• Biomolecules & Therapeutics
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• 제19권4호
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• pp.390-397
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• 2011

G protein-coupled receptor kinases (GRKs) and ${\beta}$-arrestins have been known as regulators of G protein-coupled receptors. However, it has been recently reported that GRKs and ${\beta}$-arrestins mediate receptor-mediated cellular responses in a G proteinin-dependent manner. In this scheme, GRKs work as a mediator or a scaffold protein. Among 7 members of the GRK family (GRK1-GRK7), GRK2 is the most extensively studied in vitro and in vivo. GRK2 is involved in cellular migration, insulin signaling, and cardiovascular disease. GRK6 in concert with ${\beta}$-arrestin 2 mediates chemoattractant-stimulated chemotaxis of T and B lymphocytes. GRK5 shuttles between the cytosol and nucleus, and regulates the activities of transcription factors. GRK3 and GRK4 do not seem to have striking effects on cellular responses other than receptor regulation. GRK1 and GRK7 play specific roles in regulation of rhodopsin function. In this review, these newly discovered functions of GRKs are briefly described.

• BMB Reports
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• 제36권2호
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• pp.207-213
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• 2003

Peroxisome proliferator-activated receptors (PPARs) are orphan nuclear hormone receptors that are known to control the expression of genes that are involved in lipid homeostasis and energy balance. PPARs activate gene transcription in response to a variety of compounds, including hypolipidemic drugs. Most of these compounds have high affinity to the ligand-binding domain (LBD) of PPARs and cause a conformational change within PPARs. As a result, the receptor is converted to an activated mode that promotes the recruitment fo co-activators such as the steroid receptor co-activator-1 (SRC-1). Based on the activation mechanism of PPARs (the ligand binding to $PPAR{\gamma}$ induces interactions of the receptor with transcriptional co-activators), we performed Western blot and ELISA. These showed that the indomethacin, a $PPAR{\gamma}$ ligand, increased the binding between $PPAR{\gamma}$ and SRC-1 in a ligand dose-dependent manner. These results suggested that the in vitro conformational change of $PPAR{\gamma}$ by ligands was also induced, and increased the levels of the ligand-dependent interaction with SRC-1. Collectively, we developed a novel and useful ELISA system for the mass screening of $PPAR{\gamma}$ ligands. This screening system (based on the interaction between $PPAR{\gamma}$ and SRC-1) may be a promising system in the development of drugs for metabolic disorders.

• Molecules and Cells
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• 제22권2호
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• pp.198-202
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• 2006

The $P2X_7$ receptor, an ATP-gated cation channel, induces cell death in immune cells and is involved in neurodegenerative diseases. Although the receptor plays various roles in these diseases, the cellular mechanisms involved are poorly understood and antagonists are limited. Here, the development of a cell-based assay for human $P2X_7$ receptor is reported. We established permanent lines of HEK 293 cells expressing a high level of $hP2X_7$ receptor. Functional activity of the $hP2X_7$ receptor was confirmed by whole-cell patch recording of ATP-induced ion currents. Prolonged exposure to ATP resulted in death of the $hP2X_7$-expressing HEK 293 cells and this cell death could be quantified. Two known $P2X_7$ antagonists, PPADS and KN-62, blocked ATP-induced death in a concentration-dependent manner. Thus, this assay can be used to screen for new antagonists of $hP2X_7$ receptors.

• Molecules and Cells
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• 제21권3호
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• pp.315-329
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• 2006

Two, well characterized cationic channels, the ryanodine receptor (RyR) and the canonical transient receptor potential cation channel (TRPC) are briefly reviewed with a particular attention on recent developments related to the interplay between the two channel families.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1996년도 춘계학술대회
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• pp.206-206
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• 1996

