[show abstract][hide abstract] ABSTRACT: BACKGROUND: Hereditary hearing loss is one of the most common heterogeneous disorders, and genetic variants that can cause hearing loss have been identified in over fifty genes. Most of these hearing loss genes have been detected using classical genetic methods, typically starting with linkage analysis in large families with hereditary hearing loss. However, these classical strategies are not well suited for mutation analysis in smaller families who have insufficient genetic information. METHODS: Eighty known hearing loss genes were selected and simultaneously sequenced by targeted next-generation sequencing (NGS) in 8 Korean families with autosomal dominant non-syndromic sensorineural hearing loss. RESULTS: Five mutations in known hearing loss genes, including 1 nonsense and 4 missense mutations, were identified in 5 different genes (ACTG1, MYO1F, DIAPH1, POU4F3 and EYA4), and the genotypes for these mutations were consistent with the autosomal dominant inheritance pattern of hearing loss in each family. No mutational hot-spots were revealed in these Korean families. CONCLUSION: Targeted NGS allowed for the detection of pathogenic mutations in affected individuals who were not candidates for classical genetic studies. This report is the first documenting the effective use of an NGS technique to detect pathogenic mutations that underlie hearing loss in an East Asian population. Using this NGS technique to establish a database of common mutations in Korean patients with hearing loss and further data accumulation will contribute to the early diagnosis and fundamental therapies for hereditary hearing loss.
[show abstract][hide abstract] ABSTRACT: We evaluated the expression of the costimulatory molecules CD80 and CD83 and major histocompatibility (MHC) class II induced by 2,4-dinitrofluorobenzene (DNFB) in the RAW 264.7 macrophage cell line. In contrast to the previously reported effect of DNFB on dendritic cells, CD86 expression did not change. Furthermore, we observed that the CD83 expression level transiently increased and then decreased. Induction of CD80 and MHC class II molecule expression and a decrease in CD83 expression by DNFB in vitro were also confirmed in splenocytes of BALB/c and NC/Nga mice. However, DNFB did not influence CD83 expression in peritoneal CD11b+ cells from BALB/c or NC/Nga mice. Detailed in vivo experiments and further studies on the possible contribution of CD11b+ cells to induce atopic dermatitis (AD) would be helpful to attain a better understanding of AD pathogenesis. [BMB Reports 2012; 45(9): 538-543].
[show abstract][hide abstract] ABSTRACT: A number of genes responsible for hearing loss are related to ion recycling and homeostasis in the inner ear. Connexins (Cx26 encoded by GJB2, Cx31 encoded by GJB3 and Cx30 encoded by GJB6) are core components of gap junctions in the inner ear. Gap junctions are intercellular communication channels and important factors that are associated with hearing loss. To date, a molecular genetics study of GJB3 and GJB6 as a causative gene for hearing loss has not been performed in Korea. This study was therefore performed to elucidate the genetic characteristics of Korean patients with nonsyndromic sensorineural hearing loss and to determine the pathological mechanism of hearing loss by analyzing the intercellular communication function of Cx30 and Cx31 variants. Sequencing analysis of the GJB3 and GJB6 genes in our population revealed a total of nine variants, including four novel variants in the two genes. Three of the novel variants (Cx31-p.V27M, Cx31-p.V43M and Cx-30-p.I248V) and two previously reported variants (Cx31-p.V84I and Cx30-p.A40V) were selected for functional studies using a pathogenicity prediction program and assessed for whether the mutations were located in a conserved region of the protein. The results of biochemical and ionic coupling tests showed that both the Cx31-p.V27M and Cx31-p.V84I variants did not function normally when each was expressed as a heterozygote with the wild-type Cx31. This study demonstrated that two variants of Cx31 were pathogenic mutations with deleterious effect. This information will be valuable in understanding the pathogenic role of GJB3 and GJB6 mutations associated with hearing loss.
