• 한국미생물·생명공학회지
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• 제44권1호
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• pp.55-61
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• 2016

본 연구에서는 $BH_4$를 대체할 수 있는 유용물질인 세피아프테린의 생산성 증대를 위하여 GTP 생합성 경로의 유전자들을 동시에 발현할 수 있는 재조합 대장균을 제작하였다. 세피아프테린을 생산할 수 있는 재조합 대장균에서 gmk, ndk 및 guaA-guaB 유전자를 동시에 발현함으로써 세포 내 GTP의 농도가 대조구에 비해 약 200% 이상 증가하였고 $126.1{\pm}9.3mg/l$의 세피아프테린이 생산되었는데 이 결과는 대조구보다 세피아프테린의 생산량이 약 43% 증가된 것이다. GTP 생합성에 관여하는 개별 유전자의 단독 발현 또는 두 가지 유전자의 동시 발현은 세포 내 GTP 농도 향상 큰 영향을 미치지 못했지만 네 가지 유전자 모두를 동시에 발현하는 경우는 세포 내 GTP 농도를 유의적으로 증가시킨다는 것이 확인되었다. 결론적으로 세포 내 GTP 생합성에 관여하는 guaA-guaB, gmk 및 ndk 유전자를 동시에 발현함으로써 재조합 대장균에서 세피아프테린의 생산성 증가를 달성하였다.

• 미생물학회지
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• 제20권4호
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• pp.201-209
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• 1982

An enzyme, named GTP cyclohydorlase, that catalizes the hydrolytic removal of carbon No.S of GTP has been partially purified from extracts of Pseudomonas putida (IAM 1506). The enzyme exists in two molecuar weight forms : a high molecular weight form (150,000) and a low molecular weight from (40,000). The high molecular weight form has been purified 25-fold. Some of the properties of the enzyme are as follows : It functions optimally at pH8.0, and at $52^{\circ}C$. The Km value for GTP is $20{\mu}M$. Divalent cations $(Cd^{2+}\;and\;Hg^{2+})$ 2+/) at a concentration of 5mM inhibit completely the enzyme activity. No metal ion including $Mg^{2+}$ is needed for the catalysis. The enzyme is heat labile ; its half at $57^{\circ}C$ is 1.5 min. Of a number of nucleotides tested, only GDP was used to any extent as substrbte in place of GTP. One of the products of the enzyme is determined to be a dihydro-neopterin compound.

• BMB Reports
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• 제39권5호
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• pp.492-501
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• 2006

Since differentiation therapy is one of the promising strategies for treatment of leukemia, universal efforts have been focused on finding new differentiating agents. In that respect, we used guanosine 5'-triphosphate (GTP) to study its effects on K562 cell line. GTP, at concentrations between 25-200 ${\mu}M$, inhibited proliferation (3-90%) and induced 5-78% increase in benzidine-positive cells after 6-days of treatments of K562 cells. Flow cytometric analyses of glycophorine A (GPA) showed that GTP can induce expression of this marker in more mature erythroid cells in a time- and dose-dependent manner. These effects of GTP were also accompanied with inhibition of DNA synthesis (measured by [$^3H$]-thymidine incorporation) and early S-phase cell cycle arrest by 96 h of exposure. In contrast, no detectable effects were observed when GTP administered to unstimulated human peripheral blood lymphocytes (PBL). However, GTP induced an increase in proliferation, DNA synthesis and viability of mitogen-stimulated PBL cells. In addition, growth inhibition and differentiating effects of GTP were also induced by its corresponding nucleotides GDP, GMP and guanosine (Guo). In heat-inactivated medium, where rapid degradation of GTP via extracellular nucleotidases is slow, the anti-proliferative and differentiating effects of all type of guanine nucleotides (except Guo) were significantly decreased. Moreover, adenosine, as an inhibitor of Guo transporter system, markedly reduced the GTP effects in K562 cells, suggesting that the extracellulr degradation of GTP or its final conversion to Guo may account for the mechanism of GTP effects. This view is further supported by the fact that GTP and Guo are both capable of impeding the effects of mycophenolic acid. In conclusion, our data will hopefully have important impact on pharmaceutical evaluation of guanine nucleotides for leukemia treatments.