The C-terminus ends of the second putative transmembrane domains of both m1 and m2 muscarinic receptors contain a triplet of amino acid residues consisting of leucine (L), tyrosine (Y) and threonine (T), This triplet is repeated as LYT-LYT in m2 receptors at the interface between the second transmembrane domain and the first extracellular loop. Interestingly, however, it is repeated in a transposed fashion (LYT-TYL) in the sequence of m1 receptors. In this work we employed site-directed mutagenesis to investigate the possible significance of this unique sequence diversity for determining the distinct differential drug-receptor interaction and cellular function at m1 muscarinic receptor. Mutation of the LYTTYL sequence of m1 receptors to the corresponding m2 receptor LYTLYT sequence, however, did not result in a significant change in the binding affinity of the agonist carbachol or in the affinity of the majority of a series of receptor antagonists which are able to discriminate between wild-type m1 and m2 receptors. Surprisingly, the LYTLYT ml receptor mutant demonstrated markedly enhanced coupling to activation of phospholipase C without a change in its coupling to increased cyclic AMP formation. There was also an enhanced receptor sensitivity in transducing elevation of intracellular Ca$\^$2+/. These changes were not due to alterations in the rate of receptor. desensitization or sequestration, On the other hand, the reverse LYTLYT-LYTTYL mutation in the m2 receptor did not alter its coupling to inhibition of adenylate cyclase, but slightly enhanced its coupling to stimulation of PI hydrolysis, Our data suggest that the LYTTYL/LYTLYT sequence difference between ml and n12 muscarinic receptors is not involved in determining receptor pharmacology. On the other hand, while these differences might play a role in the modulation of muscarinic receptor coupling to PI hydrolysis, they are not important for specifying coupling of various subtypes of muscarinic receptors to different cellular signaling pathways.

• 한국미생물·생명공학회지
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• 제39권2호
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• pp.140-145
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• 2011

돼지유행성설사 바이러스(porcine epidemic diarrhea virus: PEDV)는 자돈에게 감염 시 수양성설사를 동반한 급성 장염을 유발하며 매우 높은 폐사율을 보이는 그룹 1 코로나바이러스이다. PEDV는 다른 그룹 1 코로나바이러스와 마찬가지로 숙주 세포에 감염 시 aminopeptidase N (APN)을 세포 수용체로 이용한다고 알려져 있다. 코로나바이러스의 spike(S) 단백질은 숙주세포의 표면에 부착과 관련하여 감염 개시에 있어 중요한 역할을 하는 것으로 알려져 있으며 특히 S 단백질의 S1 도메인은 세포 수용체에 특이적인 결합을 매개하는 수용체 결합 도메인(receptor binding domain: RBD)을 포함하고 있는 것으로 알려져 있다. 이미 많은 코로나바이러스의 RBD의 위치가 확인되어져 있지만 PEDV의 RBD에 대해서는 아직까지 알려진 바가 없다. 본 연구에서는 돼지 APN 수용체와 결합을 매개하는 PEDV의 RBD를 규명하기 위해 S1 도메인을 주형으로 하는 일련의 재조합 truncated variant들을 제작하였고 각각의 truncated들이 실제로 pAPN과의 결합을 이루는지에 대하여 실험을 통해 확인하였다. 그 결과 S1 도메인의 N 말단 부분이 pAPN과의 결합에서 중요한 부위임을 확인할 수 있었다. 본 연구에서 도출된 결과는 향후 PEDV의 S 단백질과 pAPN간의 분자적 상호작용을 이해하는 데에 도움을 줄 것으로 판단된다.

• Asian Pacific Journal of Cancer Prevention
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• 제17권10호
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• pp.4643-4646
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• 2016

The CC chemokine receptor 5 (CCR5) delta 32 allele results in a nonfunctional form of the chemokine receptor and has been implicated in a variety of immune-mediated diseases. $CCR5{\Delta}32$ may also predispose one to chronic liver disease or be linked with resistance to HBV infection. This study was undertaken to investigate any association between CCR5 polymorphism with resistance to hepatitis B or susceptibility to HBV infection. A total of 812 Iranian individuals were enrolled into two groups: HBV infected cases (n=357), who were HBsAg-positive, and healthy controls (n=455). We assessed polymorphisms in the CCR5 gene using specific CCR5 oligonucleotide primers surrounding the breakpoint deletion. Genotype distributions of the HBV infected cases and healthy controls were determined and compared. The CCR5/CCR5 (WW) and $CCR5/CCR5{\Delta}32$ (W/D) genotypes were found in (98%) and (2%) of HBV infected cases, respectively. The $CCR5{\Delta}32/{\Delta}32$genotype was not found in HBV infected cases. Genotype distributions of CCR5 in healthy controls were W/W genotype in (87.3%), W/D genotype in (11.2%) and D/D genotype in (1.5%). Heterozygosity for $CCR5/CCR5{\Delta}32$ (W/D) in healthy controls was greater than in HBV infected cases (11.2% vs 2%, p < 0.001). W/D and D/D genotypes were more prominent in healthy controls than in HBV infected cases. This study provides evidence that the $CCR5{\Delta}32$ polymorphism may have a protective effect in resistance to HBV infection at least in the Iranian population.