Biochimica et Biophysica Acta 05/2012; · 4.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: Microsatellites, short tandem repeats, are useful markers for genetic analysis because of their high frequency of occurrence
over the genome, high information content due to variable repeat lengths, and ease of typing. To establish a panel of microsatellite
markers useful for genetic studies for hereditary hearing loss in the Korean population, the allele frequencies and heterozygosities
of 32 microsatellite markers in 172 unrelated Korean individuals were examined. The heterozygosity values for these markers
ranged from 48 to 87%. All the markers except D6S1038 and D14S1034 marker showed PIC values over 0.5. This indicates these
markers have a high degree of polymorphism and are randomly distributed in the Korean population. Therefore, the combinations
of these STR loci provide a powerful tool to find the candidate loci of a causative gens for non-syndromic hearing loss in
the Korean population.
Key wordsshort tandom repeat (STR)-heterozygosity-Korean
[show abstract][hide abstract] ABSTRACT: Yeast ribosomal protein S3 has multifunctional activities that are involved in both protein translation and DNA repair. Here, we report that yeast Rps3p cleaves variously damaged DNA that contains not only AP sites and pyrimidine dimers but also 7,8-hydro-8-oxoguanine. This study also revealed that Rps3p has a β-lyase activity with a broad range of substrate specificity which cleaves phosphodiester bonds of UV or oxidatively damaged DNA substrates. Mutation analysis of the yeast Rps3 protein including introduction of domain deletions and residue replacements identified the residues Asp154 and Lys200 are important for the catalytic activity. In addition, the repair enzyme activity of yeast Rps3p was confirmed by complementation in xth, nfo Escherichia coli cells in which the DNA repair process is defective.
[show abstract][hide abstract] ABSTRACT: Immunostimulatory CpG-DNA targeting TLR9 is one of the most extensively evaluated vaccine adjuvants. Previously, we found that a particular form of natural phosphodiester bond CpG-DNA (PO-ODN) encapsulated in a phosphatidyl-Β-oleoyl- γ-palmitoyl ethanolamine (DOPE) : cholesterol hemisuccinate (CHEMS) (1 : 1 ratio) complex (Lipoplex(O)) is a potent adjuvant. Complexes containing peptide and Lipoplex(O) are extremely useful for B cell epitope screening and antibody production without carriers. Here, we showed that IL-12 production was increased in bone marrow derived dendritic cells in a CpG sequence-dependent manner when PO-ODN was encapsulated in Lipoplex(O), DOTAP or lipofectamine. However, the effects of Lipoplex(O) surpassed those of PO-ODN encapsulated in DOTAP or lipofectamine and also other various forms of liposome-encapsulated CpG-DNA in terms of potency for protein antigen-specific IgG production and Th1- associated IgG2a production. Therefore, Lipoplex(O) may have a unique potent immunoadjuvant activity which can be useful for various applications involving protein antigens as well as peptides.
[show abstract][hide abstract] ABSTRACT: Human ribosomal protein S3 (rpS3) acts as a DNA repair endonuclease. The multiple functions of this protein are regulated by post-translational modifications including phosphorylation and methylation. Using a yeast-two hybrid screen, we identified small ubiquitin-related modifier-1 (SUMO-1) as a new interacting partner of rpS3. rpS3 interacted with SUMO-1 via the N- and C-terminal regions. We also observed sumoylation of rpS3 in Escherichia coli and mammalian cell systems. Furthermore, we discovered that one of three lysine residues, Lys18, Lys214, or Lys230, was sumoylated in rpS3. Interestingly, sumoylated rpS3 was resistant to proteolytic activity, indicating that SUMO-1 increased the stability of the rpS3 protein. We concluded that rpS3 is covalently modified by SUMO-1 and this post-translational modification regulates rpS3 function by increasing rpS3 protein stability.
