• Journal of Photoscience
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• v.9 no.2
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• pp.94-97
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• 2002

Light is one of the most important environmental factors that influence plant growth and development. It does not function independently but exerts its role through coordinated interactions with intrinsic developmental programs, such as hormonal regulation. One typical example is hypocotyl growth in which light signals are modulated through growth hormones. However, the underlying molecular mechanisms are largely unknown. We demonstrated that brassinosteroids play an important role in the light signal transduction in etiolated hypocotyl growth. A light-responsive Ras-like G-protein, Pra2 from pea, physically and functionally interacts with a cytochrome P450 that specifically catalyzes C-2 hydroxylation in brassinosteroid biosynthesis. The cytochrome P450 expression, along with Pra2, is induced in the dark and predominantly localized in the rapidly elongating zone of etiolated pea epicotyls. Transgenic plants with a reduced level of Pra2 exhibit a dark-specific dwarfism, which is completely rescued by brassinosteroid application. On the contrary, overexpression of the cytochrome P450 results in enhanced hypocotyl growth even in the light, which phenocopies the etiolated hypocotyl growth. It is therefore envisioned that Pra2 is a molecular switch that mediates the crosstalk between light and brassinosteroids in the etiolation process.

• BMB Reports
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• v.44 no.10
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• pp.613-618
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• 2011

Two key molecules in skeletal tissues are bone formation master transcription factor Runx2 and the steroid hormone estrogen. It is well known that these two molecules play pivotal roles in bone homeostasis; however, the functional interaction between Runx2 and estrogen synthesis in skeletal tissues is largely unknown. Recent studies have indicated that there is a positive relationship between Runx2 and the estrogen biosynthesis pathway. In this review, a possible functional link between Runx2 and estrogen synthesis pathway in skeletal tissues will be discusses as well as the biological significance of this interaction.

• Journal of Nutrition and Health
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• v.33 no.4
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• pp.395-402
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• 2000

This study was carried out to explore the hypocholesterolemic effect of dehyulled defatty soy flour and its possible mechanisms including endocrine status, cholesterol biosynthesis, and fecal excretion in rats. Animals fed casein were used as control and each phospholipid compared with casein feeding. Cholesterol concentrations in all lipoprotein fraction were significantly lower in defatted soy flour group compared with casein-fed control. Defatted soy flour feeding also significantly lowered hepatic total lipid, cholesteol and TG, and increaed fecal bile acid excretion by 270% compared with casein feeding. Defattd soy flour feeding had no significant effect on plasma thyroid hormone levels and hepatic 3-hydroxy-3-methyl glutary coenzyme A(HMG-CoA) reductase activity. However, plasma T4 concentration was slightly elevated and HMG-CoA reductase activity was suppressed in defatted soy flour group. These metabolic alterations partially explain the reduced plasma and hepatic cholesterol levels of rats fed defatted soy flour.

• Reproductive and Developmental Biology
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• v.34 no.2
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• pp.111-115
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• 2010

Erythropoietin (EPO), a glycoprotein hormone produced from primarily cells of the peritubular capillary endothelium of the kidney, is responsible for the regulation of red blood cell production. We have been investigating the roles of glycosylation site added in the biosynthesis and function of recombinant protein. In this study, we analyzed by immunohistochemical methods adaptive mechanisms to excessive erythrocytosis in transgenic (tg) mice expressing dimeric human erythropoietin (dHuEPO) gene. Splenomegaly was observed over 11~21 times in the tg mice. The 2,672 candidate spleen-derived genes were identified through the microarray analysis method, and decreased genes were higher than increased genes in the spleen. The specific proteins in the increased and decreased genes were analyzed by immunohistochemical methods. Our results demonstrate that problems of abnormal splenomegaly would solve in tg mice overexpressing dHuEPO gene.

• Journal of Dairy Science and Biotechnology
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• v.36 no.1
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• pp.26-31
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• 2018

Tarak is a traditional Korean fermented milk product, which is prepared by the addition of rice wine to milk. The major microbial strains found in Tarak are Leuconostoc citreum, Lactobacillus plantarum, Lactococcus lactis, Saccharomyces cerevisiae, and Pichia kudriavzevii. The activity of lactic acid bacteria isolated from traditional Korean foods of Taraki against the carcinogenic bacteria Helicobacter pylori, Escherichia coli O157:H7, and Cronobacter sakazakii was characterized. Tarak extract significantly increased the proliferation of T-lymphocyte Jurkat (clone E6-1) cells. Tarak also inhibited the tyrosinase activity and melanin biosynthesis induced by an ${\alpha}$-melanocyte-stimulating hormone in pituitary intermediate lobe.

• Applied Biological Chemistry
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• v.19 no.2
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• pp.70-74
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• 1976

In order to study the mechanism of biosynthesis of thyroid hormones, radioactive iodine was injected into the rats and thyroid glands were removed. Iodine compounds hydrolyzed by pancreatin viokase were separated by paper chromatography and analyzed by radioautography. Radioautograms showed that the uptake of iodine starts immediately and forms diiodotyrosine through monoiodotyrosine. Evidence supported the possibility that diiodotyrosine is a precursor of thyrosine and triiodothyronine is a degradation product of thyroxine. The rat administered propylthiouracil showed inorganic iodine concentration activity, while the binding activity was prevented.

