• BMB Reports
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• 제42권2호
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• pp.113-118
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• 2009

Despite the growing body of evidence suggesting a role for MsrA in antioxidant defense, little is currently known regarding the function of MsrB in cellular protection against oxidative stress. In this study, we overexpressed the mammalian MsrB and MsrA genes in Saccharomyces cerevisiae and assessed their subcellular localization and antioxidant functions. We found that the mitochondrial MsrB3 protein (MsrB3B) was localized to the cytosol, but not to the mitochondria, of the yeast cells. The mitochondrial MsrB2 protein was detected in the mitochondria and, to a lesser extent, the cytosol of the yeast cells. In this study, we report the first evidence that MsrB3 overexpression in yeast cells protected them against $H_2O_2$-mediated cell death. Additionally, MsrB2 overexpression also provided yeast cells with resistance to oxidative stress, as did MsrA overexpression. Our results show that mammalian MsrB and MsrA proteins perform crucial functions in protection against oxidative stress in lower eukaryotic yeast cells.

• Reproductive and Developmental Biology
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• 제28권3호
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• pp.147-153
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• 2004

The oocyte and its surrounding granulosa cells co-exist in a closed compartment called a follicle, although they receive many signals from other parts of the body. It is well established that the intercellular communications between the oocyte and granulosa cells are required for normal oocyte development and ovulation during folliculogenesis. Gap junctions are intercellular channels allowing the direct transmission of ions and small molecules between coupled cells. Several lines of studies have shown that multiple connexins (Cx, subunits of gap junction) are expressed in mammalian ovarian follicles. Among them, two major connexins Cx37 and Cx43 are expressed in different manner. While the gap junction channels formed by Cx37 are localized between the oocyte and encompassing granulosa cells, the intercellular channels by Cx43 are located between granulosa cells. In this review, I will summarize the general properties of gap junction channels and discuss their possible formation (or compatibility) of intercellular channels formed by the oocyte and granulosa cells.

• Reproductive and Developmental Biology
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• 제35권3호
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• pp.251-256
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• 2011

Human growth hormone (hGH), one of the most important hormones in medicine, is secreted from anterior pituitary gland. Its broad physiological function includes body growth, cell regeneration, increasement of muscle volume, bone density, body fat reduction, and so on. Due to the wide range of therapeutic effects, the hGH produced from E. coli has been commercialized already. In this study, we asked whether it is possible to produce recombinant hGH efficiently from various cultured mammalia cells. To meet this purpose, we chose a retrovirus vector system for transfer and expression of the hGH gene in various mammalian cells. Analyses of RT-PCR, ELISA, and Western blot to determine expression of the hGH gene showed the highest production of the hGH was determined from chicken embronic fibroblast (CEF) cells with the concentration of 8.58 ${\mu}g$/ml. The biological activity of the hGH was similar to the commercially available counterpart. These results suggest that mass production of hGH is possible not only in the E. coli but also in the various mammalian cells.

• BMB Reports
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• 제36권4호
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• pp.390-398
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• 2003

The CDP/Cux transcription factor was previously shown to be proteolytically processed at the G1/S transition. In view of characterizing and eventually identifying the protease responsible for CDP/Cux processing, we have established an in vitro proteolytic processing assay. CDP/Cux recombinant proteins expressed in mammalian or bacterial cells were efficiently processed in vitro using as a source of protease either whole cell extracts, the nuclear or the cytoplasmic fraction. Processing was found to take place optimally at a lower pH, to be insensitive to variations in salt concentration, and to be inhibited by the protease inhibitors MG132 and E64D. Interestingly, the bacterially-produced substrate was more efficiently processed than the substrate purified from mammalian cells. Moreover, processing in vitro was more efficient when CDP/Cux substrates were purified from populations of cells enriched in the S phase than in the G1 phase of the cell cycle. Altogether, these results suggest that post-translational modifications of CDP/Cux in mammalian cells inhibits processing and contributes to the cell cycle-dependent regulation of processing. The in vitro processing assay described in this study will provide a useful tool for the purification and identification of the protease responsible for the processing of CDP/Cux.

• Toxicological Research
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• 제27권1호
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• pp.25-29
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• 2011

The cytochrome P450 (P450, CYP) are the superfamily of heme-containing monooxygenase enzymes, found throughout all nature including mammals, plants, and microorganisms. Mammalian P450 enzymes are involved in oxidative metabolism of a wide range of endo- and exogenous chemicals. Especially P450s involved in drug metabolisms are important for drug efficacy and polymorphisms of P450s in individuals reflect differences of drug responses between people. To study the functional differences of CYP2A6, CYP2D6, and CYP4A11 variants, we cloned the four CYP2A6, three CYP2D6, and three CYP4A11 variants, which were found in Korean populations, in mammalian expression vector pcDNA by PCR and examined their expressions in COS-7 mammalian cells using immunoblots using P450 specific polyclonal antibodies. Three of four CYP2A6, two of three CYP4A11, and two of three CYP2D6 variants showed expressions in COS-7 cells but the relative levels of expressions are remarkably different in those of each variants. Our findings may help to study and explain the differences between functions of CYP variants and drug responses in Korean populations.

