• Journal of Plant Biology
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• 제32권4호
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• pp.285-292
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• 1989

The intracellular localizations of polyamines and their related enzymes were investigated from young spinach leaves. Polyamines were present in all parts of plant cells, both in the subcellular organelles and in the soluble fraction of cytoplasm, however, polyamines were mainly located in the cytosolic fraction. Most activities of L-arginine decarboxylase(ADC) and L-ornithine decarboxylase(ODC), two important enzymes of putrescine and polyamine biosynthesis, were detected in cytosol fraction, while in subcellular organelles the activities were very low. Activities of diamine oxidase(DAO) and polyamine oxidase(PAO), the catabolic enzyme of diamine and polyamine, were not detected in spinach leaves. It was suggested that polyamines and their related synthetic enzymes were located in the soluble fraction of cytoplasm.

• 생명과학회지
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• 제16권3호
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• pp.433-441
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• 2006

폴리아민은 거의 모든 세포에 있어서 성장과 분화에 필수적인 물질이다. 이들 폴리아민의 기작은 상당히 복잡하고 다양하여 그 정확한 작용기전은 아직 확실하지가 않다. 본 논문에서는 폴리아민이 세포 증식을 유도 하기도 하지만 일정농도 이상에서는 오히려 세포사멸을 초래한다는 결과를 밝히고자 한다. 본 실험에 사용된 인간의 전립선 암세포(LNCaP cells)에 있어서, 폴리아민 가운데 putrescien은 세포 증식에 거의 영향을 미치지 않았으나 spermidine과 spermine의 경우 10 ${\mu}M$ 이하에서는 세포 증식을 촉진하였다. 그러나, 20 ${\mu}M$ 이상의 농도에서는 농도와 시간의존적으로 세포사별을 유도 하였다. 폴리아민 처리에 의한 세포사멸의 초기과정인 핵 응축과 염색질 condensation이 Hoechst와 PI 염색에서 뚜렷이 관찰되었다. 또한, 폴리아민 처리시 anti-apoptotic protein으로 알려진 Bcl-2 protein의 발현은 거의 완전히 억제된 반면, pro-apoptotic protein으로 알려진 Bax의 발현은 현저히 증대되었다. 본 연구의 결과에 따르면, 폴리아민에 의해서 유도되는 세포사멸은 세포 내 칼슘농도 변화에 의한 것으로 사료된다. 전립선 암세포에 있어서 폴리아민 처리시 시간과 농도 의존적으로 세포 내 칼슘농도가 증가되었다. 세포막을 통한 칼슘이동을 억제하는 nifedipine과 flufenamic acid 등의 억제제를 처리한 실험 결과 세포내 칼슘증가는 세포 내부의 저장소로부터 칼슘의 유출보다는 주로 세포막상에 있는 비선택적 칼슘통로를 통한 외부의 칼슘 유입에 의한 것으로 판단된다.

• BMB Reports
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• 제28권3호
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• pp.191-196
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• 1995

The role of polyamines in skeletal myoblast differentiation was investigated using the polyamine metabolic inhibitor methylglyoxal bis(guanylhydrazone)(MGBG). Concentrations of intracellular free spermidine and spermine increased 2 to 2.5-fold at the onset of myoblast fusion. The systhesis of actin, and creatine kinase activity both dramatically increased during myotube formation. However, MGBG at a concentration of 0.5 mM not only abolished the increase of intracellular free polyamines, but also reduced cell fusion to almost half the level of untreated cells, without noticeable morphological alteration. The production of actin, and creatine kinase activity were almost completely abolished by MGBG. The inhibition of myoblast fusion by MGBG was partially recovered with 0.1 mM of spermidine or spermine added externally. Results indicate that polyamines are necessary for normal myoblast differentiation. Since the first indication of myoblast differentiation is alignment of muscle cells and membrane fusion of adjacent cells, and since polyamine depletion completely inhibited the synthesis of actin, which might be associted with membranes, polyamine might be involved in myoblast differentiation through membrane reorganization events.

