The Properties of Carbachol-Activated Nonselective Cation Channels at the Single Channel Level in Guinea Pig Gastric Myocytes

Kang, Tong Mook; Kim, Young Chul; Sim, Jae Hoon; Rhee, Jong Chul; Kim, Sung Joon; Uhm, Dae Yong; So, Insuk; Kim, Ki Whan

doi:10.1254/jjp.85.291

Cited by 18 publications

(22 citation statements)

References 20 publications

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“…We have also showed that G o type among GTP-binding proteins is responsible for activating the channel (22). Fourth, the unitary conductance was ϳ25-30 pS (3,13,18,42). The open probability is modulated by extracellular monovalent cation (18).…”

mentioning

confidence: 71%

“…Another property of NSCC CCh is the dependence upon extracellular Ca 2ϩ concentration (12,18). The NSCC was also modulated by extracellular calcium in murine stomach (Fig.…”

Section: Rt-pcr and Expression Of Trp Channelsmentioning

confidence: 94%

“…We isolated single cells from the murine stomach and used the same protocol as that in the guinea pig to record the NSCC ACh (18)(19)(20)22). CCh, similar substance to ACh, induced NSCC in isolated smooth muscle cells from the murine stomach (Fig.…”

Section: Rt-pcr and Expression Of Trp Channelsmentioning

confidence: 99%

“…First, the channel is voltage dependent. Initial reports of the voltagedependent activation indicated a half-maximal activation potential (V 1/2 ) of Ϫ50 mV and steepness factor (k) of Ϫ15 mV (14,18,42). However, the V 1/2 value depended on the concentrations of agonists and the type of extracellular cations used for current recordings (19).…”

mentioning

confidence: 99%

“…Fourth, the unitary conductance was ϳ25-30 pS (3,13,18,42). The open probability is modulated by extracellular monovalent cation (18). Fifth, it is regulated by intracellular Ca 2ϩ concentration ([Ca 2ϩ ] i ) and calmodulin (22).…”

mentioning

confidence: 99%

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

Lee

Kim

et al. 2003

American Journal of Physiology-Gastrointestinal and Liver Physi

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148

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. TRPC5 as a candidate for the nonselective cation channel activated by muscarinic stimulation in murine stomach. Am J Physiol Gastrointest Liver Physiol 284: G604-G616, 2003; 10.1152/ajpgi.00069.2002.-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 ϩ Ͼ K ϩ Ͼ Na ϩ , similar to that in the murine stomach. With 0.2 mM GTP␥S 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 3ϩ 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. transient receptor potential protein

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mentioning

confidence: 71%

“…Another property of NSCC CCh is the dependence upon extracellular Ca 2ϩ concentration (12,18). The NSCC was also modulated by extracellular calcium in murine stomach (Fig.…”

Section: Rt-pcr and Expression Of Trp Channelsmentioning

confidence: 94%

Section: Rt-pcr and Expression Of Trp Channelsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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

Lee

Kim

et al. 2003

American Journal of Physiology-Gastrointestinal and Liver Physi

Self Cite

134

148

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Extracellular disulfide bridges stabilize TRPC5 dimerization, trafficking, and activity

Hong

Kwak

Myeong

et al. 2014

Pflugers Arch - Eur J Physiol

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Crucial cysteine residues can be involved in the modulation of protein activity via the modification of thiol (-SH) groups. Among these reactions, disulfide bonds (S-S) play a key role in the folding, stability, and activity of membrane proteins. However, the regulation of extracellular cysteines in classical transient receptor potential (TRPC) channels remains controversial. Here, we examine the functional importance of the extracellular disulfide bond in TRPC5 in modulating channel gating and trafficking. Specifically, we investigated TRPC5 activity in transiently transfected HEK293 cells with wild-type (WT) or cysteine (C553 and C558) mutants in the pore loop. Using reducing agents, we determined that a disulfide linkage mediates the tetrameric formation of the TRPC5 channel. By measuring the TRPC5 current, we observed that C553S or C558S mutants completely lose channel activity induced by lanthanides or receptor stimulation. Co-expression of TRPC5 (WT) with mutants demonstrated a dominant-negative function in mutants, which inhibited the activity of TRPC5 (WT). We generated TRPC5-TRPC5 dimers and observed reduced activity of WT-mutant (C553S or C558S) dimers compared to WT-WT dimers. When pretreated with reducing agents for 12 h, the TRPC5 current decreased due to a reduction in membrane TRPC5 distribution. In addition, we identified a reduced expression of C553S mutant in plasma membrane. We analyzed a dimeric interaction of wild-type and mutant TRPC5 using co-immunoprecipitation and FRET method, indicating a weak interaction between dimeric partners. These results indicated that the disulfide bond between conserved extracellular cysteines, especially C553, is essential for functional TRPC5 activity by channel multimerization and trafficking.

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Dexamethasone activates transient receptor potential canonical 4 (TRPC4) channels via Rasd1 small GTPase pathway

Wie

Kim

et al. 2014

Pflugers Arch - Eur J Physiol

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Canonical transient receptor potential 4 (TRPC4) channels are calcium-permeable, nonselective cation channels that are widely distributed in mammalian cells. It is generally speculated that TRPC4 channels are activated by Gq/11-PLC pathway or directly activated by Gi/o proteins. Although many mechanistic studies regarding TRPC4 have dealt with heterotrimeric G proteins, here, we first report the functional relationship between TRPC4 and small GTPase, Rasd1. Rasd1 selectively activated TRPC4 channels, and it was the only Ras protein among Ras protein family that can activate TRPC4 channels. For this to occur, it was found that certain population of functional Gαi1 and Gαi3 proteins are essential. Meanwhile, dexamethasone, a synthetic glucocorticoid and anti-inflammatory drug was known to increase messenger RNA (mRNA) level of Rasd1 in pancreatic β-cells. We have found that dexamethasone triggers TRPC4-like cationic current in INS-1 cells via increasing protein expression level of Rasd1. This relationship among dexamethasone, Rasd1, and TRPC4 could suggest a new therapeutic agent for hospitalized diabetes mellitus (DM) patients with prolonged dexamethasone prescription.

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The Properties of Carbachol-Activated Nonselective Cation Channels at the Single Channel Level in Guinea Pig Gastric Myocytes

Cited by 18 publications

References 20 publications

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

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

Extracellular disulfide bridges stabilize TRPC5 dimerization, trafficking, and activity

Dexamethasone activates transient receptor potential canonical 4 (TRPC4) channels via Rasd1 small GTPase pathway

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