Biochemical and Biophysical Research Communications 09/2011; 414(3):523-7. · 2.41 Impact Factor
[show abstract][hide abstract] ABSTRACT: Mutations in the gap junction β2 (GJB2) gene, encoding the connexin26 (CX26) protein, are the most common cause of non-syndromic hearing loss (HL) in many populations. In the East Asian population, two variants, p.V27I (c.79G>A) and p.E114G (c.341G>A), are considered benign polymorphisms since these variants have been identified in both HL patients and normal hearing controls. However, some studies have postulated that homozygotes carrying both p.V27I and p.E114G variants could cause HL. To elucidate possible roles of these variants, we used in vitro approaches to directly assess the pathogenicity of four haplotypes generated by the two polymorphisms: VE (wild type), I*E (p.V27I variant only), VG* (p.E114G variant only), I*G* (both variants). In biochemical coupling assays, the gap junctions (GJs) composed of VG* and I*G* types displayed defective channel activities compared with those of VE wild types or I*E types, which showed normal channel activities. Interestingly, the defect in hemichannel activity was a bit less severe in I*G* type than VG* type, suggesting that I* variant (p.V27I) may compensate for the deleterious effect of G* variant (p.E114G) in hemichannel activities. Our population studies using 412 Korean individuals showed that I*G* type was detected at around 20% in both HL patients and normal controls, suggesting that I*G* type may not be a pathogenic polymorphism. In contrast, VG* type was very rare (3/824) and detected only in HL patients, suggesting that VG* homozygotes (VG*/VG*) or compound heterozygotes carrying VG* type with other mutations may cause HL.
Molecular Medicine 01/2011; 17(5-6):550-6. · 4.47 Impact Factor
[show abstract][hide abstract] ABSTRACT: DFN3, the most prevalent X-linked hearing loss, is caused by mutations in the POU3F4 gene. Previous studies in Pou3f4 knockout mice suggest that defective otic fibrocytes in the spiral ligament of the cochlear lateral wall may underlie the hearing loss in DFN3. To better understand the pathological mechanisms of the DFN3 hearing loss, we analyzed inner ears of Pou3f4-deficient mice during development. Our results indicate that compartmentalization of the spiral ligament mesenchyme setting up boundaries for specific otic fibrocytes occurs normally in Pou3f4-deficient cochlea. However, differentiation of the compartmentalized mesenchyme into specific otic fibrocytes was blocked in the absence of Pou3f4 function. In addition, we found that stria vascularis in the cochlear lateral wall was also affected in Pou3f4-deficient cochlea. Unlike the otic fibrocytes, differentiation of stria vascularis was completed in the absence of Pou3f4 function, yet expression of Kir4.1 channels in the strial intermediate cells, essential for the sound transduction, was lost afterwards. These results suggest that Pou3f4 deficiency causes defects in both otic fibrocytes and stria vascularis at different developmental stages and by different pathological mechanisms, which may account for the progressive nature of DFN3 hearing loss.
Biochemical and Biophysical Research Communications 01/2011; 404(1):528-33. · 2.41 Impact Factor
[show abstract][hide abstract] ABSTRACT: Natural phosphodiester bond CpG-DNA that contains immunomodulatory CpG motifs (PO-DNA) upregulates the expression of proinflammatory cytokines and induces an Ag-driven Th1 response in a CG sequence-dependent manner in mice. In humans, only phosphorothioate backbone-modified CpG-DNA (PS-DNA) and not PO-DNA has immunomodulatory activity. In this study, we found that liposome-encapsulated PO-DNA upregulated the expression of human Beta-defensin-2 (hBD-2) and major histocompatibility class II molecules (HLA-DRA) in a CG sequence-dependent and liposome- dependent manner in human B cells. Of the three different liposomes, DOTAP has the unique ability to enhance the immunomodulatory activity of PO-DNA. In contrast, HLA-DRA and hBD-2 promoter activation can be induced by liposomeencapsulated PS-DNA in a CG sequence-independent manner, depending on the CpG-DNA species. Our observations demonstrate that, when encapsulated with a proper liposome in the immune system, natural PO-DNA has the potential to be a useful therapy for the regulation of the innate immune response.
