Discovery of 4-arylthiophene-3-carboxylic acid as inhibitor of ANO1 and its effect as analgesic agent

Anoctamin 1 (ANO1) is a kind of calcium-activated chloride channel involved in nerve depolarization. ANO1 inhibitors display significant analgesic activity by the local peripheral and intrathecal administration. In this study, several thiophenecarboxylic acid and benzoic acid derivatives were identified as novel ANO1 inhibitors through the shape-based virtual screening, among which the 4-arylthiophene-3-carboxylic acid analogues with the best ANO1 inhibitory activity were designed, synthesized and compound

Colonic Transit Disorder Mediated by Downregulation of Interstitial Cells of Cajal/Anoctamin-1 in Dextran Sodium Sulfate-induced Colitis Mice

BACKGROUND/AIMS: Interstitial cells of Cajal (ICC) and their special calcium-activated chloride channel, anoctamin-1 (ANO1) play pivotal roles in regulating colonic transit. This study is designed to investigate the role of ICC and the ANO1 channel in colonic transit disorder in dextran sodium sulfate (DSS)-treated colitis mice. METHODS: Colonic transit experiment, colonic migrating motor complexes (CMMCs), smooth muscle spontaneous contractile experiments, intracellular electrical recordings, western blotting analysis, and quantitative polymerase chain reaction were applied in this study. RESULTS: The mRNA and protein expressions of c-KIT and ANO1 channels were significantly decreased in the colons of DSS-colitis mice. The colonic artificial fecal-pellet transit experiment in vitro was significantly delayed in DSS-colitis mice. The CMMCs and smooth muscle spontaneous contractions were significantly decreased by 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), an ANO1 channel blocker, and NG-Nitro-L-arginine methyl ester hydrochloride (L-NAME), an inhibitor of nitric oxide synthase activity, in DSS-colitis mice compared with that of control mice. Intracellular electrical recordings showed that the amplitude of NPPB-induced hyperpolarization was more positive in DSS-colitis mice. The electric field stimulation-elicited nitric-dependent slow inhibitory junctional potentials were also more positive in DSS-colitis mice than those of control mice. CONCLUSION: The results suggest that colonic transit disorder is mediated via downregulation of the nitric oxide/ICC/ANO1 signalling pathway in DSS-colitis mice.

EF-hand like Region in the N-terminus of Anoctamin 1 Modulates Channel Activity by Ca²⁺ and Voltage

Anoctamin1 (ANO1) also known as TMEM16A is a transmembrane protein that functions as a Ca²⁺ activated chloride channel. Recently, the structure determination of a fungal Nectria haematococca TMEM16 (nhTMEM16) scramblase by X-ray crystallography and a mouse ANO1 by cryo-electron microscopy has provided the insight in molecular architecture underlying phospholipid scrambling and Ca²⁺ binding. Because the Ca²⁺ binding motif is embedded inside channel protein according to defined structure, it is still unclear how intracellular Ca²⁺ moves to its deep binding pocket effectively. Here we show that EF-hand like region containing multiple acidic amino acids at the N-terminus of ANO1 is a putative site regulating the activity of ANO1 by Ca²⁺ and voltage. The EF-hand like region of ANO1 is highly homologous to the canonical EF hand loop in calmodulin that contains acidic residues in key Ca²⁺-coordinating positions in the canonical EF hand. Indeed, deletion and Ala-substituted mutation of this region resulted in a significant reduction in the response to Ca²⁺ and changes in its key biophysical properties evoked by voltage pulses. Furthermore, only ANO1 and ANO2, and not the other TMEM16 isoforms, contain the EF-hand like region and are activated by Ca²⁺. Moreover, the molecular modeling analysis supports that EF-hand like region could play a key role during Ca²⁺ transfer. Therefore, these findings suggest that EF-hand like region in ANO1 coordinates with Ca²⁺ and modulate the activation by Ca²⁺ and voltage.

