Myosin light chain 9 (MYL9) is a regulatory light chain of myosin, which plays an important role in various biological processes including cell contraction, proliferation and invasion. MYL9 expresses abnormally in several malignancies including lung cancer, breast cancer, prostate cancer, malignant melanoma and others, which is closely related to the poor prognosis, but the clinical significance for its expression varies with different types of cancer tissues. Further elucidating the molecular mechanism of MYL9 in various types of malignant tumor metastasis is of great significance for cancer prevention and treatment. At the same time, as a molecular marker and potential target, MYL9 may have great clinical value in the early diagnosis, prognosis prediction, and targeted treatment of malignant tumors.
Biomarkers ; Humans ; Lung Neoplasms ; Male ; Myosin Light Chains/metabolism* ; Prognosis ; Prostatic Neoplasms

PURPOSE: Cancer cells develop acquired resistance induced by chemotherapeutic drugs. In this study, we investigated the effects of brief treatment with cytotoxic drugs on the phenotype of breast cancer cells. METHODS: Breast cancer cells MCF7 and BT-474 were briefly treated with paclitaxel or doxorubicin. Clonogenic, migration, and invasion assays were performed on the treated cells. Western blot analysis and RhoA activity assay were also performed. RESULTS: Breast cancer cells when briefly treated with paclitaxel or doxorubicin showed reduced clonogenic ability. Doxorubicin, but not paclitaxel, augmented cell migration and invasion. The invasion-promoting effects of doxorubicin were lost when the two drugs were sequentially used in combination. Myosin light chain (MLC) 2 phosphorylation and RhoA activity were upregulated by doxorubicin and downregulated by paclitaxel. Pretreatment with RhoA inhibitors abolished the migration- and invasion-promoting effects of doxorubicin. CONCLUSION: Doxorubicin activates the RhoA/MLC pathway and enhances breast cancer cell migration and invasion. Therefore, this pathway might be explored as a therapeutic target to suppress anthracycline-enhanced tumor progression.
Blotting, Western ; Breast Neoplasms ; Breast ; Cell Movement ; Doxorubicin ; Myosin Light Chains ; Paclitaxel ; Phenotype ; Phosphorylation ; Up-Regulation

α-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 α-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.
Animals ; Aorta, Thoracic* ; Calcium ; Cytosol ; Endothelium ; Hypertension ; Lignin ; Mice ; Muscle, Smooth, Vascular ; Myosin Light Chains* ; Myosins* ; Norepinephrine ; Phenylephrine ; Phosphorylation* ; Plants, Medicinal ; Rats ; Relaxation ; Schisandra

Ardipusilloside-I is a natural triterpenoid saponin, which was isolated from Ardisia pusilla A. DC. The aim of the study was to evaluate the stimulation of ardipusilloside-I on gastrointestinal motility in vitro and in vivo. The experiment of smooth muscle contraction directly monitored the contractions of the isolated jejunal segment (IJS) in different contractile states, and the effects of ardipusilloside-I on myosin were measured in the presence of Ca²⁺-calmodulin using the activities of 20 kDa myosin light chain (MLC₂₀) phosphorylation and myosin Mg²⁺-ATPase. The effects of ardipusilloside-I on gastro emptying and intestinal transit in constipation-predominant rats were observed, and the MLCK expression in jejuna of constipated rats was determined by western blot. The results showed that, ardipusilloside-I increased the contractility of IJS in a dose-dependent manner and reversed the low contractile state (LCS) of IJS induced by low Ca²⁺, adrenaline, and atropine respectively. There were synergistic effects on contractivity of IJS between ardipusilloside-I and ACh, high Ca²⁺, and histamine, respectively. Ardipusilloside-I could stimulate the phosphorylation of MLC₂₀ and Mg²⁺-ATPase activities of Ca²⁺- dependent phosphorylated myosin. Ardipusilloside-I also stimulated the gastric emptying and intestinal transit in normal and constipated rats in vivo, respectively, and increased the MLCK expression in the jejuna of constipation-predominant rats. Briefly, the findings demonstrated that ardipusilloside-I could effectively excite gastrointestinal motility in vitro and in vivo.
Animals ; Ardisia ; Atropine ; Blotting, Western ; Epinephrine ; Gastric Emptying ; Gastrointestinal Motility* ; Histamine ; In Vitro Techniques ; Muscle, Smooth* ; Myosin Light Chains* ; Myosin-Light-Chain Kinase* ; Myosins* ; Phosphorylation* ; Rats ; Saponins

