Immunoproteasome induction is suppressed in hepatitis C virus-infected cells in a protein kinase R-dependent manner

By changing the relative abundance of generated antigenic peptides through alterations in the proteolytic activity, interferon (IFN)-γ-induced immunoproteasomes influence the outcome of CD8⁺ cytotoxic T lymphocyte responses. In the present study, we investigated the effects of hepatitis C virus (HCV) infection on IFN-γ-induced immunoproteasome expression using a HCV infection cell culture system. We found that, although IFN-γ induced the transcriptional expression of mRNAs encoding the β1i/LMP2, β2i/MECL-1 and β5i/LMP7 immunoproteasome subunits, the formation of immunoproteasomes was significantly suppressed in HCV-infected cells. This finding indicated that immunoproteasome induction was impaired at the translational or posttranslational level by HCV infection. Gene silencing studies showed that the suppression of immunoproteasome induction is essentially dependent on protein kinase R (PKR). Indeed, the generation of a strictly immunoproteasome-dependent cytotoxic T lymphocyte epitope was impaired in in vitro processing experiments using isolated 20S proteasomes from HCV-infected cells and was restored by the silencing of PKR expression. In conclusion, our data point to a novel mechanism of immune regulation by HCV that affects the antigen-processing machinery through the PKR-mediated suppression of immunoproteasome induction in infected cells.

Allele Distribution and Frequency of Human Surfactant Protein-A2 in Korean Neonates

PURPOSE: We evaluated allele frequencies and distribution of surfactant protein A2(SP-A2) in Korean neonates in order to estimate the prevalence of RDS, to find out new SP-A alleles, and to establish new steroid therapy. METHODS: Genomic DNA was extracted from 71 neonates and served as a template in PCR for genotype analysis. SP-A gene-specific amplications and gene-specific allele determinations were performed using PCR-cRFLP methods. RESULTS: The distribution for the alleles of the SP-A2 gene in the study population was 1A, 1A0, 1A1, 1A2, 1A3, 1A5, 1A6, 1A7, 1A8, 1A9, 1A11, 1A12. The specific frequencies for the alleles of the SP- A2 gene in the study population were : 1A=11.3%, 1A0=38%, 1A1=12.7%, 1A2=9.2%, 1A5=15.5%, 1A7= 2.9%, 1A8=4.9%, 1A9=2.2%, others=3.3%. CONCLUSION: The frequency of 1A0 was higher than the other SP-A2 alleles in Korean neonates. This finding suggests that the prevalence of RDS in Korea may be low compared with other countries. However, this finding also suggests that Korean neonates have a high risk of infection.

Allele Distribution and Frequency of Human Surfactant Protein-A1 in Korean Neonates

PURPOSE: We evaluated allele frequencies and distribution of surfactant protein A1(SP-A1) in Korean neonates in order to estimate prevalence of RDS to find out new SP-A alleles, and to establish new steroid therapy. METHODS: Genomic DNA was extracted from 100 neonates and served as a template in PCR for genotype analysis. SP-A gene-specific amplications and gene-specific allele determinations were performed using PCR-RFLP methods. RESULTS: The distribution for the alleles of the SP-A1 gene in the study population were 6A, 6A(2), 6A(3), 6A(4), 6A(8), 6A(9), 6A(10), 6A(11), 6A(12), 6A(13), 6A(14), 6A(15), 6A(16), 6A(17), 6A(18), 6A(20). The specific frequencies for the alleles of the SP-A1 gene in the study population were: 6A(2)=21%, 6A(3)=45%, 6A(4)=11%, 6A(8)=9%, 6A(14)=8%. CONCLUSIONS: The frequency of 6A3 was higher than the other SP-A1 alleles in Korean neonates. This finding suggests that the prevalence of RDS in Korea may be low compared with other countries. However, this finding also suggests that Korean neonates have a high risk of infection.

Effect of metal ions on the stability of metallothionein in the degradation by cellular fractions in vitro

Metallothioneins (MT), small molecular weight metal binding proteins are known to play an important protective role against heavy metal toxicity, either as antioxidants or pre-oxidants. However, the mode of metabolic fate of MTs in various metal complexes is not clearly understood. This study was carried out to better understand the mode of selective turnover rate of various form of MT in complexes with different metals. The degradation of in vitro translated mouse 35S-cysteine-MT was examined in lysosomal or cytosolic fractions from mouse liver by gel electrophoresis and autoradiography. Overnight incubations of MT showed extensive proteolysis in the lysosomal fraction but not in cytosolic fractions. However, Cu2+-MT was found to be stable under the same experimental condition. In contrast, Zn did not interfere with MT degradation. These results suggest that lysosomes are chiefly responsible for MT removal and appears to be selective on the metals involved in the MT complex. In vitro, translated, radiolabeled MT provides a suitable substrate for investigating the characteristics of MT degradation.

Immunohistochemical Study of Expression of Acid Stable Trypsin Inhibitor ( ASTI ) in Premalignant and Malignant Skin Tumors / 대한피부과학회지

BACKGROUND: Recently, much attention has been focused on the role of protease inhibitors such as acid stable trypsin inhibitor (ASTI) in the invasive growth of malignant tumors. However, there are no report on expression of ASTI from premalignant and/or malignant skin tumors. OBJECTIVES: In the present study the expression of ASTI was investigated in the different type of premalignant and/or, malignant skin tumors in attempt to clarify the relation between the expression of the ASTI and malignancy. METHODS: For the detection of ASTI in the tumor tissue, the immunoperoxidase techniques that used mouse antibody raised against highly purified ASTI. The degree of ASTI immunoreactivity was semiquantitatively assessed for staining intensity as the percentage of ASTI-positive cells. RESULTS: ASTI immunoreactivity was detected in most of the premalignant and malignant skin tissues. Especially, ASTI expression was present widespread in squamous cell carcinoma(SCC) with strong cytoplasmic membrane, where as in normal epidermis they were primarily present in the horny layer. The strong staining was the SCC, keratoacanthoma, Bowen's disease, actinic keratosis, basal cell epithelioma, Paget's disease in decreasing order. The significant difference in the staining intensity was observed between SCC and other groups. CONCLUSION: Results of immunohistochemical studies suggest that the tumor cells themselves could produce ASTI. Considering the suggestion that ASTI is a self protector, inhibitor to proteolytic protease as well as growth-stimulating factor. The present findings may indicate that ASTI expressed in malignant cells may play a role possibly closely associated with tumor development.