[show abstract][hide abstract] ABSTRACT: Levetiracetam (LEV, 2S-(oxo-1-pyrrolidinyl)butanamide, Keppra, UCB Pharma) is a new anti-epileptic drug used to treat certain types of seizures in epilepsy patients. However, the pharmacodynamics of LEV is still controversial. Recently, interleukin-1 beta (IL-1 beta) has been reported to involve in epileptic phenomena. Therefore, we investigated the effects of LEV on IL-1 beta system in the hippocampus and piriform cortex of chronic epileptic rats. As compared to controls, typical reactive astrogliosis and microgliosis were observed in the hippocampus and piriform cortex of epileptic animals. In addition, both reactive astrocytes and reactive microglia showed strong IL-1 beta and interleukin-1 receptor subtype 1 (IL-1R1) immunoreactivities. LEV reduced reactive gliosis and expression levels of IL-1 beta system in the hippocampus and the piriform cortex, while valproic acid did not. These findings suggest that the LEV may have, at least in part, anti-inflammatory effect, particularly against IL-1 beta system in neuroglia within epileptic brains.
[show abstract][hide abstract] ABSTRACT: Congenital hearing loss (HL) is the most common sensory disorder in humans, affecting one in 1000 infants at birth. A high degree of genetic heterogeneity makes it difficult to screen for mutations in all known deafness genes in clinical applications. We have improved a genotyping microarray using the multiplex PCR-based allele-specific primer extension (ASPE) reaction and applied this method for the genetic diagnosis of congenital HL in Korea. Seven different mutations in the GJB2, SLC26A4 and mitochondrial 12S rRNA genes, which were identified on the basis of a previous study in a Korean population, were selected for the study. These genes were used to evaluate the accuracy of the microarray. The test for validation of the current version of HL genotyping microarray was fully concordant with the results of DNA sequencing in which 51 subjects with non-syndromic HL were originally genotyped. Furthermore, the blind test of the genotyping microarray detected four different mutations in 10 out of 65 patients, and the accuracy of microarray was calculated as 98% (64/65). Therefore, our results suggest that this HL genotyping microarray will be useful in clinical applications for the genetic diagnosis of HL.
International Journal of Molecular Medicine 03/2010; 25(3):315-20. · 1.96 Impact Factor
[show abstract][hide abstract] ABSTRACT: Recessive mutations of the SLC26A4 (PDS) gene on chromosome 7q31 can cause sensorineural deafness with goiter (Pendred syndrome, OMIM 274600) or NSRD with goiter (at the DFNB4 locus, OMIM 600791). H723R (2168A>G) is the most commonly reported SLC26A4 mutations in Korean and Japanese and known as founder mutation. We recently experienced one patient with enlarged vestibular aqueduct syndrome. The genetic study showed H723R homozygous in the proband and H723R heterozygous mutation in his family members. The identification of a disease-causing mutation can be used to establish a genotypic diagnosis and provide important information to both families and their physicians.
