• 동의생리병리학회지
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• 제17권2호
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• pp.461-466
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• 2003

The primary mechanism of smooth muscle contraction is phosphorylation of the 20 kDa myosin light chains(LC20) by a myosin light chain kinase(MLCK). Relaxation, then, is generally the result of dephosphorylation of LC20 by myosin phosphatase(MP). Changes in MP activity is one of the important mechanisms in the regulation of Ca2+-sensitivity. Inhibition of MP activity is linked to an increase in phosphorylated myosin light chain(MLC) without an increase in [Ca/sup 2+/]i-levels. It is now generally accepted that Rho-kinase phosphorylates 130 kDa regulatory and myosin binding subunits(M130, MYPT) of MP, which results in an inhibition of MP activity. In addition Rho-kinase can also directly phosphorylate MLC. In the present study, LC20 phosphorylation and MP subunits translocation to the cell membrane were investigated in freshly isolated ferret portal vein smooth muscle single cells treated with PGF2α. We also examined the effect of Y27632(10-5mol/L), Rho-kinase inhibitor, in the MP subunits localization to compare with butanol fraction of Fructus Crataegi in its effect. Butanol fraction of Fructus Crataegi(BFFC; 1㎎/㎖) was more effective in PGF2α induced contraction than those of phenylephrine in its vasodilation effect. It significantly(P<0.05) dephosphorylated the LC20 at time indicated. In addition, the dissociation of subunits are inhibited by BFCF treatment. The results indicate that, in the smooth muscle cells, the relaxation effect of BFFC is associated with increase of MP activity based on inhibition of dissociation of the catalytic and targeting subunits of the phosphatase, and thus decrease the sensitivity of LC20 phosphorylation for Ca/sup 2+/.

• Molecules and Cells
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• 제43권8호
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• pp.749-762
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• 2020

The migration, dedifferentiation, and proliferation of vascular smooth muscle cells (VSMCs) are responsible for intimal hyperplasia, but the mechanism of this process has not been elucidated. WD repeat domain 1 (WDR1) promotes actin-depolymerizing factor (ADF)/cofilin-mediated depolymerization of actin filaments (F-actin). The role of WDR1 in neointima formation and progression is still unknown. A model of intimal thickening was constructed by ligating the left common carotid artery in Wdr1 deletion mice, and H&E staining showed that Wdr1 deficiency significantly inhibits neointima formation. We also report that STAT3 promotes the proliferation and migration of VSMCs by directly promoting WDR1 transcription. Mechanistically, we clarified that WDR1 promotes the proliferation and migration of VSMCs and neointima formation is regulated by the activation of the JAK2/STAT3/WDR1 axis.

• IMMUNE NETWORK
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• 제9권3호
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• pp.106-113
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• 2009

Background: We previously demonstrated remarkable differences in the expression of IL-8/CXCL8 in aortic tissues and vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR) compared to VSMC from normotensive Wistar-Kyoto rats (WKY). In the present study, we investigated the direct effect of IL-8/CXCL8 on expression of 12-lipoxygenase (LO), a hypertensive modulator, in SHR VSMC. Methods: Cultured aortic VSMC from SHR and WKY were used. Expression of 12-LO mRNA was determined by real-time polymerase chain reaction. Phosphorlyation of ERK1/2 and production of 12-LO and angiotensin II subtype 1 ($AT_1$) receptor were assessed by Western blots. IL-8/CXCL8-stimulated DNA synthesis was determined by measuring incorporation of [$^3H$]-thymidine. And effect of IL-8/CXCL8 on vascular tone was determined by phenylephrine-induced contraction of thoracic aortic rings. Results: Treatment with IL-8/CXCL8 greatly increased 12-LO mRNA expression and protein production compared to treatment with angiotensin II. IL-8/CXCL8 also increased the expression of the $AT_1$ receptor. The increase in 12-LO induced by IL-8/CXCL8 was inhibited by treatment with an $AT_1$ receptor antagonist. The induction of 12-LO mRNA production and the proliferation of SHR VSMC by IL-8/CXCL8 was mediated by the ERK pathway. The proliferation of SHR VSMC and the vascular contraction in the thoracic aortic ring, both of which were induced by IL-8/CXCL8, were inhibited by baicalein, a 12-LO inhibitor. Conclusion: These results suggest that the potential role of IL-8/CXCL8 in hypertensive processes is likely mediated through the 12-LO pathway.

