• The Korean Journal of Physiology and Pharmacology
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• v.11 no.5
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• pp.207-213
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• 2007

This study was designed to characterize ureteral smooth muscle motility and also to study the effect of forskolin(FSK) and isoproterenol(ISO) on smooth muscle contractility in murine ureter. High $K^+$(50 mM) produced tonic contraction by $0.17{\pm}0.06mN$(n=19). Neuropeptide and neurotransmitters such as serotonin($5{\mu}M$), histamine($20{\mu}M$), and carbarchol(CCh, $10{\sim}50{\mu}M$) did not produce significant contraction. However, CCh($50{\mu}M$) produced slow phasic contraction in the presence of 25 mM $K^+$. Cyclopiazonic acid(CPA, $10{\mu}M$), SR $Ca^{2+}$-ATPase blocker, produced tonic contraction(0.07 mN). Meanwhile, inhibition of mitochondria by protonophore carbnylcyanide m-chlorophenylhydrazone(CCCP) also produced weak tonic contraction(0.01 mN). The possible involvement of $K^+$ channels was also pursued. Tetraethyl ammonium chloride(TEA, 10 mM), glibenclamide($10{\mu}M$) and quinidine($20{\mu}M$) which are known to block $Ca^{2+}$-activated $K^+$ channels($K_{Ca}$ channel), ATP-sensitive $K^+$ channels($K_{ATP}$) and nonselective $K^+$ channel, respectively, did not elicit any significant effect. However, $Ba^{2+}$($1{\sim}2mM$), blocker of inward rectifier $K^+$ channels($K_{IR}$ channel), produced phasic contraction in a reversible manner, which was blocked by $1{\mu}M$ nicardipine, a blocker of dehydropyridine-sensitive voltage-dependent L-type $Ca^{2+}$ channels($VDCC_L$) in smooth muscle membrane. This $Ba^{2+}$-induced phasic contraction was significantly enhanced by $10{\mu}M$ cyclopiazonic acid(CPA) in the frequency and amplitude. Finally, regulation of $Ba^{2+}$-induced contraction was studied by FSK and ISO which are known as adenylyl cyclase activator and $\beta$-adrenergic receptor agonist, respectively. These drugs significantly suppressed the frequency and amplitude of $Ba^{2+}$-induced contraction(p<0.05). These results suggest that $Ba^{2+}$ produces phasic contraction in murine ureteral smooth muscle which can be regulated by FSK and $\beta$-adrenergic stimulation.

• Molecules and Cells
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• v.20 no.3
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• pp.435-441
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• 2005

Classical transient receptor potential channels (TRPCs) are thought to be candidates for the nonselective cation channels (NSCCs) involved in pacemaker activity and its neuromodulation in murine stomach smooth muscle. We aimed to determine the role of TRPC4 in the formation of NSCCs and in the generation of slow waves. At a holding potential of -60 mV, $50{\mu}M$ carbachol (CCh) induced $I_{NSCC}$ of amplitude [$500.8{\pm}161.8pA$ (n = 8)] at -60 mV in mouse gastric smooth muscle cells. We investigated the effects of commercially available antibodies to TRPC4 on recombinant TRPC4 expressed in HEK cells and CCh-induced NSCCs in gastric smooth muscle cells. TRPC4 currents in HEK cells were reduced from $1525.6{\pm}414.4pA$ (n = 8) to $146.4{\pm}83.3pA$ (n = 10) by anti-TRPC4 antibody and $I_{NSCC}$ amplitudes were reduced from $230.9{\pm}36.3pA$ (n = 15) to $49.8{\pm}11.8pA$ (n = 9). Furthermore, $I_{NSCC}$ in the gastric smooth muscle cells of TRPC4 knockout mice was only $34.4{\pm}10.4pA$ (n = 8) at -60 mV. However, slow waves were still present in the knockout mice. Our data suggest that TRPC4 is an essential component of the NSCC activated by muscarinic stimulation in the murine stomach.

• Molecules and Cells
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• v.42 no.3
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• pp.218-227
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• 2019