• BMB Reports
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• 제32권2호
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• pp.173-180
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• 1999

The effects of agmatine on the enzymes responsible for the biosynthesis of polyamines, the resultant levels of polyamines, and their effect on the growth of DU145 human prostate tumor cells were investigated. When agmatine was added to the medium, ornithine decarboxylase (ODC, EC 4.1.1.17) activity was substantially reduced, but S-adenosylmethionine decarboxylase (SAMDC, EC 4.1.1.50) activity increased markedly. These changes in ODC and SAMDC activities were the result of an induction of ODC-antizyme and a decreased turnover rate of SAMDC in the presence of agmatine. Accordingly, there was a decrease in the intracellular levels of putrescine and spermidine but an increase in the intracellular level of spermine. Cell growth was markedly inhibited by agmatine treatment and this inhibition was not recovered by the addition of putrescine or spermidine. Our results suggest that agmatine alters the intracellular amounts of polyamine in the cells, closely related to the inhibition of cell growth.

• The Plant Pathology Journal
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• 제18권1호
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• pp.43-49
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• 2002

Direct effects of atmospheric ozone on conidia of the rice blast pathogen, Magnaporthe grisea, were investigated to evaluate ozone-induced effects on infection potential of the rice blast fungus. Acute ozone exposure (200 nl $1^{-1}$, 8 h $day^{-1}$3 days) during sporulation significantly affected conidial morphology, appressorium formation, and disease development on rice loaves. Ozone caused reduction in conidial size and change in conidial shape. Relative cytoplasmic volume of lipids and vacuoles were increased in ozone-exposed conidia. Inhibition of appressorium formation and simultaneous increase in endogenous levee of polyamines were found in ozone-exposed conidia. The inverse relationship between appressorium formation and level of polyamines implies that ozone-mediated increase in intracellular level of polyamines may inhibit appressorium formation in rice blast fungus. Furthermore, rice plants inoculated with ozone-fumigated conidia exhibited less severe disease development than those with unfumigated conidia. This result suggests that the anti-conidial consequence of acute ozone will eventually weaken the rice blasts potential for multiple infection cycle. This further suggests that consequently, rice blast can be transformed from an explosive disease to one that has limited epidemiological potential in the field.

• The Korean Journal of Physiology and Pharmacology
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• 제24권1호
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• pp.101-110
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• 2020

Transient receptor potential canonical 4 (TRPC4) channel is a nonselective calcium-permeable cation channels. In intestinal smooth muscle cells, TRPC4 currents contribute more than 80% to muscarinic cationic current (mIcat). With its inward-rectifying current-voltage relationship and high calcium permeability, TRPC4 channels permit calcium influx once the channel is opened by muscarinic receptor stimulation. Polyamines are known to inhibit nonselective cation channels that mediate the generation of mIcat. Moreover, it is reported that TRPC4 channels are blocked by the intracellular spermine through electrostatic interaction with glutamate residues (E728, E729). Here, we investigated the correlation between the magnitude of channel inactivation by spermine and the magnitude of channel conductance. We also found additional spermine binding sites in TRPC4. We evaluated channel activity with electrophysiological recordings and revalidated structural significance based on Cryo-EM structure, which was resolved recently. We found that there is no correlation between magnitude of inhibitory action of spermine and magnitude of maximum current of the channel. In intracellular region, TRPC4 attracts spermine at channel periphery by reducing access resistance, and acidic residues contribute to blocking action of intracellular spermine; channel periphery, E649; cytosolic space, D629, D649, and E687.

• Molecules and Cells
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• 제45권12호
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• pp.963-975
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• 2022

Exogenous polyamines are able to induce life span and improve glucose homeostasis and insulin sensitivity. However, the effects of exogenous polyamines on adipocyte differentiation and which polyamine transporters mediate them have not been elucidated yet. Here, we identified for the first time that exogenous polyamines can clearly stimulate adipocyte differentiation through polyamine transporters, solute carrier family 3 member A2 (SLC3A2) and SLC7A1. Exogenous polyamines markedly promote 3T3-L1 adipocyte differentiation by increasing the intracellular lipid accumulation and the expression of both adipogenic and lipogenic genes in a concentration-dependent manner. In particular, exogenous putrescine mainly regulates adipocyte differentiation in the early and intermediate stages. Moreover, we have assessed the expression of polyamine transporter genes in 3T3-L1 preadipocytes and adipocytes. Interestingly, the putrescine-induced adipocyte differentiation was found to be significantly suppressed in response to a treatment with a polyamine transporter inhibitor (AMXT-1501). Furthermore, knockdown experiments using siRNA that specifically targeted SLC3A2 or SLC7A2, revealed that both SLC3A2 and SLC7A2 act as important transporters in the cellular importing of exogenous putrescine. Thus, the exogenous putrescine entering the adipocytes via cellular transporters is involved in adipogenesis through a modulation of both the mitotic clonal expansion and the expression of master transcription factors. Taken together, these results suggest that exogenous polyamines (such as putrescine) entering the adipocytes through polyamine transporters, can stimulate adipogenesis.

