AIM: To identify and characterize the function of non-mu-scle myosin Ⅱ (NMM Ⅱ) isoforms in primary rat hepatic stellate cells (HSCs).METHODS: Primary HSCs were isolated from male Spra-gue-Dawley rats by pronase/coll...AIM: To identify and characterize the function of non-mu-scle myosin Ⅱ (NMM Ⅱ) isoforms in primary rat hepatic stellate cells (HSCs).METHODS: Primary HSCs were isolated from male Spra-gue-Dawley rats by pronase/collagenase digestion. Total RNA and protein were harvested from quiescent and culture-activated HSCs. NMM Ⅱ isoform (Ⅱ-A, Ⅱ-B and Ⅱ-C) gene and protein expression were measured by RealTime polymerase chain reaction and Western blot analyses respectively. NMM Ⅱ protein localization was visualized in vitro using immunocytochemical analysis. For in vivo assessment, liver tissue was harvested from bile duct-ligated (BDL) rats and NMM Ⅱisoform expression determined by immunohistochemistry. Using a selective myosin Ⅱ inhibitor and siRNA-mediated knockdown of each isoform, NMM Ⅱ functionality inprimary rat HSCs was determined by contraction and migration assays.RESULTS: NMM Ⅱ-A and Ⅱ-B mRNA expression was increased in culture-activated HSCs (Day 14) with sig-niflicant increases seen in all pairwise comparisons (Ⅱ-A: 12.67 ± 0.99 (quiescent) vs 17.36 ± 0.78 (Day 14), P < 0.05; Ⅱ-B: 4.94 ± 0.62 (quiescent) vs 13.90 ±0.85 (Day 14), P < 0.001). Protein expression exhibited similar expression patterns (Ⅱ-A: 1.87 ± 2.50 (quiescent) vs 58.64 ± 8.76 (Day 14), P < 0.05; Ⅱ-B: 1.17 ± 1.93 (quiescent) vs 103.71 ± 21.73 (Day 14), P < 0.05). No signif icant differences were observed in NMM Ⅱ-C mRNA and protein expression between quiescent and activated HSCs. In culture-activated HSCs, NMM Ⅱ-A and Ⅱ-B merged with F-actin at the cellular periphery and throughout cytoplasm respectively. In vitro stud-ies showed increased expression of NMM Ⅱ-B in HSCs activated by BDL compared to sham-operated animals. There were no apparent increases of NMM Ⅱ-A and Ⅱ-C protein expression in HSCs during hepatic BDL injury. To determine the contribution of NMM Ⅱ-A and Ⅱ-B to migration and contraction, NMM Ⅱ-A and Ⅱ-B expres-sion were downregulated with siRNA. NMM Ⅱ-A and/or Ⅱ-B siRNA inhibited HSC migration by approximately 25% compared to scramble siRNA-treated cells. Conversely, siRNA-mediated NMM Ⅱ-A and Ⅱ-B inhibition had no signif icant effect on HSC contraction; however, contraction was inhibited with the myosin Ⅱ inhibitor, blebbistatin (38.7% ± 1.9%).CONCLUSION: Increased expression of NMM Ⅱ-A and Ⅱ-B regulates HSC migration, while other myosin Ⅱclasses likely modulate contraction, contributing to development and severity of liver f ibrosis.展开更多
Myosin Ⅱ plays multiple roles in physiological and pathological functions through its ATPase activity. The present study was designed to optimize a micro-assay of myosin Ⅱ ATPase activity based on molybdenum blue me...Myosin Ⅱ plays multiple roles in physiological and pathological functions through its ATPase activity. The present study was designed to optimize a micro-assay of myosin Ⅱ ATPase activity based on molybdenum blue method, using a known myosin Ⅱ ATPase inhibitor, blebbistatin. Several parameters were observed in the enzymatic reaction procedure, including the concentrations of the substrate(ATP) and calcium chloride, p H, and the reaction and incubation times. The proportion of coloration agent was also investigated. The sensitivity of this assay was compared with the malachite green method and bioluminescence method. Additionally, 20 natural compounds were studied for myosin Ⅱ ATPase inhibitory activity using the optimized method. Our results showed that ATP at the concentration of 5 mmol·L^(-1) and ammonium molybdate : stannous chloride at the ratio of 15 : 1 could greatly improve the sensitivity of this method. The IC50 of blebbistatin obtained by this method was consistent with literature. Compound 8 was screened with inhibitory activity on myosin Ⅱ ATPase. The optimized method showed similar accuracy, lower detecting limit, and wider linear range, which could be a promising approach to screening myosin Ⅱ ATPase inhibitors in vitro.展开更多
