The Protein Expression Profile In Rat Osteoblasts Intermittently Exposed To Parathyroid Hormone

Objective: It is well known that the intermittent administration of parathyroid hormone (PTH) can promote bone formation, however the mechanisms of the anabolic effect of PTH on bone is far from clear. To explore into the mechanisms, proteomic approach was used to compare the protein expression profiles between rat osteoblasts(ROBs) with and without intermittent exposure to PTH.Methods: In PTH-treated groups, OBs were cultured in PTH-containing (50ng/ml) medium at first 6h but in vehicle medium at subsequent 18h in a 24h-incubation cycle; in control groups, OBs were cultured in vehicle medium all the cycle. At the third cycle, the cells were collected at the end of 6h and 24h, and the collagenase- digested cells were resolved in cell lysis buffer, the proteins were seperated in two-dimensional gel electrophoresis(2-DE). The differential protein expressions between the two groups of cell were analyzed using image analysis software. The differentially expressed protein spots were selected, digested in-gel with trypsin, and measured by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MADI-TOF-MS), the data obtained from peptide mass fingerprinting (PMF ) were used for protein database search .Results: The reproducible 2-DE images were successfully obtained. There were 7 proteins down-regulated in the intermittently PTH- treated cells harvested at 6h (Itm6h) compared to the control group (Ctr6h); and there were 14 proteins up-regulated and 5 proteins down-regulated in the intermittently PTH-treated cells at 24h (Itm24h) compared to the control group (Ctr24h). 5 out of the 7 down-regulated proteins in Itm6h were...