• Proceedings of the Korean Society of Applied Pharmacology
• /
• 2006.04a
• /
• pp.77-90
• /
• 2006

Beta-amyloid peptide (A$\beta$) is a major component of senile plaques and its aggregation is considered to play a critical role in pathogenesis of Alzheimer's disease (AD). Aggregation of A$\beta$ could result from both increased synthesis and decreased degradation of A$\beta$. Our laboratory is interested in understanding the mechanism of A$\beta$ degradation in brain. Recently our laboratory identified a bacterial gene (SKAP) from Streptomyces sp KK565 whose protein product has an activity to cleave A$\beta$ and thus reduce the A$\beta$-induced neurotoxicity. The sequence analysis showed that this gene was closely related to aminopeptidase. Maldi-Tof analysis showed that the recombinant SKAP protein expressed in E. coli cleaves both A$\beta$ 40 and A$\beta$ 42 at the N-terminal of A$\beta$ while an aminopeptidase from Streptomyces griseus (SGAP) cleaves at the C-terminal. We also identified a mammalian homolog of SKAP and the recombinant mammalian protein expressed in Sf-9 insect cells showed a similar proteolytic activity to SGAP, cutting A$\beta$ at the C-terminus. I well discuss the detailed mechanism of the enzyme action and its functional implication in AD.

• BMB Reports
• /
• v.54 no.8
• /
• pp.413-418
• /
• 2021

ErbB3-binding protein 1 (EBP1) is a multifunctional protein associated with neural development. Loss of Ebp1 leads to upregulation of the gene silencing unit suppressor of variegation 3-9 homolog 1 (Suv39H1)/DNA (cytosine 5)-methyltransferase (DNMT1). EBP1 directly binds to the promoter region of DNMT1, repressing DNA methylation, and hence, promoting neural development. In the current study, we showed that EBP1 suppresses histone methyltransferase activity of Suv39H1 by promoting ubiquitin-proteasome system (UPS)-dependent degradation of Suv39H1. In addition, we showed that EBP1 directly interacts with Suv39H1, and this interaction is required for recruiting the E3 ligase MDM2 for Suv39H1 degradation. Thus, our findings suggest that EBP1 regulates UPS-dependent degradation of Suv39H1 to govern proper heterochromatin assembly during neural development.

• Korean Journal of Poultry Science
• /
• v.49 no.4
• /
• pp.265-272
• /
• 2022

Many studies on poultry have been conducted in the poultry industry to improve their important economic traits, such as egg production, meat quality, and carcass yield. Environmental changes affect the poultry's economic traits, including muscle growth. The purpose of this study is to investigate the mechanisms by which simvastatin causes muscle injury in quail muscle cells. Following treatment with various doses of simvastatin, LD50 in the quail myoblast cells was determined using a cell viability test; cell death was caused by apoptosis and/or necrosis. Thereafter, the expression patterns of the atrophy marker genes were examined via quantitative reverse-transcription polymerase chain reaction (qRT-PCR). The results showed that the transcriptional levels of the muscle atrophy marker genes (Atrogin-1, TRIM63) and the upstream genes in their signaling cascade were increased by simvastatin treatment. This indicated that simvastatin induced myogenic cell death and muscle injury via protein degradation through muscle atrophy signaling. Further studies should focus on identifying the mechanism by which simvastatin induces the protein degradation signaling pathway in quail muscle..

• Molecules and Cells
• /
• v.40 no.7
• /
• pp.441-449
• /
• 2017

Proteolysis in eukaryotic cells is mainly mediated by the ubiquitin (Ub)-proteasome system (UPS) and the autophagy-lysosome system (hereafter autophagy). The UPS is a selective proteolytic system in which substrates are recognized and tagged with ubiquitin for processive degradation by the proteasome. Autophagy is a bulk degradative system that uses lysosomal hydrolases to degrade proteins as well as various other cellular constituents. Since the inception of their discoveries, the UPS and autophagy were thought to be independent of each other in components, action mechanisms, and substrate selectivity. Recent studies suggest that cells operate a single proteolytic network comprising of the UPS and autophagy that share notable similarity in many aspects and functionally cooperate with each other to maintain proteostasis. In this review, we discuss the mechanisms underlying the crosstalk and interplay between the UPS and autophagy, with an emphasis on substrate selectivity and compensatory regulation under cellular stresses.