• BMB Reports
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• 제28권1호
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• pp.72-78
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• 1995

Time-dependent inactivation of E. coli GTP cyclohydrolase I with a 2',3'-dialdehyde derivative of GTP (oGTP) was directed to the active site of the enzyme, and was dependent on the concentration of oGTP. The kinetics of inactivation were biphasic with a rapid reaction occurring immediately upon exposure of the enzyme to oGTP followed by a slow rate of inactivation. The $K_i$ value of oGTP for the enzyme was 0.25 mM. Inactivation was prevented by preincubation of the enzyme with GTP, the substrate of the enzyme. At 100% inactivation, 2.3 mol of [8.5'-$^3H$]oGTP were bound per each enzyme subunit, which consists of two identical polypeptides. The active site residue which reacted with the affinity label was lysine. oGTP interacted selectively with the ${\varepsilon}$-amino group of lysine in the GTP-binding site to form a morpholine-like structure which was stable without sodium borohydride treatment. However, triphosphate group was eliminated during the hydrolysis step. To identify the active site of the enzyme, [8.5'-$^3H$]oGTP-labeled enzyme was cleaved by endoproteinase Lys-C, and the $^3H$-labeled peptide was purified by HPLC. The amino acid sequence of the active site peptide was Pro-Ser-Leu-Ser-Lys, which corresponds to the aminoterminal sequence of the enzyme.

• 생명과학회지
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• 제29권2호
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• pp.256-264
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• 2019

Lymphotoxin ${\beta}$ receptor ($LT{\beta}R$)는 TNF 계열로 림프조직의 미세구조와 기관형성에 중요한 역할을 한다. MLCK와 ROCK는 세포의 stress fiber 형성조절에 관여하는 주요 신호전달자이다. Fibroblastic reticular cell (FRC)에서 $LT{\beta}R$ 자극을 통한 이런 신호전달자들의 관련성을 알아보기 위해 ML-7 (MLCK 저해제)이 사용되었다. ML7 처리된 FRC에서 SF가 완전히 파괴되었고 anti-$LT{\beta}R$ antibody 처리 세포와 유사하게 ML7 처리 FRC에서 응축된 세포형태를 관찰 할 수 있었다. Y27632로 ROCK를 저해 했을 때 FRC의 액틴 세포골격과 세포형태 변화가 유도 되었다. FRC에서 p-MLC가 액틴과 함께 SF 구성성분을 이루었다. FRC세포 추출물로 Rho-guanosine diphosphate (GDP)/guanosine triphosphate (GTP) 교환활성을 확인했다. Agonistic anti-$LT{\beta}R$ antibody로 $LT{\beta}R$을 자극 했을 때 Rho-GDP/GTP 교환활성이 크게 감소했다. MLCK 저해처럼 $LT{\beta}R$ 자극은 MLC의 인산화를 감소시켰다. Agonistic anti-$LT{\beta}R$ antibody-treated FRC에서 세포골격 구성요소인 세포막과 세포골격 링커 역할을 하는 p-ezrin의 인산화는 감소 되었고 b- actin, 그리고 tubulin 발현도 줄었다. 이런 결과는 FRC의 $LT{\beta}R$ 신호전달을 통한 SF 조절에는 MLCK와 ROCK가 관여하고 있다는 것을 알 수 있었다.

• 대한의생명과학회지
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• 제20권2호
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• pp.70-76
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• 2014

In this study, we investigated the effect of DMSO, a highly dipolar organic liquid, in collagen ($5{\mu}g/ml$)-stimulated platelet aggregation. DMSO inhibited platelet aggregation at 0.5% by inhibiting production of thromboxane $A_2$ ($TXA_2$) which was associated with blocking cyclooxygenase (COX)-1 activity and $TXA_2$ synthase. In addition, DMSO significantly increased the formation of cyclic adenosine monophosphate (cAMP) from adenosine triphosphate (ATP) and cyclic guanosine monophosphate (cGMP) from guanosine triphosphate (GTP). On the other hand, DMSO (0.1~0.5% concentration) did not affect the LDH release which indicates the cytotoxicity. Based on these results, DMSO has anti-platelet effect by regulation of several platelet signaling pathways, therefore we suggest that DMSO could be a novel strategy on many thrombotic disorders.

