Forsythia suspensa Suppresses House Dust Mite Extract-Induced Atopic Dermatitis in NC/Nga Mice.

Forsythia suspensa (F. suspensa) is a traditional medicine for treatment of inflammation. In this study, we evaluated the therapeutic effects of an ethanol extract from F. suspensa fruits on atopic dermatitis both in vivo and in vitro. We investigated the inhibitory effects of F. suspensa extract on the development of atopic dermatitis-like skin lesions in an NC/Nga mouse model exposed to Dermatophagoides farinae crude extract. Topical application of F. suspensa extract to the mice attenuated the atopic dermatitis symptoms, including increased dermatitis severity score, ear thickness, infiltration of inflammatory cells in the skin lesions, serum levels of IgE, TNF-α, and histamine, and expression of chemokines, cytokines, and adhesion molecules in ear tissue. In addition, F. suspensa extract inhibited the production of chemokines in TNF-α/IFN-γ-activated human keratinocytes. High-performance liquid chromatography analysis of FSE revealed the presence of four chemical constituents (forsythiaside, phillyrin, pinoresinol, and phylligenin). These compounds inhibited the production of chemokines in TNF-α/IFN-γ-activated human keratinocytes. These results suggest that the F. suspensa might be a useful candidate for treating allergic skin inflammatory disorders.

2,4-Bis(4-hydroxybenzyl)phenol inhibits heat shock transcription factor 1 and sensitizes lung cancer cells to conventional anticancer modalities.

Heat shock factor 1 (HSF1) is a transcription factor that regulates expression of heat shock protein (HSP) genes in response to stress. HSPs are expressed at high levels in a wide range of tumors. It has been reported that HSF1 and HSPs are associated closely in tumorigenesis. In the present study, a screen was performed using a luciferase reporter under the control of a heat shock element to find inhibitors of HSF1 activity, and 2,4-bis(4-hydroxybenzyl)phenol (1), isolated from the rhizomes of Gastrodia elata, was identified as an active compound. This substance effectively inhibited HSF1 activity and decreased levels of HSP27 and HSP70. Compound 1 induced the degradation of HSF1 protein through dephosphorylation of HSF1 on S326, which decreases HSF1 protein stability. In addition, 1 also induced growth arrest and apoptosis of NCI-H460 human lung cancer cells. Markers of apoptosis, such as cleaved PARP and cleaved caspase-3, were detected after treatment with 1. Furthermore, cotreatment with 1 and conventional anticancer modalities such as paclitaxel, cisplatin, or ionizing radiation potentiated their effects on lung cancer cells. These results suggest that inhibition of HSF1 by 1 may help overcome resistance to conventional anticancer modalities in HSF1-overexpressed cancer cells.

Heat shock factor 1 inducers from the bark of Eucommia ulmoides as cytoprotective agents.

The barks of Eucommia ulmoides (Eucommiae Cortex, Eucommiaceae) have been used as a traditional medicine in Korea, Japan, and China to treat hypertension, reinforce the muscles and bones, and recover the damaged liver and kidney functions. Among these traditional uses, to establish the recovery effects on the damaged organs on the basis of phytochemistry, the barks of E. ulmoides have been investigated to afford three known phenolic compounds, coniferaldehyde glucoside (1), bartsioside (2), and feretoside (3), which were found in the family Eucommiaceae for the first time. The compounds 1-3 were evaluated for their inducible activities on the heat shock factor 1 (HSF1), and heat shock proteins (HSPs) 27 and 70, along with four compounds, geniposide (4), geniposidic acid (5), pinoresinol diglucoside (6), and liriodendrin (7), which were previously reported from E. ulmoides. Compounds 1-7 increased expression of HSF1 by a factor of 1.214, 1.144, 1.153, 1.114, 1.159, 1.041, and 1.167 at 3 µM, respectively. Coniferaldehyde glucoside (1) showed the most effective increase of HSF1 and induced successive expressions of HSP27 and HSP70 in a dose-dependent manner without cellular cytotoxicity, suggesting a possible application as a HSP inducer to act as cytoprotective agent.

