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Objective To investigate the role of Rho-associated coiled-coil containing protein kinase 1 (ROCK1) and the relative signal molecules in sensing the mechanical stimulation from tensile strain and regulating the proliferation of vascular smooth muscle cells (VSMCs).Methods Physiological cyclic strain with magnitude of 10％ and at frequency of 1.25 Hz was applied to VSMCs in vitro by using the strain loading system.The proliferation level of VSMCs was analyzed by BrdU ELISA;the expression level of ROCK1,phosphorylations of protein kinase C (PKC) α/β Ⅱ,protein kinase D (PKD) and extracellular regulated protein kinase (ERK) in VSMCs modulated by cyclic strain were detected with Western blotting;the expression of ROCK1 was specifically repressed by using RNA interference (RNAi).Results Compared with the static control,10％ cyclic strain significantly decreased the expression of ROCK1 and phosphorylations of PKD and ERK.The phosphorylation of PKCα/βⅡ decreased significantly under 10％ cyclic strain for 12 h,but returned to normal level after loading for 24 h.Repressed expression of ROCK1 with RNAi significantly down-regulated VSMC proliferation,suppressed phosphorylations of PKCα/βⅡ and PKD,but no obvious changes were found in phosphorylation of ERK.Conclusions Physiological cyclic strain with magnitude of 10％ may repress the phosphorylation of PKCα/βⅡ and PKD via inhibiting the expression of ROCK1,and subsequently affects VSMC proliferation and maintains vascular hemostasis.The investigation on intracellular mechanotransduction network of VSMCs under mechanical stimulation of cyclic strain may contribute to studying the physiological and pathological mechanisms of cardiovascular diseases.
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Objective To elucidate the characteristics of vascular remodeling in pregnant hypertensive rats.Methods Pregnant rats were induced by L-nitro-arginine methylester (L-NAME) to build hypertension models and normal pregnant rats were used as control.Using a programmable sphygmomanometer,the blood pressure was recorded with the tail-cuff method to ensure the hypertension model was successfully replicated.The changes of mean shear stress were determined after the blood viscosity,the average blood flow and the inner diameter in left common carotid artery were measured.To analyze the degree of arterial remodeling,the protein expression levels of collagen Ⅰ (Col Ⅰ) and Ⅲ (Col Ⅲ) were detected by Western blotting,and the media thickness,the inner diameter,the opening angel both in thoracic aorta and carotid artery were determined.Results The mean shear stress of common carotid artery was reduced by (28.52 ± 3.08) ％ with the blood viscosity increasing and the average blood flow decreasing in pregnant hypertensive rats.Compared with control groups,the ratio of media thickness and inner diameter significantly increased in thoracic aorta and carotid artery,while the opening angel decreased in carotid artery and increased in thoracic aorta.With the expression of Col Ⅰ decreasing and Col Ⅲ increasing,the ratio of Col Ⅰ and Col Ⅲ went an apparent decline.Conclusions The mean shear stress is descending in pregnant hypertensive rat,with the remodeling of thoracic aorta and carotid artery.These results may provide new experimental references for further illustrating pathogenesis of pregnant hypertension.
ABSTRACT
Objective To investigate the role of Rho-associated coiled-coil containing protein kinase 1 (ROCK1) and the relative signal molecules in sensing the mechanical stimulation from tensile strain and regulating the proliferation of vascular smooth muscle cells (VSMCs).Methods Physiological cyclic strain with magnitude of 10％ and at frequency of 1.25 Hz was applied to VSMCs in vitro by using the strain loading system.The proliferation level of VSMCs was analyzed by BrdU ELISA;the expression level of ROCK1,phosphorylations of protein kinase C (PKC) α/β Ⅱ,protein kinase D (PKD) and extracellular regulated protein kinase (ERK) in VSMCs modulated by cyclic strain were detected with Western blotting;the expression of ROCK1 was specifically repressed by using RNA interference (RNAi).Results Compared with the static control,10％ cyclic strain significantly decreased the expression of ROCK1 and phosphorylations of PKD and ERK.The phosphorylation of PKCα/βⅡ decreased significantly under 10％ cyclic strain for 12 h,but returned to normal level after loading for 24 h.Repressed expression of ROCK1 with RNAi significantly down-regulated VSMC proliferation,suppressed phosphorylations of PKCα/βⅡ and PKD,but no obvious changes were found in phosphorylation of ERK.Conclusions Physiological cyclic strain with magnitude of 10％ may repress the phosphorylation of PKCα/βⅡ and PKD via inhibiting the expression of ROCK1,and subsequently affects VSMC proliferation and maintains vascular hemostasis.The investigation on intracellular mechanotransduction network of VSMCs under mechanical stimulation of cyclic strain may contribute to studying the physiological and pathological mechanisms of cardiovascular diseases.