Clinical and Experimental Otorhinolaryngology 07/2009; 2(2):100-2. · 0.88 Impact Factor
[show abstract][hide abstract] ABSTRACT: Mutations in the GJB2 gene, which encodes the gap junction (GJ) protein connexin26 (Cx26), are the most common cause of inherited non-syndromic hearing loss (NSHL). We identified two missense mutations, p.D46E (c.138T>G) and p.T86R (c.257C>G), of GJB2 in Korean HL families. The novel p.D46E mutation exhibited autosomal dominant inheritance, while the p.T86R mutation, which is exclusively found in Asians, segregated with an autosomal recessive pattern. Thus, we sought to elucidate the pathogenic nature of such different inherited patterns of HL. We studied protein localization and gap junction functions in cells transfected with wild-type or mutant Cx26 tagged with fluorescent proteins, which allowed visual confirmation of homozygous or heterozygous mutant GJs. The Cx26-D46E mutant was targeted to the plasma membrane, but this mutant protein failed to transfer Ca(2+) or propidium iodide intercellularly, suggesting disruption of both ionic and biochemical coupling. Heterozygous GJs also showed dysfunctional intercellular couplings and hemichannel opening, confirming the dominant-negative nature of the p.D46E mutation. The Cx26-T86R mutant protein did not form GJs, since the mutated protein was confined in the cytoplasm and not transported to the cell membrane. When Cx26-T86R was co-expressed with Cx26-WT, ionic and biochemical coupling was normal, consistent with the recessive nature of the mutation. These studies revealed distinct pathogenic mechanisms of two GJB2 mutations identified in Korean families.
Human Mutation 05/2009; 30(7):E716-27. · 5.21 Impact Factor
[show abstract][hide abstract] ABSTRACT: Hearing loss is the most common sensory disorder in humans and genetic causes are estimated to cause more than 50% of all incidents of congenital hearing loss. To develop an efficient method for a genetic diagnosis of hearing loss, we have developed and validated a genetic hearing loss DNA chip that allows the simultaneous analysis of 7 different mutations in the GJB2, SLC26A4, and the mtDNA 12S rRNA genes in Koreans.
A genotyping microarray, based on the allele-specific primer extension (ASPE) method, was used and preliminary validation was examined from the five patients and five controls that were already known their genotypes by DNA sequencing analysis.
The cutoff Genotyping index (GI) of genotyping for each mutation was set up and validated to discriminate among the genotypes. The result of the DNA chip assay was identical to those of previous results.
We successfully designed the genetic hearing loss DNA chip for the first time in Korea and it would be useful for a clinical genetic diagnosis of hearing loss. Further consideration will be needed in order to examine the accuracy of this DNA chip with much larger patient sample numbers.
Clinical and Experimental Otorhinolaryngology 04/2009; 2(1):44-7. · 0.88 Impact Factor
[show abstract][hide abstract] ABSTRACT: Pyridoxal-5'-phosphate (PLP)-phosphatase/chronophin (PLPP/CIN) directly dephosphorylates actin-depolymerizing factor (ADF)/cofilin as well as PLP. Although PLPP/CIN plays a role in the regulation of F-actin and vitamin B(6) metabolism, there is no direct evidence to support a correlation between PLPP/CIN and F-actin polymerization during long-term potentiation (LTP) induction. In this study, we investigated whether the expression of PLPP/CIN is altered following LTP induction, and whether Tat-PLPP/CIN transduction affects LTP induction in the rat dentate gyrus (DG). PLPP/CIN immunoreactivity was markedly decreased in dentate granule cells after the induction of LTP. Tat-PLPP/CIN transduction (20 and 200 microg/kg) decreased the efficiency of high frequency stimulus-induced potentiation of populations spike amplitude as compared to saline or Tat-protein-treated animals. The PLPP/CIN protein level showed an inverse correlation with phosphorylated ADF/cofilin levels and F-actin content. These findings suggest that PLPP/CIN-mediated actin dynamics may play an important role in the changes of morphological properties (dendritic spine reorganization) of the hippocampus in LTP.
[show abstract][hide abstract] ABSTRACT: Branchio-oto-renal (BOR) syndrome is an autosomal dominant disorder characterized by branchial cleft fistulae or cysts, preauricular pits, ear malformations, hearing loss, and renal anomalies. Mutations in the human homologue of the Drosophilia eyes absent gene (EYA1) are the most common cause of BOR syndrome. In this study, we found a Korean family showing clinical features of the disease. Mutation analysis of the EYA1 gene revealed a novel one-base-pair deletion resulting in truncated protein (c.321delT; p.Ala107fs). This is the first report of BOR syndrome caused by deletion mutation of the EYA1 gene in Korea.