Oral administration of a gemini vitamin D analog, a synthetic triterpenoid and the combination prevents mammary tumorigenesis driven by ErbB2 overexpression.

HER2 (or ErbB2), a member of ErbB receptor tyrosine kinases, is overexpressed in approximately 20% of human breast cancer, and the ErbB2 signaling pathway is a critical therapeutic target for ErbB2-overexpressing breast cancer. We investigated the inhibitory effects of the Gemini vitamin D analog BXL0124, the synthetic triterpenoid CDDO-Im and the combination on the tumorigenesis of ErbB2-overexpressing breast cancer. MMTV-ErbB2/neu transgenic mice were treated with BXL0124, CDDO-Im, or the combination from three months of age until the end of the experiment. Formation and growth of MMTV-ErbB2/neu mammary tumors were monitored every week, and all three treatments delayed the development of mammary tumors without significant toxicity. Decreased activation of ErbB2 as well as other ErbB receptors, ErbB1 and ErbB3, in MMTV-ErbB2/neu mammary tumors was shown by all treatments. Protein levels of downstream targets of the ErbB2 signaling pathway, including activated-Erk1/2, activated-Akt, c-Myc, CycD1, and Bcl2, were repressed by all three treatments, with the combination treatment exhibiting the strongest effects. To investigate therapeutic efficacy, the combination of BXL0124 and CDDO-Im was given to MMTV-ErbB2/neu mice after mammary tumors were established between 23 and 30 weeks of age. Short-term treatment with the combination did not show effects on tumor growth nor the ErbB2 signaling pathway. The present study shows BXL0124, CDDO-Im, and the combination as potential agents for prevention, but not treatment, against the tumorigenesis of ErbB2-overexpressing breast cancer.

The Antiobesity Effect of Polygonum aviculare L. Ethanol Extract in High-Fat Diet-Induced Obese Mice.

The antiobesity effects of a P. aviculare ethanol extract (PAE) in high-fat diet- (HFD-) induced obese mice were investigated. The mice were fed an HFD or an HFD supplemented with PAE (400 mg/kg/day) for 6.5 weeks. The increased body weights, adipose tissue weight, and adipocyte area as well as serum total triglyceride, leptin, and malondialdehyde concentrations were decreased in PAE-treated HFD-induced obese mice relative to the same measurements in untreated obese mice. Furthermore, PAE significantly suppressed the elevated mRNA expression levels of sterol regulatory element-binding protein-1c, peroxisome proliferator-activated receptor γ, fatty acid synthase, and adipocyte protein 2 in the white adipose tissue of obese mice. In addition, PAE treatment of 3T3-L1 cells inhibited adipocyte differentiation and fat accumulation in a dose-dependent manner. These results suggest that PAE exerts antiobesity effects in HFD-induced obese mice through the suppression of lipogenesis in adipose tissue and increased antioxidant activity.

Anti­obesity effects of Actinidia polygama extract in mice with high­fat diet­induced obesity.

Actinidia polygama has been used as a herbal folk medicine for treating pain, gout, rheumatoid arthritis and inflammation. In the present study, the anti­obesity properties of Actinidia polygama extract (APE) were investigated in mice with high­fat diet­induced obesity. APE treatment of high­fat diet (HFD)­fed obese mice significantly reduced body weight, adipose tissue mass and serum triglyceride and leptin levels relative to the HFD­fed mice. Food intake did not differ between the HFD and HFD+APE groups, although the food efficiency ratio (FER) was significantly decreased in the HFD+APE group compared with the HFD group. Histological examination showed that the sizes of the adipocytes were significantly smaller in the HFD+APE group compared with the HFD group. Serum levels of aspartate transaminase were significantly decreased in the HFD+APE mice compared with the HFD­fed mice, but serum levels of alanine transaminase (ALT), blood urea nitrogen and creatinine were not significantly changed in the HFD+APE mice compared with the levels in the normal diet (ND)­fed and HFD­fed mice. These results suggest that APE may be useful for treating metabolic diseases, including obesity and hyperlipidemia, without toxic side­effects.

