TRPC5 as a candidate for the nonselective cation channel activated by muscarinic stimulation in murine stomach

We investigated which transient receptor potential (TRP) channel is responsible for the nonselective cation channel (NSCC) activated by carbachol (CCh) in murine stomach with RT-PCR and the electrophysiological method. All seven types of TRP mRNA were detected in murine stomach with RT-PCR. When each TRP channel was expressed, the current-voltage relationship of mTRP5 was most similar to that recorded in murine gastric myocytes. mTRP5 showed a conductance order of Cs(+) > K(+) > Na(+), similar to that in the murine stomach. With 0.2 mM GTPgammaS in the pipette solution, the current was activated transiently in both NSCC in the murine stomach and the expressed mTRP5. Both NSCC activated by CCh in murine stomach and mTRP5 were inhibited by intracellularly applied anti-G(q/11) antibody, PLC inhibitor U-73122, IICR inhibitor 2-aminoethoxydiphenylborate, and nonspecific cation channel blockers La(3+) and flufenamate. There were two other unique properties. Both the native NSCC and mTRP5 were activated by 1-oleoyl-2-acetyl-sn-glycerol. Without the activation of NSCC by CCh, the NSCC in murine stomach was constitutively active like mTRP5. From the above results, we suggest that mTRP5 might be a candidate for the NSCC activated by ACh or CCh in murine stomach.

Suppression of transient receptor potential melastatin 7 channel induces cell death in gastric cancer

Ca2+ and Mg2+ have a fundamental role in many cellular processes and ion channels are involved in normal physiologic processes and in the pathology of various diseases. The aim here was to show that the presence and potential role of transient receptor potential melastatin 7 (TRPM7) channels in the growth and survival of AGS cells, the most common human gastric adenocarcinoma cell line. The patch-clamp technique for whole-cell recording was used in AGS cells. TRPM7-specific small interfering RNAs were used for specific inhibition of TRPM7. Whole-cell voltage-clamp recordings revealed the TRPM7-like currents that activated spontaneously following loss of intracellular Mg2+. The current had a non-linear current-voltage relationship with the characteristic steep outward rectification associated with TRPM7 channels. Reverse transcription-polymerase chain reaction, western blotting, and immunoreactivity all showed abundant expression of TRPM7 messenger RNA and protein in AGS cells. Transfection of AGS cells with TRPM7 siRNA significantly reduced the expression of TRPM7 mRNA and protein as well as the amplitude of the TRPM7-like currents. Furthermore, we found that Mg2+ is critical for the growth and survival in AGS cells. Blockade of TRPM7 channels by La3+ and 2-APB or suppression of TRPM7 expression by siRNA inhibited the growth and survival of these cells. Human gastric adenocarcinoma cells express TRPM7 channel whose presence is essential for cell survival. The protein is a likely potential target for the pharmacological treatment of gastric cancer.

Melastatin-type transient receptor potential channel 7 is required for intestinal pacemaking activity

BACKGROUND & AIMS

Interstitial cells of Cajal are pacemakers in the gastrointestinal tract, regulating rhythmicity by activating nonselective cation channels. In Caenorhabditis elegans, the melastatin-type transient receptor potential (TRPM) channel, especially TRPM7, was suggested as being involved in defecation rhythm. The aim here was to show that the nonselective cation channel in interstitial cells of Cajal in mouse small intestine has properties essentially identical to those of murine TRPM7, heterologously expressed in human embryonic kidney cells.

METHODS

The patch-clamp technique for whole-cell recording was used in cultured or single interstitial cells of Cajal. TRPM7-specific small interfering RNAs were used for specific inhibition of TRPM7.

RESULTS

Electrophysiological and pharmacological properties of the nonselective cation channel in interstitial cells of Cajal were the same as those of TRPM7. Reverse-transcription polymerase chain reaction, Western blotting, and immunohistochemistry all showed abundant and localized expression of TRPM7 messenger RNA and protein in mouse small intestine. Treatment of primary cultured interstitial cells of Cajal with TRPM7-specific small interfering RNA resulted in inhibition of pacemaking activity.

CONCLUSIONS

TRPM7 is required for intestinal pacemaking. The protein is a likely potential target for pharmacological treatment of motor disorders of the gut.

