ABSTRACT
Objective To investigate the regulatory effect of adrenomedullin (AM) on the cell-cell contact formation of podocytes and the possible mechanism.Methods Podocytes were treated with AM (10-7 mol/L),AM combined with a PKA inhibitor H89 (10-4 mol/L),and forskolin (10-5 mol/L) as positive control respectively for 12 hours.Immunofluorescent staining was applied to observe the distribution of cell adhesion molecules and actin-associated proteins.Western blotting assay was used to assess their protein levels.Rho GTPases activity was analyzed by GST-pull down assay and their protein levels were tested by Western blotting.Results AM induced the redistribution of adhesion molecules,actin-associated proteins as well as the F-actin at cell-cell contacts between podocytes.This effect was similar to that of forskolin and could be blocked by H89.The levels of those proteins did not change significantly (P ＞ 0.05).AM up-regulated the activities of RhoA,Rac1 and Cdc42 (P ＜ 0.05),which were partially blocked by H89.The protein levels of Rho GTPases showed no difference compared with the control (P ＞ 0.05).Conclusions AM may promote cell-cell contact formation of podocytes,probably through enhancing the activity of Rho GTPases and then resulting in the redistribution of adhesion molecules,actin-associated proteins and F-actin,which is partially mediated through cAMP-PKA signaling pathway.
ABSTRACT
Objective To establish a co-culture system between mesenchymal stem cells (MSCs) and smooth muscle cells (SMCs) in vitro, and study the influence of SMCs on the differentiation of bone marrow MSCs (BMSCs) into SMCs in the co-culture system. Methods Density gradient centrifugation was used to separate and culture BMSCs, and collagenase digestion was employed to separate and culture bladder smooth muscle cells(BSMCs). Then the 2 types of cells were identified respectively. Then the cells were divided into 4 groups, BMSCs culture group (positive control), BSMCs cells culture group (negative control), BMSCs and BSMCs co-culture groups with contact or non-contact. The expression of ?-smooth muscle actin (?-SMA) and calponin were detected by immunofluorescence staining. Western blot analysis was employed to determine protein expression of calponin. Results In contact co-culture group, the positive rate of CD90 abd CD44 were 99.78% and 60.27% respectively in BMSCs, while only 0.21% for CD45. Western blotting showed that BMSCs expressed little calponin, but those contacting with BSMCs had an increasingly stronger expression of calponin with the elapse of contact culture time, while there was no significant change in its expression in BMSCs with contact. Immunofluorescence staining indicated that part of BMSCs were calponin positive at the 8th day after culture, but no positive cell was observed in non-contact culture group and BMSCs culture group. Conclusion The contact between BSMCs and BMSCs can promote the differentiation of BMSCs into SMCs.