• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.96-97
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• 2000

• Biomolecules & Therapeutics
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• v.25 no.1
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• pp.26-43
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• 2017

Endocytosis is a process by which cells absorb extracellular materials via the inward budding of vesicles formed from the plasma membrane. Receptor-mediated endocytosis is a highly selective process where receptors with specific binding sites for extracellular molecules internalize via vesicles. G protein-coupled receptors (GPCRs) are the largest single family of plasma-membrane receptors with more than 1000 family members. But the molecular mechanisms involved in the regulation of GPCRs are believed to be highly conserved. For example, receptor phosphorylation in collaboration with ${\beta}$-arrestins plays major roles in desensitization and endocytosis of most GPCRs. Nevertheless, a number of subsequent studies showed that GPCR regulation, such as that by endocytosis, occurs through various pathways with a multitude of cellular components and processes. This review focused on i) functional interactions between homologous and heterologous pathways, ii) methodologies applied for determining receptor endocytosis, iii) experimental tools to determine specific endocytic routes, iv) roles of small guanosine triphosphate-binding proteins in GPCR endocytosis, and v) role of post-translational modification of the receptors in endocytosis.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.77.2-77.2
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• 2003

The dopamine D2 receptor (D$_2$R) is target for antipsychotic drugs and associated with several neuropsychiatric disorders. The internalization (sequestration) of G protin-coupled receptor is caused by agonist-induced receptor phosphorylation mediated by GRK, followed by the interaction with ${\beta}$-arrestin. In this study, we examined the agonist-dependent sequestration/internalization of dopamine D$_2$R, which were transiently expressed in HEK 293 cells with of without GRK co-expression. Co-expression of GRK2 or GRK3 markedly enhanced the sequestration of D$_2$R. (omitted)

• Journal of the East Asian Society of Dietary Life
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• v.15 no.3
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• pp.315-322
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• 2005

In this study we report on the estrogen activity of silkworm pupa and herb extracts in vitro. The estrogenic activity of these resources was investigated by competition binding assays with estrogen receptor $\alpha(ER{\alpha})\;or\;ER{\beta}$, and viability of MCF-7 cells, a human breast cancer cell line. Saturation ligand-binding analysis of $ER{\alpha}\;and\;ER{\beta}$ revealed that all plant extracts competed with estrogen ligand for binding to both ER subtypes with a similar preference and degree and competed stronger with ligand for binding to $ER{\beta}\;than\;to\;ER{\alpha}$. The highest $ER{\alpha}-binding$ sample was silkworm pupa aqueous extract The highest $ER{\beta}-binding$ sample was silkworm pupa oil. These samples were further tested for bioactivity based on their ability to regulate cell growth rate in ER(+) breast cancer cell line, MCF-7 cells. Our studies showed that silkworm pupa, soritae, sesame, yam, pueraria, malt, ginseng, Polygonum multiflorum, and Curcuma longa significantly stimulated the growth of MCF-7 cells (P<0.05). In summary, these results suggested that silkworm pupa and herbs might be useful as potential phytoestrogens.

• Journal of Korean Biological Nursing Science
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• v.10 no.1
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• pp.80-87
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• 2008

Purpose: Hypoestrogenism caused by ovariectomy, disease, or menopause is associated with increased obesity in women. Altered fat distribution and weight gain are consequences of menopausal hypoestrogenism, but the mechanisms responsible are not completely known. This study examined the effect of estrogen on obesity in ovariectomized rats. Method: The groups of female rats were 4 weeks post ovariectomy (OVX) or, 4 weeks post-sham operation (SHAM), and 2 weeks post ovariectomy followed by 2 weeks replacement with estradiol benzoate (ER-$16{\mu}g$/kg, subq, qd). Serum ghrelin level was measured by radioimmunoassay (RIA). The expression of adrenergic receptors in adipose tissue was measured by Western blotting assay. Result: OVX significantly increased body weight, serum cholesterol. Two weeks estrogen replacement reduced body weight accompanied by the increment of serum ghrelin and the reduction of the receptor ratio of adrenergic ${\alpha}_{2A}/{\beta}_1$, and ${\alpha}_{2A}/{\beta}_3$. Conclusion: We provide evidence that estrogen reduces obesity through the altered receptor ratio of adrenergic ${\alpha}_{2A}/{\beta}_1$, and ${\alpha}_{2A}/{\beta}_3$ in adipose tissue in ovariectomized rats.

