Conclusions
Our results show that cytoplasmic Ca(2+) signals are important for AT-MSCs progression beyond prophase because of their effects on Erk phosphorylation and cyclin B1 expression.
Methods
Here, we used an adenoviral (Ad) vector encoding the Ca(2+) chelator protein parvalbumin (PV) fused to a nuclear exclusion signal (NES) and the Discosoma red fluorescent protein (DsRed) to investigate the function of cytoplasmic Ca(2+) signals on MSC proliferation. Confocal microscopy was used to demonstrate that PV-NES-DsRed was expressed in the cytoplasm. Ca(2+) signaling was monitored by using Fluo-4-AM. Fluorescence-activated cell sorting (FACS) analysis of cells that were stained with propidium iodide was used as a quantitative measure of cell death. The mitotic index was assessed by immunofluorescence, and the expression of cyclins was examined with Western blot.
Results
Our results show that the Ad-PV-NES-DsRed fusion protein decreased serum-induced Ca(2+) signaling and blocked the proliferation of rat adipose-derived MSCs (AT-MSCs) in prophase. FACS analysis revealed that Ad-PV-NES-DsRed did not induce cell death in AT-MSCs. Furthermore, Western blot analysis demonstrated that Ad-PV-NES-DsRed reduced extracellular signal-regulated kinase (Erk1/2) phosphorylation and cyclin B1 expression. Buffering cytosolic Ca(2+) did not alter the expression of cyclins A/D1/D2/D3/E and E2. Conclusions: Our results show that cytoplasmic Ca(2+) signals are important for AT-MSCs progression beyond prophase because of their effects on Erk phosphorylation and cyclin B1 expression.