Screening of environmental stimuli for the positive regulation of stomatal aperture in centipedegrass.

Grasslands, the largest carbon pool in China, possess enormous potential for carbon sequestration. Increasing the stomatal aperture to increase the CO2 absorption capacity is a potential method to improve plant photosynthetic efficiency and ultimately enhance the carbon sequestration capacity of grass plants. Research on stomatal aperture regulation has focused mostly on Arabidopsis or crops, while research on grass plants in these areas is scarce, which seriously restricts the implementation of this grassland carbon sequestration strategy. Here, a widely used ecological grass, centipedegrass, was used as the experimental material. First, a convenient method for observing the stomatal aperture was developed. The leaves were floated in a potassium ion-containing open solution (67 mM KCl, pH 6.0) with the adaxial surface rather than the abaxial surface in contact with the solution and were cultivated under light for 1.5 h. Then, nail polish was applied on the adaxial surface, and a large number of open stomata were imprinted. Second, with the help of this improved method, the concentration‒response characteristics of the stomatal aperture to eleven environmental stimuli were tested. The stomatal aperture is dependent on these environmental stimuli in a concentration-dependent manner. The addition of 100 µM brassinolide led to the maximal stomatal aperture. This study provided a technical basis for manipulating stomatal opening to increase the carbon sequestration capacity of centipedegrass.

[Retracted] miR­206 inhibits cancer initiating cells by targeting EHF in gastric cancer.

Following the publication of this paper, it was drawn to the Editor's attention by a concerned reader that the colony formation assay data shown in Figs. 2, 4 and 8 were strikingly similar to data that had already appeared in another article written by different authors at different research institutes [Chen W, Wang J, Liu S, Wang S, Cheng Y, Zhou W, Duan C and Zhang C: MicroRNA­361­3p suppresses tumor cell proliferation and metastasis by directly targeting SH2B1 in NSCLC. J Exp Clin Cancer Res 35: 76, 732516, 2016]. Owing to the fact that the contentious data in the above article had already been published prior to its submission to Oncology Reports, the Editor has decided that this paper should be retracted from the Journal. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive a reply. The Editor apologizes to the readership for any inconvenience caused. [Oncology Reports 38: 1688­1694, 2017; DOI: 10.3892/or.2017.5794].

An appropriate ammonium: nitrate ratio promotes the growth of centipedegrass: insight from physiological and micromorphological analyses.

Reasonable nitrogen fertilizer application is an important strategy to maintain optimal growth of grasslands, thereby enabling them to better fulfil their ecological functions while reducing environmental pollution caused by high nitrogen fertilizer production and application. Optimizing the ammonium (NH4 +):nitrate (NO3 -) ratio is a common approach for growth promotion in crops and vegetables, but research on this topic in grass plants has not received sufficient attention. Centipedegrass, which is widely used in landscaping and ecological protection, was used as the experimental material. Different NH4 +:NO3 - ratios (0: 100, 25:75, 50:50, 75:25, 100:0) were used as the experimental treatments under hydroponic conditions. By monitoring the physiological and morphological changes under each treatment, the appropriate NH4 +:NO3 - ratio for growth and its underlying mechanism were determined. As the proportion of ammonium increased, the growth showed a "bell-shaped" response, with the maximum biomass and total carbon and nitrogen accumulation achieved with the NH4 +:NO3 - ratio of 50:50 treatment. Compared with the situation where nitrate was supplied alone, increasing the ammonium proportion increased the whole plant biomass by 93.2%, 139.7%, 59.0%, and 30.5%, the whole plant nitrogen accumulation by 44.9%, 94.6%, 32.8%, and 54.8%, and the whole plant carbon accumulation by 90.4%, 139.9%, 58.7%, and 26.6% in order. As a gateway for nitrogen input, the roots treated with an NH4 +:NO3 - ratio of 50:50 exhibited the highest ammonium and nitrate uptake rate, which may be related to the maximum total root length, root surface area, average root diameter, root volume, and largest root xylem vessel. As a gateway for carbon input, leaves treated with an NH4 +:NO3 - ratio of 50:50 exhibited the highest stomatal aperture, stomatal conductance, photosynthetic rate, transpiration rate, and photosynthetic products. The NH4 +:NO3 - ratio of 50:50 treatment had the largest stem xylem vessel area. This structure and force caused by transpiration may synergistically facilitate root-to-shoot nutrient translocation. Notably, the change in stomatal opening occurred in the early stage (4 hours) of the NH4 +:NO3 - ratio treatments, indicating that stomates are structures that are involved in the response to changes in the root NH4 +:NO3 - ratio. In summary, we recommend 50:50 as the appropriate NH4 +:NO3 - ratio for the growth of centipedegrass, which not only improves the nitrogen use efficiency but also enhances the carbon sequestration capacity.

