• 한국식품과학회지
• /
• 제51권3호
• /
• pp.272-277
• /
• 2019

본 연구진은 선행연구에서 MCE-DAG를 섭취한 마우스에서 혈중 총 콜레스테롤과 LDL 콜레스테롤의 감소를 보고한 바 있어, 본 연구에서 in vitro를 통해 MCE-DAG와 간의 콜레스테롤 항상성 기전의 관련성을 구명하고자 하였다. LDLR과 같은 콜레스테롤 흡수 관련 인자의 발현이 MCE-DAG에 의해 증가한 반면, LDLR을 억제하는 PCSK9의 발현은 감소하였다. 또한, 콜레스테롤 합성 관련 인자인 HMGCR의 발현이 MCE-DAG에 의해 증가하였고, 전사조절인자인 SREBP2의 발현이 증가하였다. 이러한 결과들은 콜레스테롤의 합성과 흡수가 동시에 증가하였음을 뒷받침한다. 즉, 간 내 콜레스테롤 필요량이 증가함에 따라, 간의 콜레스테롤 합성 및 흡수를 활성화시켜 콜레스테롤 항상성을 유지하는 기전이 촉진되었음을 의미한다. 하지만 간 세포 내 총 콜레스테롤 양은 MCE-DAG에서 영향을 받지 않았다. 콜레스테롤 흡수 및 합성 기전이 촉진되었음에도 세포 내 콜레스테롤 농도가 증가하지 않은 현상은 담즙산 등 콜레스테롤 분비 촉진에 의한 것일 수 있다. 이러한 추론은 추후 콜레스테롤 분비 기전을 검증할 수 있는 실험을 설계하여 검증해볼 필요성이 있다. 결론적으로 MCE-DAG는 세포 내 콜레스테롤 흡수 작용을 촉진하는 효과가 있어 추후 기능성 유지로 활용 가능할 것으로 판단된다.

• Nutrition Research and Practice
• /
• 제14권2호
• /
• pp.95-101
• /
• 2020

BACKGROUND/OBJECTIVES: Folate plays a critical role in DNA synthesis and methylation. Intracellular folate homeostasis is maintained by the enzymes folylpolyglutamate synthase (FPGS) and γ-glutamyl hydrolase (GGH). FPGS adds glutamate residues to folate upon its entry into the cell through a process known as polyglutamylation to enhance folate retention in the cell and to maintain a steady supply of utilizable folate derivatives for folate-dependent enzyme reactions. Thereafter, GGH catalyzes the hydrolysis of polyglutamylated folate into monoglutamylated folate, which can subsequently be exported from the cell. The objective of this review is to summarize the scientific evidence available on the effects of intracellular folate homeostasis-associated enzymes on cancer chemotherapy. METHODS: This review discusses the effects of FPGS and GGH on chemosensitivity to cancer chemotherapeutic agents such as antifolates, such as methotrexate, and 5-fluorouracil. RESULTS AND DISCUSSION: Polyglutamylated (anti)folates are better substrates for intracellular folate-dependent enzymes and retained for longer within cells. In addition to polyglutamylation of (anti)folates, FPGS and GGH modulate intracellular folate concentrations, which are an important determinant of chemosensitivity of cancer cells toward chemotherapeutic agents. Therefore, FPGS and GGH affect chemosensitivity to antifolates and 5-fluorouracil by altering intracellular retention status of antifolates and folate cofactors such as 5,10-methylenetetrahydrofolate, subsequently influencing the cytotoxic effects of 5-fluorouracil, respectively. Generally, high FPGS and/or low GGH activity is associated with increased chemosensitivity of cancer cells to methotrexate and 5-fluorouracil, while low FPGS and/or high GGH activity seems to correspond to resistance to these drugs. Further preclinical and clinical studies elucidating the pharmocogenetic ramifications of these enzyme-induced changes are warranted to provide a framework for developing rational, effective, safe, and customized chemotherapeutic practices.