Anti-obesity effects of Geranium thunbergii extract via improvement of lipid metabolism in high-fat diet-induced obese mice.

This study investigated the anti-obesity properties of an extract of Geranium thunbergii (GTE) in high-fat diet-induced obese mice. GTE treatment significantly reduced body weight, adipose tissue mass, adipocyte size, as well as serum triglyceride, total cholesterol and low-density lipoprotein-cholesterol levels in obese mice compared to high-fat diet-fed mice. It also decreased serum leptin levels and increased adiponectin levels. The serum levels of aspartate transaminase, alanine transaminase, blood urea nitrogen and creatinine were not significantly changed in GTE-treated mice compared to serum levels in normal diet and high-fat diet-fed mice. Furthermore, GTE suppressed the mRNA levels of sterol regulatory element-binding protein 1c, peroxisome proliferator-activated receptor γ, adipocyte fatty acid-binding protein and fatty acid synthase in the adipose tissues of obese mice. These results suggest that GTE ameliorated high-fat diet-induced obesity by altering the adipokine levels and downregulating the expression of transcription factors and lipogenic enzymes involved in lipid metabolism.

Anti-obesity activity of Allium fistulosum L. extract by down-regulation of the expression of lipogenic genes in high-fat diet-induced obese mice.

This study investigated the anti-obesity activity and underlying mechanism of a 70% ethanol extract from Allium fistulosum L. (AFE) in high-fat diet-induced obese mice. AFE was orally administered to mice with the high-fat diet at a dose of 400 mg/kg/day for 6.5 weeks. AFE treatment significantly reduced body weight and white adipose tissue (subcutaneous, epididymal and retroperitoneal) weight as well as adipocyte size compared to high-fat diet-induced control mice. AFE also significantly decreased triglyceride, total cholesterol, low density lipoprotein-cholesterol and leptin concentrations in the serum of the mice, whereas it increased adiponectin levels. Furthermore, AFE suppressed the mRNA expression of transcription factors, such as sterol regulatory element binding protein-1c and peroxisome proliferator activated receptor γ, as well as fatty acid synthase in the subcutaneous adipose tissue. These results suggest that AFE inhibited the adipose size, fat accumulation and serum lipid concentrations by down-regulation of the expression of genes involved in lipogenesis in the adipose tissue of high-fat diet-induced obese mice.

Topical application of Rehmannia glutinosa extract inhibits mite allergen-induced atopic dermatitis in NC/Nga mice.

AIM OF THE STUDY: Rehmannia glutinosa is known in Asia as a traditional herbal medicine with anti-inflammatory properties. Atopic dermatitis (AD) is an inflammatory skin disease associated with enhanced T-helper 2 (Th2) lymphocyte responses to allergens that results in elevated serum IgE levels and leukocyte infiltration. Although some studies have shown that Rehmannia glutinosa extract (RGE) has anti-inflammatory and anti-allergic activities, these properties have not been demonstrated in AD. This study investigated the effectiveness of RGE as a therapeutic candidate in an AD model as well as its underlying mechanism of action. MATERIALS AND METHODS: The effects of RGE on mite allergen (Dermatophagoides farinae)-treated NC/Nga mice were evaluated by skin symptom severity, ear thickness, production of serum IgE and histamine, and expression of cytokines, chemokines, and adhesion molecules in the ear lesions. In addition, the levels of thymus and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC), and regulated on activation, normal T cell expressed and secreted (RANTES) produced in both TNF-α- and IFN-γ-stimulated human keratinocytes were investigated by enzyme-linked immunosorbent assay (ELISA). RESULTS: RGE treatment of NC/Nga mice significantly reduced dermatitis scores, ear thicknesses, and serum histamine levels. Histological analyses demonstrated decreased thickening of the epidermis/dermis as well as dermal infiltration by inflammatory cells. In the ear lesions, mRNA expression levels of IL-4, TNF-α, VCAM-1, and ICAM-1 were inhibited by RGE treatment. RGE also suppressed the production of TARC, MDC, and RANTES in both the ear lesions and keratinocytes. CONCLUSIONS: RGE inhibits the development of AD in NC/Nga mice by suppressing the expression of cytokines, chemokines, and adhesion molecules.