Obesity is a critical risk factor for the hypertension. Although angiotensin II (Ang II) in obese individuals is known to be upregulated in obesity-induced hypertension, direct evidence that explains the underlying mechanism for increased vascular tone and consequent increase in blood pressure (BP) is largely unknown. The purpose of this study is to investigate the novel mechanism underlying Ang II-induced hyper-contractility and hypertension in obese rats. Eight-week old male Sprague-Dawley rats were fed with 60% fat diet or normal diet for 4 months. Body weight, plasma lipid profile, plasma Ang II level, BP, Ang II-induced vascular contraction, and expression of regulatory proteins modulating vascular contraction with/without Ang II stimulation were measured. As a result, high fat diet (HFD) accelerated age-dependent body weight gaining along with increased plasma Ang II concentration. It also increased BP and Ang II-induced aortic contraction. Basal expression of p-CPI-17 and myosin light chain (MLC) kinase was increased by HFD along with increased phosphorylation of MLC. Ang II-induced phosphorylation of CPI-17 and MLC were also higher in HFD group than control group. In conclusion HFD-induced hypertension is through at least in part by increased vascular contractility via increased expression and activation of contractile proteins and subsequent MLC phosphorylation induced by increased Ang II.
Angiotensin II* ; Angiotensins* ; Animals ; Blood Pressure ; Body Weight ; Contractile Proteins ; Diet ; Diet, High-Fat* ; Humans ; Hypertension ; Male ; Myosin Light Chains ; Obesity ; Phosphorylation ; Phosphotransferases ; Plasma ; Rats ; Rats, Sprague-Dawley ; Risk Factors ; Up-Regulation*

Intestinal disorders often co-occur with inflammation and dysmotility. However, drugs which simultaneously improve intestinal inflammation and co-occurring dysmotility are rarely reported. Atractylodin, a widely used herbal medicine, is used to treat digestive disorders. The present study was designed to characterize the effects of atractylodin on amelioration of both jejunal inflammation and the co-occurring dysmotility in both constipation-prominent (CP) and diarrhea-prominent (DP) rats. The results indicated that atractylodin reduced proinflammatory cytokines TNF-α, IL-1β, and IL-6 in the plasma and inhibited the expression of inflammatory mediators iNOS and NF-kappa B in jejunal segments in both CP and DP rats. The results indicated that atractylodin exerted stimulatory effects and inhibitory effects on the contractility of jejunal segments isolated from CP and DP rats respectively, showing a contractile-state-dependent regulation. Atractylodin-induced contractile-state-dependent regulation was also observed by using rat jejunal segments in low and high contractile states respectively (5 pairs of low/high contractile states). Atractylodin up-regulated the decreased phosphorylation of 20 kDa myosin light chain, protein contents of myosin light chain kinase (MLCK), and MLCK mRNA expression in jejunal segments of CP rats and down-regulated those increased parameters in DP rats. Taken together, atractylodin alleviated rat jejunal inflammation and exerted contractile-state-dependent regulation on the contractility of jejunal segments isolated from CP and DP rats respectively, suggesting the potential clinical implication for ameliorating intestinal inflammation and co-occurring dysmotility.
Animals ; Constipation* ; Cytokines ; Diarrhea* ; Herbal Medicine ; Inflammation* ; Interleukin-6 ; Myosin Light Chains ; Myosin-Light-Chain Kinase ; NF-kappa B ; Phosphorylation ; Plasma ; Rats* ; RNA, Messenger