Twenty-four-hour real-time continuous monitoring of acute focal cerebral ischemia in rabbits based on magnetic inductive phase shift.

BACKGROUND: As a serious clinical disease, ischemic stroke is usually detected through magnetic resonance imaging and computed tomography. In this study, a noninvasive, non-contact, real-time continuous monitoring system was constructed on the basis of magnetic induction phase shift (MIPS) technology. The "thrombin induction method", which conformed to the clinical pathological development process of ischemic stroke, was used to construct an acute focal cerebral ischemia model of rabbits. In the MIPS measurement, a "symmetric cancellation-type" magnetic induction sensor was used to improve the sensitivity and antijamming capability of phase detection. METHODS: A 24-h MIPS monitoring experiment was carried out on 15 rabbits (10 in the experimental group and five in the control group). Brain tissues were taken from seven rabbits for the 2% triphenyl tetrazolium chloride staining and verification of the animal model. RESULTS: The nonparametric independent-sample Wilcoxon rank sum test showed significant differences (p < 0.05) between the experimental group and the control group in MIPS. Results showed that the rabbit MIPS presented a declining trend at first and then an increasing trend in the experimental group, which may reflect the pathological development process of cerebral ischemic stroke. Moreover, TTC staining results showed that the focal cerebral infarction area increased with the development of time CONCLUSIONS: Our experimental study indicated that the MIPS technology has a potential ability of differentiating the development process of cytotoxic edema from that of vasogenic edema, both of which are caused by cerebral ischemia.

Significance of neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, lymphocyte-to-monocyte ratio and prognostic nutritional index for predicting clinical outcomes in T1-2 rectal cancer.

BACKGROUND: Inflammation-related parameters have been revealed to have prognostic value in multiple caners. However, the significance of some inflammation-related parameters, including the peripheral blood neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR) and prognostic nutritional index (PNI), remains controversial in T1-2 rectal cancer (RC). METHODS: Clinical data of 154 T1-2 RC patients were retrospectively reviewed. The cut-off values for NLR, PLR, LMR, and PNI were determined by receiver operating characteristic curves. The relationships of these parameters with postoperative morbidities and prognosis were statistically analysed. RESULTS: The optimal cut-off values for preoperative NLR, PLR, LMR and PNI were 2.8, 140.0, 3.9, and 47.1, respectively. Significant but heterogeneous associations were found between NLR, PLR, LMR and PNI and clinicopathological factors. In addition, high NLR, high PLR, and low PNI were correlated with an increased postoperative morbidity rate. Patients with high NLR/PLR or low LMR/PNI had lower OS and DFS rates. On multivariate analysis, only high NLR was identified as an independent risk factor for poor DFS. CONCLUSIONS: NLR, PLR, and PNI are valuable factors for predicting postoperative complications in T1-2 RC patients. A preoperative NLR of more than 2.8 is an independent prognostic factor for poor DFS in T1-2 RC patients.

Synthesis and anti-proliferative activity of allogibberic acid derivatives containing 1,2,3-triazole pharmacophore.

Sixty novel allogibberic acid derivatives containing 1,2,3-triazole pharmacophore were designed and synthesized. The key chemical processes include aromatization of the A ring in gibberellins, formation of allogibberic azides and its copper mediated Huisgen 1,3-dipolar cycloaddition with alkynes. A number of hybrids containing α,ß-unsaturated ketone moiety exhibited excellent in vitro cytotoxic activities. Some of the hybrids were more selective to MCF-7 and SW480 cell lines with IC50 values at least 8-fold more cytotoxic than cisplatin (DDP). The most potent compounds C43 and C45 are more cytotoxic than cisplatin (DDP) against all tested five tumor cell lines, with IC50 values of 0.25-1.72 µM. Mechanism of action studies indicated that allogibberic-triazole derivative C45 could induce the S phase cell cycle arrest and apoptosis in SMMC-7721 cell lines.