Inhibitory effects of Cinnamomum cassia extract on atopic dermatitis-like skin lesions induced by mite antigen in NC/Nga mice.

AIM OF THE STUDY: Cinnamomum cassia (C. cassia) has been traditionally used to treat allergic disease as well as dyspepsia, gastritis, and blood circulation disturbances. However, the antiallergic properties of C. cassia have not been fully verified using scientific tools. This study investigated the effectiveness of C. cassia extract (CCE) as an antiallergic agent in atopic dermatitis model and underlying mechanism. MATERIALS AND METHODS: The effect of CCE on mite antigen-treated NC/Nga mice was evaluated by examining skin symptom severity, levels of serum IgE, tumor necrosis factor-α (TNF-α), and histamine, skin histology, and mRNA expression of cytokines in the skin lesions. Moreover, the effect of CCE on TNF-α-and interferon-γ (IFN-γ)-induced chemokine production in human keratinocytes was investigated using ELISA. RESULTS: CCE treatment of NC/Nga mice reduced the dermatitis score and the levels of serum IgE, histamine, and TNF-α. Histological examination showed inhibition of the thickening of the epidermis/dermis and reduced dermal infiltration of inflammatory cells. In skin lesions, mRNA expression of IL-4, TNF-α, and thymus and activation-regulated chemokine (TARC) was inhibited by CCE treatment. The production of TARC, macrophage-derived chemokine, and RANTES from IFN-γ-and TNF-α-stimulated human keratinocytes was suppressed by CCE treatment in a dose-dependent manner. CONCLUSIONS: CCE inhibits the development of atopic dermatitis-like skin lesions in NC/Nga mice by suppressing the T-helper 2 cell response.

Anti-inflammatory effects of Glehnia littoralis extract in acute and chronic cutaneous inflammation.

Glehnia littoralis (Umbelliferae) is a traditional medicine used in Korea, China, and Japan to treat the immune-related diseases. However, its anti-inflammatory activities and mechanisms remain to be defined. We investigated the effects of 70% ethanolic extract from G. littoralis (GLE) on skin inflammation in mice. Production of proinflammatory cytokines (IL-1ß and TNF-α), activation of myeloperoxidase (MPO), and histological indicators were examined in acute and chronic skin inflammation using 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced mouse ear edema. We also performed acetic acid-induced vascular permeability tests. GLE treatment at 200 mg/kg inhibited topical edema in the mouse ear, leading to substantial reductions in skin thickness and tissue weight, inflammatory cytokine production, neutrophil-mediated MPO activity, and several histopathological indicators. Furthermore, GLE effectively reduced inflammatory damage induced by chronic TPA exposure and significantly inhibited the vascular permeability induced by acetic acid in mice. These results suggest that G. littoralis is an effective anti-inflammatory agent in murine phorbol ester-induced dermatitis and may have therapeutic potential in a variety of immune-related cutaneous diseases.

Anti-inflammatory activity of methylene chloride fraction from Glehnia littoralis extract via suppression of NF-kappa B and mitogen-activated protein kinase activity.

