| As a widely expressed serine/threonine phosphatase,Protein phosphatase 5(PP5)plays an important role in cell growth,proliferation,differentiation,migration and cell survival under stress conditions.In the thesis,the function of PP5 in lipid metabolism and bone development were investigated using PP5 knockout(PP5 KO)mice.The body weight,whole body fat volume was measured at WT and KO mice fed with high fat diet(HFD).And liver tissue histology was observed.In vitro adipogensis was performed using MEF cell isolated from WT and PP5 KO mice.The genes related lipid metabolism pathway were analyzed by realtme PCR and western bloting.Furthermore,the femur length was measured and the femur structure was scaned by CT between WT and KO mice.In vitro osteoblast differentiation was investigated using MC3T3-E1 cells.The genes related in osteoblast differentiation was analyzed by immunohistochemistry,realtime-PCR and western blotting.The results are as followings:1.Compared with WT mice,PP5 KO mice had lower body weight,smaller lipid droplets in liver,and less fat accumulation in whole body.2.In vitro adipogenesis assay showed lower adipogenic ability in PP5 KO MEFs than that in WT MEFs cells.3.The adipogenic-related genes,including CD36、AP2、PPARγ2、Gult4 in the liver of PP5 KO mice were decreased compared with that in WT mice.Instrestingly,phosphoirylation of GR,and energy metabolism-related protein UCP1 was increased in PP5 KO than that in WT mice by western blotting analysis.4.The femur bone was shorter,and femur diameter was thicker in PP5 KO mice compared with WT mice.5.HE staining and CT scan results showed that compared wtih WT mice,PP5 KO mice have increased bone trabecular numbers,the ratio of bone volume to total volume of femur,and density,also have thicker trabecular and cortical wall.The results also showed the trabecular separation and the retio of bone surfaceare to bone volum were decreased in PP5 KO mice.Biomechanical testing with the 858 Mini Bionix indicated PP5 KO mouse femur maximum loading was significantly reduced.6.The genes which promote osteogenic differentiation,including Opn,Ocn,and Runx2 were significantly increased both in MSC and femur tissue of PP5 KO mice,whilethe genes which suppress osteogenic differentiation,PPARγ1 and PPARγ2 were decreased in femur tissue of KO mice.In the respect of protein,the expression of p-PPARγ protein was significantly increased. |
