• 한국동물학회지
• /
• 제35권3호
• /
• pp.271-276
• /
• 1992

20-hydroxvecdysone (20-HE) seems to be related in the regulation of vitellogenesis in Drosophifa sp. (robwta species sroup). Although yolk proteins (YPs) synthesis does not occur at a high rate in fat body cells of one daw-old female after eclosion, application of 20-HE to isolated abdomens deprived of anterior endocrine glands stimulated the synthesis and secretion of YPs into the hemolvmph. An injection of 0.3 $\mul$ of a 10-s M 20-HE was sufficient topromote synthesis and secretion of YPs in isolated abdomens. The response of isolated automens to hormones was first detected between 2 hr and 3 hr after treaDent of 10-s M 20-HE. Transcript analysis showed that the effect of 20-HE on yolk protein synthesis was mediated at the level of transcription.

• 한국자기공명학회논문지
• /
• 제2권2호
• /
• pp.152-157
• /
• 1998

The diversity of RNA functions ranges from storage and propagation of genetic information to enzymatic activity during RNA processing and protein synthesis. This diversity of functions requires an equally diverse arrays of structures, and, very often, the formation of functional RNA-protein complexes. Recognition of specific RNA signals by RNA-binding proteins is central to all aspects of post-transcriptional regulation of gene expression. We will describe how NMR is being used to understand at the atomic level how these important biological processes occur.

• Nutrition Research and Practice
• /
• 제3권1호
• /
• pp.64-71
• /
• 2009

Amino acids are fundamental nutrients for protein synthesis and cell growth (increase in cell size). Recently, many compelling evidences have shown that the level of amino acids is sensed by extra- or intra-cellular amino acids sensor(s) and regulates protein synthesis/degradation. Mammalian target of rapamycin complex 1 (mTORC1) is placed in a central position in cell growth regulation and dysregulation of mTOR signaling pathway has been implicated in many serious human diseases including cancer, diabetes, and tissue hypertrophy. Although amino acids are the most potent activator of mTORC1, how amino acids activate mTOR signaling pathway is still largely unknown. This is partly because of the diversity of amino acids themselves including structure and metabolism. In this review, current proposed amino acid sensing mechanisms to regulate mTORC1 and the evidences pro/against the proposed models are discussed.

• BMB Reports
• /
• 제33권2호
• /
• pp.103-111
• /
• 2000

Phosphorylation of the eukaryotic elongation factor 2 (eEF-2) blocks the elongation step of translation and stops overall protein synthesis. Although the overall rate of protein synthesis in mitosis reduces to 20% of that in S phase, it is unclear how the protein translation procedure is regulated during the cell cycle, especially in the stage of peptide elongation. To delineate the regulation of the elongation step through eEF-2 function, the changes in phosphorylation of eEF-2, and in activity of corresponding $Ca^{2+}$/calmodulin (CaM)-dependent protein kinase III (CaMK-III) during the cell cycle of NIH 3T3 cells, were determined. The in vivo level of phosphorylated eEF-2 showed an 80% and 40% increase in the cells arrested at G1 and M, respectively. The activity of CaMK-III also changed in a similar pattern, more than a 2-fold increase when arrested at G1 and M. The activity change of the kinase during one turn of the cell cycle also demonstrated the activation at G1 and M phases. The activity change of cAMP-dependent protein kinase (PKA) was reciprocal to that of CaMK-III. These results indicated: (1) the activity of CaMK-III was cell cycle-dependent and (2) the level of eEF-2 phosphorylation followed the kinase activity change. Therefore, the elongation step of protein synthesis might be cell cycle dependently regulated.

• BMB Reports
• /
• 제30권1호
• /
• pp.55-59
• /
• 1997

The heat shock response is a universal stress response observed in all organisms and cultured cells. The response is regulated at both the transcriptional and translational level. Heat shocked Drosophila melanogaster Kc cells are used as the system for the study of translational regulation. In this system non-heat shock messages are associated with polysome but are not translated in a heat shocked condition. To figure out the change in the translation machinery. the effects of translation elongation inhibitors were tested on Kc cells. The result showed that the sensitivity of translation to these drugs changed in heat shocked cells. The significant changes were the decreased inhibition of heat shock protein synthesis by cycloheximide, emetine. and puromycin. and the increased inhibition of heat shock protein synthesis by verrucarin A. implying that the translation elongation mechanism in heat shocked cells changed.

• BMB Reports
• /
• 제48권3호
• /
• pp.139-146
• /
• 2015

Adaptive brain function and synaptic plasticity rely on dynamic regulation of local proteome. One way for the neuron to introduce new proteins to the axon terminal is to transport those from the cell body, which had long been thought as the only source of axonal proteins. Another way, which is the topic of this review, is synthesizing proteins on site by local mRNA translation. Recent evidence indicates that the axon stores a reservoir of translationally silent mRNAs and regulates their expression solely by translational control. Different stimuli to axons, such as guidance cues, growth factors, and nerve injury, promote translation of selective mRNAs, a process required for the axon's ability to respond to these cues. One of the critical questions in the field of axonal protein synthesis is how mRNA-specific local translation is regulated by extracellular cues. Here, we review current experimental techniques that can be used to answer this question. Furthermore, we discuss how new technologies can help us understand what biological processes are regulated by axonal protein synthesis in vivo.