• 생명과학회지
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• 제28권9호
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• pp.1100-1117
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• 2018

Ras superfamily에 속하는 monomeric small GTPase는 현재까지 170여 종이 알려져 있으며 이들은 세포 신호전달에 있어서 분자 스위치(molecular switch)로 작용하고 있다. Ras GTPase는 guanosine diphosphate (GDP)와 결합하여 불활성화 되거나 혹은 guanosine triphosphate (GTP)와 결합하여 활성화되는 guanosine nucleotide 결합단백질로서 세포내의 수많은 생리작용을 조절하고 있다. 즉, 쉬고 있던 불활성화 상태의 Ras-GDP는 외부 신호에 반응하여 활성화 된 guanine nucleotide exchange factor (GEF)에 의하여 활성형인 Ras-GTP상태로 전환되어 그 하류로 신호를 전달하는 효과기로 작용하게 된다. 신호전달을 마친 Ras-GTP는 다시 불활성형인 Ras-GDP로 전환되어야 하는데 Ras 자체의 GTPase 활성이 미약하여 RasGTPase activating protein (RasGAP)의 도움을 받아야만 한다. 이와 같이 Ras GTPase는 GEF와 GAP의 활성으로 세포 안의 스위치를 켜고 끄게 된다. 현재까지 알려진 인간 암(cancer)의 30% 이상이 돌연변이를 포함하는 Ras switch의 비정상적인 작동에 기인한다는 점이 밝혀져 있으므로 Ras GTPase의 구조와 생리적 기능에 대한 최근의 연구결과들을 요약하였다. 나아가 GTPase activating protein으로서의 기능을 상실한 RasGAP분자의 돌연변이는 세포 안의 Ras 스위치를 계속 켜 두는 상태인 Ras-GTP 상태를 유발함으로서 종국에는 암의 발생을 촉발하게 된다. 이에, 본고에서는 최근에 와서 tumor suppressor로서 알려지면서 암의 치료 표적단백질로 떠오르게 된 RasGAP의 인체생리학적 기능을 고찰하였다. 인간 게놈 안에는 RASA1, NF1, GAP1 family 및 SynGAP family 등에 속하는 14종의 RasGAP 분자들이 존재하는데 이들 GAP분자들의 이상과 인간 질병의 연관성에 대한 최근의 연구결과들에 대해 고찰하였다.

• Journal of Ginseng Research
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• 제39권4호
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• pp.314-321
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• 2015

Background: Ginseng belongs to the genus Panax. Its main active ingredients are the ginsenosides. Interstitial cells of Cajal (ICCs) are the pacemaker cells of the gastrointestinal (GI) tract. To understand the effects of ginsenoside Re (GRe) on GI motility, the authors investigated its effects on the pacemaker activity of ICCs of the murine small intestine. Methods: Interstitial cells of Cajal were dissociated from mouse small intestines by enzymatic digestion. The whole-cell patch clamp configuration was used to record pacemaker potentials in cultured ICCs. Changes in cyclic guanosine monophosphate (cGMP) content induced by GRe were investigated. Results: Ginsenoside Re ($20-40{\mu}M$) decreased the amplitude and frequency of ICC pacemaker activity in a concentration-dependent manner. This action was blocked by guanosine 50-[${\beta}-thio$]diphosphate [a guanosine-5'-triphosphate (GTP)-binding protein inhibitor] and by glibenclamide [an adenosine triphosphate (ATP)-sensitive $K^{+}$ channel blocker]. To study the GRe-induced signaling pathway in ICCs, the effects of 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (a guanylate cyclase inhibitor) and RP-8-CPT-cGMPS (a protein kinase G inhibitor) were examined. Both inhibitors blocked the inhibitory effect of GRe on ICC pacemaker activity. L-NG-nitroarginine methyl ester ($100{\mu}M$), which is a nonselective nitric oxide synthase (NOS) inhibitor, blocked the effects of GRe on ICC pacemaker activity and GRe-stimulated cGMP production in ICCs. Conclusion: In cultured murine ICCs, GRe inhibits the pacemaker activity of ICCs via the ATP-sensitive potassium ($K^{+}$) channel and the cGMP/NO-dependent pathway. Ginsenoside Re may be a basis for developing novel spasmolytic agents to prevent or alleviate GI motility dysfunction.