• 대한화장품학회:학술대회논문집
• /
• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book II
• /
• pp.73-86
• /
• 2003

Endothelins secreted from keratinocytes are intrinsic madiators for human melanocytes in UVB-induced pigmentation. Antimelanogenic ingredient, 1,2-Ο-diferulylglycerol(SM709) isolated from bamboo extract inhibited the melanin synthesis of Bl6F10 melanoma cells by 62%. To understand the cellular mechanism of antimelanogenic activity of SM709 in human melanocytes, the effects of SM709 on the ET-l-induced $Ca^{2+}$ mobilization were investigated. ET-l receptors in human melanocytes were characterized by using specific antagonist and found that ET-l increased intracellular $Ca^{2+}$ by activating ET-B receptor. SM709 completely blocked the ET-l-induced intracellular $Ca^{2+}$ increase and its inhibitory effect showed dose- and time- dependent manners. To investigate the role of SM709 on intracellular $Ca^{2+}$ store, when the $Ca^{2+}$ store was partially depleted by thapsigargin; a specific inhibitor of ER-type $Ca^{2+}$-ATPase, caffeine-induced $Ca^{2+}$ mobilization did not changed in the presence or absence of SM709, suggesting that SM709 has no effect on the $Ca^{2+}$ store. It is known that LPA receptor and P$_2$ receptor are linked to InsP$_3$ second messenger system. When these receptors in melanocytes were activated by LPA and ATP, the intracellular $Ca^{2+}$ signaling was observed even in the presence of SM709. From the above results, it can be suggested that SM709 has an antimelanogenic activity by antagonizing the ET-B receptor, resulting in subsequent intracellular $Ca^{2+}$ signaling, in UV induced pigmentation.nduced pigmentation.

• Toxicological Research
• /
• 제9권1호
• /
• pp.45-60
• /
• 1993

The present study was carried out to evaluate the cytotoxicity of cadmium on cultured rat fibroblasts. The colorimetric assays of neutral red and tetrazolium MTT, the lactatedehydrogenase activity, the amounts of total protein, the rate of DNA synthesis, the amounts of unscheduled DNA synthesis, the frequency of sister chromatid exchange, the releasing rate of intracellular calcium, and light and electron microscopic studies were performed on cultured rat fibroblasts maintained in the media containing various concentrations of cadmium. The results were as follows: The neutral red(NR) and MTT values were decreased dose-dependently by cadmium, and the NR90, NR50, MTT90 and MTT50 values of cadmium were 0.2mM, 21.5mM, 1.0Mm and 60.0Mm, respectively.

• 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.

• Journal of Microbiology and Biotechnology
• /
• 제31권1호
• /
• pp.154-162
• /
• 2021

L-5-methyltetrahydrofolate (5-MTHF) is one of the biological active forms of folate, which is widely used as a nutraceutical. However, low yield and serious pollution associated with the chemical synthesis of 5-MTHF hampers its sustainable supply. In this study, 5-MTHF production was improved by engineering the 5-MTHF biosynthesis pathway and NADPH supply in Lactococcus lactis for developing a green and sustainable biosynthesis approach. Specifically, overexpressing the key rate-limiting enzyme methylenetetrahydrofolate reductase led to intracellular 5-MTHF accumulation, reaching 18 ㎍/l. Next, 5-MTHF synthesis was further enhanced by combinatorial overexpression of 5-MTHF synthesis pathway enzymes with methylenetetrahydrofolate reductase, resulting in 1.7-fold enhancement. The folate supply pathway was strengthened by expressing folE encoding GTP cyclohydrolase I, which increased 5-MTHF production 2.4-fold to 72 ㎍/l. Furthermore, glucose-6-phosphate dehydrogenase was overexpressed to improve the redox cofactor NADPH supply for 5-MTHF biosynthesis, which led to a 60% increase in intracellular NADPH and a 35% increase in 5-MTHF production (97 ㎍/l). To reduce formation of the by-product 5-formyltetrahydrofolate, overexpression of 5-formyltetrahydrofolate cyclo-ligase converted 5-formyltetrahydrofolate to 5,10-methyltetrahydrofolate, which enhanced the 5-MTHF titer to 132 ㎍/l. Finally, combinatorial addition of folate precursors to the fermentation medium boosted 5-MTHF production, reaching 300 ㎍/l. To the best of our knowledge, this titer is the highest achieved by L. lactis. This study lays the foundation for further engineering of L. lactis for efficient 5-MTHF biosynthesis.

• Korean Chemical Engineering Research
• /
• 제60권3호
• /
• pp.392-397
• /
• 2022

Methane is one of the major greenhouse gases, recently, the biotechnological conversion from methane to high-value added chemicals have emerged as an effort to reduce methane gas emission. In this study, we optimized ectoine bio-milking conditions in which cells were repeatedly used to improve intracellular and extracellular ectoine yield from methane by using Methylomicrobium alcaliphilum 20ZDP2. First, the cultivation and intracellular ectoine accumulation conditions were optimized with respect to the growth phase and medium salinity to achieve the highest yield of synthesis. Second, ectoine excretion was optimized by determining the ectoine secretion time (15 min) in appropriate medium salinity under hypoosmotic conditions (1% NaCl). Finally, bio-milking of ectoine was successfully repeated more than 10 times using M. alcaliphilum 20ZDP2, and the ectoine yield was improved up to 129.29 mg/ DCW g.