NOX4 as an oxygen sensor to regulate TASK-1 activity

When oxygen sensing cells are excited by hypoxia, background K+ currents are inhibited. TASK-1, which is commonly expressed in oxygen sensing cells and makes a background K+ current, is inactivated by hypoxia. Thus TASK-1 is a candidate molecule responsible for hypoxic excitation. However, TASK-1 per se cannot sense oxygen and may require a regulatory protein that can. In the present study, we propose that the NADPH oxidase NOX4 functions as an oxygen-sensing partner and that it modulates the oxygen sensitivity of TASK-1. Confocal imaging revealed the co-localization of TASK-1 and NOX4 in the plasma membrane. In HEK293 cells expressing NOX4 endogenously, the activity of expressed TASK-1 was moderately inhibited by hypoxia, and this oxygen response was significantly augmented by NOX4. Moreover, the oxygen sensitivity of TASK-1 was abolished by NOX4 siRNA and NADPH oxidase inhibitors. These results suggest a novel function for NOX4 in the oxygen-dependent regulation of TASK-1 activity.

Poria cocus Wolf Extract Ameliorates Hepatic Steatosis through Regulation of Lipid Metabolism, Inhibition of ER Stress, and Activation of Autophagy via AMPK Activation

Poria cocos Wolf (PCW) is an edible, pharmaceutical mushroom with remarkable biological properties including anti-tumor, anti-inflammation, anti-oxidation, anti-ageing, and anti-diabetic effects. In the current study, we investigated the effects of PCW extract on hepatic steatosis under in vitro and in vivo conditions, and elucidated the underlying mechanisms. In this study, a mixture of HepG2 cells treated with free fatty acid (FFA)-palmitic and oleic acid-and high-fat diet (HFD)-fed obese mice were used; in this background, the triglyceride (TG) levels in HepG2 cells and mice liver were measured, and the expression levels of genes associated with lipogenesis, fatty acid oxidation, endoplasmic reticulum (ER) stress, and autophagy were determined. Treatment of HepG2 cells with FFA enhanced intracellular TG levels in HepG2 cells, but co-treatment with PCW significantly attenuated the TG levels. Notably, PCW significantly enhanced the phosphorylation of AMP-activated protein kinase (AMPK), acetyl-CoA carboxylase (ACC), and sterol regulatory element-binding protein-1c (SREBP-1c) in FFA-treated HepG2 cells. PCW downregulated the expression of lipogenesis-related genes, but upregulated the expression of genes associated with fatty acid oxidation. Further, PCW inhibited FFA-induced expression of ER stress markers and induced autophagy proteins. However, inhibition of AMPK significantly attenuated the beneficial effects of PCW in HepG2 cells. Moreover, PCW efficiently decreased HFD-induced hepatic TG accumulation in vivo and increased the phosphorylation of hepatic AMPK. Three compounds present in PCW including poricoic acid, pachymic acid, and ergosterol, significantly decreased FFA-induced increase in intracellular TG levels, consistent with increased AMPK phosphorylation, suggesting that poricoic acid, pachymic acid, and ergosterol are responsible for PCW-mediated amelioration of hepatic steatosis. Taken together, these results demonstrated that PCW ameliorates hepatic steatosis through the regulation of lipid metabolism, inhibition of ER stress, and activation of autophagy in an AMPK-dependent manner. This suggested that PCW can be potentially used for the treatment of hepatic steatosis.

Involvement of melastatin type transient receptor potential 7 channels in ginsenoside Rd-induced apoptosis in gastric and breast cancer cells

Ginsenoside, one of the active ingredients of Panax ginseng, has a variety of physiologic and pharmacologic effects. The purpose of this study was to explore the effects of ginsenoside Rd (G-Rd) on melastatin type transient receptor potential 7 (TRPM7) channels with respect to the proliferation and survival of AGS and MCF-7 cells (a gastric and a breast cancer cell line, respectively). AGS and MCF-7 cells were treated with different concentrations of G-Rd, and caspase-3 activities, mitochondrial depolarizations, and sub-G1 fractions were analyzed to determine if cell death occurred by apoptosis. In addition, human embryonic kidney (HEK) 293 cells overexpressing TRPM7 channels were used to confirm the role of TRPM7 channels. G-Rd inhibited the proliferation and survival of AGS and MCF-7 cells and enhanced caspase-3 activity, mitochondrial depolarization, and sub-G1 populations. In addition, G-Rd inhibited TRPM7-like currents in AGS and MCF-7 cells and in TRPM7 channel overexpressing HEK 293 cells, as determined by whole cell voltage-clamp recordings. Furthermore, TRPM7 overexpression in HEK 293 cells promoted G-Rd induced cell death. These findings suggest that G-Rd inhibits the proliferation and survival of gastric and breast cancer cells by inhibiting TRPM7 channel activity.