ABSTRACT
Objective To elucidate the characteristics of vascular remodeling in pregnant hypertensive rats.Methods Pregnant rats were induced by L-nitro-arginine methylester (L-NAME) to build hypertension models and normal pregnant rats were used as control.Using a programmable sphygmomanometer,the blood pressure was recorded with the tail-cuff method to ensure the hypertension model was successfully replicated.The changes of mean shear stress were determined after the blood viscosity,the average blood flow and the inner diameter in left common carotid artery were measured.To analyze the degree of arterial remodeling,the protein expression levels of collagen Ⅰ (Col Ⅰ) and Ⅲ (Col Ⅲ) were detected by Western blotting,and the media thickness,the inner diameter,the opening angel both in thoracic aorta and carotid artery were determined.Results The mean shear stress of common carotid artery was reduced by (28.52 ± 3.08) ％ with the blood viscosity increasing and the average blood flow decreasing in pregnant hypertensive rats.Compared with control groups,the ratio of media thickness and inner diameter significantly increased in thoracic aorta and carotid artery,while the opening angel decreased in carotid artery and increased in thoracic aorta.With the expression of Col Ⅰ decreasing and Col Ⅲ increasing,the ratio of Col Ⅰ and Col Ⅲ went an apparent decline.Conclusions The mean shear stress is descending in pregnant hypertensive rat,with the remodeling of thoracic aorta and carotid artery.These results may provide new experimental references for further illustrating pathogenesis of pregnant hypertension.
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Objective To investigate the role of rho-associated coiled-coil containing protein kinase 1 (ROCK1) and the relative signal molecules in sensing the mechanical stimulation from tensile strain and regulating the proliferation of vascular smooth muscle cells (VSMCs). Methods Physiological cyclic strain with magnitude of 10% and at frequency of 1.25 Hz was applied to VSMCs in vitro by using strain loading system. The proliferation level of VSMCs was analyzed by BrdU ELISA; the expression level of ROCK1, phosphorylations of protein kinase C (PKC) α/β II, protein kinase D (PKD) and extracellular regulated protein kinase (ERK) in VSMCs modulated by cyclic strain were detected with Western blotting; the expression of ROCK1 was specifically repressed by using RNA interference (RNAi). Results Compared with the static control, 10% cyclic strain significantly decreased the expression of ROCK1 and phosphorylations of PKD and ERK. The phosphorylation of PKCα/βII was decreased significantly under 10% cyclic strain for 12 h, but returned to normal level after 24 h-loading. Repressed expression of ROCK1 with RNAi significantly down-regulated VSMC proliferation, suppressed phosphorylations of PKCα/βII and PKD, but no obvious change was found in phosphorylation of ERK. Conclusions Physiological cyclic strain with magnitude of 10% may repress the phosphorylation of PKCα/βII and PKD via inhibiting the expression of ROCK1, which subsequently affect VSMC proliferation and maintain vascular hemostasis. The investigation on intracellular mechanotransduction network of VSMCs under mechanical stimulation of cyclic strain may contribute to the physiological and pathological mechanisms of cardiovascular diseases.
ABSTRACT
Objective To elucidate the characteristics of vascular remodeling in pregnant hypertensive rats. Methods Pregnant rats were induced by L-nitro-arginine methylester (L-NAME) to build hypertension models and normal pregnant rats were used as control. Using a programmable sphygmomanometer, the blood pressure was recorded with the tail-cuff method to ensure the hypertension model was successfully replicated. The changes of mean shear stress in left common carotid artery were determined after the blood viscosity, the average blood flow and the inner diameter were measured. To analyze the degree of arterial remodeling, the protein expression levels of Collagen I (Col I) and III (Col III) were detected by Western blotting and the media thickness, the inner diameter, the opening angel were determined in both thoracic aorta and carotid artery. Results The mean shear stress of common carotid artery in pregnant hypertensive rats was reduced by (28.52 ± 3.08)% with the blood viscosity increasing and the average blood flow decreasing in pregnant hypertensive rats. Compared with control groups, the ratio of media thickness and inner diameter was significantly increased in thoracic aorta and carotid artery, while the opening angel decreased in carotid artery while increased in thoracic aorta. With the expression of COL I decreasing and COL III increasing, the ratio of Col I and Col III went an apparent decline. Conclusions The mean shear stress is descending, and the remodeling of thoracic aorta and carotid artery are found in pregnant hypertensive rats. These results may provide new experimental references for further illustrating the pathogenesis of pregnant hypertension.