• Preventive Nutrition and Food Science
• /
• 제22권3호
• /
• pp.172-183
• /
• 2017

Vitamin A and its metabolites modulate insulin resistance and regulate stearoyl-CoA desaturase 1 (SCD1), which are also known to affect insulin resistance. Here, we tested, whether vitamin A-mediated changes in insulin resistance markers are associated with SCD1 regulation or not. For this purpose, 30-week old male lean and glucose-intolerant obese rats of WNIN/GR-Ob strain were given either a stock or vitamin A-enriched diet, i.e. 2.6 mg or 129 mg vitamin A/kg diet, for 14 weeks. Compared to the stock diet, vitamin A-enriched diet feeding improved hyperglycemia and glucose-clearance rate in obese rats and no such changes were seen in lean rats receiving identical diets. These changes were corroborated with concomitant increase in circulatory insulin and glycogen levels of liver and muscle (whose insulin signaling pathway genes were up-regulated) in obese rats. Further, the observed increase in muscle glycogen content in these obese rats could be explained by increased levels of the active form of glycogen synthase, the key regulator of glycogen synthesis pathway, possibly inactivated through increased phosphorylation of its upstream inhibitor, glycogen synthase kinase. However, the unaltered hepatic SCD1 protein expression (despite decreased mRNA level) and increased muscle-SCD1 expression (both at gene and protein levels) suggest that vitamin A-mediated changes on glucose metabolism are not associated with SCD1 regulation. Chronic consumption of vitamin A-enriched diet improved hyperglycemia and glucose-intolerance, possibly, through the regulation of intracellular signaling and glycogen synthesis pathways of muscle and liver, but not associated with SCD1.

• 한국식품영양학회지
• /
• 제30권2호
• /
• pp.371-377
• /
• 2017

Muscle atrophy is characterized by a decrease in the mass of the muscle. With an increase in life expectancy and chronic illnesses, the incidence of muscle atrophy is increasing and the quality of life of patients is decreasing. Thus, reducing muscle atrophy is of high clinical and socio-economic importance. Mistletoe is a semi-parasitic plant that has been used as a traditional medicine in many countries to treat various human illnesses. It has been reported that Korean mistletoe extract (KME) has diverse biological functions including anti-tumor, anti-oxidant, anti-diabetic, anti-obesity properties, and extension of lifespan. Especially, we have recently reported that KME improves exercise endurance in mice, indicating its beneficial roles in enhancing the capacity of skeletal muscle. In this study, we investigated whether KME could activate the signaling pathway related to protein synthesis in a mouse model of muscle atrophy. Interestingly, KME efficiently activated the Akt/mTOR pathway, and Akt and mTOR are important signaling hub molecules for the acceleration of protein synthesis in muscle cells. In addition, KME also increased the activity of S6 kinase which is involved in the regulation of muscle cell size. Moreover, the ERK activity, required for transcription of ribosomal RNA for protein synthesis, was also enhanced in KME-treated mouse muscle. These data support the idea that KME increases muscle mass via increased protein synthesis. Our findings also suggest that Korean mistletoe might be a promising candidate for the development of functional foods that are beneficial for preventing muscle atrophy.

• 한국미생물생명공학회:학술대회논문집
• /
• 한국미생물생명공학회 2001년도 Proceedings of 2001 International Symposium
• /
• pp.165-168
• /
• 2001

Regulation of pyrimidine nucleotide synthesis has been studied extensively in enteric bacteria and Bacillus species. Varieties of control modes have been proposed for regulation of pyrimidine nucleotide biosynthetic (pyr) genes. In Bacillus caldolyticus and B. subtilis, it has been proved that pyrimidine de novo biosynthetic operon is controlled by a regulatory protein PyrR-mediated attenuation. Another Gram-positive bacteria including Enterococcus faecalis, Lactobacillus plantarum, and wctococcus lactis have been found to constitute a pyr gene cluster containing the pyrR gene. In addition, it has been proposed that the structure of the 5' leader region of the Gram-negative extreme thermophile Thermus strain Z05 pyr operon provides a novel mechanism of PyrR-dependent coupled transcription-translation attenuation. Bacterial genome sequencing projects have identified the PyrR homologues in Haemophilus influenzae, Synechocystis sp., Mycobacterium tuberculosis, Streptococcus pneumoniae, S. pyogenes, and Clostridium acetobutylicum, which are currently investigating for their physiological functions.

• Journal of Microbiology and Biotechnology
• /
• 제10권6호
• /
• pp.877-880
• /
• 2000

Cycloinulooligosaccharide fructanotransferase (CFTase) converts inulin into cyclooligosaccharides consisting of six to eight molecules $\beta$-($2\rightarrow1$)-linked cyclic D-fructofuranose through intramolecular transfructosylation. We have examined the regulation of CFTase synthesis in Bacillus macerans and Bacillus subtilis. Synthesis of the CFTase was induced by inulin and it was subject to carbon catabolite repression (CCR) by glucose in both microorganisms. The DNA sequence upstream of the promoter of the CFTase gene was not involved in the inulin induction and glucose repression of the CFTase gene expression in B. subtilis. This suggests that the DNA element(s) responsible for the inuline induction and glucose repression is located downstream of the promoter region. Unexpectedly, the CCR of the expression of CFTase gene was observed not to be dependent on CcpA protein in B. subtilis.