• Journal of Chest Surgery
• /
• v.50 no.3
• /
• pp.153-162
• /
• 2017

Background: The mesenchymal-epithelial transition factor (MET) receptor can be overexpressed in solid tumors, including small cell lung cancer (SCLC). However, the molecular mechanism regulating MET stability and turnover in SCLC remains undefined. One potential mechanism of MET regulation involves the C-terminus of Hsp70-interacting protein (CHIP), which targets heat shock protein 90-interacting proteins for ubiquitination and proteasomal degradation. In the present study, we investigated the functional effects of CHIP expression on MET regulation and the control of SCLC cell apoptosis and invasion. Methods: To evaluate the expression of CHIP and c-Met, which is a protein that in humans is encoded by the MET gene (the MET proto-oncogene), we examined the expression pattern of c-Met and CHIP in SCLC cell lines by western blotting. To investigate whether CHIP overexpression reduced cell proliferation and invasive activity in SCLC cell lines, we transfected cells with CHIP and performed a cell viability assay and cellular apoptosis assays. Results: We found an inverse relationship between the expression of CHIP and MET in SCLC cell lines (n=5). CHIP destabilized the endogenous MET receptor in SCLC cell lines, indicating an essential role for CHIP in the regulation of MET degradation. In addition, CHIP inhibited MET-dependent pathways, and invasion, cell growth, and apoptosis were reduced by CHIP overexpression in SCLC cell lines. Conclusion: C HIP is capable of regulating SCLC cell apoptosis and invasion by inhibiting MET-mediated cytoskeletal and cell survival pathways in NCI-H69 cells. CHIP suppresses MET-dependent signaling, and regulates MET-mediated SCLC motility.

• Asian-Australasian Journal of Animal Sciences
• /
• v.20 no.10
• /
• pp.1517-1524
• /
• 2007

The [$^2H_5$]phenylalanine model was compared with the [1-$^{13}C$]leucine method to determine whole body protein synthesis (WBPS) and degradation (WBPD) in sheep fed at two levels. The animals were fed either 103 (M-diet) or 151 (H-diet) kcal $ME/kg^{0.75}/day$ once daily in a crossover design for 21 days each. The isotope dilutions were simultaneously conducted as a primed-continuous infusion of [$^2H_5$]phenylalanine, [$^2H_2$]tyrosine and [1-$^{13}C$]leucine on each dietary treatment. The WBPS and WBPD calculated from the [$^2H_5$]phenylalanine model were lower (p = 0.009 and p = 0.003, respectively) than those calculated from the [1-$^{13}C$]leucine method. The WBPS tended to be higher (p = 0.08) and WBPD was numerically higher (p = 0.33) for H-diet than M-diet in the [$^2H_5$]phenylalanine model, whereas the WBPS was numerically higher (p = 0.37) for H-diet and WBPS remained similar (p = 0.79) between diets in the [1-$^{13}C$]leucine method. However, the absolute values and the directions of WBPS as well as WBPD from M-diet to H-diet were comparable between the [$^2H_5$]phenylalanine model and [1-$^{13}C$]leucine method. Moreover, the values vary depending on the use of the respective amino acid contents in the carcass protein when calculating WBPS and WBPD. Therefore, it is concluded that the [$^2H_5$]phenylalanine model could be used as an alternative to the [1-$^{13}C$]leucine method for the determination of WBPS and WBPD in sheep.

• Asian-Australasian Journal of Animal Sciences
• /
• v.9 no.6
• /
• pp.637-642
• /
• 1996

This experiment was conducted to determine RDP values of locally available feedstuffs that are commonly used in ruminant rations in Bangladesh. Four cattle were fistulated in the rumen for the in situ nylon bag studies. Seventeen different feedstuff sample (9 roughages and 8 concentrates) were evaluated in $4{\times}14cm$ nylon bags and incubated in the rumen for different periods of time (2, 6, 12, 24, 48 and 72 h). The variation in crude protein (CP) contents reflected on the average CP disappearance value throughout the rumen incubation. Soluble fraction (a), insoluble but degradable fraction (b) along with the rate of degradation also varied widely among the various feedstuffs. Under 2% of rumen outflow rate, the percentages of the calculated protein degradabilities of roughages were rice straw, 16.7; maize grass, 70.6; oat grass, 70.8; dhal grass, 71.1; sunhemp, 78.4; napier grass, 62.4; matikalai grass, 72.1; khesarikalai grass, 76.9 and daincha browse, 78.4, respectively. The results in the protein degradabilities (%) in 8% ruminal outflow rate of concentrates were wheat bran, 61.6; rice polish (red), 61.3; rice polish (auto), 30.9; mustard oil cake, 71.8; sesame oil cake, 74.2; coconut oil cake, 57.9; soybean meal, 49.2 and fish meal, 37.9, respectively.