Glehnia littoralis (Umbelliferae) has been used traditionally in Korean, Japanese, and Chinese medicine for the treatment of immune-related diseases; however, its anti-inflammatory activity and underlying mechanism remain to be defined. We investigated the anti-inflammatory effect and inhibitory mechanism on inflammation by the methylene chloride fraction from Glehnia littoralis extract (MCF-GLE), which was more effective than Glehnia littoralis extract (GLE). MCF-GLE inhibited 12-O-Tetradecanoyl-phorbol-13-acetate (TPA)-induced inflammation in an inflammatory edema mouse model. Also, MCF-GLE strongly inhibited the releases of nitric oxide (NO), prostaglandin E(2) (PGE(2)), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta) and significantly suppressed the mRNA and protein expression of inducible nitric oxide synthase and cyclooxygenase-2 in lipopolysaccharide-stimulated RAW 264.7 macrophage cells in a dose-dependent manner. Furthermore, MCF-GLE suppressed NF-kappaB activation and IkappaB-alpha degradation. MCF-GLE also attenuated the activation of ERK and JNK in a dose-dependent manner. These results indicate that MCF-GLE has an inhibitory effect on the in vivo and in vitro inflammatory reaction and is a possible therapeutic agent. Our results suggest that the anti-inflammatory properties of MCF-GLE may result from the inhibition of pro-inflammatory mediators, such as NO, PGE(2), TNF-alpha, and IL-1beta via suppression of NF-kappaB- and mitogen-activated protein kinases-dependent pathways.

Chrysanthemum indicum Linné extract inhibits the inflammatory response by suppressing NF-kappaB and MAPKs activation in lipopolysaccharide-induced RAW 264.7 macrophages.

AIMS OF STUDY: Although the flowers of Chrysanthemum indicum Linné (Asteraceae) have long been used in traditional Korean and Chinese medicine to treat inflammatory diseases, the underlying mechanism(s) by which these effects are induced remains to be defined. We investigated the effects of a 70% ethanolic extract of C. indicum (CIE) on the activities of cellular signaling molecules that mediate inflammatory responses. MATERIALS AND METHODS: Production of NO, PGE(2), TNF-alpha, and IL-1beta by ELISA, mRNA and protein expression of iNOS and COX-2, phosphorylation of MAPKs, and activation of NF-kappaB by RT-PCR and Western blotting were examined in LPS-induced RAW 264.7 macrophages. RESULTS: The CIE strongly inhibited NO, PGE(2), TNF-alpha, and IL-1beta production, and also significantly inhibited mRNA and protein expression of iNOS and COX-2 in LPS-induced RAW 264.7 macrophages, in a dose-dependent manner. Furthermore, the CIE clearly suppressed nuclear translocation of NF-kappaB p65 subunits, which correlated with an inhibitory effect on IkappaBalpha phosphorylation. The CIE also attenuated the activation of ERK1/2 and JNK in a dose-dependent manner. CONCLUSION: Our results suggest that the anti-inflammatory properties of CIE might result from the inhibition of inflammatory mediators, such as NO, PGE(2), TNF-alpha, and IL-1beta, via suppression of MAPKs and NF-kappaB-dependent pathways.

Anti-inflammatory activity of Chrysanthemum indicum extract in acute and chronic cutaneous inflammation.

AIM OF THE STUDY: Although Chrysanthemum indicum Linné (Compositae) has long been used in traditional Korean, Chinese, Japanese medicine to treat various immune-related diseases the underlying mechanism(s) by which these effects are induced remains to be defined in vivo model system. We investigated the effects of 70% ethanolic extract from Chrysanthemum indicum Linné (CIE) on skin inflammation in mice. MATERIALS AND METHODS: Production of pro-inflammatory cytokines (TNF-alpha and IL-1 beta), activation of myeloperoxidase, and histological assessment were examined in acute and chronic skin inflammation using 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced mouse ear edema. RESULTS: CIE inhibited topical edema in the mouse ear, following administration at 200mg/kg (i.p.), leading to substantial reductions in skin thickness and tissue weight, inflammatory cytokine production, neutrophil-mediated myeloperoxidase activity, and various histopathological indicators. Furthermore, CIE was effective at reducing inflammatory damage induced by chronic TPA exposure. CONCLUSIONS: These results demonstrate that CIE is an effective anti-inflammatory agent in murine phorbol ester-induced dermatitis, and suggest that the extract may have therapeutic potential in a variety of immune-related cutaneous diseases.

Development of SCAR markers for the discrimination of three species of medicinal plants, Angelica decursiva (Peucedanum decursivum), Peucedanum praeruptorum and Anthricus sylvestris, based on the internal transcribed spacer (ITS) sequence and random amplified polymorphic DNA (RAPD).