A review of ANO1-based calcium activated chloride channel modulators / 药学学报

Calcium-activated chloride channel (CaCC) is an anion channel, widely distributed in the human body, taking a part in cell functions including secretion, heart muscle repolarization, nerve signal transmission and several physiological activities. The anoctamin 1 (ANO1) protein is the molecular basis of CaCC and the modification of ANO1 protein will produce a variety of pharmacological effects, such as analgesia, treating dysentery and asthma, even tumor proliferation and migration inhibition. In the past decade, many methods in screening of ANO1 regulators have been developed. Although a series of the ANO1-based CaCC regulatory molecules have been identified, the pharmacological effects of these molecules are not consistent. In this review, we introduce ANO1 protein regulators from many aspects including bio-test methods, structure-activity relationships, and the potential applications.

Highlights for the 6th International Ion Channel Conference: ion channel structure, function, disease and therapeutics

To foster communication and interactions amongst international scholars and scientists in the field of ion channel research, the 6th International Ion Channel Conference (IICC-2017) was held between June 23-27, 2017 in the eastern coastal city of Qingdao, China. The meeting consisted of 450 attendees and 130 speakers and poster presenters. The program consisted of research progress, new findings and ongoing studies that were focused on (1) Ion channel structure and function; (2) Ion channel physiology and human diseases; (3) Ion channels as targets for drug discovery; (4) Technological advances in ion channel research. An insightful overview was presented on the structure and function of the mechanotransduction channelNOMPC (No mechanoreceptor potential C), a member of the transient receptor potential (TRP) channel family. Recent studies on Transmembrane protein 16 or Anoctamin-1 (TMEM16A, a member of the calcium-activated chloride channel [CaCC] family) were summarized as well. In addition, topics for ion channel regulation, homeostatic feedback and brain disorders were thoroughly discussed. The presentations at the IICC-2017 offer new insights into our understanding of ion channel structures and functions, and ion channels as targets for drug discovery.

Effect of Ca2+-activated Chloride Channel Density on Gating Properties of Anoctamin 1 / 中国医科大学学报

Objective To investigate the effect of channel density on the gating properties of Anoctamin 1(Ano1,TMEM16A)Ca2+?activated chlo?ride channel. Methods Ano1 expression plasmids were transiently transfected into HEK293 cells. High density and low density of Ano1 was ob?tained after expressing the protein for 24 h and 6 h,respectively. Electrophysiological recordings were performed in the whole?cell patch clamp con?figuration. The activation kinetics of current traces was fitted by exponentials. Results The current density was significantly higher in cells express?ing Ano1 for 24 h than those expressing Ano1 for 6 h(P0.05). Conclusion Our findings suggested that chan?nel density regulates the gating of Ano1. High channel density promotes activation of Ano1.

Effects of ANO1 on tumorigenesis / 中国病理生理杂志

Anoctamin 1 (ANO1) is a calcium-activated chloride channel and is amplified and over-expressed in gastrointestinal stromal tumor, breast cancer, bladder cancer, head and neck squamous cell cancer, esophageal squa-mous cell cancer, prostate cancer and pancreatic cancer.The amplification and over-expression of ANO1 are associated with lymph node metastasis and poor prognosis.ANO1 promotes tumor formation and metastasis, and the drugs that inhibit the activity or expression of ANO1 show antitumor effects.Therefore, ANO1 may promote the tumorigenesis, and may be a molecular biomarker and a new target for cancer therapy.

Expression and identification of ANO1 in mouse cardiomyocytes / 中国病理生理杂志

AIM:To explore the expression of anoctamin 1 (ANO1), one of calcium-activated chloride chan-nels ( CaCCs) , in mouse cardiomyocytes and its functional properties.METHODS:The cardiomyocytes from the myocar-dial tissues of C57BL/6 mice were isolated with enzyme and purified by the differential adherent method.The cells were stained with monoclonal anti-sarcomeric actin and Cy3 to evaluate the purity of the myocardial cells.RT-PCR was used to detect the mRNA expression of ANO1 in the mouse cardiomyocytes.The protein expression of ANO1 in the mouse cardio-myocytes was determined by Western blotting analysis.The fluorescence quenching kinetics experiment was used to identify the ion transport properties of ANO1 in the mouse cardiomyocytes.RESULTS: The results of RT-PCR confirmed that ANO1 was expressed in freshly isolated myocardial cells.The results of Western blotting clearly demonstrated the protein expression of ANO1 in primarily cultured myocardial cells.Fluorescence quenching kinetics experiment on freshly isolated single myocardial cell revealed a pronounced outward rectifying property of the ANO1.The functional properties were simi-lar to the classic CaCCs.CONCLUSION:ANO1 expression was identified in the mouse myocardial cells.The function of CaCCs was generated by ANO1, suggesting that ANO1 is the molecular basis of CaCCs.

