• Molecules and Cells
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• v.24 no.3
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• pp.445-451
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• 2007

Translation initiation factor 4E (eIF4E) is a key regulator of protein synthesis. Abnormal regulation of eIF4E is closely linked to oncogenic transformation. Several regulatory mechanisms affecting eIF4E are discussed, including transcriptional regulation, phosphorylation and binding of an inhibitor protein. However it is not clear how the level of eIF4E protein is regulated under basal conditions. Here we demonstrate that Diap1 (Drosophila Inhibitor of Apoptosis Protein), a cell death inhibitor, binds directly to eIF4E and poly-ubiquitinates it via its E3 ligase activity, promoting its proteasome-dependent degradation. Expression of Diap1 caused a reduction of Cyclin D1 protein level and inhibited the growth stimulation induced by overexpression of eIF4E. Taken together, our results suggest that the level of eIF4E protein is regulated by Diap1, and that IAPs may play a role in cap-dependent translation by regulating the level of eIF4E protein.

• BMB Reports
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• v.34 no.6
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• pp.496-501
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• 2001

Lincomycin, an inhibitor of plastid protein synthesis, was found to block the synthesis of apoprotein P700 with a molecular mass of 72 kDa and the assembly of the Chl a-protein of PS I. Synthesis of the polypeptides of 48, 43.5, and 32 kDa of the PS II complex is also suppressed. This process is accompanied by the disappearance of the PS Two reaction center Chl a at 683 nm, and of the PS One reaction center Chl a at 690, 696, and 705 nm on the fourth derivative of the absorption spectra at 77K. Lincomycin does not affect the synthesis of LHC subunits. It increases the content of the two main Chl forms of LHC at 648 nm (Chl b) and 676 nm (Chl a). The low-temperature fluorescence ratio F736/F685 is also increased. However, the effect of cycloheximide (an inhibitor of cytoplasmic protein synthesis) leads to the reduction of polypeptides of the light-harvesting Chl a/b-protein complex in the range of 29.5-22 kDa. Under these conditions, the relative amount of Chl b and the F736/ F685 fluorescence ratio decrease significantly. This is obviously the result of blocking the LHC I and LHC II synthesis. At the same time rifampicin and actinomycin D (inhibitors which block transcription in chloroplast and nuclear genome, respectively) inessentially affect the characteristics of these complexes.

• Korean Journal of Microbiology
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• v.28 no.4
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• pp.297-303
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• 1990

Secretion of Serratia marcescens nuclease by E. coli harboring pNUC4 was investigated. 29.2, 54.2 and 16.6% of total nuclease were observed in culture medium, periplasm, and cytoplasm of E. coli, respectively. To investigate the secretion mechanism of Serratia nuclease by E. coli, secretion kinetics of nuclease was examined in the presences of sodium azide, and energy metabolism inhibitor; procaine, an exoprotein processing inhibitor; and chloramphenicol, a protein synthesis inhibitor. In the presence of sodium azide, periplasmic unclease was gradually decreased and the extracellular nyclease was linearly increased according to the incubation time. Similar results were obtained in presences of procaine and chloramphenicol. From these results, we concluded that two transport processes are involved in nuclease secretion: secretion of nuclease through the inner membrane is occurred by an energy-dependent process and probably requiring precusor processing: secretion of nuclease through outer membrane does not require energy, de novo protein synthesis, and precursor processing.

• Journal of Life Science
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• v.17 no.10
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• pp.1361-1367
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• 2007

I investigated the effect of KT5720, an inhibitor of protein kinase A, on the vesicular stomatitis virus (VSV) infection in BHK-21cell cultures. The virus inducted cytopathic effect (CPE) was almost completely suppressed by KT5720 at 5uM. The inhibitor, however, did not affect replication of the virus nor the synthesis of viral macromolecules. KT5720, did not block the cytoskeletal disruption, while the cell rounding was suppressed. And, the KT5720-sensitive function may be involved in developing the VSV-induced CPE, but not essential for the virus replications.

• Clinical and Experimental Reproductive Medicine
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• v.22 no.2
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• pp.191-201
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• 1995

Transcriptional activation of the embryonic genome initiates at 2-cell stage in mouse embryo and is characterized by the synthesis of TRC which is restricted to 2-cell stage. To investigate the roles of various protein kinases on the embryonic gene activation, the effects of protein kinase inhibitors on in vitro development and protein synthetic profiles of the early mouse embryos were examinded. None of ${\alpna}-amanitin$ which is a mRNA synthetic inhibitor, H8 which is a PKA inhibitor, and H7 which is a PKC inhibitor, affected on first cleavage of mouse 1-cell embryos in vitro. However, all of these drugs inhibited the second cleavage. When the drugs were removed following treatment for 6 hours, H8 or H7 treatment showed little inhibition on subsequent development of 1-cell embryos to 2-cell stage or further. In contrast, ${\alpna}-amanitin$ irreversibly inhibited the development of 1-cell embryos to 2-cell stage following removal of the drug. Genistein, a TPK inhibitor, inhibited both the first cleavage of 1-cell embryos and the second cleavage of 2-cell embryos, suggesting that TPK activity may be important during the early cleavages. All of the above four drugs inhibited TRC synthesis as shown by the fluorographic analysis of $[^{35}S]-Met$ labeled protein profiles. When late 1-cell embryos were treated with H7 and analyzed synthetic patterns of $[^{35}S]-Met$ labeled protein, the quantitative differences of protein synthesis on SDS-PAGE appeared on 77 kD and 33 kD region at $32{\sim}38$ hours post hCG. From these studies, transcriptional activation of embryonic genome is not essenting to the mouse 1-cell embryos to develop to 2-cell stage. Hawever, TPK activity is reguisite for both the first cleavage and second cleavage. Similarly, both PKC and PKA activities are required for the second cleavage of mouse embryos, but not for the first cleavage.