Angelicae decursivae radix ('Jeonho' in Korean) is prescribed as the root of Angelica decursiva (= Peucedanum decursivum) and Peucedanum praeruptorum in Korean pharmacopoeia. However, Anthricus sylvestris has been usually distributed on the market because it is identical to the Korean plant name 'Jeonho'. Furthermore, due to the morphological similarity of the aerial parts and herbal medicines, the correct identification of these roots is difficult. Therefore, to develop a reliable method for discriminating among A. decursiva (= P. decursivum), P. praeruptorum and A. sylvestris, we applied the tools of molecular genetics, such as the analysis of ribosomal DNA internal transcribed spacer (rDNA-ITS) and random amplified polymorphic DNA (RAPD). In the comparison of rDNA-ITS sequences, we found a specific primer region for the identification of A. sylvestris among three varieties of the herb that produced a 273 bp strand of DNA specific to A. sylvestris. As the result of RAPD analysis, we developed one sequence characterized amplified region (SCAR) marker for A. decursiva and P. praeruptorum that amplified a 363 bp DNA fragment specific to both A. decursiva and P. praeruptorum and two markers for P. praeruptorum that amplified 145 bp and 305 bp DNA fragments specific to P. praeruptorum. Furthermore, we established the SCAR markers for the simultaneous discrimination of the three species by applying a multiplex-polymerase chain reaction (PCR) with a combination of primers. This method of discrimination would be useful in preventing the distribution of adulterates because it can identify each herb and distinguish it from inauthentic substitutions.

Anti-inflammatory effects of Asparagus cochinchinensis extract in acute and chronic cutaneous inflammation.

AIMS OF STUDY: Although Asparagus cochinchinensis Merrill (Liliaceae) has long been used in traditional Korean and Chinese medicine to treat inflammatory diseases, the underlying mechanism(s) by which these effects are induced remains to be defined. We investigated the effects of 70% ethanolic extract from Asparagus cochinchinensis Merrill (ACE) on skin inflammation in mice. MATERIALS AND METHODS: Production of pro-inflammatory cytokines (tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta), activation of myeloperoxidase, and histological assessment were examined in acute and chronic skin inflammation using 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced mouse ear edema. We also performed acetic acid-induced vascular permeability test. RESULTS: ACE inhibited topical edema in the mouse ear, following administration at 200mg/kg (i.p.), leading to substantial reductions in skin thickness and tissue weight, inflammatory cytokine production, neutrophil-mediated myeloperoxidase (MPO) activity, and various histopathological indicators. Furthermore, ACE was effective at reducing inflammatory damage induced by chronic TPA exposure and evoked a significant inhibition of vascular permeability induced by acetic acid in mice. CONCLUSION: These results demonstrate that ACE is an effective anti-inflammatory agent in murine phorbol ester-induced dermatitis, and suggest that the compound may have therapeutic potential in a variety of immune-related cutaneous diseases.

Inhibition of Na,K-ATPase-suppressive activity of translationally controlled tumor protein by sorting nexin 6.

Translationally controlled tumor protein (TCTP) has both extra- and intracellular functions. Our group recently reported that TCTP interacts with Na,K-ATPase and suppresses its activity. Our studies led to the identification of sorting nexin 6 (SNX6) which binds with TCTP as a potential negative regulator of TCTP. SNX6 does not interact directly with any cytoplasmic domains of Na,K-ATPase. However, when overexpressed, it restores the Na,K-ATPase activity suppressed by TCTP. This was confirmed by measurements of purified plasma membrane Na,K-ATPase activity after incubation with recombinant TCTP and SNX6. SNX6 alone has no effect on Na,K-ATPase activity, but activates Na,K-ATPase via inhibition of TCTP. Inhibition of endogenous TCTP by the overexpression of SNX6 or knockdown of TCTP expression by siTCTP increased Na,K-ATPase activity above the basal level. The interaction between SNX6 and TCTP thus appears to regulate Na,K-ATPase activity.