文摘AIM: To identify and characterize the function of non-mu-scle myosin Ⅱ (NMM Ⅱ) isoforms in primary rat hepatic stellate cells (HSCs).METHODS: Primary HSCs were isolated from male Spra-gue-Dawley rats by pronase/collagenase digestion. Total RNA and protein were harvested from quiescent and culture-activated HSCs. NMM Ⅱ isoform (Ⅱ-A, Ⅱ-B and Ⅱ-C) gene and protein expression were measured by RealTime polymerase chain reaction and Western blot analyses respectively. NMM Ⅱ protein localization was visualized in vitro using immunocytochemical analysis. For in vivo assessment, liver tissue was harvested from bile duct-ligated (BDL) rats and NMM Ⅱisoform expression determined by immunohistochemistry. Using a selective myosin Ⅱ inhibitor and siRNA-mediated knockdown of each isoform, NMM Ⅱ functionality inprimary rat HSCs was determined by contraction and migration assays.RESULTS: NMM Ⅱ-A and Ⅱ-B mRNA expression was increased in culture-activated HSCs (Day 14) with sig-niflicant increases seen in all pairwise comparisons (Ⅱ-A: 12.67 ± 0.99 (quiescent) vs 17.36 ± 0.78 (Day 14), P < 0.05; Ⅱ-B: 4.94 ± 0.62 (quiescent) vs 13.90 ±0.85 (Day 14), P < 0.001). Protein expression exhibited similar expression patterns (Ⅱ-A: 1.87 ± 2.50 (quiescent) vs 58.64 ± 8.76 (Day 14), P < 0.05; Ⅱ-B: 1.17 ± 1.93 (quiescent) vs 103.71 ± 21.73 (Day 14), P < 0.05). No signif icant differences were observed in NMM Ⅱ-C mRNA and protein expression between quiescent and activated HSCs. In culture-activated HSCs, NMM Ⅱ-A and Ⅱ-B merged with F-actin at the cellular periphery and throughout cytoplasm respectively. In vitro stud-ies showed increased expression of NMM Ⅱ-B in HSCs activated by BDL compared to sham-operated animals. There were no apparent increases of NMM Ⅱ-A and Ⅱ-C protein expression in HSCs during hepatic BDL injury. To determine the contribution of NMM Ⅱ-A and Ⅱ-B to migration and contraction, NMM Ⅱ-A and Ⅱ-B expres-sion were downregulated with siRNA. NMM Ⅱ-A and/or Ⅱ-B siRNA inhibited HSC migration by approximately 25% compared to scramble siRNA-treated cells. Conversely, siRNA-mediated NMM Ⅱ-A and Ⅱ-B inhibition had no signif icant effect on HSC contraction; however, contraction was inhibited with the myosin Ⅱ inhibitor, blebbistatin (38.7% ± 1.9%).CONCLUSION: Increased expression of NMM Ⅱ-A and Ⅱ-B regulates HSC migration, while other myosin Ⅱclasses likely modulate contraction, contributing to development and severity of liver f ibrosis.
基金supported by National Natural Science Foundation of China(No.81274131)the Graduate Student Innovation Plan of Jiangsu Province(CXLX11_0784)+1 种基金Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions2011 Program for Excellent Scientific and Technological Innovation Team of Jiangsu Higher Education
文摘Myosin Ⅱ plays multiple roles in physiological and pathological functions through its ATPase activity. The present study was designed to optimize a micro-assay of myosin Ⅱ ATPase activity based on molybdenum blue method, using a known myosin Ⅱ ATPase inhibitor, blebbistatin. Several parameters were observed in the enzymatic reaction procedure, including the concentrations of the substrate(ATP) and calcium chloride, p H, and the reaction and incubation times. The proportion of coloration agent was also investigated. The sensitivity of this assay was compared with the malachite green method and bioluminescence method. Additionally, 20 natural compounds were studied for myosin Ⅱ ATPase inhibitory activity using the optimized method. Our results showed that ATP at the concentration of 5 mmol·L^(-1) and ammonium molybdate : stannous chloride at the ratio of 15 : 1 could greatly improve the sensitivity of this method. The IC50 of blebbistatin obtained by this method was consistent with literature. Compound 8 was screened with inhibitory activity on myosin Ⅱ ATPase. The optimized method showed similar accuracy, lower detecting limit, and wider linear range, which could be a promising approach to screening myosin Ⅱ ATPase inhibitors in vitro.