This study was designed to determine the effects of the long non-coding RNA (lncRNA) plasmacytoma variant translocation 1 (PVT1) on vascular smooth muscle cell (VSMC) apoptosis and extracellular matrix (ECM) disruption in a murine abdominal aortic aneurysm (AAA) model. After injection of PVT1-silencing lentiviruses, AAA was induced in Apolipoprotein E-deficient ($ApoE^{-/-}$) male mice by angiotensin II (Ang II) infusion for four weeks. After Ang II infusion, mouse serum levels of pro-inflammatory cytokines were analysed, and aortic tissues were isolated for histological, RNA, and protein analysis. Our results also showed that PVT1 expression was significantly upregulated in abdominal aortic tissues from AAA patients compared with that in controls. Additionally, Ang II treatment significantly increased PVT1 expression, both in cultured mouse VSMCs and in AAA murine abdominal aortic tissues. Of note, the effects of Ang II in facilitating cell apoptosis, increasing matrix metalloproteinase (MMP)-2 and MMP-9, reducing tissue inhibitor of MMP (TIMP)-1, and promoting switching from the contractile to synthetic phenotype in cultured VSMCs were enhanced by overexpression of PVT1 but attenuated by knockdown of PVT1. Furthermore, knockdown of PVT1 reversed Ang II-induced AAA-associated alterations in mice, as evidenced by attenuation of aortic diameter dilation, marked adventitial thickening, loss of elastin in the aorta, enhanced aortic cell apoptosis, elevated MMP-2 and MMP-9, reduced TIMP-1, and increased pro-inflammatory cytokines. In conclusion, our findings demonstrate that knockdown of lncRNA PVT1 suppresses VSMC apoptosis, ECM disruption, and serum pro-inflammatory cytokines in a murine Ang II-induced AAA model.

• Molecules and Cells
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• v.22 no.1
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• pp.65-69
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• 2006

In murine gastrointestinal myocytes muscarinic stimulation activates nonselective cation channels via a G-protein and $Ca^{2+}$-dependent pathway. We recorded inward cationic currents following application of carbachol ($I_{CCh}$) to murine gastric myocytes held at -60 mV, using the whole-cell patch-clamp method. The properties of the inward cationic currents were similar to those of the nonselective cation channels activated by muscarinic stimulation in other gastrointestinal smooth muscle cells. CCh-induced $I_{CCh}$ and spontaneous decay of $I_{CCh}$ (desensitization of $I_{CCh}$) occurred. Unlike the situation in guinea pig gastric myocytes, desensitization was not affected by varying $[EGTA]_i$. Pretreatment with the PLC inhibitor (U73122) blocked the activation of $I_{CCh}$, and desensitization of $I_{CCh}$ was attenuated in PLC ${\beta}_1$ knock-out mice. These results suggest that the desensitization of $I_{CCh}$ in murine gastric myocytes is not due to a pathway dependent on intracellular $Ca^{2+}$ but to the PLC ${\beta}_1$ pathway.

• Molecules and Cells
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• v.25 no.1
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• pp.78-85
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• 2008

In a search for new molecular pathways associated with asthma, we performed an mRNA differential display analysis using total RNA extracted from the tracheal tissues of ovalbumin (OVA)-challenged mice and sham controls. cDNAs corresponding to mRNAs for which expression levels were altered by OVA-challenge were isolate and sequenced. Twenty-eight genes differentially expressed in sham and OVA challenged mice were identified. A GenBank BLAST homology search revealed that they were related to cytoskeleton remodeling, transcription, protein synthesis and modification, energy production, and cell growth and differentiation. Two were selected for further characterization. Up-regulation of both the perinatal skeletal myosin heavy chain (skMHC) and fast skeletal muscle myosin light chain (skMLC) genes was confirmed by RT-PCR of trachea tissue from OVA challenged mice. Overexpression of skMLC protein was observed in the smooth muscle layers of OVA-challenged mice by immunohistochemistry, and the surface areas stained with skMLC antibody increased in the OVA-challenged mice. The overexpression of skMLC in murine asthma may be associated with the changes of bronchial smooth muscle.

• Proceedings of the Korean Society of Veterinary Pathology Conference
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• 2003.10a
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• pp.7-7
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• 2003

Histological examination of biopsy or postmortem lung tissue from patients with asthma usually reveals thickened airway walls. This change is called airway remodeling, which is characterized by airway eosinophilia, hyperplasia of goblet cells and smooth muscle, and subepithelial fibrosis [1,2]. In this study, we investigated the time-course functional, morphological, biochemical changes of remodeling in a ovalbumin (OVA)-induced murine chronic asthma model. (omitted)

• Journal of Life Science
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• v.15 no.2 s.69
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• pp.186-191
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• 2005

Previous studies have demonstrated that expression of galectin-3, a member of family of beta-galactoside-binding animal lectin, is associated with pathological conditions including cancer, atherosclerosis, and viral infection. An increase of this lectin has been observed after infection by Kirsten murine sarcoma, human T lymphotropic virus-l (HTLV-l), and human immunodeficiency virus-l (HIV-l). Viral transactivation protein Tax of HTLV-l mediates the increase in the lectin. In case of HIV-1, there are evidences that Tat would be related with increase in galectin-3. We investigated whether Tat directly induced galectin-3 expression in cells. We found that HIV-l tat gene activated galectin-3 promoter in RAW264.7 cells. To demonstrate direct induction of galectin-3 by HIV-l tat, we transfected the tat into a rabbit smooth muscle cell line (Rb1) and obtained RblTatCl-2, a clone of cell stably transfected with tat gene. The Rb1TatCl-2 cells exhibited activation of LTR promoter and up-regulation of galectin-3 transcript as well as protein. Our results indicate that HIV-l tat alone is sufficient to induce the expression of galectin-3. The Rb1TatCl-2 cells could be valuable for study of the effect of HIV-1 tat on expression of cellular genes.