• Journal of Integrative Natural Science
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• v.7 no.1
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• pp.25-38
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• 2014

Amyloid-${\beta}$-peptide ($A{\beta}$) is important in the pathogenesis of Alzheimer's disease (AD). Calpain ($Ca^{2+}$-dependent protease) and caspase-8 (the initiating caspase for the extrinsic, receptor-mediated apoptosis pathway) have been implicated in $AD/A{\beta}$ toxicity. We found that $A{\beta}$ promoted degradation of calpastatin (the specific endogenous calpain inhibitor); calpastatin degradation was prevented by inhibitors of either calpain or caspase-8. The results implied a cross-talk between the two proteases and suggested that one protease was responsible for the activity of the other one. In neuron-like differentiated PC12 cells, calpain promotes active caspase-8 formation from procaspase-8 via the $A{\beta}$ and CD95 pathways, along with degradation of the procaspase-8 processing inhibitor caspase-8 (FLICE)-like inhibitory protein, short isoform (FLIPS). Inhibition of calpain (by pharmacological inhibitors and by overexpression of calpastatin) prevents the cleavage of procaspase-8 to mature, active caspase-8, and inhibits FLIPS degradation in the $A{\beta}$-treated and CD95-triggered cells. Increased cellular Ca2+ per se results in calpain activation but does not lead to caspase-8 activation or FLIPS degradation. The results suggest that procaspase-8 and FLIPS association with cell membrane receptor complexes is required for calpain-induced caspase-8 activation. The results presented here add to the understanding of the roles of calpain, caspase- 8, and CD95 pathway in $AD/A{\beta}$ toxicity. Calpain-promoted activation of caspase-8 may have implications for other types of CD95-induced cell damage, and for nonapoptotic functions of caspase-8. Inhibition of calpain may be useful for modulating certain caspase-8-dependent processes.

• Nutritional Sciences
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• v.6 no.4
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• pp.239-245
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• 2003

The $\beta$3-adrenergic receptor ($\beta$3AR) plays a major role in thermogenesis and lipolysis in brown and visceral adipose tissue, and has been implicated in the pathogenesis of obesity and metabolic disorders. The purpose of this study was to estimate the effects of $\beta$3AR gene polymorphism on the risk of hyperglycemia in 980 Korean women who attended a weight loss program in a local clinic. Each subject s height, weight, BMI, WHR, obesity index and body composition were measured. The genotype of the $\beta$3AR gene in codon 64 was analyzed by the PCR RFLP method. Serum concentrations of fasting glucose, of total and HDL cholesterol, and of TG were determined. Genotype distributions were as follows : 67% WW type, 31% WR type, and 2% RR type. Among the many measured parameters, fasting glucose levels were significantly higher in the WR/RR type compared with the WW type (p=0.0ll). When the subjects were divided into two groups by a fasting blood glucose level higher or lower than 6.105mmol/L (110mg/dl), the frequency of hyperglycemia showed a significant difference in relation to $\beta$3AR genotype as measured by $\X^2$-analysis (p=0.014); the frequency of hyperglycemia was significantly higher (at 24.8%) in WR/RR type subjects, compared to 18.2% in WW type subjects. When all of the measured parameters were included in stepwise logistic regression analyses to find the risk factors for hyperglycemia, the odds ratios for hyperglycemia were 1.573 (p=0.0ll) for the WR/RR type of the $\beta$3AR gene, 1.053 (p=0.001) for TG, 1.044 (p=0.037) for BMI, and 1.026 for age (p=0.031). These data suggest that the WR/RR genotype of the $\beta$3AR has a very strong association with increased blood glucose level and might be a significant risk factor for hyperglycemia among Korean women.