• Proceedings of the Korean Society of Embryo Transfer Conference
• /
• 2002.11a
• /
• pp.116-116
• /
• 2002

Further development of reconstructed embryos may be dependent upon the synchronization of donor nucleus and recipient cytoplasm at cell fusion, To control the synchronization of donor and recipient cells, the enucleated MII arrested oocytes are artificially stimulated prior to embryo reconstruction. Destruction of cyclin B results in the exit of cells from M-phase of cell cycle. This study was designed to investigate the effects of single or combined stimulation affected cyclin B1 mRNA and protein levels in mouse oocytes. The oocyte activation was induced by 7% ethanol or 10$\mu\textrm{g}$/$m\ell$ Ca-ionophore without (single) or with (combined) 10$\mu\textrm{g}$/$m\ell$ cycloheximide. Competitive quantitative PCR for cyclin Bl mRNA and western blot analysis for cyclin B1 protein was preformed in mouse oocytes. Cyclin B1 mRNA level was significantly reduced in single (P<0.05) and combined (P<0.05) stimulation groups. However, this level did not change in non-activated group and increased in intact group. Cyclin B1 protein level was also significantly reduced in both single (P<0.05) and combined (P<0.05) stimulation groups. In conclusion, single and combined stimulation induces the degradation of cyclin B1 mRNA and protein after activation in enucleated mouse oocytes.

• Preventive Nutrition and Food Science
• /
• v.10 no.4
• /
• pp.378-381
• /
• 2005

Actin and myosin solutions and fresh ground pork were irradiated with the electron beam (e-beam) at a dose of 0, 1.5, 3.0, 5.0 and 10 kGy. The changes in SDS-PAGE pattern of 2 proteins and the salt-soluble proteins extracted from ground pork after e-beam irradiation were monitored. When the myosin solution was irradiated with e-beam, myosin was degraded completely. Complete myosin degradations were observed even with the lowest dose (1.5 kGy) of e-beam treatment. Actin was degraded with the irradiation, but to a less extent than myosin was. The degradation of actin increased as the e-beam treatment increased from 1.5 to 10.0 kGy. Among the salt-soluble proteins extracted from ground pork, myosin was degraded gradually when the e-beam dose increased from 1.5 up to 10.0 kGy. Similar gradual increase in the degradation of actin also occurred with the increase of irradiation. Increases of 2 low molecular weight compounds (<29 kDa) were observed when the irradiation dose increased from 1.5 to 10.0 kGy. These 2 molecules are thought to be the breakdown products produced from the degradation of major salt-soluble proteins, myosin and actin. The salt-soluble protein content of ground pork did not change with the e-beam irradiation.

• KSBB Journal
• /
• v.8 no.1
• /
• pp.42-48
• /
• 1993

Continuous degradation of formaldehyde by using a rotating disc contactor was investigated in this study. Peudomonas putida H-5K was selected as a mutant using N-methyl N'-nitro N-nitrosoguandine (250$\mu\textrm{g}$/$m\ell$), which showed 1.5 times higher ability of formaldehyde degradation than that of the parent strain. Enzyme activity for formaldehyde degradation released form Peudomonas putida H-5K showed the highest level of 6.2mo1/min/mg protein in the 2% glucose mineral medium containing 0.02% formaldehyde. Degradation of formaldehyde from the first stage in rotating disc contactor was 95% and 5% from the 4th stage when the reactor was fed with 0.02% or 0.04% formaldehyde solution at a rate of 20$m\ell$ per hour. Continuous degradation of formaldehyde using rotating disc contactor was above 95%o in the medium containing 0.04% formalchyde, at the medium feed ratc of 20$m\ell$ per hour.