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Objective To investigate the regulating effect and mechanism of microRNA-21 (miR-21) on extracellular matrix (ECM) of vascular smooth muscle cells (VSMCs) by vascular remodeling of hypertension. Methods By narrowing the abdominal aorta in rats, the hypertension models were established and divided into 2-week hypertension group and 4-week hypertension group, and sham-operated group was also established as control. VSMCs from the rat aorta were subjected to 0% (static), 5% (normal) and 15%（hypertensive）elongation strain at a constant frequency of 1.25 Hz and duration of 12 hours, respectively. The expressions of Smad 7 and ECM were detected by Western blotting, and the expression of miR-21 was examined by Real-time RT-PCR. Finally, miR-21 siRNA was used to study the role of miR-21 in the mechanical strain-induced expression of ECM, miR-21 and Smad 7. Results Compared with the sham-operated group, ECM and miR-21 in thoracic aorta of 2-week hypertension group were significantly elevated. Collagen I, collagen III and miR-21 in thoracic aorta of 4-week hypertension group were significantly elevated. Compared with the static and 5% strain groups, the protein expression of collagen I in VSMCs did not show significant change, but the protein expression of collagen III was significantly elevated and Smad 7 expression was significantly decreased in 15% strain group. The cyclic strain also enhanced miR-21 expression in VSMCs. miR-21 inhibitor effectively decreased the expression of miR-21 in VSMCs and protein level of collagen III, while enhanced Smad 7 expression under the static and 15% strain. Conclusions The vascular remodeling of hypertension causes the high expressions of ECM and miR-21. The cyclic strain induces the high expression of miR-21, which via Smad 7 results in enhancing the expression of ECM, collagen III especially, in VSMCs under vascular remodeling of hypertension.
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Objective To investigate the role of receptor for activated C kinase 1 (RACK1) in vascular smooth muscle cells (VSMCs) proliferation modulated by co-cultured endothelial cells (ECs) and shear stress. Methods Using EC/VSMC co-cultured parallel plate flow chamber system, two levels of shear stress, i.e. low shear stress (LowSS, 0.5 Pa) and normal shear stress (NSS, 1.5 Pa), were applied for 12 h. BrdU ELISA was used to detect the proliferation of VSMCs, and Western blot was used to detect the protein expressions of RACK1 and phosphor-Akt. Under the static condition, RNA interference was used to suppress the expression of RACK1 in VSMCs, and then the proliferation of VSMCs and expressions of RACK1 and phosphor-Akt were detected. By using co-culture model (ECs/VSMCs) and separated culture model (ECs//VSMCs), the effect of ECs on expressions of RACK1 and phosphor-Akt in VSMCs was further analyzed. Results Comparative proteomic analysis revealed that LowSS increased the expression of RACK1 in rat aorta. In vitro experiments showed that LowSS induced the proliferation, expressions of RACK1 and phospho Akt in VSMCs co-cultured with ECs. Target RNA interference of RACK1 significantly decreased the proliferation of VSMCs, and the phosphorylation of Akt. In comparison with ECs//VSMCs (separated culture) group, the expression of RACK1 and phosphor-Akt were both up-regulated in the VSMCs co-cultured with ECs (ECs/VSMCs group). Conclusions The expression of RACK1 in VSMCs was modulated by shear stress and neighboring ECs, which might induce cellular proliferation via PI3K/Akt pathway. The investigation on VSMC proliferation and the involved biomechanical mechanism will contribute to understanding and help preventing the pathogenesis and progress of atherosclerosis.
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Objective To investigate the effect from different pore sizes of co culture inserts on the permeability of biomacromolecules through polyethylene terephthalate (PET) membrane so as to solve the key technology problem in mechanobiology experiment on vascular cells. Methods Inserts with 0.4 μm and 1.0 μm pores on the PET membrane were studied using flow chamber system. Low shear stress was subjected to the co-cultured system of endothelial cell (EC)/vascular smooth muscle cell (VSMC) and the concentration of platelet-derived growth factor BB (PDGF-BB) was detected by ELISA. Under the static condition, vascular cells were cultured on the plate (with no cell on PET membrane), on the outer side of PET membrane, and on the both sides of PET membrane, respectively. Then the recombinants PDGF-BB (rPDGF-BB) were added on the different sides of PET membrane. Western blotting was used to detect the change in expressions of p-ERK1/2, p-Akt and Lamin after cells were stimulated by rPGDF BB. Results After low shear stress subjection for 12 h, the concentration of PDGF-BB in the medium from VSMC side was significantly higher than that from EC-side. rPDGF-BB passed through 0.4 μm and 1.0 μm pores on the PET membrane and modulated expressions of p-ERK1/2, p-Akt and Lamin A in cells cultured on the opposite side of PET membrane and cells cultured on the plate separately. When cells were cultured on the both sides of PET membrane, rPDGF-BB only stimulated cells cultured on the same side of 0.4 μm pores on PET membrane, but had no specific effect on cells cultured on the opposite side. Conclusions PET membrane with both 0.4 μm and 1.0 μm pores was permeable to PDGF-BB, and cells cultured on the membrane could affect the permeability. The efficiency of PDGF BB passing through 0.4 μm pores was significantly repressed with cells cultured on the both sides, which was more similar to that in vivo.