Circulating SH2B1 is associated with an increased risk of gastric cancer.

Gastric cancer (GC) is one of the most common types of cancer in humans and the second leading cause of cancer-associated mortality worldwide. Identifying novel risk factors will facilitate the development of therapeutic strategies to prevent and treat GC. Increased expression of the Src homology 2 B adaptor protein 1 (SH2B1) may stimulate the malignant progression of lung cancer, esophageal cancer and neuroblastoma. However, its function in GC has not yet been investigated. To identify whether increased serum SH2B1 is a risk factor for GC, the present study performed a nested case-control study of patients within the Chinese cohort study. Levels of serum SH2B1 were measured in 563 patients diagnosed with GC during the follow-up period and in 1,126 matched healthy controls. The results demonstrated that high levels of serum SH2B1 were associated with an increased GC risk (odds ratio, 3.23; 95% confidence interval, 2.45-5.65). When analyses were stratified further by sex, age and smoking, an association between increased levels of SH2B1 and GC was identified in males but not in females. Furthermore, the association between SH2B1 levels and GC was more evident in younger than in older participants, and statistically significant in current smokers but not in nonsmokers. These results were not altered following the exclusion of outliers. Furthermore, it was demonstrated that overexpression of SH2B1 contributes to the malignant transformation of normal gastric epithelial cells. Thus, the present study demonstrated that elevated serum SH2B1 levels may increase the risk of GC.

miR­206 inhibits cancer initiating cells by targeting EHF in gastric cancer.

Cancer initiating cells (CIC) are defined as the unique subpopulation in the tumors that possess the ability to initiate tumor growth and sustain self-renewal as well as metastatic potential. In this study, we found that EHF overexpression promoted formation of CIC traits and silencing it inhibited the traits in gastric cancer NCI­N87 cells. Overexpressing EHF downregulated the antitumor effect of 5-fluorouracil (5-FU) in NCI­N87 cells. We found that miR­206 downregulated EHF protein expression by targeting its 3'UTR in NCI­N87 cells and GES-1 cells. Overexpressing miR­206 inhibited formation of CIC in NCI­N87 cells. In gastric cancer tissues, EHF protein expression was upregulated and miR­206 was downregulated. We identified a negative correlation between EHF protein and miR­206 expression in gastric cancer tissues. Thus, we concluded that miR­206 inhibits formation of CICs by targeting EHF in gastric cancer.

miR-874 inhibits metastasis-relevant traits via targeting SH2B adaptor protein 1 (SH2B1) in gastric cancer.

Gastric cancer (GC) is one of the most common human cancers and the second leading cause of cancer-related mortality worldwide. The major cause of death is metastasis. Elucidating molecular mechanism of metastasis in gastric cancer will help us to further understand the pathogenesis and progression of the disease, and offer new targets for effective therapies. In this study, we found that SH2B1 overexpression promoted invasion, migration and anoilds resistance and silencing it inhibited invasion, migration and anoilds resistance in gastric cancer SGC-7901 cells. However, over-expressing or silencing it did not affect proliferation in the cells. miR-874 could degrade SH2B1 by targeting its 3'UTR and was negatively associated with metastasis traits in SGC-7901 cells. Its overexpression inhibited proliferation in the cells. Thus, we concluded that miR-874 inhibits metastasis-relevant traits via targeting SH2B1 in gastric cancer SGC-7901 cells.

MicroRNA-17 induces epithelial-mesenchymal transition consistent with the cancer stem cell phenotype by regulating CYP7B1 expression in colon cancer.