OBJECTIVE: To study whether the effects of olanzapine on gastrointestinal motility is related to the serotonin antagonism and myosin light chain kinase. METHODS: Male Sprague-Dawley rats were randomly divided into four groups. Olanzapine gavage was performed for each treatment group during the course of 30 continuous days, while the same volume of saline was given to the rats in the control group. Defecation of the rats was observed on days 7 and 30 after olanzapine gavage. The effects of olanzapine on contraction of colonic smooth muscles were observed in ex vivo experiments. A Western blot was used to evaluate expression levels of the serotonin transporter (SERT) and MLCK in colon segments of the rats. RESULTS: ResultsaaCompared to the control group, 5-160 µM of olanzapine could inhibit dose-dependently the contraction of colonic smooth muscle ex vivo experiments. The maximum smooth muscle contraction effects of 5-HT and acetylcholine significantly decreased after treatment with 40-160 µM of olanzapine. Constipation was found in the olanzapine-treated rats on day 7 and have sustained day 30 after gavage. Expression of MLCK in olanzapine-treated rats was significantly decreased, whereas the expression of SERT significantly increased on the day 7, then significantly decreased on the day 30 after olanzapine gavage. CONCLUSION: SERT and MLCK may involve in the inhibition of colonic contraction induced by olanzapine.
Acetylcholine ; Animals ; Antipsychotic Agents ; Blotting, Western ; Colon* ; Constipation ; Defecation ; Gastrointestinal Motility ; Humans ; Male ; Muscle, Smooth ; Myosin Light Chains* ; Myosin-Light-Chain Kinase* ; Myosins* ; Rats ; Rats, Sprague-Dawley ; Serotonin Plasma Membrane Transport Proteins ; Serotonin*

An increase in intracellular Ca2+ is the primary trigger of contraction of gastrointestinal (GI) smooth muscles. However, increasing the Ca2+ sensitivity of the myofilaments by elevating myosin light chain phosphorylation also plays an essential role. Inhibiting myosin light chain phosphatase activity with protein kinase C-potentiated phosphatase inhibitor protein-17 kDa (CPI-17) and myosin phosphatase targeting subunit 1 (MYPT1) phosphorylation is considered to be the primary mechanism underlying myofilament Ca2+ sensitization. The relative importance of Ca2+ sensitization mechanisms to the diverse patterns of GI motility is likely related to the varied functional roles of GI smooth muscles. Increases in CPI-17 and MYPT1 phosphorylation in response to agonist stimulation regulate myosin light chain phosphatase activity in phasic, tonic, and sphincteric GI smooth muscles. Recent evidence suggests that MYPT1 phosphorylation may also contribute to force generation by reorganization of the actin cytoskeleton. The mechanisms responsible for maintaining constitutive CPI-17 and MYPT1 phosphorylation in GI smooth muscles are still largely unknown. The characteristics of the cell-types comprising the neuroeffector junction lead to fundamental differences between the effects of exogenous agonists and endogenous neurotransmitters on Ca2+ sensitization mechanisms. The contribution of various cell-types within the tunica muscularis to the motor responses of GI organs to neurotransmission must be considered when determining the mechanisms by which Ca2+ sensitization pathways are activated. The signaling pathways regulating Ca2+ sensitization may provide novel therapeutic strategies for controlling GI motility. This article will provide an overview of the current understanding of the biochemical basis for the regulation of Ca2+ sensitization, while also discussing the functional importance to different smooth muscles of the GI tract.
Actin Cytoskeleton ; Calcium* ; Gastrointestinal Motility ; Gastrointestinal Tract ; Muscle, Smooth* ; Myofibrils ; Myosin Light Chains ; Myosin-Light-Chain Phosphatase ; Neuroeffector Junction ; Neurotransmitter Agents ; Phosphorylation ; Protein Kinases ; Signal Transduction ; Synaptic Transmission

OBJECTIVETo explore the relationship between electrocardiographic (ECG) and genetic mutations of patients with hypertrophic cardiomyopathy (HCM), and early ECG changes in HCM patients.

METHODSClinical, 12-lead ECG and echocardiographic examination as well as genetic examinations were made in a three-generation Chinses HCM pedigree with 8 family members (4 males). The clinical characterization and ECG parameters were analyzed and their relationship with genotypes in the family was explored.