• The Korean Journal of Physiology and Pharmacology
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• 제13권2호
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• pp.107-113
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• 2009

Olibanum (Boswellia serrata) has been shown to have anti-inflammatory, anti-arthritic and anticancer effects. This study determined the role of a water extract of olibanum in platelet-derived growth factor (PDGF)-stimulated proliferation and migration of rat aortic smooth muscle cells (RASMCs). PDGF-BB induced the migration and proliferation of RASMCs that were inhibited by olibanum extract in a dose-dependent manner. The PDGF-BB-increased phosphorylation of p38 mitogen-activated protein kinase (MAPK); the heat shock protein (Hsp) 27 was significantly inhibited by the olibanum extract. The effects of PDGF-BB-induced extracellular signal-regulated kinase1/2 was not altered by the olibanum extract. Treatment with olibanum extract inhibited PDGF-BB-stimulated sprout out growth of aortic rings. These results suggest that the water extract of olibanum inhibits PDGF-BB-stimulated migration and proliferation in RASMCs as well as sprout out growth, which may be mediated by the inhibition of the p38 MAPK and Hsp27 pathways.

• BMB Reports
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• 제55권5호
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• pp.244-249
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• 2022

Characterized by abnormal proliferation and migration of vascular smooth muscle cells (VSMCs), neointima hyperplasia is a hallmark of vascular restenosis after percutaneous vascular interventions. Vaccinia-related kinase 1 (VRK1) is a stress adaption-associated ser/thr protein kinase that can induce the proliferation of various types of cells. However, the role of VRK1 in the proliferation and migration of VSMCs and neointima hyperplasia after vascular injury remains unknown. We observed increased expression of VRK1 in VSMCs subjected to platelet-derived growth factor (PDGF)-BB by western blotting. Silencing VRK1 by shVrk1 reduced the number of Ki-67-positive VSMCs and attenuated the migration of VSMCs. Mechanistically, we found that relative expression levels of β-catenin and effectors of mTOR complex 1 (mTORC1) such as phospho (p)-mammalian target of rapamycin (mTOR), p-S6, and p-4EBP1 were decreased after silencing VRK1. Restoration of β-catenin expression by SKL2001 and re-activation of mTORC1 by Tuberous sclerosis 1 siRNA (siTsc1) both abolished shVrk1-mediated inhibitory effect on VSMC proliferation and migration. siTsc1 also rescued the reduced expression of β-catenin caused by VRK1 inhibition. Furthermore, mTORC1 re-activation failed to recover the attenuated proliferation and migration of VSMC resulting from shVrk1 after silencing β-catenin. We also found that the vascular expression of VRK1 was increased after injury. VRK1 inactivation in vivo inhibited vascular injury-induced neointima hyperplasia in a β-catenin-dependent manner. These results demonstrate that inhibition of VRK1 can suppress the proliferation and migration of VSMC and neointima hyperplasia after vascular injury via mTORC1/β-catenin pathway.

• The Korean Journal of Physiology and Pharmacology
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• 제26권5호
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• pp.389-396
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• 2022

The increased expression of receptors for advanced glycation end-product (RAGE) is known as a key player in the progression of vascular remodeling. However, the precise signal pathways regulating RAGE expression in vascular smooth muscle cells (VSMCs) in the injured vasculatures are unclear. Given the importance of mitogen-activated protein kinase (MAPK) signaling in cell proliferation, we investigated the importance of MAPK signaling in high-mobility group box 1 (HMGB1)-induced RAGE expression in VSMCs. In HMGB1 (100 ng/ml)-stimulated human VSMCs, the expression of RAGE mRNA and protein was increased in association with an increase in AGE-induced VSMC proliferation. The HMGB1-induced RAGE expression was attenuated in cells pretreated with inhibitors for ERK (PD98059, 10 μM) and p38 MAPK (SB203580, 10 μM) as well as in cells deficient in ERK and p38 MAPK using siRNAs, but not in cells deficient of JNK signaling. In cells stimulated with HMGB1, the phosphorylation of ERK, JNK, and p38 MAPK was increased. This increase in ERK and p38 MAPK phosphorylation was inhibited by p38 MAPK and ERK inhibitors, respectively, but not by JNK inhibitor. Moreover, AGE-induced VSMC proliferation in HMGB1-stimulated cells was attenuated in cells treated with ERK and p38 MAPK inhibitors. Taken together, our results indicate that ERK and p38 MAPK signaling are involved in RAGE expression in HMGB1-stimulated VSMCs. Thus, the ERK/p38 MAPK-RAGE signaling axis in VSMCs was suggested as a potential therapeutic target for vascular remodeling in the injured vasculatures.