Homo- or hetero-dimerization of muscarinic receptor subtypes is not mediated by direct protein-protein interaction through intracellular and extracellular regions.

The oligomerization of G-proteincoupled receptors (GPCRs) has been shown to occur by various mechanisms, such as via disulfide covalent linkages, noncovalent (ionic, hydrophobic) interactions of the N-terminal, and/or transmembrane and/or intracellular domains. Interactions between GPCRs could involve an association between identical proteins (homomers) or non-identical proteins (heteromers), or between two monomers (to form dimers) or multiple monomers (to form oligomers). It is believed that muscarinic receptors may also be arranged into dimeric or oigomeric complexes, but no systematic experimental evidence exists concerning the direct physical interaction between receptor proteins as its mechanism. We undertook this study to determine whether muscarinic receptors form homomers or a heteromers by direct protein-protein interaction within the same or within different subtypes using a yeast two-hybrid system. Intracellular loops (i1, i2 and i3) and the C-terminal cytoplasmic tails (C) of human muscarinic (Hm) receptor subtypes, Hm1, Hm2 and Hm3, were cloned into the vectors (pB42AD and pLexA) of a two-hybrid system and examined for heteromeric or homodimeric interactions between the cytoplasmic domains. No physical interaction was observed between the intracellular domains of any of the Hm/Hm receptor sets tested. The results of our study suggest that the Hm1, Hm2 and Hm3 receptors do not form dimers or oligomers by interacting directly through either the hydrophilic intracellular domains or the C-terminal tail domains. To further investigate extracellular domain interactions, the N-terminus (N) and extracellular loops (o1 and o2) were also cloned into the two-hybrid vectors. Interactions of Hm2N with Hm2N, Hm2o1, Hm2o2, Hm3N, Hm3o1 or Hm3o2 were examined. The N-terminal domain of Hm2 was found to have no direct interaction with any extracellular domain. From our results, we excluded the possibility of a direct interaction between the muscarinic receptor subtypes (Hm1, Hm2 and Hm3) as a mechanism for homo- or hetero-meric dimerization/oligomerization. On the other hand, it remains a possibility that interaction may occur indirectly or require proper conformation or subunit formation or hydrophobic region involvement.

Interaction of cofilin with triose-phosphate isomerase contributes glycolytic fuel for Na,K-ATPase via Rho-mediated signaling pathway.

We reported previously that cofilin, an actin-binding protein, interacts with Na,K-ATPase and enhances its activity (Lee, K., Jung, J., Kim, M., and Guidotti, G. (2001) Biochem. J. 353, 377-385). To understand the nature of this interaction and the role of cofilin in the regulation of Na,K-ATPase activity, we searched for cofilin-binding proteins in the rat skeletal muscle cDNA library using the yeast two-hybrid system. Several cDNA clones were isolated, some of which coded for triose-phosphate isomerase, a glycolytic enzyme. The interaction of cofilin with triose-phosphate isomerase as well as Na,K-ATPase was confirmed by immunoprecipitation and confocal microscopy in HeLa cells. Cofilin was translocated to the plasma membrane along with triose-phosphate isomerase by the Rho activator lysophosphatidic acid but not by the p160 Rho-associated kinase inhibitor Y-27632, suggesting that the phosphorylated form of cofilin bound to TPI interacts with Na,K-ATPase. Ouabain-sensitive (86)Rb(+) uptake showed that Na,K-ATPase activity was increased by the overexpression of cofilin and lysophosphatidic acid treatment, but not by the overexpression of mutant cofilin S3A and Y-27632 treatment. Pretreatment with the glycolytic inhibitor iodoacetic acid caused a remarkable reduction of Na,K-ATPase activity, whereas pretreatment with the oxidative inhibitor carbonyl cyanide m-chlorophenylhydrazone caused no detectable changes, suggesting that the phosphorylated cofilin is involved in feeding glycolytic fuel for Na,K-ATPase activity. These findings provide a novel molecular mechanism for the regulation of Na,K-ATPase activity and for the nature of the functional coupling of cellular energy transduction.