Annals of clinical and laboratory science 02/2009; 39(3):303-6. · 0.88 Impact Factor
[show abstract][hide abstract] ABSTRACT: In this study, we investigated whether the expression of pyridoxal kinase (PLK) and pyridoxine-5'-phosphate oxidase (PNPO) are altered following long-term potentiation (LTP) induction, and whether Tat-PLK and Tat-PNPO transductions affect LTP induction and paired-pulse responses in the rat dentate gyrus (DG). PNPO immunoreactivity was markedly increased in dentate granule cells after the induction of LTP, but that of PLK was not. Tat-PNPO (20 and 200 microg/kg), but not Tat-PLK or vitamin B6 precursors, treatments, increased the efficiency of high frequency stimulus-induced potentiation of populations spike amplitude when compared with saline-, or Tat-protein-treated animals. These changes correlated with the alterations in PNPO activity and its immunoreactivity. In addition, Tat-PNPO transduction increased paired-pulse facilitation but had no effect on the fast and late paired-pulse inhibitions. These findings suggest that PNPO may play a role in activity-dependent regulation of PLP level in the brain, which is involved in LTP induction and paired-pulse facilitation but not in enhancement of GABAergic inhibition.
[show abstract][hide abstract] ABSTRACT: Febrile seizure (FS) is the most common type of seizure that occurs during early childhood. It has been proposed that atypical FS (prolonged, multiple, or lateralized) results in the development of recurrent complex partial seizures accompanied by Ammon's horn sclerosis or mesial temporal sclerosis, which is the most common of the intractable epilepsy. To elucidate the characteristics of epileptogenesis or acquired epilepsy following FS, we performed prospective long-term studies using hyperthermia-induced seizure model. Rat pups (postnatal 11 day old) were induced to hyperthermia (41-43 degrees C in core temperature) by exposure to a 175 W mercury vapor lamp. Six-nine weeks after hyperthermic seizure, the dentate gyrus showed impairments of paired-pulse inhibitions and excitability ratio. In addition, newly generated granule cells and synaptogenesis were observed in this region. Ten-twelve weeks after hyperthermic seizure, animals (approximately 68%) showed electroencephalographic seizure activity with increased VGLUT-1 immunoreactivity in the dentate gyrus. Parvalbumin immunoreactivity was markedly reduced in the hilus. These findings indicate that in this model the epileptogenic changes in the dentate gyrus may be based on the persistent alterations in excitability via neurogenesis, synaptogenesis, and impaired GABA(B) receptor-mediated inhibition.
Brain Research 07/2008; 1216:1-15. · 2.88 Impact Factor
[show abstract][hide abstract] ABSTRACT: Changes in actin dynamics and pyridoxal-5'-phosphate (PLP) metabolisms are closely related to the pathophysiological profiles of the epileptic hippocampus. Recently, it has been reported that PLP phosphatase/chronophin (PLPP/CIN) directly dephosphorylates actin-depolymerizing factor (ADF)/cofilin as well as PLP. In the present study, therefore, we have investigated whether PLPP/CIN is linked to the dynamics of actin filament assembly and the excitability in the rat hippocampus. In control animals, pyridoxine chloride (PNP) treatment increased PLPP/CIN immunoreactivity only in astrocytes, which did not affect electrophysiological properties. Following status epilepticus, the PLPP/CIN protein level increased in granule cells and reactive astrocytes. These changes in PLPP/CIN protein level showed an inverse correlation with phospho-ADF (pADF)/cofilin levels and F-actin content. These changes were also accompanied by alterations in the excitability ratio and paired-pulse inhibition. Transduction of PLPP/CIN by Tat-PLPP/CIN showed similar effects on pADF/cofilin levels, F-actin content and excitability ratio in normal animals. These findings suggest that PLPP/CIN-mediated actin dynamics may play an important role in the changes of morphological properties and excitability of the epileptic hippocampus.