• Journal of Microbiology
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• 제40권4호
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• pp.305-312
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• 2002

The effects of two natural polyamines (putrescine and spermidine) on the synthesis of ArcA, a response regulator of the Arc two-component signal transduction system, were studied using an E. coli mutant deficient in polyamine biosynthesis. Endogenous polyamine deficiency of the mutant resulted in marked reduction in the ArcA level determined by Western blot analysis. Putrescine supplement to the growth medium effectively increased the ArcA level of the mutant in a concentration-dependent manner. Spermidine also stimulated the ArcA level in the mutant to a greater degree than putrescine. Expression of arcA'::lacZ operon fusion in the mutant was stimulated 6-fold and 10-fold by putrescine and spermidine at a 1mM concentration, respectively, indicating that the stimulatory effect of the polyamines on ArcA synthesis is due to transcriptional induction, and that spermidine is a more potent arcA inducer than putrescine. The polyamine-dependent arcA'::lacZ induction was growth-phase-dependent and independent of either arcA or fnr which are two regulators involved in anaerobic stimulation of the Arch level. These results suggested that putrescine and spermidine polyamines may be potential intracellular signal molecules in the control of arcA expression, and thereby may play an important role in cellular metabolism.

• The Korean Journal of Physiology and Pharmacology
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• 제7권3호
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• pp.131-142
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• 2003

We have studied mutant forms of Kir2.1 in which an aspartate residue (D172), important for gating by intracellular polyamines, is replaced by one of three basic residues (Arg, Lys or His). Such channels are highly selective for $K^+$, but show inward rectification that is a shallow function of voltage compared with that found in wild type. This inward rectification occurs with a reduced affinity for spermine and persists in the absence of polyamines. Though the unitary current-voltage relation shows some inward rectification, it is insufficient to account for that seen under whole cell recording. Channels open and shut under single channel recording, and changes of $P_{open}$ appear to generate inward rectification. In D172H, the reduction in affinity for spermine is greater when His is protonated at low $pH_i$. The effective valency for spermine is reduced from $3.09{\pm}0.07$ in wild type to $1.95{\pm}0.09$ in D172H at $pH_i$ 6.3. In the presence of dual mutants of Kir2.1, where E224 is also replaced, spermine affinity becomes undetectable. However, channels still show inward rectification and open and shut under hyper- and depolarisation, respectively. We suggest that Kir2.1 channel are able to undergo conformation changes; these changes may be important physiologically in generating inward rectification, the normal parameters of which are set by the binding of polyamines such as spermine.

• Asian Pacific Journal of Cancer Prevention
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• 제16권9호
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• pp.3887-3891
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• 2015

Aloe-emodin (1, 8-dihydroxy-3-hydroxyl-methylanthraquinone; AE) and emodin (1,3,8-trihydroxy-6-methylanthraquinone; EM) are anthraquinone derivatives that have been detected in some medical plants and share similar anthraquinone structures. AE and EM have been shown to exhibit anticancer activities in various cancer cell lines; however, the inhibitory effects of these derivatives on the growth of cancer cells were previously reported to be different. Gastric cancer is the second most common cause of cancer cell death worldwide. In the present study, we examined the inhibitory effects of 0.05 mM AE and 0.05 mM EM on the proliferation of the MKN45 human gastric cancer cell line. The proliferation of MKN45 cells was significantly inhibited in AE- and EM-treated groups 24 h and 48 h after treatment. Furthermore, the inhibitory effects of EM were stronger than those of AE. The cell cycle of MKN45 cells were arrested in G0/G1 phase or G0/G1 and G2/M phases by AE and EM, respectively. However, an analysis of intracellular polyamine levels and DNA fragmentation revealed that the mechanisms underlying cell death following cell arrest induced by AE and EM differed.