• 한국수산과학회지
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• 제51권2호
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• pp.163-169
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• 2018

This study examined the expression of heat shock protein 70 (Hsp70) in red seabream Pagrus major infected by the, acanthocephalan parasites Longicollum pagrosomi. We cloned the full-length Hsp70 cDNA from the liver of the red seabream. The full-length cDNA had a 1,950 bp open reading frame (ORF) that encoded a protein of 650 amino acids. The deduced amino acid sequence of Hsp70 contained all of the conserved Hsp70 family signature sequences and an adenosine triphosphate (ATP)/guanosine triphosphate (GTP) binding motif, including the EEVD (consensus sequence that terminates in Hsp70 family) consensus sequence. The expression of Hsp70 mRNA was upregulated int the fish head-kidney and liver, as determined by quantitative real-time PCR. We quantified the Hsp70 mRNA expression in normal red seabream and fish infected fish by L. pagrosomi. The expression of Hsp70 mRNA was significantly higher in the infected red seabream. These results suggest that Hsp70 play a role of protection against stress and inflammation caused by the parasite and may help maintain homeostasis.

• 생명과학회지
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• 제27권10호
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• pp.1199-1206
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• 2017

종양괴사인자 수용체 일종인 Lymphotoxin ${\beta}$ receptor ($LT{\beta}R$)은 림프 구조와 기관 형성에 중요한 역학을 한다. 우리는 fibroblastic reticular cell (FRC)에서 agonistic $anti-LT{\beta}R$ antibody로 $LT{\beta}R$을 자극하면 stress fiber (SF)에 변화가 생긴다는 것을 알았다. MLCK와 ROCK는 세포에서 SF 형성 기여에 중요한 역할을 한다. 본 연구는 MLCK 저해에 초점을 맞추어 $LT{\beta}R$ 신호 전달은 SF 조절로 항섬유화 효과에 대하여 조사하였다. SF 변화에 대한 $LT{\beta}R$의 기능 조사를 위해 agonistic $anti-LT{\beta}R$ antibody로 처리된 FRC와 세포 추출물을 이용하여 immunoblot, fluorescence assay와 Rho-guanosine diphosphate (GDP)/guanosine triphosphate (GTP) exchange 활성 분석법으로 분석하였다. 세포막과 세포골격 연결자 ezrin은 agonistic $anti-LT{\beta}R$ antibody 처리된 FRC에서 완전히 탈인사화가 유도되었다. Actomysoisn에 의한 SF를 확인하였고 인산화 myosin light chain (p-MLC)인 함께 co-localization 되는 것도 확인하였다. ML7 처리된 FRC에서 agonistic $anti-LT{\beta}R$ antibody 처리된 세포에서 관찰되는 유사한 현상인 SF분해, 세포막 응축과 쇠퇴 현상이 나타났다. ROCK 활성저해는 액틴 골격 변화는 유도하였으나 부분적으로 SF가 세포에 남아 있었다. 반면, ML7에 의한 MLCK저해는 SF를 완전히 분해하였다. 또한, $LT{\beta}R$ 자극은 MLC 인산화를 완전히 억제하였지만, Rho-GDP/GTP exchange 활성변화에서는 감소는 되었으나 활성이 완전히 없어지지는 않았다. 결론적으로 이런 결과들은 FRC에서 $LT{\beta}R$신호전달을 통해 유도되는 SF 조절에는 MLCK가 보다 더 강력한 역할을 한다는 것을 제시하고 있다.