• Journal of Ginseng Research
• /
• v.35 no.1
• /
• pp.92-103
• /
• 2011

Ginseng has been used as a general tonic agent to invigorate human body. In the present study, we isolated novel glycolipoproteins from ginseng that activate $Ca^{2+}$-activated $Cl^-$ channel (CaCC) in Xenopus oocytes and transiently increase intracellular free $Ca^{2+}$ concentration ($[Ca^{2+}]_i$) in mouse Ehrlich ascites tumor cells. We named the active ingredients as gintonin. Gintonin exists in at least six different forms. The native molecular weight of gintonin is about 67 kDa but its apparent molecular weight is about 13 kDa, indicating that gintonin might be a pentamer. Gintonin is rich in hydrophobic amino acids. Its main carbohydrates are glucose and glucosamine. Its lipid components are linoleic, palmitic, oleic, and stearic acids. Gintonin actions were blocked by U73122, a phospholipase C inhibitor, 2-aminoethxydiphenyl borate, an inositol 1,4,5-trisphosphate receptor antagonist, or bis (o-aminophenoxy) ethane-N,N,N0,N0-tetracetic acid acetoxymethyl ester, a membrane permeable $Ca^{2+}$ chelator. In the present study, we for the first time isolated novel gintonin and showed the signaling pathways on gintonin-mediated CaCC activations and transient increase of $[Ca^{2+}]_i$. Since $[Ca^{2+}]_i$ as a second messenger plays a pivotal role in the regulation of diverse $Ca^{2+}$-dependent intracellular signal pathways, gintonin-mediated regulations of $[Ca^{2+}]_i$ might contribute to biological actions of ginseng.

• Biomolecules & Therapeutics
• /
• v.16 no.3
• /
• pp.197-202
• /
• 2008

In our previous publication we compared the gene expression profiles on hepatotoxicants exposure to assess the comparability between in vivo and in vitro test systems. We investigated global gene expression from both mouse liver and mouse hepatic cell line treated with thioacetamide (TAA) and identified several common genes. In this study, we selected genes to validate them as potential biomarkers for hepatotoxicity on the relevance of in vitro and in vivo system. Three up-regulated, aquaporin 8 (Aqp8), glutathione peroxidase 1 (Gpx1), succinate-CoA ligase, GDP-forming, alpha subunit (Suclg1) and two down-regulated, DnaJ (Hsp40) homolog subfamily C member 5 (Dnajc5) and tumor protein D52 (Tpd52) genes were tested for their effects in vitro. For characterization of gene function, short interfering RNA (siRNA) for each gene was synthesized and transfected in mouse hepatic cell line, BNL CL.2. Cell viability, mRNA expression level and morphological alterations were investigated. We confirmed siRNA transfection against selected five genes induced down-regulation of respective mRNA expression. siRNA transfection in general decreased cell viability in different degrees and induced morphological changes such as membrane thickening and alterations of intracellular structures. This suggests that these genes could be associated with TAA-induced toxicity. Furthermore, these genes may be used in the investigation of hepatotoxicity for better understanding of its mechanism.

• Environmental Mutagens and Carcinogens
• /
• v.25 no.2
• /
• pp.60-65
• /
• 2005

The human solute carrier, SLC41Al, is a $Mg^{2}+$ transporter that is regulated by extracellular magnesium. Although intracellular magnesium plays a fundamental role in cellular metabolism, little is known about how $Mg^{2}+$ is taken up and controlled by cells. Magnesium plays a fundamental role in cellular metabolism so that its control within the body is critical. Magnesium homeostasis is principally a balance between intestinal absorption of dietary magnesium and renal excretion of urinary magnesium. The kidney, mainly the distal convoluted tubule, controls magnesium reabsorption. Although renal reabsorption is under the influence of many hormones, selective regulation of magnesium transport is due to intrinsic control involving transcriptional processes and synthesis of transport proteins. Using microarray analysis, identification of the genetic elements involved with this transcriptional control has been begun. SLC41A1(GenBank Accession No. AJ514402), comprises 10 putative transmembrane domains, two of which are highly homologous to the integral membrane part of the prokaryote transports $Mg^{2}+$ and other divalent cations $Sr^2+,\;Zn^2+,\;Cu^2+,\;Fe^2+,\;Co^2+,\;Ba^2+,\;and\;Cd^2+,\;but\;not\;Ca^2+,\;Mn^2+,\;and\;Ni^2+.$ Transport of $Mg^{2}+$ by SLC41Al is rheogenic, voltage dependent, and not coupled to Na or Cl. Expressed SLC41Al transports a range of other divalent cations: $Mg^{2+},\;Sr^{2+},\;Zn^{2+},\;Cu^{2+},\;Fe^{2+},\;Co^{2+},\;Ba^{2+},\;and\;Cd^{2+}$. The divalent cations $Ca^{2+},\;Mn^{2+},\;and\;Ni^{2+}$and the trivalent ion $Gd^{3+}$ did not induce currents nor did they inhibit $Mg^{2+}$ transport. The nonselective cation $La^{3+}$ abolishes $Mg^{2+}$ uptake. Computer analysis of the SLC41Al protein structure reveals that it belongs to MgtE protein family & suggested that the human solute carrier, SLC41Al, might be a eukaryotic $Mg^{2+}$ transporter closely related $(60-70\%)$ protein encoded by SLC41A2 is a $Mg^{2}+$ transporter that might be involved in magnesium homeostasis in epithelial cells also transports a range of other divalent cations: $Ba^2,\;Ni^2,\;CO^2,\;Fe^2,\;or\;Mn^2,\;but\;not\;Ca^2,\;Zn^2,\;or\;Cu^{2+}$ that may have related functional properties.