Geraniol inhibits prostate cancer growth by targeting cell cycle and apoptosis pathways

The progression of prostate cancer is associated with escape from cell cycle arrest and apoptosis under androgen-depleted conditions. Here, we found that geraniol, a naturally occurring monoterpene, induces cell cycle arrest and apoptosis in cultured cells and tumor grafted mice using PC-3 prostate cancer cells. Geraniol modulated the expression of various cell cycle regulators and Bcl-2 family proteins in PC-3 cells in vitro and in vivo. Furthermore, we showed that the combination of sub-optimal doses of geraniol and docetaxel noticeably suppresses prostate cancer growth in cultured cells and tumor xenograft mice. Therefore, our findings provide insight into unraveling the mechanisms underlying escape from cell cycle arrest and apoptosis and developing therapeutic strategies against prostate cancer.

Transient receptor potential melastatin 7 channels are involved in ginsenoside Rg3-induced apoptosis in gastric cancer cells

Ginsenosides play a role in a number of physiological and pharmacological functions in the gastrointestinal tract. The aim of this study was to clarify the potential role for transient receptor potential melastatin 7 (TRPM7) channels in ginsenoside Rg3-inhibited growth and survival of AGS cells, the most common human gastric adenocarcinoma cell line. The AGS cells were treated with varying concentrations of Rg3. Sub-G1 analysis, caspase-3 activity and poly(ADP-ribose) polymerase (PARP) cleavage analysis were conducted to determine whether AGS cell death occurs by apoptosis. TRPM7 channel blockers (La(3+) or 2-APB) and small interfering RNA (siRNA) were used in this study to confirm the role of TRPM7 channels. Furthermore, TRPM7 channels were over-expressed in human embryonic kidney (HEK) 293 cells to identify the role of TRPM7 channels in AGS cell growth and survival. The addition of Rg3 to the culture medium inhibited AGS growth and survival. Experimental results showed sub-G1 was markedly increased, caspase-3 activity was elevated, and degree of PARP cleavage was increased. TRPM7 channel blockade, either by La(3+) or 2-APB or by suppressing TRPM7 expression with siRNA, blocked the Rg3-induced inhibition of cell growth and survival. Furthermore, TRPM7 channel over-expression in HEK 293 cells exacerbated Rg3-induced cell death. These findings indicate that ginsenoside Rg3 inhibits the growth and survival of gastric cancer cell which is because of the blockade of TRPM7 channel activity. Therefore, TRPM7 channels may play an important role in the survival of gastric cancer.

Electrothermal adsorption and desorption of volatile organic compounds on activated carbon fiber cloth

Adsorption is an effective means to selectively remove volatile organic compounds (VOCs) from industrial gas streams and is particularly of use for gas streams that exhibit highly variable daily concentrations of VOCs. Adsorption of such gas streams by activated carbon fiber cloths (ACFCs) and subsequent controlled desorption can provide gas streams of well-defined concentration that can then be more efficiently treated by biofiltration than streams exhibiting large variability in concentration. In this study, we passed VOC-containing gas through an ACFC vessel for adsorption and then desorption in a concentration-controlled manner via electrothermal heating. Set-point concentrations (40-900 ppm(v)) and superficial gas velocity (6.3-9.9 m/s) were controlled by a data acquisition and control system. The results of the average VOC desorption, desorption factor and VOC in-and-out ratio were calculated and compared for various gas set-point concentrations and superficial gas velocities. Our results reveal that desorption is strongly dependent on the set-point concentration and that the VOC desorption rate can be successfully equalized and controlled via an electrothermal adsorption system.

Schisandra chinensis extract ameliorates nonalcoholic fatty liver via inhibition of endoplasmic reticulum stress

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis (Turcz.) Baill. (SC) is a traditional Chinese herbal medicine with diverse pharmacological activities for treatment of various human diseases. Endoplasmic reticulum (ER) stress is associated with the pathogenesis of nonalcoholic fatty liver disease (NAFLD). In this study, we investigated the protective effects of methanol extract of Schisandra chinensis (SC extract) against ER stress-induced NAFLD in vitro and in vivo.