MicroRNA-17 (miRNA-17/miR­17) expression has been confirmed to be significantly higher in colorectal cancer tissues than in normal tissues. However, its exact role in colorectal cancer has not yet been fully elucidated. In this study, we found that miR-17 not only promoted epithelial-mesenchymal transition (EMT), but also promoted the formation of a stem cell-like population in colon cancer DLD1 cells. We also wished to determine the role of cytochrome P450, family 7, subfamily B, polypeptide 1 (CYP7B1) in CRC. miR-17 was overexpressed using a recombinant plasmid and CYP7B1 was silenced by transfection with shRNA. Western blot analysis was used to determine protein expression in the DLD1 cells and in tumor tissues obtained from patients with colon cancer. Our results revealed that miR­17 overexpression led to the degradation of CYP7B1 mRNA expression in DLD1 cells. In addition, we found that the silencing of CYB7B1 promoted EMT and the formation of a stem cell-like population in the cells. Thus, our findings demonstrate that miR­17 induces EMT consistent with the cancer stem cell phenotype by regulating CYP7B1 expression in colon cancer.

Gibberellin derivative GA-13315 sensitizes multidrug-resistant cancer cells by antagonizing ABCB1 while agonizes ABCC1.

PURPOSE: GA-13315 is a gibberellin derivative that reveals antitumor and antineoplastic effects both in vitro and in vivo. In the present study, the chemosensitizing effects of GA-13315 in multidrug-resistant cell lines were examined and the underlying mechanisms were investigated. METHODS: Cytotoxicity and chemosensitizing effects of GA-13315 were determined by MTT assay. Function of ABC transporter was analyzed by measuring intracellular drug accumulation of doxorubicin and rhodamine 123 and by determining the ATPase activity of ABC transporter. Expression levels of apoptosis regulators were analyzed using real-time quantitative PCR and Western blot. RESULTS: GA-13315 selectively killed MCF-7/adr cells that overexpress P-glycoprotein (ABCB1) over the parent MCF-7 cells. In combination with conventional chemotherapeutic agents, GA-13315 at sub-toxic concentrations reversed the multidrug resistance mediated by ABCB1 but exacerbated the resistance conferred by multidrug resistance-associated protein 1 (ABCC1). GA-13315 increased intracellular accumulation of doxorubicin and rhodamine 123 in MCF-7/adr cells and in ABCB1-transfected HEK293 cells but facilitated drug flush-out from cells that overexpress ABCC1. GA-13315 inhibited the ATPase activity of ABCB1 while stimulated that of ABCC1. Moreover, the downregulated expression of Bax in MCF-7/adr cells was restored by GA-13315 markedly. CONCLUSION: These data suggest that GA-13315 sensitizes multidrug-resistant cells at least partially by impeding the efflux function of ABCB1. The upregulation of Bax by GA-13315 may also contribute to the sensitizing action. The opposite effects of GA-13315 on different ATP-binding cassette transporters and their implications in overcoming drug resistance require further investigation.

The Classification of Tongue Colors with Standardized Acquisition and ICC Profile Correction in Traditional Chinese Medicine.

Background and Goal. The application of digital image processing techniques and machine learning methods in tongue image classification in Traditional Chinese Medicine (TCM) has been widely studied nowadays. However, it is difficult for the outcomes to generalize because of lack of color reproducibility and image standardization. Our study aims at the exploration of tongue colors classification with a standardized tongue image acquisition process and color correction. Methods. Three traditional Chinese medical experts are chosen to identify the selected tongue pictures taken by the TDA-1 tongue imaging device in TIFF format through ICC profile correction. Then we compare the mean value of L*a*b* of different tongue colors and evaluate the effect of the tongue color classification by machine learning methods. Results. The L*a*b* values of the five tongue colors are statistically different. Random forest method has a better performance than SVM in classification. SMOTE algorithm can increase classification accuracy by solving the imbalance of the varied color samples. Conclusions. At the premise of standardized tongue acquisition and color reproduction, preliminary objectification of tongue color classification in Traditional Chinese Medicine (TCM) is feasible.

Inclusion complex of GA-13316 with ß-cyclodextrin: preparation, characterization, molecular modeling, and in vitro evaluation.

The inclusion complex of GA-13316 with ß-cyclodextrin (ß-CD) is one of a unique series of gibberellin derivatives possessed of potential anticancer activities. The complex with ß-CD was characterized by means of UV, XRD, DSC, TG, (1)H, and 2D NMR spectroscopy. In addition, we investigated the main aspects of the interaction between GA-13316 and ß-CD using both experimental and molecular modeling approaches. The complex still maintained its anticancer activity, as shown by in vitro cell survival assay on the human colon carcinoma cell line (HCT116) and the human lung cancer cell line (H460). The results showed that the use of ß-CD could be obviously improved the water solubility and stability of GA-13316, implying that the inclusion complex could be a promising future therapeutic agent.

