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Dexmedetomidine Modulates Histamine-induced Ca2+ Signaling and Pro-inflammatory Cytokine Expression
양동기,홍정희 대한약리학회 2015 The Korean Journal of Physiology & Pharmacology Vol.19 No.5
Dexmedetomidine is a sedative and analgesic agent that exerts its effects by selectively agonizing α2 adrenoceptor. Histamine is a pathophysiological amine that activates G protein-coupled receptors, to induce Ca2+ release and subsequent mediate or progress inflammation. Dexmedetomidine has been reported to exert inhibitory effect on inflammation both in vitro and in vivo studies. However, it is unclear that dexmedetomidine modulates histamine-induced signaling and pro-inflammatory cytokine expression. This study was carried out to assess how dexmedetomidine modulates histamine-induced Ca2+ signaling and regulates the expression of pro-inflammatory cytokine genes encoding interleukin (IL)-6 and -8. To elucidate the regulatory role of dexmedetomidine on histamine signaling, HeLa cells and human salivary gland cells which are endogenously expressed histamine 1 receptor were used. Dexmedetomidine itself did not trigger Ca2+ peak or increase in the presence or absence of external Ca2+. When cells were stimulated with histamine after pretreatment with various concentrations of dexmedetomidine, we observed inhibited histamine-induced [Ca2+]i signal in both cell types. Histamine stimulated IL-6 mRNA expression not IL-8 mRNA within 2 hrs, however this effect was attenuated by dexmedetomidine. Collectively, these findings suggest that dexmedetomidine modulates histamine-induced Ca2+ signaling and IL-6 expression and will be useful for understanding the antagonistic properties of dexmedetomidine on histamine-induced signaling beyond its sedative effect.
양동기,송재섭,표현명 한국통신학회 1998 정보와 통신 Vol.15 No.11
전세계적으로 통신선진국들을 중심으로 기존의 유무선과 위성통신까지 통합하게 되는 차세대이동통신 서비스인 IMT-2000 서비스를 개발하기 위한 관련 표준화 작업 및 연구개발을 활발히 진행하고 있다. 한국통신에서도 국내외 표준화 상황에 적극 대처하고 경쟁력있는 IMT-2000 관련 핵심기술 개발 및 기존의 이동통신 서비스와 차별화된 서비스 개발을 위해 COSMOS (Communication System for Mobile multimedia Services)라고 명명된 시험시스템을 개발하고 IMT-2000 응용서비스를 시연한 바 있다. 본 논문에서는 이 IMT-2000 시험시스템의 응용서비스 및 각 단위 시스템에 대한 구조와 기능에 대해서 기술한다.
Five subtypes of muscarinic receptors are expressed in gastric smooth muscles of guinea pig
서인석,양동기,김현진,KyungWanMin,강동묵,김성준,김기환,KiHoPark,전주홍,Kyung-HoChoi,김인규 생화학분자생물학회 2003 Experimental and molecular medicine Vol.35 No.1
Muscarinic receptors play key roles in the control ever, specific physiological functions of each sub-type remain to be determined. In this study, the nonselective cation channel activated by carba-chol (ICCh) was examined in circular smooth mus-cle cels of the guinea pig gastric antrum using patch-clamp technique. 4-DAMP inhibited ICCh dose- dependently with IC50 of 1.10.1 nM (n = 6 ) . G T PγS- induced current, however, was not inhibited by 10 nM 4-DAMP. ICCh was not recorded in pertussis- gastric antrum. ICCh values in response to 10 M Ch at a holding potential of 60 mV were -3032 pA (n=4) and -153 pA (n = 6) in the control and PTX-treated cels, respectively (P< 0.01). Sensi-tivities to nanomolar 4-DAMP and PTX suggest the posible involvement of m4 subtype. Using se-quence information obtained from cloned guinea pig muscarinic receptor genes, it is posible to pig brain tissue. Single cel RT-PCR experiments showed that al five subtypes of muscarinic re-ceptor were present in circular smoth muscle cells of the guinea pig gastric antrum. Together with our previous results showing that Go protein is important for activation of ACh-activated NSC channels, our results suggest that ICCh might be activated by acetylcholine through m4 subtype as wel as m2 and m3 subtypes in guinea-pig sto-mach.