Expression of anoctamin 1 in Chinese hamster ovary cells and properties of its ion channel / 吉林大学学报(医学版)

Objective To investigate the expression of anoctamin 1 in Chinese hamster ovary cells (CHO)and to analyze the functional properties of its ion channel,and to provide experimental basis for study on the physiological function of calcium-activated chloride channel.Methods The whole sequence of anoctamin 1 was obtained by PCR technique and was subcloned into pcDNA3.1 to construct the expression vector pcDNA3.1-anoctamin 1 was transfected into CHO by liposome-mediated transfection and the CHO stably expressing anoctamin 1 were aquired by selection with zeocin. The expression and distribution of anoctamin 1 in CHO were measured by RT-PCR technique and inverted fluorescence microscope.The functional properties of anoctamin 1 were measured with halide-sensitive fluorescence proteins YFP-H148Q/I152L.The PBS buffer solution with calcimycin and high concentration of iodine ion was used as experimental group,andthe PBS buffer solution without calcimycin and high concentration of iodine ion was used as control group.Results The results of digestion and sequencing confirmed that anoctamin 1 was cloned into pcDNA3.1 by electrophoresis and blast. The results of RT-PCR and inverted fluorescence microscope indicated that anoctamin 1 was expressed in CHO. The results of I- influx as measured by halide-sensitive fluorescence proteins YFP-H148Q/I152L showed that anoctamin 1 had the more functional properties of trans-epithelial transporting I-,and the transporting speed in experimental group was higher than that in control group (P<0.05).Conclusion Anoctamin 1 can be expressed highly in the CHO;Anoctamin 1 expressed in CHO has the characteristics of calcium-activated chloride channel.

Developmental Role of Anoctamin-1/TMEM16A in Ca2+-Dependent Volume Change in Supporting Cells of the Mouse Cochlea

Mammalian cochlea undergoes morphological and functional changes during the postnatal period, around the hearing onset. Major changes during the initial 2 postnatal weeks of mouse include maturation of sensory hair cells and supporting cells, and acquisition of afferent and efferent innervations. During this period, supporting cells in the greater epithelial ridge (GER) of the cochlea exhibit spontaneous and periodic activities which involves ATP, increase in intracellular Ca2+, and cell volume change. This Ca2+-dependent volume change has been proposed to involve chloride channels or transporters. We found that the spontaneous volume changes were eliminated by anion channel blocker, 100 microM NPPB. Among candidates, expression of Anoctamin-1 (Ano1 or TMEM16A), bestriphin-1 and NKCC1 were investigated in whole-mount cochlea of P9-10 mice. Immunolabeling indicated high level of Ano1 expression in the GER, but not of betrophin-1 or NKCC1. Double-labeling with calretinin and confocal image analysis further elucidated the cellular localization of Ano1 immunoreactivity in supporting cells. It was tested if the Ano1 expression exhibits similar time course to the spontaneous activities in postnatal cochlear supporting cells. Cochlear preparations from P2-3, P5-6, P9-10, P15-16 mice were subjected to immunolabeling. High level of Ano1 immunoreactivity was observed in the GER of P2-3, P5-6, P9-10 cochleae, but not of P15-17 cochleae. Taken together, the localization and time course in Ano1 expression pattern correlates with the spontaneous, periodic volume changes recorded in postnatal cochlear supporting cells. From these results we propose that Ano1 is the pacemaker of spontaneous activities in postnatal cochlea.