• The Korean Journal of Physiology
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• 제23권2호
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• pp.263-275
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• 1989

Mechanical contractions and electrical activities of the fundic longitudinal and antral circular muscle fibers were investigated in order to elucidate topical differences of gastric motility. K-induced contracture was produced by exposure of muscle strips to high K Tyrode solution. Membrane potential and mechanical contraction were simultaneously recorded by conventional glass microelectrode method and single sucrose-gap technique. All experiments were performed in tris-buffered Tyrode solution which was aerated with $100%\;O_2\;and\;kept\;35^{\circ}C$. The results obtained were as follows: 1) The resting membrane potential of circular muscle cells in the antral region was about 10 mV more negative than that in the fundic region. 2) The membrane potentials decreased almost linearly as the extracellular KCI concentration was increased both in antral circular muscle cells and in fundic longitudinal muscle cells. 3) The thresholdal K concentration of K-contracture was 15 mM (membrane potential, -48 mV) for the antral circular muscle strip and 20 mM for the fundic longitudinal muscle cells. 4) The ratio of membrane permeability coefficient for $Na^+\;and\;K^+,\;P_{Na}/P_K\;({\alpha})$ was 0.065 for antral circular muscle cells and was 0.108 for fundic longitudinal muscle cells. 5) K-contracture of antral and fundic smooth muscle strips showed the contracture composed of phasic and tonic components. The amplitude of the phasic component increased sigmoidally in a dose-dependent manner, whereas that of the tonic component was maximal at a concentration of 40 mM KCI and at the concentrations above or below 40 mM KCI the amplitude was reduced. 6) The inverse relationship between the amplitude of tonic component and extracellular KCI concentration in the range of 40 to 150 mM KCI was more prominent in the antral circular muscle strip than in the fundic longitudinal muscle strip, where the amplitude of the tonic component decreased less steeply and was maintained higher at the same high K concentrations. 7) The tonic component was totally dependent on the external $Ca^{2+}$ and completely abolished by verapamil, while tile phasic component was far less dependent on the external $Ca^{2+}$ and partially suppressed by verapamil. From the above results, the following conclusions could be made. 1) The phasic component of K-contracture is produced both by intracellular $Ca^{2+}$ mobilization and by $Ca^{2+}$-influx from outside, while the tonic component is generated and maintained by the $Ca^{2+}-influx$ through the potential-dependent $Ca^{2+}$ channel. 2) The mechanism of reducing the free $Ca^{2+}$ concentration in the myoplasm seems to be more developed in the antral circular muscle than in the fundic longitudinal muscle. 3) The lower resting membrane potential of the fundic longitudinal muscle cell reflects a relatively high $P_{Na}/P_K$ ratio of about 0.108.

• Journal of Ginseng Research
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• 제23권4호
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• pp.235-238
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• 1999