MATERIAL AND METHODS

The protective effects of SC extract were examined in tunicamycin- or palmitate-treated HepG2 cells in vitro, and in tunicamycin-injected mice or high fed diet (HFD) obese mice in vivo. Expression of ER stress markers including glucose regulated protein 78 (GRP78), C/EBP homolog protein (CHOP), and X-box-binding protein-1 (XBP-1), and triglyceride accumulation were measured in HepG2 cells and in the liver of mice.

RESULTS

SC extract significantly inhibited expression of tunicamycin-induced ER stress markers in tunicamycin-treated HepG2 cells and in the liver of tunicamycin-injected mice, and it also inhibited tunicamycin-induced triglyceride accumulation. Similar observations were made under physiological ER stress conditions such as in palmitate-treated HepG2 cells and in the liver of HFD obese mice. In addition, SC extract repressed the expression of inflammatory genes and lipogenic genes in palmitate-treated HepG2 cells. Schisandrin, an abundant bioactive lignan in SC extract, inhibited the expression of ER stress markers in tunicamycin-or palmitate-treated HepG2 cells, whereas Gomisin J did not affect ER stress markers.

CONCLUSIONS

SC attenuates ER stress and prevents development of NAFLD. SC may be useful as a pharmacological agent for protection against ER stress-induced human diseases.

The Pathophysiologic Roles of TRPM7 Channel

Transient receptor potential melastatin 7 (TRPM7) is a member of the melastatin-related subfamily and contains a channel and a kinase domain. TRPM7 is known to be associated with cell proliferation, survival, and development. It is ubiquitously expressed, highly permeable to Mg(2+) and Ca(2+), and its channel activity is negatively regulated by free Mg(2+) and Mg-complexed nucleotides. Recent studies have investigated the relationships between TRPM7 and a number of diseases. TRPM7 regulates cell proliferation in several cancers, and is associated with ischemic cell death and vascular smooth muscle cell (VSMC) function. This review discusses the physiologic and pathophysiologic functions and significance of TRPM7 in several diseases.

The role of transient receptor potential channel blockers in human gastric cancer cell viability

Transient receptor potential cation channel, subfamily M, receptor 7 (TRPM7) is a ubiquitous divalent-selective ion channel with its own kinase domain. Human gastric cancer cells express the TRPM7 channel, and the presence of this channel is essential for cell survival. Recent studies have suggested that 5-lipoxygenase (5-LOX) inhibitors are potent blockers of the TRPM7 channels. The aim of this study was to show the effects of 5-LOX inhibitors on the growth and survival of gastric cancer cells. Among 5-LOX inhibitors, nordihydroguaiaretic acid (NDGA), 2,3,5-trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone (AA861), and 3-[1-(p-chlorobenzyl)-5-(isopropyl)-3-tert-butylthioindol-2-yl]-2,2-dimethylpropanoic acid (MK886) were potent blockers of TRPM7-like currents in gastric cancer cells and also induced cell death. However, zileuton was ineffective in suppressing TRPM7-like current activity and inducing cell death. Moreover, a specific transient receptor potential cation channel, subfamily C, member 3 (TRPC3) inhibitor, a pyrazole compound (Pyr3), and a specific melastatin TRP (TRPM4) inhibitor, 9-phenanthrol, did not affect TRPM7-like currents or induce cell death. We conclude that TRPM7 has an important role in the growth and survival of gastric cancer cells and a likely potential target for the pharmacological treatment of gastric cancer.