• Journal of Life Science
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• v.13 no.3
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• pp.248-251
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• 2003

The kinetics of dimerization of a newly synthesized thyroglobulin (Tg), the precursor protein in the manufacture of thyroid hormone, was investigated in the endoplasmic reticulum of thyrocytes FRTL-5 cell line. The folded monomeric Tg was first detectable in a conformationally unstable form, from the examination of lysates of pulse labeled cultured thyrocytes by denaturing and nondenaturing gel electrophoresis by 15 min after biosynthesis. The first dimeric Tg was formed by 30 min after; the monomer declined and the dimer progressively increased, and 40 min after remarkable dimeric Tg form was found. Finally, dimerization was complete at 60 min after.

• The Korean Journal of Pharmacology
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• v.30 no.1
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• pp.19-28
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• 1994

The effects of gonadoropin-releasing hormone (GnRH) and ovarian steroid hormones on the release of luteinizing hormone (LH) and its subunit mRNA levels were investigated in anterior pituitary cells in culture. LH concentration was measured by a specific radioimmunoassay and mRNA levels of u and $LH{\beta}$ subunits by RNA slot blot hybridization assay. GnRH stimulated LH release in a dose-dependent manner from cultured pituitary cells. However, the basal LH release in the absence of GnRH was not changed during the course of 24h culture, strongly suggesting that release of LH is directly controlled by GnRH. The treatment of the pituitary cells with GnRH increased $LH{\beta}$ subunit mRNA levels in a dose-dependent manner, reaching the maximum with $2\;{\times}\;10^{-10}M$ GnRH while no significant increase in ${\alpha}$ subunit mRNA levels was observed after GnRH treatment. Estradiol did not augment GnRH-induced LH release while progesterone augmented GnRH-induced LH release in a dose-dependent manner at the level of pituitary. However, estradiol and progesterone increased basal and GnRH-induced $LH{\beta}$ subunit mRNA levels in a dose-dependent manner. The treatment of estrogen antagonist, LYI17018 blocked the effect of estradiol on GnRH-induced $LH{\beta}$ subunit mRNA levels in a dose-dependent manner while progesterone antagonist, Ru486 tended to block the effect of progesterone on GnRH-induced $LH{\beta}$ subunit mRNA levels. It is therefore suggested that GnRH Playa a major role in LH release and subunit biosynthesis by influencing the steady state $LH{\beta}$ subunit mRNA loves and ovarian steroid hormones modulate subunit biosynthesis via directly acting on pituitary gonadotropes.

• Environmental Mutagens and Carcinogens
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• v.26 no.2
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• pp.53-58
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• 2006

Normally, environmental toxicants are classified as endocrine disruptors if they interfere with regulation of cellular function by endogeneous steroids through inhibition of receptor binding and/or transcriptional activation. So, many studies have been performed about agonist/antagonist of hormone receptor to study mechanisms of endocrine disruptors. If toxicants affect steroid biosynthesis and/or degradation and alter hormone homeostasis, these also are classified as endocrine disruptors. But there are not many studies of the mechanisms of endocrine disruptors on the basis of alteration of steroid biosynthesis and/or degradation. Isolation and culture of Leydig cells from testis is one of methods for the steroidogenesis screening assays to evaluate a substance for altering steroidogenesis. Leydig cells were harvested using the method described by Klinefelter with modifications. Leydig cells were purified by perfusion of testis and incubation ($34^{\circ}C$, 80cycles/minute, 20 minutes) with collagenase (0.25 mg/kg), centrifugal elutriation, percoll gradient centrifugation and BSA multidensity gradient centrifugation. To confirm if this method is one of appropriate tools to evaluate a substance for altering steroidogenesis, ketoconazole, positive control was administered to purified Leydig cells. Ketoconazole ($10^{-8}M$ and above) significantly reduced testosterone production in purified Leydig cells. From above results, we suggest that this method for steroidogenesis screening assay appears to be a appropriate tool to detect suspected compounds for altering steroidogenesis.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.1
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• pp.50-53
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• 2007

To develope skin-whitening or therapeutic agents against hyperpigmentation, aqueous extract from Amomum xanthioides (AEAX) was evaluated for melanogenesis inhibitory activity in B16F10 melanoma cell. The treatment with AEAX at the 0.5 and 1.0 mg/ml level significantly inhibits the biosynthesis of melanin compared with untreated control. The AEAX-treated cells at the 1.0 mg/ml level were more efficient than commercial arbutin at 0.1 mg/ml. The tyrosinase activity also significantly decreased in AEAX-treated cells at the 0.5 and 1.0 mg/ml level. The Western analyses confirmed the significantly decreased expression of tyrosinase and tyrosinase-related protein-1 by AEAX treatment. These results indicate that AEAX may contribute to the inhibition of melanin biosynthesis through regulating tyrosinase activity and expression and serve as a new candidate in the design of new skin-whitening or therapeutic agents.