• Molecules and Cells
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• 제23권1호
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• pp.1-10
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• 2007

Invading pathogens are recognized by diverse germline-encoded pattern-recognition receptors (PRRs) which are distributed in three different cellular compartments: extracellular, membrane, and cytoplasmic. In mammals, the major extracellular PRRs such as complements may first encounter the invading pathogens and opsonize them for clearance by phagocytosis which is mediated by membrane-associated phagocytic receptors including complement receptors. The major membrane-associated PRRs, Toll-like receptors, recognize diverse pathogens and generate inflammatory signals to coordinate innate immune responses and shape adaptive immune responses. Furthemore, certain membrane-associated PRRs such as Dectin-1 can mediate phagocytosis and also induce inflammatory response. When these more forefront detection systems are avoided by the pathogens, cytoplasmic PRRs may play major roles. Cytoplasmic caspase-recruiting domain (CARD) helicases such as retinoic acid-inducible protein I (RIG-I)/melanoma differentiation-associated gene 5 (MDA5), mediate antiviral immunity by inducing the production of type I interferons. Certain members of nucleotide-binding oligomerization domain (NOD)-like receptors such as NALP3 present in the cytosol form inflammasomes to induce inflammatory responses upon ligand recognition. Thus, diverse families of PRRs coordinately mediate immune responses against diverse types of pathogens.

• The Korean Journal of Physiology and Pharmacology
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• 제6권2호
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• pp.63-70
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• 2002

Cholinergic modulation of GABAergic spontaneous miniature inhibitory postsynaptic currents (mIPSCs) by the activation of muscarine receptors was investigated in mechanically dissociated rat nucleus basalis of the Meynert neurons using the conventional whole-cell patch recording configuration. Muscarine $(10{\mu}M)$ reversibly and concentration-dependently decreased mIPSC frequency without affecting the current amplitude distribution. Muscarine action on GABAergic mIPSCs was completely blocked by $1{\mu}M$ methoctramine, a selective $M_2$ receptor antagonist, but not by $1{\mu}M$ pirenzepine, a selective $M_1$ receptor antagonist. NEM $(10{\mu}M),$ a G-protein uncoupler, attenuated the inhibitory action of muscarine on GABAergic mIPSC frequency. Muscarine still could decrease GABAergic mIPSC frequency even in the $Ca^{2+}-free$ external solution. However, the inhibitory action of muscarine on GABAergic mIPSCs was completely occluded in the presence of forskolin. The results suggest that muscarine acts presynaptically and reduces the probability of spontaneous GABA release, and that such muscarine-induced inhibitory action seems to be mediated by G-protein-coupled $M_2$ receptors, via the reduction of cAMP production. Accordingly, $M_2$ receptor-mediated disinhibition of nBM neurons might play one of important roles in the regulation of cholinergic outputs from nBM neurons as well as the excitability of nBM neurons themselves.

• 한국산학기술학회논문지
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• 제6권2호
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• pp.183-188
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• 2005

포유동물에서는 두가지의 receptor가 보고되었다. 각 sample을 RNA extraction, RT-PCR, Realtime-PCR을 실시하여 melatonin 1A, 1B의 발현 양을 분석하였다. MT1A는 cerebellum에서는 3 hours에서 약 1/8배로 감소를 보이고 6 hours에서는 정상치 9 hours에서는 16배정도로 많은 양의 증가율 보였다. 나머지 hippocampus, thalamus, hypothalamus에서는 공통적으로 3 hours에서 많게는 10배에서, 적게는 대조군과 거의 비슷한 1.5배정도의 증가율을 보이고 있으며, 6 hours에서는 모두 감소하는 것을 알 수 있다. MT1B에서는 4 group 모두 3 hours, 6 hours에서 receptor의 양이 확연히 줄어들었다. 9 hours의 경우에는 4 group모두에서 적게는 8배, 많게는 거의 1000배 가까이의 발현 양의 차이가 나타났다.