Quercetin induces apoptosis by inhibiting MAPKs and TRPM7 channels in AGS cells

The worldwide incidence and mortality rate of gastric cancer remain high, and thus, novel treatment concepts are required. Quercetin, a bioflavonoid, has been proposed to have anti-cancer properties. The aim of this study was to determine the nature of the apoptotic mechanisms responsible for the effects of quercetin on AGS cells (a commonly used human gastric adenocarcinoma cell line). AGS cell viability was assessed by MTT assay and flow cytometric analysis, mitochondrial membrane depolarization was assessed, and caspase-3 was used to determine the involvement of apoptosis. Whole-cell configuration patch-clamp experiments were used to regulate the transient receptor potential melastatin (TRPM)7 channels. To investigate the signaling pathway of quercetin-induced apoptosis in the AGS cells, western blot analysis and MTT assay were performed. Quercetin was found to induce the apoptosis of these cells, and this apoptosis was inhibited by SB203580 (a p38 kinase inhibitor), SP600125 (a JNK inhibitor) and PD98059 (an ERK inhibitor). In addition, quercetin inhibited TRPM7 currents in the AGS cells and in human embryo kidney (HEK)293 cells which overexpress TRPM7 channels. Furthermore, treatment with quercetin increased the apoptosis of HEK293 cells, which overexpress TRPM7, indicating that the upregulation of TRPM7 channels underlies quercetin-induced cell death. These results suggest that quercetin plays an important pathophysiological role in AGS cells through mitogen‑activated protein kinase (MAPK) signaling pathways and TRPM7 channels, and that quercetin has potential as a pharmacological agent for the treatment of gastric cancer.

Protective Effects of Alisma orientale Extract against Hepatic Steatosis via Inhibition of Endoplasmic Reticulum Stress

Endoplasmic reticulum (ER) stress is associated with the pathogenesis of hepatic steatosis. Alisma orientale Juzepzuk is a traditional medicinal herb for diuretics, diabetes, hepatitis, and inflammation. In this study, we investigated the protective effects of methanol extract of the tuber of Alisma orientale (MEAO) against ER stress-induced hepatic steatosis in vitro and in vivo. MEAO inhibited the tunicamycin-induced increase in luciferase activity of ER stress-reporter constructs containing ER stress response element and ATF6 response element. MEAO significantly inhibited tunicamycin-induced ER stress marker expression including GRP78, CHOP, and XBP-1 in tunicamycin-treated Human hepatocellular carcinoma (HepG2) cells and the livers of tunicamycin-injected mice. It also inhibited tunicamycin-induced accumulation of cellular triglyceride. Similar observations were made under physiological ER stress conditions such as in palmitate (PA)-treated HepG2 cells and the livers of high-fat diet (HFD)-induced obese mice. MEAO repressed hepatic lipogenic gene expression in PA-treated HepG2 cells and the livers of HFD obese mice. Furthermore, MEAO repressed very low-density lipoprotein receptor (VLDLR) expression and improved ApoB secretion in the livers of tunicamycin-injected mice or HFD obese mice as well as in tunicamycin or PA-treated HepG2 cells. Alismol, a guaiane-type sesquiterpenes in Alisma orientale, inhibited GRP78 expression in tunicamycin-treated HepG2 cells. In conclusion, MEAO attenuates ER stress and prevents hepatic steatosis pathogenesis via inhibition of expression of the hepatic lipogenic genes and VLDLR, and enhancement of ApoB secretion.

Menthol regulates TRPM8-independent processes in PC-3 prostate cancer cells

Menthol, a naturally occurring compound from peppermint oil, binds and activates the TRPM8 Ca(2+)-permeable channel that exhibits abnormal expression patterns in prostate cancer, suggesting that TRPM8 links Ca(2+) transport pathways to tumor biology. We thus investigated the cellular responses of prostate cancer cells to menthol. Here we found that menthol increases [Ca(2+)](i) via Ca(2+) influx mechanism(s) independent of TRPM8 in PC-3 cells. We demonstrated that menthol induces cell death at supramillimolar concentrations in PC-3 cells and the cell death is not suppressed by low extracellular Ca(2+) condition which indicates that menthol-induced cell death is not associated with Ca(2+) influx pathways. In addition, we showed that menthol increases a phosphorylated form of c-jun N-terminal kinase (JNK) in PC-3 cells through TRPM8-independent mechanisms. Thus, our data indicate that there is an apparent lack of causality between TRPM8 activation and menthol-induced cell death and that menthol can regulate TRPM8-independent Ca(2+)-transport and cellular processes.

The role of waixenicin A as transient receptor potential melastatin 7 blocker

Transient receptor potential melastatin 7 (TRPM7) plays a role in a number of physiological and pharmacological functions in variety of cells. The aim of this study was to clarify the role for TRPM7 channels and the effect of waixenicin A on the pacemaking activity of interstitial cells of Cajal (ICCs) and on the cell viability of the human gastric and breast adenocarcinoma cell lines, AGS and MCF-7, respectively. Waixenicin A decreased the amplitude of pacemaker potentials in cultured ICC clusters and inhibited TRPM7 currents, but had no effect on Ca(2+) -activated Cl(-) conductance (ANO1). Furthermore, waixenicin A was found to inhibit the growth and survival of AGS and MCF-7 cells. These findings indicate that TRPM7 channel modulates intestinal motility and regulates the pathophysiology of human gastric and breast adenocarcinoma cells. These findings suggest that TRPM7 channel be considered a potential target for the treatment of gut motor disorders and gastric and breast cancer.

