 7 and 11$^{\circ}C$, respectively. Thus, evolutionary molecular engineering was found to be an effective and efficient approach to increasing thermostability without compromising enzyme activity.

• Molecules and Cells
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• v.22 no.2
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• pp.228-232
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• 2006

The Drosophila protein, Rbp9, is homologous to human Hu, which is reported to be involved in small cell lung cancer. Rbp9 functions in cystocyte differentiation, and mutations in Rbp9 cause ovarian tumors. Here we show that the antimicrobial peptide, Attacin, is upregulated in Rbp9 mutants, especially in ovaries where tumors form. Upregulation seems to result from activation of the NF-${\kappa}B$ pathway since we detected nuclear localization of Relish in Rbp9 mutant ovaries but not in wild type ovaries. Inactivation of NF-${\kappa}B$ in the Rbp9 mutant allows prolonged survival of malformed egg chambers. We conclude that Drosophila initiates an anti-tumor defense response via activation of NF-${\kappa}B$.

• BMB Reports
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• v.52 no.1
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• pp.70-85
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• 2019

Reduction of insulin/insulin-like growth factor 1 (IGF1) signaling (IIS) extends the lifespan of various species. So far, several longevity mouse models have been developed containing mutations related to growth signaling deficiency by targeting growth hormone (GH), IGF1, IGF1 receptor, insulin receptor, and insulin receptor substrate. In addition, p70 ribosomal protein S6 kinase 1 (S6K1) knockout leads to lifespan extension. S6K1 encodes an important kinase in the regulation of cell growth. S6K1 is regulated by mechanistic target of rapamycin (mTOR) complex 1. The v-myc myelocytomatosis viral oncogene homolog (MYC)-deficient mice also exhibits a longevity phenotype. The gene expression profiles of these mice models have been measured to identify their longevity mechanisms. Here, we summarize our knowledge of long-lived mouse models related to growth and discuss phenotypic characteristics, including organ-specific gene expression patterns.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.4 no.2
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• pp.213-217
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• 2001

Purpose: Glycogen storage disease type Ia (GSD Ia) is an autosomal recessive disorder of glycogen metabolism caused by glucose-6-phosphatase (G6Pase) deficiency. The clinical manifestations of G6Pase deficiency include growth retardation, hepatomegaly, hypoglycemia, lactic acidemia, hyperlipidemia and hyperuricemia. Many mutations of this gene have been found worldwide in various ethnic groups, establishing the molecular basis of GSD Ia. To elucidate a spectrum of the G6Pase gene mutations in Korean, we analyzed mutations in Korean patients with GSD Ia. Methods: Both alleles of 9 unrelated GSD 1a patients were studied by PCR and direct DNA sequencing methods. In all patients, GSD 1a was diagnosed by the enzyme assay for the liver biopsy specimen. Results: In Korean, the most prevalent mutation was g727t substitution in exon 5, which has been reported to cause abnormal mRNA splicing: Sixteen out of 18 alleles were found to have this mutation. In addition, we identified one novel mutation, a c611g, converting a proline to an alanine at codon 178. Conclusion: Our findings suggest that a screening for the g727t mutation by noninvasive molecular method can detect most cases of GSD Ia in Korean patients.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7651-7656
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• 2013

Background: Breast cancer is the most common malignancy among women in both developed and developing countries. The burden is increasing in low-income and middle-income countries (LMCs) and threatens the public health of such societies. Introduction of expensive monoclonal antibodies to cancer treatment regimens poses a real challenge in the health systems of LMCs. Despite controversy of cost-effectiveness of bevacizumab in breast cancer, some studies indicate gain of patients from this drug. The present study aimed to propose a priority setting model for administration of anti-angiogenic agents in breast cancer via assessment of tumor angiogenesis by the microvessel density (MVD) method and associations with clinicopathological characteristics (including simultaneous mutations of TP53 and HER-2 genes). Materials and Methods: Age, axillary lymph nodes status, tumor size, stage and grade, estrogen and progesterone receptors status, HER-2/neu status (by immunohistochemistry and FISH test), TP53 mutation, Ki-67 (for proliferation assay) and CD34 (for angiogenesis assay) were assessed in 111 breast cancer patients. The molecular subtype of each tumor was also determined and correlations of simultaneous mutations of HER-2 and p53 genes with angiogenesis and other clinicopathological characteristics were evaluated. Results: There were significant associations between simultaneous mutations of HER-2 and p53 genes and all other parameters except tumor size. The degree of angiogenesis in the ERBB2 subtype was greater than the others. Younger patients showed a higher angiogenesis rate rather those older than 50 years. Conclusions: Our results demonstrated that patients with simultaneous mutations of HER-2 and p53 genes, those with ERBB2 molecular subtype and also younger women (often triple negative) seem more eligible for obtaining anti-angiogenic agents. These results suggest a model for priority setting of patients with breast cancer for treatment with anti-angiogenic drugs in LMCs.