[ $K_{ATP}$ ]채널은 세포내 ATP에 의해서 억제되는 포타슘 채널로서 혈관평활근, 골격근 및 체장의 ${\beta}$세포 막에 존재하여, 근세포의 막전압 조절을 통하여 근수축 및 이완을 조절할 뿐만 아니라 췌장의 ${\beta}$세포로부터 인슐린분비를 조절한다. 홍삼 복합사포닌 및 사포닌 $Rg_3$ 성분은 토끼 관상동맥 평활근세포의 칼슘의존성-포타슘채널$(BK_{Ca})$의 활성을 증가시켜 막전압의 과분극을 유발하여 혈관평활근을 이완시킨다. 사포닌 $Rg_3$성분은 홍삼의 복합사포닌 성분보다 $BK_{Ca}$에 더 높은 활성을 보이기 때문에 본 연구는 사포닌 $Rg_3$성분이 토끼 관상동맥 단일 평활근세포의 ${\beta}$채널의 활성도를 조절하는지를 팻치클램프 방법으로 기록하였다. 막전압 의존성과 함께 내향전류(inward rectification)특성을 보이는 ${\beta}$채널의 활성을 토끼 관상동맥 평활근 세포로부터 기록하였다. 이 ${\beta}$채널은 ATP와 giyburide에 의해서 억제되었으며 minoxidil에 의해서 활성이 증가되었다. 홍삼 사포닌 $Rg_3$성분은 $K_{ATP}$채널의 전류극대치에는 영향을 주지 않고 전류의 inactivation을 억제시켜 결과적으로 $K_{ATP}$채널의 활성을 증가시켰으며, 단일 KhTr채널이 열리는 시간도 증가시켰다. 따라서 본 실험 결과는 사포닌 $Rg_3$성분이 KATP채널의 활성을 증가시켜 막전압을 조절하여 관상동맥 평활근의 이완을 촉진한다고 여겨진다.

• Molecules and Cells
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• 제21권1호
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• pp.42-51
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• 2006

We investigated the mechanism of contraction induced by S1P in esophageal smooth muscle cells. Western blot analysis demonstrated that $S1P_1$, $S1P_2$, $S1P_3$, and $S1P_5$ receptors existed in the cat esophagus. Only penetration of EDG-5 ($S1P_2$) antibody into permeabilized cells inhibited S1P-induced contraction. Pertussis toxin (PTX) also inhibited contraction, suggesting that it was mediated by $S1P_2$ receptors coupled to a PTXsensitive $G_i$ protein. Specific antibodies to $G_{i2}$, $G_q$ and $G_{\beta}$ inhibited contraction, implying that the S1P-induced contraction depends on PTX-insensitive $G_q$ and $G_{\beta}$ dimers as well as the PTX-sensitive $G_{i2}$. Contraction was not affected by the phospholipase $A_2$ inhibitor DEDA, or the PLD inhibitor ${\rho}$-chloromercuribenzoate, but it was abolished by the PLC inhibitor U73122. Incubation of permeabilized cells with $PLC{\beta}3$ antibody also inhibited contraction. Contraction involved the activation of a PKC pathway since it was affected by GF109203X and chelerythrine. Since $PKC{\varepsilon}$ antibody inhibited contraction, $PKC{\varepsilon}$ may be required. Preincubation of the muscle cells with the MEK inhibitor PD98059 blocked S1P-induced contraction, but the p38 MAP kinase inhibitor SB202190 did not. In addition, co-treatment of cells with GF 109203X and PD98059 did not have a synergistic effect, suggesting that these two kinases are involved in the same signaling pathway. Our data suggest that S1P-induced contraction in esophageal smooth muscle cells is mediated by $S1P_2$ receptors coupled to PTX-sensitive $G_{i2}$ proteins, and PTX-insensitive $G_q$ and $G_{\beta}$ proteins, and that the resulting activation of the $PLC{\beta}3$ and $PKC{\varepsilon}$ pathway leads to activation of a p44/p42 MAPK pathway.

• The Korean Journal of Physiology
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• 제26권2호
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• pp.137-141
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• 1992

The present study was aimed at elucidating the mode of inhibitory action of tricyclic antidepressants on the smooth muscle. Effects of amitriptyline on the isolated detrusor muscle strips of the urinary bladder of the rabbit were examined. The spontaneous rhythmic movement of the muscle preparation was frequently observed, which was decreased or abolished by addition of amitriptyline $(10^{-5}{\sim}10^{-3}\;M)$. The muscle preparation responded with contraction dose dependently to carbachol, of which dose response curve shifted to the right in the presence of either amitriptyline or atropine. However, amitriptyline produced a nonparallel shift, whereas atropine caused a parallel one. In calcium free medium, the contraction response to carbachol was markedly decreased, which was resumed by the addition of $CaCl_2$ (2.5mM), but not in the presence of either amitriptyline or nifedipine. KCI (60 mM) produced a potent contraction, which was abolished in the presence of amitriptyline or nifedipine. These results suggest that amitriptyline, unlike atropine, not only acts as a noncompetitive antagonist at cholinergic muscarine receptors but also inhibits Ca-influx through the muscle cell membrane.