• Asian Pacific Journal of Cancer Prevention
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• 제13권8호
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• pp.3695-3700
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• 2012

Mammalian mediator (MED) is a multi-protein coactivator that has been identified by several research goups. The involvement of the MED complex subunit 19 (MED 19) in the metastasis of lung adenocarcinoma cell line (H1299), which expresses the MED 19 subunit, was here investigated. When MED 19 expression was decreased by RNA interference H1299 cells demonstrated reduced clone formation, arrest in the S phase of the cell cycle, and lowered metastatic capacity. Thus, MED 19 appears to play important roles in the biological behavior of non-small cell lung carcinoma cells. These findings may be important for the development of novel lung carcinoma treatments.

• 대한의생명과학회지
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• 제11권2호
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• pp.103-108
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• 2005

2-Deoxyribonolactone (dL) arises as a major DNA damage induced by a variety of agents, involving free radical attack and oxidation of C1'-deoxyribose in DNA. We investigated whether dL lesions can be repaired in mammalian cells and the mechanisms underlying the role of DNA polymerase $\beta$ in processing of dL lesions. Pol $\beta$ appeared to be trapped by dL residues, resulting in stable DNA-protein cross-links. However, repair DNA synthesis at site-specific dL sites occurred effectively in cell-free extracts, but predominantly accompanied by long-patch base excision repair (BER) pathway. Reconstitution of long-patch BER demonstrated that FEN1 was capable of removing the displaced flap DNA containing a 5'-dL residue. Cellular repair of dL lesions was largely dependent on the DNA polymerase activity of Pol $\beta$. Our observations reveal repair mechanisms of dL and define how mammalian cells prevent cytotoxic effects of oxidative DNA lesions that may threaten the genetic integrity of DNA.

• Molecules and Cells
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• 제37권1호
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• pp.1-8
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• 2014

Mammalian-cell messenger RNAs (mRNAs) are generated in the nucleus from precursor RNAs (pre-mRNAs, which often contain one or more introns) that are complexed with an array of incompletely inventoried proteins. During their biogenesis, pre-mRNAs and their derivative mRNAs are subject to extensive cis-modifications. These modifications promote the binding of distinct polypeptides that mediate a diverse array of functions needed for mRNA metabolism, including nuclear export, inspection by the nonsense-mediated mRNA decay (NMD) quality-control machinery, and synthesis of the encoded protein product. Ribonucleoprotein complex (RNP) remodeling through the loss and gain of protein constituents before and after pre-mRNA splicing, during mRNA export, and within the cytoplasm facilitates NMD, ensuring integrity of the transcriptome. Here we review the mRNP rearrangements that culminate in detection and elimination of faulty transcripts by mammalian-cell NMD.

• 한국환경성돌연변이발암원학회지
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• 제24권3호
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• pp.143-150
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• 2004

In mammalian, cytochrome P4501A1 (CYP1A1) is very important for metabolism of xenobiotics such as PAHs(Polycyclic aromatic hydrocarbon) and heterocyclic amine, and it is induced by environmental contaminants such as PAHs, TCDD(2,3,7,8-tetrchlorodibenzo-p-dioxin) and 3-MC (3-methylcholanthrene). In fish, like mammalian, when it is exposed to environmental contaminants, they cause specific and sensitive induction of CYP1A. Therefore, induction of CYP1A in fish and mammalian is widely used as a biomarker for exposure of environmental contaminants. In this study, to compare the function of Cyp1a1 in fish with it in mammalian, we have used rainbow trout(Oncorhynchys mykiss) hepatoma cells (RTH-149) and mouse hepatocyte (Hepa-I). in order to examine induction of Cyp1a1 by TCDD, we have used the bioassay system. We examined effects of TCDD on the Cyp1a1-luciferase reporter gene activity, 7-ethoxyresorufin O-deethylase(EROD) activity and Cypa mRNA level.

• 대한바이러스학회지
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• 제29권3호
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• pp.183-193
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• 1999

Human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein is synthesized as a 160 KDa precursor, gp160, that is cleaved by a cellular protease to form the gp120 and gp41 subunits. Mammalian expression vectors were designed that are capable of efficient expression of various mutant envelope glycoproteins derived from a molecular clone of HIV-1. To construct these vectors, one type of mutation was made at the gp120-gp41 cleavage site by oligonucleotide-directed mutagenesis. And another mutation was made to change amino acids in the membrane spanning region of HIV-1 gp41 important for membrane anchorage. Next, these two mutations were combined to generate a vector to have double mutations in cleavage site and membrane-spanning region. These mutants were transiently expressed in mammalian cells. The effect of these mutations on envelope glycoprotein synthesis, proteolytic processing and secretion was determined. In addition, cell surface expression and ability of the glycoprotein to induce syncytium formation were examined. This study provides a mammalian expression system that is capable of efficient expression and secretion of soluble gp160.