Migratory properties of vascular smooth muscle cells on extracellular matrix: a study on inverted coverslip migration assay / 生理学报

Migration of vascular smooth muscle cells (VSMCs) is involved in vascular development and various vascular diseases; however, the molecular mechanisms of VSMC migration remain unclear. In this study, we established an inverted coverslip migration assay to study the migratory properties of cultured VSMCs on extracellular matrix. Pulmonary arterial smooth muscle cells (PASMCs) from rats were cultured and identified by immunocytochemistry. Each coverslip with a confluent monolayer of PASMCs was inverted to a larger coverslip which was coated with phosphate buffered saline (PBS, as a control), poly-D-lysine hydrobromide (PDL), laminin or Matrigel. After 24 h of migration over the larger coverslip, PASMCs were fixed, and reliably quantified. The roles and mechanisms of extracellular matrix in PASMC migration were further studied by wound-healing assay and immunocytochemistry. The results showed that: (1) The purity of the cultured PASMCs was (97 ± 3)%. (2) The number of PASMCs on laminin or Matrigel migrating out from the inverted coverslip was significantly increased compared with that on PBS or PDL, and the migratory distance of PASMCs on laminin or Matrigel was significantly farther than that on PBS or PDL. (3) The motility of PASMCs on laminin or Matrigel was significantly higher than that on PBS at 8 h, 12 h and 24 h after wounding, respectively. (4) F-actin staining showed that F-actin was congregated along the brim of the migrating cells from the inverted coverslip, and vinculin (a cell marker of focal adhesion) staining showed that the distribution of vinculin in PASMCs plated on laminin or Matrigel was significantly lower than that on PBS or PDL. These results suggest that the inverted coverslip migration assay is suitable to study VSMC migration, and laminin and Matrigel substrates may promote VSMC migration through inhibiting the formation of focal adhesion and regulating the cytoskeletal proteins.

Inhibition of Beclin 1 enhances apoptosis by H2O2 in glioma U251 cells / 生理学报

Oxidative stress could induce apoptosis and autophagy process simultaneously, but the role of autophagy is still not clear. Beclin 1, a key gene regulating the preautophagosome formation, is involved in the injury induced by oxidative stress. To observe the role of autophagy in H2O2-induced injury of U251 cells, the recombinant plasmid Psilencer3.1-siRNA-Beclin 1 was transfected into U251 cells by eukaryotic cell transfection technique. Plasmid vector and cell culture medium were used as negative and control groups respectively. The cells were collected 24 h later, and the cell total protein was extracted to detect Beclin 1, Bcl-2 and Bax protein expressions by Western blot. After the Beclin 1-siRNA cells were treated with 1 mmol/L H2O2, the autophagic vacuoles in the cells were stained with monodansylcadaverine (MDC), and the cell apoptotic ratio was determined with PI/Annexin V-FITC staining by flow cytometry analysis. The results showed that the synthetic siRNA decreased the expression of Beclin 1 protein significantly, but had no obvious effect on the levels of Bcl-2 and Bax protein expressions. Compared with those in the control group, the autophagic vacuoles, the level of LC3-II protein expression and the percentage of apoptotic cells increased (P < 0.05) in 1 mmol/L H2O2 group. In Beclin 1-siRNA + H2O2 group, autophagic vacuoles and the levels of LC3-II protein expression decreased obviously, the percentage of apoptotic cells increased significantly compared with that in 1 mmol/L H2O2 group (P < 0.05). H2O2 and autophagy inhibitor 3-methyladenine (3-MA) combination also increased the percentage of apoptotic cells obviously (P < 0.05). These results revealed that the transfection of Psilencer3.1-siRNA-Beclin 1 effectively inhibited the expression of Beclin 1 protein expression, degraded the autophagy level and increased the apoptotic rate in U251 cells under oxidative stress, which was coincident with the effect of autophagy inhibitor 3-MA. This study suggests that autophagy is a cell protective role in oxidative stress process, and the inhibition of autophagy may enhance apoptosis.

Changes of endoplasmic reticulum stress-induced apoptosis in pulmonary tissue of rats with hypoxic pulmonary hypertension / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To investigate the changes of endoplasmic reticulum stress-induced apoptosis in pulmonary tissue of rats with hypoxic pulmonary hypertension.</p><p><b>METHODS</b>Twenty two male SD rats were randomly divided into control group and 4-week hypoxia-hypercapnia group (n=11). The mean pulmonary arterial pressure (mPAP) and the mean carotid arterial pressure (mCAP) were monitored, and the weight ratio of right ventricle (RV) to left ventricle plus septum (LV + S) were measured. The rattish pathological model were assessed by mPAP, mCAP, RV/(LV+ S), vessel wall area/total area (WA/TA), vessel cavity area/total area (CA/TA) and media thickness of pulmonary arteriole (PAMT). The pulmonary apoptotic cells were detected by Hoechst staining. RT-PCR was used to study the genetic expression of caspasel2, glucose regulated protein 78 (GRP78) and GRP94 in pulmonary tissue. The expression of GRP94 and GRP78 proteins in pulmonary tissue were determined by using immunohistochemistry.</p><p><b>RESULTS</b>(1) (The mPAP, RV/(LV + S), WA/TA and PAMT were respectively higher by 50.5%, 37.3%, 72.5% and 137% in hypoxic group than those in control group, while CA/TA was lower by 41.9% (all P < 0.01). There was not significant difference of mCAP between the two groups. (2) Hoechst staining showed that the pulmonary apoptotic cells in hypoxic group outnumbered markedly than those in control group, and the apoptotic cells were mainly in pulmonary tissue, while they were rare in pulmonary vascular smooth muscle cell. (3) Compared with control group, the expression of pulmonary caspasel2, GRP78 and GRP94 mRNA in hypoxic group were higher by 144%, 137% and 80.7% (all P < 0.05), respectively. (4) The expression of pulmonary GRP78 and GRP94 proteins were up-regulated in hypoxic group, and these proteins mainly localized in pulmonary vascular endothelial cell.</p><p><b>CONCLUSION</b>The endoplasmic reticulum stress-induced apoptosis may be one of the mechanism of hypoxic pulmonary hypertension and pulmonary vascular wall remodeling.</p>