Coexpression of recombinant adenovirus carrying GDNF and EDNRB genes in neural stem cells in vitro.

Gene therapy and nerve stem cells isolated from the developing human enteric nervous system (ENS) are significant. They may open the route for the cell therapy of Hirschsprung's disease (HD). We have constructed the recombinant adenovirus-carrying glial cell line-derived neurotrophic factor (GDNF) and endothelin receptor B (EDNRB) gene, and investigated the exosomatic coexpression in neural stem cells. The recombinant adenovirus Ad-GE coexpressing GDNF and EDNRB gene was constructed by the AdEasy system and confirmed by the reverse transcription polymerase chain reaction (RT-PCR) method. Expression of exogenous genes in neural stem cells after transfection was confirmed by the flow cytometry and real-time fluorescence quantitative PCR. Fragments of pAd Track-CMV-GE were consistent with GDNF and EDNRB. The green fluorescence of the positive cells was followed by fluorescence microscopy at 24 h after NSCs had been transfected, reaching a peak at 72 h after transfection. Flow cytometry showed that the efficiency of transfection was 15.0, 23.6, and 25.4% at 24, 48 and 72 h respectively. Real-time fluorescence quantitative PCR showed the expression levels of mRNA of GDNF and EDNRB in 48 and 72 h groups were obviously higher than that in 24 and 96 h groups. Recombinant adenovirus carrying GDNF and EDNRB genes are coexpressed in neural stem cells, which may offer the possibility of a novel approach to local combination gene therapy for Hirschsprung's disease.

[Effects of quercetin on nuclear factor-κB p65 expression in renal ubiquitin-proteasome system of diabetic rats].

OBJECTIVE: To investigate the protective effect of quercetin on diabetic nephropathy and to explore its possible mechanism. METHODS: Type 2 diabetes mellitus rat model was established by feeding high-carbohydrate-fat diet and injecting with streptozotocin. At 72 hour after injection, blood samples were collected from the tail veins of all rats. Those rats with blood glucose level ≥ 16.7 mmol/L were considered as the diabetes model been successfully established. The model rats were randomly divided into type 2 diabetic group (group DM, n = 9) and quercetin group (group QUE, n = 9). Other rats were used as normal controls (group NC, n = 8). All rats were performed by intragastric administration for 8 weeks. At the end of experiment, the rats were sacrificed and fasting plasma glucose (FPG), fasting insulin(FIns), serum creatinine (SCr), blood urea nitrogen (BUN), TG, TC, LDL-C, 24 h urine protein (24 h UP), and kidney index (KI) were evaluated. Pathological changes of kidney were observed by periodic acid-silver methenamine (PASM). The expressions of ubiquitin and NF-κB p65 on glomeruli were examined by immunohistochemical method, and its association with the incidence of proteinuria was analyzed. RESULTS: In groups DM and QUE, the level of FPG [(25.45 ± 1.23) mmol/L and (19.99 ± 1.20) mmol/L], FIns [(25.67 ± 2.58) mU/L and (19.29 ± 1.80) mU/L], SCr [(44.00 ± 2.53) µmol/L and (34.43 ± 2.23) µmol/L], BUN[(11.60 ± 0.39) mmol/L and (8.20 ± 0.37) mmol/L], TG[(3.32 ± 0.22)mmol/L and (2.43 ± 0.25) mmol/L], TC [(2.95 ± 0.21) mmol/L and (2.24 ± 0.17) mmol/L], LDL-C [(2.03 ± 0.22) mmol/L and (1.49 ± 0.13) mmol/L], 24 h UP[(46.67 ± 2.50) mg/24 h and (25.57 ± 2.82) mg/24 h] and KI [(9.76 ± 0.30)×10³ and (8.44 ± 0.26)×10³] were significantly increased than the indexes of group NC [(6.56 ± 0.41) mmol/L, (12.63 ± 1.41) mU/L, (22.88 ± 2.36) µmol/L, (5.45 ± 0.51) mmol/L, (1.64 ± 0.11) mmol/L, (1.33 ± 0.17) mmol/L, (0.46 ± 0.05) mmol/L, (12.38 ± 1.19)/24 h and (6.78 ± 0.12)×10³]. Moreover, the above indexes in group QUE were obviously lower than group DM. There was evidence of pathological changes associated with diabetes, such as focal and segmental sclerosis and thickened basement and mesangial expansion. The expressions of ubiquitin and NF-κB p65 in renal tissues of group DM increased significantly (P < 0.01). The expression of ubiquitin and NF-κB p65 were positively related with the level of 24 h UP (r = 0.893, 0.879, P < 0.01). Compared with group DM, all above indexes in group QUE were markedly alleviated (P < 0.01). The expression of ubiquitin and NF-κB p65 was reduced but didn't reach level in group NC (P < 0.01). CONCLUSION: The increased expression of NF-κB induced by ubiquitin-proteasome system may participate in the pathogenesis of proteinuria in diabetic nephropathy. Quercetin has renal protective effects partly through reducing NF-κB p65 expression.