• The Korean Journal of Physiology
• /
• v.29 no.1
• /
• pp.13-27
• /
• 1995

single $K^{+}$ channels of skeletal muscle from the rat and frog were into planar lipid bilayers and their properties were studied. Fusion was induced by an osmotic gradient. Of the four types of $K^{+}$ channels recorded, the two most frequently observed were a voltage and $Ca^{2+}-activated$ $K^{+}$ channel and a $K^{+}$ channel with a prominent conductance substate. The first $K^{+}$ channel was identified as the large $Ca^{2+}-activated$ $K^{+}$ (BK) channel because the open-state probability was increased with depolarization (e-fold change per $10.6{\pm}3.5$ mV, n=8) and internal $Ca^{2+}$ (half-activation at $16.7{\pm}3.8$ mV, n=8, pCa 4) and its conductance was large ($247{\pm}4.9$ pS, n=24 in 0.1 M KCI). Lifetime distributions of open- and closed-states could be fitted with single exponentials of several milliseconds. The mean open- and closed-lifetimes were linearly dependent on the intracellular $[Ca^{2+}]$ and $1/[Ca^{2+}]$, respectively. The second $K^{+}$ channel showed a conductance substate at $30{\sim}60%$ of the open state. Its current-voltage relation was linear in the range of $-80\;{\sim}\;+80\;mV$. The slope conductance of the substate and open-state were 40 and 144 pS in 0.2 M KCl, respectively. The channel was highly selective for $K^{+}$ over Cl. The open-state probability was weakly voltage-dependent (e-fold change per 35 mV. The lifetime distributions of open- and closed-states were fitted with two exponentials and the major gating occurred slowly at several hundred milliseconds. Based on the above results, we think the second type of $K^{+}$ channel is the sarcoplasmic reticulum $K^{+}$ (SRK) channel. In addition, both types of channel were also incorporated into the lipids extracted from the skeletal muscle. The channel properties recorded in the bilayers termed from synthetic and extracted lipids were qualitatively similar. Our data indicate that BK and SRK channels are rich in the skeletal muscle and their properties and regulation could be effectively studied in planar lipid bilayer.

• Journal of Life Science
• /
• v.21 no.12
• /
• pp.1772-1777
• /
• 2011

Cystic fibrosis transmembrane conductance regulator (CFTR) gene and sodium-independent $Cl^-/HCO_3^-$ anion exchanger (AE) genes are expressed in a wide variety of mammalian tissues including cholangiocytes. They play an important role in the regulation of intracellular pH (pHi) as well as in transepithelial acid/base transport necessary for biliary bicarbonate secretion. The aim of this study was to examine the expression level of CFTR gene and AE genes (AE1, AE2 and AE3) in the cholangiocytes and the hepatocytes, and also measure AE2 gene expression level after bile duct ligation (BDL). As we previously described, isolated hepatocytes and cholangiocytes from the liver of normal and BDL rats were prepared and gene expression levels were measured by using RT-PCR. We found that AE1, AE2, and AE3 genes were expressed in both hepatocytes and cholangiocytes, but CFTR was only in cholangiocytes. AE2 gene expression level was higher in the BDL hepatocytes than normal hepatocytes, which was significantly different between two groups. AE2 gene expression level was lower in the BDL cholangiocytes than normal cholangiocytes. However, AE2 gene expression level in both hepatocytes and cholangiocytes were not changed with a longer duration of BDL. These results suggest that CFTR and AE2 may play an important role in the pathogenetic mechanism of biliary cholestatic liver disease.