Atopic dermatitis phenotype with early onset and high serum IL-13 is linked to the new development of bronchial hyperresponsiveness in school children

BACKGROUND

Atopic dermatitis (AD) is characterized by a heterogeneous clinical spectrum, and some forms of AD are associated with the initial steps of allergic march. The aims of this study were to determine AD phenotypes in school-age children and investigate their associations with the allergic march in each cluster.

METHODS

We included 242 children (6-8 years) with current AD from the Children's HEalth and Environmental Research study, a 4-year prospective follow-up study with 2-year survey intervals. Latent class analysis was used. Serum IL-13 and thymic stromal lymphopoietin (TSLP) levels at the time of enrollment were measured using ELISA.

RESULTS

We identified four current AD phenotypes in children, characterized as 'early onset with low atopy' (26.4% of the sample; group 1), 'early onset with high atopy and high eosinophil percentages' (48.3%; group 2), 'late onset with low atopy' (9.9%; group 3), and 'late onset with high atopy and normal eosinophils' (15.3%; group 4). Although groups 2 and 4 demonstrated high atopic burden, children in group 2 showed the persistence of AD and eosinophilia associated with a high prevalence of new cases of bronchial hyper-responsiveness and asthma symptoms during follow-up. The serum IL-13 level was significantly increased in the early-onset AD groups, but there was no significant difference in the serum TSLP levels across all four groups.

CONCLUSION

An allergic march-associated AD phenotype exists that is characterized by early onset of AD with its persistence, increased serum IL-13 levels, high atopy, and a persistently increased blood eosinophil percentage.

The specific activation of TRPC4 by Gi protein subtype

The classical type of transient receptor potential channel (TRPC) is a molecular candidate for Ca(2+)-permeable cation channels in mammalian cells. Especially, TRPC4 has the similar properties to Ca(2+)-permeable nonselective cation channels (NSCCs) activated by muscarinic stimulation in visceral smooth muscles. In visceral smooth muscles, NSCCs activated by muscarinic stimulation were blocked by anti-Galphai/o antibodies. However, there is still no report which Galpha proteins are involved in the activation process of TRPC4. Among Galpha proteins, only Galphai protein can activate TRPC4 channel. The activation effect of Galphai was specific for TRPC4 because Galphai has no activation effect on TRPC5, TRPC6 and TRPV6. Coexpression with muscarinic receptor M2 induced TRPC4 current activation by muscarinic stimulation with carbachol, which was inhibited by pertussis toxin. These results suggest that Galphai is involved specifically in the activation of TRPC4.

Involvement of Na(+)-leak channel in substance P-induced depolarization of pacemaking activity in interstitial cells of Cajal

Interstitial cells of Cajal (ICCs) are the pacemaking cells in the gastrointestinal muscles that generate the rhythmic oscillations in membrane potential known as slow waves. ICCs also mediate or transduce inputs from the enteric nervous system. Substance P (SubP) is a member of the family of mammalian tachykinin peptides that are predominantly released by enteric neurons. This study assessed the relationship of Na(+)-leak channel (NALCN) in the SubP-induced depolarization in pacemaking activity in the gastrointestinal tract. The patch-clamp technique for whole-cell recording was used in cultured cluster and single ICCs. Electrophysiological and pharmacological properties of SubP in ICC pacemaking activity were similar to those of NALCN. Reverse-transcription polymerase chain reaction, Western blotting, and immunohistochemistry all showed abundant and localized expression of NALCN messenger RNA and protein in mouse small intestine. NALCN is involved in the SubP-induced depolarization of intestinal pacemaking activity. The protein is a potential target for pharmacological treatment of motor disorders of the gut.

Air pollution interacts with past episodes of bronchiolitis in the development of asthma

BACKGROUND

Exposure to ambient air pollution and bronchiolitis are risk factors for asthma. The aim of this study was to investigate the effect of air pollution on the development of asthma in children with past episodes of bronchiolitis.