Adenosine-5'-triphosphate up-regulates proliferation of human cardiac fibroblasts.

BACKGROUND AND PURPOSE: ATP is a potent signalling molecule that regulates biological activities including increasing or decreasing proliferation in different types of cells. The aim of the present study was to investigate how ATP regulates the proliferation of human cardiac fibroblasts. EXPERIMENTAL APPROACH: Reverse transcription (RT)-PCR, Western blot analysis, cell proliferation and migration assays were employed to investigate the effects of ATP on human adult ventricular fibroblasts. KEY RESULTS: ATP increased cell proliferation in a concentration-dependent manner. Similarly, the P2X receptor agonist α,ß-methylene ATP and P2Y receptor agonist ATP-γS also up-regulated cell proliferation. The P2 receptor antagonists suramin and reactive blue-2 prevented the ATP-induced increase in proliferation and RT-PCR and Western blot analysis revealed that mRNAs of P2X(4/7) and P2Y(2) are abundant in cardiac fibroblasts. ATP increased phosphorylated PKB (Akt) and ERK1/2 levels; an effect antagonized by suramin, reactive blue-2, the PI3-kinase inhibitor, wortmannin, PKB inhibitor, API-2, and MAPK inhibitor, PD98059. These kinase inhibitors also prevented the ATP-induced increase in proliferation. In addition, ATP enhanced the progression of cells from the G0/G1 phase to the S phase by increasing the expression of proteins for cyclin D1 and cyclin E. Silencing the P2X(4/7) and P2Y(2) receptors with siRNA targeting the corresponding receptor diminished ATP-stimulated proliferation and migration of the cardiac fibroblasts. CONCLUSION AND IMPLICATION: ATP activates P2X(4/7) and P2Y(2) receptors and up-regulates the proliferation of human cardiac fibroblasts by promoting cell cycling progression. It also increases the migration of these cells. These effects of ATP may be involved in cardiac remodelling of injured hearts.

Inclusion complex of GA-13315 with cyclodextrins: preparation, characterization, inclusion mode and properties.

GA-13315 (13-chlorine-3,15-dioxy-gibberllic acid methyl ester) was semi-synthesized by GA3 (gibberellic acid) as a potential anticancer drug. To pursue its promising application, cyclodextrin was used for forming complexes to overcome its drawbacks such as poor water solubility and stability. So, GA-13315/CD complexes were prepared with native ß-cyclodextrin and its derivatives (hydroxypropyl-ß-cyclodextrin (HPßCD)) and their inclusion complexation behavior, characterization and binding ability in both solution and the solid state was studied by means of UV, XRD, DSC, SEM, (1)H and 2D NMR spectroscopy. Furthermore, preliminary in vitro cytotoxicity assay showed that the complexes still maintain antitumor activities, compared with GA-13315 or adriamycin (ADM, positive control) as the positive control. The results showed that the water solubility and stability of GA-13315 were obviously improved in the inclusion complex with cyclodextrins, suggesting the inclusion complexes as promising future therapeutic agents.