• Korean Journal of Clinical Laboratory Science
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• v.47 no.3
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• pp.125-131
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• 2015

The discovery of activating mutations in EGFR in a subset of lung adenocarcinomas was a major advance in our understanding of lung adenocarcinoma biology, and has led to groundbreaking studies that have demonstrated the efficacy of tyrosine kinase inhibitor therapy. Cytologic specimen procedures have become increasingly popular for obtaining diagnostic material in lung carcinomas. However, frequently the small amount of material or sparseness of tumor cells obtained from cytologic preparations limit the number of specialized studies, such as mutation analysis, that can be performed. In this study we used microdissection to isolate small numbers of tumor cells to assess for EGFR mutations from 76 cytological smear slides of patients with lung adenocarcinomas. We compared our results with previous molecular assays that had been performed on either surgical or cytology specimens as part of the patient's initial clinical work-up. Not only were we able to detect the identical EGFR mutation through the pyrosequencing, but we were also able to consistently detect the mutation from as few as 25 microdissected tumor cells. Furthermore, isolating a purer population of tumor cells resulted in increased sensitivity of mutation detection as we were able to detect mutations from microdissection-enriched cases. Therefore, microdissection can not only significantly increase the number of lung adenocarcinoma patients that can be screened for EGFR mutations, but can also facilitate the use of cytologic samples in the newly emerging field of molecular-based personalized therapies.

• Tuberculosis and Respiratory Diseases
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• v.70 no.1
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• pp.21-27
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• 2011

Background: Although the gold standard method for research trials on epidermal growth factor receptor (EGFR) mutations has been direct sequencing, this approach has the limitations of low sensitivity and of being time-consuming. Peptide nucleic acid (PNA)-mediated polymerase chain reaction (PCR) clamping is known to be a more sensitive detection tool. The aim of this study was to compare the detection rate of $EGFR$ mutation and EGFR-tyrosine kinase inhibitor (TKI) responsiveness according to $EGFR$ mutation status using both methodologies. Methods: Clinical specimens from 112 NSCLC patients were analyzed for $EGFR$ mutations in exons 18, 19, 20, and 21. All clinical data and tumor specimens were obtained from 3 university hospitals in Korea. After genomic DNA was extracted from paraffin-embedded tissue specimens, both PNA-mediated PCR clamping and direct-sequencing were performed. The results and clinical response to $EGFR$-TKIs were compared. Results: Sequencing revealed a total of 35 (22.9%) mutations: 8 missense mutations in exon 21 and 26 deletion mutations in exon 19. PNA-mediated PCR clamping showed the presence of genomic alterations in 45 (28.3%) samples, including the 32 identified by sequencing plus 13 additional samples (6 in exon 19 and 7 in exon 21). Conclusion: PNA-mediated PCR clamping is simple and rapid, as well as a more sensitive method for screening of genomic alterations in $EGFR$ gene compared to direct sequencing. This data suggests that PNA-mediated PCR clamping should be implemented as a useful screening tool for detection of $EGFR$ mutations in clinical setting.

• Korean Journal of Clinical Laboratory Science
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• v.53 no.1
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• pp.41-48
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• 2021

Essential thrombocythemia (ET) is a clonal bone marrow stem cell disorder, primarily involving the megakaryocytic lineage. The WHO 2016 guidelines include the molecular detection of JAK2, MPL, and CALR mutations as a major diagnostic criterion for ET. This study aimed to determine the frequency of JAK2 V617F, MPL W515L, and CALR mutations in Iraqi Kurdish patients afflicted with ET, and to analyze their clinical and hematological features. A total of 73 Iraqi Kurdish patients with ET were enrolled as subjects, and analysis was achieved utilizing real-time PCR. The frequency of JAK2 V617F, CALR, and MPL W515L mutations was determined to be 50.7%, 22%, and 16.4%, respectively. No statistically significant difference was obtained when considering the age and gender among different genotypes. The JAK2 V617F mutated patients had significantly higher white blood cell counts and hemoglobin levels than the CALR-positive patients (P-value=0.000, 0.007, respectively), MPL W515L-positive patients (P-value=0.000, 0.000, respectively), and triple negative patients (P-value=0.000, 0.000, respectively). Also, the JAK2 V617F mutated patients showed higher platelet count as compared to the MPL W515L-positive patients (P-value=0.02) and triple negative patients (P-value=0.04). Furthermore, significantly lower white blood cell count and hemoglobin levels were associated with CALR positivity (P-value=0.000, 0.01, respectively), MPL W515L-positivity (P-value=0.001, 0.000, respectively), and triple negativity (P-value=0.000, 0.000, respectively), as compared to patients with combined mutations. In conclusion, apart from a relatively high frequency of MPL W515L mutation, our data is comparable to earlier reports, and highlights the importance of genotyping the JAK2 V617F, MPL W515L, and CALR mutations for accurate diagnosis of patients with ET.

• Molecules and Cells
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• v.38 no.3
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• pp.251-258
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• 2015

Germline mutations in the breast cancer type 2 susceptibility gene (BRCA2) are linked to familial breast cancer and the progressive bone marrow failure syndrome Fanconi anaemia. Established Brca2 mouse knockout models show embryonic lethality, but those with a truncating mutation at the C-terminus survive to birth and develop thymic lymphoma at an early age. To overcome early lethality and investigate the function of BRCA2, we used T cell-specific conditional Brca2 knockout mice, which were previously shown to develop thymic lymphoma at a low penetrance. In the current study we showed that the number of peripheral T cells, particularly na$\ddot{i}$ve pools, drastically declined with age. This decline was primarily ascribed to improper peripheral maintenance. Furthermore, heterozygous mice with one wild-type Brca2 allele manifested reduced T cell numbers, suggesting that Brca2 haploinsufficiency might also result in T cell loss. Our study reveals molecular events occurring in Brca2-deficient T cells and suggests that both heterozygous and homozygous Brca2 mutation may lead to dysfunction in T cell populations.