METHODS

A prospective 2-year follow-up survey consisting of parental responses to the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire, and allergy evaluations were conducted in 1743 children with a mean age of 6.8 years. Recent 5-year exposure to air pollution was estimated using a geographic information system.

RESULTS

Higher exposure to ozone was associated with airway hyper-responsiveness (PC20  ≤ 16 mg/ml) at enrollment (odds ratio [OR] = 1.60, 95% CI [confidence interval] = 1.13-2.27) and with new episodes of wheezing during the 2-year period (OR = 1.92, 95% CI = 0.96-3.83). Past episodes of bronchiolitis were associated with both current wheezing and physician-diagnosed asthma. When the two factors were combined, the prevalence of bronchial hyper-reactivity (OR = 2.96, 95% CI = 1.41-6.24) and new wheezing (OR = 4.17, 95% CI = 0.89-19.66) as well as current wheezing and physician-diagnosed asthma was even greater (P for trend <0.05 for all). In children with both risk factors, lung function was significantly decreased, with atopic children being particularly vulnerable.

CONCLUSION

In children, the interaction between air pollution and past episodes of bronchiolitis resulted in a greater prevalence of asthma and pointed to an association with bronchial hyper-reactivity and decreased lung function. These results suggest mechanisms underlying the development of asthma.

The relationship of TRP channels to the pacemaker activity of interstitial cells of Cajal in the gastrointestinal tract

Interstitial cells of Cajal (ICCs) are a fundamental component of the pacemaker apparatus of the gastrointestinal (GI) tract. They have special properties that make them unique in their ability to generate and propagate slow waves in gastrointestinal smooth muscle. The pacemaker current that generates slow waves is initially due to a voltage-independent, Ca(2+)-inhibited, non-selective cationic conductance in ICC. The classical transient receptor potential (TRPC) channel 4 was suggested as a molecular candidate for the nonselective cation channel (NSCC) responsible for the pacemaker activity. We have shown that TRPC4-/- mice display normal slow waves and suggest that TRPC4 might be an essential component of the NSCC activated by muscarinic stimulation. Finally, we suggest that TRPM7 is the molecular candidate for the NSCC responsible for pacemaker activity in ICCs on the basis of electrophysiological, molecular biological, and immunohistochemical experiments.

Involvement of phosphatidylinositol 4,5-bisphosphate in the desensitization of canonical transient receptor potential 5

The classic transient receptor potential channel (TRPC) is a candidate for Ca(2+)-permeable cation channel in mammalian cells. TRPC5 is desensitized rapidly after activation by G protein-coupled receptor. Here we investigate the mechanisms of desensitization of TRPC5 using patch-clamp recording. TRPC5 was initially activated by muscarinic stimulation using 50 microM carbachol (CCh) and decayed rapidly in the presence of CCh (desensitization). Intracellularly-applied phosphatidylinositol 4,5-bisphosphate (PIP(2)) slowed the rate of desensitization. In contrast, several other phosphoinositides, including PI(3,4)P(2), PI(3,5)P(2), PI(3,4,5)P(3) and PI(4)P, had no effect on the desensitization of the TRPC5 current. This indicates that PIP(2) attenuates the desensitization of the TRPC5 current in a highly selective manner. Neither wortmannin, an inhibitor of phosphatidylinositol 4-kinase, or poly-L-lysine (PLL), a scavenger of PIP(2), had any effect on desensitization of the TRPC5 current. PIP(2) breakdown appears to be a required step in the desensitization of TRPC5 current, but PIP(2) depletion alone was insufficient for channel desensitization. TRPC5 was inhibited by cytochalasin D treatment. In mouse ileal myocytes, the desensitization of CCh-activated inward current (I(CCh)) also slowed in the presence of PIP(2) in recording pipettes. These results indicate that PIP(2) is involved in the desensitization of TRPC5 currents.