Multiple Ca2+ signaling pathways regulate intracellular Ca2+ activity in human cardiac fibroblasts.

Ca(2+) signaling pathways are well studied in cardiac myocytes, but not in cardiac fibroblasts. The aim of the present study is to characterize Ca(2+) signaling pathways in cultured human cardiac fibroblasts using confocal scanning microscope and RT-PCR techniques. It was found that spontaneous intracellular Ca(2+) (Ca(i) (2+)) oscillations were present in about 29% of human cardiac fibroblasts, and the number of cells with Ca(i) (2+) oscillations was increased to 57.3% by application of 3% fetal bovine serum. Ca(i) (2+) oscillations were dependent on Ca(2+) entry. Ca(i) (2+) oscillations were abolished by the store-operated Ca(2+) (SOC) entry channel blocker La(3+), the phospholipase C inhibitor U-73122, and the inositol trisphosphate receptors (IP3Rs) inhibitor 2-aminoethoxydiphenyl borate, but not by ryanodine. The IP3R agonist thimerosal enhanced Ca(i) (2+) oscillations. Inhibition of plasma membrane Ca(2+) pump (PMCA) and Na(+)-Ca(2+) exchanger (NCX) also suppressed Ca(i) (2+) oscillations. In addition, the frequency of Ca(i) (2+) oscillations was reduced by nifedipine, and increased by Bay K8644 in cells with spontaneous Ca(2+) oscillations. RT-PCR revealed that mRNAs for IP3R1-3, SERCA1-3, Ca(V)1.2, NCX3, PMCA1,3,4, TRPC1,3,4,6, STIM1, and Orai1-3, were readily detectable, but not RyRs. Our results demonstrate for the first time that spontaneous Ca(i) (2+) oscillations are present in cultured human cardiac fibroblasts and are regulated by multiple Ca(2+) pathways, which are not identical to those of the well-studied contractile cardiomyocytes. This study provides a base for future investigations into how Ca(2+) signals regulate biological activity in human cardiac fibroblasts and cardiac remodeling under pathological conditions.

Characterization of multiple ion channels in cultured human cardiac fibroblasts.

BACKGROUND: Although fibroblast-to-myocyte electrical coupling is experimentally suggested, electrophysiology of cardiac fibroblasts is not as well established as contractile cardiac myocytes. The present study was therefore designed to characterize ion channels in cultured human cardiac fibroblasts. METHODS AND FINDINGS: A whole-cell patch voltage clamp technique and RT-PCR were employed to determine ion channels expression and their molecular identities. We found that multiple ion channels were heterogeneously expressed in human cardiac fibroblasts. These include a big conductance Ca(2+)-activated K(+) current (BK(Ca)) in most (88%) human cardiac fibroblasts, a delayed rectifier K(+) current (IK(DR)) and a transient outward K(+) current (I(to)) in a small population (15 and 14%, respectively) of cells, an inwardly-rectifying K(+) current (I(Kir)) in 24% of cells, and a chloride current (I(Cl)) in 7% of cells under isotonic conditions. In addition, two types of voltage-gated Na(+) currents (I(Na)) with distinct properties were present in most (61%) human cardiac fibroblasts. One was a slowly inactivated current with a persistent component, sensitive to tetrodotoxin (TTX) inhibition (I(Na.TTX), IC(50) = 7.8 nM), the other was a rapidly inactivated current, relatively resistant to TTX (I(Na.TTXR), IC(50) = 1.8 microM). RT-PCR revealed the molecular identities (mRNAs) of these ion channels in human cardiac fibroblasts, including KCa.1.1 (responsible for BK(Ca)), Kv1.5, Kv1.6 (responsible for IK(DR)), Kv4.2, Kv4.3 (responsible for I(to)), Kir2.1, Kir2.3 (for I(Kir)), Clnc3 (for I(Cl)), Na(V)1.2, Na(V)1.3, Na(V)1.6, Na(V)1.7 (for I(Na.TTX)), and Na(V)1.5 (for I(Na.TTXR)). CONCLUSIONS: These results provide the first information that multiple ion channels are present in cultured human cardiac fibroblasts, and suggest the potential contribution of these ion channels to fibroblast-myocytes electrical coupling.