Ahcyl2 upregulates NBCe1-B via multiple serine residues of the PEST domain-mediated association
박필환,안정열,양동기 대한약리학회 2016 The Korean Journal of Physiology & Pharmacology Vol.20 No.4
Inositol-1,4,5-triphosphate [IP3] receptors binding protein released with IP3 (IRBIT) was previously reported as an activator of NBCe1-B. Recent studies have characterized IRBIT homologue S-Adenosylhomocysteine hydrolase-like 2 (AHCYL2). AHCYL2 is highly homologous to IRBIT (88%) and heteromerizes with IRBIT. The two important domains in the N-terminus of AHCYL2 are a PEST domain and a coiledcoil domain which are highly comparable to those in IRBIT. Therefore, in this study, we tried to identify the role of those domains in mouse AHCYL2 (Ahcyl2), and we succeeded in identifying PEST domain of Ahcyl2 as a regulation region for NBCe1-B activity. Site directed mutagenesis and coimmunoprecipitation assay showed that NBCe1-B binds to the N-terminal Ahcyl2-PEST domain, and its binding is determined by the phosphorylation of 4 critical serine residues (Ser151, Ser154, Ser157, and Ser160) in Ahcyl2 PEST domain. Also we revealed that 4 critical serine residues in Ahcyl2 PEST domain are indispensable for the activation of NBCe1-B using measurement of intracellular pH experiment. Thus, these results suggested that the NBCe1-B is interacted with 4 critical serine residues in Ahcyl2 PEST domain, which play an important role in intracellular pH regulation through NBCe1-B.
고주연,명종윤,양동기,서인석 대한약리학회 2017 The Korean Journal of Physiology & Pharmacology Vol.21 No.1
Conflicting evidence has been obtained regarding whether transient receptor potential cation channels (TRPC) are store-operated channels (SOCs) or receptor-operated channels (ROCs). Moreover, the Ca/Na permeability ratio differs depending on whether the current-voltage (I-V) curve has a doubly rectifying shape or inward rectifying shape. To investigate the calcium permeability of TRPC4 channels, we attached GCaMP6s to TRPC4 and simultaneously measured the current and calcium signals. A TRPC4 specific activator, (–)-englerin A, induced both current and calcium fluorescence with the similar time course. Muscarinic receptor stimulator, carbachol, also induced both current and calcium fluorescence with the similar time course. By forming heteromers with TRPC4, TRPC1 significantly reduced the inward current with outward rectifying I-V curve, which also caused the decrease of calcium fluorescence intensity. These results suggest that GCaMP6s attached to TRPC4 can detect slight calcium changes near TRPC4 channels. Consequently, TRPC4- GCaMP6s can be a useful tool for testing the calcium permeability of TRPC4 channels.
Functional identification of protein phosphatase 1-binding consensus residues in NBCe1-B
이규필,김현진,양동기 대한약리학회 2018 The Korean Journal of Physiology & Pharmacology Vol.22 No.1
Protein phosphatase 1 (PP1) is involved in various signal transduction mechanisms as an extensive regulator. The PP1 catalytic subunit (PP1c) recognizes and binds to PP1-binding consensus residues (FxxR/KxR/K) in NBCe1-B. Consequently, we focused on identifying the function of the PP1-binding consensus residue, 922FMDRLK927, in NBCe1-B. Using site-directed mutagenesis and co-immunoprecipitation assays, we revealed that in cases where the residues were substituted (F922A, R925A, and K927A) or deleted (deletion of amino acids 922-927), NBCe1-B mutants inhibited PP1 binding to NBCe1-B. Additionally, by recording the intracellular pH, we found that PP1-binding consensus residues in NBCe1-B were not only critical for NBCe1-B activity, but also relevant to its surface expression level. Therefore, we reported that NBCe1-B, as a substrate of PP1, contains these residues in the C-terminal region and that the direct interaction between NBCe1-B and PP1 is functionally critical in controlling the regulation of the HCO3– transport. These results suggested that like IRBIT, PP1 was another novel regulator of HCO3– secretion in several types of epithelia.