Molecular determinants of PKA-dependent inhibition of TRPC5 channel

Canonical transient receptor potential (TRPC) channels are Ca(2+)-permeable, nonselective cation channels that are widely expressed in numerous cell types. Here, we demonstrate a new mechanism of TPRC isofom 5 (TRPC5) regulation, via cAMP signaling via Gα(s). Monovalent cation currents in human embryonic kidney-293 cells transfected with TRPC5 were induced by G protein activation with intracellular perfusion of GTPγS or by muscarinic stimulation. This current could be inhibited by a membrane-permeable analog of cAMP, 8-bromo-cAMP, by isoproterenol, by a constitutively active form of Gα(s) [Gα(s) (Q227L)], and by forskolin. These inhibitory effects were blocked by the protein kinase A (PKA) inhibitors, KT-5720 and H-89, as well as by two point mutations at consensus PKA phosphorylation sites on TRPC5 (S794A and S796A). Surface expression of several mutated versions of TRPC5, quantified using surface biotinylation, were not affected by Gα(s) (Q227L), suggesting that trafficking of this channel does not underlie the regulation we report. This mechanism of inhibition was also found to be important for the closely related channel, TRPC4, in particular for TRPC4α, although TRPC4β was also affected. However, this form of regulation was not found to be involved in TRPC6 and transient receptor potential vanilloid 6 function. In murine intestinal smooth muscle cells, muscarinic stimulation-induced cation currents were mediated by TRPC4 (>80%) and TRPC6. In murine intestinal smooth muscle cells, 8-bromo-cAMP, adrenaline, and isoproterenol decreased nonselective cation currents activated by muscarinic stimulation or GTPγS. Together, these results suggest that TRPC5 is directly phosphorylated by G(s)/cAMP/PKA at positions S794 and S796. This mechanism may be physiologically important in visceral tissues, where muscarinic receptor and β(2)-adrenergic receptor are involved in the relaxation and contraction of smooth muscles.

The Success of Thread-embedding Therapy in Generating Hair Re-growth in Mice Points to Its Possibly Having a Similar Effect in Humans

OBJECTIVES

Recently, thread-embedding therapy (TET) has been widely applied in Korean medicine for cosmetic purposes such as reducing skin wrinkles. An inserted thread was reported to have induced continuous stimulation, followed by support for connective tissue regeneration. However, the potential role of TET in hairgrowth has not yet been reported.

METHODS

We designed this study to evaluate whether TET has a hair-growth-promoting effect. C57 black 6 (C57BL/6) mice were divided into three groups: normal saline-treated, minoxidil-treated, and thread-embedded groups. Normal saline or 5% minoxidil was topically sprayed on the dorsal skin of the mice once a day for 16 days. Medical threads were embedded into the dorsal skin of the mice in a single application. Hair growth activity was evaluated by using dermoscopic and microscopic observations. Sections of the dorsal skin were stained with hematoxylin and eosin. Expressions of bromodeoxyuridine (BrdU), proliferating cell nuclear antigen (PCNA), fibroblast growth factor-7 (FGF-7), and fibroblast growth factor-5 (FGF-5) were detected by using immunohistochemical staining. A reverse transcription-polymerase chain reaction (RT-PCR) analysis was adopted to measure the messenger RNA (mRNA) expressions of FGF-7 and FGF-5.

RESULTS

TET enhanced anagen development in the hair follicles of C57BL/6 mice. The expressions of BrdU and PCNA, both of which imply active cellular proliferation, were increased by using TET. Moreover, TET increased the expression of FGF-7, an anagen-inducing growth factor, while decreasing the expression of FGF-5, an anagen-cessation growth factor, both at the protein and the mRNA levels.

CONCLUSION

TET enhanced hair re-growth in C57BL/6 mice. TET regulated the expressions of anagen-associated growth factors and activated the proliferation of hair follicular cells in depilated skin lesions. Considering its long-lasting effect, TET may be a good alternative therapeutic for the treatment of alopecia.

Identification of TRPM7 channels in human intestinal interstitial cells of Cajal

AIM

To investigate the characteristics of slow electrical waves and the presence of transient receptor potential melastatin-type 7 (TRPM7) in the human gastrointestinal (GI) tract.

METHODS

Conventional microelectrode techniques were used to record intracellular electrical responses from human GI smooth muscle tissue. Immunohistochemistry was used to identify TRPM7 channels in interstitial cells of Cajal (ICCs).

RESULTS

The human GI tract generated slow electrical waves and had ICCs which functioned as pacemaker cells. Flufenamic acid, a nonselective cation channel blocker, and 2-APB (2-aminoethoxydiphenyl borate) and La(3+), TRPM7 channel blockers, inhibited the slow waves. Also, TRPM7 channels were expressed in ICCs in human tissue.

CONCLUSION

These results suggest that the human GI tract generates slow waves and that TRPM7 channels expressed in the ICCs may be involved in the generation of the slow waves.