RESULTSFour missense mutations (MYH7-H1717Q, MYLK2-K324E, KCNQ1-R190W, TMEM70-I147T) were detected in this pedigree. The proband carried all 4 mutations and 5 members carried 2 mutations. Corrected QTc interval of KCNQ1-H1717Q carriers was significantly prolonged and was consistent with the ECG characterization of long QT syndrome. MYLK2-K324E and KCNQ1-R190W carriers presented with Q wave and(or) depressed ST segment, as well as flatted or reversed T waves in leads from anterolateral and inferior ventricular walls. ECG results showed ST segment depression, flat and inverted T wave in the gene mutation carriers with normal echocardiographic examination results. ECG and echocardiographic results were normal in TMEM70-I147T mutation carrier.

CONCLUSIONSThe combined mutations of the genes associated with cardiac ion channels and HCM are linked with the ECG phenotype changes in this HCM pedigree. The variations in ECG parameters due to the genetic mutation appear earlier than the echocardiography and clinical manifestations. Variation in ECG may become one of the indexes for early diagnostic screening and disease progression of the HCM gene mutation carriers.

Brugada Syndrome ; Cardiac Conduction System Disease ; Cardiac Myosins ; Cardiomyopathy, Hypertrophic ; Echocardiography ; Electrocardiography ; Exons ; Genetic Testing ; Genotype ; Humans ; KCNQ1 Potassium Channel ; Long QT Syndrome ; Mutation ; Mutation, Missense ; Myosin Heavy Chains ; Myosin-Light-Chain Kinase ; Pedigree ; Phenotype

OBJECTIVETo investigate the effects of salvianolic acid B (Sal B) on endothelin-1 (ET1)-induced contraction and cytoskeleton reorganization of rat hepatic stellate cells (HSCs).

METHODSHSCs were collected from Sprague-Dawley rats by in situ perfusion with pronase E and isolated by density-gradient centrifugation with Nycodenz. Cells were treated with ET-1, with or without Sal B or Y-27632 (a specific inhibitor of rho-associated protein kinases) pretreatment. HSC contraction was evaluated by collagen gel contraction assay. Cytoskeletal reorganization in response to ET-1 was evaluated by detecting changes in phosphorylation of myosin light chain 2 (MLC2) using glycerol-urea PAGE and the Odyssey Infrared Imaging System. Changes in actin stress fiber polymerization were detected by FITC-labeled phalloidin. Differences between the various cell treatment/pretreatment groups were statistically analyzed.

RESULTSCompared to the untreated control cells, the lattice area of ET-1-treated cells showed significant shrinkage (76.89% ± 3.84% vs. 37.10% ± 5.10%; P less than 0.01). Pretreatment with 105 M Sal B or 105 M Y-27632 significantly reduced ET-1-induced contraction (67.01% ± 4.14% and 77.28% ± 2.00%, respectively; bothP less than 0.01 vs. the ET-1-treated cells). The untreated control cells showed a basal MLC2 phosphorylation of (0.35 ± 0.05) mol PO4/mol MLC2. In contrast, ET-1 treatment elicited a rapid and sustained MLC2 phosphorylation, which was (0.87 ± 0.04) mol PO₄/mol MLC2 at 5 min post-treatment and with the maximal level of (0.96 ± 0.04) mol PO₄/mol MLC2 detected at 30 min post-treatment. The Sal B pretreatment led to a significant decrease in ET-1-induced MLC2 phosphorylation (by 63.1%) and an obvious disassembly of actin stress fibers.

CONCLUSIONSal B effectively inhibits ET-1-induced rat HSC contraction, through its suppressive effects on MLC2 phosphorylation and promotion of the disassembly of actin stress fibers.

Actins ; metabolism ; Animals ; Benzofurans ; pharmacology ; Cardiac Myosins ; metabolism ; Cell Shape ; Cells, Cultured ; Cytoskeleton ; drug effects ; Endothelin-1 ; pharmacology ; Hepatic Stellate Cells ; cytology ; drug effects ; Male ; Myosin Light Chains ; metabolism ; Phosphorylation ; Rats ; Rats, Sprague-Dawley