• Archives of Pharmacal Research
• /
• 제12권3호
• /
• pp.207-213
• /
• 1989

This study was performed to investigate the mechanism of in vitro cytotosic actions of polyacetylenes which are panaxydol, panaxynol and panaxytriol isolated from Panax ginseng C. A. Meyer. DNA synthesis of L1210 cells was significantly inhibited with dose dependent pattern when L1210 cells were treated for 1 hour with over 5 .mu.g/ml of polyacetylenes. Panaxydol which had the most potent cytotoxicity among three polyacetylenes showed also the strongest inhibitory effect on DNA synthesis. Intracellular cyclic AMP levels of L1210 cells treated with 2.5 $\mu$g/ml of panaxydol or panaxytriol were significantly elevated on the incubation duration. The elevation of cyclic AMP levels by panaxytriol was higher than that by panaxydol, but no significant increase in cyclic AMP by panaxynol was observed. All three polyacetylenes had no effect on glycolysis of L1210 cells. Electron microscopic observations revealed that polyacetylenes caused damage to plasma membranes of L1210 cells in proportion to their cytotoxicities at each $ED_{50}$ value (panaxydol > panaxynol> panaxytriol). These results suggest that cytotoxicities of polyacetylenes against L1210 cells might be mediated by elevated cyclic AMP level, even though the relationship among their cytotoxicities, inhibitory effect on DNA synthesis and ability to elevation of cyclic AMP level are not fully agreed, and might be also related to membrane damage.

• BMB Reports
• /
• 제56권7호
• /
• pp.385-391
• /
• 2023

Aspartate-glutamate carrier 2 (AGC2, citrin) is a mitochondrial carrier expressed in the liver that transports aspartate from mitochondria into the cytosol in exchange for glutamate. The AGC2 is the main component of the malate-aspartate shuttle (MAS) that ensures indirect transport of NADH produced in the cytosol during glycolysis, lactate oxidation to pyruvate, and ethanol oxidation to acetaldehyde into mitochondria. Through MAS, AGC2 is necessary to maintain intracellular redox balance, mitochondrial respiration, and ATP synthesis. Through elevated cytosolic Ca²⁺ level, the AGC2 is stimulated by catecholamines and glucagon during starvation, exercise, and muscle wasting disorders. In these conditions, AGC2 increases aspartate input to the urea cycle, where aspartate is a source of one of two nitrogen atoms in the urea molecule (the other is ammonia), and a substrate for the synthesis of fumarate that is gradually converted to oxaloacetate, the starting substrate for gluconeogenesis. Furthermore, aspartate is a substrate for the synthesis of asparagine, nucleotides, and proteins. It is concluded that AGC2 plays a fundamental role in the compartmentalization of aspartate and glutamate metabolism and linkage of the reactions of MAS, glycolysis, gluconeogenesis, amino acid catabolism, urea cycle, protein synthesis, and cell proliferation. Targeting of AGC genes may represent a new therapeutic strategy to fight cancer.

• Journal of Veterinary Science
• /
• 제23권1호
• /
• pp.8.1-8.15
• /
• 2022

Background: Brucella infection induces brucellosis, a zoonotic disease. The intracellular circulation process and virulence of Brucella mainly depend on its type IV secretion system (T4SS) expressing secretory effectors. Secreted protein BspJ is a nucleomodulin of Brucella that invades the host cell nucleus. BspJ mediates host energy synthesis and apoptosis through interaction with proteins. However, the mechanism of BspJ as it affects the intracellular survival of Brucella remains to be clarified. Objectives: To verify the functions of nucleomodulin BspJ in Brucella's intracellular infection cycles. Methods: Constructed Brucella abortus BspJ gene deletion strain (B. abortus ∆BspJ) and complement strain (B. abortus pBspJ) and studied their roles in the proliferation of Brucella both in vivo and in vitro. Results: BspJ gene deletion reduced the survival and intracellular proliferation of Brucella at the replicating Brucella-containing vacuoles (rBCV) stage. Compared with the parent strain, the colonization ability of the bacteria in mice was significantly reduced, causing less inflammatory infiltration and pathological damage. We also found that the knockout of BspJ altered the secretion of cytokines (interleukin [IL]-6, IL-1β, IL-10, tumor necrosis factor-α, interferon-γ) in host cells and in mice to affect the intracellular survival of Brucella. Conclusions: BspJ is extremely important for the circulatory proliferation of Brucella in the host, and it may be involved in a previously unknown mechanism of Brucella's intracellular survival.