• Biomedical Science Letters
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• v.13 no.2
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• pp.119-125
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• 2007

It is widely known that protein tyrosine kinases (PTKs) are involved in controlling many biological processes such as cell growth, differentiation, proliferation, survival and apoptosis. An $\alpha3\beta4$ subunit combination acts as a major functional acetylcholine receptor (nAChRs) in male rat major pelvic ganglion (MPG) neurons, and their activation induces fast inward currents and intracellular calcium increases. Recently it has been reported that the activity of acetylcholine receptors (AChRs) in some neurons can be negatively regulated by PTKs. However, the exact mechanism of regulation of nAChRs by PTKs is poorly understood. Therefore, we examined the potential role particular in nAChR by PTK using electrophysiology and calcium imaging in male rat MPG neurons. ACh induced inward currents and $(Ca^{2+})_i$ increases in MPG neurons, concomitantly. These responses were inhibited by more than 90% in $Na^+$- or $Ca^{2+}$- free solution. $\alpha$-conotoxin AuIB, a selective $\alpha3\beta4$ nAChR blocket, inhibited ACh-induced inward currents. Genistein (10 $\mu$M), a broad-spectrum tyrosine kinase inhibitor, markedly decreased ACh-induced currents and $Ca^{2+}$ transients, whereas 10 $\mu$M genistin, an inactive analogue, had little effect. Overall these data suggest that the activities of $\alpha3\beta4$ AChRs in MPG neurons are positively regulated by PTK. In conclusion, trosine kinase may be one of the key factors in the regulation of $\alpha3\beta4$ nAChRs in rat MPG neurons, which may play an important roles in the autonomic neuronal function such as synaptic transmission, autonomic reflex, and neuronal plasticity.

• The Korean Journal of Pharmacology
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• v.28 no.1
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• pp.75-79
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• 1992

Higenamine, which is one of active component of Aconiti tuber, has been known to have positive inotropic effect through adrenergic beta-receptor. The effect of higenamine on norepinepharine or potassium induced contraction of pulmonary aorta in rabbit were studies. 1. The contraction of aortic strips induced by norepinephrine was suppressec by pre-or post-treatment of higenamine dose dependently and those effects of higenamine were prevented by propranolol. The $pA_2$ value of higenamine against propranolol calculated as 8.25. 2. The effect of higenamine was not affected by phentolamine. 3. Isoprotrenol has shown 10 times stronger vasodiatory effect on norepinephrine induced cntracture than that of higenamine but high concentration $(3.3{\times}10^{-6}\;M)$ of isoproterenol produce intrinsic activity. 4. Vasodilatory effect of higenamine or isoproterenol was not observed in potassium induced contacture of pulmonary aortic strips. These results strongly suggest that higenamine dilated the pulmonary vascular smooth muscle through stimulation of adrenergic beta-receptor.

• The Korean Journal of Food And Nutrition
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• v.12 no.2
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• pp.184-190
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• 1999

Soybean protein consists of two major components $\beta$-conglycinin and glycinin which together consti-tute 70% of the total seed storage protein at maturity. $\beta$-Conglycinin is trimeric glycoprotein and for-med by the assembly of various combinations of three subunits $\alpha$,$\alpha$' and $\beta$ which have molecular weig-hts of 69,000, 72,000 and 42,000, respectively. Recently $\beta$-conglycinin was identified as powerful LDL lip-oprotein receptor activation hypercholesterolemia and major allergenic proteins. To investigate these reasons we constructed an expression system of cDNA encoding $\alpha$-subunit of $\beta$-conglycinin in Escherichia coli and purified the expressed protein. The pro-$\beta$-conglycinin synthesized in Escherichia coli BL 21 (DE3)comprised approximately 15% of the total bacterial proteins and the expressed protein are formed sol-uble and trimer such as native protein in Escherichia coli cells. The highly expressed protein was purified to homogeneity by salt precipitation with 20~40 % ammonium sulfate ion-exchange chromatography with Q-sepharose and hydrophobic column chromatography with Butyltoyopearl.