• Korean Journal of Environmental Agriculture
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• v.20 no.5
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• pp.310-316
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• 2001

To find out the effect of low temperature on the regulation of tomato chloroplast genes, the optimization of the system in chloroplast protein synthesis and the identification of the changes in chloroplast protein synthesis induced by chilling were studied. Incorporation reaction occurred rapidly at the first 30 minutes and was constantly maintained after 60 minutes. A broad optimal temperature on protein synthesis was found around 20 to $30^{\circ}C$. No difference was shown in the chloroplast protein synthesis under high light intensity (1600 ${\mu}E/m^2/s$) as well as under low light intensity (400 ${\mu}E/m^2/s$) even darkness. $K^+$, $Mg^{++}$ and ATP at an optimal concentration act as an activator, while DTT, chloramphenicol, cycloheximide, $Ca^{++}$ and inorganic phosphate act as an inhibitor in the chloroplast protein synthesis. Synthesis of 15, 55 and 60 kd chloroplast encoded stromal proteins and 18, 24, 33 and 55 kd chloroplast encoded thylakoid membrane proteins were reduced by chilling, while 17 kd chloroplast encoded stromal protein and 16 kd chloroplast encoded thylakoid membrane protein was induced by chilling. It was expected that the 55 kd stromal protein would be the large subunit of rubisco and the 33 kd thylakoid membrane protein would be the D1 protein which was drastically reduced by chilling.

• Development and Reproduction
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• v.4 no.1
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• pp.29-35
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• 2000

A phosphatidylinositol 3-kinase (PI3K) is a upstream component of insulin signaling by which protein synthesis can be stimulated in many systems. To elucidate involvement of PI3K and its downstream mammalian target of rapamycin (mTOR) in the insulin signaling in pleimplantation mouse embryos, 8-cell embryos were cultured to blastocysts in the presence or absence of insulin and／or inhibitor drugs. The number of blastomeres per blastocyst, protein synthesis, and protein phosphorylation were examined. There was significant difference in embryonic development to blastocyst stage and hatching was potentiated by the insulin supplementation. The increase in the mean celt numbers per blastocyst was apparent in the insulin culture. Wortmannin, a PI3K inhibitor and rapamycin, an inhibitor of mTOR abolished the stimulatory effect of insulin on morphological development mitosis and protein synthesis. In autoradiography, phosphoproteins pp22 and pp30 which undergo phosphorylation in response to insulin were identified. Taken together, it can be suggested that PI3K and mTOR engaged in insulin signaling in the mouse embryo 8-cell onward and mediate embryotropic offset of insulin.

• Journal of Microbiology and Biotechnology
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• v.5 no.3
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• pp.154-157
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• 1995

MRK-22, an inhibitor of aminopeptidase M was isolated from the culture broth of Streptomyces sp. SL20209. The structure of MRK-22 was defined to be 3-amino-2-hydroxy-5-methylhexanoyl-valyl-valine, des-$Asp^4$-amastatin, by spectroscopic analysis and this was also confirmed by solid phase synthesis of the inhibitor. The molecular formula and weight of MRK-22 were $C_17H_33N_3O_5$ and MW 359($M^+$), respectively, and its $IC_50$ value against hog kidney AP-M was 0.79 $\mu$ g/ml.

• Journal of Nutrition and Health
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• v.49 no.1
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• pp.59-62
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• 2016

Purpose: Zinc, a biomineral present within and outside cells, manages various cellular mechanisms. In this study, we examined whether zinc was involved in vascular smooth muscle cell (VSMC) calcification via regulation of calcification inhibitor protein, osteopontin (OPN). Methods: Rat aorta cell line (A7r5 cells) and primary vascular smooth muscle cells (pVSMCs) from rat aorta were cultured with phosphate (1-5 mM) and zinc ($0-15{\mu}M$) as appropriate, along with osteoblasts (MC3T3-E1) as control. The cells were then stained for Ca and P deposition for calcification examination as well as osteopontin expression as calcification inhibitor protein was measured. Results: Both Ca and phosphate deposition increased as the addition of phosphate increased. In the same manner, the expression of osteopontin was upregulated as the addition of phosphate increased in both cell types. When zinc was added, Ca and P deposition decreased in VSMCs, while it increased in osteoblasts. Conclusion: The results imply that zinc may prevent VSMC calcification by stimulating calcification inhibitor protein OPN synthesis in VSMCs.

• Journal of Microbiology and Biotechnology
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• v.16 no.10
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• pp.1646-1649
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• 2006

Protein synthesis is the ultimate outcome of gene expression which, in turn, is regulated by several translation factors. We attempted to identify substances that can inhibit the translation process in vitro when the outcome protein is luciferase. To this end, we developed a sensitive cell-free protein synthesis assay using luciferase as the reporter. The synthesis of luciferase increased proportionately as mRNA was added to a $15-{\mu}l$reaction medium in concentrations raging from 5 ng to 500 ng. The maximum amount of luciferase was synthesized when the media were incubated at $25^{\circ}C$ for 40 min. The concentration of each compound that inhibited luciferase production by 50% ($IC_{50}$) was calculated. Hygromycin, puromycin, and cycloheximide yielded an $IC_{50}$ of 0.008, 0.8, and $0.7{\mu}g/ml$, respectively. A filtrate of Streptomyces spp. isolates inhibited protein synthesis up to S-fold when added to the in vitro translation assay mixture.