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voltage-gated potassium channel Kvl.3 in rabbit ciliary epithelium regulates the membrane potential via coupling intracellular calcium

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Chinese Medical Journal 2008年第22期121卷 2272-2277页

作者： LI Yan-feng ZHUO Ye-hong BI Wei-na BAI Yu-jing LI Yan-na WANG Zhi-jian State Key Laboratory of Ophthalmology Zhongshan Ophthalmic Center Sun Yat-sen University Guangzhou Guangdong 510060 China Department of Pediatrics Mount Sinai School of Medicine New York NY 10029 USA Department of Pathology New York Medical College Valhalla NY 10595 USA

Background The cell layer of the ciliary epithelium is responsible for aqueous humor secretion and maintenance. Ion channels play an important role in these processes. The main aim of this study was to determine whether the well-characterized members of the Kvl family （Kv1.3） contribute to the Kv currents in ciliary epithelium. Methods New Zealand White rabbits were maintained in a 12 hours light/dark cycle. Ciliary epithelium samples were isolated from the rabbits. We used Western blotting and immunocytochemistry to identify the expression and location of a voltage-gated potassium channel Kvl.3 in ciliary body epithelium. Membrane potential change after adding of Kvl.3 inhibitor margatoxin （MgTX） was observed with a fluorescence method. Results Western blotting and immunocytochemical studies showed that the Kv1.3 protein expressed in pigment ciliary epithelium and nonpigment ciliary epithelium, however it seemed to express more in the apical membrane of the nonpigmented epithelial cells. One nmol/L margatoxin, a specific inhibitor of Kv1.3 channels caused depolarization of the cultured nonpigmented epithelium （NPE） membrane potential. The cytosolic calcium increased after NPE cell depolarization, this increase of cytosolic calcium was partially blocked by 12.5 μmol/L dantrolene and 10 μmol/L nifedipine. These observations suggest that Kv1.3 channels modulate ciliary epithelium potential and effect calcium dependent mechanisms. Conclusion Kv1.3 channels contribute to K＋ efflux at the membrane of rabbit ciliary epithelium.

关键词： voltage-gated potassium channel Kv1.3 ciliary epithelium membrane potential

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Local Sequence Information-based Support Vector Machine to Classify voltage-gated potassium channels

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Acta Biochimica et Biophysica Sinica 2006年第6期38卷 363-371页

作者： Li-Xia LIU Meng-Long LI Fu-Yuan TAN Min-Chun LU Ke-Long WANG Yan-Zhi GUO Zhi-Ning WEN Lin JIANG College of Chemistry,Sichuan University.Chengdu 610064,China CollegeofChemistry SichuanUniversityChengdu610064China

In our previous work,we developed a computational tool,PreK-ClassK-ClassKv,to predictand classify potassium (K~+) *** K+ channel prediction (PreK) and classification at family level(ClassK),this method performs ***,it does not perform so well in classifying voltage-gatedpotassium (Kv) channels (ClassKv).In this paper,a new method based on the local sequence information ofKv channels is introduced to classify Kv *** transmembrane domains of a Kv channel protein areused to define a protein,and the dipeptide composition technique is used to transform an amino acid sequenceto a numerical sequence.A Kv channel protein is represented by a vector with 2000 elements,and a supportvector machine algorithm is applied to classify Kv *** method shows good performance withaverages of total accuracy (Acc),sensitivity (SE),specificity (SP),reliability (R) and Matthews correlationcoefficient (MCC) of 98.0%,89.9%,100%,0.95 and 0.94 *** results indicate that the localsequence information-based method is better than the global sequence information-based method to classifyKv channels.

关键词： voltage-gated potassium channel classification transmembrane domain dipeptide composition support vector machine

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Effect of genistein on voltage-gated potassium channels in guinea pig proximal colon smooth muscle cells

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World Journal of Gastroenterology 2006年第3期12卷 420-425页

作者： Shi-Ying Li Bin-Bin Huang Shou Ouyang Xiamen Institute of Medicine Xiamen 361003 Fujian Province China

AIM： To investigate the action of genistein （GST）, a broad spectrum tyrosine kinase inhibitor, on voltagegated potassium channels in guinea pig proximal colon smooth muscle cells. METHODS： Smooth muscle cells in guinea pig proximal colon were enzymatically isolated. Nystatin-perforated whole cell patch clamp technique was used to record potassium currents including fast transient outward current （Ikto） and delayed rectifier current （Ikdr）, tWO of which were isolated pharmacologically with 10 mmol/L tetraethylammonium or 5 mmol/L 4-aminopyridine. Contamination of calcium-dependent potassium currents was minimized with no caldum and 0.2 mmol/L CdCl2 in an external solution. RESULTS： GST （10-100 μmol/L） reversibly and dosedependently reduced the peak amplitude of Ikto with an IC50 value of 22.0±6.9 μmol/L. To a lesser extent, Ikdr, was also inhibited in both peak current and sustained current. GST could not totally block the outward potassium current as a fraction of the outWard potassium current, which was insensitive to GST. GST had no effect on the steady-state activation （n =6） and inactivation kinetics （n =6） of Ikto. Sodium orthovanadate （1 retool/L）, a potent inhibitor of tyrosine phosphatase, significantly inhibited GST-induced inhibition （P〈 0.05）. CONCLUSION： GST can dose-dependently and reversibly block voltage-gated potassium channels in guinea pig proximal colon smooth muscle cells.

关键词： Protein tyrosine kinase Patch-clamptechnique Genistein voltage-gated potassium channel Colon Smooth muscle cells

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Modeling protein-protein interactions in axon initial segment to understand their potential impact on action potential initiation

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Neural Regeneration Research 2021年第4期16卷 700-706页

作者： Piyush Bhardwaj Don Kulasiri Sandhya Samarasinghe Centre of Advanced Computational Solutions(C-fACS) Lincoln UniversityChristchurchNew Zealand Department of Molecular Biosciences Lincoln UniversityChristchurchNew Zealand

The axon initial segment(AIS)region is crucial for action potential initiation due to the presence of high-density AIS protein voltage-gated sodium channels(Nav).Nav channels comprise several serine residues responsible for the recruitment of Nav channels into the structure of AIS through interactions with ankyrin-G(AnkG).In this study,a series of computational experiments are performed to understand the role of AIS proteins casein kinase 2 and AnkG on Nav channel recruitment into the *** computational simulation results using Virtual cell software indicate that Nav channels with all serine sites available for phosphorylation bind to AnkG with strong *** the low initial concentration of AnkG and casein kinase 2,the concentration of Nav channels reduces significantly,suggesting the importance of casein kinase 2 and AnkG in the recruitment of Nav channels.

关键词： Alzheimer’s disease ankyrin-G axon initial segment casein kinase-2 microtubules voltage-gated potassium channel voltage-gated sodium channel

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