• Interdisciplinary Bio Central
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• v.4 no.4
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• pp.12.1-12.6
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• 2012

The advanced glycation endproducts receptor (AGE-R) is a signal transduction receptor for multiligand such as S100b and AGEs. S100b has been demonstrated to activate various cells with important links to atherosclerosis initiation and progression including endothelial cells, and smooth muscle cells via AGE-R, triggering activation of multiple signaling cascades through its cytoplasmic domain. Many studies have suggested AGE-R might even participate in the cardiovascular complications involved in the pathogenesis of type I diabetes. Recently, Small Ubiquitin-Related Modifier 1 (SURM-1 also known as SUMO-1) has been recognized as a protein that plays an important role in cellular post-translational modifications in a variety of cellular processes, such as transport, transcriptional, apoptosis and stability. Computer Database search with SUMOplot Analysis program identified the five potential SURMylation sites in human AGE-R: K43, K44, K123, and K273 reside within the extracellular domain of AGE-R, and lastly K374 resides with the cytosolic domain of AGE-R. The presence of the consensus yKXE motif in the AGE-R strongly suggests that AGE-R may be regulated by SURMylation process. To test this, we decided to determine if AGE-R is SURMylated in living vascular cell system. S100b-stimulated murine aortic vascular smooth muscle cells were used for western blot analysis with relevant antibodies. Taken together, bioinformatics database search and molecular biological approaches suggested AGE-R is SURMylated in living cardiovascular cell system. Whilst SURMylation and AGE-R undoubtedly plays an important role in the cardiovascular biology, it remains unclear as to the exact nature of this contribution under both physiological and pathological conditions.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.4
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• pp.437-445
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• 2018

${\alpha}$-Iso-cubebene (ICB) is a dibenzocyclooctadiene lignin contained in Schisandra chinensis (SC), a well-known medicinal herb that ameliorates cardiovascular symptoms, but the mechanism responsible for this activity has not been determined. To determine the role played by ICB on the regulation of vascular tone, we investigated the inhibitory effects of ICB on vascular contractile responses by adrenergic ${\alpha}$-receptor agonists. In addition, we investigated the role on myosin light chain (MLC) phosphorylation and cytosolic calcium concentration in vascular smooth muscle cells (VSMC). In aortic rings isolated from C57BL/6J mice, ICB significantly attenuated the contraction induced by phenylephrine (PE) and norepinephrine (NE), whereas ICB had no effects on KCl (60 mM)-induced contraction. In vasculatures precontracted with PE, ICB caused marked relaxation of aortic rings with or without endothelium, suggesting a direct effect on VSMC. In cultured rat VSMC, PE or NE increased MLC phosphorylation and increased cytosolic calcium levels. Both of these effects were significantly suppressed by ICB. In conclusion, our results showed that ICB regulated vascular tone by inhibiting MLC phosphorylation and calcium flux into VSMC, and suggest that ICB has anti-hypertensive properties and therapeutic potential for cardiovascular disorders related to vascular hypertension.

• Molecules and Cells
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• v.21 no.3
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• pp.337-342
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• 2006

Interstitial cells of Cajal (ICCs) are pacemaker cells that activate the periodic spontaneous depolarization (pacemaker potentials) responsible for the production of slow waves in gastrointestinal smooth muscle. The effects of vasoactive intestinal polypeptide (VIP) on the pacemaker potentials in cultured ICCs from murine small intestine were investigated by whole-cell patch-clamp techniques. Addition of VIP (50 nM-$1{\mu}M$) decreased the amplitude of pacemaker potentials and depolarized resting membrane potentials. To examine the type of receptors involved in ICC, we examined the effects of the $VIP_1$ agonist and found that it had no effect on pacemaker potentials. Pretreatment with $VIP_1$ antagonist ($1{\mu}M$) for 10 min also did not block the VIP (50 nM)-induced effects. On the other hand exposure to 1H-(1,2,4)oxadiazolo(4,3-A)quinoxalin-1-one (ODQ, $100{\mu}M$), an inhibitor of guanylate cyclase, prevented VIP inhibition of pacemaker potentials. Similarly KT-5823 ($1{\mu}M$) or RP-8-CPT-cGMPS ($10{\mu}M$), inhibitors of protein kinase G (PKG) blocked the effect of VIP (50 nM) on pacemaker potentials as did N-nitro-L-arginine (L-NA, $100{\mu}M$), a non-selective nitric oxide synthase (NOS) inhibitor. These results imply that the inhibition of pacemaker activity by VIP depends on the NO-cGMP-PKG pathway.